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/

AMERICAN SEWERAGE PRACTICE

VOLUME I
DESIGN OF SEWERS

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AMERICAN SEWERAGE PRACTICE

THREE VOLUMES

BY

METCALF AND EDDY

. Vol.

I

—Design of Sewers

Vol.

II

—Construction op Sewers

(/n Pre»s)

:^: Vol.

III

— Disposal op Sewage

(/n Preparation)

o c

V-

o
o

o

f;

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AMEKICAN
SEWERAGE PRACTICE

o

o d 3 VOLUME I

b^ i DESIGN OF SEWERS

• o o

^ H ^^

M €t ct

o y »•

•^ ^ " BY

3 ^ LEONARD METCALF

• X ANI>

3 a

0 HARRISON P. EDDY

OB 0
O ••

0

o

|1 First Edition

£S
0
0

n

,«. » 1

McGRAW-HELL BOOK COMPANY, Inc.
239 WEST 39TII STREET, XEW YORK

6 BOUVERIE STUEKT, LONDON, E. C.
1914

tkf; riKv; v -^j^
PUELIl L-'--/ ry

ASrOR, Lf \OX AND
TILD£N FOLNDA.iONS

R 19'b L

Copyright, 1914, by the
McGraw-Hill Book Company, Inc.

THE*MAPLB*FRBSB*TORK. I'A

PREFACE

About three years ago the authors undertook the preparation of a
book bringing together in a fomi convenient for ready reference the more
important j)rinciple« of theor}^ and rules of practice in the design and
opt*rtttir>n of sewerage workn, using this tcrna in its broadest sense. It
wa« found* however^ that to make the^e fuiidamental data, tables^ dia-
grama and rulea of the greatest service, it waa desirable to explain them in
Home detail, for such explanations can only be found scattered through
iiuuiy upecial treatises, traiLsactionii of technical societies, engineering
jo«nia!i» and reports. Tn some eas ^ it developed, to the authors* 8ur-
pri«?, that nothing really definite had ever been published concerning
many important features of sewerage practice. In other cases the prac-
tiee of different engineers, being based upon their individual expe-
rJeocef*^ varied considerably. These conditions led the authors to
braadcn the^cope of the work and to devote considerable space to topics
QpoD which Uttie had been written, in order that the refidcr might find
&U ol the hifiinTiation which It was reaaonable to expect in a comprehen-
•i ' ' ( subjert of such scope a,^ sewerage practice. It thus l)e-

cai to present the subject in tliree volumes, the first dealing

with the UeMigii of Sewerage Hystems, the second with their Construe*
lioD^ Aiid t!ie third with the Design of Works for itx Treatment and
l>brpa«ii of Sewage.

iH chapters of this volume haie devclbped much interest
Iti M in the work by different erjriiKQrs, .In^th at home and

Alircmd* who have supplied many helpful suggcfrtions/ ViJuabbj state-
turtittf of ttteir views upon subjects where expefii?nc/>iariVifthes a^ guide
Mflcn mort* helpful tlmn theory, and tlra wings of sjjecial* *structiift>8 to
il' hvir standard practice in design^ To theV- engineers hearty

t' given for their cordial assistance in the autliors' attempt to

fftandard practice and sound principles of design.
- rineering journals have proved of valuable help, particularly
i^- -^ f'xamples of practice and for their records of the develop-

Oi * ihiV m<'thods; and many manufacturers have Ijeen most

^' ipplying drawings, photographs and specific information*

In thi* preparati<m of certain chapters of this volume, sjiecial aid has
bctm I T * ' from "The Theory of Loads on Pipes in Ditches,*' by
Pr*^^^" 'I Marston and A* O, Anderson (Iowa State College of

Au luid Mcchtinic *lrts); "A Treatise on Concrete, Plain and

f^ " ''^^ ^''•^•derick W. Taylor and Sanford E, Thompson (John

V

VI

PREFACE

Wiley & Sons) ; '^ Principles of Reinfoi^ed Concrete Construction/* by
Professors F, E. Tiirneuurc and E. R. Maurer (John Wiley &: Soils);
^* A Treatise on Hydraulics," by Professor liector J. Hughes ixnd jVrlhur
T. Safford (copyright, 1011, The Macnnllan Company); ''American
Civil Engineer's Pouket Book/' edited hy Mansfield Merriman (John
Wiley & Sons); and '*A Treatise on Masonry Construction;" by Pro-
fessor Ira 0. Baker (John W^iley & Sons)* Wliile acknowledjctnent
has been made in the several chapters, for this help, more specihc thanks
are here given for the generous permission to make such free use of thei?e
valuable contributions to engineering literature. The authors have
also drawn upon the late August Friihlmg's valualnle " Entwasserung
der Stadte/' published by Wilhelm Engelmann.

The authors are under obligations to their junior parinrrM, Cliarles W*
Sherman, William T, Barrtes and .AJioon L, Fales, and to their office
staBf, particularly William L. Butcher and Frank A. Marston, for valu-
able assistance in the preparation of this book, and to John M. Goodell,
for many years editor-in-chief of ** Engineering Record/' whose con-
structive criticism and assistance in the preparation of the manuscript
have been most helpfuL To the publishers, tJie McGraw-Hill fiook
Company, Inc. whose work s|>?aks for itself, thanks arc also given-
Whatever its merits or demerits, the book is at least a monument to
co-operative effort and good will among civil engineers.

The preparation of this book has demanded an amount of time and
effort far in excess of that anticipated when the work was undertaken.
The authors have//inrried it through, however* because of their expe-
rience of the prkicl«ujll value of such information as is given in many chap-
ters heroin. *X» problems have arisen in their work, reference has Ix^en
made to th<^4»^,^)k ftijt'he hflp required, and if anything was found lacking
it was si*pt»jieih/*yiuHjjFtict3tal test has resulted in tlie repeated revision

The book is puliUshed, there-
book, but as the test of serv-
ice'ifrjo no of Jile.^'vot a thorough test of a liook on American Sewerage
Practice, constJ<*i'J comprehensively, the authors will l>e glad tn receive
from the reader'any suggested additions, changes or moditications wliich
will make the book more helpful, and to have any errors of statement or
computation called to their attention.

Leonard Mktcalf
IlAARifeON P. Kddt.
14 Beaco?^ Streft»

of larp^/j5Qi'tKjfRfW'j\»g\>j';oT the chapters.
ioT^p^^fi \i)i**[iuii{;ftiidi it is a ^'practicaF

CONTENTS

Page

Preface v

INTRODUCTION

The Lessons Taught by Early Sewerage Works 1

Surface-water drainage in London — ^London cesspools — Bazal-
gette^s plans — Early estimates of run-off — Drainage of Paris —
Reasons for large cross-sections — Paris cesspools — Water carriage
and dry collection — Early American sewerage engineers — Defects
of early sewers — Damages due to inadequate capacity for removing
storm water — Relative advantages and disadvantages of separate
and combined systems — Methods of sewage disposal.

CHAPTER I

The General Arrangement op Sewerage Systems 32

Influence of disposal methods on a sewer plan — Influence of Topog-
raphy— House drains — ^Lateral sewers — Branch sewers — Tnmk
sewers — Intercepting sewers — Relief sewers — Outfall sewers —
Inverted siphons — Force mains — Flushing sewers — Grades — Relief
outlets — Preliminary studies — Sewer sections — Depreciation of
sewers.

CHAPTER II

Flow of Water in Pipes and Channels 62

Molecular changes in water — Weight of water — Atmospheric pres-
sure— Intensity of water pressure — Laws of falling bodies — Flow
of water through pipes — Hydraulic grade line — Equation of con-
tinuity of flow — Development of formulas for flow in pipes and
ehannels — Bazin's old formula — Chezy formula — Kutter formula
— Determinations of n by different engineers' — SuggestVd values of
n for sewer design — American engineers' opinions regarding n —
Effect of variation in assumed value of n — Limitations of Kutter 's
formula — Hazen and Williams* formula.

CHAPTER III

Velocities and Grades 106

Ratio of mean to ma.ximum velocity — Ratio of mean to maximum
surface velocity — Ratio of mean to center velocity in pipes —
Transporting power of water — Erosion of sewer inverts — Minimum
grades and velocities — American engineers' opinions regarding mini-
mum grades — Examination of sewer design with reference to mini-

vii

viii CONTENTS

Page
mum flow conditions — Velocity in submerged sewers — Flush tanks
for dead ends — Hydraulic elements of some standard sewer sections.

CHAPTER IV

Measurement op Flowing Water 127

Measurement of flow in sewers — Discharge through orifices —
Weirs — Measurement of head — Different weir formulas — Choice
of formulas — Triangular weirs — Trapezoidal weirs — Venturi meters
— Float measurements — Current meter measurements.

CHAPTER V

Quantity op Sewage 150

Population — Assumption of uniform rate of growth — Graphical
method of estimating future population — Arithmetical increase in
population — Decrease in percentage rate of growth as cities increase
in size — Decrease in percentage rate of growth with age — Increase
in area — Density of population — Proportion of municipal water
supply reaching sewers — Rate of consumption in dififerent parts of a
city — Water consumption in cities — Fluctuations in water con-
sumption— Ratio of sewage flow to water consumption — Ground
water — ^Leakage — Actual measured flow of sewage — Variations in
flow — Relation of type of district to quantity of sewage — Classifica-
tion of areas — Philadelphia sewer gagings — Residential districts —
Mercantile districts — Industrial wastes — Estimate of quantity of
sewage from entire city — Provision for storm water — Basis of
design of existing intercepters.

CHAPTER VI

Precipitation • 207

Ferguson gage — Draper gage — Draper gage, old pattern — Friez
gage — Queen gage — Richard gage — Marvin gage — FitzGerald gage
— Helhnann gage — Exposure of gages — Absolute measurement of
rainfall — Relation between intensity and duration of rain — Form
of rainfall curve — Frequency of heavy storms — Phenomenal rain-
storms.

CHAPTER VII

Formulas por Estimating Storm-water Flow 235

Empirical formulas — Hawksley's formula — BUrkli-Ziegler's for-
mula— Adams' formula — McMath*s formula — Hering's formula —
Parmley's formula — Gregory's formula — Weight given to the
factors in the formulas — Use of McMath*s formula — Flood flows
from large drainage areas — Kuichling's formulas — Murphy's for-
mula— Met calf and Eddy's formula — Fuller's formula — Other for-
mulas— p]fT(*ot of snow and ice on floods — Records of flood flow of
streams — Frequency of floods in streams — Design of flood-water
channels.

CONTENTS

IX

CHAPTER VIII

Pack
Rational Mbtrod or EaxiMATiNQ Stokm-watbs Rcn-off in

Bawi&R DBt^IQ?! , 263

Ccmditions afTccting rate of run-<>ff^^ — Time of water in re&ching the
m^wcTH (inlet time) — Time of concentration — Hun-oflf fat-tor — Coef-
,^c'tsai of distrihutlon of rainfall — Coefficient of retention— Coeffi-
cient of retanUtion — Effect of storage in sewers and elsewliere —
Values ordinarily assumed for run-tjff faetor — Example of use of
. mtional method— Boston use of rational method — C<impariH4m of
dce»igns by rational method and by McMath formula --Additive
mcibod of computing run o^ — Basis of design of storm-i*'ater
•ewers In various cities — For how severe storms should drains be
rflcBigtied — Court ruUnge on damages from surcharged aewers.

CHAPTER IX

GAorxQ Storm* WATER Flow is Sewehs 301

Float gages — Hydrochronograph— Friezes automatic register — -

Builders Iron Foundry recorder — Pneumatic pre^ure gages — Other

rgttge» — Setting water level rec^irden? — Maximum flow gages —

lActual measurements of storm-water flow — Rainfall — Extent of

reii tributary — Characteristics of sewer district gaged —

CHAPTER X

Piric,

328

nUiriial pr»^s«urc on pipe— Pressure in trencher— Barljour's experi-

nettta — Haven's analysis — Iowa invejstigations by Mar»ton— -

rBtn*cigth of pipe — Prof. Howe's investigations — Standard require-

litieotii for cast-iron pipe — Manufacture of vitrified clay pipe —

llantifaeture of cemtmt pipe^Molding pipe in place — ^Praetical

iuetinnj? from tests and experience — Lock-joint pipe — Jackson

tpipc — Pannley pipe — Steel pipe — Pipe coatings— Cast-iron pipe —

WoodHiUivc pipe

CHAPTER XI

'NBT SbWERB .

— Egg-shaped sections — Catenarj* scntions —
I- Iv kt't-handle sections — Horse-shoe sections —
I r< t H lEt- —Parabolic or delta sections— 'Elh'ptirai sec*
-Unihape sections'—Rectangular sections — 8emi-circular sec-
t*etions with eimette— Df)wble and triple sections— Hy-
rlements of sections — Construction and available space —
of > ri and materials^ — Stability — Iinpen ioui^ness —

lydraub its and tables— Equivalent sectiontj^Empirical

fortntilits fof LiutkdctaB of arches.

382

m

X CONTENTS

CHAPTER XII

Pagb
Examples op Sewer Sections and the Loads on Sewers. . . .413
Plain concrete sections at Louisville and Borough of the Bronx —
Gregory's semi-clliptical section — Authors' semi-elliptical section —
St. Louis five-center arch — Examples of different types of sewers —
Wear on sewer inverts — Live luads — Proportion of loads trans-
mitted to sewers — Rankine's theory of earth pressures — Mohr's
method of determining pressures.

CHAPTER XIII

The Analysis op Masonry Arches 471

Analysis of arch by voussoir method — Analysis of arch by elastic
theory — Analysis of arch by method for indeterminate structures —
Analysis of 15-ft. semi-elliptical section by method for indetermi-
nate structures — Computation of stresses in arch section — Trans-
verse steel reinforcement — ^Longitudinal steel reinforcement —
Safe working stresses.

CHAPTER XIV

Street Inlets, Catch-basins and Manholes 513

Use of catch-basins — Street inlets — Catch-basins — Castings —
Manholes — Drop-manholes — Wellholes — Flight sewers — Special
manholes — Manhole steps — Manhole frames and covers — ^Lamp-
holes.

CHAPTER XV

Junctions, Siphons, Bridges and Flushing Devices 565

Junctions — Inverted siphons — Siphons — Bridges — Flushing from
brooks — Mushing manholes — Automatic flush-tanks — Value of
flushing.

CHAPTER XVI

Regulators, Overflows, Outlets, Tide Gates and Ventilation. 597
Regulators — Storm overflows — Leaping weirs — Silt chambers —
Outlets — Tide gates — Ventilation.

CHAPTER XVII

Sewage Pumping Stations 646

Comparison of different designs — Storage and screening — Pumps
— Types of reciprocating pumps — Piston speed — Water ends — Con-
nections— Centrifugal pumps — Efficiency of centrifugal pumps —
Setting centrifugal pumps— rPrime movers — Special pumps —
Typical pumping stations operat<;d by steam and gasoline engines
and electric motors — Economic size of force mains — Storage basins
on tide water.

Index 721

AMERICAN
SEWERAGE PRACTICE

INTRODUCTION: THE LESSONS TAUGHT BY EARLY
SEWERAGE WORKS

Amctrican sewerage practice Is noteworthy among the branches of

engineering for the proponderallng iiiiluence of exporieuce rather than

iixpt»rtin<*nt upon the developmeiit of many of its features, apart from

those c-oncerned with the treatment of sewage. Even the actual capacity

I of wewenj, something that gagings can determine, is far leas clearly

kaown today than is the capacity of water mains, while the cross-sect iona

of \ »ewers and the forma of accessor^' structures employed

nil i i;tr conditions in different cities vary widely. There has

bei&n, however^ a rather decided tendency' toward greater uniformity in

di^sgn in the last ten to fifteen years, keeping abreast with the growing

popuUr recognition of the financial and sanitary importance of good

iewera^ and the passing of the feeling that it was a bit indelicate to

•peak in pubUc of anything so unclean as sewage. Sewerage systems,

being nut of sight, were out of mind^ except to the few intrusted with

\ thw const Diction and maintenance, and even today the lack of any-

I ihiog above ground to show to the taxpayer makes sewerage work in a

cit; T.^ least appreciated activities. The strong feeling that good

[iKLM iih ia a valuable municipal asset and depends to a large

[extent upon good sewerage has been a Icailing cause of the wiUingnesa

iiycr« recently to embark on exiicnsive sewerage undertakings.

value of arousing public feeling toward sewerage in this way

the main lesson which the history of sewerage teaches. Until it

! bceaine a strong influence, sewerage work was concerned mainly with sur-

[Imte drainuge and the abatement of nuisances. The first record of a

1 1 Curt Merckel, the antiquarian of engineering, has been

1 in on an old Babylonian seal-cylinder. Layard*s explo-

IfttaociM rtjvealed arched sewers in Nineveh and Babylon dating from the

KVEOth uentuiy beforr* Christ* Schick and Warren have unearthed

I ioq^idrnibb infonnation about the sewers of Jerasalem, the works of

thin c\an in Grecian cities are fairly well kno^\^l, and the great under-

pimcid drainet of Komc* have been repeatedly described. We know,

I llwwrvf»r» thai thenc channels and conduits were not used to any extent

I by ine&as of direct cimnections to thetn from the houses, for the require-

I of public health were little recognized then and compui*5ory sani-

I

2 AMERICAN SEWERAGE PRACTICE

tution would have been considered an invasion of the rights of the indi-
vidual. Livy states that the Roman building regulations only stipu-
lated that the house connections were to be made at the cost of the
property owners. Public latrines were doubtless used by most of the
people and it is probable that the gutters were the chief receptacle of the
ordure of the city, which was washed thence into the sewers. These
mast have been extremely offensive when not flushed, for otherwise the
regular delivery of water for the purpose of cleaning them would not
have been so emphasized in the following notes by Frontinus, a water
commissioner of the city whose valuable notes of engineering work have
been edited by Clemens HerscheU

"I desire tliat nobody shall conduct away any excess water without
having receiveii my pennission or that of my representatives, for it is neces-
sary that a part of the supply flowing from the water-castles shall be utilized
not only for cleaning our city but also for flushing the sewers."

It is astonishing to reflect that from the day of Frontinus to that of
W. Lindley , * t here was no marked progroes in sewerage. The renaissance
began in Hamburg, where a severe conflagration destroyed the old part
of the city in 1842. The portion ruined was the oldest section and it
was decided to rebuild it according to modern ideas of convenience.
This work was intrusted to Lindley, who carried it out in a way that
aroused warm praise among engineers of a somewhat later period, when
the test of service had i)lace(l the seal of approval on the plans.

For instance, K. S. Chcsbrough, Muses Lane and Dr. C. F. Folsom
reported to the authorities of Boston in 1876 that Hamburg
"was the first city wliich had a complete systematic sewerage system
throughout, acconiing to modern idejus. How far that was in advance
of the rest of the world, in 1S43, when the work was undertaken, maybe
inferred from the fact that there arc no rt>al advanws in new principles
from that time up to the present tlay. The rain-water spouts were all un-
trapped to serve juj ventilators to the silvers; the street gullit»s were also
without traps, and there were gnitings for ventilation oiH»ning into the
streets. It is very rare that any of the latter are sourws of complaint,
inasmuch as the sewers are kept st> clean that then* art> seUlom any foul-
smelling gases. The grcjit feature in Ilamluinf, however, is the weekly
flushing at low tide by letting the waters of the Binnen-Alster flow through
the sewers with great force."

Twenty-five years after the sewers were completiHl they were found by a
committee of experts to l>e clean and alnuwt without odor.

The sewerage of Hamburg, while imlicativo oi an awakonetl public
recognition of the ntHnl of improvement in such works, was hardly the
result of any real appreciation of the value of sanitation but was rather

> Tjndloy was one of tho loading KntcUaih oinnmt^rs of hi* il;iy. UawHn<«on boinc Ji-i ■ :.!>•
rival at the hetkd of the sanitary branch of hU |>rt»f»»H»ii»n. Ho U*OHm.» thorvu^J-.'.y ul-. :-.t:r..?-.i
with Uerman work, however, first at Uamburc and later at Krunkfi^rt

INTRODUCTION

i^'TYsult of burliness shrewdness in taking advantage of exceptional
local conditions to plan streets and sewers to answer in the best way the
recognixed needs of the eommunity and the topographical condition.^.
Thehij^tory of the progresvS of mnitation in London probably affords a
tnon* lypicftl pirtureof what took place about the middle of the nineteenth
century quit^ generally in the largest cities of Great Britain and the
United States,

A statute* w^a« passed in 1531 in Henry Vni's reign* and amended in
that of William and Mar>' which afforded the legal basis of all sanitary
works of sewerage well into the nineteenth century. For a period of
about 300 years, while I^ndon outgrew the narrow limits of the City
proper and its adjacent parishes and became a great metropolis^ the
center of the world's commerce, sanitation was as little considered as
magnetism or the utilisation of steam for power purposes. The City
was better off than most of the metropolitan district, for it had Com-
missioners of iSewers elected annually by the Common Council from its
mendjers. They had power over all conditions relating to public health
and comfort, and had authority to appoint a medical officer of health.
But the City was only a small part of the metropolitan area, 720 out
of 75»0()0 acres in 1855, with only 128,000 out of a total population
of 2,500,000, and less than 15,000 out of a total of 300,000 houses.
_Outside of the City, the methods of local government were chaotic; in

tne of the parishes surveyors of highways were apiwint^d to do very

Btricted engineering work, and in eight there were Commissioners of
Sewers, apparently having powers modeled after those of the City but
less extensive.

This lack of central authority rendered a systematic study and exe-
cution of sewerage works impossible. As late as 1845 there was no
survey of the metropolis adequate as a basis for planning sewers. The
tiewers in adjoining parishes were on different elevations so that a
junction of them wtis impracticable. **Some of the sewers were higher
than the cesspools which they were supposed to drain, while others
had been so constructed that to be of any use the sewage would have
to flow upliilL Large sewers were made to discharge into smwll

rers." (Jepson's Sanitary Evolution of London.) The first engineer
ta make a comprehensive study of metropolitan sewerage needs in an
OJlicial capacity, John Phillips, gave thb testimony' of the condition
cf I^ndon basements and cellars in 1847 :

uitiiic to local draiiiACe problems had bepn paa^d in Oio reigcui o( Henry III,
Hrnry VI I.
y^e ronsiderrd too fanciful, % atnitfmttnt publlnhpcl in 1S52 by the Gcaeml

' Litbof«i K>\ the Gi'Q»nJ Board of Health rotioh illiicm prevAikd Among
th» <-li»rfc», iintii on ime wrtiirum foul miti^IU urii^inc more sfvervly ihan hud before biirn
noticed* the tiiit^ of tb* fauj!id«liriiui wtt» nxjuimiaedf when it whim disrovertHl th«t tlifrre «raro
tVA fnfery Urto eeaapooU lmni«di«t«ly bcno^th th« Board'* offices. I'his \b the deM-ripUoo

4 AMERICAN SEWEHAGB PRACTICE

*' There are humlredsi I may aay thousands, of hoitsait in thb metropolis
whioh have no dniinage w{mte%''er, and the greater part of tliem have stinking,
overflowing cesspools. And there arc nUo hundreds of streets, courts M\d
alleys that have no sowers; and how the drainage and filth are cleaned away
and how the laiserablc inhabitants live in such phioo« it is hard to tell.

'*In pursuance of niy duties, from time to time, I have visited very many
places where filth wa.H lying scattered about the rcjoms, vaults, cellars,
areas and yards, so thick and so deep that it was hardly possible to move
for it. I have also seen in such places human beings living and sUx^ping in
sunk rooms with filth from overflowing cesapoob exuding through and
running down the walls and over the floors, . . . , The effects of the
effluvia, stench and poisonous gabies constantly evolving from these foul
acGumtdations were apparent in the haggard, wan and swarthy oountenances
and enfeeldi'd limbs of the poor creatures whom 1 found residing over and
amongst these dens of pollution and wretchedness/'

One of the main reasons for the backward condition of the sewerage
sv'siem in London for many ye^irs was the absence of authority to com-
pel landlords to connect their houses with sewers, .so that even the
residences of the wealthiest members of the nobility were likely to bo
located over one or more cesspools, some of which were occjujionally
of enormous size. Even in Westminster, very little use was mmie of
the sewers in some of the streets. '*8o loug as the owners get the rent,
they do not care about the drainage," the Commissioners of Sewers
reported in 1845. It was not until two years later that the first act
was passed making it compulsory to connect houses with sowers.

lu 1S47, scared by an outbreak of cholera in India, which had begun
to work westward, a royal commission was appointed to inquire into
sanitary improvements for London. This body reported tliat the
sewerage of the entire metropolitan district should be handled by a
single board, and in 1848 Parliament followed this advice and created
the Metropolitan Commission of Sewers. That body and its succeesors
in the office unfortunately failed to measure up to their opportunities;
they produced reports showing clearly the need of extensive sewerage
works and other sanitary improvements, bmlt the Victoria sewer at
great expense, which fell into niins not many years lat^^r^ but did little
more. In the summer of 1848 cholera wa^* discovered in London and
before the winter was over it claimed 468 victijns. It liroko out agnln
in the spring of 1849 and before it ended ttl>out 14,600 deatlis were
recorded, as against (5729 in London in the 1832-33 epidenjic.

In 1852 aholcra ligain appeared and in 1853 it slowly gained a foot--

qC hr>u«OK »f wtilrh it in grnrraHy n*puTi<?i! by ' > .!■

drntncft ami in kikhI ntmcjitinn; litjt H iimy h*

Any Uou»c without u thorough <»rnmin4iUoii of •

Wnf. iyphviii fir uttJitric. Imvp ocruirc*! iit»i>»g)^t pcrsifOa U'

{• it wiffi for thcmv whr) valur tliHr uwu hfjiUh lo r«mMlu ut

AfnlQftUofi, tior utitit th« c>«wit>oali tifit r«fut)v«<l.**

1 uji4 uthr
i it i» Ah»i>

y tiTf wHl
to Uke
of

i u houNtf,

INTRODUCTION

In 1854 it ran its terrible course, claiming a mortality of 10,675
in till? last half of that year. The connection between a contaminated
water supply and the rapid spread of the disease was clearly shown,
bul it was also apparent that the hlthy living conditions in most houses,
due to the absence of effective sewerage, was a great hindrance in com-
batting the scourge. In 1855 Parliament passed an act '*for the better
ldt«tl management of the metropolis;*' this laid the basis for the sanita-
tion t»f London and provided for the Metropolitan Board of Works
which soon after undertook an adequate sewerage system.
in this connection a brief mention of some of the features in the
rly development of the London sewers will be of value as showing by
stnuit the im|X)rtance of the progress in sewerage in recent years.
] ill answer to an advertisement, the MetropoUtan CommL*-

nifT .nra recreived 116 different schemers for abating the nuLmnce

dUA to sewage in the Thames; none was approved for execution. Pkns
for intereepting the sewage and conducting it to outlets below the city
bid bwn sugKcsted many years before. It was not until 1852, when
J, W. Baialgetle became chief engineer of the Commission, that any
beginning was apparently made in formulating policies, although at
tea^ two engineers of high standing connet!ted with the local works
oC oertiiin suIkIi visions of the metropolitan district had been making
yiJuable studies. Baaalgctte seems to have been possessed of the exec-
utive ability previouiily lacking; he developed plans (or interception
fciiUlively and tben worked them out in detail in collaboration with
W. Haywood, the unusually gifted and higldy respected engineer of the
Ci* nssioners of Sewers, who had a thorough local engineering

•^1 lud was responsible for many of the basic assumptions upon

whidi I lie plans were pre[)ared. But no action was taken on these plans
,il the MetropoUtan Board of Works appointed Bazalgette its engi-
and he had been compelled to uphold them agaimst lay and engi-
iiiH*nng tTitici?^m for several years. The works were not actually
undertaken until 1850.

The old ."H^wera were frequently the covered channels of brooks. The
(iUo»l wfw Ludgate Hill sewer, of unknown age, hut built prior to Fleet
Stn?«fl H(Hv**r, whicfi was constructed in lliOS and was an open channel
fr/r This sewer, formerly known as the River of Wells

or irne (now called Holborn), was fed by several springs,

lad wiui originally a navigable waterway from which people were sup-
|4M with water. It was not covered until 1732. Wliat eventually
bnimite lianelagh -sewer wim a brook rising in a spring at Tye Bourne
And even as late an 1730 it furnished wuttT fur the Serpentine, the
faiouUji pond in Hyde Bark. In 1855 the total length of these old sewera
[ini lUH miles. Up to 1815 it was contrary to law to discharge

6

AMERICAN SEWERAGE PRACTICE

sewage or other oftensive matter into the gewers; cesspools' were regardeil
Bs the proper receptacles for house drainage and sewers as the legiti-
mate cluiunelK for carrying off surface water only. The ces^jwols were
cleaned by private contractors at the expense of the property owners,
and conwqucntly the frequency of the cleaning depended on the cal-
lousness of the owner or tenant to complaint and nuisance. Concern-
ing the removal, the General Board of Heall h reporte<l in 1852 as follows:

"It appears that the quantity of cesspool refiifiCf including ordure and

other animal and vegetable nifttter, is from 1 to 2 cu. yd. per house per
annum; and the cost of its removal in London (including openings and mak-
ing good the ct^HJitpool, iind cartage out uf town) was stated by (infractors,
and proved up<m a house-t<>house inquiry, to be on an average^ about
20e. per house. When cfienp cesspools tire miule, from which percolation
is not preventerb thp injury to the* foundations of the houses would more
than make up fhc difference. In many country towns^ where night-«oil is
kept in ahallow uncovered oiU (calleil midden-holes) the cast of emptying
is le^s than where dt^ep cesspoob are used, but although the emanationsi
ajB being more diluted, may be less noxious than those arising from covered
cse>8spocjls» the sight of the expcjsed ordun? is offensive and doitrading, and
the open midden-steads are in other respects serious nuisances."

It has been mentioned that the pollution of the Thames w:<s a caune
of public prote:^t in the middle of the last century; it wils aggravated by
the manner in which the sewers discharged their contents. Bazalgette*a
description of it is worth quoting as explaining a feature of outfall aewer
design which is sometimes overlooked at the present time:

"According to the system which it was sought to improve, the London
main sewers fell into the valley of the Thames, and most of them, paissing
rmder the low grounds on the margin of the river before they ri»ached it,
discharged their contents into that river at or about the level, and at the
time cmly, of low water. As the tide rose^ it closed the outlets and ponded
back the stowage flowing from the high grounds; this accumulated in the low-
lying piirtions of the sewerst, where it n'runincd stagnant in many crises for
18 out of every 24 hours. During that period, tlie lieiivier ingredients were
depoaite<I, and from day to day accumulnted in the seyvers; hcMidcjs which,
in titru^ of heavy and long-continued rains, and mure particularly when
tlicst* occurred at the time of high Wftt4?r in the river, the cKisc*d sewers were
unable to store the increased volume of iicwage, which then rose through tU«
house drains and flooded the basements of the houses. The effect upon
the Thames, of thus dischiirging the sewage into it at the time of low water,
wa» most injurious, because not only wus It carried by the rising tide up

> "WKat ftre trn Its in tbo UuiUhI SuUii lUdct from the T ' i- la

thtii pitrticidftr; tin fAcuvntrd pit* in tUr HulNiiji], jiUiiiAuu-U i nry

In '- ■'■'* ■- ■" ^ fi«uii0i1 out until tK" ■tirtouiniinK ■ »rK

Is! . „ .' J out rit nroiwi-r itit^irvaU,"* (R^s 'Ifi*

ilirik^HHI

TNTRODUCTWN

ihe fiyrXf to be l>rought back to London by the following eT>b-ti<io, there to
mix with each day's fresh supply^ the progress of niany days' u(!(nmtulation
towtiTfi the max being almost imperceptible — but the volume i»f rhr puro
w»ti*r in tho river, l>eirig at that tiioe at its iniMimum, rondorv<l itc^uite in-
Cipabtti of UiJutitig and diainfectiug such vaat masses of sewage/'

In designing the great intercepting and outfall sewers to remedy tliis
Comlition, Bazalgetie adopted a mean velocity of 2.2 ft. per second as
•det^uatc to prevent silting in a main sewer running half full, **more
espwially w^heu tho contents have been previously pa^ed through a
pumping station." The computation of the house sewage was based on
an ftveriige density of population of 30,000 perscjns per square mile
except in tho outlying dwt riots, where it wa.s assumed at 20,000. The
aewage vrns estimated at the assumed water consumption, 5 cu. ft.
p*T cApita daily. '*Thi3 quantity varies but Uttlc from the water
supply with which a given population is provided; for that portion which
babsorlHM^l and evaporated 18 compensated for by the dry-w^eather under-
ground leakuge into the sewers," One-half of this sewage was a^ssumed
Ui flow otX within 0 hours. The storm-water run-off^ for which provision
wa§ made was a rainfall at the rate of 1/4 in. per day received during
the ft hours of maximum sewage flow, with overflows to discharge
tbe cxccMJi due to larger amounts through some of the old sewers di-
r, clly into Uie river.

It is not surpriijing, in the light of pre^sent information summariised
In on© of the following chapters, that these estimates proved too low*
and flooding took plaee in low-lying districts. As for the average

~ ,1 fvefy yt*ar« exceptional cjutes of heavy and violent rain stortnii,

•- J I in., ami sonietimet ©voo 2 in,, in an hour A quantity (N]uitt to

|]> •>• ui 111' b of min in an bour, or 1/4 of an inch in 24 hours, running int^j tho

^ I Dcru|iy lia much spiKn? aa the niaximum proflpective flow tti »rwaifc! to Im»

1' •• Ui,it, if that qu(\ntity nf min wtTc included in the int«.'ro<*i>»init »t*w<?r», rhry

liGuin of inaxiiiium flow« be filled with an equal Tofunit^ of t«wag9* and

a' IS houm additional ipacit vrciuld be reserved for a larger uuautity uf rain.

t.i}|f>(»itito r-oniiiderniirfn, and allowinj; for tbe ab«f ruction due toe^'apm^

"H. it b probable that if the towers were mnde cnpitble of carrying off tk

t' ' I a niinfuU of 1/4 in. per diiy, during the 6 hours of the intutituum flow* therms

• 'fior« thrtri 12 diiyM in a year an wbinh th« mewerH would he overchnrfted, iind

'' ' -* - ' ttit during sui-h dny*/* BnBalgrrte. Proc, In»t, C. K,, 3i«iv* 292.

1 ruinfjdl pruvidetl for wi^a :i{H,(KiO,iXK> imp, gut por d»y. Th«

ti*ii srwvrH was, however, niad«^ h^rger than thin nniount, u« it \m n

• t, ov^lng to iho flut'tuutiug How of sewnge nl dlfferenl hoiirt of iho day.

I if> total quantity flown o0 in H bourn, and aa Bgurea in the abovo tabloi

(;> .1*1* tfal. of sewage and gHii.tK KJ,00i> imp. gaL of min-wat*^r.— M, * EJ givi*

|i <. <•««• «itri»ad ovf<r the whole ii hours, provi^oo h»d to \m modie and waa made for

>*ar«4.-. 'of oewagr Rivim in thcne i«(ldrs« » » Thii provision fot

Aarikan uto the Thames by meana ol tbe old aewors nonld not h«i

m^li/imt' '' - ilrvudy I>mmi pointed out iftnt theo^* old ai.'werii vn*tii

J ,. titoe Iwfon* and aftnf high water, i*nd, ihcrtdore. tho

lit •om*» time on ett^-h aide of low wftt4*r, untons in anjii

<A«r^ ciipttble of boing put under eueh a prviKnire ai would uv«.*riM»fue tho

>i ih» tidal iinodl/' Maurteo Fttatttauhco, *' Main Ominage of London."

AMERICAN SEWERAGE PRACTICE

mminmm velocity selected, it was higher than that recommended by
aome contemporary engineers. Wicktrtced had reported experiments
showing that a bottom velocity of 16 m. per second would move heavy
pieces of brick and stone, and a velocity of 21 3 /4 in., would move iron
oringa and heavy slag- John PMllips advocated a velocity of 2 1/2
ft* per second. Professor RobLson said in hia ** Theory of Rivers"
that a bottom velocity of 3 in. per second will take up fine clay such ns
potters use, 6 in. will lift fine sand^ 8 in. will lift sand :ia coarse as lin-
seed, 12 in. will sweep along fine gravel, 24 in, will roll along 1-in. pebbles,
and 30 in. will move angular stones of the sis-.e of an egg. These state-
ments of the Ktate of knowledge in 1S50 show a tendency to under-
estimate reqmaite velocities to prevent silting, and, taken in connection
with the underestimates of run-off and their unpleasant conseciuences,
illustrate the great desirability of adequate experiments to ascertain
unknown facts essential for sucoeasful design^ before spending great
sums on construction.

The questionable cliaraoter of the information available for design
was recognized by a number of engineers, as the following reraark»*
by Sir Robert Rawlinson indicate clearly:

'*To talk of a formula for main sewers, devised and drawn up from any
one set of experiments, would only t^ind to mislead young engineers. There
were no two places which required precisely the same treatment. . . .
The proper mode of proceeding was: before att^^mpting to fix the dimensions
of main sewers, to take the area to be operated upon as it existed; to consider
what nature had previously done with that area; then to corisider the special
duties whieli the sewers had to perform, and .apportion theni to the water
supply and to the probable increase of the population; and if the dimensions
adopted were calculated for passing off three times or four times that volume,
the Engineer would not be far astray in hia calculation" (Proc. Inst. C. E.,
xxiv, 317).

Prior to Haywood and Bazalgette's work on the London intercepting
sewers, Phillips and Roe were prominently before the public aa sewerage
^experts ajul among English-speaking engineers Roe's Table^ was used
or miuiy years in selecting the sizes of sewers. As a matter of his-
torical intcrei^t, for it was used by many early American engineers, it is
reproduced in Table L It was acknowledged to be entirely empirical

1^ It iff evicltsai ilmi 8ir RotMtrt whh apealdniE n( bh* wurs tor booiM tlmiTiiicu otdy. tie wji« iUii
lc>ii(icr in tho dpvHopmcai of mrxlt^ra sowerKge p(iictic« mad tixeirciiiKl it g.nu% ioAuvnoo
ovor ibc cnsineers ol hU day »jridi itit public.

" Rou'b Tiiblo wna not nrrcpl^d t»y •om«* conteniponiry Ixinr!- ...;^-..— .....i ;.- 1H66

W. JlAywnod, *.»nifiiiof*r of tho City, who ri.»fnni»)«Mi tof half n cvsi on

E(iicU*h muniripiil t*ii«iui-« i inif. oiiril^ii at a tnifctiiiie of tht* In-' > _ i <'«

that there wcfr tin rttllm f Liiftilon iKSDiitrii in <3itt*i«tnr4» ittid timi Ua kmti uiivcr bccfi

nbU* to obtain any at^rii < aion rrtgiirdina mmh wuric from nilhDr PhilhpM or littn.

He etnt4<ti thitl hu ha«J hccii IoIvchI Ui niuk« 4>KtMi»tv^ri aHClitc* Id (Hiiitequi>D<%i and tH«<««
whowrci tbftt nhfiut hull iht^ M*wti<ti I'otuiittt divUy from the 11 B4iuttr« iuXIcs iribut«ry io the
EBging tlAUt^iu pMflcd off btiwvwti U 4« n^ »utl ft r. u.

;

INTRODUCTION

s

sml W1W baisetl an Roe's observ^ations in the Holborn and Flnsbury di-
rmatcA of the London sewers during more than 20 years, he said. Roe
anc 'i some testimony that the particulars from which the table

waa 1 filled upward of a hundred memorandum books. In

acniie ciism the records were asserted to relate to observations carried
during the whole period of heavy rains, being commenced as each

xvnx\ began and continued until its efifect had ceased in the wewers, the
lepth of water being taken every 5 minutes and the velocity of current
H^UhI at every dt'pth* In some instances the observ^iitions were con-

inacd day and night for 2 years and in others for periods of a few

Tjuits 1. — Rob's Table, Showing the Quantity of CoveaBD StrnFACE

rtlOM WHICH ClRCtTLAH SbWERS (WITH JlTNCTlONS PROPEKLY
COXXECTEDJ WILL CoXVEY AWAY THE WaTEU CoMINO FROM

A Fall of Rain of 1 in. in tub Hoiir, with
House Drainage,

^

24

30

35

\^

GO

72

•orf*

wttm

Aorei

wcTtm

ftcr«fl

IMirei

Lmrel

38f

m

120

277

570

1,020

t in 480

43

76

135

308

630

1417

I ill 240

60

87

155

355

735

1,318

r in 160

m

113

203

460

950

1,692

lib 120

78

143

257

590

1.200

2,180

t in 80

90

l(i5

295

670

1,385

2,486

I in 60

115

182

318

730

1,500

2,675

- - - f.r of

u ,

M

108

120

132

144

•nres

mtt^

ftwes

MFM

aerffs

stores

IJBVA

1,725

2,850

4,125

5,825

7,800

10,UJO

1 in 480

1,925

3,025

4,425

6,2.50

8,300

10,750

1 in 240

2,225

3,500

6,100

7,175

9,530

12,4(K> j

1 in im

2,875

4,500

6,575

9,250

12,300

15,950 '

1 in 120

3,700

5,825

7,850

ii,a50

14,700

19,085

lif! 80

4,225

6.625

liti m

4.550

7,125

Um§ — 0F '"hmiJH" tJiTviirngft" \ivm rnriiot rain-w«l4:r from roofa jtmi ctmrta. It isdiJTj^ult
) 0wm lllw* tt»t4» (»l ttk» firai pubtififttion of thin tablo, but it wa* probably botwoQo 1840
MM tfrUt

I in w*vt*ral yciira. Roc laid much stress on curving all janctions,
riii^ tt 30-ft, radiu?*; where the ju Fictions lu^c made at ri^ht angles
rtuccl iwing larger sowers than tlione given in tlie table, a recom-
itioA that ^cms to have been generally overlooked. Another
to be eooaidercd in u^iug the table he stated thus:

10

AMERICAN S EWE HAG E PRACTICE

'*In applying the t^hle to locialities wher© the tndmation is greater than
that of the Holhorn and Finsbur>' divisions, a mmlification of the sizes of
the sewers will l>e required; for instance, in une case that (»inie under my
notice*, when tht; genoral inclination of the aurfaee of the streets waa about
1 in 20, the greatc4*t flow of water from a thunderstorm came t^ the Hewer at
the rate of one-third more than it did to a sewer draining a simihir fall of
rain from an area with a general surface inclination of 1 in 132/*

It should be said here that sewerage progress elsewhere in England
was apparently less opposed tlmn in London. In IS4S Parliament
passed a sanitary code applying to all parts of England and Wales ex-
cept London, and in 1855 it enacted a nuisance removal kw for all Eng-
land; those laws were the basis of the subriequent sanitary progress
otitside the metropolis for uiany years. It will be observefl, however,
that the development of sewerage undertakings in that country was a
direct result of the awakening of the people by a succession of epi-
demics of cholera, for progress did not begin until that disease had twice
terrorized the country within a short period.

The present sewerage system of Paris, like that of London, was in
augurated a.s a result of a cholera epidemic. The system is unique in
some ways, although in its early days the Parisian sewers were doubtless
little different from the conduit^s enclosing old brooks or receiving storm
water which were constructed in many large cities. The Menihnontant
sewer, mentioned in a record of 1412, was of ilus type, and remained
uncovered until about 1750. It intercepted the drainage of the streetia
on the northern slope of the city's area lying on the right bank of the
Seine and was called the '* great drain*' [grand cgovi or {gtnd de Ceinture).
The part of the city on the left bank of the river was drained by open
gutters leading down the centers of the streets to the river.

The tirst att^empt to study the sewerage needs of the city compre-
hensively was apparently made in 1808, when there were 14 1/2 miles of
drains w^ith about 40 outlets into the river, and dvu-ing the next 24 years
about 10 1 /2 miles more of drains were constructed. In iH'A2 the ravages
of cholera awakened tlie authorities to a partial realization of the oity'a
unsanitary' condition* The fallowing year a topographical sur\*ey was
made, and with the aid of the maps based upon it, live systenis or divisions
of sewerage were planned, based on to[)ographicnl features of the
territory rather than on the administrative boundaries of parishes,
which caused so much delay in the drxelopment (»f rational drainage
at London and have been harmful in the United States. Many of tho
low-lying streets ahjng the river were raisinl at tliis time above the level
of any known flood, which indicates that the work was reuardwl a ' drain*
age rather than house sewerage. The regulation of the Htreeta waa
attended in some cases by the reconstniction or entire abandonmciil of
tbtj old sewers in thetn. One of the most interesting features of tho work

rNTRODUCTION

11

i ill© chnnge in the cfoss-ser^tion of the streets from concave to con-
st for rmsans rxptfiined by H. B. Hcderstedt:

**W*th regard U» the onn version of the <H^nciive surfaces oi ruads into

oocivcx. It miiy be shu>\n to have formed an important part of the drainage

Ofit. Aitainst hollow roadd, there were always complaints. The old

I etinst.*ititly cut up t he roadway with cross-channels or ^uttera. Another

nbjcct hiui bo(*n considered, however, in making the change, the certainty

|>f frt'^^ing the r«>ads n>ore readily from rainfall. In the concave roads, iron

nttitgs were set on the top of small working shafts, buiJt on the crown of

Jw driiin-arch, The^c iron gratings frccjuently became cloggi^l and the

of the water was impeded to such an extent that raitiied planka were

tionnlly used to enable foot passengers to cross the road» the vehicles

IwhUc being compelled to travel through a sea of mud. The old road-

lhaA\, in many place*, tobe lifted to obtain sufficient headway for the

attni-eteeci drains; the vahie of the convex roads, hh affording an

height, is therefore obvious.*' (Proc. Inst. C. E., xxiv, 262)*

Tfaa new sewers built in Paris from lS^i3 onw^ard were made 6 ft,
r mora high wlierever possible, in thu belief that the workmen employed
cleaning tiicm would discharge their duties more efficiently if they
A ithi>ut b<iing forced to take unnatural povsitions.* Toward
'^ sewers were given a minimum height of o,5 to 5.9 ft. with-
ut exception, and a width of 2.3 to 2*6 ft. at the springing line of the
ch^ the width lit the invert being a trifle less, **Tliese dimensions
too Bcanty; for getting about easily at least 2 m. height and 1 nu
|t^ 's*ded." (ffumblot.) When it became necessary later to

of these small sections to receive water mains^ the top was
iilcfM?d out on one side (sonietimes on both sides) w^hiie the lower part
left narrow, thus producing those sections 8ha|>ed something like
I«lt<!r P wdiich have been the subject of strange comments from
HUB r with their nrigin.

AUIiou^. has been a great deal of criticism of the large Parisian

it has generally faUt^d to take into account that the sewers of
^■dly havo bwti built wdth a view^ to removing street refuse as well
And niin^water. There are no catchbasixLs on these great
ilnkm <» that ever>' thing entering the inlets, and not caught in the littlo
joutpunded in s<mie of them, passes directly into the sewers.

I^Obt »b«jh>oi ioT m«kljiic the •miiH«xit cIjim ot pubUo seven in Pari* bo much IsfKQT tluii
> in ev^tty iikhitt mty in the prtietioo which, till wHhln lQy<7itrs. oxijiccl only lber«, u(
mt mtimm In thum *' (K. H. Chrabrou^h, 1856, > In communtiuc on ihc topo-
'f " a r«?pnrt in 188f> Umt the flal portion*

vt'fv ufidfrmined by old nuurri«Mi» no thw*

^ _ i^fl, iind it. vrnH partiriuldriy dMirrtbtc to

«*p llv ^ESi^ il<i be ubnorv'trd couHtujitly. Trh-irmph

. *>l t>i#r--.-.tM' Ti J Htrlitig niuil wt^rv pkcrcl ill thonewnrson

I liiiiiinn iiriil mniritf^nnn««r(. Oaa mAin« wifn rnhn plaood in tt few
M« l(Mi to tilt' jibiiiidonEuvlil ot thiA iirsietico.

12

AMEHiCAN SEWERAGE PRACTICE

The streets aro cleaned largely by waaliiug them with hose streuii
The street Utter m flushed into the aewera and i-* swept down the latter
by atorm water and by the sewer-cleaning gangs into the larger sewers
or collectors, 8ome of the sewer sludge is removed through manhole>s
but most of it is flui?hed tlirough the collectors or interee[)ting sewers
by the batenux vnnnes and wngims varutes^. These aje boat^ or cars
provided with wings reaching nearly to the walls of the channels. The
wings dam up the sewage somewhat and it escapes around their edges
with a higher velocity than that of the ordtnar^^ current* In this way
tlio sludge La stirred up and carried along tiliead of the^e cleaning devices.
Other means of cleaning are also employed, but it is unnecessary to
describe them here; the reader intere-st^d in the subject wiU find the whole
field of the design, construction and management of the Paris sewer
sj'stem described in Hervieu's ''Trait*!' Pratique de la Construction des
Egauts" (Paris, 1897), A large part of the sludge is forced ak)ng into
large chambers on the banks of the river, where it is discharged through
chutes into barges which remove it to various places of disposal.

The chief feature of this work inaugurated in 1833 was its recognition
of the principle of interception. Longitudinal drains of large section
were laid out parallel to the river and only three of the forty old mouths
of independent sewers were left in ser\'ice, the remaining systems being
made to discharge into the intercepters. The rain-water falling on the
roofs was taken at first through leader* to the gutters, l»ut later was»
diverted in some cases to the large *' house drains," with sections big
enough for a man to walk through, connecting the houses with the sewera
but used only for delivering waste water and not for excrementitious
matter. The latter was discharged for many years into ceswpooLs, one
frequently answering for an entire block of houses.

*'The Pariaiana committed the fatal mistake about 1820, of insisting by.
ordinance on cesspool construction. It Vkim recorded thul the whole suhsnil
of Paris was on the point of l>ecoming putrid with cesspit nitttter, tind that
the ordinnnce W7is passed in consequence. By it all cc*<spil»» as inaftcrs of
private construction^ were abolished, and the construction of cesspools on n
gigantic scale was uudert^iken or directed by the municipality, tind all persona
thereafter building houses were rtbliged to construct •hermeticHlly-ecRled ceas-
pools* after a municipal or royal plan which had been devise*! by the govern-
ment engiaaiTS of Knmcc. Into those cessjMjuls effete matter from water-
closets^ grease and washings from the sinks, and such rf^fusc wastobodis-
chargtMl/* (8ir Iloberi Uawlinson, Proc. Inst. C. E., xxiv,3l8.)

The oe^spools finally became no offensive that the nostrils of the
Parisians were plagtied aofl a new system of • wa?» at

ingly developed. At tliat time European sanit^i r divide* I

two schools, advocating respectively the **dry " and the" water carriage*'
methods of collecting excremeoti tious matter. I n the former this mat tcr

INTRODUCTION

13

lectod And rt'inovctl in pails and in tho latter ib is fliLshcfl into the
The former is still used in a number of European cities, but aa
lit 1- i filoyed in the United States it is necessary hero to g^ive only

IlKi ix brief aeeount of it, abridged from Dr, Ilering's report on

|Kuro]>esia sewerage, mentioned laWr in this chapter, A complete sum-
[inar>* of the subject La giv^en in Baumeister'a ** Cleaning and Sewerage
of Cilice/' where the methods of cleaning cesspoob, the equipment for
I **ciry *' collection, and the dispoml of the contents of the paik are treated
I with a detail unnece:^aary to repeat for American readers.

W-itor wirrinRP was opposed by European chemista, physicians and agri-
fcul <n of a fear of contamination of the soil by leakage from the

'Ic pollution of bodies of water receiving the sewage and
iihle nui«iinees if not actual dangers where the sewage was distributed
|4itrt<r land. Engineers were generally favorable to water carriage. Dr.
jFpttefikofer, the famous hygieiiiat, was at first an opponent of it but svjb-
■Kl^ifritly became an advocate.

l>ry removal ticcomplLshed its object aatiafactorily, either by an immediate
innd ' li disinfection with subsequent removal at convenient intervals

I or I rary wtoruge with frequent removal before decomposition could

I be n-'inlttrt-ni injunout^.

There were t wo c«om mon methods of disinfection , Tl>e first was the partial

I ftbHorptiein of the sewage by dry earth, peat, chiircoal tmd like matenala,

I which acoi?Jenited its decomposition and diminished offensive odors. The

lt|ie(»ffid waa the addition of carbolic acid, chloride of lime, creosote oil and

'Otiicr ehcfDioids to the sewage,

Wlinw ihnn:' was no disinfection, the excreta were cuUected in a "pail,"
' ^ in l*Vance and Umne in GeTmany) made of iron or oak and
'liiQii with a tight lid ha%^ing a slet'Vf fitting closely around
li** It' soil pipe. These pails were oolleeted at intervals of a

dbi> I dean ones substituted for them. Where the system was

•OTi >st 8ati»fact/orily , the pails were r(?moved In wagons with tightly

^» rind were carefully cleaned after being emptied. The contents

|»rr tly used for fertiliiKing purposes,

Ti.- -M > nvstem, tci compare favorably with the water carriage system,

linittt b« r«»Btricted to (1) small towns, on account of the expense of cartage;

I itT regular cxchangt? of the pails can be enforc<Ml with almost

, which is sehlom found outside of a few Euru|>eau eoun-

,.iy ki^Llluigs where water-closets cannot be used; (4) localities where

would btj vpr>' exjx^nsivc; (5) where the waste wat<rr can be led

I nurface of Uao ground without causing offense.

I WQH an unusual modification of the pail system employed for sonn'

Puns afti!r the ix^sspoiils bceanic toi> offensive, The engineers of

"-^r*' * •+*ly ailvocatett of water carriage for removing fecal matter,

t popular apposition to this although the large storm-water

reri' :ivail;ihlc ff»r water carriage and their rn^ntents were already foul

efu^ Wmshed from the i^tn-ets* Accurdingly a foase filfre was tem-

"ujied to educitttc the publir. It was a cask of 20 to 25 gal. which

H

AMMMiCAX SEWERAGE PRACTICE

I it thnjugh the soil pipo but fM*miitt<»d the ^cakpe

tU \h» ltem*klt tolo lltoe aewr. As the liquids are i\\e [Tumi puttx^rtble purls

lit Mit.* (^viTi^^ift^ «on# santtmry fC!%in was made in thi^ \vn\% atid ah sootx as

:>im alittlf^i the pail and it a connections were removed and the

:*.*i ^^^'%• vvrdiM^ttcicI with the hous«» dnvin by a few feet of pipe.

Tito «Wf^3f stmem^ works in the United States are almti^t unknown.*

*lNh^ «ltla^ J^wariPwfi •ewfTaiff rnKiriJPore of not4» were fiwt cngaRwl on sweh work by

ft^i* *- fc^* .».'liiAtit»n Ttjf Ibt is hvadecl by E. 8, Cbesbrou(?h» who Wtta born in 1813

ii'»*» • chainman on railroad aurvpys whfM» he was 15 yrnn old,

hI enyinr^cnnjE pomtions until 1846, whon he bccAmr ehlt'f fnuturffF

^ h > u »»( thit BoirtQii m'ftter works. He wan rrluctti&t to nocept thiM work

w» * >>f fftmiliarity with AQythiuK but milroad cngint^onnK, and only undi^r*

Mitx* that J. H. Jcrvia would art as eonaultine pnvinevr H«t remniticd

U(v»im«s rity enfinf*T of Bo»ton, in lS5t'), ttnd thus first b«c»m« int#r-

' - -iijruHl in ]HSS lo W^omc tht» onsdnoiT of Ch'* Chiinft(f»i Sowcrajpo

rtit thts office he publiahcd in 18.58, a voluminous tvport on im-w-

: : : ' ully impunHoi Anipriran cTpoflition of thp »ubiuct. Hia pliinit for

:\i* •MWtra wr^ro adopted nnd thjit rity wa« the fintt important plnctt Lq the i^ountry

"u ihc systeriiAtio i^ipfution of n L^ompn^hrnsive ftcwerniie sysUrm, This ustub-

'ppuintUm as a Appdalist and he war subiHiqurntly consulted in eonntrljon with

, roibirm* by Boston^ BurUogton, la.* Chalta&oojctii Des Moines. Duburiiir. Mi^tn-

|.lii«. \ I VI llavfn. Peoria, Providence and many Bmaller places. He waa the eighth prcfident

lit the Atn«'ric<>ati Society of Civil Enainram.

Mo«ir«i l^tae, like Che«ibrouith, was a ntilrothd t^ncin^er la early life. Ha wa« bom in 1M23
»nU was icmduated from th« Tnivenuty of Vorroont in 1845 u n civil entiiieer. lie woa
ffiffAffed in aliernatinic periods on railroad engincerinK and aa a teacher d/>wn to about 1857,
when hft became principal tkasistant eogineer of the Brooklyn water works, un<lfir J, P-
Kirkwood. and finally sucei*eded him. In 18fl9 he became m partner of Cheabrough in
CMmtn find thus mni^ into loueh with scwermiti* work for lh« first ttmo. His moat im-
portant plans for sewers wer** thn systema for Milwaukee and Buffalo, but hu nbo fuf-
lushnd plaufl for n number of anudler plaees. When be died in 1A82. he wns ^enr^incr its city
engtne««r of Milwaukee, a plafw ho had previously held from 1^76 to 187S. While Itia
promiucnce us a dei«ign<«r of water works overshadowed hia sewerage encineciriogt he did
•omrt of the heat work of his tiii^e in the liitt^r line.

James P, Kirk wood, born \u Seotland in 18C37, wa» on»* of the moat painatakins cnnineer*
connected with Amcrinan sowerago work. He received his technical education am an appren-
lice to a Seotch enirinet'ring firm, and then came to the rnit^ States From l»."}'i to IR55
h« was en^aited ntainly onVailruad work, in which he row lo high ofliee. but was also deea-
vlonaliy employed by the fodernl government. In 1855, ho unHertook some difficult reeon-
atnietioQ of water matn«> in New York, which attracted to much attention that in the follow-
ing year he was made chit^f engineer of the BriMtiktyo water works. Bc^fore this work waa
oompletjed, his health bcnamf poor, and nUhotiith he wii» sul»sequ«intly consulted by nmny
cities and ptannf^d many importttni wftt*ir works he w»»m unable to ainiot-pt the numerous
invitations to build tlie works he designed. His eunneclion with sowcragt.* plans wiis
ustmlly that of a court of final juriwliction on the designs of othera, and the eonaervatisfu
of hit viewt, aa expreaaed in the old reports by him in the Ubrary of the Arnerican Socioiy
of Civil Engineers^ is in eontm^t with thoai» of the eontcnipurary Anierteaii advocates of
9ximut\y small p*t*^K and otHi'f vas^ri«w» due to Chad wick and his followera In England.

Ills most ti
gation of 1 1
He waa tl
Of all I
•ystema, C

j*^ was prnb 1 1
-, made in i

1 .13 .111- Aiii^-rnufJ Stwicty ui i Mtj i.ii^i

were prominent in planning the enrli-
Ml* is probably the t>est knowu today, for i

a with an invest!-
Hoard of Ib-abh

find Dr»inj» for Populous Districta," publiJihad in lW*t). wml* widely used by rngiueers lor ai
leajit 25 yeum, and his prof(<4sionat activitiiwi in many dir<*etian«, such as talking tlie p«iopla
of Brooklyn itii*> starling tiie Brr»*klyTi bridge, made him a w«»lbknown porsonagn. Ilia
rmrly (engineering work was don*' on raitroada, and it was not until lR+\7 that h** uodertHok
liift imwctmao of Uit»oklyn< mc^tiotifHl in aoma detail in this Introduction. Tha book r«ferfwl

TNTRODVCTION

15

ften thoy were constructed by individuals or the inhabitants of small
Iktrictti, at their own expense and with little or no puljlic supena.nion.
In the rarly part of the nineteenth century water boards were not in-
Vequ<«nl!y pljiced in charge of the sewerage works, which were Ui^ually
fiainly for «irainage of stomi water, aa cesspools were generally employed
|for fe<*al matter. The last city to banish them was Baltimore; there
rr SO,(K)0 of them in that city in 1879, according to a report of C. H.
and many of them had overflow pipes dischari^ing into the
iter sewers, which was contrar>^ to law. He CMtiniated that the
anual cont of cleaning? these cesspools, at the contract price of ^3 per
load, wax $9<3,0()0. As a result of the fouling of the soil by the contents
' the^ pitis, the City Health Comniiasioner reported in 1879 that of 71
fjple-i of pump and spring water taken within the city limits, **33

► rrtfy ititt>rv«ltiic w «»*platninR th<» principlPD followed In the BrfK>klyn deaign, which
j trt lw» t<iO «ni«tl iri <ho IfirKor «*ectionjt, n fact he acknowlf*rlir»?fl without lifsitjition a#
t It wnt iivi*'k'>^<« llft^i frruuently mentionpil ns proof of tho need of tws'ltor knowlrdgi*
A-mrnla^l \ i rleiilgn thnn hp posspnaed in 1S57. He waa frequently iftnincd

pa** m* I iitn» and wTot^ from tioic* to rirnf to tho pr^ra nn ihp mihje<»t,

%t\y wii'kW hi* wu!4 it'lviiKiry editor of Bngint^rim Stxt*; Ho will ihe sixth presi-
' till* Amirrirun 8orJf ty of Civil Erifincrre,

Hn^ion int*>rr**piinii •cwortm** wyslr-fr* vn* nuthoritcKl hy ih** k»|ri»1fttil^^ in 187<\» on

%\ve \mM\* of » tri>ort liy E. 8. Chpflhrouuh, Mt]««9 ^Ane and Chas F. Folsoni. Iho IfttU'T the

-■ * '\\0i Mit!«iar<hujifttji Suin Board of Health. It wi»a cleBittn*»d and partly

lilt >\Xv of .1o•^'ph P r>(iWj«, who had gninni rjtpt'ritTrcP nrwler KirkwonH

mI I .: i v^un a «iirci'«»or uf (hn InitiT an rity eniptipor of Boston. Hiit ftrt^ot

i»i' |> nvfTnion to a cyonnpif uou» pcwition tn public lod him to decline on *efv«'r»l

«»• <ii4tioD it« prt^Bidr'ni of tho AniiTtraii fioriety of Civil Eftginecra, The int<?r-

ueing Nrwvr»f(t< Myninm of Boottoti wnn thr fir^l frrrnt undf rt^kiti^ of the kind ia this countrf #

I r»*^ M« df«#lrfi»T nn inr/»rnfttionnl distinction «» ft sowt*rngf »pi*einiUat.

Tf ' (( of rmvifhmfv WU9 dednred in 1881 by Rudolph Herinjt. af t«*r a per*

uf^h irork in our cititM nnd io Enropr. to bf* o^jual io anything abroiid

ttw^ work rUewhtTc in Ihia coantry. Th^ systtem wa« deaiKncd in

'dd, Ihtn rhit'f fnjfinepr of tht? wnt«f works »nd Inter eiiy enjtino^f,

1 uruUr (ki- V' raonal *up*'rvi«ion of his iinsisiantA, Howard A Carson

lirifit^r. Mr. 8hfdd'* report of 1874 on thc*«? »pwer-

I iu£ dorumnrU. Ilti dr«Km'd hia acwer* to cany off

•t/4r-«. ft- p*** iJiuiutti ptff ftrrr, wtthntit rntirrly filhuK their miction, and t'mploy<*d a run-

liari»ilUT>*''T«'id*n^lnrthi»<>fTf»rtof different slopes, with tho nwutt thai hiii cro#A-spntCon«

Iktr ■ I th«nr pufpo«. At th<i requcjit of ihi* mayor, th*? system wai exnniinpd

\ h\ '• 9. Gr<frnc* Col. J. W. Adams and E. S. Chnabroufh* who roporttd

hll w* ' 'Vt-hc dftaila of constniHion . havi? b<«t'n CFirrird out. with

lȤfiliM^I^' -n which In niri*ly accn In such work." Owinjf to tin* hitcr

.. i>fk, it in only Hifht lo point out that iht* Providence aitwon

dm ntoilcl AfiKTij'tii MVMt*>rf>.

^ . born 111 Boston in lHi7 nnd educat4*d at Harvard, waa entAi«d on

1 •iruriural (rninniM«rin(( mainly down to thn Ci\dl War, wh«n he bneami*arttv»»

ill tK« work Off th#i J*anit«n- Commi««ion and th«« had hit attoarion turnod toward pubU«

llll matl«T«. lf«i wa« a im^at Mtudrint of •r>w«»raitr and 9owau<' dtJit>o«al probloma atid wa*

Hy «iiffaic«'d ity r»rnort on thrm, bnt thi" erf«at4*r part ot h'xm profnawional work n?-

1 in ' ' * i - ... * ij^^ crTtM't oft Atotrr . . _ .;

J wriiiuit about the «ul'

\ a I,. . Iw.,/ n-s lfL-.ntnrr. .,r I ..: .,...i

ronipojlwl
r'"l ol good

16

AMEBIC AN SEWERAGE PRACTICE

were filthy, 10 bad, 22 suspicious and 6 good/* In 1906 Messrs. Hering,
Gray and Stearns reported on a general plan for the sewerage and
sewage disposal of this city, which led to the construction of a com-
prehensive separate sewerage system and disposal works.

There was a tendency in this countr)^ a-s elsewhere to construct the
early sewers of needlessly large dimensions. One of the oldest sewers
in Brooklyn wa^i in Fulton Street. Although it drained an area of leas
than 20 acres and was on a grade of 1 in 36 it was 4 ft, high and 5 ft,
wide. For many years the largest sewer in Manhattan was that in
Canal Street, built somewhere between 1805 and 1810; it was 8 X 16 ft,
in section and al>out 1850 was in very bad condition » being referred to by
engineers of that time as affording instructive information of things it

It would not \^ proper to cloae thi» brief list without a rocnlion of th<» unique position I«»M
by Dr. Huiiolph tteritig^ in the hlstoiy of American ncwemjce. Like others nHmcd^ ha took
up sewemne work by chiitic«. H« wa4 ensaged for a number of yeart in flupervisina the
ooiLstruotioo of various munloipal works In Philadejphia and in this capacity ho rebuilt
tome of th« dilapidated fltnicitureA of an earlier day, constructed in many cases with porous
inverts for the purpose of udmtttiug ground WTit<»r and draiuins cellars. This h^i him to
invcstisatci the reasonii for ttitr failure of thr«o old sewers^ which proved such an intcrestinc
subject thai he prtKtentcd the matter as a paper before the 1879 annual convention of the
American Society of Civil Enidneem, It will be found in the Society's " Traoaactions," voL
vii. 252, and was not only the first, but also for many years the sole, Arncrican discu9«ion
of the design of sewer sections to carry the external loads coming on thern. Althouich it
was not so stated In the pap(*r, the sections wer« dtwij^ned to r*st on plat forms and rtfftint the
moat unfavorable loadinss to which such BtmcturcB were exposed. The sections wera
thus somewhat heavier than would be needed under many conditions, but their publication
was beneficial as counteracting a tendency at that time toward very light construction
This ajid other profcssionni papera, on allie*! subJcfU attracted sttcnlion to their author,
and when the National Board of Henhh desired to make an investigation of Kuropeaa
seworago work« ho was naturally srlr^ited^ Wing a graduate of one of the iH'st German
polytttchmc sehuols nnd familiar with Amt-riran *anit-ary engineering practice* Bearing
lettant of introduction from a powerful serni-Hjfficial body, he was able to gain the close ae-
quaintau<^e of the English and Eurot>ean s<fwernge engineers, and to ascertain what the
leaders among them thought of the many disput*>d featurt^ of their work- His report of
his work, forming the first dear American analysis of alt tiiv main problems of aowoniCiO
and the mr«thorls of sf»tving them, ttstabUshcd hit reputation as spi>ciiili9t.

Finally* the name of D. K. MoComb should bo mentioned as the first American cngioeer
who dared to build targe sewers of concrete. Many wished to do tlus^ but were afraid of
the quality of the concrete which would be produced as a city job, just ix« l^i^ t. . i;.... ^f
distrust Innted luany years longer in Groat Britian and led the Local Govcr >i

to retiuirv iu the ease of reinforced cuiiercte sewerage works an ainortisa,liou fun> ' 1-

ifig t>o A life of lA years only. Mr. MoComb was superintendent of nt^wers in W aahinginn
aud was eoovinced he could get goofl rmulu. In ISH.'I Cnpt, Hi, L. Hoiie designed a 15 X
17H ft concrete sew«r with a comploit* briek tilling, which was built in 1885 under Mr, Mc*
Comb's supervision; this sewer was 2500 ft. long and the matimum depth of irtrnch was
about 00 ft. Another concrete 9«*vir>r d*^igned and built at f'
seciton tit 10 ft. diaaicler and a brick lining. Thcs«t ar« the on :
ton with a brick lining in the invert and arch. In ISH8, Mr M
svwer T.tlA ft. iu diameter and ^i ft. long, and in cuoDcotiuD
of eoncrete^ with an arch tif 24,4 ft, and a rt*^ of 4.5 ft., th*

1.5 ft. 8inoe that date the live of cnnrreto in sewer enoAtruptlon lias tumn tiie n»ie in Wtk4
ington, the inverts btting usually tiuMil with vttrifled briek. The sueeesM of the i^sft ctpe
ment lt»d lo the usm of r\vwTnt« for large srweri* iil»cwher«» and it was soon •'
thatthi»y were teeaet pens (v)» thill briak »(?wers and tH?uld be niada without avrio >
In ■•eartiic gwod mifluuaiudiip.

Tntroduction

was wise to avoid. Its large size was doubtless made necessary by the
exbft<!nce of a brook at thL:* place which waa at one time provided with
pLafik walls and was ii^ed t>y small boats, as illustrated in Yalentine^s
** ^ ' ' ')f New York,^' In some cases the sewers were not only very

Uk <'n outlets but were continued of the same sixe to their heads;

it was inipoewiblo to secure adequate velocitj' in such sewera unlass they
Wifv laid on sleep grades^ and consequently some of them became offen-
•ives when the sludge accumulating in them unde^^went decomposition,
In 901 < he grades were in the wrong direction; an instance of this

in meii' M a report on Boston sewerage problems made in 1876 by

E- 8. Chesbrough, Moses Lane and Charles F. Fobom:

•'The fiiling-in of the old mill pond naturally' necessitated the cxtonsion
of tlic iicwcra of that district to discharge into the canal; and, upon dosure
of Ihe canal, the sewers were intercepted by a main which now dischiirges
OB both fiidca of the city, ver^' irregular in grade, and whose two outlets arc
nalrrianir higher than its central point at Haymarket Square^ thereby
ttOiiog obstructions in that whole drainage diBtrict."

Such conditions as the^e produced the same nuisancea w^hich were so
so marked in English and Continental cities in the middle of the last
ornlury. For instance, R. C. I^acot, superintendent of the Jersey
City water and sewerage works^ reported as late as 1805:

**Th^ »itnfttion of these sewers and the necessity of their entire reconstruo-
ti rought to the notice of the proper authorities in my annual

p'i t four yt?ars, but nothing has bet*n done by those immediately

iinffmrt.^ri to remedy the evil. The outlet of the Henderson St. aewer
(which i» tiie receptacle of all these lateral sewers) being effectually closed
Up at ihm Morris Canal, no sewage inatt<'r can pass away, and consequently
thm^ miwtrn are almost entirely filled up with putrefying matter."

*' ^ "rouble was caused by the construction of sewers by private
i and their subseciuent acceptance by the city. As long ago
n s Chesbrough and Parrott protested against such work

hi _.- : ^ terms^ in a report to the City of Boston:

*'A» the law now stands, any proprieUir of land may lay out streets at
fuefa li!Ti*l as ho may deem to be for his immediate intcrc'Ht, witliout niuniripal
ii**-'' "^ " "f'; and when they have been covered witli houses and a Ixu'ge
I' riri» mifTering th« rifplorrible consequences of defective seweragCi

tJ ■' , is calle*! upon to accept them aud assume the resfjon-

»j I remedy/^

About thf« ttmo that the last quotation waa written there was consider-
ahlodiscu ng Fnglisb engineers concerning the proper grades of

'irwer*, iixi . iitrovcrsy wa^i duplicated on a less acrimonious piano

>ii ^1 ' 1 titled States. Lindley and RawUnson were among the leading

18 AMEHICAN SBWEHAGE PRACTICE ^^H

advocatos of flat grades with ample provimon for flushing, while Wick-
steed was prolmbly the leading champion of enough slof>e to keep the
sewers clean without other fluiiliing than way afforded by the ordinary
maximum daily flow. The low-grade school hati its way with a vengencc
at Charleston, S, C, in 1857, where a sewer was built without any slope^
It was 2-5/8 milea long, 3-1/2 ft, wide and 4-1 /2 ft. high, with plank
bottom and brick sides and arch» Each end had a tide gate^ and the
tides were such that a flushing current could be sent through the sewer
at certain times In the da}^, strong enough to move broken brick, sand
and clay.

8ome of the difllicultiea which the American designer of sewers, without
professional treatises of much value and lacking the help of the profes-
sional societies and journalii of today, encountered in the middle of the
last century are set forth in a report by Strickland Kneass, Chief En-
gineer of the Department of Sewerage of Philadelphia, in 1857:

**That portion of our charge which reqiiirea the most mature deliberation
and careful examination is the arrangement of syst(*m8 for drainage, with
the proper proportioning of the sewers and drains constituting such syst^ms^
and hiLs required a course of study and research that has been but little
attended to in our city. It is a subject that has auch a variety of elements
within it as to have rendered it a matter of close investigation fur a series
of years in the city of London, by Comissioncrs appointed under acts of
Parliament, the results of which are very voluminous and furnish much
practical information, from which maybe deduced laws of great value on the
qtieation of waterflow in sewers; yet so widely do they differ from experiments
on record, made upon a (small scale — upon which our mathematical for-
mulas have been estabhshed — that judgment must be exercised in their
adopt ion ^ fiut we hope to make «uch experiments upon some of the most
perfect of our own sewers an will enable us to draw a comparison between
their practical and theoretical value. Xevertheless, we have given the
subject much consideration, and believe that the principles upon which we
have arrived at the proportions of those sewers and drains already designed
are correct, and ivill be found to be fully adequate to the purposes intended,
yet with a strong hope that much saving maybe made hereafter by a further
redaction in the porporttons of sewers for a given drainage/'

The foul condition of the streets of Philadelphia at that time, owing to
the filth discharged or cast into the gutters, is evident from another
(juotation from the same report:

''There should be a culvert on every street, and every houae ahould be
obliged to deliver into it, by underground channels, all ordure or refuse that
18 8U8Ci*ptibk» of being diluted. The great advantage in the intrtjduction of
lateral cidverts is not only that underground drainage from adjacent houses
should be generally adopted, but that by the construction of frequent inlets,
our gutters would ccjise to be reservoirs of filth and garbage^ breeding diaease
and contagion in our vety midiit/'

^m

mTRODUCTTON

About the time Kneass was hoping that experiineiita would enablo
Hm tu adopt smaller sewer sections, another American city was under-
tinj£ the construction of a sewerage system, baaed on the best English
' >d^ which taught a needed lesson of the danger of con*
m any other basis than a complete understanding of the
lUirementd of the locality they w<^Te to serv^o. The lack of such in-
flation was pointed out by the engineer of the works in quci^tion,
Ihc Brimklyn undertaking of 1857-9» which was designed by CoL Julius
W^ ■ Ho later became the sixth president of the American Society

f C 1 - :_ ^ mecrs. In hla reports of that date he made the^ statements*

use 1
Ktby

'^Thfi eewerB in tliia city already built are too few in number^ and their

too resatrictixl and with too limited a supply of water, to enable us to

ive froni them data of any value whatever, and t\w attempt to obtain

by gmging the sewers »« New York City, with ttie imperfect system which

^from past necessity has prevailed there^ would lie attended with a great

ixpefiiliinre of time, and from various causes, great un certain t it ies would

f «a to the vnlue of the results obtained. No gaginga, to our knowledge,

IhjiV€ ever been made of sewers in this country, and very imperfect records
ftxist of thedr dimensions, inclinations and other chtu-ucteristica* If gagings
Imvis been taken, they have been too limited in scale to furnish data for a
lYftem of sewers in a city of so rapid a progression in populat ion as Brooklyn
promtMeM to be; hen ex* we are driven for the neceflaary infonnation to those
cities abroad where the subject has been forced on the public attention for
.ftftrles of years.
' **FTain rocortled observations it appears that in a particular district, a
fiialall u(f 1/ 2 m, in 3 hours took 12 hours before the flow in the sewer resumed
iii orrtinary level on areas such as we are considering, and a rainfall of 1.1
in* m an hour and 0»3 in. in the next 2 hours occupied in discharging 15-3/4
boim; tl)O0e points nearest the outfall draining off first, the most remote next,
Mid spme jioTtions would be entirely cleiu" before the water from the most
ttmoUf points would reach tfie outfalL

**The pfpwnt phin is calculated for a rainfall of 1 in. in an Ijoiir, to be
diicfejirirr Mirs, or a discharge of 1/2 cu, ft, (3-1/4 gab) per second per

ISffl£ of (i: d.

*'Ii hfflii bfH'n m^n that we may estimate one-half of the flow of sewage,
iadtidtiiit all waste water due to 24 horns (evcr>^thing but the rain J to run off
in 8 hoam, from 9 a. m., and that the sewage equals in amount I'-lAl the
« '*— -'■•'•"'», or for 40,tKX>,<XK) gal. water the sewage may be estimated at
\., the half of which running off in 8 hours, gives 3, 125,000 gal. of
w^igi i**r nriur during 8 hours, which, from 12,tXK3 acres, gives 260 gal. or
51 oi. ft, |>er acre j>cr hour, or less than 0.01 in. in depth over the whole area,
ttkilfr lb* oupaeity of the isewer is calculated for an inch in depth."

To avoid intricacy of calculation and to err on tlie safe side by an
thiJ dimensions of the pipes over the ttl>solute requirements of
according to Colonel Adams' report, it was permissible to

20

AMERICAN SEWERAGE PRACTICE

employ for limited area«, at the summits of branch sewers* aiid elaewheii
as experiment might dictate, the ^* formula for di.schargo from a stij
reservoir/' but for larger areas and mains he preferred to be governed
by Roe^s ^agings of the London sewers. The minimum InahnatioU
given to the sewers, when running half full, is stated in Table 2, and wa
considered great enough to produce a velocity ** which will sweep away I
any substance which should be found in the sewers and many which^
should not. This quantity of water can be introduced at any time by i
the process of temporary dams or gates at the manholes, prod\icing a
sudden flush or scour of the sewer by water from the hydrants." Thiti
table is of intercut in comparison with the authors' recommendation3_
for minimum grades in Chapter III,

Table i, — MimwoM Grades REcoitMENnEo in 1850 bt Col. J.
Adams for Sewers Flowing Half Fl'll

Diameter, in

8Ioi>e, ratio

Slope, percentage _

6

irV
1.67

0
Ml

12
0.5

15
0.4

18
0.33

24

Tb
0.25.

It might be added here that the recommendations for minimum slope
for brick sewers 30, 42 and 48 in. in diameter were i in COO, 700 and 80
respectively. By way of contrast reference may l>e made to the mini-
mum grades adopted by C. Howard Ellers, Chief Eng. of Sewers of
Chicago in 1881, which were 0.2 per cent., for 12- to IS-in. pipe and 0.i|
per cent, for 20- to 30-in. sewers.

Although Colonel Adams waa a leading student of sewerage pro bleu
and his plans were cliocked by James P. Kirk wood, a most careful and
thorough engineer, the system proved inadequate, as is shown by tl«
following quotation from a report of the chief engineer of the Brooklj
sewerage works on Dec. 23, 1870:

"Your engineer has been aware for several ycmrs of the iiiipf»rtanee
improving the sewerage system; and the frequent complainU of houa
holders in certiiin loeahtiea of the city have cnuscd the moat careful h
vestigations to be made from time U> time." Many of the main sewer
'* proved to be too small since the districts have been built ov<»r, and
in not a few instances, at too low a grade. The lower portinns of man
diHtricts are frequently inundated » and what is proposed is a system
interception of the sewage and sionn water of the upp**r portion of sue
districts; the lower sewers will then bo ample tn m»c to deal with the volu
of tUiw which will !>o due to them/*

The hihtory ol st'ss <
rtHHjnt timeei by junt ?<h

^pu markinl until
ice on imjierfect i

INTRODUCTION

21

dosi^.i Much damage has been done by flooding ccUara with stomi
water and sewage from surcharged sewers. Under the law of most
irtateA, wliich is explained in great detail in the famous New York ca>ie
reported in 4 N» E. Hop. 321, if the city and the engineer follow out the
legJil nxiuirements governing sewerage works, parties damaged by reason
[of defects duo to mistakes in the design have no ground for action
JikKt the city. This shows tlic grave responBibility of the engineer
makG8 it incimibont upon liim to utilize every possible resource
f wlienc« infonnation pertinent to the design may be secured. The Icgrd
I rule in question was stated briefly as follows by the Maine Supreme
I Court in Keely v». City of Portland, 61 At Rep. 180:

A tnunicipal corporation ia not responsible in damages for injuries tsaused

) ti* a pcTson'ft property by the flowing back of water and sewage from a public

[newer with which the property is oonneoted, where this injur>^ results from

I the hxnition or plan of tM^nsirviction or in the general design of

tn, ftn«i not at all because of want of repair or failure of the

litti ! t<» tttainUiin the sower to the standard of efhciency of its ortgitial

|ib-i t ruction,

A peculiar aspect of the subject was settled in 1905 by the Nebraska

I Supreme Court. In 1882 the city of Omaha adopted plans prepared

I by Cohmcl Waring for the sewerage of a part of the city, although the

I city etiidneer, Andrew Rosewnter, protested against this action on the

gft" ' the propose<:l lateral sewers were too small, being but 6 in.

ia 'i The system was installed and it became necessary to build

I a larger sewer paralleling one of the laterab*, except where it was on a

A property owner brought suit to enjoin tlie collection of

rments for the larger sewer, contending that had tlje city

^^ Uii; ail vice of its city engineer, it would have saved the money

wmImI oq an inadc^^uate system. Tlie court ruled, however, that wheo

I "tbe Cfiiy council, misU*d by the glamour of a great name, employed

' Colnnet Waring^ they did what any prudent, cautioiLs businessman would

hftve done luider like circuuistanccH and the plaintiff cannot complain if

I tli^tr judffnient was erroneous.'*

t Amuai iW «r rag* tyiti^ms built in onrly dnyn in the? Fnitwl Slutc* thai in th.^

briMbrt frf B» hiw nn excpptionnlly jirominent place, for tho mothtxlH of «!< ^iifn

...kt^A by A compli't** cliareicnrd of proper oi»ginp«rin« priacipl's, ui*

allowing ciuotdttofi from ■ pnpcr by C, H. Gnuiflky oo *'Th4» 8«wer

i^t'fj" ill Tr»n«i. Am. Soo. C, E,. Uv, 20ir

: «n . , . m*i»mN to hiive been to oonmiruot rfii-eihApcd briok wwi»ni, 5 ft. hiRh

«ktr». iu All ttrcfta uniJ nlkyii whvrr property wab valuablt* Aiiil couM Affortl lo pay

l%# 'A'cr Ar»vr«. » . , ThuaiAi! of (M.>«rer wa* frcqunatly tIeti?rrmmKl by the SupisrinU-ndi'iil

^ ^invte, who m%m tinv^nr a civil nnKin«*«*ri . . . The* invftt, a« n^quircd by orditinnn^*

•ii pl^c*^^ '" "* ^ ' ' * -fifie, itrrK^rnlly li*vcU of, du»' to tlK* int4'lliM''n»H* of looft of

- lower lit th« down^hill ■id*' of tht- ptr«'€''t intrr^t'^'tion^ 'i'lir

Mnni<rt. v^itb oififr brirk itcwrm of lik«i mixn, ur with lArir«^r

>110« lo wtuii mmm j>rcgcrib«cl «t tonw oiliitr linid, for

22

AMERICAN SEWERAGE PRACTICE

The sufficiency for ita purpose of one of the largest sewera m the
country was approved by the Missouri Supreme Court in the ca^^e of
Gulath vs. City of St. Louia, 77 S.W. Rep. 744. This related to the
Mill Creek sewer in that cityi draining about 6,400 acres and begun in
1864. At its upper end it h 10 ft, in diameter and at its lower end, 5
miles distant, it is 16 ft X 20 ft. in section. It was designed to care for a
rainfall of 1 in, per hour. Before it was built the site of the plaintiff's
store was overflowed by the creek many times, according to testimony.
After the wewer was constructed, the site was overflowtHl but three tiraei?
down to the date of the suit, and on each occasion after an unusual
storm. The court ruled that such exceptional atonms need not be taken
into account by the engineer in designing such works.'

Although where a properly authorized official or committee adopt^!)
plans for a sewerage sy.stem it cannot be held responsible in most states
for damages resjulting from defects of design, it has been held by 80me
courts, as the Wi>^con»in Supreme Court- in Hart vs. City of NeiUsville,
104 N.W- Rep* 699, that the mere existence of sewers will not be con-
sidered the equivalent of a plan* In that ca.se the court held that if a
sewerage system was constructed without a properly adopted plan, the
city is liable for any damages that may result from defects in it. The
court also ruled that though a city was not liable for damages to private
property caused by mere defects in a properly adopted and executed
plan, if it wan informed of such defects and the direct continuing injury
to private property that would result uidess they were remedied, it
should exercise ordinary care to prevent such a result and was responsible
for damagea caused by any negligence in this respect. This ruling
indicates that when a city takes over the improvements made upon a
large tract of land, such as the ** additions*' so frequently absorbed where
communities are developing rapidly, the plan and construction of the
sewerage sj'-stems should be very carefully scrutinized before the papers
are finally signed.

In the design of sewerage systems down to a comparatively recent
date there seemed to be a strong preference for outfalb in tidal waters

■ Tlvb wiu ezpraMM»di in the foHowinft words lo n preUmitwry n»port by thtt Neir York
Metrop<}Ut»ti SoweTAito ComtiiiMioti: "The iinpart&acfs of c^vItia r<ftrofu| cwiDAirliirmtioti ta
ttio' rrunfiilt ii grcntC'r Itt degigbinit eoU(»cttng tystema of iewerAxe t.hi»u m providing for fiii»l
dlist>OAtLJ«>ii. The CunriJon of &uch sewera is not only to cftiry off ibe df Ainago ot ibe bouwm,
but to prevent »coumutj(tionA nf w<itrf in the alreeU, It tom^rtlnMn hAppena, wben €i<re«wtv«
f*n« of mJa occur* thnt i»rwrn» ure Burchargcd, At «uch Uinc* UlQ dfitifi&gjc ol houiet U
ittb-rf'*^*'^ «i(i. .,T^H fatten »toi»p«Hl, in whicb - '^" -"ii,.r« „...,- k« tfrw^i...^ ..«.i ,.H,..r ...*^,..t*
inrr. ,^,L It 1* uaiiiktly impr

«u<f I i.» oArry mwi^y tint wjtl< f

Uvflw to tnaurt} timt incon vt^nicnoo from fionding nhiill nnvrr ocrur. At long mtcnmla nun-
fiillfl r>f i«s(M*ptlonfii severity l*k« plao«i mid to provide for thete JKrwcnt woutd hnte to bn
built »o very largn Utut Uiisy would rvoprutsnt « euniitU«)n»bl« invttstmont ovrf tb* ium
r^i|ui^»d to tpm them wiiifiricat oapiuiity im ftU iUif ordioary ftod ino«t of tbo bo»vy miiig
whirh iirii likely Ut f»U;"

iNTRODUCTIOt

t

which were locked by floo<l tide, and it was by no means rare to find the
outletH at an elevation which insured their submergence at mean tide.
In its investigations of the sewerage systems discharging into New York
Bay the Metropolitan Sewerage Commiasion reached the conclusion
tbut tw^o opinions led to this construction, the first that the sewer
om should be given as much wlope a.s possible in the belief that it
iiroUed the velocrtj^ of flow in the aewcrs and the other that the wind
blmving into the open ends of the sewers drove the foul air up into the
«treet^ through the perforations in the manhole covers.'

Another cause of flooding exiisted in some sewerage systems otherwise
fnee from defects. This was the preparation of sewer plans by using
the iDvert grade or bottom slope, for calculating capacities, instead of
the hydrauUo grades* or slopes of the water surface in the sewers. The
^ mistaken policy in Brooklyn down to 1007 , was ** to produce
I would overflow at manholes and be^ ao to speak, drowned
out whenever the flow approximated the maximum capacity. '* (Report
M<yt.ropolitan Sewerage Commission, 1910).

Thtj United States suffered, just as England did at an earlier date,
frasn the improper design of separate systems of sewerage in which the
homa sewage and rain water are kept nearly or quite distinct. Just who
doagncd the first ^stem of sewers for removing house sewage separately
It not definitely known, but the principle was strongly advocated as early
At IH42 by Ed\inn Chadwick. He ha^ been called the ** father of sanitar
tioo in England," and unquostionably played an important r61e in
armuing that country to the need of greater cleanliness not only in
dtioB but also in rural districts. He was a m^n of con\dncing address,
|r^ " Stance and enthusiasm, and strong imagination which was

iiij ly not restrained by technical knowledge. As a result he

idircieal«<i, e%'en in meetings of engineers, so-called hydraulic principles
tad dome features of design that were wholly incorrect and at last re-
iulled in bin being publicly branded as a charlatan at a meeting of the

i

In of Civil Engineers

Pf C. E.. xxiv).

>T1k«i ihlm .

at which he was in attendance (see

rr , H,u4 j>r ki iM«- had beeo »t>ftndoii«d by leadioc engino^ra beforo tb« biTth
•♦ of iUfHC p«gc«« atUrnlioci in called to %h6 fultowins fftatemcnt io a rrport
Brudklin*, Nf»«i»., iniwJc tn \H7Ti by E. 8. Cbeobrough, W. H. Br»dlcy
rhilbnrk: "'With roftArd to tbe h<*i£ht of tb«» outfntL twc imp^ortant reuon*
n it n* bUb mm fioiqiibli}: vii,, lo pre v out tbu influx ot tide wntcr at the mouth«
: tiot) witb HJi> intvrreptitiit aewcr wbicb tumy bcrenlt^r
v^ Cliftr(*>« Uivor for BrMntor* muI vidnity. On tbeotbor
':'- Mjilft iiM low UB poHsibU*. both lo necure mn effioietit
1 •. rll an may be tb<? low-lyimt dinlrict. . , . W«
•( rbe outfnil h^ tilttO«-d nt Ibt* k'wt of balMidc, »nd
!" ghw be pUti^^d ibnn>. Should a Brntid r«ohem4i ever he carried out tor
I lit Mwtrni fur Barton, it b prnbublo tbnt rnaort must bo bnd to puuiping

•u^Jii it. iicbnmn Mucrcimful, in wbirh c<iho the tow lovel Abovo named for (be ouUit
4f Ite llHPoklliie Mwir niU ii«?t bv fouitd obiccUouiiblo.**

Hi

2A

AMERICAN SEWERAGE PRACTICE

The principle of the separation of house sewage from rain water, ad vo*
cated by Chadwiek,* was so meritorioiLs for many placei^ that it waa |
developed along rational linens by a number of leading English engineers^
notably Sir Ro!)ert RawhnsQn, whose *' Suggestions as to Plans for Main
Bawerage, Drainage and Water Supply/- published by the Local
Gov^ernment Boards did much to pre%^ent the laying of sewers of too small
size and poor alignment, without proper facilities for the cleaning which
is likdy to be necessary in all such works.

The separate system received much study by American engineers,
as was natural in view of their reHance on Englisli practice for precedent.
Fortunately, however, the difference between the character of the rainfall
in England and the United States was known here and its influence on
the design of sewerage works was appreciated. The English rains are
more frequent but less intense, and hence our storm-water drains mast
be larger for like tupographical conditions* Our heavier rains afford
more vigorous flui^hing action in the sewers, so that the necessity for the
rather elaborate provisions for flushing combined sewers in many Euro-
pean cities is not so evident here. Wherever the surface drainage could
be oared for satisfactorily at a low cost without the use of large combined
sewers receiving both house sewage and rain-water, there was a manifest
advantage in adopting the separate system, which was used at about the
same time in designs prepared by Beneijette Williams for Pullman, 111.,
and George E, Waring^ Jr,^ for Memphis. The Memphis aj^stem was
the most conspicuous, although a comparative failure, a fact which the
|>eople of the city naturally suppressed for business reasons for many
years. Colonel Waring received two patents, Nas. 236740 and 278839,
issued in 18S1 and 1883, for separate sewerage systems, and his use of
these patents in ways which many engineers regarded as unprofeaaional
brought severe criticism upon him.

During the summer of 1S73 more than 20O0 persons die<l of yellow
fever in Memphis. In 1878, 5150 deaths occurred from the same
cause; a rigid quarantine and sanitary regulations were enforced but
the disease was merely checked and during the next year was the causa ,
of 485 deaths. The Legislature authorijficd unusujil taxing and adminid-
trfttive methods in the stricken city, who^e affliction aroused the sym-
pathy of the svhole nation and was largely responsible for tlu^ formation
of the National Board of Health, A committee of the Board sent Colo

« John PhltlipB, in a ps^pcr ruini iHjforfl the PhJItMophi^^at Society nl GlAHicovr, Fch. 7. 1872,
Mid; **Thp pn^^pipl^ of (irnlnAK*-^ it> townt whi- >^ ♦ >.,{, ,.^,,t.> .,.,^ «k.r.h « *- r,r-* r.^r^^^^n^i
Vy tn«, U ealkU tlu* S^'ptiraus System. (It u it tuntir

of tJiift 8y«tr»m» but tbui ia not ili«i faci.) 1 h: , ^ yrm^n

before h«s rr^iii»rit*U»d tt in IMS, Thi» ir»i m 1**7* wlwn i wim C'hirt Survpyor of « larieo
t>orUon of Uic* Metro:po!ita.ii llM^ndon) •rw«f»« . * . la my pn-Uminury report its JMf)
on ihf4 dralttftgi? of the M«iropo1tfi (lytindon^ f pn7p«MM«J ihttt «y9t4tm tut mlofximn. Hut
|MjhlM npininn w«* not thr>ii iintpnrrtl for thli lulvnnv^M MniL, nnd, tn roaM*t|i|*'n»!>,, my
pfQimtml uol ooly fuet with uv »upporn but vitli cotiildeJttbLo oppg«itioii/'

JNTBODUCTWH

"Waring to the city, which was inspected and sun^cyed under Iiis
^itdnn. The maximiuri sam that couUi be raised by taxation for
was S36S,702, and sewerage was greatly needed so it was neces-
V go as far aa possible.
I ;^ricd a separate system using 6-in. lateral sewers
la 1 12-gaL flush-tank at the he^kd of each, discharging once in 24 hourn,
hficisQ drains were 4 in, in diameter. Not more than 300 houses
to be connected with a 6-in. sower; if there were a larger number
Id be provichxl for the pipe was to be enlarged to S-in. toward its lower
The main sewers were made of 10-, 12-, 15- and 20-m. pipe; all
[ tliem were underdrained. All rain-water was supposed to be excluded
tho eewcrs were ventilated through the soil pipes in the houses.
w<sre 00 manholes at first and the lampholes for inspecting the
raf the sewers were a failure from the outset, because the vertical
\ heavy enough to crush the small pipe from which it rose. In
24,2 miles of sewers were built under Colonel Wariog's direction
milm of old sewers were bought, the 20.3 miles costing $183,086.
the next 2 years 12.3 miles were built and bought, and in that
) there were 75 obstructions of the 4- and 6-in. sewers, costing $ 1 1 12
The main lines in some places were reported by the City
Nilca Meriwether, to be taxed to their full capacity. In
2.3 miles were added to the system and 164 obstructions were
at a cost of $ 10S2. During 1885-86, 2.58 mile^i of sewers were
imiii/uctiMl and $2172 spent for removing oljstructions. The inade-
4|ttite cafintctly of tlie larger sewers had resulted in the construction of a
friiif sewer during this period. By that time engineers familiar wnth the
eomditkioji were convinced that some of Colonel Waring*s favorite details
pmvod defective, and that the Rawhuson type of separate system,
<h larger pipes laid without vertical or horizontal bend between
I manholes, was preferable. The partial failure of the so-called
i?ni was demonstrated, therefore, in about 5 years' experience
this was a little longer than was required to demonstrate
thing at Croydon, England, 30 years before the ^lemphis
ttt. The Croydon system was made up of 6350 ft. of 4-in.
' ft. of O-in,, ^35 ft. of H-in., 14,100 ft. of 9-in,, 2469 ft. of
of ll-in., 12,117 ft. of 12.in., 9518 ft of 15-in., 1506 ft.
nd 30 ft. of 21-in, In a period of 20 months in 1852-53, tliere
oppageit in the 4-in. sewers and 34 in the 6-in., but not more
in any of the other sizes.

%Bf' 'Tsonal magnetism in Colonel Waring that he was

r lb* ^r of liis sanitary achievements at Memphis to

ilpnsB his views regarding small pipe sewers on a nimiber of commu-
Tho NAlicinal Hoard of Health felt some distru.st regarding sui*h
•r^tui* *oon after its formation, and it accordingly sent Rudolph

26

AMERICAN SEWERAGE PRACTICE

Heriag to Europe on a tour of investigation, which lasted nearly a year,
On his return he prepared the elaborate report on the principl
sewerage and their exemplification in the best works of Europe alread]^
referred to, which reniain^Hto this day a thorough summing up of good
practice. It is not often that an engineering monograph retaini^
value for more than a quarter of a century. As a result of his investigai
tion Dr, Hering outlined the respeotive fields of the separate and oom«
bined systems as follows:

"The advantages of the combined system over a separate one depeiK
mainly on the foUowing tX)iicjitioris: Where rmn- water must be carrt«^dol
underground from extermve dii5trict«t imd when new sewors muatbelmili
for the purpose, it will generjilly he oheaper. It« cost will also be favorahlt
in densely-inhabited district.^ from the oircumi?tannes that the proportioi
of sewage to rain-water will be greater, and therefore increase the sixes oi
the separate sewer pipes^ yet without decreasing those of the rain-wai
sewers; while the sizes of the combined would not vary with the population
because the quantity of sewage is less than the quantity within which tl:
amount of storm-water can bo esttmated. But more important is the fa<
that in closely built-up sections^ the surface washings from light ratr
would carry an amount of decomposable matter into the rain-water sewer
which, when it lodges as the flow ee^ases, will aiuse a much greater storage o!
filth than in well-designed coin bined sewers which have a continuous flo
and gHnernlly^ also, applian(ses for Aunhing.

*'The separate avHtem la suitable-

•* Where rain-water docs not require extensive underground removal
can be concentrated in a few channels slightly below the surface, or wh'
it can safely be made to flow off entirely on the surface. Such c^mditio
are found in rural districts where the population is scattered, on small
at least short drainage areas^ and on steep slopes or side hills.

** Where an existing system of old sewers, which cannot he made avaQabl
for tlie proper conveyance of sewage* can yet be used for 8t(»rni -water remove

" Where purification is exxjen^ive, and where the river <»r creek is so smaJ
that even dilut^l sewtige from storm-water overflows would lie objectionahl
especially when the water is to be used for domestic purposes at no grea
distance below the town,

** When pumping of the sewage is found too expensive to atlmit of the
oreased quantity from intercepting sewers during rains, which can oooil
In very low and flat districts*

'' Where it is necessary to build a system of sewers for house drain^
with the least cost and delay, and the underground rain-water remove
if at all necessarj', can be postponed.

•*Tlie principle of separation, although often o.stenaibly pnnferrefi
sanitAr\^ grounds, does not necessarily give the system in this regjiectan,
decided advantage over the combined, except under certain definite coad
tions. Un*|er all others, preference will depend on the cost of both 001
structioa and maintenance, which only a careful estimate, based on th
looal requirement^^ can determine/*

^m ^^B^ INTRODUCTION 27 ^H

Tho cast of sc'werage works Ls a subject presenting many pitfalls to ^^|
thoftc without experience^ and even to those having it. The fluctuations ^^H
tie of wiiges and the price of materials from year to year, the ^^H
r of the workmanship required and of the supervision by in- ^^|
ypiK^torH. the oom|ietence of the superintendents of construction and the ^^|
introduction of laborrsaving machinery, these and other factors which ^^H
alfesert the coHt of public works are not readily explained quantita- ^^H
tively» m} thai a public official or young engineer can grasp their com- ^^|
bt£ied effect. This effect m marked, however, b& is well »hown in Fig. 1, ^^|
froKi the 1910 report of E. S. Rankin, engmeer of aewers of Newark, ^H
N, J. This diagram show^ the fluctuation in the contract price of r2-in. ^H
\n\te jMJwers in 8 to U)-ft, trenchos, during a period of 25 years. The ^^|
ctitttA plotted in the diagram were those of contracts for work of practi* ^^|
ciiUy the ^•v&me character and show a range from o 1 cents to $ L 15. Kcc- ^^|
ards of thi^} character can be duplicated in most cities where costs have ^^H

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rcpnring es^ti mates.

isal of the sewage of mo«t cities, until recent yeara,
n the easiest way to becom^rid of it, without much re
\i conditions produced at the place of disposal Irrigi

was apparently practised at ancient Athens, but the
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yeari* ago, when sewage farming was successfully introd

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28 AMERICAN SEWERAGE PRACTICE

pollution by the sewage discharged into them soon became a nuisance.
Interference with agricultural and manufacturing uses of water was
apparently at first given more attention than any danger to health.
Wlien the cholera epidemic of 1854 had been suppressed, Parliament
iws^eil the comprehensive nuisances removal act of 1855, to which
rt^fereniH) has alread>* been made. This did not make sewage treatment
oompulsor>\ however, nor did the rivws pollution prevention act of
1870), although as early as 18G5 a royal conmiission had reported:

"First, t^at whenever rivers are polluted by a discharge of town sewage
into them, the towns may ^easonabl^' be required to desist from causing
tlmt public nuisance.

**Seixind. that where town populations are injured or endangered in health
by a retentiim of oe«»|)ool matter aniiuig them, these towns may reasonably
b<> nHiuinxi to proviilo a system of sewers for its removal."

T^'o methoils of treating sewage came into vogue about the time of
this rejH^rt, The irrigation of land by sewage was the older of these
b\it the prei'ipitation of the solids and some of the dissolved matter by
chemical treatment and subsequent sedimentation attracted more
attention owing to its exploitation by promoters as well as to the favor-
able 0(union of it held by many carvful and conservative engineers;. A
s(Hvial cimunitttv ap^xunted by the Local Government Board in 1$75
reiH>rte\i on the whi^e subject as follows:

**That mvv«c rivers and streams are polluted by a discharge into them
v>f vTude sewage, which practice is highly objecttonable.

*'That. as far a* wv have been able to ascertain, none of the existing modes
\>f treatment v>f town sewage by dep^>sition and by t^temicals in tanks appears
to effev-t tuuch change beyond the separativ^ci of the soUds and the cLuifioa-
tk»a of the liquid. Tha: the treatruent of the sewage in this manner, how-
ever, eiiect* a >x>tLsiv!erabte ituprovement. and. when carried to its greatest
pertev^iv»a. siay ir. s*.^rde cajjes be acivpreil.

**l"tu45 town ^j^waice can besi and sivvc cheapij-bedispc«ed of and purified
b> ?he prvxv^i .*t Un-A irrt;ci::oc :Vy A^cultiiral ptirtKvses?* wh^fr* local con-
vi::i».»t'^ AT^ 'avvraMe to :ts ii'i^^'.-arioc. Vu: :rLa5 the chemical value oc the
sewage is $rca:I> rev;u>xi to the :Ami-;r by the fic^ th^t it =i-i*t re ii^poded
of* .tA> by iay tKri>c^b..*ct :>e ^"iire y*?:ir. atl'.; that its v',»L'i::ie ij generally
^Tvatesc »b.e«t :" "js -*f tbo leiv^t •«er^".-.*e 'o thnr 1a:iv:-

*• I'Sdfct jAii^ jrrticitii.^ii is =Lot vricti-.-abie ::=. jlI .-ase??: jji-i. theret.ice. odwr
stvvies oc ioil:.":^ T^'.th ^ew:i,c? r:'.'-;i^t be ill'.-v^.

" I'h.jt to-*2;#v sif-jAteu :a ti^e :!ea-.v«isit *r *c 'i^iiil ^f^jiruirres. zaay be
al^'wec to turn ?ewa<<:e uirro tie ^ea :c trs'rujL— ■ . "t^i'.-* t.V '. n-e :f* j. «^-vawr.
?r.»\ •litfvi -TO "riijsa^je s* .-a ^:*e«i ini 'hjkt su-.-ti t.'- »*j.' .:" xv-::-":^ rjc ,£ xvace
atu^ be ALo^tfii Aisvi :uaCJie»j. .;i ::!•.• ?o.r- .•: ivvii-.i:.:-

Thse .'jen^iiy o£ yvciil^iricc: Ji Ynzi:!:!".: iir.i tiiif f r-- <ci^ izii^imc oc
ufcttd weii *ui5i>i for «wa^ :artii:.ijc ^-^i is:r%z:*:ii j-d re v.vrTn.-.i.jkr .acer-

INTRODUCTION

20

tivfely smtiQ ar«ft the Bewage was rendered suitable for a fmal treatment
on landt which wm prmiUmViy compulsorj^ for most English ^systems
diiichsLrgmg into fresh water, Thit* coiistrahit was exercised by the
Local government Ikiardp without whose approval money could not bo
taiaed for public worka oxcejjt by sjHi'cial act of Parliament; the Board
imft wodiied to a iinal land treatment until comparatively recently.
Conflbec|Uently aeptic tanks, triekling filters and contact beds were
repeivwl with acclamation and tested on a practical acale that waa
unwarranted, for iujstancc, in Germany.

The dinpor^il of sewage in the United States did not receive so much
«»t'*ntjon 30 ycare ago as in England, nor does it yet, because the
t of the nuiaance caused by its diischarge mto water was not so
marked and l»e<'ati$e of the greater area of land suitable for broad irriga-
tion or in terniittent tiltration on beds graded in situ and of relatively
d^t:^p materials 8uitai)le for the construction of artificial disposal beds.
Its importance was foreseen by the Massachusetts State Board of
Ifndth i-arly in the seventies, and its secretary, Dr. C. F, Fol8om,made
V of disposal in Europe, which resulted in 1876 in a report
mcj^t complete statement that had been made of the st.ate
of the art at that time. Irrigation and filtration were introduced in a
' " T»la<^e«, but it waa not until certain rivers in Massachusetts became
(iffpH'ttvc that any work on a large scale was undertaken. The
treatment plant utilized ohomieal precipitation and was
, ' ?ter, Mass*, in IHS1}'90, from the plans of Charles A. Allen
with the advice of James Mansergh of London and Prof. Leonard P.
M f»f Worcester. It was inf4?nde«i to abate the nuisance cauj^ed
charge of crude sewage into the Blackstonc River, which it
fied^ and it has fvu*nished a large amount of practical informa-
^ding various methods of sewage treatment, for elaborate
tal work, some of it on a ver>^ large scale* has been encouraged
in the behef that the small exjKinse of suohre-
i »aid by the use that could bo made by the muni*
ap&iity oi tiie rt*sulte in planning extensioni| of the original installation
tnd improving the methods of treatment. About the same time, the
Mii.«o««jhtisetts State Board of Healtli, which had been given large powers
? tlui disprjsiU of sewage^ cstiibU^' ' hnviTence Experi-
lor the study of both water an :'• treatment; the

M* n»eare)i work done there has been deep and far-reaching,
r!v noteworthy for the prominence given in early years to
tion, a method of disposal neglected in England on
M^tMiui ni Uiu Uaiited tmvM of land suitable for practising it.^

! '>, tbw mrih"iJ "f tUipueiU hml hmm nmp\nyvd tot » oum1>cr o(

- i' 1.^ I I . s Mil tn DnJilt'v-bnntAifi^e ^'' Tfio VuKHiof luienrutttuit Downwafd
" mUUit «M (»ati]i«UrKj in I SSL

30

AMERICAN SEWERAGE PRACTICE

While thesci introductory notes are intended merely to show how the
principles of sewerage and sewage disposal became established on a firm
footing in engineering practice and not to rev iew the dtnolopment of tlie
detuiLa of the subject, purticularly of Jate, it should be stated here that
recent progress has been wonderfully rapid. When the reason for this is
sought, it will be found in that admirable spirit of good- will and co-opera-
tion existing among American engineers, which not only finds expres-
sion in the w^ork of the enginei'ring aocleties but also in the close and
friendly contact maintaine<i by engineers in this country with one an-
other and with the engineers of other countries. This has bot^n a good
influence on American sanitary engineering, for it has led to friendly
personal relations, open minds and a recognition of the work of others
by giving credit w^hore credit is due, which have combined to concentrate
attention on those tiubjects where progress was most noodotl and to
prevent the needless duplication of effort in striving for the same goal
So long as this spirit persists. American sewerage engineering will go
forw^ard buoyantly.

Disposal by dilution has retained greater favor in the United State*
than in England because of the larger bodies of water available fcir rt^
ceiving the sewEige. The first comprehensive American study of the
subject was begim in 1887 by Dr. Hering for Chicago, and resulted in
his recommendation of a drainage canal to dilute the sewage with water
from Lake Michigan and debver it into the Desplaines River, Bowing
into the Illinois, a tributary of the Mississippi. 8ince then many other
studies have demonstrated that, so far as the prevention of nuisance la
concerned, disposal by dilution Is the most eoonomical method of
becoming rid of sewage at many cities.

Dilution is now (1914) under fire, however, from some health officer*^
and their engineers^ who ojipose the discharge of merely screened and
settled sewage intoriv^ers or lakes furnishing water for potable purpose!*.
While there Is substantial agreement that it is less expensive to obtain
good water b}^ filtering a sewage-contaminated supply than to treat Ul6
sewage so elaborately that there is no danger attending the discharge ol
the effluent into this supply, it is claimed by some sanitarians that it ifl
unsafe to rely exclusively upon the continuous proper operation of whaler
filters and the treatment of sewage is also ne<H»ssury t ic

health. The subject is one of the most disputed f^ .;i*

today; it is destined to concern many cities vitally and to involve them
in enormous financial obligations if the advociitra of compulsory sewage
treatment have their way. The sanitar)^ engineer w^ho neglects to work
for the best interests of the public health falls short of the full disrhargti
of his professional obligations, but it is w^isc to keep in mind a fact stated
as follows by Engineering News: ''We know of many instances in which
business men distnist onginccirs and pin tboir faith to so-called ' practiaal'

INTRODUCTION

31

largely because of unfortunate experience with engineerH who

i to think that the question of co.4t wa» no part of their concern/*
Icgid clangers of attempting to discharge sewage into a amall
boily of water must be considered in the design of sewerage systems.
In Sammons %m. City of Gloversville, the New York Court of Appoalti
decided that although the city exercLied a legitimate governmental
power for public benefit when it built its sewers, it had no charter rights
to dii!>charge sewage into a brook in such a way a^j to injure the plaintiff's

Bds below the point of discharge. Even where a city has statute
kt8 to construct sewers emptying into a creek, whereby a nuisance
I createtl, the Alabama Supreme Coiu-t held in Mayor, etc., of Bir-
mingham r«. Land, 34 S. Hep. 613^ that the owner of a riparian farm below
,lhe newer outlet was entitled to damages. The Maryland Court of
ApjK^alK similarly decided the case of West Arlington Imp. Co. vs. Mount
Hope Retreat, 54 Atl. Rep, 982. The fact that a watxjr-coursc is already
jMtttaiuinak^i does not entitle other persons to aid in its contamination
^H>rovent those thereby injured from recovering from them damages
TOT the injury; Ind. Sup. Ct., West Munoie Strawboard Co, rs. Slack, 72
&i^K, liep. 879,

lie C4fcse of Waterbury, Conn., wiia of much intereet for many j^eara
} of tho protracted fight made by the city against building purifi-
lea^Q works in accordance with a decree of the Connecticut Supreme
I Court going into effect on Dec, 1, 1902. In one of the subsequent
lions in this litigation, the court i*tated that the construction of the
rbuf)'" aewers in 1884, in accordance with the terms of its charter,
lawful and that their construction to discharge sewage into the
fituck River gave nobody cause of action. The sewers could be
for that purpose without any inva-iioa of the rights of owners of
riparian pro{>erty below the point of discharge. But when the city
di^harged sewiige into the river in such quantities and in such manner
that it wtw carrie^l without much clumge to the property of a manu*
[iaoiuring company, thereby producing a pobhc nuisance to the com-
I special damage, the city was held to make a public nuisance of its
sy.stem. Each day such an unlawful act was repeated the
Hulfercd a freish inva^^ion of its legal rights, according to the

I

CHAPTER I
THE GENERAL ARRANGEMENT OF SEWERAGE SYSTEMS

It hiiH been pointed out in the introductory chapter that many of tho
troubles with early »evverago systems were due to an underestimate of the
amount of the rainfall reaching the sewers and an overestimate of their
capacity. At a later period another error of judgnxent waa often made,
which is causing trouble now; this was the failure to plan works capable
of extension on the original hues after the cities had grown much larger.
There is a limit, of course, beyond which an engineer is not justified in
making allowances for tho requirements of the futxu-e^ but the former
neglect to look ahead for more than a relatively few years hos recently
made very expensive works necessary' in a number of cities. It ia not
wise to place a heavy financial burden on the present generation for the
benefit of those to come, but if future expenses can bo reduced by careful
planning today, M^athout appreciable additional cost, such a course ia
manifestly the right one to adopt

One cause of the confusion that sometimes arises in oonsidering sewer-
age planSj is a failure to recognize that there are distinct general arrange-
ments of sewers and there are several distinct classes of sewers, each
having a main purpose.

CONDITIONS GOVERNING A SEWER PLAN

The general outline of a sewerage system is governed by two prime
factors, the topography of tiie city and the place of disposal of the srwagc.
The two are sometimes so simple in their efTect that the g^eml plan
to be followed is self-evident, but in other cases they have complex
interrelations that require protracted study before the best plan can bo
defi n i tely detej-rn iikhI , *

Influence of Disposal Methods. — There are three general methods i
disposal tljat affect tho design of tho sowers.

The first metliod of disposal is directly into a river or other bo<ly
water on the shore of which the city lies; probably tho Borough of
Manhattan offers the bes^t example of this, with it^ main sewers running
e^ist and west to numeTous outlets on the North and Kast Uivem.

The second method of dijf[iositil is to intercept the sewage and carry it

I The Ami ffi*n(«riil Hijirtinaicm u( if ill »ubj«FCi lu EagiUU w%* Ajipmfititlly'iu Bcrin«'a tS8l

32

GESHBAL AHHANGEMENT OF SEWERAGE SYSTEMS

33

to a iHJint in the adjoiniDg body of water where it will not cause trouble;
th« iDAy not b© necessary ut first, but in most cases it is inevitable if the
city i^ows &a rapidly as do most American municipalities, and attention
muat be paid to it, particularly to the future desirability of separatinj?
the house sewage from pnrt of the yform water. The Cleveland system,
«bown in Fig. 2, from EnguntTinq AVaif, March 28^ 1912; is an example
of this intercepting plan.

The third method of disjiositl is by »ome treatment uf the .sewage

Sh9wn Halted

iz'*'^^:'

Submerqed
^ Oufhf.

^^ Crib ^^^^f^^, 04^

\ ui '} — f 'J^ndaiid intercepting sewer system*

change it^s charjicter before it w discharged into a
tiuikes it neeoHKMry to deliver the sewage to treat-
inefii work,**, .suitable sitt^ for which are difficult to procure in many cases,
fmrtirulariy whore the country is well built up, not enough open land
pro|ierly Icteateti bi available in the oity, and neighboring towns object
to tiio phint b" in their liinitn. The separation of

•dorm wnU^rf run, often bwome^ finajicially advinaMe,

19 fta to permit the former to be discharged by sliort, direct lines into the
fiver, lake or bay nearby, and also keej) down the cost of the long sewer

^^

34

AMERICAN SEWERAGE PRACTICE

to the dkpoBal work^, and the dbpoBal costs as well. In the case of
combined sewers, the same end is attained by making provision at one
or more points for the discharge of the storm wattir in excels of a pre-
determined amount, through overflow weirs or chamljers into chiinnpU
or other outleta leading directly to the river or lake. The early flow of
storm water carries a large amount of organic matter from the ntreeta
into the sewera and takes into suspension some of the matter deposited
previously in the sewers, and its treatment is often considered as desir-
able as that of the house sewage.*

The design of the overflow chambers ia thus an important matter. It
may be found practicable to permit a large proportion of the sewage to
escape through mine of them in the early years of their Use, but later,
owing to a change in the character of the boily of water receiving this
excess storm-flow, or the greater imi)urit>' it may then poasens, its delivery
to the disposal works may prove desirable, Wliile it is unnecc^<sary in
many ciiscs to give the outfall sewer to the works a very large capacity
to provide for such future possibilities, owing to the h^nvy flxcd charges
such construction will cause, it is often desiralile to conisider future re-
quirements with particular care in planning the overflow chambers^
in order that their reconstruction or modification may not cause diffi-
culties in the operation of the system out of all proportion to the cost
of the work. ^

Influence of Topography. — The topographical features of a city aba^H
have a marked influence on the design of a sewerage system. In a larg^^B
city situated on a flat plain without any neighboring river or luke into
which the sewage may be tlischarged without elaborate treatment the
railial system may prove best. This has its most elaborate development
in Berlin, whore it was introduced by Hobrecht. The city is divided

^ The Loe»l Government BcuM-d of EagUtid goaerally liHi^Lirfo*] uniU rrtct«ntly thnt mtty
IficrMMve in th« flow In fombinvd oewcrs up to thrty? limtm thv tiomial <lpy-w«>i»Lhfr mtft
should bu treaiU?il like KuuiMs ftfwiij|:r» aud ih»t ux iidtJiUafi»l dtlulioiuA -
thrfitigh "Btorin-^itltcm" of itravcl, broken stDtic or clinker. lit iHo Hfih II'
Boynl Coinfui«iiiion on Sr-wnjo IMspoMiilt tbcso rt^^iuirotuc^ot* »rf ont>rM
rv<juirt*m(*ut« ahuald. wc think* bo luodiaod; th«-y arts, iu our ofiinion. i, ;
And exprricncic' biui fthown that spis^iAl Btann.*fiilUiT», which «re kept i^" *• <
not efficient, W> fiod ihftl the injury done to rWi^rs by the* di*ch«rt« uiio iheju, oi \urn<»
volumes ot slorm-«oiiriico chiefly ^rbea (rom tbn cxcmidvfs tunmtia of BuspundiKl nolidA
which »ioh lewnfe oomtnititt, nnd thjit thiNw Mdida rjtti \m VQ>ry rn
We tbervton reconkineodt aji •> ir«*nerAl rul«t Uiftt, (U Sfw^ciK)
fthtmld be providitd «t thr v^ '
•ftolV>-«»tier whirh en n not
l|lf» .^f,.......» "JMeh niAy b«' ,

ikwt mm Um» m

•boil' *fH» the oori

owitlow M the wurkw fthuu^ i

hm artmaffed so thnt it mil

«u«rm-Alt'" i»i4t lUjr *,»r.

pe^i' ti> ' ' •>!! of the >•

QKNERAL ARRANGEMENT OF SEWERAGE SYSTEMS

35

pEit4i Ji ntitnl>er of setitora and the sewage of each sector is carried outward
by pumping to its independent disposal farm^ or the trunk sewers of
^ or inore sectors niay bo oonnectcd to a farm. There were eight
in 1910. The advantage of this system is that most of the sewera
likdy to be of adequate capacity for a long period, and the large,
sivc sewers are reduced to their minimum length,

* • The sewage of each district is pumped through foroe muina to the irrigation
US, which, with such an arrangement, can he divide<l around tho suhurl»a
the oily. The water courses and, in part, the low ridges, form tlie hrnir^
&f the di^trict^y whose number has now risen to 12, and whose size varies
iween 072 and 2128 acres. The pumping st-ation is located at the lowest
%T*J po<8aibU% and in only one district is an intermediate pumping station
The advantages resulting from this arrangement are so great that
f tfl€raa0cd cost of pumping due to the division of the pumping capacity
uiumportiint and can be ooimter balanced by the greater security of
frprration. The overflow works, for which the water-courses of the city
I outlet ohannels, form an important feature of the system" {FrUhling,
[•'Die Entwassenmg der Stadtc,*' 1910),

In mo»t eases such an arrangement is rendered impracticable by the
i^nce of hills, water-courses and other topogra[}hical conditional
[J«tuUl}% mortfover, old sewers conijAicate the problem, for it is always
ble to utdke existing structures so far as practicable. Only in
mre eaacn does the engineer have an opportimity to design a complet'O
inrcragp jrystem for a large city, as was the case in New Orleans and
BAltimnre,
It ^re, where the sewage had to be taken 5-3 /4 miles outside

tie . treatment, it waa apparent that the storm water should be

Died H^parately, for there was no objection to its discharge into the
r-courses adapted to receiving it. The city is intersected

ins, which discharge into branches of the Patapsco River.

f thissc streams receive^* so much foul run-off that it has been cov-
Torcc; the others are open. The Patajjsco and its branches are tidal
iniK ol Ch(^apeako Bay. The drainage area was divided into 28
flktri«;t«i, and the storm-water drains in each one were planned inde-
illy of the rest, to fit tlie topography and arrangement of streets
t bort way. These drains were kept as close to the surface as possi-
1 cifdej* not to force the strwcrs so low that it would be difficult to
SD^t the houwQ with them. In one low-lying district w*here the
• was particuhirly diflicult, the plans called for raising
irul btiilding a drain to carry the storm water into the
M«i Hive?r instead of a nearer stream which was liable to have ita
miiHxl nonsiilerably tluring floods, a condition wliich might cause
pluifige of the drains emptying into it.
J rcnioval of the hotiso sewage was a much more complicated prob*

36

AMERICAN SEWERAGE PRACTICE

lem. Part of it comes Irom dktricts which are high enough to enable
the sewage to flow by gravity to the treatment works, but a large part
haa to be pumped. The contour line between these two service districts
was determined by two factors, the elevation at which the sewage musli *
be discharged at the treatment works and the minimum safe grade of the
outfall sewer from the city to the works. The accompanying plan of
the intercepting sewers. Fig. 3, from Engineering Record^ Dec. 5, 1908,
shows where the outfall sewer reaches the eastern boundarj'^ of the city
and is continued through it toward the wet^tern boundarj^ as a high-level
intcrcepter, receiving all the sewage that can be delivered by gravity
to the disposal works. The sewage of the low^-lying portions of the city
i^ collected by four interccptrng sewers, two of which contain small

Ffo. 3. — Baltimore intercepting sewer system.

pumping plants to lift the sewage enough to prevent a docp position of
these sew<T8, which ia undesirable on account of the high co»t of con-
atruction in d(»ei) trenches in water-lxtfiring soil, and the difficulty of
connecting the triljutary s*nverH sjitisfaetorily with dGei>lying inter-
ceptcrs. All these intcrcepters nm to a station containing ttvo pmnps,
each with a nominal rating of 27,500,000 gal* a day against a total bead
of 72 ft. These pum|>s force the t^ewage through two lines of 42-in. cast-
iron mains 45.50 ft. long into a sewer about a mile long, dinchm-ging by
gravity into the main outfidl sewer.

Between the arrangement of sewers in the Borough of Manhattan,
discharging l)Otli litomi water and house aewagc thnnigh lihort linodf
into the nearby rivers, through many outlota, and the jirrtingement at

aBSBHAL AnnANOEMENT OF SEWERAGE SYSTEMS 37

BsUtimore^ with Ita Bcpanition of the storm water and the sewage, ita
high iind low levels, puaiping stations, long outfall sewer and ela]>orate
09ira^o treatment works, there is an infinite vjiriety of cornhinationii
pmetitralile. In every case, however, the topography suggests the
natural drainage and the street plan exercisew a more or lean strong
modifying influence. One of the most experienced old-school American
engineers^ William E. Worthen, the seventeenth president of the
Amt'rioan Society of Cii^l Engineers, when he was retained to plan im-
pfjrtant sewerage improvements in Brooklyn, had oonjstructed a largo
relief map of the ilit<trict, in order that he might see the whole topog-
raphy «f the area clearly while considering the existing troubles and the
Tarious romodios for them. While such a map Is unnecessary in m04^t
catieiA, of course, topograph^^ Ls sometime-s far more important than street
piann. In every caj^e special attention should be paid to the low-lying
difltiicta, for it In there that the large^st sewers mast be built in many
ea9f», and the difficultioa of construction are the greatest. It may be
foM * ' " :ible to reduce such work to a minimum by constructing an
int - sewer at a somewhat higher level ami thiLS restrict the

coastruetion in the low-lying sections to small sewers only deep enough
to verve the prof>erty of that district.

Another influence of topography on sewerage plans, often overlooker i,
waa iUi' ! lows bv Dr, Hering in his report of 1881 to the National

Boaf<i • ' u :

*^Ill Oftiie of audden showers on a greatly inclined surface which changes to
a Imrnl below, thn sewerg on the latter will become unduly charged, because
a greater percx^ntagc fl<»\vs off from a steeper slope in a certain time. To
avtikl ildii uneven rer.t?ption, the alignment should, as much as possible, be
m amuigcd as to prevent heavy grades on the sloping surface, at the expense
of light cin<t» on the levels. In other words, the velocity should be equalized
as mufih as p<msihU« in the two districts. This will retain tJie water on the
idofica and increase its discharge from the flat grounds, thus corresponding
■Uire to the conditions implied by the ordbiary way of calculating the
^{Mictty of sewers. It will therefore bononie necessary not to select the short-
MSt line to the low ground, but, like a niilruml descending a hill, a longer
liklaiiee to Ite i^ttvpmeti hy the gnitlicnt. This does not necessarily imply
a limgrr itrn for the town, because more than one sewer for a

Uy it/'
I not her liecidcd influence of topography is shown where the con-
jfx and surroundingM of the city are such that it is advisable to
rombinofl sewers in all parts of the city down to the lowest
I'h will permit storm-water overflows to be used. This
. J ' d liy E. J, Tort for the neW'Seweragc works of Brooklyn.

Below thia contotir line, the storm-water sewers are nm at a higher level
lliivr ' ' I \o have a free outlet to tide water* and the

kiiu cts is pumped to points of disposal.

38

AMERICAN SEWERAGE PRACTICE

In some cities the revision of old sewerage systema has beeo coupled
with the protection of lovt^-lying districts against flooding, as in Wash-
ington. In the original plan for the improvements, two levees with a
total length of 4000 ft. were proposed for the protection of al>out 900
acres of water-front propert)% but later a large amount of filling of park
and city property and raii^iing of street grades was sub^ituted for the
original project* The city, which lises the combineti sewerage system,
now has intercepting sewers aroimd it, and a few through it in order to
take advantage of topographical conditions which enable the sewage
of the higher parts of the cit>' to be kept out of the low-lying parts. All
the tby-woather sewage is delivered to a pumping station which dis-
charges it thorugh an outfall sewer 18^000 ft. long into the Potomac River
alK>ut 800 ft. from shore. A considerable quantity of storm water
from low-lying parts of the city is also pumped at this station, but only
into the Anacostia River on the bank of wliich the plant is located.

After the most favorable location of the main lineia of sewers ha« been
determined, the de-sirabllity of minor ehanges of position in order to
avoid needless interference with travel through busy streets should
receive attention. The construction of a sewer in a narrow or crowded
street costs the community a considerable sum in indirect damages and
directly affects those having placesf of business on the street.

CLASSIFICATION OF SEWERS

Until quite recently there was considerable confusion in the terms
used to de^iignate diiferent classes^ of sewers. A classification is necessary
because it affords the only convenient means of discussing collectively
the features of sewers for the same purpose in different parts of a system
or in Lhfferent cities^ but the different classes necessarily run into each
other somewhat so that no dear line of distinction between some of them
is practicable.

House Drains, house sewers or house connections are the small pipe
sewers leading from buildings to the public sewers. Strictly si)eaking.
the house drain h the nearly horizontal piping in a cellar into which the
mnl and waste pipes discharge, but custom has extended the use of the
term to the house sewer. In some cities they are put in and tlie eon-
nections with the public gewers are made by plumbers, but in other
places the part of the work under the street as far ab the property line,
or oven the whole di'ain from the sewer to the hoiLse, is laid by tlie city.
Citj' construction is advocatx^d by many engineers on the ground that it
is necessary in order to prevent itijur>^ to the sowers where the con-
nections with them are made and to insure good workmauj^lnp on tho
drtun in order to '^'tig up tho streets to remove iris

cau^iMl hv \n)ov cri iL. Ou the other hand whure tt jml

GEK^RAL ARRANGEMENT OF SEWERAGE SYSTEMS

39

regulntiiios governlni; house drains are properly drawn and rigidly en-
forced hy competent inspectors, there has been httle complaint of the
work of private coutractgrs.
In most large cities m nmch trouble has been caused by the l>reakage
lof vitriiied clay pipet* in or near the place where they pass through walls
I thai a rule has boon issued requiring cast-iron pipe to be employed for the
{drain for a distance of several feet outside the walls. Even if cast- iron
yiipe^ are aHt?d, care must be taken to have them firmly supported so that
will not he cracked by settlinK. Where there is danger of a settle-
It of the foundations of the building, local conditiona must determine
|ihu b<wt eonstruotion.

The minimiun size of house drains is 4 in,, for smaller sizes are liable

llo become clogged frequently, but 5 in. or 6 in. sizes are considered

Ibcttcr practice by many engineers, the latter being commonly adopted

iln ihe larger cities. The niinimun^ ftdl for a drain is usually fixed by a

[city rcigulation^ and less than 1/4 in. per foot is rarely permitted.

{Where the house drain must carry rain-water as well as house wastes,

[city n^itltttions sometimes fix the size of the pipe by the size of the lot

and an assumed rate of rainfall. In New York^ for instancei the baaia

of ealeultttiou is a rainfidl of 6 in. per hour with the drain running nearly

full at a minimum velocity of 4 ft. per second. These figures lead to

LiuK in the case of buildings covering considerable area, and in

' +es two or more drains arc often run to the street sewer. The

cftpacttiest of pipes are discassed in Chapter II.

Oiring to the annoyance which may be caused by a stopptige of a houjse
drmln, juiit as much care should be paid to its location and construction
in given to a street sewer. It should run on a uniform grade and
l«lJAight alignment, if possible, and where a bend mii'^t be made it m
[fBnrrmlly connidered desirable to use curved pipe if the deflection is more
1 0 in* in 2 ft, Bome engineers recommend iuspectiou holes at every
in a huuse drain; these are shafts of small vitrified pipe rising
from a U?c in the drain, and they are objectionable because their weight
dten breakti the pipe below and their top is easily damaged by lawn-
Qum'cm and rliildren. In any case there should be a clean-out hole on
tbe drmn just inside the house, where a cleaning-rod or heavy wire may
be pushed into the tlrmn to determine the location of, and if possible
pmih along, any stoppage.

Tlwf house drain enters the sewer at a branch, if the sewer is pipe, or a
«Utit if it tj» masonry. Where the sewer is in a deep trench, a vertical
pipe tmlhbd a eliimney, encased in aV>out 6 in. of concrete, is sometimes
rtm up from every branch or slant by the contractor. It ends at a
tnilarm deptJi below the aurface, such as 13 ft. in the Borough of the
Bfr: ' ' '* - lie drain is connected to its top. In any case the
Aii^ e should not be more than 45 deg*, for the

40 AMERICAN SEWERAGE PRACTICE

splashing of the hot liquid house wastes containing grease on the cool
walls of the sewer is liable to cause a heavy, tough coating on the latter,
which reduces the discharging capacity, and this splashing will be less if
the sewage enters at an easy angle than at 90 degrees. For the same
reason, it is well to give only a moderate vertical angle to the inlet into
the sewer, and to place the slants ^n brick sewers in such a position that
they do not allow the house sewage to trickle over much of the wall
before mingling with the dry-weather flow. A one-eighth bend may be
used next the branch or slant in order to give the line a rectangular
position with respect to the sewer.

In every case, care should be taken that the house drain is so conr
structed that there is no danger of sewage backing through it into the
cellar.

Lateral Sewers. — The smallest sewers in streets are termed the
laterals, and the extremities of the laterals are termed dead ends.
Experience has shown, as explained in the Introduction, that preferably
they should not be less than 8 in. in diameter on a separate sanitary
system, for a smaller cross-section is liable to become clogged, although
in small communities 6-in. pipes are sometimes used with success.
There is a marked tendency to consider 12 in. as the smallest diameter
for a combined sewer or storm-water drain. Theoretically anjrthing
liable to cause clogging should lodge in the house drains, but theory is
not so goo<l a guide as practice in this connection.

Manholes affording access to sewers are described in Chapter XIV.
No sewer which is so small that a man cannot enter it should have any
curve or change in grade between manholes, as other^Tse cleaning it may
bo very difficult. Large sewers may be given such cur\'es and changes in
grade as conditions demand, but with small sewers the changes should be
made by channels in the bottoms of the manholes, the loss of head due
to the turning being comiHMisated by an increased fall in the manhole.
This increase is arbitrarily assumed by the designer, half an inch fall in
the whole length of the channel in the manhole bottom being an amount
often selected.

The depth of the laterals below the street surface should generally be
a^ little iL'^ possible and still give adequate drainage to the houses. This
depth varies i^roatly, for in a city like New Orleans few houses have
collars and tlierofore shallow depths are sufficient, whereas in Boston
and Now York iKvp collars prevail ami oonsot^uently the sewers must be
still lower. Whoro a s<»wer is laiil in a stnvt running along a steep hillr
sido, it S4^niotinio< has to ho jjivon unusual depth to receive the sewage
from tho lowor side. In suburban districts with houses set well back
from tho stri^^ts. it is not unoonuuon for a house to remain connected
with a iV'vs]HH>l orsubsurfaoo irrijjation system. booaiL<e of the impractica-
bility of making a workablo oonntH'tiou with the sewer which will serve

nBffBRAL AnRANOEMENT OF SEWERAGE SYSTEMS

jmacly neighlioriDg houses. One long swwer in a street ia often

e3C|>eiidivc than two short ones having the same total length but

Dlumrinir in oppo^site directiona. The long sewer 13 likely to have a

I nd to require a deeper trencli at its lower end. Where the

.:\t and the ground-water table close to the surface, it may

I neccsssary in order to give the laterals sufficient fall, to con^struct them

slow the water table; iu such a case, risers are aometimes run up so that

ho house drains can l>e connected to them above the ground-water level.

Tht* proi>er cajjacitioB and the minimum grades of sewers are diacuAsed

\ dirtttil in sul>a(xjucnt cliapters. It ia only necessary' to state here that

f true grade of a combined sewer or etonn-water drain is its hydraulic

There liiis been an unfortunate tendency to use for computft-

jfHwio of the invert or the crown of the arch as the grade of

uLii combined and separate sewers, a practice which hats led to serioUB

rmblc in some cities.

There ia always some uncertainty regarding the amount of ground

which will leak into a sewer and a large group of small buildings

{«choolhoase will concentrato at one locality a quantity of sewage

ych eauoot be foreseen. The velocity when the sewer is half full is

»t an when it is full, consequently, there b no greater probability

limentatton of solid matter. The difference in cost between small

of IS ia not great and consequently in order to

oiiteifi «ii les with the volumes of sewage which may

rwMiOAbly be cjtpectcd, and still have capacity for an occasional unex-

condition^ lateral pipe sewers are sometimesj figured as rumiing

fall when carrying the maximum quantity of sewage which it is

Eied will reach them. Some engbieers have continued thii* policy

" |iip(H M large a^ 18 In. have been reached and in computing this

> thoy huTC provided for a depth of only seven-tenths of the diameter,

-:■ ^ lies when the quantity to be carried ejcceeds the capacity

ind in each case using seven-tenths of the diameter as the

I of the hydraulic gradient. It appears to the authors to be more

to make allowances for such unusual increments in Bow when

itDiRg the maximum quantity to be provided for, bearing in mind

f she of pipe must be such as to provide self-cleaning velocities

conditions of flow, and to figure the sewers as running full,

Jthc separate system is used and a large storm-water drain runs

ft ntrt^it, it may be ver>' difficult to cormect the houses with a

Tal, and it is sometimes adv^isable in such cases to run a lateral

of the street fis in Washington. This places an additional

1^* j^trect, but it eliminates a large amount of troublesome

fk with «maU pipes croiwing the street, which will interfere with the

■ring f>f future ronduits. If the atrc^t is wide and the lots have a small

uDtagie, the double laterals may even bo cheaper.

m

42

AMERICAN SEWERAGE PRACTICE

While the position of the latorab in the street is influenced by local con-
ditions they are lisually placed in the center thus etniiUizing t!ie length
and cost of house drains whitJi are built wholly or in part by the abutting
property owners. This location favors a minknum depth of sewer to
provide proper fall for the house connections. As sewers are usually
laid quite deep in comparison with water and gaa mains, they should
be kept at least 6 ft, from the latter, if possible^ so as to avoid t he danger
of injuring them during construction. Where the line is on one siile
of the street and property owiicrs pay for the actual length of their hou^e
Connections, those on one side have a financial advantage over the others,
which can be remedied, where the drains are laid by the city, by aji^aum-
ing that in every case the drain runs to the oenter of the street.

6'VftSfaftH

,6''WtSkffl'b^

HaW [ Half

Section in [ Section in
Reduced Crodle Monimum C/odle<

8id« maaholea affardiaie »o«>eBS to the iftnitary sewer from tlto Ride tuit(*»(i (if the top at«
used in this form or conj»lruotioii.

Fio. 4. — Standard arrangement of separate sewers, Philadelphia.

In Philadelphia^ standard general seettond for installations on the
separate system have been adopted by George S.Webster, Chief Eng.
of the Bureau of Surveys. The relative position of all conduiU under
3 ft. diameter is shown in Fig. 4; the general arrangement /or larger
conduits ia much the same. Slants and pipes for hanse connections are
put in every 15 ft. The minimum thieknoHS of concrote l»et\veen the
conduit and pip© ia 6 in., except in rock excavutiou. With those aectionti
the tilling over the top of the coudait is at least 3 ft. deep. Many
engineers prefer to have thcifwrwersatone pttle of the drains, in urdor tliat
they may be reiiched readily; this requh'es a wider trench than where
the two-atory arrangement of Fig. 4 ia cmploytHL

Branch Sewers. — The lat<?ral sewers frequently discharge into long
br^vnches, which in turn dlHcharge into the trunk tiewers. Exporienoe

GENERAL ARRANGEMENT OF SEWERAGE SYSTEAfS 43

tddirrfttod thftt these long branches, which lie on the boundary be-
iiJ miisonr>^ construction, iire quite troublesome to arrange,
■r\s ill tlioir phmrt are as likely to arbe as in the design of
bo other classes. The reasons for thin are several In order to econo-
in the cost of construction of both sewers and houae drains, the
epths of the sewors below the surface should be as smtUl as possible, but
l«*r to rarr>^ off the aewage from the laterals the branches must
rily be deeper than local hoase drainage alone demands. The
le must bo steep enough to give an adequate scouring velocity and
lit enough to keep the points where the branches enter the trunk sewers
enough to allow the latter, in the case of combined sewers, to
r dr>*' weather flow into intercepting sewers. Furthermore
rs serve relatively small districts, and if storm-water is
by them, a material increase in the extent of impervious territory
ay make Mueh a cliajige in the maximum amount of run-off reaching
in short periods of time that they will become surcharged before
he [capacity of the large trunks is reached. On the other hand, branch
of Urge capacity but carrying small quantities of sewage are
iy to collect sludge on the inverts, owing to the low velocities. Con-
^ : T haa to nelect a size and grade which reduces the

. s tu a minimum. In suoh cases the egg-shaped

ij^ douictmies employed to advantage, owing to the small channel
|lt ihe bottom of the section, which usually has a radius of about half
> tniytimimi width and a total height of about one and a half times the
!■ width.

uy cajsoH it is impracticable to connect the laterals to the lower

lion of a branch without using very deep trenches for the lower parts

ilie laterals and their house drains, or else keeping the lateral at a

ihcT i*levation and allowing them to discharge into the branch sewer

a drop manhole, a special structure descrilied in Chapter XIV.

^choice between the deep lateral or the drop manhole depends

primarily on their relative cost, and in determining costs the expense

f deep huuse connections as well as laterals should bo considered.

It was pointed out by Dr. Ilcring in 1881 tluit an axiom of sewerage

I wtui that u sewer of A' timeti the capacity of another does not cost

tiam iw mucli money, and it is therefore desirable to lead as many

\ toeKher into branchen aa possible. This ako gives the laterals

' cnvdoi, 119 a ndc.

AncTthfT tiling to be considered with low-lying sewers in districts where

b^L Afo carried on wood piles was brought out as foUows in a

Lii . .,. ..... ^ew€srage of Hobokon, made in 1912 by James H. Fuortos:

^^l«ny af the lurge and fine buihlings in Hoboken rest vtpon woodwj piles,

1 tketm will rcinuiu safn and stahle *> long as the piles ary kept 8ul>rnerged

* th© unitirwl.^t "t^r ti' vi r I f tiie grouud-water level were to bo lowered

44 A Af ERIC AN SEWERAGE PRACTICE

l)ol()W tlio prcHcnt prevailing height, then trouble would be sure to be felt
in li ooinparativcly short time, by the rotting of the piles and grillages,
tho oruHhing of tlio timber and the settlement of the buildings. If all the
scworH and their connections were perfectly tight and would remain so,
thoro would ho little likelihood of danger from this cause in securing good
(l(H>p-(H'lIar drainage. I am quite certain, however, that sewers cannot be
niaintained in such a condition in Hoboken."

This recommendation is confirmed by observations in New York,
where the construction of subways and sewors has lowered the ground-
water level in places and comparatively new foundation piling has rotted
away.

Trunk Sewers. — The trunk sewers are the main stems of the sewerage
network; in snuiU cities there may be only one, but in large cities there
may be several, sometimes uniting where the general arrangement of the
system is that of a fan and sometimes discharging independently into
rivers, lakes or ])onds, like the trunk combined sewors of New York and
most storm-water drains cverj'wherc.

There Is, of course, a great difference in the design of the trunk sewers
of separate and combined systems. Where storm water enters into .
consitleration, it usually exceeds the amount of house sewage so greatly
that the oai)acity of the sections is fixed by it. The only influence of the
liouse sewagi^ on the design is to govern to some extent the shape of the
invert, in oriler that the channel for the dry-weather flow may be such
tliat the velocity during rainless periods ^411 be maintained within
tlesirable limits. The flow in sewers is discussed in the next chapter.

The si/e of trunk sewers receiving house sewage only may be selected
on somewhat narrower lines than the size of the laterals and smaller
br:uulu»s. because it is hardly probable that all these small sewers will
reooive more sewage than the exi>ected future maximum. Nevertheless
in many casi^ the maximum assumeii quantities are not more than
about si^ven-tonths of the greatest capacity of the sections provided.

Wlioro trunk sewers lie det^p and the branches discharging into them
would naturally be muoh liigher, well-holes are sometimes used to con-
nect the two. Tluse devii'os are deseribeil in Chapter XIV on special
structures, wliiili also gives a description of flight sewers, occasionally
riHiuircd wIutc a heavy i\ro\> in the grade of a trunk sewer is necessary.

A t\*;ini!c i>! dcsijin which shouKl be mentioned in this place was stated
as I'olKnxs in Or. llcriuij's report to the National Roiird of Health in 1881:

" ri'.c j;:!;i':;o!i :in»;lc of t>Mn crijinij sowers should bo arranged so that tho
J..ro.:.,'V. *»;' t%'\\ i»f t!\c two >tn*:iM\> bofon* jiMning is as noArly as practicable
t V. c n; I ' V. o . N r '. T 1 \ r r « i V. t * i c ! «. I . ^^o i n \ i ch \ t*l i v\ T >• i ii end o^i voring to overoame
;':.!' i^:..,'-.i;x^ ;:■. v;;r» . :uvi. Die less \\\o si.^t^ of I ho n^jxvtive streamsdiffer
rr.v; o'.i*:; x^tiu'r :l.i' v^»n^ cssi'r.Ti;»l is this vvnsidoniuon. An important
:V.i:..?i^ ,'. ;.;v.,':.o:;> :> :l;o n':;i::\o h.cv^ht of tV.o jvnning streams, f or unleas

GENERAL ARRANGEMENT OF SEWERAGE SYSTEMS

45

hia point b oonsidcred backwater aiid deposits may occur in one of thorn.
rh€«orctiojill3^ the joming sewers should be 8o shaped as to constantly deliver
Miewttge of each at the same level. To comply with thiK demand on all
dons is impossible, and it will suffice to comjider the ordinary flow which
daring nine-tenths of the time. The siirfat^e of the latter in the
1 1 bntnciica should be either the same for all, or increase* in height aa the bulk
1^^ the sewage become* less. In other words, the smaller sewers should join
^Hhe larger ones so tliat their ordinary flows meet at the sa/ne level, or so that
^^Bhe smaller sewer discharges at a higher level. When two sewers discharge
^^Bito a manhole opposite to each other, at points above its bottom, they should
^^be placi*d at different heights, or else receive a slight lateral turn, so that the
^^iill discharges do not directly meet each other,"

Tnmk aewers on the combined system are such expensive works ihat

very opportimity should be sought for reducing their cost legitimately.

ometimes this can be done by providing several points where surplus

E>nn water can escape through short channels or conduits to neighboring

lies of water, and at London provision hiia even been made to pump

s of this storm water into the Thames rather than give the long trunk

I the size needetl to lumdJo it. These pumping stations are operated

I engines, and are run only when the storm water must be handled.

ometimes the first cast of combined trunk sewers can profitably bo

where the cost of construction is not hea^'y, by employing a

lall crosjr-section and constructing another trunk sewer later when

f is needed. Where construction is expensive on account of poor ground

the presence of large amounts of water, or imposes a serious burden on

h#^ hu-«iiness of the streets in which it is carried on, it is usually advisable

the trunk sewers to servo the community for the entire period

c interest rates on the cost of the sewers make most economical.

|ften the most satisfactorj" method of keeping down the cost of combined

link sewers is to run them to the nearest bodies of water and draw off the

weather sewogeinto intercepting sewers near their lower ends. The

xtreme lower ends of the trunk sewers thus disdharge storm water during

while at other times the house sewage passes into the intercepting

rera* The methods of deUvoring the sewage into the intercepting

vers are cx|)lained in Chapter XVI, on the design of special structure.^

Intercepting sewers, or collectors^ are of two distinct types. The first

eives part or all of the sewage of the system above a given contour,

1 is employed either to ]M?rmit a reduction in the sixe of the intercepters

lower levels or t-o duHchajgc by gravitj^ the sewage from districts high

ftou k e pum pi ng u n necessa ry . I n t he latter ca^e lo w4c vel in ter-

ept- : fi are really trunk sewers although custom does not give

them that narnet are employed to convey the sewage from the low lands

Ebe pumping stations. The second type of intercepter crosses below
prunk sewers of combined s>*stems and receives the dr>^*vveather sew-
ctirried by them. By restricting its duty maixdy to the house sewage,

\\\ AMKRICAX SEWERAGE PRACTICE*

it o:*n Ih> kopt of n^lHtivoly snuill xsizo and the sewage can thus be con-
tliiot*Hl l\v it in the nuKst eoi>non\ical manner to the place of dispa^^aL
\\y a snital^le allowanoe in the ilesifrn of the s]>ecial structures for inter-
*vptinis tlie house s<*\v:h^\ the offensive first wash of the storm may also
Iv di\ ertinl.

Inlenvptors an* isivon capaciti^^ determinetl by the methods explained
in n^'M^tors V and VI 1 1. Thoy jjiMierally earr>' from 3CX> to iOO gal. per
Ivrs^Mi fr^MU a fH^pulation estnuaioii to exist from 30 to 40 years after the
date of the di^sijjns.

Relief sewers an* buiH to take pan of the sewage from a district where
the irur.k or intonvpthiir sewers an* aln^ady overoh arced or are in
dar.o^r ot Uwuun*: s*^. They may Iv u:^\i to take exoe-s storm water
wht>n* it :h:>vs:or.s to Min'harci* old s<*wers. as hapix^n? when the area of
'intj'H^rx ious '..v.i*i inrn\-^'^>s cn\itly or additional :orritoT>* is drain«i into
tl-.o-^* o:d :r.a n '.ir.i>N or they :v.ay Iv ir.A*io 'o :vr\-e consiAmly a ei\'en
*ii>tT:ir: sr.*; iv t^.>r.r.iv:*\i wi'h "he bnv/.ohos a:^d ';aToral> :n :t. so as to
n^s-ir-rl :ho si-7\i.v of 'ho Oi»ier :r;ir.k sc^wvrs :o h n»ore dis^iii": district.
}\:y*riiv..v .r. 'arp^ ii:\>v. r.i^;.s:':y ^.r. Kv.iior.. >how< -/t.a' r/jort' than one
Ti-^'.irf sk-^Tfttrr :v,.'i> OM^;v.;.C^.y !wi^r.;e r.ivo*Ar>- for a ir.vixr. ■.iis'iTict,^

The *v.ri>'r.i;:?.v.-. of Tiriof *^wo7s -.s :;o; :-.t\'^>«.sr'.:y ar. i^dT^non of any
OTTor V. : ho o-x:r.:u :\.v.-i> of a ss "ttoraci-" >>->■; <r.-.. As ai?OAHi>- s:a:<-d. it maT
iv t» jsi-^ ;;:;."ior s»v.-.-ii- ':.vvs', »-*.v.^.i.";ior.> io use r.s".hic st.'..s11 ir.ink sewers hi
i"r^i. \'isrt^s'',,'isr^ .:" ihr-rc > »v»r;N:i-;i-r,s":iic ^i »•■.:•■''; as to i.r.-:- .i:r«i30L in
vhi:h ihr i-.'y > ;V';x..M.'»"»v. i» .'.. f\:;: .i. if -ur.-.is iv-t:..: .vni rste d^-

TSf .'•:».•. .■•:' s:. ;«..ir:.;. s;-^-ir r.,:.-...r.c .:.:. -^sur i> r^-rrj^i it* c»ui]«;
■ oi;;':iJ. > s.-»7.;f:.:.!^ .jsrvi .r ,-*.:: a-: " T:< .■:^*: h-^rcf X a seweff
i» h ! .-• ^. i> : i?r' : : ^ . •' v ) m . : ^ v ..:«:. ; : <^c;x' > ."i js.- .tt;:^.-, . :. rrii T.' f n :• rai.T»T<r-

,-h.i;o.:it :»:»?. v ii.' '.^ :- .,:•: t-v .'; :.:•: ?*.:■.. •:*i*: -^.nc aciwii. Tbe
T'JiTMf > *. ;\.-^.r .i:if li..: :*.*', s/ :i«i;. s> niViV.I'.-s vJ.T'T. is .'i.'T^isiniiiJJT

v.».,i.. M i:.i'.-? :•,'■,■•• :. V.I. -.K .1 •.. <,«.■? s."fi«'>' jt- TiTssirt ^w«s.

p.. ; n ■■-.'*» . ' ^ .-- ' * • -..'■■ ■■■•■.!:* .1..- ri> '.-• iiM i> iwmiTTXiMi

I ..- »..-';-.i * . ■ !■ «■ :...-• • 1 • -.• .1 . *. ■• * nj.Tk.ii ^r^'mt

S... -,». ih. V - -■■:■ ■ ■ ■ ■« • ■ . -v • -^ i:^ t...r;r»f liiu ur

«^* ..^ .,...-...«■..'■ ■' '.• \ '.. ' ■ I •.•-■•■ t t , :xi,. -mnnff

1. n.-t «* •"iinl *-i«- 1* •■■ '■ 'Hi, l^ .ii*.-i. .:.•. r-..,. ih. «,'-%iN,tri ^.^r^rst;- S^'auo. UU: «Ik>

GBSBBAL ARRANOEMESr OF SEWERAGE SYSTEMS 47

• ttre moe^t fTt»qutmtly employed to cross under rivers, but occasionally

oeedod on outfivUs to iivoid the loug lines which would be required

I keep tins sewera on the hydraulic gradient^ or to make pumping un-

> In their donign it is necessary to allow for internal pressure, and until
lily cast iron or steel pifx^ has generally bet^n employed for them.
yith tl^ie development of reinforced cxsncrete, however, a new material
come available for pressure sewera built in the trench, which have
eooiitructed of noteworthy dimensions in Paris^ and gftill more
cntly rciniorced-concrete pipe of large i^ize have been made and tested
|tj ' '*,4 up to 90 lb. per square inch, by the Lock Joint Pipe Co.

1 previously encountered with such pipe under pressure

beea in the joints, hut in the tests mentioned (see Engiiuerin^
}((nt$^ Doc. 4, 1913) a special joint was employed in some cases and this
Dved tiirhl. Thia t>^pe of pipe is describctl in Chapter X, and has been
>d t (PC sennce in the Baltimore water works.

VLi tails at the ends of inverted siphons are described in

iptitr XV- In any case where such siphons are employed, care should
ten to provide blow-offs at the lowest points, if possible, and to
at, 3*0 far as practicable, coarse material from entering them. In
eoooection with such a y)rcs8ure sewer at Fitchburg, Mass,, for example,
& Ufice ^\t rhamlier with screens has been provided, and a blow-off
limDcli has boon built to the Nashua River,

Vwe^ oiains air n* sewers through which sewage is pumped.

Where «nall punii : ions are used to avoid placing sewers in deep

Instielittc, it Li often tieslrable to concentrate the lift at the stations, the
9mm^ flowing to them by gravity and, after being lifted, flowing
twuy Ify gmvit>% than avoiding the use of a long force main.

rhuEhing sewers are occasionally used in sewerage w^ork to flush out
jnter-^ourseH receiving sewage or to convey water for flashing to the
I of thf^ iintm to be kept clean . They are not sewers, strictly speaking,
%ler conduits* Milwaukee, Chicago and Brooklyn possess flushing
I of Uii? first class, A good example of the second class was propoeed
H. Fuerten in 1912 for u.se in connection with new sewers at
N. J- This phm called for large shallow rein forced -concrete
thu hoadfl of the flat trunk aewens needing flushing. The tanka
' ! with hiu-bor water through pipe flushing sewers built
foundations of the main sewers, a flap valve being
I tlio «nd of Iho supply pipe in rach tank* In this way the tanks
A on rising tidw and the flap valves will prevent the escape
the waler aa th«» title fall*. At the proper time on the falling tide, a

M I atieally and cpiickly to let the water run
1, the operation of the gat© being con*
by A float.

48

AMERICAN SEWERAGE PRACTICE

GENERAL DETAILS OF SEWIIRAGE SYSTEMS*

Grades.— Although the grade of the invert is usually meant when the
grade of a sewer is mentioned, in detennining the cross-sections of
combined and stomx-water sowers the surface of the flomng tsewago or
the hydrauhc gradient should be the controllmg grade. In the case of
separate sewers for house sewage alono^ this distinction is rarely important
and consequently is generally disregarded, but with combinwi sewers,
where the surface of the water in the sewer during heavy rains may have
a Bnxaller slope than the invdht, the surface gradient must be the controll-
ing inclination or unpleasant conditions may arise like those which
existed in Brooklyn, as mentioned in the Introduction.

The invert grarle i.*. the most important factor controlling the flow
in sewers carr>^ing only hoa^.e sewage, and in combined sewers while
only the dr>^-weather sewage ia flowing. As explained in detail in the
next chapter, the dope, », is ecjual to v^ /c'hr, w^here v is the velocity, c is
an empirical coefficient and r is the hydraulic mean radius or the area
of the cross-section of the flowing stream divided by the length of the
portion of the perimeter of the section w^hich the water touches. As it
IS apparent that at very low depths, there must be some uncertainty
regarchng the accuracy of the formula's results, some assimiption of a
minimum depth of the stream to which it Is applicable must bo made;
thia is tcJcen at about 0.8 in. in Germany. Lens than this results in the
Btrandiag of suspended matter on the invert until it is fiiished out by a
larger flow than usual. In tlie case of the smallest laterals, it Is inevitable
for them to be dr>^ near their dead ends at times, and a mere trickle
of sewage generally flows through them, so that the stranding of suspended
matter in them is common and they are often kept clean by flushing^ either
by hand or by automatic apparatus described in Cliaptcr XV, As a
result of experience and observation ^ American sewerage ^specialists have
reached a fairly imiform practice in respect to minimum grades for these
smaU sewers, which is explained in detail in Chapter IIL A rule for
the minimum grade much used in England is to make it equal to
1 /(5ri + 50), where d is the diivmeter in inches. In Gemiaity circtila
house sewers with a diameter of 4 to 5 in. are given .*ilopes r>f 1 :15 to I iSC
if possible; house sewers of 6 in. diameter, sIo|>g8 of I ; 20 to 1:60; latwid
pewerB up to 12 in. diameter, slopes of 1: 30 to 1 : 1»50, jmd from 12 to 24
in. diameter, slopes of 1 : 50 to 1 : 20(>. With cgg-shapod sections* the
minimum slopes are somewhat rtnluced; the prefernxl rangi* c' f

branch eowore of such a fM^tion is from 1: KK* to I :;j(H). In

^ la Ihli •iilirKi^DtAf. Ukft nuUiarv have oHopied mniiy af th
tuli|nnt «i am! iu KrOhlitift'a ** I>in KijlwA«f»nmr

1910,«ir' ivinc thnriMuluot tli« iavwitigBtioii* «tid

OBSBRAL AmANOBMENT OF SEWEHAGB SYSTEMS

49

the gradoa can bo still fartbor reduced, as explained in detail in
:!mptiT in.
it is not aways practicable to adhere to the standard minimum grades^
* flat topography, a high level of the ground water or the nectessity of
ping the H^wtigo may render it adv ij^iatile to rodueo the nlopes. The
iute minirimni for luteniLs in Oermany is about 1:250 for size^i
Up to 12 in. atid about 1:400 for those between 12 and 24 in,, while tho
^chm may sometimes bo reduced to 1: 1000; in the United States, the
tice id to establish certain minimum grades (sec Chapter III) for
Hi ' ' " -^ room, and if still lower gnido^ are required to have the
ix i for decision to the chief enRtneer'rS office- It Lh probable

OmI the larger quantity of sewage resulting from the more h!>eral ii^e of
wiiUr in the United States account? in part for tlie adoption of flatter
jjickis for small sewers here than in Germany.

The maximiun limit for grades has 1>een less discassed in the United
Statos than lias the minimum limit, but it h an important matter, par-
■iy with combined sewers and storm- water drains, where high
rdoctticn of discliargc may cause tho svispentle*! se<liment to injure tho
[iv«irtH and walL*. In Clermany the maximum for small house drains is
nbout 1:10, for f>-in, house drains about 1:15; for laterals al>out 1:20.
rbc drawback of steep slopes in small sewers is the probability that tho
iter will flow off so rapidly that the lai'ge floating matter will become
I on the invert and wiU not be dislodged by the next wave passing
^ ilown tho eew^er. In Hmall sewers it is praoticable to avoid these steep
gniilfai by u.-ung tlrop manboles, and on branches and trunks by using
light ncMnOT^; these special details are describe<i in Chapter XIV.
Titruing ftHide from these grade relations, the invert of a long aewer is
By a concave cun^e with the steeper part at the smaller end. If it
iihKtfed to havt? the hydraulic grade lie paralleh^'ith the invert and at the
mtxm time have tho sewer run full, it follows that a part of the sewer must
be under prcMsnre during storms, as shown in Fig. 5, the amount of the
prvvniro being determined by tho position of the hydraulio gradient*
it ia dosirod to avoid thls^ the computations must be made with the
. boftd luidod to the invert slopes which will result in some sections
' running only partly full, or the invert must bo dropped from
ne, Fig. ft, or the cross-^^ier'tion must be widenetl. Dropping tho
roK'c« a loss of totsd avail AJ>Ie fall, but it can be arranged to give
tJiati with the continuous invert if the dro|i8 in grade are
iHjj inlets of tho larger branches, as shown in Fig. 7, Such a
avoids a rediu»tion in velocity in both the branch and main sewer,
vith low depths of sewage wnon solids are
; . As alreniiy meiiti(jned, it is practicable
tij .. T iic velocity in the branch by giinng the latter a suitable

olr,*i..-.* ^.v-.. liie invert of the main into which it dischargee, but
i

50

AMERICAN SEWERAGE PRACTICE

this arrangement does not help the unfavorable condition in the main
sewer.

A special condition arises in combined sewers where there is a relief
outlet. When a large amount of storm water is flowing and the outlet is
in operation, Fig. 8, there Ls an increase in the hydraulic gradient for

Eaeess Head-. — — ■

Fi9.a.

I

HydrayhcOrodJ^^^^

A.

Fig. 9.
Figs. 5 to 9.

some distance above the outlet. Moreover, in the part of the sewer
affected by this change in the hydraulic gradient, the entering branches
are also similarly affected and there is a corresponding general increase in
velocitj'. This fact b< rarely taken into consideration, nor an imfavorable
consequence of it if the sewers are not kept clean, viz., the picking vip and
sweeping along of sludge previously deposited above the outlet.

CBNBRAL ARRANGEMENT OF SEWERAGE SYSTEMS 51

A ffwiuent caude of coagestion in a branch sewer, and its attendant

I»un')uirgt\ is m<licaied in Fig. 9, where ao increase in the elevation of the

[branch and its tributar>^ lines is impracticable on account of the local

peondttionjs. The surcharge of the branch can be avoided in this case by

^ k sewer, as in A, or it can be at least greatly reduced by

r section, as in B, which will lower the hydraulic gradient,

[It is also poaaiblo to give the branch sewer a larger section, high and nar-

> mul thus reduce its hydraulic gradient, but this is expenjsive and it

_^ prove befit to build the lower stretch of the branch very carefully

rith this object of making it carr>^ internal pressures at times.

In hiying out a combined sewerage s>'stem it is evident from what ha^

[boeci aaid that it is usually first necessary to determine the minimum

WHBible elevation of the siU of the lowest relief outlet. This will

bit! the elevation of the trunk sewer at that point to be estabEshed, and

from that elevation the grades of the upper portion of the system can be

.workeil out. The best location of the various linos can only be deter-

^mroed by a number of trials, in many cases, and the failure to give proper

des and hydrauUc gradients has been the cauise of much of

I < tory service of sewerage 8>^stems. The work is not unlike,

I in mtxw respects, the location studies of railway lines, which have also

|iieQtly been hurried along, to the great disadvantage of the sul^sequont

ittton of the roads.

lelief Outlets.— ^Relief outlets for the escape of storm water from large

into nearby rivers or lakes are an essential feature of any system of

[ecNuhined aewem, for otherwise the trunk sewers would require enormous

In rare cases, as in New Orleans, it is necessary to collect

ip all the storm water and under such conditions a separate

ipstem with indr?i)endent drains for removing the rainfall is tlie only

, Mitition of the sewerage problem. The purification of all the rain-water

[of A city has never been considered necessarj', and the problem is to

Illation of the house sewage with rain-water is desirable

ie irmy be discharged through the relief outlets.

ThiTO wiU be some sewage escape into the river or lake whenever there

ii m dueharge through one of these storm overflows. If the sewers are

na% kept dean, the amotmt of organic matter which is discharged in thin

will be higher than otherwise, because the scouring action of the

water in the sewers will sweep it from the inverts where it has

Itttlled during dry weather- But as many rainfalls will not yield enough

ivrntfT Uy bring the jrtorm orv^erflow into service, although they will increase

^ih^Aow to the rteweni enough to take up some of the depowit^s on the inverts,

^rr»nt that with well-designed and built sewers, the imcertaint>^ m

jL-gree of dilution of the house sewage during heav>^ storms will be

f usimportiint in most tmem. The relief outlets do not usually discharge

often tQcmgh in a well-deeigiied flystem to make the amount of organic

^

62

AMERICAN SEWERAGE PR ACT WE

matter oscapinpt through them into tho river of significance as respects the
conditi<jn of the latter.

There has been a great difference in the ratio of the storm water to^
house sewage atlopted as the basis for the design of the roUcf outh>Ls,
It is naturally larger when the outlet discharges into a small 8lufiiftiah
stream than where there is a larger body of water to receive the excea
quantity. If the outlets are along a river and it is more desirable to koojj
its upper course imcontaminatad than its lower course, the storm overflov
along the latter* should be much larger than the others, even though thii
makes it necessary to employ larger trunk sewers tlian would othorwij
be necessary between the first and lost points of relief.

The value of the ratio has ranged from about 2 to 8. The phenome
that take place in a sewer during the period when the overflow is in servic
have not been investigated so fully as is desirable. Ah already exiilainodj
there is an increased velocity of flow when the outlet begins to discharge
and this results in a somewhat larger volume of sewage continuing m
the trunk sewer than the usual computations make allowance for. Further-
more the discharge of a weir parallel to the thre^wl of the current may no
be so great as when the weir is at right angles to the current*

Numerous relief outlets have the dual advantage of keeping down ihd
size of the sowers and discharging the excess storm water at severa
places rather than concentrating it at one. The cost of the outlet conduit
from the overflows to the points of discharge, as compared with the cost
of --sewers of different sections, will afford a useful guide to the best numl>er,,
Old 8ewers and the channels of brooks can sometimes be utilized
advantage as the outlet conduits.

The design of these overflows is descril>ed in Chapter XVI-

The discharge over the sill of a relief outlet de|>ends on the elevatic
and length of the sill, the shape of the outlet and the dimensions of tl](
main sewer above and below the ontlet* Inasmuch as there is no <
experimental knowledge of the discharge of weirs parallel to tlie dire
tion of the current and other conditions of the case are unlike tho
favorable to fairly true results from the use of the standard formulas fo
weir discharge* (which ai^ discussed in Chapter IV), Fruhling advisee fo
use in computing the discharge: Q = ihk^^^ where Q is the quantity
cubic feet per second* b is the length nf the sill in feet and h in \' 1|

in feet of water over it. Another metho*i of estimating the di a

given in the chapter on the dtwign of relief overflows. It is more elaboru
but whether it gives results which approach the truth mon* closely is \
matt<;f of guesswork in the abseni*e of reliable exiKjriraental informalic

1 ^* Ho hmd bcfin iTyinff to grt informittioa wilii re«p»rd lo •ouic of Uir limit ovcrflaw^ on i
•eircTB in ^ ' . ' *' '^'^ ♦- - 1 *' -«■■* ♦- ' -^tntl it Y»tfy .|.*'5....i*

ably lu«bL: .,.» -- . ..: :.. -, - i- ^ of tJiw ovrr

GENERAL ARRANGEMENT OF SEWERAGE SYSTEMS 53

If the rdiof conduit is so designecl that its lower end is completely
eloiscd by high wttt^er m the river or lake into which it discharges, the
hydraulic gradient of the conduit should be investigated to make sure
thiii ba<^king-up of Uie wuter In the conduit' will not interfere with the
free action of the weir*

Below the relief outlet the trunk sewer carries a smaller quantitj- of
sewage than above it, and, with the 8ame grade, it may be given a smaller
ercM»^cciion. With an increase in elevation of the sill of the overflow
thiire is an increase in the quantity of water which remains in the trunk
jwwer. A long sill is better than a short one for regulating the quantity
of water which encapes and^ conseciuently^ the quantity which remains
ill I he Hcwcr,

If. for any reason, the sill of the storm overflow must be placed so
low that the floods in the river rise above it, but not to the crown of the
ik «ew€r, the discharge of the overflow will then be checked. There
no published obsen^ations of what the discharge will be under guch
eonditioDs, but from Hers<;hers diiaoussion of the flow over submerged
weirs (Trans, Am, Soc, C. E., XIV, 194) and adopting only two-thirda
of his quantities, the volume of sewage escaping from an overflow under

eh eonditiona will prol>ably not fall below an amount given by the ex-
sion Q = nbIP'\ whei'e Q Is the discharge in cubic feet per second,
( h the length of the sill, // is the depth of the sill below the water surface
in the sewer and n h a coefficient taken from the following list tuid
ikpDmling ui>on the ratio of A, the depth of water in the relief channel
from the surface to the sill, to H.

,n

0 1

0,2

0,3

2 1

0 4

2 0

0.5

0 0

1 A

0,7
t I

uorio huviiig iaciliiiw tor lunking nuch cxjieriments
iri' ^xiniately coefficients which may be safely used for

lit lid suiwnerged weirs like those used for relief outlets, the in-

ti^iii. All! prove of much practical value. Until such invest tgatioua

wte mAtle, iiie designer ma^it fix the lengths of the sills by the methods
to*' ' *r others equally approximate.

y uxcy Studies. — In nuiking the preliminary studies of a syst-em

of HewcTR, it i« nomctimos customary to ase ntcrcly tables of the discharge
dt mswetH laid on a gratle of 1 per cent. Tables 3 and 4 are examples,
ImmA an a Viiluc of n = 0*013 in tlio Kutter formula, cxplaine^i in the
n*" ineors prefer to use such tables and a slide-rule

I" - Ml diagrams like those given in the next chapter,

iiid la illustrate their use m well aa to introduce at tins point some of the
m*^~ - Tn\ prtiblemf* arlning in sewerage work, a few oxamplcti of
|»r studiw (adapted from FtiihUng's "EntwEaserung**} arc

54

AMERICAN SEWBHAGE PRACTICE

given here. The basic fact to be kept in mind is that velocities and Ah
charges vary about as the square roots of the grades.

1, A sower 1476 ft, long with a fall of 6.56 ft. must discharge 4.01)7 ml. I^
per second; what should be its diameter and velocity?

Tlie average slope is 6.56/1476 = l/225» The Ul)les arc prepared ftH
slopes of 1/100; velocities and discbarges for other slopes vary as the squa
roots of the slopes. The discharge on a slope of 1/100 corresponding
4.097 sec-ft on 1/225 is 4,097 x/(225/ 100), which is readily foimd by
slide-rule to be 6.15 sec.-ft. If it is desired to have the sewer run full whe
discharging, Table 3 indicates that a 16-in, circular section will be correclj
and the velocity will be about 3-1/2 ft. per second. Egg-shaped sections r
too expensive for discharges as small as this. The velocity with ^niaJk
discharges may be found by dividiog the tabular velocities for the dtfferea|
depths of sewage by \/(225/100). It is evident that the velocity sinka to
2-1/2 ft. when the sewage has a depth of less than about 5 in.

2. The 15-in. sewer of Ex, 1 discharges 0.053 cu. ft. per setK)nd during i
weather into an egg-shaped sewer 69 in. high on a grade of 1 : 1200, CArryin
Q.88 sec.-ft, of house sewage; what is the best way to prevent backing-u^
of sewage at the junction?

Tlie discharge of the main sewer with the same depth of fiow and a slop
of 1: 100 will be 0.88 V( 1200/100) or 3.06 sec.-ft., which Table 4 shows wil
fill less than 0.1 of the depth of the section or, say, 6 in. In tfie same wajj
the depth of flow in the 15-in, sewer with 0,053 sec.-ft. may bo fourui to \y{
less than 0. 1 of it« diameter, or, say, 1-1 /2 in. Hence, i&s a first approximation
it may be assumed that the invert of the later almost be 6-1-1/4 =- 4-3/4 j
above the invert of the main branch to cause the surface of the dewage in th
two sewers to be at the same elevation. This results in a loss in the invr
grade in the lateral, which is not likely to be of importance except where (
available fall or slope is restricted. The discharge of 0.053 into 0.S8 sec.-ftj
will cause only a trifling increase in depth and loss of velocity \i\ i
sewer- After the general layout has been worked up approxini
elevation of the branch sewer at the junction may be readjusted by th« imu
accurate methods explained in the next chapter.

3, The main sewer of Exs. 1 and 2 is assumed to be two- thirds
what will be the effect of this condition on the lateral?

Two-thirds of 69 in. is 46 in. ; (46-4-3/4) in. must therefor© be taken as t
total drop of the invert of the sewer in obtaining the grade for eoraputifl
the discharge during such oonditious. In other wonls, instead of a i
of 1/225, which is proper for cakndating the discharge of dry*weather i
age, one of (6.56-3.44)/ 1476 must be used.

4. In the main sewer, 656 ft. below the junction of Ex* 2, there is a rell^
outlet with the water on its sill 33 in. ab«jvo the invert during
what effect will it have at a point 2132 ft. aUive?

This ni^ be approximately solvtnl by dividing the 2l32-ft. leagth idtj
Mineral parts and assuming the hydraulic grndient to be oouMtant in
stretch. The starting point is the eknaticm of the water on the sill,
Tlie sewer flowing full will carr>- 211 v (100 1200) '^ 61 sec.-ft. As
outlet is approached the hydraulic gradteol increaiies, as mentioned <

GENERAL ARHAmBMENT OF SEWERAGE SYSTEMS

55

at thf* upper end of the outlet thifl qunDtity of sewaj^e is carried in the bottimi
Xi uu of the section, or at a depth of about 45 per cent, of the height. T]\e
dwrhfuge of sucii ef^-sbaped sewers nt dtfTerent depths, as will be explained
in Chapter II I ^ varies about as follows:

O.l 0.2 0.3 0.4 0 5 0 6 0 7 0 8 0 9 1 0
0,02 0.07 0 15 0,27 0 42 0.58 0 75 0.92 1.05 1 00
0 41 0.01 0.75 0,85 O 1»5 1.05 1,08 1.11 MI I 00

^cbftTf?'

^Velocitv

At a depth of 45 per cent., the discharge will therefore be about 37-1/2 per

cent, of the discharge of a full seetion at that velocity. Therefore ftl sec.-ft.

™^ divided by 0.375, or 162,7 sec-ft, would be diseharjced at this velocity were

Plthe sewer fulb The hydraulic grade is, therefore, (162.7V21 LI') (1/100) =

■^ 1,/168» at the outlet. The leni^th of the sections into which the sewer is

fiubdivided to ascertain the hydraulic j^adicut, nmy be taken of any lenj^th,

as 164 f t , for instance. Thus, by the methudn just explained, the heights

of the points on the hydraulic gradient will be found as follows:

(hitlet

= a3.o

Point 1.3:j.0 + 12Xie4{^-^} =43.1
P.int2.43.1 + 12xm{^-^}=«.7
Point 3. 46.7 + 12X164 {^-1^-^1=47.5
Point 4, 47 6 + 12 X 164 {^J---^^} =48 7

Point 5. 48.7 + 12 X 164 (^^-^}- 49 8

It h evident from these figures that the effect of the outlet extends far

J»ave the 2132-ft. stretch and also affectiS the branches. The curve is so

k lliat it IS unoecessar^' here to calculate more points on it; for approxi-

purx»ose it will answer to assume 1/(12 X 164) as the average grade

' Uie remainder of the stretch.

5. A flow of 44.14 aec.-ft, must be carried by a sewer with an invert grade

\fil 1 : 0(*0. The height *>( the sewer connecting with it abo%^e must not exceed

j8 in., owing to the low elevation of the surface, and there must be no internal

What egg-shaped section should be selected for the 1:900

Sin lie disehnrges are proportional to the square roots of the slopes, a

Itscharge of 44.15 sec.-ft. on a 1:900 grade is equivalent to one of

,15% (900/100) * 132.45 seo.-ft. on a 1: 100 slope. Table 4 shows that

fiO^in, arrtion will c?4rry this quantity, but the latt-er will require such a

' pruptirlion of the totttl capacity that there is danger of placing the next

ftve, under an internal pressure of 60 — 48 = 12 in. To avoid this

66 AMERICAN SEWERAGE PRACTICE

it id better to employ a 6^in. section running two-thirds full, that is, with
the sewage at an elevation of 46 in.

6. Owing to topographical conditions, a trunk sewer must have the pro-
file shown in Fig. 10. What are the cross-sections and hydraulic gradients
for the given invert grades and quantities?

The computation begins with the lowest stretch of sewer. The equiva-
lent discharge on a 1:100 grade is 204.82V(1000/100) « ^04 sec.-ft., an
amount so large that an aqueduct section of the semi-elliptie, semi-parabolic,
segmental, horse-shoe or other type, described in Chapter XII, will be
preferable to the egg-shaped, which would have a needlessly great depth,
and consequently expense, to be able to carry such a quantity.

If the next stretch were to run full with the quantity stated on the profile,
it would operate under the head due to the hydraulic gradient a6, which
would probably be continued farther back up the line. In view of the abun-
dant grade, the alternative arrangement at a, with a drop of some sort, such
as a flight sewer or well-hole, is preferable. The invert and hydraulic

It 1000

Alternative Ran
at*a?

Fio. 10.

gradients are determined by trial, assuming for a first approximation a
60-in. section and that the lowest stretch is a scmi-elliptical section 90 in.
high. Then

1 /1148.3_90 , G0\ 1
48.3 \ '40 12 12/ "44

1148

The volume of water will be 175.16v'(44/100) or 116 sec.-ft. on a 1:100
grade, which corresponds to a section between 54 in. and 57 in. high. If the
latter is chosen the hydraulic gradient will remain within the sewer even
with the next section above running full.

Either ge or cd can be t^ken as the hydraulic gradient for the next stretch.
In the latter case the sewer will require a somewhat smaller cross-section,
but the upper part will he subject to an internal pressure of an amount
depending on the height of the cross-section of this stretch, which it is there-
fore desirabh' to ascertain. An egg-shape<l section, with a hydraulic gradient
coinciding with tlie crown of the sewer r//, will be assumcfl. The actual
discharge and slofKi are equivah'nt to 158.92V' (800/ 100) = 450 cu. ft. per
s(HH)nd on a 1 : KK) slope. This ciuantity is beyond the scope of Table 4,
but with th(» help of Fig. 27 of Chapter II it will be found that a section
about 94 in. high will suffice. If it is assumed tentatively that the hydraulio

GEKERAL ARRANGEJ^BNT OF SEWERAGE SYSTEMS

67

gnulieni of cr u I :R5, then it. will he fo\inrl by the method already frequently
foUonrod that & fM^otiuii 03 m. high will be satisfactory^ to which a grade of

1_ /5249 94 _ 63\ _1_
4.9 \ 150 12 12/ " 86

524

oorrcsparidji, wLich agrees closely with the assumed grade. The excess he&d
pifDo ••-mill pressure at e is, thereforp^ 94 — 63 = 31 m,

ii nxi to avoid this internal presavire, the stretch niufit be designed

[ the baffcts uf the invert grade, in which case the discharge on a 1 : 100 grade
Ik 171.28 V(150/100) = 211 sec-ft., calling for a6&-in, sewer. In thia case
tliere will be a lowering of the surface of the sewage in the top stretch of
rer, as shown in the illuHtration.
7, A htorm-water o verfl* »w i8 located as shown In Fig, 1 1 ; what is the length
"1 if the overflow Li assumed to come int^ operation on a fivefold
»f the dry weather sewage?
'J ties of sewngo and the invert grades are indicated in Fig. 11;

Ithf^ f in parent hc^^es are the quantities during heavy storms, while

|lhe^ «iiAiier numbers are the quantities of dry -weather sewage after a five-
fold dilution. Sewer V has to carry, before the relief outlet oomes into action,
L13 4- 2.90 -I- 3.9f» « 1L02 cu. ft. per second, consisting of 1.84 cu, ft. of
cQthiT sewage and 9. 18 cu ^t -f ^torra water. This quantity corre-

W* 42/19' i'$S

IF

f

m,60/40' f 200

IK

im(^M)34c

$0/^40: tm

Fio. 11.

Spf'ffwtiy from 0>i^rfhw

Qvmrfhw

to 13.03 sec. -ft. on a 1:1(X1 grade. If the hydraulic gradient is

a«^ provisioruUly to bo parallel to the invert, the sewer will need a secv

[litiii b«ytm*«!n 21 in. and 27 in, high. Owing to the influence of the <iVcrflow

, tf ^ • - nulic gradient and to the entrance of another bninch a little

n t whcrt! ih« line terminates in the diagram, the sewer wris given

ii»ns rec<jrded in the illustration.

m. sewer K, the 11. U2 sec.-ft., or the corresponding 13.03
<lc, take up about 18 in. of the height of the Hfrction,
'•n of the sill of thf* relief outlet. If ifitertial pressure
Uf i>e avoided in sewer V, the length of the sill must be such that all the
lus waUt will flow over it l>ef«jre re^iching a deptli on the sill of 36 —
18 in. The l#?iigth of the sill is determined by the formula alreatly
nrd under '*n^ljef otitlels," Substituting the quantitif?s of the present
lln Ute fornMila, givcti h = 197.37 -r 4(18 -^ 12)* * ^ 26,H ft,, m the
nilb wltich should have a l:l4»>slope, corresponding with the
CTK' <*wcr. A sliorter sill would bo likely to cause an internal pres-

68

AMERICAN SEWERAGE PRACTICE

aiire in sewer V, with a oorregponding rising of the hydraulic gradient and
an increase in the lunoiint of water flowing thro^igh aewer V,

Sewer Sections. — The problem of the4e8ign of niasonr>^ sewers jt^ not
solved with the detcmiination of the reciuired c^irmnp capacity, hut
inchides a aumbor of other features which may be of considerable
importanco.

The raoet economical shape for the water-way cross-section can only
be selected after oareful consideration of the spe<iial conditions imposed and
the relativ^e merits of one type as against another to meet these sjjot^ial
conditions. While the circidar cross-section has been Ui*eil for a large
number of the niasonx}' sewers constructed in this country* there ha** been
an increasing use of other forms such as the horse-shoe, semi-elliptical
and rectangular sections. In tlie older combined sew^erage systems con-
8truete*i previous to 181)0, and built for the most part of brick for sizes
above 24 in. in diameter, the egg-shaped cross-section w*as frequently useil,
but since that time the extended use of separate systems has caiu^cd it
to decrease in popularity. The old Massachusetts North Metropolitan
System was a departure from the practice of the time in that it included
such types sjr the CiOthic, catenary and basket handle sections.

The general adoption of concrete for masonry sewers has brought about
a mom extended preference for the flatter t>i>es of inverts on aocount of
their being more easily constructed than the inverts of circular or egg-
shaped sections.

Aside from the hydraulic properties, such considerations as the mot lio<i
of construction, character of foundation, available space and stability
may be instrumental in determining the best tyjic of sewer section to
adopt for a given case.

The selection of the proper tluokneas of ma^^onry for a given size of
sewer, unless determined in tlie light of exi^erienec with similar structures,
should be the result of a careful consideration of the fonres to be en-
countered and an analysis of the stresses as delerrnin«Hl by the bpsi
avaihible methods* Thia applies particularly to the larger sewers, 0 ft.
in diameter and over.

A study of existing sewors is one of tlio beet gmdea t^ safe construction
although not netjessarily the tnost economical conHtruetion. Empirical
formuhis foundofi on experience have some value but should not be
depended upon without an adiKiuate aual>i.ical check.

The proper selection of the materials of conMruction involves not only
a On: n of the cost of one material with that of another but also a

eon u of the relative wearioi^ qualities of the nvulerialH. This is

Bpociaily true of the materials used for the lining of the invert.

In some localities the erosion of sewer inverts hat* Insen a serlotia
problfitn responnible for the failure of the entire structure* To resist
this wear, a lining of vitrified brick l\m been found satiafactOTy*

QESBRAL ARRANaBMENT OF SEWERAGE SYSTEMS 59

fhwera are subjected to the action of ejctcmal forces due to aurfacc

trarmmittcd tlirough the backfill and to the pressure of the back-

uiM' I If. Surface loads may be divided into live and dead

Ti r includes such loads as locomotives? and other rail-

Tosd rolling; stock, road rollers and he4ivy vehicles ; the latter includas loads

ImiEi pilfis of lumber^ brick, coal and other materials commonly stored in

oommercial and manofactmng district**.

With the advent of reinforced concrete has come a greater need for the

EFal ansl3rsis of the masonry section for large sewers. With sewers
trueted of brick or plain concrete, the sewer arch if properly designed
' " t(d only to compressive stresses and depends large!}^ for it*!
nil the ability of the nide walls or abutments to rcsis^t the arch
vt.< With reinforced concrete, however, the siructure as a whole
I iovert to crown can be designed to resist hea\y bending momenta
md wet nsi a mouoUth.

Hi' *" 'd '* clastic theory^' presents the most rational and prac-

tifsiil/i for the ajialysis of sewer sections. The method of analysis

liiicler this thcor>' ns desiTibeil by Turneaure and Maurer in *' Principles

Risuifurced Concrete Construction*' is one of tlie siniplest and best,

for AD analysis of the structure as a whole» particularly where the

ta to be built in compressible soil, the method developed by Prof.

W. French for the authors is preferable.

Aliiiotigh the previously mentioned aids in design are of the greatest
there must be beliind them all sound judgment coming from
if the best results arc to be obtained,

DEPRECUTION OF SEWERS

system represent? the investment of a large amount of
moneir^ umtiUly rausi^d by Issuing bonds. If munieipalities paid ajs much
itlAiliioci to financial accounts £us private corporations do, the present
09 d the «jwemge and other public works would be ascertained from
! |0 iimi!| just as a railroad company revises its estimates of the
|iLH physiciil property. The City of New York» in an en-
offset its bonded and other indebtedness by a statement
if Ihe Bctuai worth of Its property, carried out in 11)13 a valuation
the newerM of Manhattan, by methods described in Engineering
Vnrt, Jao. 8, 1914, by Otto Huf eland. The system thus valued was
bi tli< <*nih centuT}' and was built without much public

ui ' when a lawcamo intoo|i«ration that re<|Uii*ed the

r plaiiH for stjweruge districts. Even aft-cr that date it was
fore any comprehonsivo plans were prepared, and as a
rmftlt Iff thia condition many of the sewers cons true teil qmUy recently
I by no niisuns of the cafwcity or type which the engineers would

^

60

AMERICAN SEWERAGE PRACTICE

select had they been free from the necasaity of fitting the new work
into the old.

The valuation of the brick and pipe newen? was conducted by different
methods. In the oase of brick sewers, competent inspectors made a
personal investigation of the interior of about 60 aewers, having a total
length of about 20 miles. These were divided into four claasee, the first
including sewers built before 1845, the second those constructed between
1845 and ISoo, the third sewers built between 1855 and 1872, and the
fourth those constructed between 1872 and 1883* Mr. HufeLand waa
con\'inc«d from close knowledge of the construction and condition of the
sewenj built after 1883, that it was safe to assume these had not materially
deteriorated from their original value. There were a few sewers in this
class to which this generalization did not apply > and thase were valued
independently under known conditions. This opinion of the value of
these later sewers was based to a large extent on changes in methods of
construotion adopted after 1883.

The examination showed that the brick aewers deteriorated in a series
of progressive steps. The first sign of service occurred when the cement
was found to be partly out of the joint at the water line» a deterioration
of about 2 per cent., aocording to the scale which was adopted after
prolonged study. The next ty]>e of deterioration waa the partial absence
of cement above the water fine, which was rat-ed as a 6 per c^nt, injury.
Next came a deprassion of the arch and a sUght sj>reading of the aewer,
which waii considered a 12 per cent* deterioration; then came, in turn,
the appearance of large open joints, rated at 25 per cent.; the existence
of loose brick, rated at 47 per cent.; a breiiking of the bond of the brick-
work, rated at 72 per cent., and finally a distortion of the aides and
bott43m» with the joints becoming out of line, which was considered com-
plete wreckage of the sewer for serviceable purj>osc. It was assumed
that when the bond of the brickwork beciune broken, equivalent to a
deterioration percentage of 72 on the t^cale, the sewer wa.s so far gone that
it was not economical to attempt to repair it. The condition of the sewer
was stated by adding together the percentages of deterioration correspond-
ing to the defects that were observed If all of the defects up to and in-
cluding the presence of loose brick were observed, then the total of the
faults would bo 2 -h 6 4- 12 + 25 -f 47 = 92. This sewer would still
be worth repairing, but if the bond of thi* brickwork was found broken, a
72 per cent, deterioration, the total depreciate<l value would become 164,
when the sewer was considered valueless. Twenty sf?wcrs built before
1K49 were oxnmined, and nearly every one showccl a degree of detcriorur
lion exceeding 164, for which reason it was docideil that a brick sewer
in Manhat tan had a ui?cf ul Ufe of not over t>4 years on the average. Bewew
built by the methods adopted toward the close of 1883 and subsequently

GSSBRAL ARRANGEMENT OF SEWERAGE SYSTEMS

(U

have a longer life, of course, a fact which stiould not be overlooked
1 wiy nm made of Mr, Hufeland^s report.
The first pipe sowers were hud in Manhattan about 1865. and until
87 tbey were laid on the earth at the bottom of the trench without any
lit ion. It required but a shght leak from a joint to wa.ih away the
i enough to permit one end of the pipe to drop m as to caune a nerious
iurba.ncc of the line. In 1887 the concrete cradle now used in Man-
was ixitrcKluced, which resulted in a great improvement in the
on of the pipe sewers in service. Another tendency of the pipe
WOB to break at and above the center, due iK'.rha|)4i to the load
npoMod on the top or even to some form of disintegration due to thia
t, according to Mr. Hufeland. The pipe used in Manhattan were
and 18 in. in diameter, and the breaks occurred so much more
otiy in the largcj^t size that its use was discontinued in 1887.
ere were fewer breaks in the lo-in, pipe and still fewer in the l2-in.
pipe lines were examined rather unBatisfactorily by means of
nsBiecied lights and calipers, pushed througli the pipes by rods. Some
iftfornmUon was obtained from the experience of the engineers and
workmen engaged in repairing pipe sewers and inserting spurs for house
oaiLtiei*4ioQ9; some of the workmen in charge of this labor hiui been en-
glifHl un it for 25 yeai>5 and were of much lielp in reaching what wa^
btliered to bo a fair aj>proximation to the present \^alue of the pipe.
Vr nation obtained in this way, and a knowle<ige of the

t>: , curves were oonstructed showing the approximate

t of deterioration of thesewers with their age. One cun'e answered
8, but it was considered advisable to use tliree for pipe
to the great difference in the rate of their deterioration
. Tliesc curves are reproduced in Engineering Ncivs, !>ut
are n-- -,.. ,-i here because they are based on local conditions and poor
ooQ^truction, as already mentioned. In fact, Mr, Hufeland's report
npeiywbere IndkateH abelief on hi« part that an investigation of the actual
aoaifitiogi of aa maoy sewers m possible should be made before any
alteoipt is made to uae this method in appraising the value of a sewerage

I Ib this eaao the results showed that the 2,551,275 ft. of sewers, with
I nally $22,956,451, and had a value onDeq.
123. There were ^,172 catch basins on the
wliich wore e«timated to have a present value of $685 ,798 »
' "■ — 'd cost of $923 ,875, This givej* a total cost of the system of
f23,> ud a present value of $18,G64,92l. This sy8t<5m includes

brick #t»wcn> of 125 dif /es, 17 sizes of pipe suwers, 23 sixei^ of

vnad sewera, about 25 ^ uf catch bt\sins» and *'nll kin<is <ff man-

bidat.^ Ttic apj4rais:il work lasted over a period of 10 months and cost

CHAPTER 11

HYDRAULICS OF SEWERS

The science of hydrodynamics is that branch of hydraulir.^ which
treats of the mechanics of fluids in motion. The sicienc© of hydri^
statics, on the other hand, treats of the mechanics of fluids at rest.

Tho term hydraulics is hero used as having the broader significance
including both hydrostatics and hydrodynamics. This chapter, there-
fore, embraces a brief reference to water and some of its mor^ im-
portant physical attributes, and to certain of the principles of
hydrostatics, and a more extended difcicussion of hydrodynamics ot
the principles governing flow, more particularly in sewers.

As sewage is composed of 99.8 per cent, of water and but 0.2 per
cent, of mineral and organic matter, and has a specific gravity but
very little in excess of unity (1.002 approximately), it is treate«i in hy-
draulic discussions as if it were cle^r water. The retarding effects of
its contents at times and untler certain conditions, and more particularly
at the dead ends of the collecting system, are not to bo lo«t sight of»
however.

WATER

Water (HsO) is a colorless liquid with high solvent powers. Havi
great fluidity, or little viscosity, it transmits pressures equally in all
directions throughout its mass, the direction of the pressure being normal
to the surface to which it is applied (Pascal's law).

Water may be asaumed to be substantially incompressible in hy-
draulic computations, its coeflficient of con ' ility, or <i In
unit volume, caused by a pressure of one atn . ( 14.7 lb. i n?
inch), being approximately 0.0(KH)5. Its modulus* of elasticity, E, in
compression is approximately 290,000 lb. per square inch. The modulus
increases and the coeflii^ient of compressibihty decreases slightly with
increase in temperature. As an increase in pressure of 10 a^' •*
increases the weight of water cmly by about OAYA lb. per culn no
eflfect of compressihihtj'^ is negligible*

Molecular Changes. — Water reaches ile- uu^AUMiun density at 39.3°
F*, at which point its specific gravity is unity. Water frcexc^ at 32*

62

I

BiMBi

nrDRAUucs of sswer^-

63

F.. vbeii it0 spodfie gravity k QJ999S7* If it is absolutely quiescent,
bo««viir,' the tao^ien^liire uiJiy fall to 20® F. or lees before freettng takes
pbm, aod tf oo the otber faund it is fiowtng rapidly^ a:3 in a strennir it
will ftlao ttJX m teonperalitre conmderabi>' below 32° F, b^ore freexing.
lot mdta, boworer, at 32^ F. or 0° C. It is owing to the fact that the
Mp%giffififn density of water occurs at a slightly higher temperature
Ihan tbe (reeupg point that Ixxlies of fresh waiter do not freexe to a
greater depth* for as the temperature of the w^ater gradually falls in the
^ early wtsit«r» the point of maximum density is reached at Z9.Z^ F., and
I water chills further at the surface, by reason of its contact with
atmo^here. it^ specific gravity h raised and the cold layer
f water therefore 0oats» except as wind currents may cause circulation
rarr>' some of it to Iowxt depths^ and thus continues to fall in
t^mprrature until the ice sheet forms.
Water boib at sea level (barometric pressure of 30 in. of mercury, or
ft- nf water) at 212^ ¥., when its specific gravity is approxiinati'Iy
IL9SS55.

i Welgjit of Water*— Fresh water weighs about 62,43 lb. per cubic
ot For approximate computationis, the unit 62,5 lb, is often used
- tta eoDvenieiice, as then

1000
1 cu. ft. -62.5 lb.= ,^ lb.* 1000 oa.

10

Sail water vaHeet in density and weight, that of the Atlantic Ocean
wvil^ngi in the latitude of New^ York, approximately 64 J lb., in the
Gulf of Mf'vico, 03,9. The water in Great Salt Lake weighs from 69
~ I 76 III. fcKit.

Ice wcK - ^ to 57.5 lb. per cubic foot,

[ Sewafl:^ b umjally assumed to have the same weight as water* In an
Ml ■' by Harrison P, Eddy of the weight of the sewage

_ii the North Metropolitan 8ewer at East Boston, a
fe imvity of 1.0018 was found, the sewage having 1022 part^ of
per imUion. Tlua would correspond to an excess of 0.1 lb,
toliic ftJot, over tlio w*eiftht of fresh wateri and this was a fairly
I Ainerican j<cnva(^t\ contaiiunK mu<'h wait or sea water.
AtDloefihefic Pressure at sea level will su^stain a column of
30 in, liigh, in vacutuu, and of water, 34 ft. As mercury
wdgtiji 0,49 lb. per cubie inch this corresponds to 30x0.49-14.70 lb.
per «t|uare inch prcssuro ( 1 .033 kg. per square centimeter). This is
kaifwu a- of one atmosphere, the pressurt^ of twcv atmos-

lb* MIS amount, or approximately 29,4 lb. per square

eh.

64

AMERICAN SEWERAGE PRACTICE

Table 5. — Atmospheric Pressures and Equivalentb

(Merriman's "Treatise on Hydraulics, 1912," p. 8)

Mercury

barometer,

inches

Pressure
pounds per
square inch

Pressure
atmospheres

Water

barometer,

feet

Elevations,
feet

Boilinc point

of water,
Fahrenheit

31

15.2

1.03

35.1

-890

213. 9*»

30

14.7

1.00

34.0

0

212.2

29

14.2

0.97

32.9.

+920

210.4

28

13.7

0.93

31.7

1.880

208.7

27

13.2

0.90

30.6

2,870

206.9

26

12.7

0.86

29.6

3.900

205.0

25

12.2

0.83

28.3

4,970

203.1

24

11.7

0.80

27.2

6,080

201.1

23

11.3

0.76

26.1

7.240

199.0

22

10.8

0.72

24.9

8.455

196.9

21

10.3

0.69

23.8

9,720

194.7

20

9.8

0.67

22.7

11.050

192.4

The Acceleration due to Oraviiy is approximately 32.16 ft. per second
at sea level. Hcring gives in his ''Conversion Tables'' the following
values at sea level and 45^ latitude for the linear acceleration due to

Logariihm,

Gravity =980.5966 cm. per sec. (Aprx. 1000) 2.9914904

= 35.3015 km. per hr. per sec. (or per sec. per hr.)

(Aprx. 1x10) 1.5477929

= 32. 1717 ft. per sec. per sec. (Aprx. 32) 1 . 5074746

= 21 . 9353 miles per hr. per sec. (or per sec. per hr.)

(Aprx. 22.) 1.3411433

= 9 . 805966 meters per sec. per sec. (Aprx. 10) 0. 9914904

Table 6. — Functions of Acceleration Due to Gravity, g

(Hughes & SafTord's "Hydraulics," p. 8)

In feet

In me
Number

ters

Number | Log

Log

g

2(/--

(2j?)«

I(2(/)»

1

32.16 , 1.5073
64.32 1.8083 ;
8.02 0.9042
5.347 0.7281

0.01555 2.1917 1

9.803

19.607

4.428

2.952

0.051

0.9914
1.2924
0.6462
0.4701

2.7076

2|^

Merriman credits Pierce with the following partly theoretical, partly
empirical formula for the determination of the acceleration of gravity,
g, in feet-per-second per second, for a latitude, Z, and an elevation, f,
in feet above the sea level.

^ = 32.0894 (1+0.0052375 sin« /) (1-0.00000009576)

HYDRAULICS OF SEWERS

65

Intensity of Water Pressure. — Ignoring the influence of changes in
atmospheric conditions and extern&l forces, the intensity of pressure
on the unit of area, resulting from a colunm of fluid of given height,
is equal to the weight of the fluid, per unit volume, times its height.

P« pounds per square foot, =62.4A
p» pounds per square inch, = 0.4333A

w
A»0.016P in pounds per square foot
h a2.308p in pounds per square inch

where u^s weight of water per cubic foot and A = head or height of
column of water, in feet.

Expressed in words, this means that a pressure of 1 lb. per square
inch corresponds to a head of 2.308 ft. of water. A pressure of 1 kg.
per square centimeter corresponds to a head of 10 m.

A head of 1 ft. of water produces a pressiu-e of 0.433 lb. per square
inch. A head of 1 m. produces a pressure of 0.1 kg. per square
centimeter.

Table 7. — Conversion Factors for Unpts of Pressure

(Hughes A Safford's " Hydraulics," p. 6)

Fe«t of
water

i Inches
Log 1 of mer-
■\ cury

!

1

Log :

i

Pounds

per
square

inch

Log

■

Pounds

per
square

foot

Log

Pounds per square

1

'

•

iaeh to

2.308

0.3632 i 2.037 0.3090

'1 L 1

1.0000 0.00001

1. 1

144.00

2.1584

Pounds per square

fool to

0.01603

2.2048 1 0.01414 2.1506

0.00694 3.84 16i

l.OOOO.OOOOl

Inches in height of

1

1

1 1

mercury to

1.133

0.0542, 1.000

0.0000

0.4910 ,1.6910

70.699 1.8494 1

Feet in height of

,1

1

1

1

1 ■ i

fresh water to. . .

1.000

0.0000 ' 0.8826

1.9458

0.4333 ,1.6368

62.4

1.7952

Feet in height of

ll

1

!. i

sea water to

1.025

0.0107 1 0.9047

1.9566

0.4442 ' 1.64751

64.0

1.8062

Atmospheres to . . . 33 . 023

1.5305 29.942

1.4763 1 14. 70 ' 1.1673,

2116.8

3.3257

Sea

1

' i

Atmospheres to. . . water

• 1

,1 1

1 3:r()96

,1

8peri6c gravities used in this table are: distilled water, 1.000; sea water, 1.025; mercury
13.5956.

For rough calculations the weight of fresh water is frequently taken as 62.5 lb. per cubic
foot: and one atmosphere e<iuivalent to 34 ft. of fresh water, 33 ft. of sea water, or 30 in. of

THE FLOW OF WATER

The laws of hydraulics are essentially similar to the fundamental
laws of mechanics. The basic principles governing the flow of water,
5

66

AMERICAN SEWERAGE PRACTICE

neglecting the disturbing or modifying influences of friction and initial
pressure, are founded upon the laws of falling bodies.

In 1643 Torricelli enunciated the theorem that, ''the velocity of a fluid
passing through an orifice in the aide of a reservoir i« the same as that which
18 acquired by a body falling freely in vacuo from a vertical height measureil
from the surface of the fluid in the re^rvoir to the center of the orifice.'*
(Hughes and Saft'ord's "Hydraulics.** page S).

In 1738 Dafticl Bernoulli, the eminent mathematician of Baale, Switjser-
land, propounded the important hydraulic law of the conservation of energy
in fluids^ which may be stated thus: " At every section of a continuous and
steady stream of frictionless fluids the total energy is constant; whatever
energ>' is lost as pressure is gained as velocity. Therefore, in terms of head:
Total energy = velocity head -{-pressure head -|- head due to position ~ con-
stant." (Hughes aad Safford'a '* Hydraulics," page 81.)

Laws of Falling Bodies. — Neglecting the influence of friction, th
laws of falling bodies are as follows:

If 1^ = velocity in feet per second at any moment,
< = time in seconds^

h = fall or vertical distance traveled, in feet,
if = acceleration of gravity (32.16 approximately).

V = gt = 32 Aa (1

or, in words, the velocity of a falling body in a vacuum at any momeij
is equal to the time of the fall multiplied by the acceleration of gravit

t^igt'

32.16

^*- 16.08/'

or, the distance traversed, or the fall in feet, is equal to one^half of the
product of the acceleration of gravity times the square of the time, in
seconds, elapsing in the falL

= 0.01555t'^

*"'2g~' 64732'

or the distance traversed, or the fail in feet, of the velocity head,
equal to the square of the velocity divided by two times the accelerntiQ
of gravity.

r = V^=8.02\/A (4

or the velocity is equal to the square root of two times the fall in fe
multiplied by the acceleration of gra^^ty. The velot^ity then vari|
as the time and as the square root of the head, and the head variea i
the square of the time and the square of the velocity.
If there be an initial velocity, r, in feet per second,

£k)uation (1) becomes f?« T+gt

Equation (2) hecomcH h = jj/P^fc Vt

Kqujtiion (4) lj*M'<>nio.s t'=V2^A^V*

^M

^^^1

■

^M

■

■

^M

^^^H

pm^i^^^^^i

HY

H

DRAULICS OF SEWERS C7 ^H

r Tablc d — Tdeorbticai. Velocity of Water in Feet per Second ^^|

^k

TOR Various Heads ^^|

^m

y''\/2ah, ff -32.16 (V. S. RedmraAtion 8<?Tvic«>

.^H

m

lt««4 In f*<^t

0 0 1 O.l

0.2

0.3

0.4 1 0.5 1 0.6

0,7

0,8

0,0 '

■

0

DO

2,fi

3.6

4 4

5.1

5.7

6.2

6.7

7.2

7.6

I

« 0

8.4

8.8

0 I

0 5

0.8

10.1

10.5

10.8

11. 1

^^H

2

ira

11.6

U.O

12 2

13.4

12.7

12.0

13.2

13.4

13 7

^^H

3

is.y

14.1

14 3

14,6

14.8

16.0

15.2

15 4

15 6

15 8

^^K

4

If. 0

1ft. 2

16.4

16.0

16 8

17.0

17.2

17.4

17.6

17.8

^H

6

no

16. 1

18.3

18.5

18.6

18.8

10.0

10.2

10.3

10.5

^H

0

ifl «

19,8

20.0

20.1

20 3

20.5

20.8

20,8

20.0

21.1

^^H

7

21.2

21.4

21 5

21.7

21 8

22 0

22.1

22.3

23.4

22.5

^^1

H

22 7

22.8

23.0

23.1

23.3

33.4

23.5

23.7

23.8

23,0

^^^H

0

^.1

24.2

24.3

24.5

34 0

24.7

24.8

35.0

25.1

25.2

^H

10

2S.4

35.5

25 6

25.7

25.0

2«.0

36.1

26.2

26.4

26.5

^^H

a

20.0

26.7

26,8

27 0

27. r

27.2

27.3

27.4

27.5

27 7

^^H

* 12

57. »

27.0

28.0

28-1

28 2

28.4

28 5

28 6

28.7

28.8

^^1

1^

28.9

20.0

20 1

29 2

20.1

20 5

29.0

20.7

20.8

20. g

^^K

^m

14

30.0

30.1

30.2

30.3

30.4

30.6

30.6

30.7

30.0

31,0

^H

m »

ail

81,2

31.8

31-4

31 5

31.6

31.7

31.8

31.0

32.0

^1

^ 16

33.1

.12.2

32 3

32.4

32.6

32.0

32.7

32.8

32.0

33,0

^^^1

IT

33 1

33.2

3a 3

33 4 1 33,5

33.5

33.6

33 7

33.8

33 0

^^1

1«

34 n

»4.1

34.2

34.3

34.4

34 5

34.6

34.7 1

34.8

.14 *> 1

^^1

■

tn

36.0

35.0

35.1

35.2

35.3

36.4

35.6

36.6

86.7

35 . H

^1

m

3»

35 0

3rt 0

36.0

36.1

36.2

36.3

36.4

36.5

36.fi

?6 7

^H

■

21

30.8

36.8

36.9

37,0

37.1

37 2

37.3

87,4

37.4

37.5

^^1

f2

37. ft

37.7

37.8

37.0

38.0

38.0

38.1

38.2

38.3

38 4

^^^1

3;i

:m a

38 5

38.6

38 7

38,8

38.9

30.0

39 0 1

30.1

30 2

^^K

W

do.a

30,4

30.5

39.5

30.0

30.7

30.8

30.0

30.0

40,0

^H

^

Ifl

40.1

40.3

40.3

10,3

40.4

40.5

40.6

40.7

40.7

40.8

^H

^Hi

Sll

40.0

4KQ

41 1

41.1

41.2

41.3

41.4

41.4

41,5

41 6

^^1

^^H

17

41 7

41. 8

41.8

41.0

42.0

42.1

42.1

42.2

42.3

42.4

^^1

^^H

28

«2.4

42.5

42.6

42.7

42.7

42.8

42.0

43.0

43.1

43 2

^^H

■

i4>

43.2

43. a

43 8

43,4

43.5

43.6

43.6

43 7

43.8

43.0

^1

ai9

13.0

44.0

44.1

44.2

44.2

44.3

44.4

44 4

44.5

44.6

^^1

St

44.7

44 7

44.8

44.0

44.0

45.0

45.1

45.2

45.2

45 3

^^1

s

45*4

45.4

45.5

45.6

45.0

45.7

45.8

45.0

45.0

46 0

^^H

J3

46.1

48/1

46.2

46.3

46.3

40.4

46.5

46.6

46.6

46 7

.^^H

«i

4AK

46.8

46.9

47.0

47,0

47.1

47.3 1

47.2

47.3

47.4

^H

,.^.

»

47 4

47 5

47.6

47.6

«,7

47.8

47.0

47.0

48.0

48,1

^H

^^K

Jl

4a 1

48 3

483

48 3

48.4

48.6

48.5 1

48.6

48.6

48.7

^^H

^^^K

S_ ^

4» J«

48,8

48.0

40 0

40 1

40,1

40.3

40.3

40.3

40.4

^^H

^^H

■ **

40 4

40.5

40.6

4t> 6

40.7

40,8

40.8

40 0

50,0

50.0

^^H

■

■ ^

m.i

50 1

50.3

50 3

50.3

60.4

50.5

50 5

50.6

50.7

^1

■

■ l.

m.7

60.8

50.6

50.0

51 0

51.0

51.1

51.2

51.2

51.3

^1

r 41

&\ 4

61.4

51 5

51 5

61 6

51.7

51.7

51.8

51.0

51,0

^^1

11

42.0

63.0

53.1

52.3

63.2

53.3

63.8

52.4

53.6

52 5

^^1

«

62 A

62.7

62.7

52.8

52.8

52.0

63.0

53.0

63.1

53.1

^^H

4«

ft3 2

69.8

53.3

5.1 4

53,4

53.5

63,6

53.6

68.7

63 T

^1

(...

&.t A

68.0

53.0

54 0 54.0

64.1 64.2

54.3

64.3

54 3

^1

tl)

Jk 4

54. 5

54 5

54 6

54.6

64.7 64 7

54.8

64.0

54.0

^^1

17

A5 n

55 0

55 t

55 2

55.2

65 3 55 3

55 4

55,5

55 5

^^1

•«

«4 R

55.6

55 7

55 7

55 8 55,0 55.0

56 0

56 f>

5n I

^^1

^^

ii

All 1 &CV 2

.VI :<

66.3

66.4 56 4 56 5

56.6

56 tt

56.7

^^^

1

^^

68

AMERICAN SEWERAGE PRACTICE

FLOW OF WATER THROUGH PIPES

Water seeks its own level, the level or surface being approxima
perpendicular to the direction of the force of gravity. Conversely^
its surface be not level, it wiU flow from the higher level to the lower.
This is but another way of sajdug that difference in pressure, or in lcv(
or **head/' as it ia called technicallv is necessary to make water flow-i
a fact aometinias overlooked.

If, then, there be available a certain difference in level — called "fall
if measured from the upper point to the lower, or **head" if measur
from the lower to the upper — between two points along a pipe, conduil
or channel carrying water or any other liquid, flow will be induced at
a rate dependent^ firsts upon the fall aa compared with the lenRth
traversed; Bocond, upon the croas-section of the pipe, conduit, or channel;
third, upon the character of its interior surface; fourth, upon the
condition of flow with reference to the pipe, i.e., whether the pipe is
under pressure or not, whether it is flowing full or partly full, and
whether it is flowitig uniformly, steadily, variably, or intermittently
on account of constant or variable cross-section, or other cause; an^
fifth, upon the character, specific gravity and mcosity of the liqui^

Let us examine briefly the hydraulic conditions of flow, first, in pip
flowing full or under pressure, i.e., in pipes in which the pressure is oa|
ward, as in water pipes, and second, in pipo.^ or conduits flowing bare
full or partly full in which there is no outward pressure of the liquid i
all directions, or in which the pressure may be said to be Inward, as i
tlie case of sewer pipes.

Bernoulli's theorem, that the total energy*' in a steady stream of fiii
tionlcss fluid is a constant and is equal to the elevation plus the velocity
head plus the pressure head, may be expressed by the following fomiu

H = h. + h.+h. = h.+lV~>

where /f = total head,

/^^tbe height of any point above any assumed pUno of refer*

ence, the reference plane,
A* = velocity head,
A»— pressure head,
J? = pressure in pounds per »mil area,
w — weight of water per unit volume*
08 velocity of flowing particles, in unit of dbtance, per socoii

Practicfdly the conditions of the perfect fluid du not exist, aij
another element enters the problem, the frictional resistance of the pip
channel, or coiuiuit to tlie flowing fluid. This factor to eovenKi
Bernoulli's theorem by the addition of another tami in the equal

HYDRAULICS OF SEWERS

68

I ^ven. As applied to two dlffcirent points, A and B, upon the pipe-
He:

iinH the same nomenclature and / being the loss in head due to the
nctiooal resistance of the surface traversed by the fluid in parsing from
It S to point B.

Th« more important elements of frietional loss in pipes are the frio-
loas duo to the interior nurface of the pipe, tlie lo^ on entrance
ato thopipe, called the " entry head, " losses due to sudden enlargementi
\ due to sudden contraction, losses duo to bonds, losses due to gates,
ttc. In sewer construction, the loss due to the friction upon the in-
rior erf the pipe surface is practically the only one which has gonorally

(lo I" * 1 rt?cL

Tfr ii i^iid loss 19 approximately equal to 0,505 time^the velocity

or ii.5v^/2g, whore the pipe enters from a manhole or reservoir
ae tfort. If the entry is made through a bell mouth, however,
this Ioe» may bo reduced to less than 0.1 times the veltjcity head*

T! le t« sudden enlargement is equal to the square of the dif-

fercf ,r velocitie.s in the two sections divided by 2g, or {v — Vi)^-h2g,

tiio enlargement is made gradual by a tapering connection, the
due to enlargement may be reduced to a negligible quantity,
ftnaximum diBciiarge from a divergent mouthpiece is derived when
f angh^ made by the sides of the mouthpiece is approximately 13** 24'.
A. P, Folweli, in an interesting article on *'Lost Head in Water Supply
y^tmui*" {Eng. Ncnmf Apr, 17, 1902) recommends m sufficiently ae-
Bt practical purposes, the following approxinmte allowances
i above that in an equal length of straight pipe:
In open valve, loss equal to (hat in 5 ft. of straight pipe, in excess of loss
I in equaJ lc?ngth of dtraight pipe.
In hmU vUmpni valve, 80 ft. cJitto.
lo orditiar>* cjiat iron 90" benda, 10 ft. ditto.
la ardirmr>' in\ 3 ft.
la ordinary cr<j»**», 10 ft.

WiUinm O. WehUr repc»rted in Eng. Newn, Jan. 10. 1D07, page 38,
[ ttit llie obittrucUons due to valves and fittings, expressed in the number
rf fi^t ol clean, straight pipe of the same size which would cause the
UmA iwi the fitting, were found by experiment to be as follows:
^^ l*nitt and Cady check valve, 50; (Win. VV^al worth globe check
nl?^, 200; 4-jn. Pratt and Cady check valve, 25; 4-in. Walworth globe
(Wk valve, 130; 2i toS-tn, long-turn ells, 4; 2J to 8-in. short-turn ella,
I S-iiL long-turn tees, 9; 3 to 8-in. short-turn tecs, 17; one-eighth

Sc Grade Line,— The hydraulic grade line represents tho
"' '•ti plane of reference to which water would rise

70

AMERICAN SEWERAGE PRACTICE

at various points along any pipe-line or conduit, discharg;ing undi
pressure, were piezometer tubes, or vertical pipes open to the atmi
phere. inserted in the pipe-line. It is a measure of the pressure hea^
available at these points. The hydraulic grade line will, of course,
bo infiucnecHl not only l>y the elevation of the points under question
and the frictional re^intanre due to the rugos^ity of the internal pipe
surface, but also by anything influencing the velocity head* In the
ease of a canal or open channel, in contradistinction to tlje pipe undi
pressure, the hydraulic grade Une corresponds with the profile of i*
water surface.

Steady flow exists in a pipe-line, canal, or stream when equal quan-
tities of water pass the same point in like intervals of time, or, in other
words, when the discharge is constant for successive intervals of time.

Uniform flow exists when the cross-section and the mean velocity
of the flowing stream are the same at every point. Uniform flow is
a steady flow in wliich the cross-sections of the stream are all alike, and
its surface is parallel to its bed*

The difference in these two conditions of flow must bo clearly home
in mind on account of its bearing upon loss of head due to various
causes. It is illustrated by the comparison in flow through a pipe line
of uniform diameter throughout its length and through a Venturi
meter the ends of which are of similar diameter. WliOe both may be
discharging the same quantity of water, the flow in the former is uni-
form, in the latter, steady, due to its varying cross-section.

Critical Velocity. — Hughes and Safford state (Hydraulics, pp. 90-92)
"Turbulent eddying motion exista in nearly all cases in practical hydrauhc
probleme, and the resistance to flow varies in proportion to some power of_
the mean velocity between 1,7 and 2,0 or more. Certain invcstigaiiai]
however, have shown that at very low velocitiea the motion of the water 1
in paralk'l stream Lines, that is, without the disturbance due to eddying
motion; and the resistance to flow varies nearly directly as the mean veloci^
of flow. The velocity at which turbulent eddying motion begins or ce
ia called the critical velocity.

*' Reynolds^ made experiments to determine the point of critical vetooll
and fotmd that there were two critic?d values for any pipe or tube; *Qtimi
which sternly motion changed into cddien. the other at which eddies chi
into f^teady motion.* The former change was found to occur at velocit
consiticrably higher than the latter; and the two critical points are, the
fore. cM&i\ 'the higher critical velocity' and 'the lower critical velocity/ ^

**Far the higher critical velocity,

iff-^^rt^ r^ (meters per second) » or

F
v^ =0,2458^ (feet per aecon*

^Othom* RtyntAdt, PhU. Tr&ti*. at %km Hay. riot* , 1Sk:i, pp. sr.W nt mq.

m

HYDRAULICS OF SEWERS

71

D » the diameter of the pipe in meters, or feet,

p« (1 4.0.03a(>r -f 0.000221 n)'* is the temperature correction,

T - tetuperttture of the water, degrees Centigrade.

For the lower critical velocity,

IP P

'**278 D (™®^^®^J ^^ *^c =0.0387 ^ (feet).

^Esfperiments by Barnes and Coker* show values for the higher critical

city fully double those of Reynolds, and for the lower critical velocity

tiler r4^ half a^i much as Reynolds,

"All thowj exficriinenta showeil that disturbances in the supply tank, or

I Jmring of Ute pipes, made a marked change in the point of critical velocity.

1 ¥m pnictical (Conditions the point of critical velocity cannot be very precisely

detenmued ; and except for small pipes is usually too low to be considered.

(WiUiams, Hubbell and Fenkell's discission on "Flow of Water in
I Pipes.** Trans. Am. Soc. C. E., April, 1902, p. 307),

• • * ♦ The experiments of Poiseuille, Hagen^ Jacobaon and
iiaxen show that when water flows through capillary tubes or fine sands
JRilBre it is prevented from taking up internal motions, because the area of
tbii cros^section of the stream is almost molecular, that /// varies very
imarSy as the first power of V. All reliable experimenta on record show that
M tb« diameter decreases the exponent of F, in /// = mF*, decreases, as
bui been shown for the lines investigated in this paper: 30 in., i//-mV*';
Win., //> =ffil^»'"*; 12 in., H/^mV^^^; and 2 in. brass, F^-mFi", from a
^KMuble limit of F*. J n other words, the more the chance for internal resist^
the higher the ex|>on(mt of V. To the writers, then, the variation of
escponcnt of V is an index of the character of the flow, and when that
greater than unity. straiKht-line flow is over, or, the critical velocity
Reynolds is past. If, then, the**e internal motions are capalilQ
r^^ the rate of loss of head, it is evident that in them the con-
- of the lavvs of flow are to be looked for, rather than in the
H, But, beyond this first critical velocity, there appear
to be atben» where peculiar phenomena appear, ♦ ♦ • ♦ •."

The reaintance to flow for velocitiea under the critical velocity [the
I pmtA mt which eildying begins and ends?! for capillary* tubes and small
^ pipes may be approximately computed by tho following formula sug-
I by Allen Haasen:'

r«cs/>;

i^«*the alope of tho hydraulic grade line^
Faethe mean velocity of flow in feet per second,
D, - the diameter in inches,

r Xhm Roy Soe . Vf>l. 74. pp. 341-35ft.

n. Tr»M. Am. 0oo. C. E.. Vol. 61. pp* St(i-ai9.

<jf r
a-

trr^l'

72

AMERICAN SEWERAGE PRACTICE

i = the temperature of the water, degrees Fahrenheit,
c~ii factor; from Baph and Schoder'a experiments ori bras
pipes Hazen determined c to be from 462 to 584 ; VVilliaixiJ
and Hazen use a value of 475 in their ** Hydraulic Tables,'*

I

I

DISCHARGE OF PIPES

Equation of Continuity, — The discharge of any pipe-line is given
the oxprosiiiyn, Q==A]\ in which

Q = the discharge in cubic feet per second,

A = the area of cross-section of the flowing stream

in square feet,
r = velocity in feet per second, or other units

time and apace.

If the flow is continuous in any given pipe-hne there follows tb
equation of continuity,

AV^av J

using the same nomenclature, the large letters referring to the aretf
and the velocity of the flowing stream at one cross-section of the pipe-
line, and the small letters to the area and velocity at another point.

In the above cases by the term ** velocity*' is meant the mean
average velocity in the entire cross-section. Where the term veloci
iti feet per soeoud or in some other units of time and space,
been used, the mean vcloc^ity in the cross-section of the flowing strea]
has been referred to, for it is clear that with frictional resistance on the
walls of the pipe or conduit, the velocity of flow at the point of contact
of tlio fluid with tliese walls must be less than that in the center of tiie
stream* The variation in the velocity at different points in the cr^
section of any pipe discharging under pressure is shown in an appro;
mate maimer in Figs, 12, 13 and 19.

Mean velocity is dependent upon, first, the available head or fal
second, the resistance to the flowing stream*

The resistance in it^ turn varies with the length, wetted periniel
and cross-section of the pipe, conduit or chatmel; the rugasity» or rouj
ness, of its interior surface; the temperature and hence viscosity of
fluid: and the condition of flow, uniform, steady or variable. The
sistance was shown by Dubuat to be independent of the water fin
thu:^ cstijilbhing the essential dtfl'ert'nre between the fricti^ r nn

of a fluid and a solid as <onj pared with the frictional rt>i .f t

eaUds — tlie latter of which is dependent upon the weight or preeBtir« of
on© solid upon I lie other.

Development of Formulas for Flow in Pipes and Channels. — Gm^a*
guillct and Kuti4T ( and Olhor Chauoels,

trauslati'd bv nirltiL^

ntjM

the

act

tiie

osaH
oxfl

falfl

74

AMERICAN SEWERAGE PRACTICE

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76 AMERICAN SEWERAGE PRACTICE

"The first attempt to discover the law by which the velocity of water
depends upon the fall and the' cross-section of the channel was, according
to Hagen, made by Brahms (1753), who observed that the acceleration which
we should expect in accordance with the law of gravity does not take place
in streams, but that the water in them acquires a constant velocity. He
points to the friction of the water against the wet perimeter as the force
which opposes the acceleration, and assumes that its resistance is propor-
tional to the mean radius i2, i.e., to the area of cross-section divided by the
wet perimeter.

Brahms and Chezy (1775) are to be regarded as the authors of the well-
known formula

in which p=» velocity in feet per second,
c — coefficient of roughness,
a = area of cross-section in square feet,
p = wetted perimeter in feet,
/i -head or fall in feet,
I = length in feet,

i? = hydraulic mean radius = >

P
S = slope.

The principle established by Michelotti and Bossut, that the laws
governing the flow of water must bo established experimentally, led
Dubuat (1779) to investigate the flow of the Canal du Jard and th©
River Heine in France, and of experimental channels. He concluded
that the force producing flow was the fall or slope of the water surface
of the flowing stream, and that the resistance must be equal to thi^
accelerating force, under conditions of uniform flow.

Do Prony concluded (Ganguillet and Kuttcr^s "Flow of Water ix^
Rivers and Other Channels," pj). 4 and o).

**Thc particles of water in a vertical line in the rross-seotion of a streaiO
move with different velocities, which diminish from the surface to th^
bottom.

The surface, bottom, and mean velocities stand in a certain relation tc^
each other, which Diihuat, strange to say, finds to be independent of th^
size and form of the cross-section.

A layer of water adheres to the walls of the pijio or channel, and is there^
fore to he regarded as the wall i)r()per which surrounds the flowing mass.
According to Duhuat's experiments the adhesive attraction of the walld
seems to cease at this layer, so that differences in the material of the walls
pnxlucc no p(^rcej)tihle change in the resistance.

The particles of water attract each other mutually, and are themselves
attracted by the walls of the channel. These attractions (resistances) may,
in general, ho expres.sed by means of two ditTerent values, which, however,
are supposed to be the same nature and comparable with each other."

HYDRAULICS OF SEWERS

77

Later, H. Darcy, Inspector General of Roads and Bridges, noted
that the pipes having the smoothest interior surface delivered the
greatest quantity of water and thus indicated the least frictional resist-
ance to the flow. Believing that similar conditions must prevail in
flowing streams, he began a series of experiments, continued after his
death by his assistant, the famous hydraulic engineer, H. Bazin. These
experiments, which covered observations not alone upon canals and
rivers but also upon artificial channels, led to the well-known Bazin
formula for the flow of water in pipes.

Bazin's Old Fonnula for the flow of water is, in its general form, as
follows:

RS=(a + ^v\

or

RS

; = ^a+^-

T^/RS

«+

R

The coeflicients a and /9 were determined, graphically, from the plotted
results of experimental measurements. Bazin grouped his channels
under four classifications, for which he determined the values of a
and^ in Table 9 and to this classification a fifth was added in like
maoncr by Ganguillet and Kutter, at a later date:

Table 9. — Constants for use in Bazin's (Old) Formula

Cftiegory

Channclfl

III
IV
V

Cemnnt 1

Carefully planed woo<l /

Smooth aahlar j

Brick \

Unplaned wood J

Rubble masonry

Earth

Carrying detritus and coarse
gravel.

for EnKlish
measure

0.000046

0 . 000058

0.000073
0.000085
0.000122

for metric
measure

0.00015 0.0000045
0.00019 I 0.0000133

0.0(M)24
0.00028
0.00040

0.0000600
0.0003500
0.0007000

The Chezy Fonnuia. — This is

v^c^RS
W which 9 » mean velocity in feet per secrond,

As hydraulic mean radius or area divided by wetted perimeter,
S = slope or ratio of fall to length,
cb coefficient varying with,

first, the roughness of the wetted perimeter decreasing with
the increase in the roughness, most ra[)i(lly when R is small;
second, with the value of the mean hydraulic radius, R, in-
creasing with its increase, most rapidly when R is small;
third, with the slope, S, decreasing with its increase in large

78 AMERICAN SEWERAGE PRACTICE

streams and increasing with its increase in small streams
(Ganguillet and Kutter, p. 22).

The formula is essentially empirical in form but it has long remained
the one most familiar to engineers, and as substantially all of the later
results of experiments have been applied to it, as well as to some other
formulas, the limits of its applicability have been better established
than have those of any other formula for the flow of water in pipes,
conduits, canals and rivers.

The determination of the coefficient c under different conditions has
received much study from hydraulicians.

The Chezy formula may also be written in another form, which is
attributed to Weisbach (see Coxe's translation of Weisbach's "Me-
chanics,'' p. 866).

in which h/ - the head loss, in feet, in friction in the given length and

diameter of pipe,
/ = the coefficient of friction, which decreases with increase in

pipe diameter and slightly with velocity of flow,
Z = length of pipe, in feet,
d = internal diameter of pipe, in feet,
t? = velocity of flow in pipe, in feet per second,
^ = acceleration of gravity =32.16.

These two forms of the Chezy formula have been arranged by Hughes
and Safford ("Hydraulics," 1911, p. 285), as applied to the flow of water
in pipes, in the following manner:

V = C{RS)^; or hf=fLV^/D2g

For uniform steady flow in circular pipes:
The mean hydraulic radius, R = D/A
The slope of the hydraulic grade line, S = hf/L
The area of the stream, A = irD^/4: Then:

The friction head, ///= ^^jy » or hf=f j^^

The mean velocity of flow in feet per second,

The discharge in cubic feet per second, Q = AV— . —

in feet required to deliver a given disch

The diameter in feet required to deliver a given discharge,

HYDRAULICS OF SEWERS

79

Compariaoii of coefHcieuU C and /,

-(?)'-'

. , ^ 257.28

THE KUTTER FORMULA

the engineers who have given study to the correct determi-
t of the coefficient c to be used in the Chczy formula for the flow
o( irnUM- in pipes, conduits, and channels, were the Swiss engineers,
j CaQguillet and Kutter, of Berno. Tlicir results were first published
l^iEi a series of artiele^s in the German technical press. They were first
^ftan^atod into English by L D'A. Jackson (London, 1876), and again
^^ft|Aii(iolph Hering and J, C, Trau twine, Jr., in 1892, who presented
^^^^ with additions in a volume entitled^ ^*A CJeneral Formula for
I the Unifijrm Flow of Water in Rivers and Other Channels, by E.
aillct and W, R. Kutter, Traik?lated from the German, With
»ufl Additiooa including Tables and Diagrams, and the Elements
1200 Gagings or Rivers, Small Channels and Pipes," ono of our
iD engineering classics.
Ig lU general form,

I . m

'+ n*-S

I

\/s5"

luee fl, I and m are constant and n varies with the degree of
Substituting the numerieul values found for the constants
rir mf»n.sure, 0 5^23, / = 1, m = 0 00155, we have in metric measure,

23+,; +

1 . 0.00155

S

3bli measure,

■-K-^)vi

]y/RS

41.66+---+ -^~

.+ (41.66+««f>)

V^

^^RS

p - Ibe moan velocity of the water,

ff •thti hydrnulic mean riuliua,

S •' »lopn (if water stirfaoe ppr unit of icnKth,

' '-ient of roughness of the wetted perimeter.

Vat «><•. . if rouglincss, n, wit h llioir ret-iprocnls, etc., Ganguillet

I Kattiif Buggo^ted (p. til): tho valuea in Table 10.

80

AMERICAN SEWERAGE PRACTICE

Table 10.— Values op n in Kutter Formula

n

1
n

-^-

1. Channels lined with carefully planed boards or

with smooth cement.

2. Channels lined with common boards

0.010

0.012
0.013

0.017
0.025
0.030

100.00

83.33
76.01

58.82
40.00
33.33

123

106
100

82
63
56

3. Channels lined with ashlar or with neatly jointed

brickwork,
i. Channels in rubble masonry

5. Channels in earth, brooks and rivers

6. Streams with detritus or aquatic plants

In Hering and Trautwine's translation will be found in English
measure, the results of 1200 experiments made in different places and
countries up to that time, 1892. The more recent determinations of
the coefficient of roughness n, for use in Kutter's formula, made chiefly
upon sewer pipes, conduits and channels, have been summarized below.

Lowis D'A. Jackson's translation (1876) of "Kutter's Hydraulic
Tables" cites the following values for use in Kutter's formula (p. 74):

0.009 WoU-planed timber

0.010 Plaster in pure cement

0.011 Plaster in cement, with one-third sand

0.012 Unplaned timber

0.013 Ashlar and brickwork

0.015 Canvas lining on frames

0.017 Rubble

0.020 Canals in very firm gravel

0.025 Rivers and canals in perfect order and regimen, and

perfectly free from stones and weeds.
0.030 Rivers and canals in moderately good order and regimen,

having stones and weeds occasionally
0.035 Rivers and canals in bad order and regimen, overgrown

with vegetation, and strewn with stones, or detritus of

any sort.

Lowis DW, Jackson made in 1877 and 1878, at the request of the
Indian Govcrmnent, an independent determination of a set of values
of n. His figures were obtained from experiments on water works in
South America and in Northern and Southern India and from official
records in several other countries.

"Briefly, the results were, that none of the cases in canals in earth were
below 71=0.017, that the cases in which n= 0.025 was approximately appli-
cable were not canals in by any means perfect order, that any channels of a
condition suited to n =0.035 were from irregularity beyond the scope of
anything but excessively coarse and almost useless determination and that
a large number of cases of canals in good order happen to give a value of n
not far from 0.0225."

nVDRAVUCS OF SEWERS

81

•* Five £jced classes were therefore asaigned to canals in earth of various
Dilfi, and in various conditions.
Fmt » =0.020 for very firm, regular, welJ-trimmed soil,
6<M9Qnid n =0,0225 for firm earth, in condition above the average,
Third n =0.0250 for ordinarj^ earth in average condition,
Wmrili n» 0.0275 for rather soft friable soil in condition^ below the

average,
Fifth n =0,030 for rather damaged canals in a defective condition,
**Tlio attiitn|Jtj3 of the author (Jackson) to determine independently
J«c« of n auitcil to canals in artificial materials, plank, rubble, ashlar, and
Irement, were ineiTectuai from want of sufficient mention of age, quality and
leondition of surface of these materiaLu in recorderl cases of experiirient then
iliirlhcnrning. For the special material^ rubble, these Intter did not afford
Iqiiite sufficient reason for objecting to Ilerr Ktitter's value of n =0.017 for
llh*t material in a norraal condition, but they did indicale a wide range of
fftlaoB; as to other materials, nothing resulted on account of the reason
I before given; the general conclusion was that each material should have a
wilier range of values of n suited to various conditions. Accepting, there-
fore, the normal vahics given by Herr Kuttor as correct, the extension of
tbetf range wa« effected by the following arrangement.
n = 0.010; Smooth cement, worked plaster, planed wood, and glazed

surfaces in perfect order,
n«0.0l3; The materials mentioned under 0,010 when in imperfect or
inft^rior condition. Also brickwork, ashlar, and unglazed
etoneware in a good condition.
n* 0.017; Brickwork, ashlar, and stoneware in an inferior condition.

Rubble tn cement or plaster in good order.
• "0,020; Rubble in cement in an inferior condition. Coarse rubble
rough-set in a normal condition,
'0.0225; CtJarse dr>'-«et rubble in bad condition." (Jackson, " Hydrau-
lic Manual.*')

Major AtUn Cunningham (1874-79) carried out experimentj* on n
«'ale on ihvi Upper Ganges Canal in India. The total

1 1 y moasuroments was 50^000.

"Aft*T dbcnming various known formulas for mean velocity, the only
Btt« thai appeared worth extended trial were Bajsin's forroulaii for the
aorf^Hfrnt^ ,-* and a, and Kutter'a for the coefficient c. Aa to Bazin's two
fo*' (, a) the discussion shows that neither is reliable ♦ ♦ ♦ • •^

ii 1 r 4 c«MtfHcient c, the discrepancie^s between the ?i3 experimental

Cfimputorl valuer were: thirteen over 10 per cent., five over 7 J per
k. ftftaen over - t"'^ • -^'^t seventeen over 3 per cent., and tlurty-tliree
toider 3 per cent.

* V in all Ihr It ^ over 10 per cent., it waa found that the

wml^r wiM* nil for the slope mea-suroment. Taking this

ill' varied evidence in Kutier s work, it seems fair

te .' 1 1 OS of pret ty general applicability ; also that when

Um tmimxm iiiopc meaMurenient is good, it will give results seldom exceeding

82

AMERICAN SEWERAGE PRACTICE

7 1 per eent. error, provided that the rugoaity coefficient of the formula is
IcDOwn for the site. For practical application extJ-eme care would bo rie«*c&-
eary about the alope-measiirement, and the rugosily coefficient eoidd only bo
determined, according to present knowledge, by special preliminary experi-
ments at each site.

*' Much special experimenting was done (with surface slope measurement)
and with the «lefinite result that Kutter's formula wan the only one not re-
quiring velocity measurement of pretty general applicability, and would^
under favorable condition.^, give results differing by not more than 7 J per
cent, from actual velocity measurements. This was surely a definite and
important result/^ P, J. Flynn, ** Irrigation Canals."

C. D, Smith reported before American Society of Irrigation Engineers
(1894):

*' I have found the coefficients of roughness in streams recently put in goofl
order and regimen to vary from 0.020 to 0.027.'j, while if both coefficients
were used in the same canal the difTorence in rej^ults would be over 40 per
cent. 8till engineers will usually use the coefficient 0*025 for all streams
of this kind.

•'Below I give a table of coefficients of roughness deduced from personal
experience. Tests were made with current meter and weir. No difference
has been designated between the experiments by the weir and meter measure-
ments, for when comparisons were made» in similar streams, the results wer©
found to be the natne.

n =0.020 firm soil trimmed with shovel.

n =0.021 firm soil, the hanks worn tolerably Hinooth, the soft dirt being
worn off leaving siu-face of liank rather uneven,

n =* 0.022 clay, with some loose gravel.

n =0.023 clay, where velocity is not great enough to wear the b
smooth.

n =0.025 new ditch in hmm or clay, as usually left after completion wl
carefully constructed.

n =0.026 hanks sloping, with weeds occasionally along the banks,

« =0.0275 piu*e sand uniform cros^-section recently put in good order.

n =0,040 grown up with weeds, in the center the weeds do not reach the
surface.

ti = 0.045 ditch in bad condition^ grown up with weeds."

Theodore Morion (1901), in an admirable article upon **Flow in
the Sowers of the North Metropolitan Sewerage System of Massui-
chujsetts" (Trans. Am. 8oc. C. E,, Dec, 1901, p. 78), gives an account
of gaging^ made in the Metropolitan sewers with a current meter.

*'The points selected for carrying out these observations wmn at manholcq»
located some distance below the pumping stations, where the flow was Inns
from any liisturbing influence of the pumps. The points were alwiut 80<>
fL below the stations, in each case, and were far removed from any changes in
alignment, cross-section or grade of the sewer. Below the East Bo^t nn i>ump-
ing ♦station the cross-section of theM.nver is a 9-ft, circle of 12-in, biM'kv^urk,
eemeotr washed, with a hydraulic gradient oC 1 :3000. Only one tuuall local

3

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8.8

24.8

9.1

28 I

9,4

31.

s.oo

18 24

8.25

21.35

8.67

24.69

8.98

28.35

9.29

32.32

9.60

36.65

9.91

ih

'so

2fi 3

9 0

29.5

9.3

33.9

9.7

39.1

10.0

44.7

10.3

50.6

10.6

57,

''»

45.8

10.4

53.1

10.8

60.9

11.2

69.5

11.5

78.7

11.9

88.

f' r*

63.2

11.6

73.2

11.9

84.1

12 a

96.0

12.17

108.8

13.1

122.

bO.TS

05.4411.21

76.28

11.65

88.29

12.06

101.27

12.46

115.34

12.86

130.70

13.25

147.

iM >

7' \

f^t.8

11.8

94 8

12.3

108.8

12,7

124.1

13.1

140.6

13 5

158,

J.3 1

k- , ;

100.5

12 2

116 3

12 6

133.5

13,1

162 2

n 5

172 5

IS 9

194.

l.a

mA

n.7

114.6

U 2

132 7

12 6

152 4

13 1

173

196 6

13 9

221.

0.1^

nri

10.56

109.22

10.97

126-41

U.37 145.16

n.76

16^^. _ <, 187.45

12 51 211 J

tPtmiUtJ- '■'.'— AA^ H

V^dniii

i j™»**"

■■■■

^^^^H '^ H

^BpSS^^S^^tlj RM^oLiu^n^^^^^d^ormmtml mmmi^M

:r ♦ jUv. [ -r; rs. I .itaif! 1

i

t

^^^^^m

!;■"

4n,i U.

(..»r. ivi f.><.,i *i tMMWiilt

i

* 1 * r. i » » 1 . » 1 J

f M

[1 > ^^H

«? l.-BS

r.u

K *L

f.' «

^•^^'^1

*i,iir*

Qa.Q

Its. Si:

.'',

yois

TO. 8

^^^1

<>t

T.:t. i

f>01

IM

T.«

it.w:

)s.e

ir

0.00

^.Of

ijia

f.i'

^^1

^^H

•f 1 iK

tt.tl

e s?

^M

. -^ jH

^^H

,i

in',ui ^^ iiUM^tl

CS,^ 1

m.a

""HI

•'.-VI

j.j.i

■ ■■ - 1^ . . 1 .. . _

'^H

11,1

7.1

It.:

j

^H

e.5

12.7

7.1

17.6-1

1

i^^l

^H

5.02

12.06

&.44

16.65 6^V ij^H

^^^^^^H

HYDRAULICS OF SEWERS

83

oaniiectian enters ihb stretch of sewer* No changes m ^nde occur within
a dtotaace of 70(X) ft. below the pumping atation. At a point 2000 ft, below
llir T z station, there is a change from a circular set^ion to a horseshoe

«»i ' i ^ainc equi%^alent area. This aectiou continues for a diHianre

oif 1* t itul <hon returns to a circular section. Below the Charleslown
ptiiii I.I,, iution, the crose-section of the sewer it* G ft. by 0 ft. H in,, basket-
liAfitile, of 8-in, brickwork, cement- washed, with a hydraulic gradient of
J :20O0. The cros^-section ami grade are uniform for a distance of about
SOfliJ It below the pumping atation^ and no loc&t connections enter the sewer
vttliin thia dLMtanc^."
Th« r«Kult« of the test arc shown in Tablo 11 and Fig. IS.

Tahij: 1L — ^Values op n in Kutter Formula Determined from
GAyiXGs or a Cement-washed Brick Trunk Sewer (Horton)

Sflfitfa of JuJy, lS9ft— Chariestown Purnpinj; 8UitioD

.w

^ .. Q in cu. ft

viflocity

Uydrauitu
reditu

c

n

1

1 02

8 00

1 00

0 688

107

o.ouo

It

1 44

16. 59

2 46

0.068

lis

0.01.11

III

1 91

2U.81

2.82

1.187

116

0.0i;l2

t:'

2 40

38. «2

3 13

1-387

118

0.0133

2 80

62.00

3,44

1.630

124

O.OKJO

»<irim of July. I»9«— Ewt Boatoti Pumping SUtton

1.02

0 10

1.68 0 610

no

0.0122

If

K&2

16.07

2.21 0.028

126

0.0117 '

ttl

2.04

20-40

2.70 1.208

134

0.0116

Vf

3 46

42,18

3.03

1.408

130

0,0116

V

3 I<1

fl0.6O

3-48

1.830

141

0.0117

VI

:i T.'i

Q4 <V0

3 73

1.909

146

0.0116

1 :- (H) \

4.18

2.300

160

0.0115

II '• rnber» 1807— Cb«de»towo Pumping Stalion |

1

. 1 4a «7 2-97

I. MO

107

0.0140

1
1

-1 56 H 3 W

1.660

in

0.0H7

u'H of Snvan, H<i«toQ Ptimpin* Sutian

^ J :.

30 ;

1-280

123

0.0120

II

2 74

47 7' 2 00

1 660

127

0.0127

III

, a to

©2.iJa sm

1.762

120

0.0129

IV

S.20

64 S2 I 2.18

1 771

131

0.0126

^Hm of IvLw, 1000— Chjkiictt own Pumpinir dtation [

1

2,29

S0.g2 2,m

1.342

102

0.0161

It

2 7ti

41 30 2 80

1.608

104

0.0152

rn

a 30 \ 63 00 t S 04

1 646

106

0 0162

«l»ru>« of April* 1000— Eiujt Boston Pumping Stution

24 00

2.38

t.130

no

0-0130

1 1

48, 2B

' 2.82

t.ooe

121

0,0132

jji

1 :a m 1 70 78

3.16

1.062

124

0-0J33

IV

4 U ! f»A S4

3 no 1 2 130 1 124

0 0131V

fT«>rtoit 4)aiidudod among other things that the greatest change in

il Mirfjioc of the iiowera took place soon after the channels were

l}<ii inui operntiont the initial coofficicnt of frietion n^ for use in Kutter's

84

AMERICAN SEWERAGE PRACTICE

*

If"

^

t

]

¥Siir,dlQ^ itPQ

So
S E

si

ij

rf

i

i

i

1

\

V

\

in. tM — 2

I

0
E

" S
o>

c
a

6

HYDRAULICS OF SEWERS

85

duIa beiii|5 between 0.010 and 0,011, the Charlestown channel
jfmg filightly the higher value. lu comparing these changes in the
I of n with the actual condition of the channels^ it should be kept
that:

{"Tbo Eii^t Boflton channel ia of 3 ft. greater diameter than the Charles-

nbaimtil, tb&t the invert of tho East Boston channel is approximately

. iboivo mean low water, while the Charlestown channel is 4 ft. below

kU>w water, ami that the Ea^t Boston channel receives relatively leaa

1 water than the Charlestown channel, and ir, oon.9eq neatly, subject

► l©*- 6uctuation of water Hiirfare. The importance of this last inDiteuce

at from the fact that the deposit of both grease and organic growth

kI in greater abundance on the sides of the channel, and was greatest

be hne of average flow. On the bottom of tlie channel there was

ally r>o fleposit; resulting, no doubt, from the scouring action of sand

particles transported along the invert by the sewage. Thia

'V no mean^ novel, and has frequently been obaerveil, though

I i }am cirtcnt, in wat^r-supply conduits.

*'Tht effect of the density of the aewage upon the carr>*ing capacity of

thftse cloLonelis appears to be slii^ht, in view of the fact that the observations

;nui.t|r under all the var>^ing conditions of storm and drj^-weather flow.

ipcwBlblo i?frect of cleaning or scraping, however, might l>e much greatefi

, it tbif date, no cleaning of any aort baa taken place in these channels. '^

trMur r Sajjord, and Uonard Metmlf (1004) reported

** determination of c in the Chezy and n in the K utter

nuta, as applied to extreme flood conditions upon tho Merrimac

tat R4*edV Ferry, N, H., as developed from observed water levels

rit nparby points upon the river. The discharge was approxi-

-u. ft. per second; velocity, 3.96 ft. per second; R, 26.5j

per 1000 ft.; coelHcient c, in Chezy formula, 55; coef-

mii, in Kuttor formula, 0.055, This result is not to be assumed aa

but a fair approximation for such extreme flood conditions

^Ihe Merrimac River,

i\ Bafjb f 100t>) reported (Eng. News, Feb, 1, 190(>) nieasurements

I in an irrigation canal near Kimball, Alberta. The cunal wai^ In

riy good order, being free from woods and the banks well preserved.

yoi valuer found for n in five experiments was from 0.021 to

lavoragc being 0.02.30.

I C. Cajffin (11>01>) rejMjrted the coefRcient of roughness which
in the Cambridge, Mass., conduit— built under his direction
W06, of Portland cement concrete, the surface of which had been
hod wnth neat cement— ^ as being approximately
«' observed conditions of flow\ Those were, depth
^fLIn circitlar cotuluit fk'i in. in luteriuil diameter, laid upon a slope
f 3 In per Uiciusiin'f ^"*t

86

AMERICAN SEWERAGE PRACTICE

EYDBAULICS OF SEWERS

87

J, B. LippincoU {Eng, Netva, June 6^ 1907) summed up the results of
h 6xp«ritDeQt8 in cauals in South California thus:

I 9

~~~~--

.^

^^

«^_

\

\

£

\

\

\

^

\

fin

S

/

/

s

/

J

f*

/

/

/

^

1

D9H

7

y

j/

.^

4

!

/^ .

2

O :
as ^

god

"I

|§

g«

li

^ I
^<8

I

I rorn thoHG cxp<?rimcnts that a coefficient of 0.012, for

L. ^voutdbesofe in timnela or covered concrete oonduita

^*t4in7«i -iiti,.r. For open oimcrcto work, whoihef plasteretl or

vcKctud'ti \^ould occur, the value of n should be increased to

riiHillta

■H

88

AMERICAS' SEWERAGE PRACTICE

0.016 or 0.018. Where the grades of the conduit are so flat that velocities
will be inarlequate to keep the channel scoured, and under oondit*onfl where
silt occurs in the water, a value of n =0.020 or more should probably be used.''

Diuhamt 4$t.U

MtanyUocrty 2.6/
HfdiauUclhdiin 4.Zb

n SndeO.ifOOlif
CodHeknt "c" «Z.6f
• •/?• O.OIiJ

Earth

— Sunnytide Canol Z7.Z Mile»from Head —
ConstrucfBd 26 fh Bottom Width, 2fol
Side Stapn, 5ft. D^ andHydr. Orgdtt

— Sunnyftlde Canal 2ft.6 Miles from Head —

€anal -ij
ctsEiMvalwd^

10 to 30 40

— Sunny side Canal 294 Miles from Head •

—Yakima Volley Canal ~
tartHand6rav€f. At County
Roadntar North Yakima.

( Dischargf 465.11
I MtanUrha'fy 2.3$
I Hydraulic Radha 4.U
\ " 6rad€ O.OOOm
I Cotffiuont "c' 55.14

Dischargf 442.10
Meanmcity 2.7$
Hydiauiieltadks 3.7$

n erode o.ooom

Codfiditt V/00LO4
f 'n' ojom

' DiKharqf 55.45

MtanWocitf 1.1$
Hydrauliclhdka 1.79

n 6md€ 0,COi
Coafh'dMt "c"

» "n' 0.024

— Union Oanal on Naches Avenue —
Between AStreet and Yakima Ave. in North Yakima.
Channel Stnaiqht Sides Irregular, lined
with Coarse Bravel and Boulden, Aver-
aging 20 Itu.

IDisctiarge 44.00
Area 12.00

Velocity 167

Wetted f^n'meter 540
MeanHyd.Radies 1.4$
Hydmulic 6rade O-OOOIT
Coefficient "n"* 0.051$

( diicharge

2c.f.A.

Area CrossSection

1.75

rrrTTew rrnirnctvr

Z.50

Velocity

1.14

l^eanHyd. Radius

0.5

Hydraulic (trade

0.00255

Coefficient "c"*

30.2

K. n "n'

0.055

—Small Distributing Canal —
In Earth, Much Overgrown with Onus
and Clogged with Dead leaves etc.

Fio. 21. — Coeflficicnts of roughiuvss of earth canals.

^reeman, Frederic P. Stearns, «//</ Jiunc.^ D. Schuyler (Eng.
1907) reported to the city of Los Angeles, in connection

£ L

HYDRAULICS OF SEWERS 89

iih ibe proposed plans for building an aqueduct to bring the new water
om the mountains, that —

ii(ge5t the iim of the following ODeffieienta in the Kutter formula:
' ir or open masonry conduits of cement or smoothly pb^tered masonry

I "For ct^increte-lined tunnels, or covered masonry conduits, n -0.014.
^For steel pipe with rivet headB and seama projecting on the interior
-0.016.
•*Fodre*rth canals with bottom as left by dredging, n =0.0275/'

Therrm A, NMe reported, in a valuable article upon '* Economic

Canal Location" (Proc. Pacific Northwest Soc. C. E., June, 1907)

kn vfUuiBs given in Fig. 21 for the coefficient of roughness in canals in

th, as determined in theSunnyside, Yakima Valley and Union Canals,

i ooonection with the Tieton project of tlio U. 8. Reclamation Service

l|ion the Vakinia River in the state of Washington.

The Bureau of Surveys of Philadelphia, Pa. (1909) had a series of

irmtions made, of the values of the coefficient of roughness, n, of

^utiuii of the largo sowers in that city, with the following result:

n

Old sewers, brick bottom not clean 0.017

Old wjwcru, stone block bottom clean, 0.017

Xew (lewenf, etone block bottom clean . 0,010

Kow M*wers, brick bottom clean 0.015

Coocreio or brick sewefi vitrified shale bntk ir;vcrt»

H*'«n . 0.012 to 0.013

' t^werfl, granolithic finished bottom.. .... O.Oll

ritjcl box, planed plank.^i ,0.011

Oiil mvf&m, bod or dirty bottoms . 0,017 to 0.020

iomw .4* Cmhmnn (IDM) in un interesting urticle upon ** Coefficients
[ tf IWin tlie Wachuj&ett Aqueduct,'^ of the Metropolitan Water Works
[ rf Boston, MasB. {Eng. Neu% Aug.

Acs a suiiimary of the ^.^g^g^gg^

JiJ , there. The section of /v^^'^'^^^^^'^K

iidait» Fig. 22, show^n here is / / '^ * v\

hoe in shape, lined with brick /n/ S v\ ^X

MWi iu invert and for a distance of / P *j* ^11 \

'iLr>r * ' ihovo it, the remainder ^^<«^\ T jj ^A

^ I and roof of the con- ^""^^^^^^^^^^g^^j^!^^
built of Portland cement

Table 12 giv66 informa- Fh^, 22. -Cross section uf

lAL^ Mil • J ^ ^L i Hachusetl aqueduct,
IW Avaaablo m regard to the rai-

j obwirvatitiu-H which were UHe<l to determine the value of n for
It below the top of the brick lining.

90 AMSRiCAX SEWERAGE PRACTICE

T.\BLK 12, — CotmciKNT OP RoroHXESS OF WACHrsETT Aqukduct

RaU&c J*t«

Aqucdaot U»t

Di^yvin use

Qflovioc

1 CoeflEdeni of

clmn^l

since eleaminc

e. f. ».

vpr avv IS«»

Apr. y 1S99- . . .

15 1

I7&.5

0.01239

VpT 21. ISQHt .

.Vpr. 5. liftW

16

145.2

0.012S8

M*y :.V 1S»

Apr. 5, 1S»

40

113 9

0.01234

M*> i:. lAV^

.\pr. .V ISW.. -

401

S9 «

0.01209

Mvr IT. IAV>

Apr. *, ISW

401

92 4

0.012S8

\u> * ;^v.

Apr 14. l^M

91

S5 «

O.OllSl

Vpr » :*^^T

rw 21, l*kV

u^

122

220 3

0.0120

of brick Urdo*

Mar 2*. IsVM

IVc S. ijJkVl

«6

350 5

0.0121«

r*^ i.v ;>»4;

Apr, 1,V 1911...

51*

4M 7

0.01153

M»r ".x :5i::

.Vpr l.V 1*1!

2,V

42S 4

0.01171

Wi:h tho c.x«*ption of two raiinp? in 11*00 and one in 1907, the ob-
s»on-»nv>Tj? wcTv nia<ie after clciininir. The invest ication showed that
a# :hr wator rose ahove the top of the brick lininij, the value <rf n
deoreA.<soii, and the coefficient of flow, r . in the Cheiy formula incmsed.

The A-^lues of n derived fiv U5*e in Kuiter s formula wei>e

Ftv the hricWinci ?urfaf>r 0 0123

For the <\-»TOh*iTiatioij i-*: hnri Jtaii coocreTe surfaw*. 0 011<S5

GftTviruilleT and Kaiier px^ for new ^relj-U-ia hrihkwork. 0.011 to 0.012,
hJid f.-»r <v»n>er.T ^-me-i hir.i sfcn.i . 0 01 1. It jvrnns reaj«ar«AK)e to aAmme that,
hai This o*in*i4iJT Seer. S.;i1t ein-ireN- of ftoiUfTeTe a^ sxniv*ih ai^ the upper part
«-}*.< b*.:ilT. thf vjj-.ir of t rc*\Xi h*vr beor. Tj^keii a* Jc^w wf 0.0112 «&d per-

The ^-fc-Jije? o: .* der.A-er' slu:! ')ir o»iar.i:T)f5s fiovjnp were a» fciDainE:

f

VJ

Ac!iie.i.i»"T ; '.i'.V.

:.^f

f.l n;x d.

Ao.io.Jj,

■I < :;:]'.

144

l?if iL4id,

AvMlOJij;

•I ; :ni.

IM

2T1 tt^r-d.

Acnt^.iii-

'■ u: iiii.vin.

.-TT.

rj»n«.-j:x

:.=is

aft.^ n.^ d.

AOi.'O.Mi

•: :;i\.

it*"!!

:^4P XL^ d.

di>Mi.iii "iriiM"' siiqce>:> a> *hf \iTTr.u';a :\ir ^if "0:71.1111111: ii>e value

Thr?** ■o~nii;.s> :i""( >nuij:i* :i '.fcTi T." Tli.isf ".■nwnf: for the f%iidhiinr«

o; t wm !ouni. J I in

12T' '• '-. 122.lv ' "• fcin-. ::'4- •»■

HYDRAULICS OF SEWERS

91

*Th« Suclbiio* Aqueduct gagings by Fteley and Stearns developed a
Ja« of ^

u^= 127/^"^* Vrjf=127r« •"«••*«

a pi^riion of this conduit where the brick lining was coated with pure
at, the coefficient was found to be from 7 to 8 per cent, greater than
7t*'^\ In another portion where the brick lining waa covered with a
flasu!Qt wash laid on with a brush, the coefficient wa^ from I to 3 per cent.
gr«ftt(sr. For a long tunnel in which the rock sides were ragged, but with a
ooooth eement invert H was found to be about 4Q per cent. less. Owing
lo iLe folding of such conduits as the result of vegetable growths and the
dtioQ of materials from the water, a diminution in capacity of from
10 lo 20 per cent, with age may be expecit^d, and accordingly correspontling
lallnwancea should be made in the design.** (Merriman, '^Treatise on
JHydmulics/* p. 30L)

Wtilier \V, Patch, 1902, then A^s^sistant Engineer of the Sudbury De-
lukfttnent. Metropolitan Water Works of Boston, in Eng. Netrs, June 12,
1902, p, 488, describes liis measurements of the flow of water in the
8ndlmT>'^ and Cochituate Aqueducts. *' While the methods of metering
thft flow lijerein discuBsed are valuable, the matter of greatest interest
'>cui5sion upon the rapid loss in carrying capacity of these
fill I cleaning and the determination of a coefficient of cleanll-

BiW which cold c I be applied, by meaas of periodic meter gaging? at
*rtlin stations upon the aqueduct, to the discharges computed by a
formula bascxl upon the flow of the conduit when clean, in order to give
M» iftual flow under existing conditions of cleanliness. These coeffi-
*^t* were found to vary from 89 J to 103*0 per cent, upon the Sudbury
Aqueduct, and froni 94.4 to 107 per cent, on the Cochituate Aqueduct,"
Mr. Patch concluded that '' unless the degree of cleanliness of the
tekrior of the aqueduct is known, the computed flows may be 10 per
*tot in error.*' The variation found during the period of one year is
•<iown in Hg. 23.
^e Mudden incr^aaes io the value of the coeflicient of cleanlineas are
^ a portion or the whole of the aqueduct.
ms will he found in newers due to the formation of
•'MO wirl growth?* adhering to the wall^, and deposits upon the bottom
^ the rtinduit.

'^^ ^^ Shertnan writee (Eng. News, July 27. 1911) that upon the
*'*'l'»^ I * Main Drainage Canal, values of n between

^^*). I tbsorved, the latter probably being the more

•"f^tis. The channel is im ft. wide and 23 to 24 ft. deep. The sides
•** vertical, channeled smooth in limestone rock; bottom rotigh.

'n Uio experiments Q varied from (HXIO to 8000 eu, ft. per second, and
•^ Irrnii I 1 100002. Thin clmtmel may be outside of the limiting

'*'*•» • rit value of n in the Kuttcr formula.

92

A. \f ERIC AN SEWERAGE PRACTICE

In a later personal communication to the writers, Sherman states
belief that the value n = 0.02iS to 0.020 for rock sections^ with smool
nearly v^ertical channeled sides and rough rock bottom, is probab]
reasonably accurate for the Cliicago Draiuage Canal. The best vaJ
for n found in earth sections was reported as being approximately 0.038,
but later investigation indicated that the section under observation
silted up considerably and that a redetermination would probably Bh
a value of between 0.033 and 0.035.

Fig. 23. — Deptha of flow and ooelHcienU of clejinlineas in the Sudbury i
Cochituate AqueducU.

John Ericson (1911) reported in a valuable article upon **Inv^ostig
tions of the Flow in Brick-lined Conduits*' (Jorur. Western Soc^ En^
Vol. XVI, Oct., 191 1, p. 657) values of n for several sections in the Nor
west land and lake tunnels at Chicago, which are circular in form,
follows:

0 01455, 0.01347, 0.01552, 0.01403, 0 01382. and 0.01385; Avera«e=

0 01435

"Part of this tunnel was lined with sewer brick laid in Portland cea
mort4ir, and the remainder was sewer brick Ifkid in Uiica cemeut morti
The bricks were fairly uniform in size and make. The workmanship
good, and while the mortared joints were not scraped or pointed, thcro ^
no unusual roughness of the inside surface of the tunnel apparent to
eye. Blasting was resorted to in the greater portion of this t nriiit«l, itml \X
may have loosened the mortared joints and ir>'
extent. Otherwise it was a .mmple of %ocn\ h\

**Tbe results in general soem to i:
brick lining, in such a manner that
eaeh disturbance is especially notice
creasing the resistam**' »o n,.ii u^.i

HYDRAULICS OF SEWERS

93

I

a tunneU The jarrmg of the brickwork undoubtedly disturbs the

mortar joints, more or lass, so ihat thp Ijond with the brick will be broken.

SUgbi prujections and irregularities will he r^auj^ed by this shaking of the

bridcwcirk and, irrespective of any visible disturbance or distortion of the

rofiifltanc^es to the flow of water seem to have been created.

**The author (Ericson) from \m experience with these as wellasother simi-

can^M* is of the opinion that for tunnels or sewers of ordinary sizes and

elocilieii of flow, lined with sewer brick laid in cement mortar, if the brick

i©cte<l and not too warped or uneven, laid in a workman like

Ptrue to line, not disturbed by blasting, and the mortar joints

oR^'fiu^h with the brick, a coefficient of roughness n in Kutter'a

formula of 0.0130 ia readily attainable, if the extraordinary resistances to

llow» 9urh a8 bonda, enlarnenienta, etc., are ehminated,

** Coder certain circumstances, especially if there has been any diaturb-
BMkmt whatever of the brickwork on account of blasting, it will be found
-^iftittble ami profitable to have in addition the entire interior surface of
bndc ooniiuite wiwshwl with neat cement, the strokes of the brush applying
Uie wiMh to be always longitudinally parallel with the axis of the conduit.
By ttiia method a coefficient of roughness, n, considerably smaller tlian
0 0130 flhould be obtained in wcll-construoted tunnels of the sewer^brick-

C, F. Schulti (1912) reports finding the coefficient « = 0,0151, for use
hi Kuttcr*s fornmltt* in a test of the flow of the Ea^t Side Tunnel of the
npvclaml Water Works. This tunnel was built of shale brick laid in
Tit mortar. The mortar projecting on the inner surface uf
aii roughly scraped after the centeri? were stnick, but no
^ifuiar pains were taken to make the work any smoother than ordinary
^'Hckwork. The tutinel was 2(i,000 ft. long and of 9 ft, nominal
r,

reU {Eng, News, May 1» 1013, p. 004) reports experimcnta
>- and 40-in- nMtiforccd concreto pipes built bj^ the United
-*tn It^rclamation Service* The.so results may be summarized as in
I ^ 13.

»*w.6 i^ — 1'^ii:tioxal Loss ts lt>, 30-, and 46-ix, Concrete Pipes
(U, U, Newell)

u

z.

V..IO0-

f.i>.iL

Totrtl

iricilon

8

per
1000

Che«y

formuXa

e

Kuttef*

form Ills

n

HMcn A

Willbmj
fornitila e

it^

46 ta

4 00

8 5:»

0.87

138

O.OII

140

^^^K

tft > ,

4a m

3.dM

7.08

0 78

145

0 0100

MM

^^^V

*t.

in 10

4 17

rn «i

I 08

r^a

0 0117

13(1

^^^K

• '•

iH 50

4.21

10 0.i

1.02

135

U 0113

135

^^^P

^iin

17 7u

:i rtl

5 48

J (»7

140

a 0103

148

r^

13

5 40

1.06

132-13:j

0 0108
0 01 Oft

142

;f.l3

a HO 1

118

O.OJIO

120

^^^1

2 07

3 8

7«

0.0154

82

^^^B

3 10

4 5

m

0 0134

08

■

1 71

I «»

08

0 0135

100

94 AMERICAN SEWERAGE PRACTICE

F. H. Newell (1912), Director of the U. S. Reclamation Service, m
a personal letter to the writers in answer to a question as to whether
his department had made experiments upon the different irrigation
canals and pipe-lines built by it, wrote:

"While some observations have been taken on the value of n by the
engineers of the Reclamation Service, none of these have been brought to a
final conclusion so that wc feel we cannot add with certainty anything to
the subject. In this connection I may state that most of the earthen canals
in the service have been designed on the assumption of n equalling 0.025.
Observations on some of the canals seem to indicate that this value is a
little high and it seems probable that final results will show that a value of
n equalling 0.0225 is more nearly correct. These conclusions are based on
rather incomplete observations on comparatively new canals operated at
partial capacity, as in most cases it has not yet been necessaiy to operate
the larger main canals up to their maximum limit.''

SUGGESTED VALUES OF n FOR SEWER DESIGN

In view of the facts cited, the writers suggest as reasonable values for
the coefficient of roughness n in Kutter's formula in the case of sewer
pipes, conduits and channels, under reasonably good operating conditiwts^
the following coefficients:

n

For vitrified pif)e sewers 0. 015

For concrete .sewers of large section and best work
liii<l on slopes giving velocities of JJ ft. per second

or more 0. 012

¥i)T corKTete sewers under goo<i or«linary condi-
tions of work 0.013

For brick sewers lined with vitrified or reasonably
smooth hanl buriuMl briok and laid with great

care, with el«)se joints 0.014

For l)ri('k .sewers under ordimiry conditions 0.015

For brick sowers liii»l on fiat grade and rough work.

0.017 toO.020

Although many encineers employ // = 0.013 for vitrified pipe sewers,
the authors favor n = {).{)!'} wlien^ the grades permit, in view of the
])ossil)ility of rough pipe iind jiunr pipe-laying, wJiich will increase the
frictiunal resistance. If //^O.Ol.S is assumed, great care must be taken
in specifying and accepting materials, to make certain that the char-
acter of construction required is obtained.

The Kutter formuhi is nio^t reailily used by means of diagrams. For
many years these were collections o\' curves plotted on onlinary cross-
section paper. The advantaiies of logariiiunic paper for plotting such
formulas gradually Ix^canu^ rec«)trniz»Ml. aiul in VM)\ John H. Gregory
prepared the iliagrains shi»wn in Ki^s. '2\. ■j:>. '2\\, '27 ami 28, which are
part of a series of labor-saving charts vlevised by him at that time. The

I § I

1 I I r f I Li 1. 1 I. 1. 1 I * ' « * « I 1 ' ' * I I I f I I « I » I < I

^ ^ ^ /9

-^ — 2r

I.I I

B3SIS 10 3B^AH0aQ QMlVta MA5
UO.Oan AJUMflOl 3*fl3TTU;< Ya

ff*oV) .RIO.O • m .WM^Ui lo 3

ij

^9s^$ g i^B

1

» 1

' 1

■

.-^i

E::j a

■

hM

1

^^

ttii

M

'r ,*f*fi

•e ^ fl

%

«

^^^fa*

illll

ll|l!ll||

U*1 10 3©'

•G 9MtVia MAI

r.fiq^nO .\^ tfMX) 740 0 - m .»qlq \a 'jjnjub4ia— -iiS Mil

'it

fe i:? i7 I? tf> >- >-
1 1 1 1 1 tltlif 1 ■ 1 i.ti

■ id 1

1

i ^

MM1±

ffltH+tz

aiUULltlUJj

tiiiii i i

iittsnnK

mil

!=^

ll»S#!3i»e«aiBil':i.

ri

;/iu-

Ik

Oj ^

rs 3"

. i 4 >.> t 1

i V ^^

'imr

'' 1 ^ Mi

.■lIKi

1 1

1 MfU>

^uiiiit/i VTOirn.* ti-jf|i|ifi

ijciHiffi

'.- c, 1

Iss

i^M

•^

•T' '.juvj :^-A! ^^ t'

!j.|||||||.|f^jl(i|j

w>5yy

it

^

^-'

1 " ' 5

!li^

^

-•».

■«=t]

r^« III %%%%%^%

10 3851AH0eiQ OMIVtO Hk%

efl3W3S a3SA.HB-Qa3

HTS3a JJUT QMlHMUfl

afO.O-n.AJUMHOl 5'^3TT(

T.rv.

5^\^'

I i i Ij

g ? S >- a> p c> |g g> a^

•V^nt^^.,•

0

1b.^^ ,

^y

I ill

I 4n.l

■ > h 1 1 i I , I . I * I * K i

nv

\ «p\^

& 9

19

•5 ^

r

10 aaRAHOSIQ QMIVia MATOAia
SH3W3e a3SAH2-a03

t=n.AJUMH01 e'raTTUX YB

t»<l -^^ — •ft^'llk

Iff^tk}^

(.\niiQnO.I\ »»Aj\3 rino ^ ».% .(s^\q\<n^;utdo§M — »d£ ♦mi

•y «■ T" - t

HYDRAUUCS OF SEWERS

96

ILE H. ^Values of c for Use in the Chezy Formitla

iV, 8,

HccUimutioo Service)
015 I Ol7J.020|.025?.030l

Slopg f -^0. 00005 <»1 in 20,000 « 0.264 ft, per mile

035 (MO .0501.060

0 1

TS

87

59

52

47

39

33

26

20

16

13

11

8

O 2

100

•»7

77

ftS

62

51

44

35

26

21

18

15

U

g

3

114

90

88

79

71

59

50

41

31

25

21

18

14

4

124

100

97

88

79

66

67

46

35

28

24

20

15

*\

139

122

109

98

90

76

65

53

41

33

28

24

18

H

150

133

U9

107

98

83

71

50

46

37

31

27

21

(1

15«

140

126

T14

104

89

77

64

49

40

34

29

23

' 5

17;(

154

139

vits

116

90

87

72

57 ]

47

40

34

27

22

1 ^

Ift4

ItH

14B

lafi

124

107

94

79

02

51

44

38

30

25

1 «

t»8

178

lOl

148

\m

118

104

88

71

59

50

14

35

29

1 ••»

21* i

1**1

lCi4

151

139

121

106

91

72

60

52

40

36

30

1 *

207

187

170

156

115

126

111

96

77

64

56

49

39

33

1 •

220

ItKl

182

lft8*

156

137

122

105

85

72

63

56

45

38

1 »

334

212

195

181

169

149

134

116

m

82

72

64

63

45

1 »

260

228

211

190

184

165

149

131

no

96

85

n

64

55

1 "

266

245

228

213

201

181

165

148

127

112

101

93

79

70

B_i«.

275

254

237

222

210

190

175

158

137

128

112

104

90

80

^ 1

Slope #-0 0001

-Un

1 0,0«0- 0.528 1

rt. per mile

0.1 1

90

78

«S

00

54

44

37

30

22

17

14

12

9

7

9.2 1

112

98

86

76 ;

69

67

48

39

29

23

19

16

12

10

9.> 1

125

109

97

87

78

65

56

45

34

27

22

10

14

12

ni !

136

119

106

95

86

72

62

50

38

31

25

22

16

12

H , ri

149

131

118

105

96

81

70

57

44

35

30

25

19

16

(\ s '

158

140

126

114

103

88

76

63

48

39

33

28

22

18

im

147

132

120

109

93

81

67

52

42 '

35

31

24

19

178

159

144

130

120

103

89

76

59

48

41

35

28

23

;

187

168

151

138

127

109

96

81

64

53

45

39

31

25

3

198

178

162

149

137

119

104

8D

71

59

51

45

35

29

4

206

186

169

155

143

125

111

94

76

04

55

49

39

32

•

Hb

195

178

164

162

134

119

102

84

71

61

54 1

44>

37

10

226

205

188

174

162

143

128

in

92

78

69

62

50

42

3Q

237

216

200

185

173

IM

139

122

102

89

79

71

60

52

1W?

24d

227

211

197

185

166

151

134

114

100

91

83

71

ttll

as^

234

218

204

191

172

158

140

121

108

98

91

79

70

Slope 1^0.0002- 1 in 5000* 1.056 fl. p»r mjk

179

74
93

103
112

122
13]

110
I )*i

163
168

no

185

•V*

65

59

48

4t

32

24

18

15

12

9

83

74

61

52

42

31

25

21

17

13

92

83

09

59

48

36

29

24

20

15

100

91

76

65

63

40

32

27

23

17

111

100

85

73

00

46

37

31

26

20

118

107

91

79

65

50

41

34

29

22

123

113

96

83

69

54

44

37

32

24

133

122

106

91

77

60

49

42

36

28

140

129

lit

97

82

64

64

46

40

31

149

137

119

105

89

72

59

51

45

35

156

U3

126

111

94

76

63

55

48

38

162

150

132

117

urn

82

69

60

53

43

170

158

140

125

108

89

76

67

60

49

180

108

119

134

117

98

85

76

68

67

189

177

ir>H

143

126

108

94

85

78

66

194

1K2

i«:i

H«

131

US

99

90

88

72

•affJ ili«t

lor &U doped wltcn r -3.28 ft.

96

AMERICAN SEWERAGE PRACTICE

Table 14. — Continued. Values of c for Use in the Chezt Formti

PI

M(B

,010]

,011
' 81

,012

,013

,015

.017

.O20j.025r.a30

.035

.040

,050| M

r

rjpe *-

00

O.orxu-l Id 2500-2.112 ft, p«i

miU

0,1 1

"loT

80

7S

C2

60

43

34

25

19

16

13

10

1

0.2

12a

110

97

87

78

05

54 '

44

32

25

21

18

n

10

0.3

13H

120

107

96

ST

73

a2

50

37

30

24

21

1«

11

0.4

148

!2*>

115

liH

91

70

08

55

42

33

27

23

18

u

0.6

157

140

126

113

103

87

75

62

47

38

31

27

2ti

11

O.H

166

H8

133

121

110

03

81

67

51

42

35

m

n

Ifl

1.0

172

!54

13fl

125

115

98

S5

70 ;

55

45

37

32

25

»

1.3

I §3

164

148

135

124

loe

93

78

61

50

42

37

3S

n

2

100

170

154

Ul

430

112

98

83

65

54

46

40

31

M

3

im

179

162

140

138

lie

105

89

71

50

51

45

35

n

4

204

1S4

108

154

142

124

no

04

76

63

55

48

38

31

0

21 i

191

175

161

140

130

lie

00

81

60

m

53

43

90

10

219

138

1^3

168

157

133

123

m

as

75

06

59

48

41

20

327

207

190

17a

164

140

131

115

£M ,

83

73

m

55

a

50

235

215

198

184

173

154

130

12a

104

01

83

75

63

»

r

of

231^

no

21»

203

189
[ope Ji

J^77

-o.on

158

143

127

lOS

m

«7

80

is

Ji

1-1 ii

1 ioa<

]-'5 2Bfl. per

mill!

i>T

83

73

65

54

45

36

27

2t

17

14

10

^

0.2

120

113

00

m

81

63

57

45

34

27

22

18

13

11

o,a

Hi

124

lOO

98

80

74 ,

63

51

30

30

26

21

14

n

0,4

150

131

117

105

OB

80

60

56

43

34

28

24

IE

14

on

tin

142

127

115

104

S8 i

70

03

4g

30

32

27

21

17

0.8

im

150

134

122

111

04

82

68

52

42

35

30

23

11

1^0

175

155

130

127

un

90

86

71

56

45

38

33

25

90

1,5

184

165

14S

130

124

108

93

78

62

50

43

37

m

S4

2

UH

171

155

142

ISO

112

98

S3

60

54

40

40

31

m

3

19P

170

163

140

13H

110

10$

m

71

59

51

45

35

2t

4

204

IM

168

154

142

124

110

03

75

03

M

48

3S

3X

0

211

im

174

160

149

130

lie

n

81

0«

59

m

42

m

10

21S

107

1H1

107

155

136

122

105

S7

74

05

6&

4T

40

20

226

205

18S

175

loa

144

129

113

04

SI

72

es

54

47

50

232

212

106

182

170

151

137

120

101

80

70

72

81 H

T

0,1

236

216

200
S3

186
74

174
-0,0

155

141

124

105

JM

&G

77

66 !»

I - 1 ir

I 100

-52.8 ft. per in

il«

110

m

54

46

30

37

21

IT

14

10

S

0.2

130

114

100

DO

, 81

67

57

46

34

27

23

19

14

11

0.3

143

125

111

100

00

76

64

52

39

31

25

22

16

13

0.4

151

133

no

i07

B8

82

70

57

44

35

20

24

la

11

O.fl

WI

ua

120

110

106

90

77

64

49

39

33

28

21

17

OJt

170

151

135

123

112

95

82

68

53

43

35

31

23

It

10

175

15i:i

HI

128

117

90

87

72

66

45

3S

33

25

' 30

15

inr>

11^5

140

136

12,'j

107

04

70

02

51

43

37

Si

M

2

Itii

171

155

112

130

112

09

83

06

56

46

40

31

»

3

109

170

H12

140

138

110

105

80

71

50

51

45

35

0

1

204

1H4

Hi7

154

112

123

109

03

76

63

65

4S

as

31

n

210

imj

173

liiO

148

120

11^

90

81

68

50

52

42

M

m

217

106

1^0

IfiG

154

136

121

105

86

74

05

58

47

40

2U

225

2^U

If^T

173

101

14:1

123

112

03

80

71

54

59

4«

fill

2:n

210

191

IS]

li;8

150

135

119

100

87

7&

71

eo

51

IfH!

^:trj

2H

lin

ISl

172

153

130

122

104

91

82

75

65

Si

\ott. — For vlopea grourer than 0.01 c rvmuina nearly constant.

98

AMERICAN SEWERAGE PRACTICE

Valley concrete sewer he used h = 0,015. On branch lines of vitJifit^d
pipe he iised n — O.OVS,

T. Chulklrlf HqUou reports the results of experiments on the flow
of water in two 24-in* sewers built with 3-ft. lengths of pipe jind with
cement joints, at Carlisle, Pa. Experiments on a section 4660 ft
long having a grade of 0.077 per cent, and having bends at five maw-
holes with depthj:* of water of 5 and 12 in., gave n = 0.0128 anfl
n — 0.0112, respectively. One experiment on another section 2(J9o ft.
long and having one bend at a manhole and a grade of 0,04 \wt
cent,, gave with a depth of 12 in. n = O.Olll, as computed by the
authors from Mr. Hatton's data.

Alexander Potter reported that he was of the opinion that for vitrified
pifje and small brick sewers the coeBicient of roughness ranged from
0.013 to 0.0145, and the value of 0.014 represented average con'I'tinrK^o^
roughness and depth of flow found in practice.

This practice is based to a consideral»le extent upon the results "*
observations made on tlie joint trunk sewer system in north east e*"^
New Jersey, where the contributing flows from various muniripahti^^
are measured by 13 automatic gages keeping a continuous record of tk*^*
depth of the di-^charge. Once a week the charts are taken out and n^^
blanks substituted, and as a check on the readings of each chart ^^

Table 15. — Measured and Computed VELocmRs ani>
CENT AGE Ratio. (Pottee)

H^V,, measured velocity, fe-et per aecond; C V., eomputiHrl velorityt P H

ItuMo

|>1 .Irjtlb of How to
dit« meter

0 20

0,30

0.40

0.50

O W)

hf 70

Gfl«c No- 60 . ,

42- in. brick 8«w«r.
0 VA% ftrade., . . . .
Giicf! No, 53i....
20-ift, pipe seiref . .
0 . 28 % Kmcle ......

Gm^ No. i»

22-in. pipe sewer. .

0.6'*;, israde..

Ga«e No. 35

24-in. pipe *ewer. .

0.18% grade

Gftge No. 72

22-Ia. pipe «ew«r
0 22% imdm

M,V,

.. . .

3 19

a 08

3.45
3.4tt

3.R6
3.77

t\V. 1

^ PR

103 3

08.9

00,8

on *

2.30

2 70

2.02

8.30

aso

C,V,

2.20

2.00

3.05

3.30

3 15*

PR

107.2

100.fi

U.7

07,(1

on &

MV^

i 2.*i

4.81

5.20

n.h^ '

V,V

4.27

4 85

5.24

a 43

[PM
M.V

09. i

00 2

00 y

2 18

2. SO

2-73

2 ''

c.v

t 06

2.40

2 72

2 :' '

1

PH. ,

Mr.

lU-3

104 2

-m

1 78

2 05

2.68

M

► ■

r \\

1 «2

2. OS

2 55

M

PR

ino s

f»9 7

0« I

M

Pcre«tiUs<> miiQ of 100 corrmpoiids I0 n«0.011»
Pvrccntttic^ ratio ol 100 corrcapoad* to « ••OOII.
KrrcealKtfD rtiiio tit 02 eurrmpuiids to fi^O-Ut^

operator detemrmos tho achi
the velocity of t ^

HYDHAUUCS OF SEWERS

99

ratiom mmlo in 1906 to 1000, inclusive, on sewers built in 1903, ijre
1 in Table 15.
Mr. Potter was of the opinion that in a sewer wliich had been in use for
&m€ time the coefficient of roughness wa.-s a minimum when the sewer
[>wed loss than thrce-eightc' full* Under such conditions the coefficient
k al>out 0.0 i:i, he believed. As tlie depth of flow became greater than
ittc coefficient of roughness apparent!^^ increased, especially in brick
"iewers, he stated.

Effect of Variation in Assumed Value of n.^ — Ernest W. Bchoder

^nff. News, Aug. 22, 1912) called attention to the fact that the per-

Sje error resulting from a >vrong assumption as to the value of the

Icient of roughness n can readily be approximately detemnned for

Ic Kutter and Bazin formuliP in spite of the apparently complicated

Iturr ttf Wiiir rtn^^icwuis. IWomUy speaking, the following relations

.Id

ihi' .sinf>e ,s vanes i\s ^r, ahnost exactly for all values of the hy-
lic radius r greater than 1 ft.

The velocity i' varies inversely as n, exactly for r>= about 2 ft. and
^proximately for other values.

Corresponding to these relations we may state that a certain per-
itage of uncertainty in the value of n produces:

Double that percentage of uncertainty in the slope necessary for a
led discharge.

2. The »amo percentage of uncertainty, but in opposite direction, in
lie velocity of dii^cliarge re^sultlng from a fixed slope, if the slope is
ned to be greater than 0.000 1,

I an illustration of the convenience of this knowledge^ suppose that
dei^igiung a canal, it is uncertain what value in the range between
IL017 and 0.020 to chooae for n. This is an uncertainty of al»out 8 per
Bnt. either way from the mean value and represents a probable occur-
Boee in practice. We can state at once that the uncertainty in dis-
^arge aa caused by ignorance concerning n will be about H per cent, and
required slope, about 16 per cent.

The diagrams prepared by Schoder are given in Figs. 32 and 33;
reference may also be made to diagrams 5 and 15 of Swan and Morton's
'* Hydraulic Diagrams."
The Limitations of Kutter's Formula. — Being essentially an enipnical
pnnula, ba^ed upon actual gagingj?* it is of importance to remember the
lita within which observations have been made and further to re-
[lejnber that while velocity varies approximately a*s the .scjuare root of
bo hca4i tmder velocities corresponding to t lie ordinary conditions of flow,
i varies mure nearly directly as the head under extremely low velocities.
jflthtn llie ordinary velocity limits of from 1 to 6 ft., the formula finds
lis best application. It is fairly reliable up to 10 ft, per second velocity.

eTO'ff*-^

100

AMERICAN SEWERAGE PRACTICE

For special cascs^ which may be outside of the range of the formula such
as 20 ft per second or higher velocity, the engineer should nmkc reference
to the orip^inal data, published in Hering and Trautwine's tran^^lation of
Ganguillet and Kuttcr^s work, and that of other writers upon fiydrauhr^
since that time.

Hughes? and l^afford {'* Hydraulics/' p, 343) have summed up the
application of thia formula in an excellent manner as follows:

Coefficient, N

IS ^o 3.0

ooop^ o q p

00609 000
Kutter^ Coefficient, n
Fio, 32.

JL ma ![(» IT 7

5ozin*s Numerals for R9u3Hne»C0te9orie»,

Fto. S3.

Fig, 32. — Relation between Ivutter'a n and correspond itig slopes autt
velocities,

Fia. 33. — Relation between Basin's N and corresponding 8l'»p«'»* 'ma
yelocitiea.

^* There in a wide range in the magnitude of the streams on which tht«
formula is baaed (from hydraulic radii of 0.28 to 74.4 ft.); but a study oi
the data on which the formula is based, as given tn the authors' book, b«*
led to the following concluaionB!

That, for hyilrauUc radii greater than 10 ft.j or velocities higher th*n ^O
ft. per second, or slopes flatter than 1 in 10,(X>0, th« formula should l*c iiBod
with great caution. For hvdrfiuhr rri<!ii t^rf^ntf^r thrtn !?0 ff , or v**UH''iti<*
higher than 20 ft. r*er ' ^

That* considering 1 h •^

is baJN)d, results should not be expcaeteci to be consistetitiy aecur
i about 5j

IfYDRAVUCS OF SEWERS

101

lt« for any slope steeper than 0.001 the values of c computed for «•

lOOI may be used with errors less than the probable error in the ordinary

f of Kutter^s formula.

That between slopes of O.OQI and 0.004 the maximum variation (at the

extreme values of n and r) in r is about 4 per cent.; for such values as fall

within the range of ordinary practice the maximum variation is hut 2 per

cent.

That between slopes of 0.0004 and 0.0OO2 the maximum variation is
about 5 per cujit., but lor such values as fall within the range of ordinary
praf!t}ce the maximum is less than 3 per cent.

That for higher values of a tho divergence in the valuei? of c increases; but
the occasions when slopes flattcsr than 0.0OO4 are to be considered in design
arc not common, and when they do occur they are usually for structures of
«uch high cliaracter that they warrant special study and some basis in addi-
tion to a general empirical eo^^fficient. And considering that a degree of
RKTision of 0,001 is rarely exceeded in leveling for ordinary construction
rk> and that in picking out the value of n, a variation of 0.001 for small
Talues of n and r may change the value of c as much as 17 per cent., and for
moderate values as much as 5 to 8 per cent., it should be obvnous that hair-
splitting calculations with the Kutter formula are a needless waste of tiroe^
pro«iucing merely mechanical accuracy instead of a high degree of precision."

Effect of Ice. — The effect of an ice-sheet upon a canal, in reducing the
Bbw, is of importance as it increa-se<s the area producing frietional re-
Bptance to flow. This is indicated clearly by Fig, 17, showing the
HitHbutioQ of velocity in a vertical section of a flowing stream.
■ For a very interesting *'Deterraination of Stream Flow during the
^■oaen SeatJKon '' by H. K. Barrows and Robert E- Horton, reference may
^m had to Water Supply and Irrigation Paper No. 187 (Series M, General
TOJ'fi^^Kr^pliJf^ Investigations 19, published in 1907 by the U- S. Geolog-
ical Survey) in which this subject is fully discussed m the light of a
Urge number of actual observations and records.

HAZEN AND WILLIAMS' FORMULA

Of late years, several exponential formulas for the flow of water in
pipes have been developed. Of these the most important is that de-
■tfoped by Allen Hazen and Gardner S. Williams, which agrees closely
^Kih observed results and has the great merit that it can be applied with
Hfiility through the special slide rule designed and graduated for the
TOluUon of problems by it. Tables have also been prepared covering
iU application. Inasmuch as careful comparison of this formula has
m ma^lr with the better known Kutter 's formula, and as the use of the
Je-rulois not only convenient but effects a v^ery considerable saving in
ae in making many hydraulic computations, this formula is of particu-
im port an PC. While this formula has had application most often
pipes discharging under pres^urei it may also be used in sewer com-
ktatiotts.

^^

102 AMERICAN SEWERAGE PRACTICE

in which v== velocity, in feet per second
c » coefficient of roughness
r = hydraulic mean radius
« = slope

The authors say of it,

" The exponents in the formula used were selected as representing as nearly
as possible average conditions, as deduced from the best available records of
experiments upon the flow of water in such pipes and channels as most fre-
quently occur in water- works practice. The last term, 0.001"^*^, is a
constant, and is introduced simply to equalize the value of c with the value
in the Chezy formula, and other exponential formulas which may be used at
a slope of 0.001 instead of at a slope of 1." (Hazen & Williams^" Hydraulic
Tables," pp. 1 and 2.)

This formula may also be written

i/,=3.02i2i -,77;;7-7=3.02i2i^,,,;„,^,,,,„^

in which i// = friction head, in feet

V = velocity, in feet per second

c = coefficient of roughness

D = internal diameter of pipe, in feet

With regard to the coefficients to be used in this formula in general
design, Hazen and Williams suggest the following values for c:
140 for new cast-iron pipe when very straight and smooth;
130 for new cast-iron pipe under ordinary conditions;
100 for old cast-iron pipe under ordinary conditions; this value
to be used for ordinary computations anticipating future
conditions;

110 for new riveted steel pipe;
96 for steel pipe under future conditions;

140 for new lead, brass, tin or glass pipe with very smooth surface,

130 to 120 ditto, when old;

120 for smooth wooden pipe or wooden stave pipe;

140 for the masonry conduits of concrete or plaster with very

smooth surfaces and when clean;
130 ditto, after a moderate time when slime-covered;
120 ditto, under ordinary conditions;

110 for cement-lined pipe (Mctcalf);
100 for brick sewers in good condition;

HYDRAULICS OF SEWERS

103

110 for vitrLEed pipe aewers in good condition;

Thr iliizen and Williams formula reduced to the following forms for

tfpven values of c
when f -100, r- 131.8 r^-^h^-^ =55,0 rfO-63^0'^*
when c:= WK r- 145.0 r" ''^^^^^^-SO.S tfi-^'^s^'^
K when r = 120, v - 158/2 r^ ^^V'^'^ - m,Q tfi^h^^

■ when c - 130, V - 171,4 r" <^V'^* -71.6 (fi^^h^-^

■ when c = 140, r = 184.6 r^-^s^-^^ =77.1 d^-^h^^

. 4«lyM

Pkrtent.

I

Vtttwesof c,

Oiagnim A.

Fkw of Water in Pipe*,

Ctrrufkondmoi Valuer of ccni m

Ipi Hai«D-Wi)Uam» formula

tttrf

' : r r V ■

rpTPs

'T

Hd-h- H/i^

^^—

g

Trtl

t : 1 1 r

>^

1 ISl J I Sf Mm. its'

IllttI

lima

E£*

!SS!^59

r.v.f y|<:w :i^

»«0

■f"

-rt

"t

-ru

Kfiir

-;

! Nl

gr t .

'LVi

IjVJdl

V

^^

^

3f **

^

n

r

r^..

""l

i!^f

1

'i^

W^

^

fe.

i''

'\Wy

f

r

70

t'

\

ro

Rote of Vangtion of Certain Factors
tn Maicn-Witllamsformuta.

- i — lickUuns between factors in Uazen-Williarus formula.

wbt»nr= 90.8- /// =0,000f300 t>
1**100. ///^O 000598 e;

c=l04 ft^ /// =0.000550 P
c=ll0 ///=0 000501 t>

c*110H- A//=O0OO50Op

II tin j^

It till I

n iiti t

• l/D*

It iiti ^

ti.tiu t

f/D*

11 iiii £

C*llfl 6- /// ^0.000450 t^ • 'f//>*

ii.iiii £
c-120 ///^O 0(X>426u •///>•

II lilt f
c*12^1 2 ///-0.000400P • i/D*

f*i:ui ///=0 000368 «/• !/£>•

littn 2

r-un /// -0 ooa32l (? • ///>•
1^ rttio btitwoen the value of c and of m in the Uazen-WUtiama

104

AMEBIC AN SEWERAGE PRACTICE

PUO oui^

l^^tiUJi^t^

|»yO)9^ iid ^#i ii\ A4)iopyv

»«4LiniiM T^i7 J MoHi^c) .L

\n

!«l

O o S

C3 O ^^ O ^

S » t ^ £ e .

HYDRAULICS OF SEWERS

105

formula is shown in Diagrams A and I, Fig. 34. Figs. 35 and 36
have been plotted for c equal to 100 and 130 respectively and Fig. 37
gives a comparison of the Hazen and Williams formula with others
and with experimental results.

The relation between the value of c in the Hazen and Williams formula
and the c of the Chezy formula may be found by equating the value of
i in these two formulas, which gives the equation

(Chezy) = 1.1506 cOW59y0.074i/2)ao833

CHAPTER III

VELOCITIES Ain> GRADES

The ratio of the mean to maximuni velocity varies with the value of
c and with the character of the stream measured. Bazin gives the
values recorded in Table 16.

Table 16. — Values op the Ratio op the Mean to the
Maximum Velocity

To be used in obtaining mean vclocitiea from maximum velocities when the value of tbt
coefficient c in the formula vcy/r »\a given. (Hering and Trautwine'a Tranalation of
Ganguillet and Kutter'a "Flow of Water.")

c

v: v„

C

v:v^

C

v:v^

C

v:v^

2

0.06

46

0.64

90

0.78

~IU~

0.84

4

0.13

48

0.65

92

0.78

136

0.84

6

0.19

50

0.66

94

0.79

138

0.84

8

0.24

62

0.67

96

0.79

140

0.84

10

0.29

54

0.68

98

0.79

142

0.85

12

0.32

56

0.69

100

0.80

144

0.85

14

0.36

58

0.69

102

0.80

146

0.85

16

0.39

60

0.70

104

0.80

148

0.85

18

0.42

62

0.71

106

0.81

150

. 0.86

20

0.44

64

0.72

108

0.81

155

0.86

22

0.46

66

0.72

110

0.81

160

0.86

24

0.48

68

0.73

112

0.81

165

0.87

26

0.50

70

0.73

114

0.82

170

0.87

28

0.52

72

0.74

116

0.82

175

0.88

30

0.54

74

0.74

118

0.82

180

0.88

32

0.56

76

0.75

120

0.82

185

0.88

34

0.57

78

0.75

122

0.83

190

0.88

36

0.59

80

0.76

124

0.83

195

0.89

38

0.60

82

0.76

126

0.83

200

0.89

40

0.61

84

0.77

128

0.83

. . .

42

0.62

86

0.77

130

0.83

. . .

. . . ■

44

0.63

88

0.77

132

0.84

• / •

....

The ratio of the mean to the maximum surf ace velocity at a number

of places is givon in Table 18, from Hering & Trautwine'a transla-
tion of Ganguillet & Kutter's "Flow of Water."

106

VELOCITIES AND GRADES

107

Hi

.a

o t^ <o t^
CO W3 o r^

o o o o

to O CO 00

"^ « S r^

o o o o

^^ CO CO ^^ oc
-^ W3 « r^ r^

o o o o o

»0 Oi ^ Oi t^ CO 00
<^ <^ &0 U3 ;0 t« t^

o o o o o o o

C0^»O00»O^iC00
<^kOU3iOOt^t^t«

dddddddd

OO^OO^OOCOOOi

dGci<6<6<6<6(6

oooooooo

So^ lo t^ c^ fo cc a>
o ;o CO t« t« t^ t^

oooooooo

S5:; S ^ if? 9? ^ 9
CO CO t>> t^ t>> t>> 00

t^OMcot^OiO^
cot^t^t^t«t«oox

OcOtOCOOO^^

t^t^t^t^t^oooooo

OOOOOOOO

piocor^wo^c^ci
t>.t>.t^t^t>.oooooo«

WSOOOiO^C^COCOCO

r^r^t^oooo«ooooo6

ooooooooo

'^©COCO'^'^'^'^f'^'^

t«t^ooo6xxoooooooo
oodoooddoo

000000x00x06060000

^W'«f«OXOOo88

108

AMERICAN SEWEHAOE PRACTICE

(?)0.d2 1

0 78 1

0 80 J

0 82 ■

Q 82 ■

0 82 1

0,8a ^

O-M

0 85

0.79 to 0.82

0 78 too 80

0 66 loO 84

0 83 toO 85

0 79 100 80

Table 18.— Ratio of Mean to Maxtmitm Suhfaci: Velocities

Belfp'&ndi for the Seine

Destrem^ for the Neva

Baumgiirtiier, for the Garonne

De Prony, for small wooden channela. .

Boileau, for canals

Cunningham, for the Solani Aqueduct,
BaziUp for smaU channeli?

Swiss Engineers

Brunnjngs, for rivers.

Humphreys & Abbot, for the Misais^^rppi (mpan)
Humphreys & Abbot, for the Ohio. .

Humphrej's Ac Abbot* for the Yazoo

Humphreys & Abbot, for the Bayou Plaquemine.
Humphreys & Abbot, for the Bayou La Fourche

Ratio of the Heap to Center Velocity in Pipes. — In a most valuable
article upon '* Experiments upon Flow of Water in Pipes" by Williams,
Hubbell, and Fenkell (Trans. Am, Soc. C. E., April, 1002) the results (
elaborate testa of the relation of the mean velocity to that at the cent
of a pipe are given, and similar data to those given by the authors were
submitted in the discussion which followed the paper. The experiments
cover a considerable range of pipes, 2-in, brass tubing, cast-iron pipes of
diameters up to 30 in., circular conduits up to 8.75 ft. in diameter, and
two rectangular conduits approximately 20X31 in* in section, and indi-
cate that the mean velocity of flow is from 0,80 to 0.85 of the renter
velocity, ^ * "verage value foimd by W^illiams for cart-iron pipes up to
30 in. in diameter being approximately 0.84, Tlie mean velocity T^*as
found to lie at about three-quarters of the radius of the pipe from its
center anfl the velocity at the perimeter of the pipe was found to be
approximately one-half of the maximum velocity.

TRANSPORTING POWER OF WATER

The transporting capacity of water, due to its velocity, pi. *iys ;in in
portant part in the disposal of sewage by dilution and diffusion and i
preventing clogging of the sewers and local fonnation of sludge bank
is a result of the settling out of the hea,vjer particles of the ttei^age.
prevention of clogging of sewere is discussed hereafter undej* Minimu
Grades and Velociliea fur Sewers. It hi '
ing capacity of water varies a^ the «iM

the velocity lie doubled t)tc t ry b< i»4 time! as \

Theref"^** '^'^ rnOu*'ncc '!*^i''' - r- !xH.;t%r -** ^rir m*i

immi}«ii iltsinnu

VEWCITIES AND GRADES

100

at deposition of particles which had hevn carried along
radtly Ijy the curreut of greater velocity. The form and adhej^ive
jality of the particles also plays a part in the formation of sludge banks.
Much of the information relating to the transporting capacity of
; id almost valueleiis, owing to the lack of exact knowledge of the
aty near the bottom of the stream, which, together with the char-
.he material composing the bottom and the depth and hence
of water upon it, are the most important elements in the
1% of erosive action. Freeman has called pointed attention to these
in bis Charles River Dam report, and has cited the opinion of the
veteran engineer, Hiram F, Mills, in regard to the misuse of the observ^a-
tiotm of Dubuat, who made experiments in 1780 upon the capacity of a
fitra&m in a wooden trough to move particles on its bottom. All of these
obsen'siioDS failed to take into account the varying velocities of flow
in fir ' td ftection. Many engineers who have made use of the

wssu! n>c experiments have failed to recognize this fact, as well as

effect of the character of the material, the coating of sHme or col-
1 surface which forms upon the bottom and the effect of the pressure
1 the material, due to the depth of water. Freeman quotes obser-
i made by Mills and Hale on the Essex Company *s canal on the
' River in Lawrence, which were nmde with sufficient care to be
al| using a current meter to determine the distribution of
itiofl.
• Ai Stuiiim No. I, middle of west chord of Everett Railroad bridge:

^ bed conii)lctely and smoothly covered with fine sand, as per
mccliiimcttl analysis is given in table following. Deposit 8
to 12 I ' Surface near the bottom marked with Ultl*' wnves of mud

^ higit. , ly rolled up t)y the more rapid velocity when emptying

m\. Side Ak»pea smooth and free of wave marks. Sand so soft and so
« f^'-' ^-..*'-f thai one*s fv«t atnk into it 3 in. while walking across, or, when
n iif a minute or two, the feet gradually sink into it about 8 to

III, 1 r.M ^an«l plainly is not being scoured^ although it is softer than any
lilt that I have seen uncovered at low tide on the chores of Boston harbor,
inqit perliap9 the ailty sludge in immediate proximity to certain sewers.

U

Maximum surface velocity in center found to

bo

•jf cent or section
M. from bottom

1.3 ft. per second.

1 0 ft. per second.
0 . 8 ft. per second*

"Thii flbowH that a particularly soft bottom was not eroded by a bottom
^v^ty tif ftbout 0.8 ft. per second « and that the condition was one thai
Uvfrnd Hepfwiita,

2, at upstream aide of Union *Street bridge:
►mtriince the mmn as at Station No, 1, except that surface of
Pl fiotj nf canal is ooverud by 4»and waves averaging about
- -.^-.ts traosvccrse to current, suggesting a rolling along of the

110

AMERICAN SEWERAGE PRACTICE

land grains which pcrhapa has been induced by the highor velocity frd
drawing off and refillinR the canal a few timea very recently, rather thun
the ordinary Bow« 1 find, on tramping back and forth over the silt, that]
15 much more firm than at Station No. 1.

Maximum siu-faoe velocity. , . . 1 .9 ft. per second.

Mean velocity of center section 15 ft, per second.

Velocity at 3 in. from bottom in middio. , . 1 .2 ft. per second,

"With these velocities silt of this qitality h deposited 12 in, deep, i
apparently is rolled into waves only by the recent drawing off of canatf aic
no sand waves are found more than half way up on the sloping aisles of C4itu
The indication is that a bottom velocity of 1.2 ft. per second favors dep
and not scour.

^'Station No. 3^ from same cross-section, but about three-quarters dista
up Flope from center toward north 4?ide and 6 or 8 ft. up from bottom lev^
where there were no sand waves:

"Deposit 8 in. deep, velocity at about 3 in. from bottom found to avera
0.9 ft. per second. Condition here is plainly one of deposit, and not of scoU

"Stalion No. 4, upstream side of Pemberton bridge:

"Upstream from this point the bottom and berms of canal are substan-
tially 8coiU"e<l clean, but a short distance downstream from this point on the
northerly edge of berrn a deposit bepjina, and, going downstream* quickly
spreads out to 5 ft. in wiilth opposite to the penstocks of the Pemberton
Mills, and below this gradually widens out, until at Union Street it covert
the entire b«id of the canal from north side over to foot of south slope.

*'At Pemberton Bridge^ where entire be<l is scoured cle*i.n, there is some
irregularity found in the distribution of velocity » but r}m L'fiiieral average of
a dozen or twenty observations ran about as follow^

Mean velocity of entire cross-section. ....
Velocity *i in. from bottom at mid-channel

At in ft. from north side.

In corner next north wall (at deposit )

"The observations at this point sliow that a velocity of 1.5 ft. per •<
prevents deposit or produces scour or a rolling along that keeps the bott
clean.

**In general, these north canal observations show that the velocity ne
8ar>' to prevent depowit or necessary to produce scour of grains of hue rW
silt and sand of sijsea shown by followitig analysis (Table 19), and formi|
part of a mass deposited only less than two months before and not compact^
by long standing, was not far from 1.3 to 1.5 ft, per seeon*!, I his velod
being measured at a distance of from 3 In. to 6 in. from bottom.

**These observations thoroughly disprove the oft-quoted, ccntl
OrudCt unr*_diable observations of Dubuat.

**The boiling and eddying of n rurrcnt ha?; mtich to do with tti^ powftf 1
transport material in I ha^ ripr

it^ Htraightin s- ufn! n rTdUt any ^, „ , av4n

aniH^ than i^ 1 tibouM mtk^ Um nM^idi*

of g«ncr'*l

2,5 ft. per secomi,
1 0 ft, per second.
I 5 ft. per second.
0- 9 fu per aocond.

VELOCITIES AND GRADES

111

^XabIpS 10- — MBCMANirAL Amaltsis of Average Samples or Sand

^AiierrLLY CoLLErTED FROM WITmN OnE-QUAKTER TO OnE-HALF
IlfClI OF SrRFAt'E AT AbOVE STATIONS, ANALYZED AT La WHENCE

Exi>EmMENT Station, Mabsachusetts State Board of

Health

I From J. R, Ffpcmnn'* Report on Chnirl*»« River Dnm, 1003, p, 4151

^^^B X tirnhiir uf «f»Rtplf<

No. I

No. 2

No. 3

^^^^E oust, fmor thfiD (diam. in millimetemi

0.12

0.15

0.04

^^^^htlty coeflident ...«,..,........,,

I 40

1.70

3.00

^^^HkAD 2 (H mm (per oeat. by weight) .

im.oo

100-00

HW.OO

^^^KliAn 0 93 mm. fpcr «f>nt by wrigbt)

09 00

nu.flo

100.00

^^^^Bbjin <KIH mm. Cl'^'r rcuT by weight) .

9S.00

07.80

00 00

^^^^^^1^310 Rim CrM^r cmti. by weiicht)

»5.iiO

W3.4U

©7.80

^^^^^^Hl$2 mfn, Ci>«»r c<»nt by wciebO

56.10

33 JO

SO. 20 ,

^^^^^^^K]0& mm. (iybT c«jit, by weight) ,

4.:jo

0.00

32.40

^^^^^^sn Ui^ mm, ipet e«rii. by wciifbt) , .

19-10

^^^^Baa0O4 mm tppt et*ai. by wc^igbl)

0 00

^^^^^^■moi mm. (t^^r cent, by weifcht) ,

o.iai

R — Gancuiuxt axd Kutter upon the Transporting Power
OF Water

^IlirltiC A Tr^atirinn's Truiisbttion of Gnniruillet and Kuttpr*e "Flow <^>f Wnter,'* p. 124)

Ci4 3 lives tb« vf^iocity at xhf bottom; Col. 3. the mean %'clucity as figurvil by Baain't

iiul«, rari-f tO.9 V ft^. in KngHsh measure, or an average value of ?"*1.31 t*; Cot.

I rvMiuint the m&Kimum •urfarc velocity am figured by Basin's formula » v— cm ax "^25.4-

SS iu EnKllah fn«a««lf«, or m menu value of T^-Q.gS rmnx

I ...„.™^„.™..

Bottom
velocity^

ft. per icc.

.. Maximum

(Upcr.oc. "'•-"•
JL . ft, per |rt^c.

**t»4 lK» fif- ' ' ^*'*!tt. specific gra^nty =« i.oa . . .
Cl^^lj^jij ,,i\ _ . .,

(2V
0.25
0.35
0.50
0.60
0.70
1.07
2.00
2.13

a. 00

3.23
4.00

a. 00

«.00
10.00

{3)
0.33

o,4e

O.AO
0.70
0.02
1.40
2,03
2.70
3.03
4 23
5.24
6.55
7 SO
13 12

(4)
0 40
0 55
0 7«
0.05
MO
l.«9
3,15
3.3«
4.73
5.00
6,:W
7.80
U 43
15.75

C«tt , -3.30

P*^^' f,blnitoarii, ...*,,.,

BAbj^i ... . .

Ito found the ftillowmg velocities in feet per second were
lo muve the bodies de»rril>ed: fine clay, 0.25; sand, 0.50;
»siod, 0.65; fine gravel, IM; pebbles 1 in. diameter^ 2.00; stones
B, 3,00.

^11 nho^fd by QXperiniontti made for the British Metropolitan
ion timl the specific Kntvity has a marked effect upon
-ftrv to move bodies, as given in Table 21.

112

AMERICAN SEWERAGE PRACTICE

Table 21. — Effect of Specific Gravity on Susceptibility to
Velocity of Water

(Horins and Traulwine's Translation Ganfcuillct and Kuttor'a "Flow of Water," p. 125)

Nature of bodies Specific gravity

Velocity in feet per
second

Coal

1.26

1.25 to 1.50
1.50 to 1.75
1.75to2.00

2.00to2.25
2.25to2.50
2.50 to 2. 75

Coal

1.33
2.00
2.05
2.17
2.12
2.66
2.18
2.17
2.66
3.00

Brickbat

Piece of chalk

Oolite stone

Brickbat

Piece of granite

Brickbat

Piece of chalk

Piece of flint

Piece of limestone

Note that in both of the above quotations there is no discrimination
between surface, mean,, or bottom velocities.

The Metropolitan Sewerage Commission of New York, 1910, assuin®^
the velocities given in Table 22 to be necessary to move solid particlcB.

Table 22. — Currents Necessary to Move Solids

(Metropolitan Sewerage Commission, New York)

Kind of material

Velocity required to move oD
bottom

Feet per second |

Fine clay and silt

Fine sand

Pebbles half inch in diameter.
Pebbles 1 in. in diameter

Miles per hou£^
about i
about \
about }
about 1\

In general it is found that a mean velocity of 1 ft. i)er second, or thc?t^
abouts, is sufficient to prevent serious deposition of sewage upon ti^*^
flats, if the sewage is rea.sonably comminuted.

The interesting exi)orinient8 both of Professors Adeney and Lettfi of *** -
Royal Commission, and Clark of the Massachusetts State Board ^
Health (the latter made in connection with Freeman's Report upon *'** '
Charles River Dam) conclusively point to the fact that the polluti^^
organic matter is precipitated very nuirh more rapidlj' in salt wa*^*^
than in fresh. The danj^(T of formation of sludge i)ank8 from the d*^
charge of a given quantity of sewage into a Ixuly of salt water, is great^^
therefore than in the case of a like body of fresh water. This is not *
phenomenon depending upon tlie transporting power of flowing wateO
however, although it might be confused with it.

VELOCITIES AND GRADES

113

EROSION OF SEWER DIVERTS

Tlio orosivo cflFect of so wage upon sewer invert^} of different kinds u
^uaiiiipcirtttiit in the case of the separate ayistem unlens there bo chance
for the entry of f^and, gravel or other silieious material. In the combined
»y«iteiti, however, which has to deal with jsiliciouii material as well as with
un water and sewage, the effect may be important. The rapidity of
tliie erosive action will depend not only upon the velocity of flow, but also
lupon the character of the material transported, arenaceous material
[being much more des^tnictive in its influence than argillaceous or lime-
etcne, on account of its greater hardness. Vitrified sewer pipe is re-
eiatant to erosion and has been laid successfully upon very steep grades.
I In large combined sewers, it has generally been customary to line
Iconcrote or brick sewers, in the invert at least, with vitrified brick,
[vrhere the velocity of flow is in excess of 8 ft, per second, although sonie
rngincers have used as low a limit as 4 ft. per second. Wrcmght-iron or
plecl Inverts have been used in some very steep sewer outfalls; in others^
jfpssed channel has been made in the main sewer, lined with split
vitrified brick or steel, large enough to carr>^ the dry weather flow,
Ihe remaijider of the invert being formed in concrete or lined with vit-
brick so that in case of need of repairs, it should be possible to get
into the sewer during the dry weather season to make the repairs with-
out interruption of service.

It seems likely, in view of the accumulating favorable experience with
concrete inverts, in irrigation as well as sew^erage works, that concrete
inverts may be used without a lining of vitrified brick for higher veloci-
Jtiea than heretofore customary, except in those cases where the sewage
i exceedingly stale, or impregnated with deleterious chemical8,the sewer
ftiily ventilated, and the materials transported very hard in character.
The Metropolitan Sewerage Commission of New York reported in
1910. with reference to erosion in the outlets of the sewers inspected, that
few cases were found where the bricks of the inverts w^ere actually w^om
iway* In a few places in the upper west side of Manhattan, the upstream
Iges of the bricks were rounded o0 as a result of the high velocity of
pwage. In a large number of the sewers the mortar was w^om from the
joints in the brickwork of the invert. Sometimes the mortar has been
I'nm away only to a slight depth while at otlier places it has been cut
crut by the sewage to the full depth of the brick.
In combined sewers at St. Louis, with grades ranging from 0.2 to 2
er cent., averaging about 0.5 per cent, for sewers more than 5 ft. in
Jiameter, and about 1 per cent, for those of smaller sections, vitrified
[rlay pip<w were stated by E. A. Hermann, in Eng, News, Feb. 4, 1904, to
liOff no appreciable wear after about 35 years use, vitrified brick in-
to ahow no appreciable w^ear after about 12 years, and inverts of

114

AMBRICAN^ SEWERAGE PRACTICE

ordiDAfy fiewer brick to abow some wear after about 3 yeans seri'ice a
from 2 to 4 in. wear after a use of 30 years.

MINDtfTJM GRADES AND VELOCITIES

The transportlDg capacity of water is important on account of it^
bearing upon the |>o&stble clogging of sewers. The actual conditionaj
flow in the sewers must abo be clearly borne in mind.

As wiU appear in the diagrams showing the hytlraulic elements]
Tarioua sewer sections, the velocity of flow in any sewer laid upon a gii
grade varies markedly with the depth of sewage flowing. Ob^iou
the quantity flowing also varies greatly, at diiferent hours of the day J
diseussted in the chapter on the quantity and variation in flow of ti^wu
At times of low flow of sewage^ the velocity will be go low that the str
will be able to transport only the finely comminuted su^spcnded matt
the paper, street waahin^ and other foreign matter contained in
water will temporarily find lodgment upon the bottom and >'
sewer. If the foreign matter is ^uflSeient in amount to cbm>i _^
pooling of the sewage behin<l the obstruction will result until the volu
and pressure of liquid are sufficient to break through the obstruction ai
develop a velocity which will again pick up the arrested material and
transport it. Owing to the grease contained in the sewage and the ca
dittona of flow, however, some of the material may not be picked
again at the same velocity as that at which it was transported when iij
suspended condition, and obstructions are thus fomied and gradually bu
up to |i point where sufficient velocity is developed to maintain a chanj^
through the sewer.

From the point of view of operation, it is important that the minimij
velocities assumed in the design of the sewer, when flowing one-h
two-thirds, or full, as the case may be, shall lie ad* quate to keep]
thoroughly flushed. In general, it has been found that a mean velo^

of 2-1/2 ft. per second will ordinarily prevent deposits in i
built upon the combined system and,

2 ft, \yQt second will ordinarily T»rin<»nt ilr'mi^its in s/'u»>i^ t»
upon the separate system.

It is desirable, however, that a moan velocity of 3 ft per aecood* j
more, shall be obtainetl where po- ' ' I thb minimum litnit sh<

not be lowered in the r.:ise of inver i is untler any ordinsrj-

tions. While lower ndnimum \i^ociUt»? have l>een Uijed in
places, they have often been accompanied with more or Ics?* ^%
remoWng sediment by wliich the sewers might in ibne become i
and such work i- ' '■'

second have U-

VELOCITIES AND GRADES

115

>n the separate system, but they are undesirable and are likely to
lead to greater cost in maintenance.

In general^ the miiiiioum grades given in Table 23 for small pipe
ftcwcw laid upon the separate system have been found safe though
fiteeper grades are always desirable. Tliese grades are the least ordi-
narily pennitted by the New Jersey State Board of Health, In its 1913
r^golatiana go^'erning the submission of designs, it stated:

* The Bewers should have a capacity when flowing half foil stifficient to carry
riwieu Ihe future avc^rage flow 25 years hence, plus a sufficient allowance
I f Of pCMind- water infiltration. When grades lower than those given are used,

ID nplntiation njid rensoDB for the use of guch grades should be included

h ibt cfiginecr's report/'

Tabi^ 23.— MiNiMtrM

Grades in Separate Sewerb; fob

2-FT. Velocities

Diimieter, inches

I Minimum fall in feet per 100 ft. |

1 '

L2

r 6

0,6

8

0,4

10

0.29

12

0.22

15

0.15

IS

0.12

20

0.10

24

0.08

I^Thfl %'tilocity of flow and capacities of the sewers are determined in
ittan, Brooklyn, Tlie Bronx, Queens, Richmond, Newark, the
t Jemey Joint Outlet Sewer, Elizabeth, Jersey City and Hackensack
"J lh« usr of Kuttcr's formula. In Kutter's formula the value of n,
takea Into account the roughness of the interior surface of the
f itt jiajitmed for pipe sewers to be, in all the cities, 0.013; for brick
' ^veDi in Manhattan, Richmond and Jersey City it is taken a^ 0.013
•»d in Bnxiklyu and Tlie Bronx and Queens, Richmond, Newark and
8»clU!iwack at 0,015. For concrete in Manhattan 0.011 is used; in
B^klyn, Queens, Newark, 0.015; in The Bronx, 0.014, arid in Rich-
^^d, O.on for smooth fiiiii^hed concrete, (Report of Metropolitan
8*nrige CommiBfiion of New York, 1910, p. 90.)

hnhair hiui tj«ctl jsuecessfully minimum velocities of 2.3 ft. per second
« Biaioiiry-itood open channels built by him in Ccrmany, but theee
rtinnplfl carry the effluent from the Imhoff or Emscher tanks and not
wniwaeiraic^ of the communities through which they pa^s.

Tb^ main int<!rc4*ptinK -tewer at Columbus, Ohio, 2| to 6 ft. in diame-
^ kid VI ft. of 0 fil ft , p^r 1000 for the ifmall section to 1 .94 ft,

%a 16-21 ri. Riving vclijcitieii from a minimum of 1.72 ft. to a

116

AMERICAN SEWERAGE PRACTICE

maximum of 3.6 ft. per second (assuming the sewer to flow full and n to
equal 0.015), has given considerable trouble from the collection of large
quantities of sediment. The cost of removing this sediment is reported
to have been approximately $1.78 per cubic yard. It should be stated,
however, that an unusually large amount of sediment entered this
interceptor on account of the defective design of the connections of the
lateral sewers with it, and the discharge of tar into it from a gas plant
(Trans. Am. Soc. C, E., vol. 67, pp. 326-327, 433-434.)

Part of the Boston Main Drainage Works consists of a tunnel 7.5
ft. in internal diameter and 7 166 ft. long. The ordinary velocity throu^
this tunnel at the inception of the works was about 1 ft. per second. To
ascertain the extent of deposits under these conditions, water vas
pumped in at one end and the difference in level at the two ends was
noted for the purpose of figuring the value of c in v^c\/r8. It was
assumed that when this value approximated 137 it would indicate that
there were no deposits. The results of these experiments are given in
Table 24. These figures indicate that deposits occurred with a veloc-
ity of approximately 1 ft. per second and did not occur with a velocity
of approximately 4 ft. per second. (Boston Main Drainage Report,
1885.)

Table 24. — Experiments at Boston to DnTERMiNB Velocities at
WHICH Deposits Occur

No. of experi-
ment

Mean velocity,
ft. por second

Value of c in »•»

Liquid flowing

1

0.929

79.95

Sewage

2

0.998

82.00

Sewage

3

3.988

129.05

20 per cent, to 25 per cent, tew-
agc, 75 per cent, to 80 per cent,
salt water.

4

0.905

109.66

vSewage

5

3.929

120.67

20 per cent, to 25 per cent, tew
age. 75 per cent, to 80 per cent,
salt water.

6

3.897

146.31

Ditto

7

• 4 . 0('>2

146.64

Ditto

H. P. Eddy, Jour. Assoc. Eng. Soc.j 1904, p. 235, gives his observatioDB
upon certain sewers in Worcester, Mass., in Table 25.

The Metropolitan Sewerage Commission of New York, in its sixth
Preliminary Report, 1913, fixed from 2 to 5 ft. per second as a suitable
range of velocities to prevent deposit from screened sewage from which
the grit has first been removed, in a proposed siphon 2300 ft. long from
8 to 9 ft. in diameter, to be laid 110 ft. below the surface of mean low
water to carry the sewage (99,000,000 gal. a day in 1915) from Manhat-
tan Island to Brooklyn beneath the lower East River.

VELOCITIES AND GHADES

Tait^ 25. — Obskrvattons at Wohcester of Velocitucs at
Deposits do axd do not Occur

117

WHtCB

^

*fiiwi

fiiiid of MW«r

iovbcif

Appro*, mwiu
velocity, ft.
per M?eond

Sh«p«

Hfimarks upoa
d^i>oiiit

Ki.^^^

Btomi . , . .

24x34)

2.oa

Em

Deposit ocrun.

Hk:

Btomi

18

1 47

Eir« ..

Deposit oecum.

B%QTm

18

1.46

Em...

Deposit oceurw.

B.

8tt»rm . .

18

1.17

EKg,...

Deposit ocoura.

tniik

Storm

18

2.SA

Em...

Deposit occum.

Fiak

8MM11I . .

IS

i.ia

Em. ..

Dc^poait occur*.

^H

riik...,

Storm .

IS

2.U

Em...-

Deposit occuri.

■

llliUai>il

fitorm . *.

18

8.74

Em..^

No deposit.

iGshUnd

Storm . *

18

3.02

Egjt...-

Ko deposit.

■

HliMkrid

Storm . , . .

12

2.20

Ruund..

No deposit.

■

fee

Cnmhinrflr - .

22x33

l.dO

Em....

Deposit occun.

■

K

<'...'..l.| (',,.

18

1-94

Em-,..

No deposit..

^ -

f '-trtNiri'-*J, ..

18

2.2ft

Em. . . .

No deposit.

^H

Bk

Cambinwd...

18

1.72

Em....

No deposit.

■

■■l^

Cf>tnhuied.>.

18

2.01

Em...

No deposit.

Combififd,

15

, 2.56

Egg..,,

No d©po«il.

■

■ort^.. ; :::

Combined...

15

1.64

E8K...

No deposit .

»*iik

Combined,,.

12

4-63

Hound..

No deposit.

■

«<«r4h

ComhlnH

12

6.97

TUmnd .

Nn deposit 1

Tka Fink nod Hifcblii.nd vtrcet »cweni form a vioicle Una, beicmoinn witb n 12-iu. rouud
•■■tiun Tbo figurr* b«*gia at the bottom and shouid btj rend upvvTvrd. There waa no
^f^nkAfi tmitJ ihtf velocity dropped to 2.14 ft. per iieeoDiJ. The reason that trouble l»
m^timHism4 wbf»rf» the velodty should tbeoretienlly b« 2.86 fl. per sc(;ond probably lies
(bill' on canh aid** of it. In the coAe of th« North street M>wer» ho trouble

^^i; cii the lower end is reached, where for about 4MJ ft. the vcloeity fftlls

^•IV™ ri. jM r ixccmd Thi« is not so low oa the Telocitiea nt a<'veral other pliices, but
Mbttf th« l»tt«r in preceded by at loaat one section which has a good velocity.

Ill St lAmiA sewer designing under W. W. Homer {Eng, Newa^ Sept.
$» 1812) the curves were sometimes compensated by the Markmann
fcrmulu (Eng. News, Sept. 29, 1910). This formula is:

8,'-8+v'/2gT*

(1)

^^ 5, is the grade or fall per foot on the curve, equivalent to a grade
^ "■ ' " the velocity due to the grade *S\ r the radius of the

^^ ; the aeceU^ration of gravity. In applying the formula

rt is :i , I ', tor the velocity to be known, and this can only be obtained
frimi iLu Uiui»hcd computalioDs* This involves a system of trials, and
^QMquonily the custom in St. Louis was to make the compensation
W^ Ti of the tangent grades a part of the records.

1»^* 1 by the method described in Chapter VIII

^ 1^ rtinoiT. and a preliminary grade was plotted. If the

^K^iini iji.ui r inve»tigatJou coosietted of a tangent of leuRth I and a
'WVe of length L, the actual grades would be S^c and SI and the total
^ in grade^ F^ would be

F^sjr^si m

118

AMERICAN SEWERAGE PRACTICE

In practice, a grade was assumed somewhat less than the preliminary
grade and from this and the required capacity tlie velocity was quickly
determined from diagrams. These values were substituted in Eq. 1 and
a value of Se obtained. The results were checked by substitution in Eq, 2.

Engineers* Opinions Regarding Minimum Grades. — The foliowing
opinions as to safe practice in selecting minimum grades were furnished,
in 1913, to the authors by the engineers whose names are given.

James N, Hazkhurst stated that his practice had been largely in
connection with sewer systems in the southeastern coast states, where
there is much silt and running sand, Minimimi grades were absolutely
necessary to accomplish an>i.hing and he generally used grades lower
than those recommended in text-books. The minimum grade for each
Biae of pipe sewer, which lie ordinarily permitted, was: 6-in. sewer,
0.33 per cent.; 8-in., 0.25; 10-in., 0.20; 12-in., 0J7; 15-in.,0,15; 18-in„
0J2; 20-in., 0.10; 24-in., 0.08. When sewers were properly constructed
he reported that ho knew of no trouble from deposits when the grades
were not lower than those stated. In Waycross, Ga., there were S-in.
pipe sewers on grades as flat as 0.24 per cent., which operated without giv-
ing trouble; a few grades which were as fiat as 0.10 per cent., however,
w^ere clogged from time to time and had to be roddcd out.

Charles B, Burdick stated that it was the practice of Alvord and Bur-
dick to secure grades that would give a velocity of 2 ft, per second in
separate sewers flowing full or half fiill, and to reduce the grade to li ft.
per second, if necessar}% Even on such grades they used flush tanks at
the summitsof the laterals, and if these velocities could not be obtained,
special flush tanks were usually installed. On combined sewers they
endeavored to secure 3 ft. velocity, but reduced it to 2 ft. if necessary.
They stated: ** It is our practice to got all the grade we can at reasonable
expense, and if it is itnpos«ible through phydcal conditions or cost to get
the grade desired, we usually install eome means for flushing, with the
idea of removing depo.sits. We have in several cases installed a specially
capacious flush tank at the head of a main where an unusually flat grade
is used» these especially flat grades coming more commonly on mabis
than laterals/*

George G, Earl stateil that the standard minimum grades for sewers in
New Orleans, given in Table 26, were occasionally exceeded, l>e-
oause it has been necessary in sonie cases to lay comtiderable 8-in. pipe
on grailes as low as 0.25 per cent. Tlie aim is to have a velocity of 2 ft.
per second in a half-full 8-in. pipe, and a slightly increahing
half -full sewers as the sixe increases. The sewers an? of terni
up to 30-in. diamet^. and either brick or concrete in larger sixee. Borne
of those over 30 in. in sixe are .semi-ellipticd in section, but on aecrii * '
constant leakage the volume of flow is sufficient at all times to i
circular sections fairly satisfactory.

In itMS drainage system at New Orleans, better bottom grades are

itaiaAUy obtained than in the sewers. The main drains have a V-shaped

_boltom, with the bottom slopes about 1:4; they are 4 to 25 ft. wide,

jpitli guod bottom gradients which give velocities of 5 to 10 ft. per second

r^iim ninning full. The laterals enter them at the top of the bottom

B, and thus have the maximum grade practicable. Mr. Earl stated

Imt thi* drainage system, particularly the terra-cotta pipe laterals from

Po to 30 in. in diameter, receive street washings and sweepings in dry

^atli«r when the flow is inadequate to remove them, and consequently

i good deal of flushing and cleaning is required on account of these dry-

|reath<ir accumulations.

Table 26. — MmiMCM Grades ow New Orleans Sewers

¥

1 Di^mrt^T.

Slope,

Diameter,

Slope,

DUmeter.

Slype*

iOf^hl^

per pcol.

per cent.

iDchess

pcT cent.

8

0,33

27

0.100

48

0.002

10

0.25

30

0.091

SI

0.069

13

0.21

33

0.0S3

M

0,056

1«

o,i6r

30

0.083

&7

0.063

t%

0.133

39

0.077

60

0.060

31

O/IU

42

0.071

03

0 050

a«

0 1(10

15

0.0<17

Gfl

0 060

(kor^ Ws Fuller stated that his drafting-room practice for separate
^wwer^ wa* basted on a 2-ft. velocity when half-full, with a coefficient
<rf roushjie^, w» of 0.013. This coefficient is also used for concrete
^^ in dianieter and over, and 0.015 is Ui*ed for brick sewers.

iUi ;40 to the expense of pumping where the grades tend to m^ke

*t \\»ZQSbtLry% the stlopesi giving the velocities mentioned are sometimes
HiiUeiied. This is done, however, only after a careful examination of
^fti ooudltiotiM on the ground, and Is not normal office practice. For
are, at Vinceuines, IncK, in a sewerage system dewigned two years
Mr* Fuller made use of grades of 3 ft. per thousand with H-in* pipe
*od hi jiome ca!«e« a grade of only 2.5 ft. per thousand was used* J. R,
Ml"' ' -^ ' rtod subsequently for Mr. Fuller that an examination

^ ! , N. J., sewerage system revealed a numljer of sewers

^^' 3ns, w*hich were apparently quite satisfactory. Six-inch

^* . iUj^ freely with grades as low as 3.5 ft. per thousand, and

Iktftwerc cikm» of I2-in. pipe with a grade of about 1 ft, per thousand,
■TiH ^ ^ I of 1 ft., li ft. and 2 ft. per thousand in satis-

'■' wcr^» other sections on this same system,

"'♦ re ftcweni with graiien apparently as low were partly clogged.

^1 . ^, : wtaltni that in the case of separate sewers he was of the
Qlriniim tliat the depositing velocities would not have appreciable sig-
Mfcwi^ ' ^ly evcr>' day there w^ore peri mis when the velocity

JW^i^ r second or more* He stated carefully to clients

120

AMERICAN SEWERAGE PRACTICE

that where the slopes of sewers, more than two or three bloclcs remo'
from flush tanks at the head of a line, showed a velocity of leaa thaa,
in. per second, care should be taken to flush the sewers either by a h*
or some equivalent. In the ca.se of combined sewers he endeavored
to secure a nominal niinirnum velocity of 2-1/2 ft. per second. In p
tically every case where he ha^ had occasion to study in detail the coi
t ion of intercepting lines, a heavy grit has been found deposited in tin
If these deposits were not removed, they apparently decomposed
became more or less cemented by ferrous sulphide. The result was that
scouring velocity applicable to ordinary street wash would not longer
suffice. This be found quite marked in Elizabeth, N. J., although
the data are too meager to find place in a record of accurate information*
C. E, Grunsky statetl that the minimum grades in Califomian cities,
reported to him by the engineers of the places named, were given
Table 27. The city engineer of Stockton said that the grades in

i

I

anT

Table 27. — Minimum Guades in Caliporxia Cities

m

^i%Q> Stockton,
inchea per cent.

Frt»aot
I>er ccjjt.

Modcjto, Viaalift,
ppr cvtxt. per cent.

prf rwnt.

a

8
10
13

15

in

0.2
0,143
0.130
0.1

0.15
0,1
0.1
0.1

0.10
0.10
0.2

0.152 !
0.09 !

0,3
0 24
0,143

o.ua

0 '^5
0 2

o.ia

0.1

::''*'*:i

city have given no trouble during the 25 years they have been in servi^
these sewers carry only sewage, rain water being ejccludefl. Once iti
great while they have had Bome trouble from deposits at Fresno^
to sluggish flow, according to the city engineer. The city englneerj
Visaha stated that he had made float measurements of the sewere
found that the actual minimum velocity when they were miming
third to one*haJf full, was 1.1 ft. per second in 10-in. sewers, and a velfl
ity of 1.75 ft. per second was ob8er\xd in an 18-in. sewer half full.
light grades caused no trouble in that city. The city engineer]
Sacramento stated that the depth of flow in the sewers of his city
not average one-fourth of their diameters; in no case had there
any oflfensive deposits,

T. Chatkley Hatton in experiments with two 24-in. sewers dischu
ing creek water carr>^ing considerable clay, the grade being 0,077
cent., found no appreciable sediment with the following deptlis
inches and velocities in feet per second :

Depth 5 12 12

Velocity 1.21 2.U I 70

A lejander Potter stated that his general practice was to lay all sewc
4 grade giving a velocity^ when flowing half full, of at leaat 2 (U

VELOCITIES AND GRADES

121

>

id and preferably 2-1/2 ft. With gi'ades giving velocities much less
2 ft. 5K;r secontl when flowing half-full, flushing and frequent clean-
tog urc necessary. In order to avoid pumping or castly construction^
however, Mr. Potter has used very flat gradeis at times. At Hafrifion,
X. Y., ahout 5000 ft. of 20-in. sewer was laid with a fall of only LI ft.
pfif thoiuiiLod. As the average flow will never more than quarter fill
the pipe, arrangement ha§ been made to flush it automatically once a
cUy. At Kingsville, Tex., in order to avoid pumping, sewers flushed
aulotniitically once a day have been laid on grades as low as O.i per cent
for l8-in, and 15-in.; 0.15 per cent, for 12-in., 0.2 per cent, for 10-in.,
ifld 0.33 per cent, for 8-in. Id the southern part of Texiis where the land
b very flat many 8-in, sewers have been laid with a fall of only 2 ft. per
tboUMAtid. In Corpus Cbristi, Tex., Mr. Potter found that practically
«n K-m, laterals had been laid with a minimum grade of 0.2 per cent.,
lod were kept clean by frequent flushing.

»

EIAMmATION OF SEWER DESIGN WITH REFERENCE TO
MINIMUM FLOW CONDITIONS

I.<^nn,)DHc considerations generally require the construction of main
oriiitirif [ittng sowers to meet future rather than present needs, Tlie
length of the period to be cared for will be determined by the attendant
cimiriistAnreH^ but in general these sewers are designed to meet the
W«d« of a period of from thirty to fifty years. As a result of this, the
flow in the «ewer for a long period of time will be much below the normal
OQodillons for which it is designed.

It k necessary, therefore, after designing a sewer for a given service
h tiie future, to consider the actual cotiditions of operation likely to
wisf under dry weather or minimum flow during the first few years
i^<»f ^ruction, in order to make certain that the velocities will

not for significant periods of time, as to cause serious deposits

in the sewer, the removal of which w^ould involve unwarranted cost.
Tbo construction of a sewer to serve for the long periods assumed above
would be unwarranted if the cost thus resulting should exceed the cost
o' * Hrr sewer in the first instance, to serv^e for a shorter

F^i i until the anticipated growth had developed in some

^^V^f tttid of then building a second sewer to take care of the additional
•^tfcfc flow rc**ulting from the added growth* Wliile the latter plan
wwuM itivf»lv*» greutrr fimt cost of construction » enougfi might be saved
tt> ^ ^^ and in the cost of operation^ in the early years of the

\im: . . ALT, to more than cover this increased coat.

An ttxampli! of such a computation is shown in Table 28. It will be

r ' 14 that the estimated velocities under full flow* thirty

Justruction of the sewer, range from 2.4 to 3,1 ft, per

122

AMERICAN SEWERAGE PRACTICE

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hercas the velocities for the anticipated dry weather flow at the
; of the period range, in general, from 1.7 ft, to 2,1 ft, per see-
though at the head of the sewer, velocities as low as M ft, per
and were anticipated.
It k desirable that the sewer sections and slopes should be so de-
8%iied that the velocity of flow will increase progressively^ or at least
maintained, in passing from the inlets to the outlet of the sewer,
tliat solids washed into the sewer and picked up and transported by
Uie n ream may be carried through and out of the aewer, and

M f d at some point owing to a decrease in velocity.

It id obvious that the velocity of flow is but one of many factors in-
lived which must be given consideration in such an economic study;
[ nevenheloBB, it is one which should be carefully weighed and not lost
lighl <vf.
Velocity in Submerged Sewers.^ — Computations relative to the dry
her and minimum flows in submerged sewers, particularly such as
r outfalls, must also be made, for here the conditions tending toward
[ ^logging of the sewer are particularly aggravated. Unloas grit chambers
J devices for removing the heavy mineral matter are provided,
' of clogging maj' be serious. This danger arises from the fact
; where the pipe is submerged, flow takes place in the entire cross*
[ tection and with a given rate of flow the velocity may thus be reduced to
I nc^tHling!y small limits.

Fortunately, however, the matter in suspension, if of orgar ic character
konly, tends to remain in a scmi-fiocculent condition, buoyed up in part
mitalow specifie gravity and in part by the rising bubbles of gas formed
jBy itfl putrrfactinn, so that if the sewer does discharge under substantial
veirK-ity from tirno to time during the day, or even at longer inter\^als,
[till flow may maintain the sewer reasonably free from clogging deposit.
If <iuch outfalls are into salt water, the effect of the difference in spe-
[^dfe gravity uf the two liquids is to be borne in mind as well as the fact
[.Ihe salt water tends to precipitate the suspended organic matter
I quickly than does fresh water,
nmli Tanks for Dead Ends. — The difficulty of obtaining adequate
f^ities of flow ill the extremities of the sewer pipe system, where the
[f^ie3< aro, of nreessity, very flat, is met by the use of flush tanks or by
Dg t s periodically in other w^ays. Such devices though

nrj^ rtiun cimditions are, at best, a source of annoyance and

[^lecMo on account of the difficulty of making them operate regularly
mlly and of the expense of furnishing water for the purpose of
Moreover, the action profluccd in the sewer by the discharge
lu»h lank is a purely local one as the influence of the flood wave
but a short time nnd in n comparatively short distance, ti&
hipUined in Chapter XV.

124 AMERICAN SEWERAGE PRACTICE

HYDRAULIC ELEMENTS OF SOME STANDARD SEWER
SECTIONS

In Figs. 38 to 41, inclusive, are given the hydraulic elements of
certain standard sewer sections, which have been figured by the applica-
tion of the principles outlined in this chapter. The computation of the
elements of sewer sections other than the circular is a rather long process
and can be considerably lightened by using a planimeter where extreme
accuracy is not desired. The hydraulic elements of other sections
are given in Chapter XI on the design of masonry sewers.

VELOCITIES AND GRADES

125

r

o

I"
%

CM

o
00

OjO af 0.1 0.3 0.4 O.S 0.6 0.7 0,1 03 f.O M 11
totio of HydrauUt EJenien1> of PtHed Segmtnt tothoM of Entire Section ,

^0. 38,— llydmiilic dem<jnta of circuljir section by Kuttcr's formulri.
••^.OlB; • - 0.0003; £) - 7| ft. Arcii * 0.785D<; Wcited Pcrimolor - U.HLOf;

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^' C » 50 4i8 50 SO 70 ^ 30 IDO 110 120 130 140 ISO Diachory {c« 1>, per s«t>
-HjftfSQlie dismeota of Bomi-eUiptio sc^ctian by Kutier'n formula.
« • 0,013; « « 0.0003.

AMERICAN SBWERAGE PRACTICE

0 "0 20 30 40 SO Areo(ftq.1r.)

SJ^!^ 0^ Q-* ' Q UL 1.4 r.fe l» 10 MydraulicRodiua (fK>

...,.: ^ Velocity (fr.p«rs«.)

0 to 20 50 40 50 60 70 SO 90 too 110 l?0 tiO m 150 Oiu>>ar^eCcu>.peri

I-'to. 40 — Hvdrauli*) elements nf horseshoe section, Wftchusett tyjM

K II Iter's formula,
n ^ U 013; a - 0 0003.

0 1^ LO 3J9 4jO SiO Areo (&q,fr.)

go 02 ft* at OS I J 12 i4 i.e j^ Z-^. I^X^'^"^!'- Ff*^'"*/^^!

0 10 a» 30 40 50 ^0 70 tO 90 100 HO 120 130 MO ISO OtKhar^ctcbL^, ptrMt

no. 4L — tlvdmuUc dements of

* N<*iiiHeUiptioal woiloa by Kut

CHAPTER IV
MEASUREMENT OF FLOWING WATER

Tho (fij?charge from sewers or drains may bo measured by the following
iiiffpreiit methrxLi, the choice depending upon the conditions found:

1, By weighing the discharge for a given period of time in tanks or
other receptacles.

1 By measuring ilie discharge for a given period of time in tanks or
(rtijiT receptacles, the contents of which can be accurately gaged.
3. By standard orifices.

^. By itandard weirs of the rectangular, triangular or trapezoidal
lorrn,
y By Venturi meter.
<1. By current meter.
7. By float measiurements*

S, By ohticn^ing the depth of flow at two adjacent points, when ft fair
ooodition of hydraulic equilif>rium has been reached, and figuring the
falutfge under the given hydraulic elements, depth, slope and area of
Ot»H»ction, by suitable formulas.

%9 ude of the Pitot tube, which has proved so useful in clear water

'"'*'" ** "^ r- .-:..-, IS impracticable in sewer gagings, on account of the

coiitaijied in the sewage. Nozzles are also of little

tt of luck of pressure.

: ijwing paragraphs ivill be found a brief discussion, with

*rc«jinpanyiiig funnulas, tables and curves for convenience in eomputa-

' ' ' ^ ircment by orifice, weir, Venturi meter, float, or

ipplifatiun of the formulas already discussed to

I of the quantity of sewage flowing in any sower

..,. ,^ ..iiiation, the method being at best an approximation

it upon the steadiness of the flow at the time of observation

»■ * with which the coefficient of rouglmess is estimated

"*'' >ndili<>Ti8. Nevertheless, the last method is the one

ity used in ordinary sewerage work and is sufficient for the

-Ht,Mrint*!udeut of sewers in his everyday practice. For

ions, one of the other methods suggested must be used.

d upon the facilities at hand, the degree

ronditions under wliich the sewer was

I is opcTu

' -^her Ui 1 u-'i,FU ii|»on the measurement of flow in sewers,
be had to Chapters VI and IX.
127

-^ -"-•

•^"-^^'^

128

AMERICAN SEWERAGE PRACTICE

Discharge through Orifices. — In accordance with TorricGlli's theorem,
that the velocity of flow through the orifice is equal to the veiocity
acquired by a freely fallinp; body in a space corresponding to the head
over the orifice, the discharge through an orifice is as follows:

Q=cav^m V2p/i, in which
0= quantity, in cubic foot per seco&d
c = coefli€ient of discharge
a — net area of orifice, in square feet
tf~ velocity, in feet per second

A = head, in feet, from center of orifice to surface ol watar
f^- acceleration of gravity =32.16

The coefficient c is required by reason of the fact that the cross-^^^^!'^'^
of tlie jet, at a point a short distance outside the orifice, has gen^
somewhat smaller area than that of the orifice itself, the rcdm i
area depeniling upon the character of the orifice* Wlien the •
the orifice is sharp so that tlie water does not adhere to the orific^^ ilie
coefficient is at a minimum or the reduction in area is at a maxinuim.
When, on the other hand, the orifice is shaped to a bell-moutlj, the
coefficient is at a maximum and the cross-section of the jet may bo newiy
equal to that of the orifice itself.

The section at which this reduction in area is at a maxiinuni is kncjro
as the ^'contracted vein" and experiment indicates that the \'elc- '*' '
the water follows Torricelli^s law literally in this section. The
of the contracted vein generally lies at a distance from the oti&co U
five-tenths to eight-tenths of it« least diameter.

Table 29, from Hughes & Baflford's "Hydraulics/' ahowa tlie a|>pnncS>
mate variation in coefficients of orifices for a circular orifice of dtaincilcf
0.033 ft. and for heads of from 1 to 10 ft.

!i

i'lliiiii
mm

i!lt il!

II

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iMniiiit

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^

r

A. B. C, 0. E.

Taulk 29. — AppKoxiMAiE Variation in Co£FnctENTS

1 A 1 B 1 C 1 D

C

180» 167r 1 135- im*
0.511 0 MO 1 0 577 0 6O0

o7r iS'' 2?r iir «r

O.Oftt f> 75:1 0 tW2 i) W2i 0 *€» A^j

The sittndard orifice, as generally defined, is one in which the edged!
the tfrifiro whirh flotermines the jet is sui^h that the jet upon les^iuf ^

MSASVREMEiVT OF FLOWING WATER

129

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130

AMERICAN SEWERAGE PRACTICE

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I

MEASUREMENT OF FLOWfNG WATER

131

I

doci not afcain touch the waU of the orifice. Prftcticftlly, this result i«

' l<y having the outside of the orifice bevelled and its throat
1 in shape with a cylinder length of between tV and } in.,de»
pending upon the thickness of the plate.

Merrinmn defines it as ^signifying that; '^The opening is m arranpod that

the Winter in flowing from it (the orifice) touches only a tino a^ Wiiuld bc' Iho

ktMQ Iq & plate of no thickness. To sc^cure this renutt, iHc inncT mlgc of the

Lftpctiing ha« a square corner which alone is touched by tho water. ♦ * ♦ • •

|Th« orifice in a (hin plate is often uaed to express the condition that the water

loiUy loudi the edges of the opening along the line. Thii* arrai*«timnnt

fhe regarded as a kind of standar*! apparatus for tho ni oa^urtinivivt of

Hughes and Safford, '* Hydraulics/' p. 130, have, however, defined the
; iUndjkrd orifice as follows:

'if wi oHBce in a thin wall is »ct far enough from the side of tho ves^ol or
f thannel to iiecure full contraction of the jet, ia round or wquare, anci har* no
dmm&0nB greater than one foot (for which shapefl and dimensions reliable
^oefioiiillB are available), it is called a standard orifice/'

W«iiB» — One of the most accurate methods of measuring water is by
fcemnj of wein, pro\ided the conditions under which the coefiicienta of
of p" "i of weirs were determbed are approximately

Til niuion typeia of weirs are the rectangular, the V-shaped and

wcin
n ig data have been abstracted from Hughes and Ba^urd'i

''Hyttra.uljce," 191 1 , to which the reader is referred for a fuller dincuwion,

r'r,..,f i-e iff ^ Folhwtd in Weir MeasurffucnU. — (I) Con«trurt.ing tmd
thfi wfur and the gage for measuring the head; reproducing, it
"i-xTur 111© oxportmeotal conditions of the formula to be u«ed.
(Zl MoMoing the length of the crest ami determining it« irreguUritiiM

II) Tiking a pra6le of the crest if nc»t sharp-edged.
(Q DiHcnBtoisig by actual measurements the croes •ectional srea of the
ltd apprc^rh.

I by lereling the relative elevations of the crent of the weir^
'•< Uiegite.
? desired ragtilaitoa of flow is established, determtnang the
lirj z^M»4^ ^M^ or oilier obeerratioiis at Intervals m frequent as the oondi-

aetinl velocsly in the channel of approAth by a
or ««iie otlier direct nMibod^aad
Ibe daerbefige by tbe formttla selecied.
opcrmtacMis ret n>m *iiig<iiil eomideralioii, wh^ fOMtnae*
tke faaeMrameot of the heed, aad the selertina td the

132

AMERICAN SEWERAGE PRACTICE

Connlrudipn ami Setling of Weirs, — (1) A sharp-crested weir with ca
plete QTGst contraction ahoultl be userl,

(2) The nrest should be level, and it^ enda vertical

(3) The end contractions should be completej or, if suppressed^ entirely
suppressed.

(4) The upstream face should be vertical; the downstream so desig
that the nappe has free overfalL

(5) Free access for air under the nappe should be made certain,

(6) The weir should be set at right angles to the direction of flow,

(7) The channel of approach should be straight for at least 25 U. Above
the weu-, of practically uniforna cross-section, and of alight slope (preferably
none)*

(8) Screens of coarse wire or baffles of wood shoultJ be set in the channel,
if necessary, to equalize the velocities in different parts of the channelj
not nearer the crest than 25 ft.

(9 J The channel of approach should have a large crosa-scctionalj
order to keep the velocity of approach low.

itirely

I

Above
irably

channel,

'4

Measurement of Head^—l^he head above the crest of the weir should-,
be measured, preferably, by a hook gage with vernier scale upc
reading to thousandths of a foot.

For approximate results, the gagings may be made from a peg drS^
into the bed of the stream at a distance of several feet above and to i
side of the weir. But for careful or precise measurements tlie gagij
must be oiade in a still box, the loeatioD of which should meet the follow- '
itig essential conditions:

mig|j

fiush i

-|

»et^

(1) The cross-sectional area of the communicating opomng or pipe
be sufficient to allow free communication with the channel even when th
tied.

(2) The channel end of this opening must be set into and exactly fiush^^
with the flat walls of the channel, or into a flat surface laid parallel to |
direction of flow, and the pipe itself must be normal to the direction of 1

(3) The channel end of this opening must be located far enough upatre
to avoid the slope of the surface curve, and not far enough to increase 1
observed head by the natural slope of the stream.

The area of increased pressure, which forms above tJie bottom, beginc
at the upstream face of the wen* and extending upstream, perhajis ah
to the beginning of the surface curve/ once thought to be a location at wU
the observed head would include the velocity head, hajs been proved to 1
poor location for the opening.

Avoid perforatetl pipes, no matter where the holos are bored, laid i
versely or longitudinally in the stream at different depths: avoid i
piezomtjters of any form which project in any du-ection into the st
After the Lowell hydraulic experimentt? were made, Francis sc»metimC8 1
pipes with hole?; bore<l in n vortical plane m order to secure an average j
sttra across the stream, in rocognition of the fact that the surface la |

1 S«« VUiii^r ftod ^loftnuu Trant. Aw. Sao. C E., Vol 13* p. 42, PUte I V.

MEASUREMENT OF FLOWING WATER 133

tnuunr«r«elx level. Since hia time, this has been shown to be a vicious
yimrticc, which may introtluee more errors than it ww* designeti to obviatis.
Tbe (tmmtial conditions of looation of a Ktill box will in general be met if
il^upeainfT ls »et well Uf>stream from the beginning of the surface curve, and
it nr a few inches below the crest level.

If Francw >j» Fteley an<l 8tearns\ Bazin^s, or any particular experimenter's
^(ijrmulJi IS to be used, his location should be duplicated (p, 200, Hughe^s and
Sifffif^J'i Flydraidir^),

Mttuturt^nuntn of Head in franri^'s Eiperiimnt*. — The head was observed
[^l*y t»o hook gages, one on each side of the channel, aet in still boxes which
1 18 in. long by 1 1 in. wide. Communication with the channel was made
> oontractod weir meiLSurements by a l-in. diameter hole in tlie bottom
FiMih box» located T) ft. uf»stream from the weir and 4 in. lower than the
g^ bf <1 of Uie crest. For the suppressed weir, comifjimication was established
I^^^Hpes B, opening into the sides of the channel 1 ft. lower than the level
^^^Hl f^est, or by the single opening for the pipes 4 and 5 which were set
^Bb fita boanl C • • • * * All tliree openings use<l were therefore 6 ft.
I^B upf treiim from the w*eir. To prevent rapid oscillations, the openings were
tiffotded by a perforated plug set on the inside of the still boxes (p. 204,
cit.).
MuiMuttmtnU of Head in FUley ami Stearm* Experiments, — ^* * * ♦ * ^jj^
L by hook gages set in still boxes which wore connected with
pipes. Although the actual form of piezometer openings
^ tbe essential condition that the opening be at or below the crest in
nal to a flat surface parallel to the direction of Sow, was in all cases
killed* The location of each opening is stated in the table '^ (p. 208,

J
a/ Weir Formula may be expressc^d b}^ the e^iualion Q == CLll ,

To Ihii form all the t^quations in use may be reduced, but it is better

in virw of the several methods of correcting for the velocity of

followed by the various experimeuters, to use their form of

uitioft.

TheFmncU Weirfarmida,

Lrt Q> discharge in cubic feet per secoml,
£ = length of crest of weir in feet,
A* = number of end contractions,

ff-lbe observed head corrected to judutlo the effect of the veloc-
ity (if approach I

rved head upon tbe crest of weir, being the difference
t ion in feet between the top of the crest and the sur-
face of the water in the channel, at a point upstream^ which
^uulii, if fM>ssible, be taken just beyond the beginning of tbe
Mirface curve,

I duo to the mean velocity of approach
lu feet per second*

^^^^ 134 AMBHiCAN SEWERAGE PRACTICE ^^H

^^^^^H TABJ.E 32,— Weir Dischahgeb and Velocitibs i>t'f Tfi Headj^ proi^H

^^^^B 0.00 TO 2.99 FT. ^M

^^^^^H ^H

^^^^^^^ 9^antity of water in cubic feol p*»r d^'conrl, dinrhnrK* «i h i^^^^I^H

^^^^^F wrtr to have complete coiitractton oo its crest, and to have w "^^^^^^H

^^^H Q-3.31 L //K+ 0.007 L for dc-pths up to 0,5' iirid Q - 3.:i3 L //' for o >y^^^B

Vd. due to hesd eomputad by formuln Vtl, - v 2 qH ^

,-

J

■

^

. * ^ • .1

H So.

■§1

H

u

^i

i H

C7-

6*

H

3=^ ^a

H

S=^ 4J

feet 3 ?

foot

<H

>^ 1

1

feet

3 - « ^

f^t

<H ^1

1 «

^ \ ]

1

6

C

^ "*1

o.ool., A.^Jlo.w

i.asU 21'

1. 10*4, 38

8 79

i.lO

8 0410 ?n'' 1 4o|i^ .islia li

.01

0,010.80

.61

.59G 20

.11 43

8.82

.81

1- ■■ ' -■' .41

.46 12 1

.0«

.02 1,131

SS

.tUti 32

IS .49

8 8ti

.83

41

.51 12 4

.OS

.02 1,39,

SS

.OGti 37

.IS .54

S.S9

.83

.48

-ttl 12 4

.04

.03 l.WJi

.94

.70 6.42,

.141 .60

8 93

.84

44

m\ 12 5

.OS

.04 1 79

IS

,74 i> 47;

,11* ,65

8 97

.88

46

77 12 ISi

.0«

.0*V1 ftol

.SS

.79 6 52

IS' .71

9 <X)

.86

48

-85 12. Si

.07

.07,2 12

.47

,83 6.55,

,17

.77

9 tM

.87

47

-93 12 «

Oi

.082.27

.SI

.87 6.«i;

.SI

.82

9 07

.88

48

13 (10 12. «

Of

.103.41

.SS

*91 6.06

.ts

.88

9.U

.69

.49

.08 12.«

0.10

O.U|2.54

0.70

i.g5'e.7i

t.to

4.04

0.14

1.90

6.72111.051: 1.80

13.l6'l5.4

.11

.132.05

.71

.99 6,76

.11

.09

9 18

.91

.7911 08. 1 .81

.24 12 7

.11

.14:2.78

.71

2.03 6 81

.19 5 05

9.21

.91

.86 11 11 .61

.32112.1

.It

.1612.89'

.71

,0*0.85

ISi .U

0 26

.93

.03 11 14 .88

.40 12 7

.14

.1813. 00;

.74

.12 6.90

.S4 .16

9 28'

.94

0 00 11 17! .84

.48 12 I

.l»

.203.1]

.71

.16 6 95

.IS .22

9 :i2

.96 .07 n 201 ,88

.56 12 §

le

.223 21

.71

.21 ^m

.is' ,28

9 3r.

.961 14 112:1 81

,6t 12 S

-17

.243 31

.77

. 25 7 04

.17 .34

9 30

.97

.21 11 26, .87

.72 12 1

.IS

.26 3.40

.71

,29 7.08

.Hi .40

Q 42)

.98

.2811 29 .81

.80 %2 %

.11

.283.60

.79

.34^7.13

.19 .46

0.46

.99

.SSjH.aii ,81

.tei».«

0.10

(},30'3.50

0 BO

2,3s'7,17

1 405,52

0 49'

S 00

9 :■•'- ^. -rn-^.a'iia

.11

.33 3 68

.SI

.43 7.22:

,41: .57

0 52 01

ss

.35 3.70

.SI

.47 7.2t"»

.41

.63

9 ^i\ 1 .01

.IS

,37 3.85

.SS

.62 7 31

48

.09

9 59 .OS

63

-.'<> nrlH

.14

.403.03

.14

.5417.35'

.44

.75

9 62, .04

84

.2s 13 m

.11

.42 1.01

.19

.61 7,39

.46

.81

9 66

.08

68

.36 t:t (il

.IS

.45 4.09

.11

.66 7.44

.48

.87

9 09

.06

6«

45 rt ol

,17

.47 4 17

.17

.70 7 48

.47

,93

9 72

.07 67

.5,^1.1 jl

.IS

,50 4.24!

.81

.75 7 62

.486. Of)

9 76

.08 88

.(U 13 ll

.19

.52,4.32i

.11

.80,7.57

.49. ,06

9,79

. .09 iO.iM^ i[..y.i .69

1 1 1 ^1
1,10 10. 13' n 62;' 1,70

.69 I't.lfl

0 so

0 SS'l-SD

0.90

2.84T 61 'l.io'6-12' 9.82'

14 77 U.ll

SI

.58 4 47

.91

.89 7.65;

.81

.18 9 86

,11

.21 n 65 .71

.80iijfl

SI

.61 4 ,^4

,91

.94 7.69

.U

,24> 0.8H

.11

,28 11.6^ ,71

>^I^H

ss

«3 1 tVl

.9S

.99 7 731

.88

.30 9 92

.18

,3,5 n 70 71

15.0lf^H

S4

-04J4 08

.94 3.037-78;

.84

,36 9 95

.14

42ll.7:t ,74

.loTini

ss

Gy 4 71

,9B .OH 7.82;

.88

.43' 9 9JS

.18

50 1176 78

.I9{I39

s«

-72 4 ^1

.91 .13 7.86

,86

.49 10 U2

IS

.57 n 70 .76

27 u a

S7

.7:1 4 *iS

.97 ,187901

.87

.56 10,05

.17

77

.a5 IH.tt

SS

,7.H4 t>i

.9S .23 7 94

,88

.61 10,08

! .18

78

ij'ut a

39

,815.01 ; .99| ,287,98^

89

.6810.11

1 ■"

79

.52 U.l^g

0 40

0,^15.07

1.00l3,33 8 02 1 SO

rt.74'lO.!4

1,10 10,87 a fH) 9 10

15.6ri'n 1I

41

88 5 H

.01

.38S tXj ,Sl

.80 10.18

.111 flu 11 "J SI

09 1:; m

41

.91 5 2U

,01

.43|h 10 .91

.87 10 21

,11 n ■- SS

.77 u a

41

.t>4 > 26

.08

.4S|8.U| .11

.93 10.24

SSI S3

85 13. 4i

,44

•t: ,*T \:

04

.v?^ m" .14

90 10 27

14 84

ui i:t^

.441 ■■ ' ns' ?5'' ■ ■" :;- ss m.n2 i.^ n

.49 S4 H U ■

,47; -S7, .tv .U.a

,41 ,11 0 .Ui .08^ 71 s ,M ,&8 .-:.* in 4*) a» n. 1- n .11

..'7{t.TM

.41 ,14i5,6Ilj .19 .79,8. »7I .«•! .3;f|lU.43| ^M^^ .54(12.14 1 *§•

.^isj

- mU|

41

^^1

j'^H

.93, « .:o'!^i

,S4l 94

,79 13 11

SS 95

.^7|U a

.14 --

.17

' i^^^^^^i

.11, . :.

[ f^^^^^^i

.SSi ..^1 ■ Hi 1% .i*' -* :.^ .t» It? Ul 7,i s* ,ui \: n> ; 99 ^.*,T1«^^H

1 1 ! 1 1 i| 1 1 1 J 1) ' 1 ^H

MEASUREMENT OF FLOWING WATER

135

^^^^ 134 AMERICAN SEWERAGE PRACTICE

■

^^^^^1 Tablb 32.— Weir Discharges akd Yelocittes dff

Tr> Hl*AT>fl rROll J

^^^^^1 0.00 TO 2,09 FT,

M

^^^^^^P

fl

^^^^^^^" Quniitity of watrr in cubic feet pt-r mn'oad, dijwhiirittMl «>>- f

,

;;^^l

^^^^^F Wf'tr to hnx'c complete coatraction on its cre-st, iind to have u-

^^^B g-3.31 L //f+0.(K>7 L for dcpthis up to 0,5' «»nd Q -3.33 L //? fo

f

:^|^1

IV. due to h(>ad computed by formulsi VrL^\'2 (fh

]

■

m

•

■

.

m

■

H Si

i-

H
fwt

1 H
'feet

6*

H

feet

it

> **

u
f«pl

0^

y

^

1

©"

^ 1

V*

<>

t}

*

]

o.o«L,..L...I

o.ioli.s^U 21I

1.10*4.38

8.70

1.80

8.04'l0.76

1 40

l2.?tsS2 43|

.OIO.OIO.SO

.41

.59 6.26

ll; .43

8 S2|

.41

.11 10 to'

.41

.46 ia,«

.(M

.021 1.13

.41

,63 6 32,

.111 .40

8 86

.48

.18 10 82

.41

54,12,^

.0«

.a2|l 30,

.48

.66 6.37

,18 ..54

8 89

.83

.24 10 85

.48

.61 12. (

.04

.03|lJVf>l

.44

.70 6.42

.14 .tU»

8 93

.84

.31 10.88

.44

.69112. i

.OB

.041. 79

.44

.7416.47

.14 .65

8 97i

.88

.38 10 91,

.44

.77 12;

.0*

.Oftil 9(ii

,44

.79:6.62

.14 .71

9.m

.84

.45 10.94,

.44

,85ll2.^

.or

.07

2.12

.47

,83 6,56

.17 .77

0 04

.47

.51,10 07i

,47

.03 12 1

oi

.08

2.27

.48

.876.611

.14

-82

9 07

.48

.58

11 00)

.48

13.00 12 <

,o» at;

2.41

.41

.01,6.66,

.19

.88

o.n

.41

^'"^

n,03j

.41

.li8 12 (
1

0. 10 0.11

2 M

0.70

l.06 6.7l''l.W4,94

0 14

1.90

8.72

11,05'

1 40

I3.16'l2.4

,11

.13

2.66

,71

.0M6 76

.11 m

9 18

.91

.70 11 08

41

,24 12 f

.11

.14

2.7S

,71

2.03 6.81

,18,5.05

9.21

.91

. 86 n , 11

,61

.32,12 7

.11

An

2.80

.71

.08 6 85

.131 .11

9 25

.93

.93 11 14

.81

,40 12 t

.14

.1813,00

.74

.12 6 00

.14* .16

0 28

.94

9 on 11 17

,64

.48 VIA

.14

.20,3.11

.74

.16 6 95

.14; .23

9 .321

.94

.07,11 20!

.44

.56 12 S

.14

.223. 21

.74

.21 6.90

.14 .28

0 351

.94

.14 11 23

.44

AW Vi\

.17 .2413 31

.77

.25 7 04

.17 .34

9 :V9'

.97

.21 1 1 20

,47

.72 12 i

.18;! .2G:i.40

.74

.297.08

.14 -40

0 42!

.94

.28 11.20

44

80 12 1

.11* .2sa.5g

.79

.34 7.13

.t9j .46

9.46

.99

.35,11.31

.49

.&8|U.g

0-10 0.30 :i.5»

0.40 2.38'7.17l

1.405.52

0 40

8 00

9.42'u.34

1 40

fr. ^J... ^

.SI; .333 c\8

.41

.43:7.22

.41

.57

9 521

.01

.49 11 37|

41

' 'll]

.42, ..'if,, 3. 70

.81

.47 7,20

.41

.63

0 56

.01

.56 11-40

.41

'ij

.14 .37 3.K5

.48

.62 7.31

.48

.60

0 59

.03

.63 11.43

.44

. .'II I J U|J

.14 .40l3.fl3

.44

,.56; 7. 36

.44

,75

0.62

.04

.7011 46

.44

>28|i?i ql

.14 .42^.01

.48

.01 7.39

.44

.81

0,66

.04

,77 11 4h'

.44

.36|U H

.14 .4«4 00

.84

.667 44

.44

.87

0,69

.04

.44

.4.5 IS.Qfl

.17 .47 4 17

.47

.70 7 48

.47

.03

9.72

.07

47

. 5vl 1 3 . tl

.14 .50!4.24

.44

.75 7.52

.486. 00: 9 761

.08

44

,61 13 Xm

.19; .52
1

4.32

.19

.80,7.67

.49

.00 0.79

.09 10. nil 1 J, ..v'f
l.lo'lO. 13111. 02

49

.60 13. ll

0K»0.55

i,30

0.90 2.84^.6]!

1.40

6.12 0.82

llTO

14 77 UjI

.11

.hs

4.47

,91

.897.65

.41

.18 0.86

.11

.21 11 65

71

.11

.01

4 a*

.91

.94|7 69

.41

.24 O.SOl

.11

.2N 11 i\S

71

• 044^^^|

.84

63

4 61

.98

.09i7,73

.48

.30

0.02

.13

.35 11 70

.78

15.091^^^1

14

.66

4.68

.94

3.037,78

.44

.36

0 05

.14

.42 11.73]

,74

. 10]^^

.84

.«\>

4 74

.94

,0817.82

,44

.43

9 08

.14

.50 11.761

,74

. lol 13

84

.72|4 81

.94

.13

7.86

.44

.40 10.02

.14

.57 11.79

74

-27i»3

87

.7G|4 881

,97

.18

7.00

.47

.6fi| 10.05

,17

,64|11.81

77

.as'is

,84

.78 4.94!

.94

.23

7 94

.84

.61 10.08

.14

.7211.84

78

43 u

.89

.815.01.

.91

.28

7.08

.41

.68.10.11

.19

.79|11.87

.79

-&2ji:i

0.40

0.S4 5 07

1 00

3.33

8.02

1.60

6.74 10.14

1.10

10.87 11,00

1 40

15-60 '11

,41

m^Ai

,01

.38

8 <I6

.41

.8010, 18

.11

,0411. 92

,41

.60 13

.41

.91 5 2U

,(»

.a:\

s 10

41

.87 10 21

.19

11, 01 n 05

49

77 n

At

.045 2n

.03

.4^|^.14

.63

.0.1 10 24

,13

.O'JjH.'J.S,

48

i*5 13

.44

.97 5 32,

04

.5:its. IH|

.44

.99 10 27

.14

\iA'2 o*y

44

04 13, i

.44 1.01 5 38,

.04

.5HH.'J2

,44 7.001 10.301

.li

44

16 OJi W

.44 .OlTi 44

.04

.63 8 26

.44 .12:10 .^31

.14

44

n 13 4

.471 .07 5 50

.07

.69 8 3(1

.47

.19 10 36

.17

47

10 \%

.411 .lll5 56

.04

,74 8.33

.44

.25 10.40

.14 .I'M- 11

.44

.27 la.

.48| .U|5.dl

.09

.70 8,37

.49

.32 10.43

.191 .54112,14

••

.3e izj

0 4Ol,lft'.V07

1 10

3, 848-41

l.TO

7.38 10 46

1.80 11 (W 12 16

1.90

T r '^ B

.41 .21 5 731

.11

.89 8.45

71

.45,10 4lt

81; .611112 10

91

-,

41

.2.5 5 78

.11

.0.V8.40

.71

,51 10,52|

.81 .77 1LV22

.91

""

.43

,2Hri S4

.11:4 (KJ8.53:

,73

..'i.SjlO 55I

.83 r- ■'

.98

/" ! ' . ;.;

.44

:i2 5 m

.14

,058 5i;

,74

JH 10 58!

,84'

94

71+ 1..

.44

..3n.:. 'jr,

.14

.11 8 l«3

,74

.71 10 61

.84 12

94

.H7 i...;^i

.44

,3U ti 01),

.14

,1« 8 04

,74

,77 10 ti4

.84

n-

^^^^tm

.47

.4.1ft.0G

,17

.21 8 <;h

,77

.84 10 n7i

.87

I

^^^^^^H

.44

.471; 111

14

,27 S 71

78

,01! 10 70

811

■ I

^^^^^^1

49

.51 itUj

19

.,^2 8 75

.79

. 07110. 73|

.89| .........

i "

^i

OTP

n

1

MBASVREMENT OF FLOWING WATER

135

J

I -8

Iff'

•^^

^^H 134 AMEBWAN SEWERAGE PRACTICE ^H

^^^^1 Table 32.— Wei h Di»CRAnoEs and VsLoctTiEs due to HEAoi^

^^^H 0.00 TO 2.99 FT. 1

^^^^H 1

^^^^^^^B Quiinlity of water in cubic fi?et pc-r mt^cnnd, disvhiirKcd ovor n wcir 1 ft. loM

^^^^^^H wi'tr to hav« complete cuuirucLion on ita orent, nntl to liJive ao'eiid contr^

^^^^1 Q*3.3l L //i^-OOO? L for depthn up io 0.5' nnd Q » 3.33 /.//! fnr dopMiH (vbov^

^^^^^H

Vtt. diw* lo head eomputeil by formulft Fc/. -V2 tfA J

H id

-si

H

IB

c^

H

•

if

ll:

H

m

i 1 1 H

'«t U.'

>"

feet

3 :

a-

5. a

1 tcei

>^

feet

a -

> ^ [ f*''^'-

<^:

1 &

*" 1

c

1

V

^ \

V

*" I

<>

o.oot '...J

0.00 1.55

0 2l'

1. 10^.38

8.79'

1.80

8.(m'i0.7G 8 40

12,38 ;

.010.010.80

.01

.50

fl 20

.11 .43

8 82

.81

.11 to. 79! 41

,40

J)t

.02 1 13

.01

.03

0 32

.11 .49

8 80

.81

.18 10 821 .41

.54!:

.01

.02 1.311

.03

.OOlO 37

.13 .54

8.89

.83

.24 10.85 .U

,011

.04

.03 1.60

.04

.70 0 42

.14 .00

8 03

84

.31 10.8.8] ,U

.09 1

.OS

.04 1 70

.00

.74 '6 47

.10 ,rt5

8 97

.00

,38 10 91 1 .40

77 1

.0«

.on 1 96

.00

.79 0 .V2

.10 .71

».(K»

80

.45 10 94 .40

.8.51 I

.Ot

.07 2 12

.07

.h:* 0.5(5

.17 .77

9 01

-07

.51 10 97 .47

93 1

.00 .082 27,

.00

.87 0<V1

.10 82

9 07

.08

.58 11.00 .40

13 00 1

.Ot| .IC|3..U^

.09

.91 tt.66

.19 ,8S

9.11

.09

.QfiU.03j .49

.081

0.10 0.11 2 51

O.TO 1.06!«.7l't 10 4.94

0 14 '1.90

8,7211.05' 1.00

13.10(

.11

Ai2 m

.Til .99 0 76

.111 .Ml

9 18

.01

.79 11 08 .01

,24

.11

.MI2.7S,

.Tl 2.0:i 6.81

.315.05

0 21

.91

.8011.11 .01

.32

.11

.in2 S9

.Tl

.OS ft 85

33

.11

9 25

.91

.93|n 14 .01

.40

.14

.1H3.(X):

.T4

.12 0.i«>

.34

.10

e 28

.94

9Am\n 17 .04

48

.1«

.2o;i.u,

.TO

.16 0 95

.30

.22

9.112

.90

,07|11.20 .00

, 5< I

.10

.22 3 2l!

.TO

.21 0.99

.10

.28 9 35

.901 .14111.2311 .00

.<V4.

IT

.2i,;i 3i«

.T7

.2.5 7 04

.17

..'14, 9 ;I9

,97

.2111.201 .07

-72|

.18

.21'. 3-401

.TO

.29 7 08

.30

.40 9 42,

90

.28 11.291 .00

.80!'

.11

.2813.54)

.T9

.34,7. 13|

.39

.40

0.40

.99

.35,11.31 .00

.08|

O.iOO 3n':?.59''o.a43'2.38l7a7[

1.40

5.62

9 49

8,00

9 4211.34 1.00

13 !)fl'l

.11 .a:j:i *»Ki

.01

.43 7.22

,41

.57

9 521

,01

.49111.37

.01 14 01 11

.11

.3.> 3 7ti

81

.47 7.20

.41

.03

9 50

,01

-50111 401

.01

12 ]

.13

.37i3.H5

.81

.527 31

.41

.09

9 591

.01

.03111.431

.03

.2U

.14

.4013.0:5

.84

..507 35

.44

.75 0 02!

.04

.70

11.40

.04

28

.1«

.42 1 01

.80

.01 7.39

.40

.81

0 00

.00

,77

11-48

.00

-36 1

.10

.4.^4.00

.00

.00 7.44

.40

.87

0 09

.00

.85

11.51

.00

.45

.17

.47 4.17,

.87

.70 7 48

.47

.93

0 72

.OT

.92 ll.54|

.07

.63'

.10

..504.24

.80

.75 7 52

.40 6. m

0 7«

.00

.99 n.57

,00

.01 1

.11

.52 4.32

80

.807.57

.49 .00

9.791

.09110.00

11.69

,00

.09]

0.10

0.55 4. 3o'

OfrO

2.847.01

1,006.12

0,82'l.l0'l0.13

11.62' 8.T0

14.77

.11

.5H4 47

fl

.89 7.65

.01

.18

0 80I ,11

.21

11.05

.Tl

.80I

11

JS\ 4 ..1

91

.94|7.69

.01

.24

9,89

.11

.28

IK 08,

.71

94 1

.11

m^ 01

.93

.99 7.73

.01

.30

9 92

.18

.35

11.701

Tl

16.02 !

14

.0(1 4 tils

.043.0317 78

04

.30

9 95

.14

.42

11.73

.T4

.IDl

IS

.oy 4.74

.90

.08 7.82'

. 00

.43

9 98

.10

.5tl U.76|

TO

,19,

.10

.72'4,SI

.90

.13 7.80

.00

.40 10 (>2

.10

.57 n 79i

TO

•27 1

.17

75 4 iW

Of

.18 7 90

.07

.55,10 05

,17

.64, 11,81

.77

.35

10

.784.91

.90

.23 7.94

,08

.01 10.08

.10

.72 11.84

.TO

.431

.19

,81 5.011

.90

.28

7.98

.09

.08 10,1 r

.19

.79 11.87

.79

.52,1

0.40

0.84 5,07

1.00

3.33

8.02

1,00

6.74^0.14

iioi087'n 00 8. 00

15.00!]

1 ,41

S8 5 n

.01

.:J8

8.00!

.01

.80 in IH

111 .VM U 02 ,01 .mi Ji

.a

.yt fi 20

.01

.43

8.10

.01 - '■■■ -1

.1111.01 11.95 .01 .77 ■

,41

.94 ") 2i\

.01

.48

8.14|

.03! . .13 .wn.98 .83 ,85 11

.44

P7 '* A'i

.04

.53

8.1H

.041 H .14 .lb: 12 Wi .04 .94 ll

,40 1,01 i» 38

00

.588.22 1 .00 "-.-u M. >o

.101 .24|I2 Oi .00 10 0- ffl

.40, .01,5 14

.00

.03 8 2n' .COj .12 irj 33

.16; .31 12 on .00 U 1

.47

.iJTfi 50 .07

.09 8 30 OTI .19 m :tti

.17 .39 12.08'

07 Hill

,40

.115^, .08

.748 33;

,08 .25 10 40

10 .40 12,1)1

.00 .27 ■

40

,145 61 .00

.7918,37

.09 .32110.431

.19| .54

U, 14

.09 .30 ■

0 00 1.18^% «?!'! 10

a 84 8 4t

1 fj^ ,J.. .,'

1.10111 01

12 in

1.9ol|n 44 m

01

.21 o 73

.89 8.45,,

.111 .09

12 19

.01 5d H

01

.2r>5 7»

.9.518.401

Hi .77

12 22

.91

.»2!fl

03

. 2H .'t . K4

4 Otll8 M

-111 .84

12 24

,93

.70 1

.04

:i.' .> Ml

or, 8 5<^

.34I .\}2

12 '27

,94

70 ■

.00

.'M .'• \*rt

.11 8 00]

.30 12.00

12 29

90

.87 1

.00

.'39 *t iMt

,ni HAM

!7f> .301 ,07

12 :i-

,90

9n ■

.07

Ai n.rMJi

.21 8.fiK

.77 OTI .1.'.

12 3.'*

.97' 17 Ollfl

.08

.^7fi 11 ' 10

.'27':S 71

.78 30 ,23

12 37

981 13 1

09

1 1

.51 I Iti: 19

..j. .,

■"1 "T- •■',(•••; •*"

12.40

-1 ..|

MEASUREMENT OF FLOWING WATER

135

136 AMERICAN SEWERAGE PRACTICE

For contracted weirs, neglecting velocity of approach:
0-3.33 (L-0.1iNr/i)A

Note. — The uao of h inBtoad of H in the factor (L — 0.1 AT//) used in correcting for end con-
tractions Lb as precise as ordinary practice warrants.

For contracted weirs, head corrected for velocity of approach:

Q^3.33 (L-OANH) [(h+K) -hr]'
For suppressed weirs, neglecting velocity of approach:

Q^S.SSLh
For suppressed weirs, head corrected for velocity of approach:

i i
0=3.33L[(/iH-/i,) -h, 1 (p. 205, loc. cit.).

The Fteley and Steams formula

i
0-3.31 L£f H-0.007L

H ^(h + l.bO hf) for suppressed weirs

H '^(h +2. 05 h^) for contracted weirs

For contracted weir make L - (L — 0. INH)

The H. Smilh, Jr., formula

0 = (c.orc.)|L(2f^)V

H -{h + IJ/i,) for suppressed weirs

i^-(A+1.4AJ for contracted weirs

The Bazin formula

i
Q—mLh(2gh) (for suppressed weirs only)

m — coefficient including effects of crest contraction and of velocity

of approach, (p. 202, loc. cit.)

The Francis formulas are strictly applicable only to vertical sharp-crested
rectangular weirs with complete contractions and with free overfall and

When the head (//) is not greater than one-third the length (L);

When the head is not less than 0.5 ft. nor more then 2 ft;

When the velocity of approach is 1 ft. per second or less;

When the height of the weir is at least three times the head.

In all probability the formulas are usable with higher heads than 2 ft.,
but not much lower than 0.5 ft., as shown by Fteley and Stearns' experi-
ment (p. 207, loc. cit.).

Choice of Formulas. — "When Francis's weir settings can be duplicated or
the velocity of approach is very low, 1 ft. per second or less, there is general
willingn&ss on the part of both engineers and laymen to accept this formula
for heads for from 0.5 to 2 ft., and the same is true of the Fteley and Stearns
formula for heads of 0.07 to 0.5 ft. For higher heads the Cornell experi-
ments, which are the only guides, indicate that the Francis formula may be
used with reasonable accuracy up to heads of 5 ft.

Bazin's formula is the best where his conditions can be reproduced* and

MEASUREMENT OF FWWING WATER

137

■ if thi v«lodty of Approach is high and the height of weir low, hie formula ia
^Wlieonly uue KUtlicietitly floxihlc. For this reason it is the mo8t useful
^^^JJiDith's rocifhcionta aro the result of the most thorough study, but are
^^^pl upon experimental data of somewhat uneiiUHl accuracy. They ijo,
^^Biferor, furnish means for ftaiififactory interpolation to suit cases not cov-
ered precisely by the data which he used*

U poieible, contracted weirs should be avoided, but are often nece«sary
to inwire atmospheric pressure undarneath the nappe; if end contractions are
tmwvoidable, the Francis formuUi should be usod.

Fw rough measurements there has never appeared to be any good reason

parting from the Francis formula^ which has the advimtage «if long

land com^equent familiarity, especially in legal cases, although it has

oftan betin used far beyond the limits laid by Mr, Francis himself. It should

be borne in mind, however, that his formula apphe^i only to 8hari)-cre«ted

wm*' (page 223, loc. cit,).

tritngulAT Weirs.^The theoretic discharge of the triangular weir is
PTtn by the equation,

<? = -^-L(2c)UJ

I which Q^di^harge in cubic feet per second

t = length of crest at level of h or water surface
h = head over angle of the weir notch iu feet

Prof. James Thomson deduced experimentally a value of C = 0.017 for

Table 33. — DtficHABOE of Rioht-axglb Triakgitlar Weir.
Q»2*54 // cu, ft, per second.

« njn

ioao

0 2

a, 3 I

U 0102
0 0114
0.0127
0 0140

u mM>rti

U Uii^i

(1 (MnoO

oomt

t) muu

0.0221

0 00180

0.0240

0 002 I »

0.0200

O fN.I.'7-l

0 <>2N1

i« <«*l.:2^*

0 0.103

i« nni'.il

n n/,'j:\

i) i<uiM:t

0.04M
0.04R3
0.0513
0,0544
0.0577

0 o<no

0.0044
0 0680
0 0717
0.0755
0.0704
0.0S,'J4
0.0876

0 oom
0 rm62

0 1008
O.IOM
0. 1 103
0.1150
0 1201

0 1252
0 1305
0 135U
0 1415
0 1471
0,1529
0 1589
0 1050
0 J712
(► 177(i
0 1841
0. 1007
0,1976
0.2044
0.2115
0 2188
0,2201
O. 2330
0 24)2
O 21«1

0 4
0 2570
0 2061
0,2734
0,2818
0,2904
0.2091
0,3080
0.3170
0 3202
0 3355
0.3450
0.3547
0 3045
0 3745
0.3847
0,3960
0,4055
0.4101
0 42t#»
0.437W

0 5
0.4490
0.4003
0,4718
0 4S34
0.1953
0 6073
0.5104
0.5318
0.6143
0 5570
0.6098
0.5820
0,6901
0 0005
0 »231
0 0308
0 0508
(K0049
0 0791
0 0930

on

0 7aH3
0,7231
0.7382
0,7534
0,7688
0.7844
0,8002
0.8102
0 8323
O 8487
0 8052
0,8820
0.8989
0,9100
tJ 93.13
0,9508

0 9^85
0.9864

1 0045
1.0228

138

AMERICAN SEWERAGE PHACTICE

heads of 0.2 to 0.8 ft., in which case the formula would reduce to the foi

J

0 = 1.32 L/i

and for right-angled notches in which L—2h;Q — 2,G4 h

Experitnents made at the Massachn.'^cits Institute of Teclinolog
under the direction of Professor Dwight Porter, gave for the right-angled
notched weir,

i
0 = 2.54 A

Trapezoidal Weirs. — The trapezoidal weir differs from the rectang
type in that the sidea^ instead of being vertical, are !>uilt upon a alo|i
Usually the slope is built with a batter of 1 in 4 for the reason that at t|
angle the slope is just about sufScient to ofiFset the effect of end contrd
tions. When this is done the weir is known as the ''Cippoletti Weil
The general equation of the trapezoidal weir is as follows:

i

0 = 3 {2g) Lh

15

\ i

2z{2g) h

m which 0 — quantity in cubic feet per second

L = length of the weir at the bottom of the notch in feet

h = the head of water over the notch in feet

z = the batter of the aide or the ratio of the vertical project

the horizontal projection of the side
(7 = the gravity * 32.16

For the Cippoletti, in which 2= i, the formula reduces to

0 = 3.367 M

Irregitlar Weirs. — For the determination of the discharge over broa
creiitiMj weirs and dams having different types of crests, reference may be
had to an admirable digest of **Welr Experimenta, Coefficients, and F^
mulas" by Robert E. Horton, published as Water Supply andlrrigati^
Paper No. 200, of the U. S. Geological Survey, 1907, and to standard
works upon Hydraulics.

Venturi Meter. — The principle of this apparatus, based upon
nouUi's theorem, was discovered about 1791 by the Italian engine
J, B. Venturi, who stated that when fluids or gases discharged throu
an expanding nozzle a sucking action was* oxercimHl In the small diamot
diminishing as the diameter increases. This principle was ftrst practi-
cally applied by Clemens Herschol in 1887 in the Bo-called Vent
meter. The meter tube, which Is the portion of tlie apparatus to '
Venturi 's discovery applies, i * I in a line of pipe and cansUi

three parts, the inlet cono, in diamotcr of the pipe is grad\J

roducodi the throat or coDStricted sectioB^ and the outlet cono, In <

MEASUREMENT OF FLOWING WATER

139

er iTicreases gradually to that of the pipe in which the meter
t inserted* The throat is lined with bronze; its di;iraeter, in standard
[meter tubes, is from one-third to one-half of the diameter of the pipe;
[ and itK length but a few inches, sufficient to allow a suitable pressure
nber or piezometer ring to be inserted in the pipe at this point. The
qr or inlet cone has a length of approximately one-fourth that of the
' cone. A piezometer ring is inserted at the upper or large end of
the inlet cone, and the determination of the quantity of water flowing is
h»md upon the difference in pressures observed or indicated at thit* point
itui It the throat of the meter. The general form of the meter is shown
m Fig. 43.

' WntiiriMfttr Tub* -'
I is. \\\. — Arrangement of venturi meter on prosmirf* pipe.

of a formula from which the discharge of the Venturi
fuic- iiiputod may be found in Hyghe^ and Saflford's '*Hy-

dfmttl»G»,^ p, 116. As written by Hcrschel the form of this exprossion ia

0= «"»L^ v/2^(a;=w

atfli

\/2p/f

^Hnrtudi fitfjt ^T\^ \\w ariMJS in square feet at the upstream end ant) n\
(thr thrcmt of the meter, respectively, ^i^a the pressure heada at the
aorretpotidioft poinUtf

140

AMERICAN SEWERAGE PRACTICE

Utider actual operating conditions, and for standard meii^r tuhes^
including allowance for friction, thia formula reduces to the form

Chart /f§C0nhr Qfaf.
(Canti'/ruaffy Records

Reghtfr CauntwrDtaL
*' ' (ihows the Tafot

i^tnditaforDial.

Bastf tiinsaqitctre
80(fibs,

Chan Recorder
(CifiHrtyaiiy ffifor^

IndicotQf OiaL

(Shows fhf Pr§i€nf
ftjtf^nim.y

Bast, if4 iris^ sqvam
Ht,qht, 5 ft

^hfpptnq Wfiqhti

Fio. 44. — Type M register-indicator Fig. 45.^Typ© M indicator-re-
rerorder* corder.

The coefScicnt written (1.00*0.02) is made up of two part«, or

V Ui'— Hi*
Cj as coefficient of friction-

For standard meter tubes in which the diameter erf the throat in li^
tweeu one-third and one-half that of the pipo» the vnlue^ of C% moge

MEASUREMENT OF FLOWING WATER

141

1.0062 and L032S^ while the friction coeflicient Cj varies fram
lo 0.90* Thus the range of values of C h from 0.98 to L02, and

Airlbfygj

* Tute

'Float

Hwf'qhfi I'S"
Width r ys*"
Base ■ ZO^'MdO"
Shipping Weiqht-

4i.-*MAnonieter for ventim Fio. 47.— Type D n*gmter and chart
t«*t©r. recorder.

■ - M written above a§ (1.00=^0.02), Hazen^ thinlvS
u? for practical use, J, W. I^oux* givfts rosulU

142

AMERICAN SEWERAGE PRACTICE

of experiments made by him on a 4-in, meter tube with 2-in, throaty
which show a coefficient leas than 0.98, approximating 0,975 for ordina
velocities and falling as low as 0;915 for very low velocities, about 0.(
ft. per second, through the throat of the tube.

The Venturi meter affords one of the most accurate method.s of meas-
uring water, the registration being within 2 per cent, of the actual flow
of water at ordinar}^ velocities.

The Venturi meters are made by Builders Iron Foundrj'' of ProA-idence,
R. L, under Herschel's and their own patents. The standard sizee and
approximate cost of tlio meters, with ca.st-iron meter tubes, are shown
in Table 34, the list prices being sufficiently close to actual prices for
preliminary estimate. For sizes of 48 in. and larger it is often possible
to con.struct a meter tube at less cost bj^ using in part some other niaterial
than cast iron, such as concrete or steel plates. In the table S50 la in-
cluded as the cost of the oil seal in each case. The prices given alfl
apply for float-operated instruments when the cost of the float pip
is included.

Table 34.^ — VENTURi'a Meter Tube Prices (p.o.b. Pbovibence)
Pressures up to 125 l». per Square Inch, Including Cleaning
Device axb Oil Seals

Diameter,

Price

Diameter,

Price

inches

inches

6

$ J 50. 00

32

$ S95.00

8

J 180.00

34

995.00

10

205.00

36

1100 00

13

245,00

38

1205 00

14

285.00

40 '

ri20.00

16

360.00

43

1440.00

18

420.00

44

1570. 00

20

480 00

46

1700.00

22

550,00

48

1835.00

24

620,00

54

2290.00

26

645.00

60

2790.00 1

, 28

720 JXJ

^M^

3345 00 1

30

810,00

72

3950.00 1

Type M lmlipator-n.*c*jrder

Type M Register-imiicator-recorder
SpLMMa] ijlanimotrr
Miinocnetcr. ...

1290.00

450,00

30 00

05,00

A simUar meter, using the Venturi tube but having a dilfewnt reeo^
ing mechanii^m, has recently (1913) been put upon the market by
Simplex Valve k Meter Co. The principle of its recording device
described by J. W« Ledoux in Transactions Am. Soo. C. E.,
LXXVI, p. 1048,

wm

MEASUREMENT OF FLOWING WATER

143

lio minimum measuring capacity of the Venturi meter, in V. S,

T day, J8 approximately equal to the square uf the throat

II inches, followed by four ciphers^ thus: 4-in. throat diameter,

4 - Itjj minimum measuring capacity -160,000 gal. per day; 8-in*

OHt diameter, 640,000 gal. per day.

be maximum measuring capacity of the meter is approximately
tiH*n times the minimum capacity »

tie actual lo8» in pressure corresponding to the maximum discharge
[ ihoee nteters a^ built is approximately 1 lb. per square inch, &o that
ier operating conditions the loss in pressure of the water, due to fric-
I in the meter, i« generally not over 3-3/4 lb, per square inch. Greater
than the lii^ted maximums may be discharged through the
: _ with a loss of head proportional to the squares of the quanti-
Thus, a 24-in. meter tube (recorded in Table 3$ as cat. No,
10) hajs a friction loss of 1 lb. per square inch when discharging at its
|3dmum measuring capacity of 13 milhou gallons per day. At half
it* tlie friction loss is 1/4 lb. per square inch. Similar calculations
ic fur any other rates of flow.

Tahls 35.— Ve*vturi Meter Data for Designers

•IrtiMl

Lm&gth

Approx-
imate;
W«isht,
pounds

^-Uj*

GftOow pmr 24 houri

OallonB per minute

iTi

Minimum

MnJtlmum

Minimum

Mudmum

1

11

t ft. Ill Jit
1 ft. Wk ifi^
Ifi 7 In.

4,000
6,000
10,000

51,000
73,000
t.30,000

3

35
55
90

50

f

L
1

7(%, 41 in

2 ft 3 in.
I ft. 11! in.

7.000
10.000
16,000

100.000
I.IOXKK)
203.000

11

70
90
HO

85

m

31)

2 ft, tl in

aft. rjin

2 ft. 41 in.

10.000
10.000
2.-!. 000

130.000
203.000
293,000

11

16

00
140
205

110

♦II

411
42

3 fL lOJ In.
3 ft fl in.

16.000
26.000
40,000

203.000

343.000
520,000

11

18
28

110
240
3<J0 ;

^

m

aft. uin^

4ft. ftlio.
4lV 2 itL

26.000
40.000
03.000

343.000
520,000
S 13.000

18
28
44

240
3«0
54>5

275

n In.

* 'i JO in.

40.000
90.000

520.(>fKl

SM.OOO

l.i 70.000

28
44
63

360
665

810 1

460

t

•^1

Ml

fit. o^ln-
l» ft. 11! in
^tu 7 in

I on, 000

il83.O0O
1,373.000
2,080,000

53
74
110

680

0^0

1^440

700

144

AMERICAN SEWERAGE PRACTICE

Table 35.— Ventuhi ]

Meter Data for

Designers. (ConHnvedD

Inlet and
outlet

diameter
inches

Cata-
logue
number

Length

Measuring capacity

Approx-

Gallons per 24 hours

Oallons p«r minute^

imate
weight,
poondi

Minimum

Miolmum

Maximum

10

103i

104

105

9 ft. 41 in.
8 ft. 7 in.
7 ft. 6 in.

106,000
160.000
250.000

1.373.000
2.080.000
3.250.000

74

110
175

050
1,440
2,260

1.100

la

124
125
126

lift. Oin.
9 ft. 11 in.
8 ft. 10 in.

160.000
250.000
360.000

2.080.000
3.250.000
4.680.000

110
175
250

1.440
2,260
3,250

1530

14

144J
1451
147

12 ft. lOiin.
11 ft. 6iin.
10 ft. 2 in.

203.000
331,000
490.000

2.633.000
4.298.000
6,370,000

140
230
340

1.830
2.080
4.420

2.200

16

165}
1661
168

14 ft. 5iin.
13 ft. Uin.
11 ft. 6 in.

276.000
423.000
640.000

3.583.000
5,493.000
8.320.000

190
295
445

2,400
3,810
5,780

3.000

18

186

1871
189

16 ft. lin.
14 ft. 5iin.
12 ft. 10 in.

360.000
563.000
810.000

4.680.000
7,313.000
10.530.000

250
390
660

3,250
6.080
7.310

3.700

£0

306J
208
2010

17 ft. 11 Jin.
16 ft. 4 in.
14 ft. 2 in.

423.000

640.000

1.000.000

5.493.000
8.320.000
13.000.000

205
445
695

8.810
5,780
0,020

4.750

aa

227

229

2211

19 ft. 10 in.
17ft. Sin.
15 ft. 6 in.

490.000

810.000

1.210.000

6.370.000
10.530.000
15.730.000

340
560
840

4,420

7.310

10.900

5.700

248

a4 2410

' 2412

21 ft. 2 in.
19 ft. Oin.
16 ft. 10 in.

640.000
1.000.000
1.440.000

8,32a000
13.000.000
18.720.000

445

695

1,000

5.780
0.020
13.000

6,800

268J
ae 2611
2613

23 ft. 0) in.
20 ft. 4 in.
18 ft. 2 in.

723.000
1.210.000
1.690.000

9.393.000
15.730.000
21.970.000

500

840

1.170

6.520
10,000
15.300

8.300

289
as ' 2811i
2814

24 ft. 11 in.
22 ft. 21 in.
19 ft. 6 in.

810.000
1,323.000
1.960.000

10.530.000
17,193,000
25,180,000

560

920

1,360

7,310
11.900
17,700

0.600

3010

SO j 3013

3015

26 ft. 3 in.
23 ft. Oin.
20 ft. 10 in.

1.000.000
1.690.000
2.250.000

13,000.000
21.970.000
29,250.000

695
1.170
1.560

0.020
15.300
20.300

11.000

3210 J '2s ft. U in. 1.103.000

Sa 3213 25 ft. Sin. 1.690,000

3216 22 ft. 2 in.; 2.560,000

14.333.000
21,970.000
33.280.000

• 765
1.170
1.780

0.050
15,300
23,100

12.700

3411

34 3414

3*17

30 ft. Oin. 1.210.000 15.730,000
26 ft. 9 in. 1.960.000 25.480.000
23ft. 6 in.! 2.890.000 37.570.000

840
1.360
2.010

10,000
17,700
26.100

14.300

MEASVREMBST OF FLOW! NO WATER

14-)

TMMtM 35.—

VeNTlTBt

Mkter Data for

Desigkisrs. (Coniinutd)

%t^m^ ^ .

fioocth

.Vf(>uj<uritier rapitrity

Apprns-
imnu-

pntmct*

-rut '^

G&IlonJi per 24 houn*

Ga|lQQ0 pwr minuto

Minimum

M«xlmum

H

3fil2
3618

91 iu i iD.
as ft, I In,
24 ft, 10 in.

1.440,000
2.250.000
3,240.WK)

18,720,000
29.250,000
42,120.000

I.OOO
1.560
2,250

13,000
20,300
29.300

10.500

3SJ2

33 ft. Oin,
20 ft, 5 in,
2ft ft 2 ill.

1.440,000
2.S«J0,tMKI

3,nio.oo<>

18,720.000 1,000
33,280,000 1.7^
46.930.000 2,510

13,000
23,100

32,oon

18.700

m

H

4013
4017

4020

35 ft. 1 in,
30 ft, 9ifi.
27 ft. 6 in

LOOO.OOO
2.8i>0,Ol3(l
4,000,000

21.970,000
37.570.000
52,OOC»,0Of)

1,170
2,010
2.780

15,:«I0
2IV100
30.100

20.900

42U
4221

.^ftll. 6 In.
32 ft. 1 in,
28 ft. 10 In,

1.0«0.000
3,a40.0(X»
4.4|0,(K)O

25,480.000
42.120,000
57.330,000

1.3fl0
3.250
3.060

17.700
29.300
39.800

33.700

441ft
4418
4423

37 it. 8 in,
34 ft. Oin.
30 ft. 2 in.

2.250.000
3.240.000
4,R4O,000

20.250.000
42.120.000
52,92O»00O

1,500

2.250
3.360

20.300

29,300
43.7m)

20,400

m

401S
4«ltt
4«2d

40 ft. 2 in.;
aa ft. 10 iu.
31 ft. 6 in.

2,250.000
8,6 10,000
6,200,00r»

29,250,000'
40,930,000
tt8.770.000

1,550
2.510
3.670

20.300
32.600
47,800

29.700

m

4810
4M0

it ft. n in.
37 It, 2 in
32 ft 10 in,

2,560.000
4,QtM),00U
5.7mi.(MX)

33.280.000
52.000,000
74,S80,000

IJ80
2.780
4.000

23.100
36.100
52.00tJ

33.000

m

$017
S021
1I02A

42 fk 10 in,
:!«ft. ei/i
34 ft. 2iti

2,800,000
4,4I0,0tK)
0,250,000

37,570.000
57,330,000
81,250,000

2.010
4,310

26.100
39.800
56.400

36. 9 no

1 ^

5217

822(1

45 ft. 3tn

39ft.l0lJi.

3fift. eio.

a,8»o.r»oo

i.840,000
11,7(10,04)0

37,570,000
52.920.000
S7,8SO.0OO

2.010 1

3.300

4,890

26.100
43,700
61,000

40.700

I ^

MIS

M23

liUt. 7 In,
lift. Sin
ao ft. to in

3.2IO,fXX1
5.3d0,0OO
7,2»aO0O

42.120.000
ftS,770.000
04.770,000

2«250
a,670

5,000

29.300
47,800
65.800

44.600

1 n

M22
&«2I»

47fMlif».
4»ft. 7 in
Sllft. 3 in

3.510.000
7,840.0(H?

40,030.000
bH,770.(K>l>
lUl.i»20,(KX}

2.510
3.670
6,440

32.600
47.8f)0
70,SC0

49.000

63.400

[

II
m

ft»19
1 W»39 !

Mfl, 4 in
H ft. n in
lu ft, 0 In.

s.eio.otio

5.7eM).CifM)
8.410.c:NM>

4rt,03O.00t»

n>9.;iao,<xM>

2.510 '

4,000

fi.840

32.600

.■iy.ooo

75.1KW

IQIO

im

M ft. 6 in
lA it. .1 Irt
iO ft 10 in

4.(Ki0.oo(»

«.250,f><K>
O.OOd.dniJ

52,rjOO.(HX»
H1,^,S0.<MX>
117,000.01)0

2.780
4,340
6,2,'iri

30.100
50, 4 f 10
81.300

68,300

146

AMERICAN SEWERAGE PRACTICE

DirectioES for installing the Venturi meter tube arc given by
Buiiders, Iron Foundrj^ aa follows:

*'The Meter Tube is set m the pipe line in the same manner as ordinary
pipe, the shorter cone forming the inlet, or upstream end, A notch in the
etige of each flange denotes the top. It is not eaaential that the tube be
horizontal; it can be inclined or vertical.

A straight length of pipe of the same di&meter as the meter tube should
immediately precede the inlet and contain no gate valve or other fitting
liable to disturb the smooth flow of the water. The length of this pipe
should be at least six times the diameter of the tube for sizes up to 24 in-
and at least 13 ft. for larger sizes. If the outlet end of the meter tube is of
different diameter from the pipe line an increaser or decreaser should be
placed at this point. It is unnecessary to have a straight length of pipe on
the outlet side of the meter tube.

For standard installations both meter and instrument should be set at a

^^^^^^^^^^^^^ ^^^^^H^^^^^^^^^^^

1

■BP=1

P^y^^^^K^^Bk^' l^^^^^^^^^^^^k^

KiG. 4S, — Inkt cone and throat of large venturi meter for scu^gr

point where the working pressure is at least 12 lb. per sqii&re inch. Fr^^
quently, however, this requirement may be modified after consultation witJ
our Engineering Department.

Two ("imail pressure pipes connect the meter tube with the instrume
These can be brass, lead, lead-lined or other non-corrosive pipe, 3/ 4 in. diama
ier if the length is 50 ft,; 1 in. diameter Jf the length ia 100 ft., etc., and <
nection should be made at the aide of each pressure chamber. The pipii
should have a pronounced up or down grade^ contain no summits or dc
siona where air or silt might collect^ and a valve (or corporation cock) i
Imi placed on each pressure pipe close to the nielcr tube. If a
depression is absolutely unavoidable^ a blow*olI valve should be prpvide
mi such point All joints must be perfectly tight and the piping properli
protected from froet,"

Tht; fon^going paragraphi* r
metfT for 111* .jsuruli! wtvtfT. l-i-

MEASUREMENT OF FLOWING WATER

147

) be lueasurcd, but on account of the suspended matter in the
mwM^, which might clog the tubes and interrupt the operation of
thie nsigiaterr it becomes necesBar>^ to adopt special precautions or use a
moMnriifti diiferent pattern of instrument. Fig, 48 shows the inlet
cone and throat of a large meter especially constructed for measuring

It will he noted that at each annular chamber or piezometer ring there

TiUvac by wliich the pressure openingj^ can 'be dosed, and these

are so designed that in closing a rod is forcefl tlirough the opening

to dean out effectually any matter which may have clogged it.

pen all four of these valves have been closed the plates covering the

•** Oil «eal and register, Ward Street Pumping Stiition, Boston.

■ prcHsare chamber may be removed and the chamber
tA* i; 'ftith hose or otherwise.

In urdtT Ui prevent the interference with the operation of the register,
t>y doitgitig, nn oil seal Is inj*ertetl in the pressure pipe» between the
iiwter tube and the register* The pressure is transmitted as far a^ the
•*'"' ' ^vtiter in the pressure pipciJ, and from the st^al to the register

*^ Thus it \» impossible for any sewage to get into the register

^ with its jiroper operation. 8uch an oil seal is shown in

' v.uli illustrates the apparatus at the Ward Street Pumping

A the Metropolitan Sewerage Works.

*M>ti metsiirements of tlie flow in sewers are rarely made except in

UMil

14S

AMERICAX SEWERAGE PRACTiCE

rf ttce floa^H

iQClaiQgiilar chftnnieb or for the approjomftte delcntuitatioo of the
locitj of flov beCureen two manholes; but in ffUidies of tidal etaircnls or of
K«7ig;e ciErranto in bodks of vialer into wliidi sewBiie n^
flosti are mmrcfwHy cmpkyfed.

Three t jpee of floeta mmj be ttsed — mafmioc ioati^ stibntrfaea floata,
and rod or ipar fioata. Onl v aorface vdodties can be obtaimed
use of surfaee floata and the resulta can be oooBdered only as i
iiMitininii, owing to tbe modifying effects of tiie wind. Subeuifaee I
emnsl of relatively large bodies aligbtly beairier than water, <
by fine wiree to einfaoe floala of aufficieot siae to fumisli tbe oeeeeaary
flolatioo and eaitytng markava by iriiich Ibeir eounea may be timecd*
Tbe reavtanoe of tlie upper float and eomieeting wire is g^vMraOy 00
riig^t that the combinatlop may be aeBiiined to 9«nre with the velocity
of the water at the poeitioo of the submeiged float. Bod floata haf
been tieed for measnrixig flow in open flumes, with a hi^ degree of aec
racy* Tl>ey generally oooast of metal cylinders 90 loaded as to
Tfftically. The velocity of the rod haa been foimd to eotieafwpd
doaely with the mean Telocity of the water in the ooufBe followed by thifi
float. I>etailed descriptions of the me^hoda of mahing acotrate mcas-
arementa of flow in rectangular flumea may be found in Francis' ''Lowell
Hydraolk Experiments" and in Hu^es and Safford's *' Hydraulics."

Current meter gieaatuementa may be employed for the ace
determinatioa of the \*elocity of flow in sewezs of considerable siae or b
open channels, provided there be not too much paper or other su^^end^
matter likely to clog the met^. The cuirent meter must be ealibrat
tiy moving it at a uniform speed in stIU water. Knowmg the <
or rating of the meter, the average vdoeity of the water at the
where it is held may he ohtained with a high degree of arcuraey.

Gagti^^ of flow may be made by sercial methods, theone-point mctho
the two-point method, the multiple-pomt method, the method of int
gating in sections, and the method of integrating in one operatioti.

In the siogje-potnt method, the meter is usually held at 0.6 of tlie depti
and In the center of the stream, and the result is assumed to indicate I
mean Telocity of the stream* This is but a rou^ apprnximation, i
able only for hasty obeerratioos with no pretense to aecuracy.

In the two-point method* the Telocity is observed at 0^ and 0.S of (
depth, and the average of these two figures is taken to represent
average velocity in t be Tertteal erctMO . The stnam can be cii^idid ia^
a number of vertieal seetiona^ and the a^-ernge velodty in each '
mined approodmately by this tfielhod.

By the multiple-point meth - t^ach of a largo number

of potnte, each repn»eiitine t ' ,. ,.^areaofthei

tion of the stream, is det* \ad the average of the observed

lodtios b then tlie mean vcioctiy m the sectiott4 Or, the vatoeitiaa an^

MEASUREMENT OF FLOWING

149

t a large number of points and lines of equal velo^^ity in the
m are then drawn and measured by planimeter; by utilizing
_Uie method employed in computing mean elevation of a given area from
i ecmtour map the average velocity may be found. The emplo)^nent of
method assumes a condition of steady flow, not only for the whole
iy of water but also for each filament, since it is obviously impossible
► oliserve simultaneously the velocities at all points in the cross-section.
By the method of integrating in sections, the cross-section of the stream
di%*ided into a number of vertical sections and the mean velocity in
I is determined by lowering and raising the meter from top to bottom
ack to the top of each section, at'a uniform speed, for each observa-
. This is usually the most accurate and satisfactory* method of
ing ordinaiy current meter gagings.
In integrating in one operation, the meter is lowered and raised as in
ing by sections^ but at the same time is moved in a horizontal
J across the stream at a uniform rate. The result is intended to
show Uie average velocity of the stream at one operation. With a skill-
ful oi>enit<ir, results of a high degree of accuracy may be obtained by this
I method, and much more rapidly than by integrating in sections.

In a masonry conduit of regular form it is possible to make Integra-
Xium in one operation by means of a track-board and pivoted sleeve, by
which the meter is guided so as to pass over the entire area of the section
of the aircara, and if it is moved at a uniform speed, results of great
tccTinei' may be obtained in this way. This method is employed in
Pv*! '^')W in the aqueducts of the [Boston] Metropolitan Water

^1 1 I ILLS been described in detail by Walter W. Patch in an article

entillttd ''Measurement of the Flow of Water in the Sudburj- and
Ccichituate Aqueducts/' in Eng. News, June 12, 1902, p. 488»

An excellent discus^iion upon measurement of flow by meter observa-
^otu» will be found rn Hughes and Safford's '* Hydraulics,^' and in Hoyt
*iiilGruvcr*« " River Discharge," 1908. The subject is also treated by
Jt»lm Clayton lloyt and Nathan Clifford Grover m certam of the ** Water
Sttpjily Papers" of the U. S. Geological Sun^ey,

ri^ilte

CHAPTER V
QUANTITY OF SEWAGE

Much information relating to the quEuitity of sewage likely to be, i
actually being, produced by muntoipalities has been published in varii
papers and reports. As this quantity is a fundamental factor to
considered in the design of sewers^ intcrcepters, pumping .stations and
treatment workii, an effort has been made herein to bring together so
of the more significant data and to set forth some of the <^iin^litj
influencing the volume of sewage*

The qmmtitj' of sewage which must be provided for may be confide
as made up of definite poilions of,

First, domestic and manufacturing sewage^ derived primarily from i
public water supply carrying the waste products due to modern dome
and industrial conditions;

Second, manufacturing wastes not originating from pubUc water supp
consisting of certain quantities of water procured from other sources »ti
as wells, rivers and lakeS; which will be defiled by the processes in which
they are used;

Third, the water which finds its way into the sewers tlirough infilii
tion and which is either ground water^ as ordinarily coriisidered or (in ck
proximity to rivers) may be water filtering through the ground from ]
and

Fourth, rainfall immediately collected and called *^ storm
this bi treated m Chapters VI, VII, VIII and IX,

Ah it is desiraljle in designing sewers to provide for the future, eatu
of population become necessary in order to ascertain the total aniountj
sewage of the first three classes for which the sewers must be proportioc

POPULATION

It is impossible t.o forecast precisely the population of the city at i
definite time in the future or the rate at which the city wdl grow. Hd
ever, a considerntioD of the growth of a city in the past^ its location (
natural advantages, together with a study of the past growth of otl
cities now of greater size, tnakes it potiisible to prepare a logical e8tim|
of the probable future rate of growth.

The present population, if do recent census has been token,
be estimated in a number of way^. The mQ»i obvimu method

tm

QUANTITY OF SEWAGE

161

\ Mm\nm that the rate of j^rowth has been uniform and the tame aa that

I bptweea the two most recent census enumerations. Where the number

of "ftswessed polls" b known, it is possible to obtain a fair approximation

o! the total population by multiplying this figure by a factor obtained

by comparing the number of '* assessed poUs" with the population in

pant ccmjus years. Other factors of similar character may be obtained

by usa of "school censua" returns, the number of voters at recent

f\ti' 1 -^ number of names in the Directory, or Post Office or

P<|- rtment counts. None of tho.se methods is, however, of

fETP4t voluo m itself but may be utilised to confirm, or aid in forming^ an

«'rtinlat<^.

The future population may be predicted in a variety of ways which are

1900 I9M BK

TMm 09**% Apfly 1o HrtffOuKM 4^)r,

Fio. 50, — ^Growth of large American citiei.

toone or bga logical, and if employed with care and the data used in ap-
T'^yiugr tht^iri tiTv norrort, the restUt^ will probably average as close to the
^^h !i8 it is reasonable to expect such prophecies to be. The degree of
'^'''"Jinwiy i* sufficient to enable a sewerage system to bo designed w itli
to meet the rec|uirements during the term of years for
dt and yet not be of such gi-eat capacity that it thrown
^ I rianciai burden on the community. Those methods of

^ ■' ^ in population are:

I that the ratt* of growth between recent census enumera-
'*^i>- HUi rciiiiAUi conistant for a considerable niunber of years.

152

AMERICAN SEWERAGE i'RACTICE

2. By asstiming that the rate of growth can be shown graphically
plotting a curve through the points representing the population of
city at different dates and then eoctending this curve mto future y<

3. By assuming that the rate of gro>\i:h will show a uniform arithmetic
increase from one census year to another,

4. By assuming a steady decrease in the percentage rate of inc
the city grows larger and older.

Assumption of Uniform Rate of Growth- — A prediction of the inti
in populiit ion, i;>aacd un the assumption that the rate of growth be
recent censas years will remain uniform for a considerable future period,
ia shown liy line A in Fig. 50. Tiiis undoubtetlly gives in many cases,
particularly whore the communities are young and thriving, resulta
which are too large, as indicated by the records of urban developmen
In view of this fact, the approval of the methtxl contained in some of ti
early treatisejs on sewerage is an indication of the slight basis of facte
which the plans made then rested. For example in Baldwin Latham|
*'Sanitarj^ Engineering," edition of 1878, the following advice isgiveii|

** The mode usually adopted in approximating the future population,
to asoertJim what has been tlie prospective rate of increase for a number (
yeans back, and by making the same, or, ia some oases, a greater alio wand
for incrcjLse in tfie future^ so to calculate what ia Ukely to be the probafa
population in years to oome, In some districts this mode of estimating 1
poptiiatton has been shown to be liable to error, as there are distriots, such \
manufacturing or suburban districts, located netir large cejiters of populatio
which are liable to rapid rates of increase, and la some cases the populatla
of partiGular manufacturing and mining districted has been found to decline,!

This method waa a favorite one in Germany down to about IS90, whq
it was discovered that many of the large cities which had increa
uniformly from year to year from 1870 to about 1887 or 1888, had sudden
begun to grow at a much more rapid rate. Munich, Leipzig and Cok
showed this change in an astonishing way. Until this rejuvenation i
place, it was customar>^ to predict the growth of German cities by
formula, P = /j[1 + (//lOO)]" whereP is the population after n years haii
elafjsed, -p is tho' present population and / is the armual ijorcentage (
increiise in the popidation which has been observed* Pi
growth of many of these cities could be satisfat^'torily i
straight lines down to 1887* The gro\^^h of the population of the Londa
metropolitan district from 1841 to 1801 was about 20 per cent, cvc
decade, whereas the decennial rate of growth in Berhn and its suburbs h^^
been more rapid and, as is to be expected in n
meut in population, industries and commcn rra

been erratic, like that of many thriving American n
of ostimatmg population by a uniform rate of increase • i

QUANTITY OF SEWAGE

153

hlile m the caae of large and old cities not subject to periods of g;reat

cir iiiclustrial artivit3\

^ Onphical Method of Estimating Futxire Populatioii.— The information

irnUhM by diagrams of the past growth of cities is ver>* instructive, but

apt to predict the future growth of a city from it*? pa^st develop-

rxiending the curve of that development^ is likely to give mis-

; result**, as will be shown later. Diagrams have a u.seful place in

Jati ilmly of changes in population, but they are not a substitute for an

^caligation of the various influences which have affected the city's

ffih in the past and may affect it in the future.
^ Anthisettcal Iccrease in Population. — ^The method of predicting future
which is carried out by assuming that the increase from
lecndc is an fu*ithmetical rather than geometrical progression
pves the straight line shown in Fig. 50, line B. An instance of the ure
I ihiJ* mcthorl was in the preparation of the estimate of the population
[ the Borough of Manhattan made by the Board of Water Supply of
flirk City. According to this assumption^ the arithmetical increase
ouie nil when the population reaches 3,0O0,0(>0, the entire subse-
at growtli of the city taking place in the other boroughs. Dr. Walter
intimated in 190S that New York's population would increase
arithmetical rather than geometrical progression, basing this
DO on the relative growth of New York and the whole countri%
Amhy distribution of future immigrants, and an increaaing west-
l twtnd of the countrj^s inhabitants.
Becretse in Percentage Rate of Growth as Cities Increase in Size. —
AMc<*ncrai rule it is found that the larger the city becomes, the smaller
bo tlie porcentage rate of growth from year to year. From the
ilition of the riites of growth of six of the large cities of the countrj',
r*ble 3ft, it is apparent that this reduction in the percentage of growth is

Tmut 3$. — Average Rate or Growth of Citie s, at Various STAOEa
or Growth

iol Hly

XX)
MJO

1 PhlLi-

I ddpbw

39 6

44 6

51 3

39 7

27 4

20 0

21 r

,,.,, 2

P»*rn-ai«ijfi rule of f^rowtb p«r 10 your*
Balti- \ Cincin
more ' tmti

8t,
htniJM

loa.i

76 9
21 5
26 9
24 I

Boiion

45 5

44.6
33 . 3
24 5
14 9
»I7 r,

iWAukee

53.3
28,1

2H.7
20 3

52 1

2ro

70 0
41 0

- btt«»<l oo iiMiiinofl uiiK *

Aver-

mjy

42 7

33.2
27.8
22.1
IS.S
17 7
'17.0

I b«lw««D ecu'UB pn^tiodMt

154

AMERICAN SEWERAGE PRACTICE

Table 37. — Rate of Growth op Cities frou Decade to Decade

Cities between 100,000 and

aties between 200,000 and

Decade

200,000

400.000

Number

Rate of
increase

Number

Rate of
increMe

Per cent.

Percent.

1840-1850
1850-1860
1860-1870
1870-1880

2
4
6
6

39.5
33.6
63.2
34.8

5

29.6

1880-1890

10

48,7

6

24.0

1890-1900

11

28.7

12

26.3

1900-1910

13

31.5

12

20.3

f t

Population

Fig. 51. — Relation of rate of growth to population.

Upon Fig. 51 have been plotted the rates of growth of several of the
large citie-s of the country, showing the ratio of growth to population when
they had a population of from 100,000 to 200,000; 200,000 to 300,000, etc
The marked tendency toward a reduced percentage rate of increase is
clearly .^hown in all causes. The heavy solid line shows the average ten-

QUANTITY OF SBWAOB

155

r

dcncy of all and the heavy dotted line the average tendency of all except
<ew York nsiA Brooklyn,

Tahuc 38.— Kate of Growth of Amkrican Cittjjs in 1900-1910

tl^Tuiuoi

^«w Eag Unci

Clli«M over 100/KlO or more ia

Oitiei ol 25,000 to 100, OOU m
1910

Ko.

AgKr^CStQ populAiioo

1910

1000

In.

per
eent

AsKV^CBte poptiJflitiaii '

lo-

NdJ

1910

1, 606,9 J14

8,599.877

4,761.966

,575,{W»H

1,172.021

5&9.082

S3D,075

2t3,3Hl

1.435.0W4

1.637,0g7

3.110.7S2

1,553,809

80U931

712.387

380,285

3;$0.995
207,688

lOOO

eeat.

128,527

8.241.0781 6.970»518! S7.ll

Territory rural in 1910

1,097,336
5,592.519
8.633,350
7JG4,205
9,102,742
6.835,572
6,827,078
l,tt86,006
1.809«975

1,102.486
5.146.961
8,637.570
7.324,759
8,105,763
6,361,352
5.370,6tW
1,099,325
1,236.045

-0.5

8,7

6.0
12 3

7.5
27 1
53 4
40 4

49,348,883 44.384.930 i 1 . 2

growth of Chicago has been m exceptional that it has not been

diulcil in Fig. ol and it secerns probable tliat the growth of New York

l^lttid Brooklyn ha8 ahio been so abnorxual tliat it ib hardly safe to bade

I i^es in which they are included. The result

, cur\'e E, Fig. 51, which shows, based upon

[ pMt exiwrience, the average rate of increase in populatiou which may

[^«|iceted as the cities increase in size. These results also appear

t Tiibk 36; the mte of growth shows a gradual reduction from 60.6

s iug between populMionf^ of 100,000 and 200,000,

H •H'owing bitwecn populatioiw of 800,0041 and

An irL«tru« u\ •' latHc Mijuwuig vrif vanatioQ in the rate of increase

|tt«tito i»f dilfrrrnt .•'izcg in different partes of the country, between

been prepartKl by the U, S. Bureau of the Census

LH Tabic :i.S. It show8 clearly that local influence!* are

156

A Jd ERIC AN SEWERAGE PRACTICE

great importance in determining the rate of increane of Arocriran
Ities.

Decrease in Percentage Rate of Growth with Age.— In luidj-

tion to t ho tendency toward the reduced rate, of growth as cities grr>v

larger, there is also a marked tendency toward a decr^^ksed groHih ^

the uation grows older. In other words, the rate of growth, as a nile,

for cities of similar sixe, was less between 1900 and 1910 than letwcen

1870 and l?i80» as shown by Table 37. This is aL*o true of the populiir

tion of the entire coiintr>% specially during the last half cent 0/31% a^ showo

by Table 39. Making the corrections suggested by the Census Burwiu

fur the population of 1870, it appears that the rate of growth of tb

country has decreased from about 35 to 21 per cent, in 100 yeara, iJ-

though the actual growth in numbers during this time has increased

f rimi decade to decade.

TaULB 39— POPCLATIOBT ANI> RaTK OF GrOWTR OF

Ukited State*

Dnle

Populaticm

Growib diirixut d«caide ]

NumetiMl

1 Per eent

17^0

3,52a^l4

ISOO

5,308,483

1.379,260

3,51

1810

7,230,881

1,931.398

36.4

1S20

9,638,453

2,308 572

33 I

1830

12,8<3€,020

3.227,567

33 5

1840

17,069,453

4,203,43:1

32 7

1850

23,191.870

6,122,423

35 9

IS60

31.443,321

8,251,445

35 6

1870

39,818,449»

8,375,128

26.6*

1H80

50,155,783

10,337.3:H

26 0

1890

62,947,714

12,791,931

24.9

1900

75,994,575

13,046,861

20.7

1910

91.972.2G6

15,977,691

21 0 ^

• Ccntii* repofU rUiim « deficiency in enumerattoo of Suutberti sCnU^a (or l>v7U.
Th« Ceiimis Uuroau jeive« e«tim&UHl populaiioD and percefit«c« »9 tit«fr«d. Tlui v^
popuUtiud «« rtriumed tor 1370 wm aS.558,371.

Probably the best result to be derived mathematically may be ob'
tainecl by assuming^ in the light of the statements previouHly given, i
dtcrea^ing rate of growth as time goea on, taking into cou infl

sixe of the city at the end of each decade. Such tm estimiii " ^^

Fig. 52. One of the most frequent and useful methods is to base the
prediction on the experience of other cities which have already rcucW
and paj58ed the present population of the city under considcratJoiL
This \s fione, a^s sho^Ti in Fig. 50* by arranging tlie lines indicating th«
change in population of different cities m that wlien ili^' have rcftcM
the present population of the city under coiLsideration, they all pMi
through the same point. In this way their behavior after paasiug thii

^SgL^^^HL

W QUANTITY OF SEWAGE 157 ^^H

P^^P^tic^n may be directly compared. This method may give reaulte ^^^|

Wnumrhat too high as comparisoQ is made with the paat growth of cities ^^^H

flnd^ u already pointed out, there is a tendcncv as time goes on for the ^^^H

me of mcTDase to become somewhat smaller. ^^^H

ll 10 usually desirable in such studies to investigate the growth of other ^^^H

- fiti&»in the vicinity at the same time as the growth of the city under spe- ^^^H

H aal consideration, for the information thus obtained will generally reveal ^^^H

H toy local pr^culiaritics in the increase of population. For instance, in ^^^H

Btti invcsrti(?ation of the sewerage problems of Fort Wayne, the authors ^^^|

n dflri^ nee from a study of the growth of Indianapolis, Evans- ^^^|

B villtv 1 ute and South Bend, as well as Fort Wayne. In the case ^^^|

■ ^^

■

/

100 ^^H

^

7-

h

/

■

—

^!

^/

J

■

V

r

J

4

tfj

mi

m^

—

^rf«r

f

A

CtT

r'

iri

f—

imrt^ifift

Vjman

y

iV/f9

-* —

— ^

^

"■■m^i-

tm^^ntxfHfyevn

■rfF
■ la

1

'itc
K i

i

» *« %S -70 tj75 W 'iS '% % 1300 OS KJ lb M (5^5 3C 3S 1340
Yeori

Fia, 62.— Growth of population of New Bedford*

iburg, Maas*, helpful information waa obtained from a st
^h of Salem, Chelfica, Taunton, Haverhill, Newton, Brc
, Pittdleld, Quincy and Everett.

tie in Area.— In entimating the probable quantity of s
id©<l for by intercepting sewers, it is important Ui tal
'Mti probable increase in the ai-ea 8er\^ed by sowerB and, hi
Ke prolmbfc increjisc in arci\ within city limita Such e
if area m ' '^ and sudden increases in population,
latkipii! *j the overtiixing of intercopters duri
fw which they were intended to be adequate. Furthermor
» in artsa roquire long extooaions in main sewers and may

N^wage ^^^H

n large- "^^^H
the ^^^H

AMERIi

in greatly increaaed quantities of ground water made tribuf^y
interecptcrs. Where the community ia acn-'od by combined sewers,
there b ulao the probability' that for considerable periods in the future,
or uutil the population becomen quite dense, brooka wiU be turned into
the truak sewers, thua adding materially to the nominal dry-weather
flow of sewage. It ia al.so of vital importance to riotisider where the
estimated increase in population will occur in order that the lower sec^
tions of the intercepter may be plaeed at elevations from which it w*ill be
possible to miike extensions into new territory' that may become popu-
lated within the period for which the interc^^pt^r Is designed.

An interesting illustTation of increa^ in area by annexation is furnished
by the growth of Cincinnati in recent years, shown in Table 40, coni-
plied from data published in a general report on the disposal of the
sewagn of Cincinnati submitted in 1913 by H. M, Waite, H* S* Morae and
Harrison P. Eddy.

Table 40, — Axntocations to thk Cittt of Cincinnati, 18l9-19ia

Datv of

ArB» annexed

ToUl iirea

Date of

Area ftnnexed

Total •nw

■nnexation

(fl iuiir« miles)

(riui^ra milm)

KnncxatioQ

iaciuiirG miles)

(■qu»rc milm)

1819»
1849

3.00
5.93

1 i9o:j

19(J4

5 13
0 47

41 96

42 43

2 03

1850

0 23

fi.16

190.5

0.59

43 02 '

18,55

0.77

6 93

1907

0.48

43.50

1870

12.12

10,05

1909

0 aj

49,53

1873

4.48

23.53

1910

0 73

5026

1889

0.20

23.73

; 1911

16.03

66.29

1896

11,38

35 11

1 1912

2 45

68 74

1898

0.16

35 27

' 1913

in

69,85

iwa

1.56

36 83

1 Oricin&l city qI Cindnjuti; inoorporfttod u m towo in 1802, a« m d(y in 1819

There is a marked tendency at present, doubtless encouraged by
constantly improving transportation faciUties, for the inhabitant.s of
cities to move into suburban districts. Thi« condition teniis toward
a lower deui*ity of population^ although it is more effective iu re'
the probable increase in density than in diminishiui^ existing d<i
Aa the suburban areas become more thickly populated, tlie improve-
ments of the cities are desired there and are ultimately demanded.
To secure these, it often becomei* necessary for «ubiu*ban district*^ to b*«
annexed to the city, thus eotendinp; the city limits* It is rea«<r
therefore, to expect a city to increa^ in area as well as popuL,-i~,-,
In making studies of the future sewerage needs of Fort Wayne, for
instance, the authors e**timat^^d that the area would grow from 8.6
aquaro miles in 1910 to 17.3 wjuare miles in 1950* In a nuuibcr uf ptnicoi^
munioiptLl Uiundaries have been ignored in water supply and a6WQiiM5<^

QUANTITY OF SEWAGE

159

Iciags, m at Boston, Mass., and several sections of the territory
Fihtwl Now York.

Xhid tendcnoy of large cities to develop by the absorption of adjoining
unities, or by the delegation of full authority over certain das.«H3S
nir * H to commissions acting for the entire district served, has

J of the Census to pay special attention to municipal di^-
becau^ '*iii nonje cases the municipal boundaries give only an
idea of the ]>opulation grouped about one urban center j in
f many cities there are suburban districts with a dense popula-
leutfiide the city limits, which, in a certain sense, arc as truly a part
^rfthe city as the districts which are under the municipal Rovcrnment."
PilO census nhowed that in 25 such metropolitan districts, the
percentage of increase in the cities during the last decade had
l'33.2 j>or cent, and in the suburbs 43 j>er cent. But these average
are extnimely misleading when used as a guide to the develop-
jomi of the smaller metropolitan districts, Viccauso they are greatly in-
ueawtl by the gro^vth of diJitricts with more than 5(K),000 population,
! location and age of a city are of much influence on the develop-
lOf itM Huburbs as well as of itself. For exiiniple, Providence and
had aliout the same population in 1900, but the development of
evidence metropolitan district in the following decade waa only
9A pcsr csent, while that of the Detroit district was 57.1 per cent,
[lorci the development of the Providnnce suburbs was more
! tlian that of the citVi whcre4is the development of Detroit waa
ifaiOtft wholly in the city ]>roper,

Dmidtf ol Population. — ^The a\'erage density uf population varices greatly
ill different cities, as is shown in Table 41. In designing sewers for a
Boniaiunity it becomes necessary' to estimate the probable distribution of
lion within the city. Tliis is largely a matter of conjecture, except
j sNiUowi of grcate-st age, as the density may ybjj from 2 or even less
} in outlying districts to 150 or more per acre in the mast densely
I fiOLTtM of some large cities. The New York Metropolitan Sewerage
estimute« that the future density of population in the part
Itaii which draim* into the Hudson River from the Battery
I Hiirtem River will be 306 persons per acre; that of the part of the
[ ihct Bronx dniining into the Harlem River will be 239 persona
nd that of the dLntrict draining into the Lower Ka^^t River will
pi^r a<:re. The probable lowest density in any district,
.:i be in the territory draining into the Upper Eti^i River.
( were obtained by taking the probable population of Man-
" ■ n as of 11)00; Queens as of 1950 and the Bronx as of
", the flianuter of the various parts of a uit>^ changes,
I of the present decade niay become the commercial or
jfict of the next decade, or the change may be in tho

^^

160

AMERICAN SEWERAGE PRACTICE

TABhR 41.— Statistics of thk 50 U. S. Cities of over 50,000 PopulAI
HAViNQ the Greatest Density of Population. (Compiled
FROM Financial Statistics of Citikb, 1910,
Bureau or the Census.)

fl

City

Population
1010

Dtnaity, perantim | Area laud surface »it

per acfft I in city limiii*

I»10 1900 ! 1«10

Hoboken, N, J

Jersey City, N. J...
Somer\'ille, Mass. , .

BaltiiiMjre^ MJ

Boston, Mass. , . , . ,
Xew York, N. Y.. .
Paasaic, N, J. . . . . , .
Cam bridge, Mass. . .
Milwaukee, Wis. . . .

Altoona, Pa

Paterson, N. J-. _ .

Refuting, Pa ,

Chariest* in I S, C

Newark, N. J

Trenton, N. J.
Wilmin^tun, Del. .
Bayoane, N.J...

Camden ^ N, J

Wilkei^Barre, Pa.. .
Ijawrence, Mass. . . ,
Pittiihurgh^ Pa.,. ,

Richmond, Va

Johnstown, Pa. . .
Cie\ elands Oliio
Philadelphia, Pa

Chie^gN, III

HurrLsburK, Pa , .
Providonoe, R. K.
Norfolk, Va... ....

Detroit, Mich

Alletitown, Pa. . , . .
St. Louis, Mo, .

BufiFalo, N. Y

Covington, Ky.. , .
Louisvillej Ky
Rochester, N. Y. . . .
Evannville, Ind. . . .

Savannah, Ga

.Schenectiidy, N. Y.
San Prancison. C^ .
Columbua, Ohio. . . .

70,324

267,779

77,236

558,485

670,585

4,766,883

54,773

104,839

373,857

52,127

125,600

96,071

58,8:33

347,469

96,815

87,411

55,545

94,538

67,105

, 85,892

533,905

127,628

55,482

56n,<563

1. 549.008

2,185,283

64,186

224,326

67,452

465,706

51,913

687»(r29

423,715

53,270

223,928

218,140

69,647

65,064

72,826

416,912

181,511

85

71

32

25

30

40

29

26

27

23

26

19

26

13

26

23

25

22

25

23

24

20

24

20

24

23

23

21

22

16

22

19

22

13

21

17 !

21

16

21

15

20

13

20

28

20

15

19

17

19

16

19

14

19

17

19

15

19

16

18

16

18

21

17

15

17

14

17

24

17

16

17

14

16

H

16

18

15

n

14

12

14

pj 1

830 0
8,320.0
2,600,0

19,290,0

24,743,0

183,555.0

2,069 2

4,014 3

14,585,8
2,114.6
5,157.0
3,965.0
2,406 4

14,826.0
4,490.0
4,026.0
2,577.0
4,474.5
3,233.0
4,lS,'i.O

26,510.7
6,388,0
2,723.7

29,208. g

8:1,340,0

117,793.1

3,402,8

11,352.2
:i, 576.1

26.102.0 I
2,856.4 I

39,276.8]

24.791 0|

•i,i»s:i.O|

12,S76.3
4,460,0
4.053.0
5.n<XJ.0

13,017.8]

QUANTITY OF SEWAGE

161

fait 4L— Statistics of the 60 U, H, Cittkb of ovek 50,000 Population,
OAmtro Tn« Greatest Deswtty op Populatiok. (Compiled
FROM Financial Statistics op Cities, 1910,
BuRKAr OF THfc Census.) (Contimied.)

r cu.

PopuUtioo
1910

per

t pcfsiona
Here

Arcft Iftnd surfjic« wilh-
io city limit!!, aorM.

1910

mm 1 1910 1

^B^^pcM't, Conn

jHl. Mm.,..

EBgPS lUut«, Ind

Iftr Bftreu, Conn, ...

Jkyton, Ohio

^Youni^town. Ohio

100,253
102,054
106,294
89,336
58,157
137,240
133,605
116,577

14
13
13
13
12
12
12
12
12

14

U
13
10

11
10

9
13

7

6,914 0

7,906.0

8,308.0

6,943.0

7,828.0

11,083 6

11,460 0

10,061 0

6,606 8

[ A'iliL-'^ltie riiw9 ftiQW «o upparoni dr<;rcaae iu deuMiy niucc 1900* due to the aDaexa*
B of bnt srota ol »di«e«!iii territory.

character of the popuJation from the section containing the homes of
poaple of considerable meatus to u congested tenement diirtrfct. Those
eiicos may result in increasing the density, causing it to remain
rly stationazy, or even decreaaing it ia some easea.

of the growth of different wards in Bost-on during 15 years
I dOfne factw wliich may aid in predicting the growth of other cities
' «mi[jir chfiract^r. The ^atiatios are given in Figs, 53 and 54 and in
Table 42, The city may be divided for this purpose into ouUying sparsely
•Uled r«^onK, gotxl nvsidential districts, fairly densely ix)pulated buiii-
'^©•i^f lorcial districts, and cheap tenement di^rict^. The in-

*Wait I I y of tlie sparsely settled districts, wards 23, 24 and 25, was

*^ idow. amounting to only 1 or 2 persons per acre i>er 10 years. When,
»0»r*i^ * (liHtrictf* became fairly well built-up and desirable resi-
^lAiiL , with densities of about 20 to 25 per acre, the increase

boQunt} rapid, atnounting for example in wiirtls 20 to 23, to from 5 to 13
I per acre per 10 years. The lodging house districts and business
ioiyi of tho3e in a transitory stage remained nearly uniform or even
[n density under certain conditions. The sections with the
t hoasQs of lowest rental, aw Ward 8, appear to be increasing rapidly
I ^ite id fi density alrc/Mly very great. In fact, the greatest increase
> tliB whole cit>^ in the past 15 years baa taken place in those sections,
\ it ap|)earst to \m very hazardous to assume that the density' in such
' ' r : liigh, will not go on increasing. Where a

" , as between u piaffe for business and a place
ace, Its uftimate course may largely aJTect the density. If it
I ootnmercial the detinity may not change greatly or may decrease,
II

w

182 AMERTCAI^ SEWERAGE PRACTIC^^^^

I

1

:

\

\

;

/

V

f

rV

7

//

1

/

3

\

y

7

/

IV

/

1

1

y

;

\

\

/

/

J/1

n

ff^

/

I

/

§

:

\

^

/

/

/ 1'

i

?

;

\

^

/ li >

- b/

i

!

j

\

:

1

V

)/'■■

J

'

\

^

i

/

!

/

^5

.11 w \

4

T

■"1

I

\

1

;

W

\

T*^ BA

!

1

|I

\

•3

Sn

s

/

«

^

\

/

iV''

J

J

f

/I

1

X

V

/

J IV

MAil

n

[

y\

Wi

I

— ^2 J

J

V

jto^

^<

'y

/'r>

//

1

8

;

i

h

/

1 ,

lL

:

1

'

r

—

J^fisjjl''

\

—

3

h

;

<*

)

/

V

i

1

*o ko ^ m fu ^^ 2

V

; 1

V

']

- \

fliii

1

^4

\

I

\

\

0

\

1

11

Ji

A

\

\

)

n

iN

i

\

-

1

l\!

'

J

^Ai

h

1 Q

k-\

:

/I

!

/•

r\\

1

■T^

^

rr 1

\

i

y

V

\

1

-|\

>^

\

\

\

fl

■

\\a

^

\

i

.

m o (^ o kn
0^ o rw ^ ftj
** lU • * -

J

I into a cheap tenement region, the deSS^^ay go on
high figure.

tABi.E 42. — Growth in Population op tbe Wahds of the City of

Boston

I

W*fil

Am

iMldlfl

1895 1

)9(KJ

1W06

IdlO ]

■

Popul.

p«fr
acru

of
popul.

PopuL
per
Acra

Pcf

of

popul.

Popul,
p<?r

For
oeet.

of
popul-

4.27

Popul,
per
•ere

Pot

cent,

of

popul.

■

I

1,188

17.7

4.23

19.2

4.07

21 4

24.9

4~43

Ib^

357

60,5

4,34

64.2

4,09

72,6

4,35

80.7

4.30

n"'

332

42,0

2.81

43.9

2.60

44.7

2.49

46.2

2.29

i

301

44,4

2.69

44.0

2.36

41,5

2.10

44.1

1.98

5

207

62,7

2.61

62,0

2,29

61,7

2.12

61.9

1.91

6

293

05.1 6,01

104.3

5,45

102.3

6.04

122.0

5,33

7

394

43,0

3,42

37.5

2,64

39,5

2.62

37.9

2.22

n

171

135.0

4,65

168.6

5,14

180.4

6.17

190.0

4.84

9

im

124.5

4.66

132,0

4.38

118,9

3.72

141.5

3,94

10

394

57.2

4,54

56,2

3.95

60,5

4.00

64.3

3.78

n '^

6fl3

30,0

4.01

29.1

3.44

33,7

3.75

41,4

4.09

■ >^

235

92.0

4.35

100.6

4.21

92,5

3,65

103.4

3,62

■ 13

Oil

40.7

5,01

37,4

4 07

35,4

3.64

35.3

3,22

m 11

405

47,4

3.86

53.0

3.82

54.7

3.72

58 2

3.62

15

277

672

3.75

7L1

3,51

73.3

3,41

76.6

3,16

16

564

28.9

3,28

35.5

3.67

38,9

3,68

45,6

3.82

17

460

45 8

4,25

54.4

4.46

52.8

4,08

57 4

3.94

IS

220

98.6 4,36

101.9

3,99

100. 0

3,72

103.3

3.39

10

760

29 4' 4 50

35.7

4.85

38.4

4,91

41.7

4.73

90

1.710

12.6, 4. :i3

19.0

5.80

24,4

7,02

32,5

8,31

21

040

30.1

3.88

37.3

4.26

41.5

4.46

50.5

4,55

23

760

29 ?

4,49

33,7

4.57

36,6

4 66

38 1

4.47

33

7.617

2.4

3,68

3,1

4,21

3 5

4,44

4.0

4,57

24

3.252

5.6

3.67

8.3

4.83

9 7

5,32

11 6

5.63

M

25

2,740

6,6

3.02

7,0

3.44

8 0

3.66

9.7

3.96

20 0

22 7

24 J

27 1

Bimikr taodenciea in Chicago are Indicated in a report on sewage
^in the ClHeajio Sanit'iry DiHtrJct, by G. M WL«ner. The average
' ^ho four iuo8t iieiiaely populated warda mereai^ed frum 76.2 to
irs, Tahle 43. The Icnduucy for the density of businesa
'"'^ ^and «till or decrease aomewhat h shown in Fig. 55,
rcfiori. It i^hould be borne in mind, however, that this
Ti and that the number of people inhabiting
uKiness hour?* \b probably incroaaiug at a

164

AMERICAN SEWERAGE PRACVCB

Fig. 55. — IVrcentage of ciian^ in popul^uoa in the wmrds of Chio

■

QUANTITY OF SEWAOE 165 ^^B

w

B Table 43 -

"Population

OF Chicago by Wards

^H

Popu

lation

Per cent.
cbttDio

Denaity

^^^^^H

1

wwa

1900

WIO

1000

10 to

^^^^^M

1 1

1,440

43,764

29,528

- 33.0

30 4 20.5

■

800

44,683

42,801

- 4 0

55,0

53.5

^^^1

IB

960

44,425

46,135

4.0

46,3

48.1

^^^H

1^^^^^

960

49,058

49,650

i:o

51.1

51.7

^^H

^^I^K

2,240

48,206

57,131

19.0

21.5

26.6

^^H

^^^^^^

1,U00

57,831

75,121

30.0

36.1

47.0

^^^1

1

4 J 60

65,074

90.423

(W.O

13,2

21.7

^^^1

1

13,624

49,493

68,510

33,0

3.6

4.8

^^H

■

640

46,984

44.801

- 3.0

71,8

70,0

^^H

H

640

47,525

51,707

9.0

74.3

80. h:

^^^^

H

1,120

57,601

57,564

0.1

51.4

51,5

^^^^

H 13

3,SB0

60,246

91,521

S2 0

17.4

31.8

^^H

1

1,600

43,266

58,721

36.0

27.1

36.7

^^H

^M

1,280

49,299

52,770

7.0

38.5

41.2

^^^^

^M ^

1.120

49,178

60,438

23.0

43.9

63.9

^^^^

H

800,

58,158

65,223

12.0

72.8

81.6

^^H

1

720

66,084

70,099

6.0

91.9

97.4

^^H

■ 18

640

31,404

26,137

^17.0

49.1

40.8

^^^1

H

640

62,024

58.023

12 0

81.3

90.7

^^^^1

■ 20

800

49,271

61,708

35.0

61.6

77.1

^^H

B

960

50,283

47,906

- SO

52.4

49.9

^^H

H 33

960

52.523

49,324

- 6.0

54,7

51,4

^^^1

H 33

800

45,601

44,320

- 3,0

57.0

55.4

^^^1

I ^^

1,120

43,465

52,428

21.0

38.8

46.8

^^H

1 25

4,160

54,588

99.696

S3.0

13.1

24,0

' ^^H

^^^^H ^

4,640

43,354

74,793

72.0

9.3

16.1

^^^M

^^^H 27

20.480

44,290

113,336

166.0

2.1

B,5

^^^M

^^" 3ft

1,760

55,605

68,183

23.0

31.6

38.7

^^^H

1 ^

6,400

51,243

81,985

60,0

8.0

12.8

^^H

1 30

1,280

52,757

51,308

- 3.0

41.2

40.1

^^^H

^L 31

11,200

50,964

78,571

54.0

4.5

7.0

^^^^

H 32

8,480

40,211

70,408

75.0

4.7

8.3

^^H

B

33

12,944

37,100

70,841

91.0

2.9

5.5

^^H

^^V

34

3,200

20,611

67,769

155 0

8.3

21.2

^^^1

B

, 35

4,960

28,086

1,698,576

59.647

112.0

6.7
13.9

12.0

H

m

fCTr^

122,008

2,185,283

28.6

17.9

1

1,099,850

54.4

^^^^1

^^B, ''' I'^Ti'v

14,557

^^^H

■ P'luncin Park.

2,000

2,329

3,694

68,6

. - . . . ,

1 85

^^B

eisiuiAnd..

1.280

6,114

.S,<M3

31 6

6 28

^^^1

*lMt«U^^,t*"*

•Uff«««.

"

J

166

AMERICAN SEWERAGE FRACTWE

PKOFORTION OF MUNICIPAL WATER SUPPLY REACHING

SEWERS

It iH natural to think of *jewage as coaaisting of the water supply dcfild
by tiie wastes of the community, in which case the quantity of wnt
consumed would be an accurat-e meadure of the (ituintity of sewage pr
duced, ThiB impression, however, h incorrect, a^i otdy a portion of
municipal water supply reaches the aewers and this may constitut-c ^
than half of the aewage because water from other sources aJso goes h
the sewers,

A conBidcrtible part of the water supply used by railroads, by manufa
turing establislmicnts and power plants, in street and lawn sprinkling, 1
extinguishing fire*^, and by consumers not connected with the sewoB
fails to reach the sewers and there is usually considerable leakage fro
mains and service pipes. The Milwaukee Sewage Disposal Commissid
estimated in 1911 that the fjuantity of water Bupply for the several pur-
poses listed in Table 44, never reached the sewers. This \b a total of 40
gal., or 38 per cent,, of the supply at the time, which was 105 gal.
per capita daily.

Tablk 44. — Estimated Quantity of Water Supplied

Reaching the Seweks, in Milwaukef, 1911
(GftUona per Capita Daily)

Steam railroads

Manufacturing and mechanical purpos<^

Street aprinkling.

Lawn aprinkling. .

Consuinera not (lonneoted with aewers. ,
Leakage from maina and aervioes. .

AND

a
5
5
2\
7i
15*

io

Total .,;

* TIm leakage probably ercatly eiccedi this in many citiea.

TmMxm 45. — Pekoe NTAOK which the Fwjw or Sewage was of thk
SUMPTION OF Water in Various Cities DumKO Successive YEAna

Alttflfl, No «r . « IX
Met Sowerug. Wo™t*r, Broektan,

Di-trict ^**"^ 1 ^**-'

Qiuney,
Maw.

IIKK). . . .
1901.
1902.
1903

im^ .

1905

1906...
1907
1908. .
1909..
1910. .
1911 .

127

110

123
120
120

12'«

155

109

ir>8

173
112
124
162
166
163
164
140
145

59

151

66

m

60
56

130

ia5

117
120
123

113
143

156 J
153 j

144

150

73
66
69

63
65

130
Hi
120
12S

QUANTITY OF SEWAGE

1G7

* probably true that in many places sorae of the leakage from mains
Tvici'^ ultimately titid-^ it^ way into the sewerH by infiltration but it
fo to deterniino the jjroportion and it will vaiy ^n^ally in difFer-
I iiiitiea. In spite of the fact that all of the inuiiieipal water sui>-
fdoc$ not reach the sewers, it is important to know its quantity and to
5 th€ flata ill forming an estimate of the quantity of sewage whif h will
Jfirmluced, particularly during the dry .season of the year. Tliat the
wnii^r supply is a very important function of the flow of isewage is in-
dicated by Table 45. It will be seen that although the relation between
i two varies widely in different cities, the relation it a fairly constant
uc iij the same city from year to year.

Rjite of Consumption in Different Parts of a City. — The consumption
f wiiter^ and consequently the amount reaching the sewer, varies greatly
ent districts of a city. The total amount of water delivered in
I of the requirements for public, domestic and industrial uses and
Sldiount which is usually termed "waste," although "unaccounted for"
^ter might be a better terra- Water ased for manufacturing was
1 in 1904 in the Massachasetts Metropolitan Water District to vary
L?nt communities from almost nothing to 24.9 gal. per capita of
opulation. James H. Fuertes estimated the amount used for nianu-
^cturing t<j range from 0.4 gal. per capita in the residential town of Welles-
I to 81 gal in Harrisburg, as given in Table 4G, from his report to
h« Merchants' Association of New York on the futtu^ water supply
t city* It must be remembered that these figures are based on the
[)pulation of the city, and that if all the manufactiu'ing is concen-

TiJM«i; 46. — SmimvisioN of CoNstrMpriox into Various Uses

(Oiklloiu per Day per Capita),
iJmmvm II. Fuurtea. Report oa Wu*t^? of Wuier in Nrw York, 1906)

if^t

Convufxiora* unto

Not 1
for

Tat»|

OOIU.

Por
an-
for

8*r-
vicf?a

tertidp

lb'

Mfc.

Do-

niMiin

Tutiil

MktMl..

i9(H

5 1

15.5

20 6

3.0

13.3

36.9

36

91

mm

1892

30.0

30.0

mo

3.0

32,0

95.0

34

irrdanii .

190I

40.0

2fK0

66.0

10.0

20,0

96,0

21

49

Jl ItivcT

mm

23,4

8 3

8,7 40 5

21

95

vUunl .

1904

3.0

30.0

33.0

5.0

24,0 ' 62.0

39

99

ifrbburg.

\m\

81 0

30 0

in 0

6 0

30,0 146.0

21

75 ±

bWTttHOf*

1904

8 0

17.0

25.0

5.0

12 0

42 0

21>

87

lihrwkm.

1901

45.0

25.0

70.0

5.0

14.0

89.0

16

79

Udkon.

\'Uit

21 0

13.0

37.0

71.0

52

96

tnaam.

.59, 3

31.0

70.3

ISO;

20.0

108.3

19

72

K*

14 7

2K6

36 2

3.0

24.8

64.0

39

45

m

0.4

28.6

29.0

2.5

23.5

55.0

43

10(>

WkfTJ .

, I'JUl

n 0

30 0

51 5

2 0

40 5 94 0

43

too

A

168

AMERICAN SEWERAGE PRACTICE

Table 47. — Water Consumptiok per Capita ik Houses of Different
Classes, 1910 or 1011

(Journal of the New England Water Works Aasooiation, Maroh, 1013)

Cily

Aparlment
bouMA

FinV-dui
dwell] Of*

I

m 2,\M 37

B»ltlmare, ^Id.
Botttja, Ma«. .

BoetHtiji, Mh»i I ^ ..;.,,.. .

CiimbTidKe3IiiM.,.l m 1,242 37
Caoandftiffua, N. Y .| 50 SiS] 02
Df-'nuoiit TcE. > ^ . . . . .. J .......... .

FaLL Riv«?, Mau . . / J ^ . . .

Hftrtford, Conn..- .J Ifl,
Hartford, Cotia.. 75

Ho1yok«, Mum, ... / 20

Hol^Qke, Mutt 4T

Puirtuckei, It. I. ...... , ,,*... ► . . .

Pawtucket, H. I.. . . J

Pi7ori&, ILL .. . 5 150{ S4

Peoria, III ...J h 20o| 63

Plynjouth, Mnas. ^ .. L ,,..,*. , . . . .
WaaLiington, IK C. 101 ! 3.470|l3S
WiLmmstoDi, Dr»l..
Wori'L'Btor, ^IiLMJi.

500
1,247
2,215
2JIS

40 400

250
200
15S

S5»
740

I
3s

OQ

02 50

MiddlfHcLaJii
dweUinsi

I

I
It

Loiml-elaw

dwcUlngt

fiO
SO

200

m

12&
T50

300

lao

457

135 iaS6

ao: 112

( apart meniB witbstorH]
'L,. J 483 4,005

25 500 73
6(1 1.^75 m

I

30
104

04
500
ISO

501 277

20 80

25 . 125
15 67

100
25
50

400
125

385

TptalB 407 15.089 .... 727 4.115 , 1.302

AvrrartP*. , i\2 , . . . "54

54
3S

0JS8'

34

25

ISO

\m

60

50
600;

m

OS

SI

750

7,000

250

146

3,O&0

1.304

760 T.l«8

444 4,531

5 1£

8
2

100

40

I

500

60 KITS

2.258^ 23.01 «

I

u

ft

1 Lowo8t-cl(i8s dwellings, lower figures » those for tenement blocks containins from IStoSO
families each.

trated in one portion the per capita consumption figured on the basis
of the i)opuhition of that district would be very much higher. The
quantity used for manufacturing depends entirely on the character and
amount of the industries, and whenever possible an actual canvass
and estimate of quantities should be made.

The amount used for domestic purj)oses varies with the class of residence,
first-class residences with many fixtures using more per capita than th^
less elaborate houses, as shown in Table 47.

In some of the largest cities where considerable districts are almost en-^
tircly devoted to business and the number of people in the district during
the day, but resident elsewhere, is very large, i)er capita figures of oon^
sumption must be studied with great care before any conclusions ar^
drawn from them. The figures in Table 48 illustrate this clearly-
The subject wjvs investigated by the Metropolitan Sewerage Commission-
of New York which reported in 1910 that the actual resident population
of the Borough of Manhattan was increased about one-third daily by

QUANTITY OF SEWAGE

169

Taklk 48, — CoNBUMPTioy OF Wateb in Sections op Manhattan

^W. W. Bruiib, Proceeding* Am. Wat<if Works Aaaoc, 191 2>

"-

CunsumptioUf

11jMirl«nfc

Conaunipuon

ChAfftct«riffiics or diiiriot

miUioo z%X.
per day

nxmwasm
POPulttlion

per capiU^
gal. per djiy

(lugings of 1902^03

^Bp h(%t0\sk, hif^h-dfiss residences.

1.87

8,396

223

^^fc8iiJe tetiemoiits ,...,..,

1.44
6.40

38.906
90,000

37

60

^^iSide tencmitsnU .

WKmimaA luid high-class apart-

0.76

10pl04

75

ItlirtltiC

^Uiiiii*s8, ofH<ie buildings', wotrr-

9.45

11,000 1

860

ifimir shipping.

lJgh*cioas a^MLrinienU and hoteli^. .

1.37

8,872

154

Jptcfuti residences and niedium-

4.80

4,380

112

■^u» iipMrUi«cmt».

|Hbr East Sidi' tenements, water-

2.75

30,969

69

PYroiit, ponver houses and breweries

^^ (kHiinga, 1911

^h Hide tenements, some water-

IL44

230,500

50

29.48

204»567

144

^^^H^bw apartintiui^ ami rcdt*

22,18

186,990

118

BSfccTiww iipartmenta, reeidcnoee

12.74

138,800

92

1 and Ut}|i>nient8.

EMt Side tenementa and water-

8.28

84,580

98

1 (loot.

HHEfeM|i|NU^ f^gitlonced,

14.82

173,000

86

1 HBBBEHvfiriH ui\firrr^r<r

4)iaa»H«..

13.38

169,100

79

All flawwy* .

13 56

200,393

65

Tauli: 49.— Rksidk^t* akd Total FVjpulations of Cektain

DjKTKlCn* IX MAJ>fHATTAK, 1903 (HiLL)

Tout

Iac^rcft«e nf total

Dkiitf

popular

ovfTf resident \ ChftmetQr of dlotntrt

1

tim

poptilAiiou i

12.156

45 per omit. Residential and high -class hotel

2

38AMX>

0 i)cr writ J Tenement lioiiwea.

3

90,0tK)

0 per oeni ' KahI Side t4Miement«.

|(

S2,2m

32,450

1 pvT cent.l Moderate priced apart.ment5.

w%

10,161

10J64

0 per cent. Apartment houaoa; private
houses.

7

ai,076

6,076

98 per cent. Has works; large shops; rail-
rotwl yards.

K

11,(1)0

n4JK)0

937 per cent, 0!fi»»e buildings.

9

1

8,872

0 per cent Apartment houses; private
1 bouses.

170

AMERICAN SEWERAGE PRACTICE

the influx of persons engaged in business pursuits there but re^ddiog I
where. The various transportation conipaniei? bringing passeiigeTs int^
the borough flt^ni^hed infoniiation to the Coinnils^ion indicating th
413,500 re.sidentfl on Long Island, 203,800 in New Jersey, 17/200^
Staten Island and 42,900 north of the Bronx came to Manhattan (
for business piir|>oses. A somewhat earlier investigation waa m^
by Nicholas S, Hill, Jr., while Chief Eng. of the Department of WaU
Supp)ly, Gas and Electricity of Manhattan; the reisulti are suuimarii
in Table 49, from Eng. New9, April 9, ina'i.

This! influx of non-reaidenta, which is the cause of greatly increa
fl*)w in the sewers serving such districts, doubtless has a corresponiUn
though smaller, effect upon the flow in sewers serving the di^^tricU i
which these persona reside. However, as their residences are widd
scattered, it is probable that in no place will the reduction in flow I
suiJicient to warrant any allowance for it in design^ although it j
very important to provide for the increased flow in the sewers i
the business districts into which they go.

Water Consumption in Cities«^ — The consumption of water in Amerioi
cities, particulaily the different classes of consumption and the variatioi
in the hourly, daily, weekly and montMy rates at which water m i
is discussed in detail in a report by Metcalf, Gifford and Sullivan in t
Joumni of the New England Water Works Association, March, ItHl
ujjon which much of the following discussion of the subjcei has 1
based. From that source are taken the curves of the percentages
services metered and the per capita water consumption in Worcei
Fall River, and Lawrence, Mass., and Pro\^idenoe^ R. I., shown in
56, In spite of the large proportion of metered servicers, tlie quanti^
of water consumed is seen to have steadily increased in Fall Hiver uri
in 1910 it was about 50 gal per capita, a relatively small consumpti
however, A similar increase was apparent in Worcester between IJ^
and 1004, since \vhich time it has fallen to nearly GO gaL per ijapil
In Lawrence, with a steady increase in the proportion of sen* ices met(
there was a nearly uniform reduction in the qtiantity of wnt^jr used fr<
1892, when the consumption was slightly in excess of DO gal, to 1904, wli^
it fell nearly to 40 gaL per capita daily. From 1904 to 190!*, howc^"^
there was a shght upward tendency. In Providence, R. L, where \
water system has been generally supplied with meters for niany yei*
there has been a gradual tendency toward increasing the per
consumption although in recent years it has exceeded 70 gal. but on

The immediate effect of largely increasing the proporticm of met<
is shown by the Minneapolis and Cleveland curves. Fig. **j7» in wh
the drop in consumption following the increase in meters hi4s been va
substantial. *

In the cities in which but few of tlie services were metered* and 1

QUANTITY OF SEWAGE

171

r tfforte made to restrain waste, there has been a rather ^steady
in \yee capita con^mmpiion. The quantity of water u»ed in the
llich ftre not well supplied with meters is found, a.s a rule» to be
rexeessof that in the cities where metered services are general,

b dbnrn in Fig. 68, by the two. curves indicating the average

S

•20
110
100
90

no

'

""

— 1

1 1 1

^

^

^

^

^

jjj

i"^

sijt.''

'A

**

^

w^

p^

'

) ■ . , : .y

yWtff

Mosi.-

^

•^

^^

V

s

tn

_^

UJ

i_^

_

-J

TJIOO

«

2 60

~

^

^

^

^

^

^

^

^

^

iJ

s

z

$

0^

''

''^S

£11^

b-J

l—

^Cb//.

^.

/

h^

^

??Pf«^

, 1 TT

•'(-'

t ^

L L

J^

/

p»ll Ri...^.- iJI».. .

tid

r

_

1 — 1

t.^

1

L^^

40 5

Mi
20 "^

^C'^-'Wat^ eonsumption in Worcester, Fall River, Providence and

Lawrence.

lun ill cities having lass than 15 per cent, and the

iiption in the cities having more than 50 per cent.

1' acred,

...J thlTeninoe of opinion relative to the effect of meters in

^ quantity of water, sonic holding the view* that if meters

> tbtt water eonsumptioii will be [lemianently reduced^ while

riiMM

172

AMERICAN SEWERAGE PRACTWB

otiiera, ftcfaiowiedsbg timt the hnrnfyturfff Fesutt of mteffiog nuetera
wamy he m redaotiop iit quantity, believe thai iJtm tendesMSf of tho ^wom
h toward the lue ol grodoalljr iocreuiiig qmatities nod that the effect
of meifcefi io redocuis oonsampitioii will gnMlnadly be oSaet imiil the re-
dnettoa effected u wiped out and the oaostmiplaoQ grttdmllf increaaci
begroikd th^ of the time the meters were installed. All admits Wwever^
the tendenejr of metera to check the waste of water.
There is sonie foimdatioii for both riewsL It seeing CTident that a

Mismsipiilis, Sloatimtaiif

Fic 57. — Wmttr

Ihoromgh ^sleiii of mHennK will be aa effecthre indtniiiieai in the
baDds of eofiaCTentiou:9 and oafiable fiuuuic;enM>at; on the o^her hand, the
mof^ fact (hat meiefs are ivmided Is no fnaiauite uf a Um water oon-
emiiiioa, and if the mifieta thenMlvos $g^ mflecied aad allowed Io
fBOi^ oat fif refiair, iir tf the faula to tw kanifd from the reoord* cmi-
|ijlrHl fmm ikcmi am* rtiv*. u i^rli uttlkkiNl hx th^ nfllrhilr to chaiwfL thf!v nay
fi> l^osttbk hinetion m holdiiig down

^^^^F QUANTITY OF SEWAGE 173 ^^H

^V It U, of course, desirable that the municipality should provide all the ^^^^|
wmkr which its citizens can me to advantage, but there is nothing to be ^^^^|
waJid in hvor of the waste of water throuyji neglect of fixtures, faulty ^^^^|
^ jaipc hnc^ and ser\4ccfl, or surreptitious connections through which large ^^^^|
^^^Hptiliii!! fire too frequently drawn without payment therefor or even ^^^^|
^^^^hupScdge of the proper officials. Such consimiption not only ^^^^|
^^^^^^■he burden u|>on those who pay for providing the water works, ^^M
^^^B*^ ' increase the cost of aewerage, particularly where pumping
^^^B 1 Ki are necessary.

r loir watisr rates tend toward the use of increased quantities of water
^H AOfl may render the meter less effective as an ageut in restricting waste,
^■iQ ihat the size of the bills due to waste may not be suifioiently large to
^■(Bftttse an t^ffort on the part of the consumer to economize in the quan-
^L^^ of w.iter drawn through his fixtures. These observation!* are ^^^m

J f 1 T -1 1 1 1 1

A\^raqfoff4 Cities
Having fesi than fS%
, Services Metertd,

»70

^^H o ma

/

"■

/

^

f

^

>

/

^H X

^ • ■ -

t60

70

^H

th small iind ^^^^H

quantity ^^^H

» warranted: ^^^^|

(quantity ^^^^|

due, so far ^^^^|

The number ^^^H

i per fixture, ^^^H

he increased ^^^H

[>undittg the ^_^H

luch greater ^^^H

furnished by ^^^H

indicates ^^^^H

metering, it ^^^H

Mri/i

nq mom than 50% -

V,

1^

^

■««

r*

N,

Sw

^

^^P^. ^.— ComfKKslte CI
^B largt

^^H% pertinent to i
^■Satrr at {& low minin
^^^Prum the grtatisticsi
^B^fvt, there b A griu
^Kf wiier used ;

^W iitura per ijerson, i

™^kw|frcitly IncrroHed i

^'miiilptiofi mnv Imj

Hib|ktL. ,,.. i oit

^^^MUi lanf ul mani

? g S 2 if

? 5» ? 2 S

ntxeB of water consumption in citiea wi
; percentages of scrviccji metercil.

■ules permitting the use of a large

num rate.

available two conclusions seem to be

ual tendency tow*ard incrciise in t

of population. This is undoubtedl.

uses, to more elaborate plumbing*

IS well as the quantity of water require^

ri recent years. In the larger csities, t

due in part to the dilTiculties surr
iter departments, which are usually n
iea and towuj*. Second, the evidence
<Mi, W<*rocstcr, Fall River and Lawren
i^oment aided, perhaps^ by thorough

^^V 174 AMERICAN SEWEHAGE PRACTICE ^H

^V J i i i 1 il

" t "

M n 1 M

ik^

Cincinati, Ohio*

tfSI

?/

\

'

k

d

ISi

f/

\

J

A^.

A

/

— lAi

<=»

/

VS

jlV

r

TV

V

7

\

/■

/

1

<

&-

A

']

r<5

I

ISI

s?

^\

-<

Wr^y!

«

/^fj-

V

iq'^

T'fSrCJrtf

J4^^-

\

l4U

f 1 1.

n^^?ef

-

/N^ .J

1/

^

tai

or^

^^

\

7iU

n^\

ft

^4^

t\

tfll

J

\

i^

■J

V

s.

'I*

/

?

■>

!

/

I

L

h-i

?ffi

/

V

y

?'

Si

£S

\

'S

\

1 7lj

}

V

/

\

cu

>

f

Plttiborg

, Pa.

\

-»A

1

\

lAi

^ "^

■ ^

r

^

V

a

is7

>

^

L

7

-I «l

■?/

\

/

\

OS

.

»V

T

P —

\

1M

^I

\

/

i

^

J

y

T

\

'n

1 J

4

i

y

CI

<5S

^-P»rC€

nt ^ Jervkei

—

—

— If

F^

M€f€rm€t^

k

,^/^?'

^J

f

-k

If

Philadolphia, Pa. i

>

3^

/

J

f

'

^^^^^^^^^^^^^H
^^^^^^^^^^^^^H
^^^^^^^^^^^B

\ i i

1 1 1 l|

Philadelphia, I

^^^^^V QVANTITY OF SEWAGE ^^H

m {xmlile to hold ilovru tho increase in quantity of water consumed ^^^H

to neiisonAblc proportions. Tins is abo well illustrated by the recent ^^^H

n4uction 111 conaumption in Pittsburg^ Cincinnati and Philadelphia, ^^^H

II ^y^A-n m Fig. 59. ^^^H

H Tho Milwaukee Sewage Disposal Commission, which studied tliia ^^^H

^qiloliun ttiircfully, imd in 1010 that, taking into account the history of ^^^H

tlie Milwaukee u*ator workr^» the indastrial character of the city, the ^^^|

luw w »f 6 rentrt per 1000 gal, as well iw the availability of river ^^^H

n *^ '- *t wiks of the opinion that an increase of 5 gal per capita ^^^H

^■p**^ decade was a reasonul)U! alluwance to make for the next 40 years. ^^^H

^B Floctimtions in Water Consumption. — While it ia important to know ^^^H

^Khe average quantity of water con.^um[>tion, it ia of still greater value to ^^^H

J

s

^

\

. A.r ^^^^^^H

^^^^fe

J

/

\

A

\

,**m. ^^^^^^H

^^^^H

/

\

1 1 e ^^^^^^H

j

\

. ., A ^^^^^^H

/

\

■ , 100 -

-1

/

L

_

\-

H 9

~

^

T

~

7t

tr

^9

m iH

^B

r

r

\

/

1

s

^H

■ « 80-

f

\

\

^^^^^L

^^^^^^^1'

^^^^^H

^^^^^^H

^^H

'S

.**

H

•

- es ^^^1

^^^^^H
^^^^^^^B

^^H ^1 E 5 4 5 6 7 fi 9 10 IMl 1 Z 3 4 5 6 7 B 9 lOU 12 *^ ^^^H
^^^V ic„- -5J<'— - — ' H ^^^H

^^^H Hours of Day. ^^^^H

^P"*' ^.— liouily water consumption fur average day in llalyokc in Nov- ^^^^|
^^ ember, 1905. ^^H
^^^K Entinifttpd populfttioi} supplied, 5t.fK»h ^^^^|

^^^B ing to the fluctuations, as a »ewer must be designed to ^^^H
^^^B ^n whcm ilowtng at its maximum rate. The maximum ^^^H
^^^M waier consumption usually occurs during summer months when ^^^H
^^^V>>b dpjnatid for jfireet and lawn sprinkling and the excess is not ^^^H
^^^BMj> rwiu^h the ricwers^ or in the winter when large (luantitien are ^^^H
^^^Blk r vent free/.ing of pipe^ and fixtures, this excess usually ^^^H
H^^P^R' .:'.'} the aewers. In Table 50 have been compiled ^^^H
irnum water consumption for 07 Massachusetts cities and ^^^H
I^^H nm from report of Conimittoo on Water Consumption, ^^^H

^^B 176 AMERfCAI^ SEWERAGE FR ACTIVE

F

^^^^^^ Table 5a— Rscosmi or M AxniTrif

Water CosrsciiFTiox

mm M^

^^^^^^K cttCBBTm CrnEa axi> Towns, 1910

^^^^^^r

fBy ecMtrt«*y til X

H G<>odAcra<h)

^

\l\% mr>n%^\y Mai- wcvUjr

M«w ^i

^^^^^^B

, Avcn^Ce

rootfuiupUoo ^onsamptJoii

tsvumLmi

^H

City or lowB

'"ss-

dAily

ittfllfK

per

Per 1 «_, i Pet
c*n4. „ ' «^
of av* *^' , ol *T-

^^^^^^^H

tlooper

persuQ.

«"«* ''t!!!!^ "»•*

p^^. «

^^H^

pcnoo

5S

y«r ^^ 1 ye«^

1 Si ; ,

^^^^^^^^H

itivl RoefclMd.. IS.3S3 kh

03

137

70

ISl

»o

^^^^^B

l>*Mi4

41

50

114

51

ll«

o«t

^^^^H

7:Sl
10.215

80
54

99
02

US
1 115

l«2

;\LtlcLsjftitl«ll

03"

'iio'

^^^^^^^r

Avon

2.013

30

56 153

72

300

loa 1

^^^^^^^B

Ay»r,

2,7»7

50

04 im

72

144

172

^^^H

Hfffcrty ,.,,*..-,,..

tS.05O; 01
M.O00, 81

140
87

100

107

191

210
115

234
108

Bnklmfre ,^I.,

^^^^^^^1^

BrUffr«ftl«r sad E.

11,051 22

37

123

39

133

39

^^^^^^^■.

Bri(tff«r«r«t#^.

'i

^H

nrot^kton .

50.J*78 39
27.7\l2j 89
104.039 100

45

103

too

100

55
117
111

141

133
111

09 1
138
119

iffw^ldioe,

^^^H

•^pC^

4,797 01
lO.Sao 80

75 1 12.1

84
130

138
153

97
158

I08

121

^^^^^^^1

Wl

9,284 129

153

119

103

128

183

^^^^^^^1

&.139 24

28

117

38

158

03

^^^^^^^B

btt 1 7.1"!"!^

119,296 U

47

107

60

114

64

^^^m

^oxt>uruU£ti. ...(•••iij .'

12.9481 48
5.041 01

51
58
88

102
121
144

59
05
90

118
137
158

75
80
127

^^^^^^L^^

'rmuKun

^^^^^^^^^^H

rUr.sr H.IMW 44

49

111

55

136

IOS

^^^^^^^^^^H

rjt.M ,., 24.39» 5ft

90

iS

111

307 1

l»

^^^^^^^^^^f

rjr.i 5,7«5 18

23

24

133

n

^^^^^^^^^^^

Hu.r .. .! 5.743 49

00

123

05

1^

^^^^^^^r

Ip-TM .. 5,777 1 43

00

143

a4

300

lOft

^^^^^^^^

t*A,'w r. 1 ■ "

SJ5.892 45

51

113

00

US

00

^^^^^^H

L«mfll

h>Kl\^\ 51 1

57

113

00

m

7a

^^^^^^^H'

Lynn -tntl 8»0|tuii. .
\l/ini hiwtcr . .

-V iH3 72

79

no

87

121

108

^^^^^^^H

'•,7:i 120

201

217

327

271

soa

^^^^^^^H

MiiiielM'hf

5.1S3 75

97

129

103

137

370

^^^^^^^H

M.ifhW'|jr»fl

7.338; 79

147

180

100

214

187

^^^^^^^p

\tA^rtt)iiruu({ch

U,fi79 37 ,

42

lit

59

159

80

Mttviwird-

0,390 30

39

108

47

130

00

M*»«fnj<'n. .

11.448' 38

54

143

07

170

eo

\T[lI.nrlM.rr.,]».'Il

S,2H' 42

53

130

05

155

•0

15,2431 51

00

118

«04

125

7« ,

8,014 m

75

114

70

100

153 1

2.9021 07

128

191

154

230

170 ,

0.800^ 57

70

123

83

144

170

5.020 00

88

133

98

148

119

90.fV52 81

88

109

98

121

100

\k-v> iiiijr viiurt

14,9491 08

83

122

94

138

131

N'fwtoii

:J9,80« 03

7i 1

118

82

130

95

North An.li^vr

5,529 1 40

S3 1

132

m

lOO

W

Non '

9«502 52

73

140

82

158

0&

NN.i:

3.0751 00

81

123

112

170

'i

Nor

8,014

03

80

130

80

130

Orrk:

5»282

20

34

131

41

IS2

J*ruS

15.721

iOS

198

118

182

27C

nvp -■

12^41

103

131

127

140

130

IT*^

Pf'jv hpL'tOH'n

4,30fl

38

09

182

77

203

<>•:

R;inilutph and Holbrook..

7 J 17

74

120

162

J40

189

t-r

llnr^rUnje ,..,...,.... .

5.918

35

62

m

r>n

172

UfMikpon

4.211

72

148

2\ ■ ■

^ ■ -

?*«lem . ,

43.097

90

101

1

J

■ibjif 'Jti .

2.310

57

97

i.

Sto: 0,310

3ft

43

12J

a-S

*

Tm'

34.259

03

70

til

74

W„v

n,«tH' 01

85

139

107

■^

Wnii :

1 N^»2! 102

119

117

149

—a

Wnlf. .-.^

;t,s;H| 88

95

108

OR

X

W,-: ■■ ■

Jl,'.<>0'' 38

40

129

53

1 •''

.A\.-\ in

08

111

79

i<

^•9

«2

145

44

in

.ir»

117

40

too

1 ■•■

r.t7

1^4

M \2^ M U7

i

QUANTITY OF SEWAGE

177

I ^Htdtwtr* And Rccorcb, published in New England Water Works Journal
f'lrMifi-h, l!H3. Tht? average water consumption in I he cities and towns
I ihckiki in ihiH conipilatiou was 63 gaL per capita per day. The average
jtoixhnum monthly consumption, the maximum weekly consumption
\ml'^ ! iiuni daily coniiuniption were 128, 147 and 198 per cent.

laftj> flaily consumption for the year, respectively. There

jhowf!ver^ instances iti whioh the maximum rates greatly exceeded
Averaxei. For example, in Manchester and Mansfield, Mass,,
rtbiiiiiiiiimni daily consumption was 302 and 3G8 per cent, of the average
'tively. These hip;h rates of flow, however, ahnost
iiHi8 when the usual projjortiou of the flow does not
I tlie J«cwer!S, ^ in the most dry portion of the summer, or in winter

• H»ftday tf* Tu«doy-»|»We<4nesday^*ifr'Thunclaf Y* fi'nioy-'^Y' S*'^"**^"T"^^'^**y~"

,a 1 . 1 1 rrnrrrnrfyitri ii i n ii i

K H. M M, M. K H.

5' — '''^'(^•fimtioiiJi in water cfmsumptitin in Holyoke during week
ending N'oveirihrr 17, 1905.

vater from other sourcos. a-^ for e\aniDle, ttround water, L* likely
[be »t II mtotnnmi.

' 'Tffin to the flui'iiiiuuniN m iinw itiri'auv oisrussed, tlicre is an

v^ariatinti from hfnjr to hour c*uch day, a.s illustrated by Figs*

•m the siinir rej^Kirt. (A'* E. \V. W. Jour,^ March,

-»^n from Fig. til that the maximum peak flow during

: occiirrmi on Monday, when the draft was about 135 per cent, of

T. fur the day, and t!je minimum peak draft was on Sunday when

I IttV par cent, of tlic avnrage for thr day, thenc rate^ lieing 139 jier

r iod i;}2 per cent, respectively, of the average rate of draft for tho

178

AMiSHiCAN SEWERAGE PRACTICE

Table 61 — Relation of Assukl Avcraoe Quantitt or 8r.WA(S

TO Watkr Consumption. North Metropolitan Seweb Di«tbic7t.
Boston, MAt4».

Year

1904..
1U05.

lt»07.

HIOK.

IWHI

lUlO

U>11

1912.

Pwwipittt-

tion in
mchc*P at
Chftdtnut

Ba«4*fl on totjil populzitioo of
dUtriet

I syaiciii

43.40

40.84
47.16
51.83
4:1, 31
47.62
39.05
41.28
39.90

Avsmse
sowtige
flow, gal-
lotiH per
capita
per dny_

121,6

113.5
118.4
128.2
116.8
115,9
110.3
96.9
100,2

AvDrage
wator con-
sumption.
galloQfl per
capita

per day

Ratio of

SCWASQ

flow to
wat^r con-
•umption,
per cent.

100.3

121.2

101.9

111.3

99,8

118.7

106.1

120 S

104/9

HI 3

94.7

122,4

92.3

119.4

86.9

urs

86,8

115.4

Average 43.83 113.5 07 1 I 116.9 135.3 | ViSi M

Avermce

sewftge
flow, K»]-
lon« per
capita
per day

155.7
139.3
149.8

151.7
137 8
133.9
12G.8
110.0
112.5

Rfttic^ol

How Ui

Wtti.' ■■

jHtl

l&O.f
142 1>
131 Jt
141 4
137 4

129 7

U

Flo. 62. — Flow of sewage and water nonstjmption in North Mptitipolilj

8t'w«ir District, Busluti,

mk

QUANTITY OF SEWAGE

179

hourly fluctuatioa in rate of water consumption has a decided

IfSo-t upon the rate of sewage flow, as discu-ssed later in this chapter.

It ua not, however, eiitiiely rej^ponsible for the fluctuation in the rate of

of ^wagc, for in some places large quantities of ground water are

iped by industrial establishments and discharged into the sowers

iuritig tlie working hours of the day, thus tending to increase the peak

Iflow !w!yond the amount resulting from the normal fluctuation in the draft

|€B the municipal water supply.

Ttikias into account the fact that all the water supply does not reach

and in the absence of more authoritative information, 150

[per OQiit. of the average daily water consumption may be considered a fair

fWtliTiate of the rate of water consumption from aU sources at tiie time

when Uie flow of sewage is at its maximum. This rate, however, will

tnry in different }>lacea and estimates used in design should be based, if

ujKxn data obtained locaUy.

maximum peak draft is applied to the maximum draft for a
ihgteday (see Table 50) of 19^ per cent, of the avt-rage annual coniium|>
tiott, VKJ ft 13 AgKumed that the portion of the aiumal consumption which
fiad* its way into the sewers is 50 gal. per day, we have a maximum rate of
ft'' from the water supply of 150 gal. per capita daily of (50 X

I."' ' - 148.5). This mil ser\^e to illustrate the theory of the

yield of sewage hti»ed on water consimiption, but should not be applied
iod»«ign unless local conditions are found to warrant it,

Kitb of Sewage Flow to Water Consumption. — The North ^letro
poiitnn sewerage system of Boston furnishes valuable information re-
fwtling the relations between the quantity of sewage reaching a large
intereepter^ and the population, area, water consumption and rainfall of
^digtrict aerved* The relations between the quantity of sewage and
*iitwaii.ir consumption are given in Table 51, and the relations of tlie
IttttJmuin lo the average monthly sewftge flow and to the average monthly
•■tcr oonsuinption are given in Fig* 62. The circles representing ratejj
^ flow on days of maximum flow mu^ not be misinterpreted, for
w newer w protected by storm outlets, which permit the discharge of
•"luch of the flow, unmeasured, at such times, ^ The relations between t he
•«wajteflow and the water consumption for the dry period of e^ch year from
^'■^M til i*J!2 arc given in Table 52. The dry months were selected in
"»<s driest ^a*«on of the year and after a month of dry weather; in a few
*^^ they hIiow a rather high rainfall, but it was concentrated in a few

ThfiK\ avrifcu* BJinual figum are open to the criticism thai they include iiorn** ■torm

''',j '

of ihn UiCiii ftnwei^ divchiU'vLUK itito the tnlercepteni iktu uu tlio oMJiibilKHj

th*'l*>H*«, the figures Mfc f Airly rn»f''**'nttttivc of the wswiM^n flow lui lu-

< ici. Am ihown Hivr^ H la L^tiiimUHl t)iAt duHfif dry w^iithc*r, ff no

hn mw»rm, thn wtiwjmco flow wU\ hi* about iH intt ccut. of lJi« wntcf

' ' (n yitLi f^2 repr*mr>ntlns ihr HiwnhnrgQ on dnya of tujiximum

uum volufijc of ■owdiic) tind Atorm wAtcr. for the ovcrflowi mtky

ilHlMii

180

AMERICAN SEWERAGE PRACTICE

days BO as to leave the month a dty one as a whole. It will be m
that tlicre are no figii/ea for 1911; none of the monihly record '
year is representative of dry weather conditions. In fact the
1909 figures are probably high on account of some Tain-water in tli*
sewajje, the rainfall figures in the table making this appear vcrr
probable.

Table 52, — Ratio of Sewage Flow to Wateb Consumption pumxa

Dry Weather, North Metropolitajj Sewer Disthict,

Boston, Mass,

Year

Month

RAiufall (inohe-t)

AvtTiiKC

flow, go)'
lona per
cspiU
per a»y

Average
wfitcr ci-40-
sumpiLon,

I>er

Uiiivti.ua
flow Ifl

For

month

For

month

previout

1901

August... .

2,74

1.48

93.8

97. <i

y^ u

1905

August,, .

3,47

1.92

94.0

98.3

95.6

1906

September..

2.92

1.82

95.2

101,6

03.S

1907

August

1.70

1,49

88.7

110,2

60 G ;

190S

October

4,34

1.22

93.3

05.9

97.2

1909

August... . .

4.11

1.10

98,8

97,5

101.2

1910

Augti»t.., , ,

1.18

1.93

86.9

MA

92.1

1910

September.,

2.65

1.18

86.3

88,7

97.2

1912

September.,

1.72

2.24

80,0

83.4

95 9

1912
Avcr.apo,,

Oetober. . .

1.61

1.72

76-9

81.1

94.9

2.65

1 61

89.4

94 9

94,4

The average relation of dry weather sewajce to water cousumpti
is given in Table 52 lis 94.4 per cent. Thia would probably be rtnluw
by al>out 3 per cent, if it were possible to exclude storm water entirely
from the sewage flow* The eorrect ion of 3 per cent, way obtained fro
the graphical jitudy by the authors of detailed record sheets of th
Metropolitan Se%verage Board for seven tj^^ical months during IC*
to 1000 inclusive. From a study of the diagrams of sewage flow durlft
each rnocilh, it seeniB probable that the true ratio of !*ewage flow to wat<;^
consumption is about 90 per cent,, if the entire amount of storm wftt<
13 excluded. If this estimate is in error, it is probably too high, m
quantity of ground water assumed in rouncUng off the figures is i
almut r2tX) gal. per mile of sew^or, thin being in extremely dr\
This ratio, it must be kept in mind, i.s a purely locid one and k\.
be expected to agree with other conditions than those on which it is I
Unfortunately very little information of this nature is aval b.' *
engineers having opportunities to keep isuch records should li
to do so.

The ratio of 90 per cent, does not mean literally that 90 pi^ rent (

QUANnrr of i^ewage

181

r supply is delivered to the acwer, but rat hot that the dry- weather
f of Mswttgjb beiin* Uiat relation to the supply.

P

ADDITIONS TO THE SEWAGE

\Tlii\ii Limount of iiewagc reaciies the sewers from tha^e hotels,
public bjithd ariil other buildings which ^^uppleinent the public water
*ply with water from weUs, In addition to thia uncertain influence
the Mowage flow of a metropohtau district, there are t^'o much more
important sources of additions to the sewage, viz.^ ground water and
miluHtrial wastes originating from the use of water derived from private
twurcex,

Ground Water, — For sewerage purposes, ground water h a term
which iDdu<lcH not only all water in the pores of the material^] through
which sewers are laid* but also the surface wat«r leaking into aewera
^^^1 ' I'd manhole covers and defective manhole masonr>%

^^ - ai'e on the combined plan, ground v^ater also include/^

the dr)'*wcather flow of any small brooks comiect^d with the system.
Fmm a lialf to three-fourths of the rainfall u^sually runs off very quickly
"ito tiifi Ktorro-wttter drains or combined sewers, when there are any,
^'' under percolates into the ground, becoming ground water.

T^' >a of water from rivers, lakes, and tidal waters through

tbit ground sometimes has considerable effect on the height of tlie
IC'^ouiid'Water table. In such loctilitics, allowances should be made
'or If^kage into feewers, and it is desirable to construct tlie sewers
*hen ihe lakes or rivers are low and a I, low water between tides to
•Voir! expense and trouble due to very wet trenches.

The elevation of the ground- water table rises and fall"* continually,

*'*"' " tisi were formerly held by a large number of sanitarians

•^ f t^'phoid fever. Thi^ was known as the von Petten-

*^cT thwiry and U no longer held to be true, except by a vcr\' few persons.

'*'JWrver» the presence of large amounts of ground water in the earth

[I the neweru results in leakage into them, wliich causes a serious

'^^^^lem where tl f^ of disposing of the sewage is heavy. It is

* wine policy for ti ir'cr to neglect no opportunity to acquire infor-

'timtii^u rrfpiniing the phenomena present/cd by the flow* of imderground

The aewcn first built in a district usually follow in a general way the

water courses^ and therefore he in the bottom>i of the valleys.

iwerw are ofU^n, i»sf>etnally in cas<* of combined sy^items, built

do»e io, or actually in, the natural beds of brooks. They are not

-* - ^ i t<j the extrcMne upper end of tlie district at first, and

natural nm-off thiough tlicsc brooks is taken into tho

duch brooks freciucntly flow with gradually dimiuisliing volmno

182

AMERICAN SEWERAGE PRACTICE

for many days after the inimediate run-off from a »torm has passed by
and perhaps even tbroughout the dry aeaaoa. The fiow during the
mainder of the time until the next storm is made up of the water drainini
out of the land, and Ls therefore logically clasi^ed with ground water and,
as its flow 19 continuous though gradually dimtnijshing^ it has the s^ame
effect upon the quantity of sewage. Aa a result of these conditions,
such sewera receive comparatively large quantities of ground water, while
it is but natural to expect that sewers built in these districts in lat*
years, necessarily at higher elevations, wiU receive smaller quantities
leakage and brook flow, Moreover, as the paved and built-over area
creases the water falling upon the surface rims off more rapidly tliroui
the water courses, drains, or combined sewers, and leaves less to percolal
gradually through the ground and thus to fmd its way into the aew"
b}^ infiltration or leakage.

Many mefvsurenicnts have been made to deterrnme the quantity
ground water which finds its way into sewers. The results of these ol
vations indicate that the maximum quantit>^ of infiltration may be as !
under the most favorable conditionsj as 5CMX> or 10,000 gal, per day
mile of j^wer. On the other hand, they show that the leakage sometinn
amounts to from 20,000 to 40,(X)0 gal. per day per mile of sewer, and at
times of ver>^ high ground water, or during rain when there is le^ki
through manhole covers, even in 8e[>arat© systems, it may run as
as 100,000 gal per day per mile of sewor. In fact there are instani
where leakage has materially exceeded this quantity.

As a rule, there has been a growing tendency toward securing as nearl
water tight construction as possible, and it ma}' be true that the older sy
tems receive grc^iter quantities of ground water than some of the bet
constructed modern sj'stems.

Leakage. — The amount of ground water which Ends its way into
sewers is calle4 **leak^?e." It is a very variable part of the flow in
sewers^ depending on the quaUty of the materials and workmanship ei
ployed in the original construction, on the degree of care in maintonan*
and in preventing damage to the sewers by drain layers or pluml:>ei
when (connecting house cb'ains, and on the height of the grouinl-vvMi
table.

In the case of the North Metropolitan (Boston) intercepter, alr<
tioned several times in this chapter, it is possible to form a f n
estimate of the amount of this leakage, for if 90 per cent, of the average
monthly water coiLsumption is equivalent to the sewage flow at the
time, by subtracting this quantity from the meaiiured sewage flow,
remainder will be the infiltration into tlie servers. An ' '
great^t m very wet weather, the fi«:iirn^ fr)r tfie moM
yoar have to be iJtuiiiod^ and Uic r*- l study m thia

QUANTITY OF SEWAGE

183

ITablk 53, — ^Leakage is North Metropolitan Sewee District,
Boston, m April and May

1 Average \ Maximum | M minium 1

Cidlona per capitii per day G2,2

93,8
2,577
78,900

3S.7
1,094
30.900

CMloM per acre per day 1,738

[ttalloTW per rmlc of sewer p<*r day — 50,600

I The amount of leakage h stated in different ways by different engineers

^tnucli per unit length of pipe, per capita or per acre. It depends, of

y on the length of pij>e, and to a certain extent on the population,

U the ntimber of connections and the lengths of the sewers

[|8equent opportunity for leaks. In Table 54 are shown the

noes made for leakage in the designs for various cities and in Tal>le

I actual measurements of leakage at certain places.

A p^Hir on the ** Infiltration of Ground Water into iSewers'' by John

aks (Trans. Am, Sac. C, E., vol. Ixxvi, I90Q) enumerates the

influencing tnliltration, as follows: 1. The diameter and length

f the dower; 2. the material of which the sewer \s constructed, and (a)

jjij>e siewor^, tiie tyj>e of joint used, (h) in ooncret^e or brick

>t>*i)e and quantitj' of waterproofing used; 3. tlie nkill and care

wed k laying the ftower; 4, the character of the materiais traven*ed by

f BWrer; 5. the relative positions of the sewer and the groimd-water

^i After disc asking the various unites, such as gallons per day per

if^r per mile of pipe, he suggests the following units: For vitrified

fgallom* i>er day per foot of joints; for concrete and brick aewcrs,

gJi'lon* per day per scpiare yard of interior smface.

the discusaion of the paper, John H. Gregor>* sugge^stcd as a unit
nmiiher of gallons per day per inch of diameter per mile of eewer.
•1 stated that obscrwitions practically checked previous
to the quantity of ground water to be proN'idcd for at
^fw Orleans where all of the sewers are below the ground water level.
JMAtcd that the leakage in gallons per day per mile of viewers was as
Oub: UM17, 55,(Km; U»OS, 5:^,000; 1909, 51,000; 1010, 51,000 1911,
1912, 42,000. E* G. Bradbury questioned the value of a unit
Bfl on tiio diiuneter of the sewer, as but vorj^ few sewers are sufiiciently
ifti^ht to prevent the lowering of the ground-water in the viQinit>^ to
*■ level of the pipe, lie wtv* of the opinion that most sewers permit
J»*f catnmco of ground water alxmt as iixst as it gets to them.

In RWieriU Uie authors have found that water finds ita way into sewers

tln.iiiif. lU^- i ^Tve joints in pipes or brick structure-s, tlu*ough concrete

i and tlirouiz Ji erack^i due to oontraotion or other causes.

*•' ous and large to allow the in-

0*-"" Uie water table at the sewer

^boro ita crown and usually is found near the invert* although

184

AMERICAN SEWERAGE PRACTICE

<

P

2 I

:§i

eg

O OO 0«OiO
CO «« JMCO

00 00 w

ao*o* dbo'soo o

OO ^^tO C4

dOO^O ooo o

^-^ CSX N

gg 82 i!

OO 0?3 cc

o*« r>.'« e?

o -^ o ^ cc c

■CO 1-1 oi © c

MM . M

es 2 . tf

S6 :£«

Nooh. loor^^

■*«^«fl .coo

gS8 :g|S

5s
3

■SMO

-6

SB
-6

gi

.r»^^oo f^eo»c

cooooc

O O »0 «-• ^ C

oooo^-^c

WOOOf If

sii

o CO coo

0-. '-co
5JC coo

<nt t-c

ce

. ^- t. -

T^y*

csecr'.Q
fifCMO

3C--XO

p«co

SOW

o«o

! &

•S|c

i

s

J?.

J; C^ 3 O 3 #S 2 5 2

QUANTITY OF SEWAGE 185

Table 54 was prepared from the following sources:
Chicago. — From Report of Chicago Comn., 1897.

BnfUm. — Main Drainage Works of Boston and its Metrop. Sewerage
t>Utrict (p. 8), published under authority of Metropolitan Sewerage Comm'rs.
U899).

Man., North Metrop. Intercepter . — Report of Mass. State Bd. of Health,
^^rainage of Mystic and Charles River Valleys (1890).
Mom., Charles River Valley Interceptor, — Idem.

AfflM., Neponset River Valley Intercepter, — Report Metrop. Sewerage
Conun'rs. (1895) p. 38.

AfoM. Metrop. High Level Sewer, — Report Metrop. Sewerage Comm*rs.
High Level Gravity Sewer (1/1899), p. 44.
Bo/b'more. — Baltimore Sewerage Comn. (1906), p. 23.
Providence. — Furnished by City Engineer.

Paterson. — Report, Joint Comn. on Sewage Disposal (1908), p. HI.
^aui«'i/;«.— Furnished by H. P. Eddy.
^filwaukee, 1889. — Report of Comn. of Engineers.

Passaic Valley Sewer Project. — Report Passaic Valley Sewerage Comm'rs.
^1908), p. 7.
'^tilwaukee f 1910). — Report of Comn. of Engineers.
^np Bedford.— RepoTt of Metcalf and Eddy, 1911.
^tte^6ur^.— Report of Metcalf and Eddy, 1911.
%aci«c.— From Eng. News (July 13, 1911, p. 38).
f<^r( Wayne, /n<i.— Report of Metcalf and Eddy, 1911.

Main drainage fiffures are with sewers 1/2 full. The slope and sisc of the outlet section
"'*«^5epter indicates a capacity, flowing full, of 407 gal. per capita.
'^^ ^aterson report for explanation of figures.

Art** taken from census report and may vary somewhat from actual areas used in design.
' ^naity,
^ >n district tribuUry to 12th and 22nd St. sewers.
^O in district tributary to 35th St. sewers.
GO iti district tributary to 41st and 45th St. sewers.
Storm Water;

^ ^3 in. per hr., area north of 39th St.
^ - 25 in. per hr., area trib. to 41st and 45th St. sewers.
^ • -^2 in. per hr., area trib. to 51st St. sewer.
" ■ lO in. per hr., area trib. to 56th St. sewer.
^^rm Water,
^ 273 in. per hr. 12th and 22nd St. sewer.
^•l& in. per hr. 36th St. sewer.
^ ' OH33 in. per hr. 39th St. sewer.
• '^ ^^2'> "D. per hr. 63rd St. sewer.

* Ktkl. in districts provided with separate syHtom of w»wors.
• * Kal. in districts provided with conibincil «y«t«'in of hcwith.
mpix^jj pUnts and parts easily duplicated ir>0 «:»!. jwr day. DiitpoHul i)lant 75 gul.

'".7- »*•• -Uy.

H J^*^*^ VsUey figures are for sewer flowing full. Fi\?rin'M in report aiwumo iimximum
•wlth»c,w 3/4 full.

*^' supply reaching sewers.

186

AMERICAN SEWERAGE PRACTICE

its elevation varies greatly with the quantity of rain and snow wat
percolating into the ground. This is usually greatest in the northei
part of the country in the spring of the year, when the frost comii
out of the ground leaves it porous so that the water from slowly meltii

Table 55. — Leakage op Ground Water into Sewers

Place

Gal. per day per
mile of sewers

Extent of aewen
considered

Alliance, Ohio

195,000
41,000
86,000

264,000
45,000
61,000a

178,0006
26,000
32,500
30,000
22,000c
9,000
35,000
45,000
25,000(i
48,000
60,000
50,000
25,000«
40,000/
80,000
to 100,000
32,000
to 60,000
24,000

100,000
5,000

Altoona, Pa

1 . 2 miles

Altoona, Pa

0 . 6 miles

Altoona, Pa

0.95 miles

Brockton, Mass. .*

2,000 ft.
10,400 ft.

Brockton, Mass

Brockton, Mass

10,400 ft.

Canton, Ohio

11 miles

Clinfon, Ma88. ,

CJoncord. Mass.

whole system
29 miles

East Orange, N. J

East Orange, N. J

25 miles

Framingham, Mass

whole system

Gardner, Mass

whole system

Joint Trunk Sewer

150 miles

Madison, Wis

Maiden, Mass

whole Bvstem

Marlboro, Mass

whole system
whole system

Medfield, Mass

Metropolitan System

Natick, Mass

137 miles
8.58 miles

New Orleans, La

North Brookficld, Mass. . . .
Peoria, 111

1.41 miles

Reading, Pa.

Westboro, Mass

Woroostor, Mass

1,072,000
32.000

3,010 ft.

a. Water in river low. h. Water in river high. c. Great precautio
taken to prevent leakage, as construction was carried on in quicksand ai
the ground-water table was naturally 10 ft. or more above the sewer.
This relates to the sewer serving parts of Newark and Elizabeth, N. J., ai
snuillcr places westward to Summit, e. Before house connections w€
nuide. /. liefore any connections were made.

The Maiden figures are from Eng. News, Aug. 27, 1903; the Conoo
figures from the 1900 report of the St^wer Commissioners, and the remaind
from reports of the Mass. Board of Health and Trans. Am. See. C. 1
vol. Izxvi, 1009, 9t 9$q,

QUANTITY OF SEWAGE

187

[IraporfcM

ice and from gentle long-continued rains niay re^Kiily per-
throiiRh the upper strata which later in the year form a hard
pwropaf t cru-st more nearly impervious.

It iu often held that sewers which at first are porous or have smaU
cridwftnd poorly filled joints will gradually "bilt up/' that ig^ the pores
will become hUed wnth particles of fine clay and sand and that the leakage
will thiAs he reduced. Trenches also become compacted and if in clay a
nearly water-tight byer may be formed around the sewera, thu.s cutting
^off llie wateu- m that it will not follow^ idotig the pipes? and enter through
■feet jonts. The^e obaervationn are all more or less well founded,
tli als<i a fact., and this largely off set,s the foregoing causes of reduced
that many times the i)ipes crack after being laid and that con-
|fioelkia« made from time to time are so poorly constructed that they are
> fiource of great leakage. Abandoned connections are rarely scaled
it the (Mowers and may admit much water. Manholes are '^heaved"
r liin frost 90 that water may enter between the eourse^. The net result
^ these changing conditions appears to be the presence of a gradually
ttfig quantity of ground water in the sewage*
the water does not usually percolate or leak into aew^ers entirely
F'ifwmd their perimeters, but rather enters near the water line, it seema
iarfly logical to report leakage in terms of area of masonry surface, of
^Jnifth of pipe joints or even of radius or diameter. It is doubtful even
^V the Q[itnl>er of pipe joints per mile throws much light on the subject,
^B||ngh the chancers of poor joints in the main sewer are proportional
^^Bv number of jointi*. This, however, takes no account of the leakage
tbrough house cooneotions,
Dtta are most easily obtained in terms of quantity of leakage per mile
' i&wier and the moet leakage may come from the smallast sewers.
' ^ u this unit, it may for convenience be etilculated in
- 1 L and quantity per aca-e, the latter being probably the
*l convenient form for use in plamiing intercepters and trunk sewera
' trHf^ii fi»r pumping stations and treatment works. For detailed
•nH of email lateral sewerc*, the quantity per capita is perhaps
u^t^i -cd.

Thv . ,._ _ lieUcve that an effort should be made to secure data in
tloMit ihcms thrw* terms, gallons per mile of sewer?, gallona per capita of
I residing within the district served, and gallons per acre of
:'t.

ACTUAL MEASURED FLOW OF SEWAGE

I 56 are given stjttisiirs of tlio sewage of a numberof Maasar
ties and towii--(- Tin ^o communities all have eewerage ays-
I the ^mpfirate plan and the flows are oonsequently unaffected by

188

A. \f ERIC AN SEWERAGE PRACTlCi

140

m

m
no

too

90

80

70
130
120
110

too

90
B«
70
60

I 2 3 4 5 6 7 8 9 \0 IM2 I 2 3 4 5 6 7 8 9 10 n 1? I

k 4.

t *

nours of Do/.

Ftu. 66, — Hourly variution^ in flow of sewaj^r ul vuh-hj yu

Worcester, Mcksa. — Efttimai^xJ populuttnn. 150,000; avarug-e dry wvulUftr duw, IsJ
ftal.; 1) huui^ iR'riod of flow from r\\\

TarotjUi, Otji. — Dry wo»th<:r f?* ttntc^ni^ mtktUf in <»iiy, lU

NovemlitT And D♦^cl•mber: from R' ; ^

OtlwFTibu*. Ohio. — DUcbttrife of n ivtnr riicu«ur«nirntji Hi ibeo

!>,.,. 2-0, 1904; nver»ge wcok-iJny fio^ *lur4Jni 4.iunna> dry wrath^r - ll,4(ll).000|
cwUinui(*d tiopuiation in 1901}, 1 50.000; Irurn «fcma*ikQ'« K«'|»ort nu runflrntkut «4 ioltii

riiy A uiwme niupt be omitted for l<*ri»l r»ii*niie), — From miy to fmU<«t i» «bouidJ
pcrifHl of <Vf*H : jmpuUaion, 15,000, typical ttv#»T*go dry-weaUwr flr»w in Jtjjj uml *

Bifh nut works; mutiufn^ttaHu^ wnuiitMi Aban

of dr\

(Jlov (' 20 2 p*r mux, of toUl flow: nomtUtid^

Hver^iiCf^ tiuw 4:«oi;4i.iMU} ic»fcl djMiy; ttiMiiu4c» ftt «icpaniueiii •utlan, with b»iI*hoar \
flow from cUy; Veu 30, iSKm.

130

r

-5

^'^

7tO

t9

>c:

ISO

flQ
1 f>f\

fc

^

/

C

\

s

^

L

r

*.

S

|x

(^

\

%

S

<^0
80
70
f30

m

V-

")

■%

t

S

Ik

i

Ud

5fA

7er

Ma

■21

5rt

1/w

met

n:;

141

>

t5

2^

'A

J

^k

■^^

\

s

1/

n

w*

W

\

^

1

i

f

^

h

Si

\

Di

tcfv

^ 1

Coirt

u

f

^

^

s

V

100
90
80
in

7 /

1

\

5

\

1

m

^

^^

L

J

If

her.
ffHt

fer

w.i:

r/?

79}

^iS

S

^

'm.

7^

f

r

N

^

CJ\

i

^

Sj

%

^;

i^n

s

^

>^

/

QUANTITY OF SEWAGE

189

I water except a^ it iiicroai5e« the leakage and the improper discharge
Kurfaee water. It should be noted further that they are
from small communities without large quaiilitiei* of trade
. md that the amounts per capita are much smaller than those to
idlNicted in large cittea,

1 different result is to be noted in certain sewer districts of
■ > t; t m1 in Table 57. Thc^e sewers are on the combined
Hi iremeuta were made during diy weather when the

I prowimably eontained no gtorrn water, The excessive flow in
lewdm h to l^e aocounled for largely by the great consumption of
met in the city, which in IQIO averaged 242 gal. per capita of the
popabtioa*

Tabui 5(S. — Maximitm a.vd AvEaAOB Flowr of Sewage^ 1903

fMA««B«tiur»cClB 8tule Bounl of IleftJlh)

AvttTntte yea

fly ijUAUtity of

Avenvge <iut»niity of aewagcj

tioa

sewage

in miu(, month

CSallon*

•mr 24 tiourn

OttUona

fvur 24 hours |

PWe

P^r

con-

Per

mi. of
■twer

Per

in-

hftbi-

Per

P0T-

ion
eoon

Per

eon-

Bftfi-

ttoti

Per
mile if

^^k.

17
90

»5
36

2»0
612

II.IMJO
20,030

K,.

31

65

700

41.000

t4«9(K»

62

78

528

40,000

78

117

787

00,940

^Kii

5,038

63

2W)

1.311

41.430

77

370

1,012

60,42<1

^H^^^ .. . .

I2,»7ll

$3

87

537

41,400

78

120

700

01.400

^^^^^^^K^

86

1,090

37J50

101

2,032

70,375

P^^^^

llpTOS

47

K(aip^4» tf « .

60

714
750

33J80
37»500

b|MU»

*2,S13

00

76

11,522

«

60

42W

14,020

1^..,!.

j:.'.7ki^

m

110

mi

•«5j:iO

169

2r>3

1,274

83.800

B

'>.S03

67

143

803

rj2,400

H3

280

1.706

lO.'l.filo

B"

IJM^

(16

07

707

45,030

mt

ia»

8M

1*1, _Mr!

MMbtfiitfi<

u,imi

32

169

1J(J8

01.400

N^f

7,««5

iti

125

026

37,500

lM4|k|»|«*

2«0ft3

M

04

700

21,430
3«.000

^mUnmig%

&AP9

51

\H

1,<M}7

UH

100

2,030

78,760

Vimtiocift in Flow. — ^^The flaw of newage fluotuales between wide limita
billow« «o]n€what the variations of the consumption of water. The
loir 19 ali*o mofoaaed by the greater discharge of manufacturing
at tiiat time. During the spring or wet months, the flow w in-
^ Mind wntiir contributed, some of whifh

rage systems. In Fig. (>4 are plotted

iif newagc m tanns of [lercentaga of the average, from a number

..... M I _ ^^j^,jj niade to Rvnchronixe the ounces by umk-

L' required for tlie sewage to flow from the city

190

AMERWAN SEWERAGE PRACTICE

I

I

I

to the gagiug; jwint. The curves on the lower part of the fifomm i

typical of dry weather conditions when ground water is at a mminiu
while the curvea on the. upper portion of the figure are typical of oonditi
when ground water is relatively high.

Table 57. — Typical Drainage Areas and Drt Wbathbr Rc3f-<

Chicago, 1910 and 1911

(From Wiiioer't Report on Bowc^go DiapoBul. 3an, Dint, of Chic«(|o, IPIII1

1

1
1-

is

■3

3

Dry weather run-offn,

'i

'

3

Sewer ouKalU

i

i

If

5*

1,

11

Pexiod e«*>w<l
by obwrftku*

1

1

5

s

6^

CD

1

Divcreey fioule^

ago

23,550

8.eS;0.00»7; a, 32

238

2ftr4

Aug. 15-17, m

van! (W).

2 cliys.

Randolph St. CW>,

340

n.35g

6.10

0.0254 10.25

348

47 4

Aug,. » aAyit

Uobey Si. (S)

2.6OU

asj2S

10.1

0.0040 2,5S

160

15.5^ Juno l-^ m}M

d*y»^ fl

A»lilaDd Av©., (8)..

i>aQ

44.5SI

23.2»

0.0237

15.1

338

48.6 ^1iiy1S-30,llll|

aday. 1

Center Ave., (S)..,

oou

23.4«i

30. 0«

0,0317

20.3

678

35.0

May le-lSt Wit
2 day*

Thirty-miUh St,,

1^340

285,900

140. 0«

0.0008

6.25

318

20 0

putnpiriK 9t(%l4on.

100.0* 0.0070

4.4tt

237

200 4Uyt
Ai«.l, IW«

Ninety-eecond St.,.

08

3»9eo

1.810.0188112.0

335

37 4

1 M*r. 31, l"«i'

'iuiE. l>lii»i'

Wfiitwortli Ave.,

6>3<)0

30,464

12.4 0.002.1

l.5»

2W

5 8 July31. l»Uj

(«). fCftlumifi),

1

1 25.t fUw J

1 Dolly varidHioD uv^ruKe

8 A.^f, to 8 P.M. 28.6 ei.p.8. contAiiui Inree amoutti of mduatrul i
8 P.M. to 8 A.M. 18,6oXp.»,

• Daily viiritttion avcnico

8 A,M. to 8 P-M. 2.^^.7 c.f.p.i. coalaitiA liiriie amoatit of iDdmiriAl «iriiJii«.
8 P.M. to 8 A.M. 17.0 c,f.p,«.

• Thw run-off or mor« for 76 dnyo In 1900.
< Thin run-oifl or more for 270 days in IWOO.

• 2.4 c.f.p.«. per square mile ot'currtsd 339 day« in th© ycnr.

Two curves are shown in Fig. 55» token from thtt report of thoS
Dispasal Commission of Milwaukee, 1910. The dotted Uin
the flow from a large residential sewerage district in Milwi*
smooth curve is drawn tlirough pointst obtained by averaging pomu t
from several cur\'ea representing the flow from the cities named ioj
note accompanying the illustration. In this case the otir\*ej»
&ytichroni7.ed juul an effort made to produce a ourve t>'pie&l of the fiu
tiomi in flow of the i^iewage from the larjs^er citiea,

Obviously the fluctuations will bo gamter in single lines of 8cwersv <
■||i«mw.1l district!*, than in trunk and intercept - - • ts serving Uq^e aroi^

^ QUANTITY OF SEWAGE 191 ^^|

Thofact that the tsewftge requircji a longer time to flow from rertain dk- ^^H
L tnctt tliau frotH uthem ass^ists in prcxlncing a more nearly unifonn flow in ^^^|
Ltbe iutcnH'sptiiig wiawt^rs, m l** evidimt frttm Fig, 65. ^^^|
H The flow on difTcront days of the weeics varies considerably. On ^^H
Btiyby thft quantity ia smaller, and on Monday larger, than on other ^^H

tno ^ ^^^^^

' rm

1

i M 1 1 M M 1

. FyU tine k Awtaae c^off Gaatnas,.

;/

\

'}aftn^ . PtJtrfCf No. 4 7
hmfs ihiMm thus m

1 1 I! J t 1 t 1 « 1

<

/

\

1

]

rA

,

f

1 iTA

.

^

M

X
^

I

/

j^

n

&

Ik nA

1

/

A

^ "CO ^

\

1

"^

IV

8 'lO "

r

^

\

i"

\

s

S

J"

{ ID

J^l

'

\

^

/

^

s

J

\

i*.

s

s

7

>

w

N

^v,

•^

^

^

i-^

r''

1

1 1 1

\

1^ 5 6

loiirly

7 8
AM

3 fO II R ! Z 3 4 5 6 7 8 9 10 H II 1 \ I

- J<— - -P.M." J

Mgurs of Day
■iatinn in flow of sewuge in various cities.

I "

'• ly.

1

w

■

00

ili
tit

■

L OnM

he «crmo
Usd to giv

on

alw
d
e i

■

ia.

ou
cit
ta

■

M

r t

L J

y

na

■

he

*>,
A
ni

■

n

.^.
KX

in

1

-n 3 1

It*
1

tl

tl

3t
Till

d

le

yp

at

lidc

nil

1 i
Idle

nu
ur

m

ini
ve
?iv
af

fl

of
•en
I 1

ii
.he

13

Wl

1 J

1

iiij]
•ve

US

Kifi

iUt

Kill

mv

cur

K

ua

. i
ht

>W

192

AMERICAN SEWERAGE PRACTICE

The rate of infiltration of ground-water varies greatly from season to
season, but does not usually fluctuate materially from hour to hour. As
the proportion of ground water increases, the fluctuations in the tot«l
quantity of sewage flowing from hour to hour naturally decreases. This is
illustrated by Fig. 67, showing typical cur\'es of hourly flow of sewage
at City A, with flows ranging from 300,000 to 1,180,000 gaL per
day, the excess of the larger flows being due wholly to ground-water.
From similar data the curve given in Fig. 68 has been prepared, illus-
trating a method by which it is possible to calculate the average rate of
flow on any day when the flow at a given hour in the day is known.
While this cur\'e is not applicable to other cities, it illustrates a con-

I

5

t .

6 2

130
\10
110
100

^

o

70

60

50

«f

fd^.

[-

^

■>

A

y

f

2

'i'p

1///

—

-^,

**.,

a

to

*r

\

'S=

y

.^

^

p

^'^

^?

"■^

""*.

\

^

\

■

;

N

s.

^

V

^

T

fhu

rj{3

PPh

rfu

Nof

ihi^

^17

^0

fttOi

stn
turn

cfo

^¥

-

%if

fhb

hfr

iqM

fita

nC

urirt

fm

^

3tk

'Hin

I 23456789 10 II IZ I 2345678 9 10 II Itl

k A.M.— -4c - P.M.- >l

Hours of Day.
Fia. 65. — Hourly variation in flow of sewage in Massachusetts Metropolitan

Districts.

venieni method of obtaining fairly reliable records of the average quantity
of sewage, by single daily observations. It is not as satisfactory as the
use of a self-recording gage, and should not be employed where the latter
is available.

RELATIQN OF TYPE OF DISTRICT TO QUANTITY OF SEWAGE

The quantity of sewage to be expected from a district depends uponita
character. A residential district will produce sewage made up of the
household wiistcs and the ground-water leakage, the former being
governed by the quantity of water consumed, which will vary from W

QUANTITY OF SEWAGE

193

^ capita in the lowest

dSlEi ' to 75 gaU iu the iirst

rila» ...,. ...;.^?i or to 135 gal. in

I

tl«irlmcnt houses, fia shown by

Table -IT, A mercantile or com-

Bi^imial diJJtrict will yield a much

ptjitef quantity on account of the

great office buildings where water ia

iwcd for many purpoises, such as

the oixiration of lavatories*, motors

ml elevators. The flow from such

(ii5triet« will consist of the used

i^ater from the municipal supply,

tbc lerouiid-water inliltration and in

fts the used water pumped

_ .i^, which often amounts to

qUAntiiies. Manufaettunng

indufifrial districts may contrib-

ickrge quantities of liquid wastes.

of this water w taken from the

ipal supply but frequently very

Wgc (juan titles are taken from wells,

trs, lakes or even tidal bodies,

J»ewage from such districts is,

eftire, moile up of the used munio-

Kupply from residences and in-

itrijU establishment^^ of the used

KUfipUes of the manufae-

and of ground water. On

liiuid districts comprising

&ml cemeteries contribute only

poiuid water^ as a rule.

Clt8si£aition of Areas. — A ra-

•"mjil cla«afication of areas in a city

^ ft mait42r for czu-eful stu4yi due con-

"'* ' ' 'U to such natural

-mphy and pruxi-

-.,. lakes or tidewater,

i L J a.:, ^irtifiicial conditiona as

^^Anmd and ittreet car linen, docks

«Mlc«niib, Tf ■ ■: iota

•«»Byoecupv i>c^

iopoicmphjcaily unsuited to

worka. The commercial

7

'^'

o

S
a.

Q e

a. J*

Q ^
O *
O o

. II

t 11

I S' I g 8 g"

•f^. <^ p. F SS N,

S 9

5 3

I "^

^

^^V 194 AMERICAN SBWEHAGE PRACTICE ^^^M

^^^H or mercantile districts occupy the more level areas in the **cent^" djH
^^^H the commimity, usually convenient to railroad terminals and docka» and
^^^H contain public and oflfice buildings, retail and wholesale storeys, depota
^^^H and freight houses?, hoteb, theaters, and generally aome apartment houses.
^^^H The commercial area is usually relatively small, and while provision should

^^^^^^^^h Hour^ Day.

^^^^^^H _J? ? 4 £ 8 (0 11 1 4 6 t 10 fZ _ _ ^M

l,6QQ,000 ^H
1,^00,000 ^M
1,400,000 ^H
»,300.000 ^M
1,100,000 ^^

t,too,ooo §

o

1,000^)00 o

c
900^00

«0,000 ^

0

700,000 •

0

600,000 *
500,000 ^M
400,000 1
300*000. ^H
?00,QOO ^H

3

J

00

>

"^\Mtf7* 86. SX

/

r

N

^

N

s^

C-

^^

V

r.//5.
. 55.

OZ-

^■v

J

'afwf

OOS,

000

^

'

\^

\

.

r

4 /QiT^^

Majf. /275t J

/'

\ t

^^. 7S.

^r

)

^

^^-

k

s

J

/

1

^^^

^n. 50.0 Z

,Tut3tS0ptSOj/9/3 .

<

/

A¥, ffatt 360,Ch

1

QO

^s^i

\

N

/

^^^H be made
^^^H too lorgf
^^^H areas arc

^^^^^^- water su

tl468lOlZZ460lOr

AM. f.M.

Hours of Doy.

—Hourly fluctuatiuna in rate of fli3w of sewage c^nta
prut>ortioi3is of ground water.

for future growth care must be exerciaed to prove
s an area, for the unit quantities of acwage are larg
J genenilly located on fairlv level ifii ' ' r'
ur tracks and sidings nmy bf» hnH.

are likely to be locat

pplio^ nntv \it^ liJiiL

ining diffewS^^
mt estinuil^H

^^P QUANTITY OF SEWAGE 195 ^M

Pliilftdel{khia Sewer Gagings. — Gtiginga of the tin' weather sewage ^^M

flijw frcMD Philadclphiii tliatricts of different t>'pes of development were ^^M

deicriWl in the annual report for 1912 by Mr. W. G, Stevenson. Some ^^M

of the data procured are given in Table 58. ^^M

Residential Districts. — In computing the probable quantity of sewage ^^M

^K)m rt>idential district's, it h first necessary to estimate the population ^^M

^^pc.li, Ut rrside in thein and decide upon the number of peri?ons per acre ^^M

^Br which provision should be made. In <loing tlds it in not always safe ^^M

PVd ftiutime tlio same density as that estimated for the entire city, which ^^M

[ rarefy run* over 25 peirsons per acre, according to Table 41. The density ^H

E ^"

^B in a particiik
^■Btsctonhmia

^HdlMsmii/'
^^■■tal 1U uri«4

i.eoo.ooo ^H
l,!»O0W ^H
1.400,000 ^H
1,300,000 ^H
^?00^ ^ ^H
UIOO^ t ^H

900,000 1 ^H

800^ ^ ^1
700,000 ^ ^H

*

o

\"

_

fl

V

J

jt

a

\

D ^

9

'

e

\

0

<

a

■i
01

\

a

1

i

\

* I

1

; J

S;

<i

'

a

"J

0

H

a

a °
(1

o

*

^^

n

.^lu

306,0"% ^H

?00,OQ0 ^H

^ 100.000 ^1

w per day in a city ^^M

nple, one ward in ^H
^ are in mast large ^^M
copulation greatly ^^M
readily calculated ^^M
maximum rate of ^^M

rs ser\*ing residen- ^^|
the general direc- ^^|
art men t of Public ^H
'he gaging^ were ^H

)0
Per

ioc

rd

der

ISC

. MO i?0 130 140 ^ (50 160 r
C«f»t %(r«^.<h 4 Pli.Rote i* of Averoge f Iwrfof +h* Doy

f flow of sewaRC at 4 p. m. to average flo
of 15,000 population,

istrict may run much higher; for ejcat

i8ity of 190 in 1910, Table 42, and then

in which the density of %

' *\v from the district k now

cmity of i>opulation, allowancen for

^ and maximum rate of ground watc

1912 the flow in a number of sewe

■

■

■

■

■

w

■

ait<

5. <

'11

2hi

of

ef

the

■1

ep
1

QUANTITY OF SEWAGE

197

"\% 2 4 6 8 10 12 Z 4 6 8 10 I?
A.M. — 4c- P.M.

Hours of the Day.
Hourly Variation in Flow of Sewage .
Curve A. Ross (bloody) Run Scwcr.

69 1-765 I

o o

46 510

69W"fll900
74% 1^^93250 5

5990

|-74600i

1^ ^ 4 6 6 JO fZ t 4 6 6 10 t? 2
(♦ A.M. — ->|< -r- — P.M.- >1

Hours of the Day.
Curve B. Vine Street Sewer.

4490^ '55350 g

I? 1 4 6 8 10 17
h^— A.M.— ->£c

2 4 6 8 10 12 2

P.M.- >I

Hours of the Day.

Curve C. Marshall Ave.Sewcr.
FiQ. 69. — Hourly variations in flow of sewage, Cincinnati

454 ^mi\ ^

i "

363j--68?9i

27Zg 5IS7 :
3

I

.5

198

AMERICAN SEWERAGE PRACTICE

will be seen that the maximum rate of flow must be expected to reach
from 160 to 170 per cent, of the average for 24 hom^, and in the Hoas
Run district the maximum gaged flow was et^uivaleut to 254 gal, per
capita per day. A conventional or typical curve of flow is shown in
Curve A, Fig. 69, and the ratas of flow during the day are given for
both residential and commercial districts in Table 60.

Tabi^ 60.— Rate op Sewage Flow fob each Hotm of thb Day, H
Percentages op the Average R\te, CtNciNNATi, Ohio

Time

1
1

nets

*

iDdujiri*;
Difltrici

h

1^

1

1

>

1

1

i

|l

i^

1 A. M.

63

75

33

71,

55

60

42

38

77

72

69

2

58

73

31

71

52

57

41

36

77

72

60

3

53

71

33

71

50

57

41

34

77

71

61

4

51

70

35

71

50

58

41

34

80

71

63

5

52

72

40

71

55

60

41

38

84

72

66

6

64

80

53

75

66

66

48

49

89

76

81

7

112

105

74

96

92

85

67

97

100

93

105

8

162

153

126

139

144

128

145

151

118

113

129

0

171

162

171

147

156

141

174

170

130

126

134

10

167

156

190

147

158

148

175

177

134

136

138

n

167

138

191

140

154

150

174

180

137

139

140

12 Al.

148

123

190

135

150

152

173

178

137

139

141

1 p. M.

139

114

185

128

144

152

171

174

132

137

141

2

128

108

180

120

136

151

169

165

125

136

141

3

118

105

172

116

128

147

168

153

118

131

136

4

109

101

159

109

123

136

165

140

107

128

126

5

102

98

136

102

113

118

155

124

100

122

116

6

04

95

107

98

105

99

89

106

96,

108

105

7

88

92

72

91

97

89

71

90

86

89

94

8

82

89

56

88

91

81

62

75

84

80

86

9

79

86

48

85

82

74

53

62

80

72

80

10

74

84

42

81

75

68

47

52

77

72

73

U

70

80

39

75

66

63

42

45

77

72

68

12 P, M

m

77

m

72

61

m

42

40

77

72

63

•v^nic^ or CQJiv
b^en iaduded i

piiiioa»l eurv«B for
n pr«p«riiic tJka»a c

Thf«B ficunw bfcv(» b«<!>n comput<»<i fram the
am^rmtmi a*ir«r dUiriou. Sunday flow bM ciot
voivtloiukl eunrM

Mercantile Districts. — The allowance for used wat-er from a merca

dtstricl Ih niurc diflicnlt to cstimn^ * ' ■ hat from a residential dist
If tho mtinmt<» i*» in ho mwio in i with the design of tntt»ro

t< n>e.^ the diHtrict .'

t _ u gage the flow In |

QUANTITY OF SEWAGE

199

$md then allow for such increase due to future developmeDt as may
appear lo be wniTantcHl. It may also be possible to make a water supply
mumf \ming careful to ascertain the quantities of any private supplies.
■ Some aaaistarice may be derived from ditta obtained by the Cincinnati
^^jE&giiig?c The Qommerieal district of Cincinnati is located on the plateau
^Myh^lp of the right bank of Ohio River, and is traversed by parallel
^^m^Pbning north and south in which the main sewers were built
' ilfty ycar^ ago. Each sower ser\^es a rehiti vely small area and discharges
directly into Ohio River. Vine Street is most highly developed, and
I'perhaiM, may be said to be the center of business activities. The
becomes leas and less higlily fleveloped toward the east
ng into residential districts thickly built with apiu^tment
i ai ii^fleeted by the density of population shown by Ta!)le 61*
sewers in this district are generally above the water table and
^iaJiltnition in material quantities may be expected only at seasons when
I water is unusually liigh. Measurements of depth of flow at the
i of nb«xrvation were made at frequent inten-als througliout the 24
pwtr* and tixterided over one or two days in each case. The average and
jmiximum rates of flow per acre and per capita per day are given in
tT»bk^61.

V ^^ flow var>' greatly from hour to hour, due to the way in

whir,. r is used. The districts are so small that these fluctuations

I irt not Ntnoothed out as they would be in large districts or in an intercept-
jfagiKjwGr. From the gagings conventional curves were plotted as rep-
JTr^ntinK what might be tenned tj^pical rates of flow, the resulting fluc-
I tnarioiw being given in Table 60. The curve for Vine Street is shown
Curve R, Fig. 69.

'Tttti fli, — Av£nA<iE Flow op »Sewacje from CoiaiBRCfAii Districts^

('(vriNN'ATr, Ohfo, 1912

- ■,^ iim' flow from .actiml

No, of

ih««fdi«irU

Afwi
in

I'optiUlioQ

tfaeitiKN

cover-

Dates of

G^, per ucrtt

OuU. JHT Citp-

h

9fitm

pwcUy
Aver- Mtixi-

ita p«r d&y

tng 24-
hour

«Ji«inE»

Tot*l[ D.I1-

Avor- Maxi'

1

lr»tt»we m. .

1 -Hy

RCe mum'

aB» ! mum'

d*y

37.8 IJ02 ftl.2

25,g00j 70,3(1(11 421 I 1,245

I

Oeu 30. 31.

■i^"'

IH.fi

4S7 2nj»

37J50j 88JfJ0| 1,435 ^ 3,350

2

Oet. 20.30.

^V*

J I* 3

3S0 13 0

eSO.OOO 135,0(K) 4,010 i 10,300

I

Nov, 2.

PP

i » '^n 12, A

72iv<»i !o»-i,M» ajso IIJOO

t

Nov. 5.

MX,

17-4

4S,J 2J77

5,150

2

Nov 15. le

37.7

40.H > l,0«0 ,

2,150

3

Nov. 8, 0

^.

A* 9 i.iai 41. T UJiM\ iia,MHi\ 352

845

I

Nov, 12,

i\

2HA l,f»7U AS.rt

22.050; ;*«,400^ 30ft

0«O

a

Nov 12* 13

i

lmu»,fu 't

m 2 7.5mI a.1 a

4ai<yn S5.344' iieo

4.5mO

i

1

1 ;

'VMtawn aliiriM caRtnii tMriod.

■mtt

200

AMERICAN SEWERAGE PRACTICE

Industrial Wastes*— The amount of industrial wastes not originating
in the public water supply is subject to wide variations in different citiea
and is a nintter for individual wtudy in any particular case. The amount
of 8uch wastes may be large in some cities and even exceed the volume of
house sewage. The amounts of these wastes have been investigated or
estimated in a number of cities and the results of a few of such studies iire
given in Table 62.

T.\BLfci 62.— Estimates of Industrial Wastes

Entering Sewers

City

Giki. per oaptta per day

Dale of C9tinuit«

Milwaukee, Wis

57

wn

Fitchburg, Mass. ..........

81 (max.)
2H (max.)

1911

Passaic Valley 8ew<?r

1908

Louisville, Ky

57

1906

Paterson, N\ J

13 (max.)

1906

Providence, R. I. .**,-* ♦

42 (max.)

Mass, Neponaet Valley Inter-

25 (max.)

1895

cjepter.

Cificinnati, Ohio. ,...-...-.

■^

1913

In Table 63 the results of gaging one industrial district are given.
This district contained both residential and industrial areaa but in typical
of many sewer districts in industrial centers. These gaging^ extxindcnl
over 3 days and the maxinmm rate of flow found was over 13,000
gal. per acre, etiuivalent to over 700 gal. per capita. The hourly flucttja-
tions to be expected in this district, taken from a smooth cun-e based on
the gagings, are given in Table (iO and the cur\'e is shown as Curve C m
Fig. 69 .

Tabls 63.^AvBaAOK Flow of Sewaqh from an Industrial DiaraiCT,
Cincinnati, Ohio, 1912

Suwirr ilijilriiL

Area

ID

'PAnit

-.; _

B(?wago flow Iroin nciual

Gftli. pet mcTv G ab. per cftp-
par day ita per day

oover-

inK24-

bour

day

D«u» of

Total

•ity

Av«

Mat»

Avg

Max.*

Mmnb&llAve...

204

Mil

IQA

678T 13,485

35d

70S 1 a

Nov. m.

27,30

I Maximum iluritig ^gitig period.

Estimate of Quantity of Sewage from Entire City. — Having given

cothsideration to the population, area and average and rnaximuin rales of
flow t-o bo expected in residcntiab mercantile, industrial and park districts^
it is next neceiisar>* to combine tlie fliflferent elements to arrive at an
estimate of quantity of sewage for wliich provision should be made for
the entire community, or a portion of it which may be served by a trunk
or intercepting sewer. It will simplify the cxpUination of t\m method of

QUANTITY OF SEWAGE

201

^•1

^a

C9

9

a

I

H

QQ

s

o

h
O

a

I

s

I

a

i

9ii|pnpzo

ki

kU

m

M-O k I

5-2

a-c

85

,1

m

lM9«

jad raotiad
X)|*aaa

<

is
o

3
3
3

d

o o o o o o

1^ Q oa c^ o ^
lO O "^ "^ CO OS

o g g o e>

00 t^ ^ r^. -^
O c< r^. CO CO

OCOOOOI^COOOOO^

to oi oi O O) lO O O to O O
^^CO'^COCOXCOC^'H-'

XCOCOtOi^"^005?i«05t^

i^,-i,-i,-i,-ic^coe5coco

X 00

1 ■

O 05 T}< Oi t^

'it^ O CO O CO

1-i

M

M

CO

c^

o

00

CO

to

1-i

-^

o

o

o

o

o

c^
c^

c^

o

«-4

to

1-4

c^

X

to

CO

t^

g

o

i

"^

00

00

CO

to

*H

o

a

■^

O)

t^

SgiC^OtOT}<coi^x«oeo
^,-1^,-1,-iC^COC^COCO
^ lO

COtOtotO'^tocOOSO'^'-'

^* 05 csi csi T}< -^t^ to "^ oi -1 05

i^COCO'^C^COl^'^-'-'

CO

SX O C^ O — < X
c^ to o -^ c^ o

CO 05 Oi h» tO ^ CO

XXCOtO'-i^OOi'^Ob*

8' gi ci d to "^fJ CO 1^ X
^^^,-i^c^coC^

CO CO
CO CO

J

O 9

I

M SQ (Ih ^ H^ 0Q

§ CO

8 3

O ^ C^ CO "^ to CO
lO to to to tO to to

l^ X
to to

o o

to CO

To"

X

s

CO
00

CO
CO

J5

o

s

00

to

s

o

CO

X
CO

CI

CO

to"

.2 C

•c —
^ o

O X
JO o

202

AMERICAN SEWERAGE PRACTICE

1

5§

E ^ S

^1 s*

•< = — - — —

e * eif S E 2

l^ -r 00 O ?? r* CI W -^ *0 't'

— I O 1-^ « ^ ^ CO lO »>- '35 »-

'T c^f cf m' CO «r 'T fc^f i-T «r ^

"^ fo CO CO TO ro CO po 00 w po

d M b d d d -^ M *-•' ci *h'

-5

^ac 2? « » QC X cs C'l aC' 'X c^
dodddddd^i^p-i^'

CO

O CC ^ O QC

1:0 Ci W CO 55

»i^ 1^ ca CI o

d ^ d -^ ^

OD ;o «-» 'er !S> Q 'X <M tQ f CO

d w d d d o o o c Q o
tr ^ O 5? ^ ^ c*i CI CI CI CI

d o ^' »c ac CI X o c:- »f^ -s*
CI 1-0 5 C! r -H CI ro o O' o

docodododdGO

O 01 dft -^ 05 t^

-* 05 13s CO p eo
— CI cj CI 35 CI

"S —

if

o ac CO lo -^ '^ O c: o o o
CI -^ ci d 10 f* w ac 10 to t^

CI

gdcio»o-9'di^g&d<«

I

a

I

s:

? o o c o c o c o o o

- 5 oa CI o 'f X t- »- t^ *r

c o ^ ^ ts c: o CI r^ CO CO

Cf CI

- C 3D

8 ^

Q f. ** *i

i

h

h

II

5, «.

QUANTITY OF SEWAGE

203

Saadsen-e to ftummariae the whole disciisaion, if an il!ti»tration
actual prmrtic© b gi\'en. For this purpose the studies made
I rinoiimati, Ohio, in 1913, already alluded to, may Im taken. Under
thr t5nnditions tliree main intercepter di.stricts wpre decided upon and
ft^lynjitmi as the Duck Creek, Ohio River unci Mill Creek districts from
imiTH^ of tlic water-Gourses along which the interceptcrs are to be
rtructed*

aving lifst studied the local conditions and estimated the probalile
111 of the city a-s a whole, l>oth in population and area, during the
"economic period of design/* consideration was given to the
of population and area among ths several sewer districts.
t*e areas, as dictated by topugraphy, were indicated upon
urcd with the planinieler. A large map wa.s then pre-
: li were indicated the outlines of the re*sidential, mercan-
^uml mdustrial areas and parks, railroad yard;* and cemeteries. The
►»rtum8 of each coming within each sewer district were measured and
[ taliuljilwJasin Table 64, together with the estimated future jiopulatinn.
ition was next given to the quantity of sewage for which
L ihouhl be made, the unites of maximum rate of flow in inter-
^\ik»fs adopted after a study of local conditions and all data available
tttncghren in Table m.

XmM W.— U^ffiT QiTAXiTiEs or Flow in Inteecepters AseuMBB for
CivriNNATT, Onio

' ' u»(l water

^i-^,„r:... .......

[ ^'< nt popuhition) . ,...,....

^L M<i,M.Hi.M, aiiowancc for character of
^1 4*vt<1upmetit.

W Cr,,.,,. ■

I ^^^gf.

iter. ...

13i) guL p<»r capita per day
750 gal per acre per day

136 gal. per ciiplta per du
40,000 gaL per acre per dav

750 gftl. per acre per day

135 gnb per cjipita per day
0,0<X) gab per acre per day
750 gal. p<*r ntrre per day

750 gal. per acre per day

^^i»? i?*ulU obtained by the computationa are illustrated by Table 65

1 for the whole city in Table 07.

nay ^rve l^ explain some of the reasons for the units

in all cases are the laghest anticipated at times

;v^r>' to intercept the sewage or ultimately to treat

I Alio iufluttnced \yy the Rnioothing out effect of the difTer-

Ktleairatice of sewage from lateral aewers into trunk sewers

204

AMERICAN SEWERAGE PRACTICE

O
H

I

p
S o

t^ Cm

§2
»• a
a O

S p
a, I

Pi

00

c

o

9}

O

a

3

'1

a
o

o*

03

- *^ -^ CO CO

l_ § s.l

,, d o »o o

H

CO t>. (N

o »o »c

lO CO (N

a ^ cc

O) CO o

' -r .,

c
•2 I

I

4^

3 0!

X o

00 -i

rf 1? OS

' UO O 00
iC to 1-1

o c^ o

CO ^

^ 3 OJ

O

O !^ 00

^ ^ t^ '-^ o

a> • o o 't

OO j»^ ^ f '-^

o »Q

M* o6

o

'5 2

. 1^ <M O

c^~ 1^" ci

->c C^l C^J
' -^ X re

a •

and from trunk sewers into inter-
cepters. The ground-water allow-
ance is very low, because of the
enormous area and sparse population
anticipated, and because of the
topography, which assures the con-
struction of a large portion of the
sewerage system abov^ the water
table (luring the drier portions of
the year. These conditions ap-
peared to warrant the adoption of
a ground-water factor much lower
than the authors Imve dared to use
in a number of other cities.

The proportions* of the several
(il:LssIfifati(ins i)t fiow in the several
districts and for the t iitire city 4ire
given in Table 68. Prom these
data it will be seen that there are
great differences in the allcmanes
for the several interceptors, more
than twice as great a flow per a^sre
being provided for in the Ohio River
intcrcepter as in either of the others.

Provision for Storm Water.—
There is a general impression ibt
it is wise to provide in intercepti»l
sewers for a ismall quantity of storm
water, expreascxl often as being suffi-
cient for the " firt^t flushitip" of street
surfaces and sewers. This impres-
sion is based upon the assumption
that there are accumubitiofiS of set-
age sludge in the sewers and quan-
litK> (jf tittli on the streets which
will be immediiituly flushed into the
intercoj)tjr««: s* wi rs with the fir^
run-off due to rain. In some sewers
laid on ver>' flat grades and wher©
sewers have settled or have been
built with depressions in them, tiier©
may be such deposits, but wher«
sewers are laid on grades which gi^*
satisfactory velocities such deposit

QUANTfTV OF SEWAGE

205

bdieytid to bt» i!Xix?ptioual. Where depowiU wjeur they are generally
to consist largely of *ian<i and other heavy detritus which will be
, nloag otdy by relatively high velocitiea.

iix (l$— Estimated Unit Quantities of Sewage to be Provided
roil AT A Maximum Rate of Flow in Three Main Drain age
DisTiUfTs^, ah of 1950, Cincinnati, Ohio.

f^PCTTE-

— IftttuaUUl jkrwuit*?, hMeil upim WOO gal. p(*T ftcff* of iodustriril afen; mcrtjjiii-

■ ^%rir^ — (nuu«i-ri»i jw-'wjimo, i>a«<'tj \ip"" vvpiiu kui. ppr nviv %n luijutiiniii arpn, lueronw-
WBm «t«iMr»» upon iOifKH) gnl. ppr ncre of mcrrnntiU' ftrcii; itroiiml iriitvr, up^Jti 750
•kl p«r Acre ol WUl »rcti: itotuosU^ frewagc, upoo 13^ sal. p«r eopiva.

liitercept^ri< arc fed by trunk sewers serving rather large districts.
[lonnderable time in required to flush the major part of tho s>'stems to
\ tQternnpicrt during which a large flow is likely to reach them from
H'tions, Unle*!i considerable surplus capacity is provided,
, t4*'' n^ will often be running full before the flushings from much

^ \\m tnbutiir\' area c^n reach them. Therefore, too much stress should
tjwl Ik" laid on their ability to care for the '* first flushings," although as
w^linurily di^^igned they can accomplish something in this direction.
um! ' .' flow t^f «ewage in UX) gal. per capita and that

i^tcr i^ 3(X) gal. per capita, there wiU be a sur-
ivaiiable for*' first flu*<hing^'^ equivalent to twice the average
.- .^L% if Huch flushings come at a time when the flow ia at the
rale. The muximum rat^as of flow generaUy occur in the spring
r is high atid at other time*^ there will aiwaA'^* be .some
Furthi»rmoro, as intcnvepters are built for many yeaitiy
tWfr ifiii [^ j^ considerable excens capacity during the earlier years,
^W»f' 'iut rii. .i...,,i(i j^^^t usually be countt^d upon to care for storni water,
" ly dimini.^hing allowance accompanied by a gradually

m^uHii^ auid, if neci} tJujwy should be.

206 AMERICAN SEWERAGE PRACTICE

Under the foregoing conditions the sewage will be diluted to three
times its normal flow. Furthermore, consideration must be given to
tlie excess of water used in this country and to the quantity of ground
water which leaks into the sewers. With these eliminated the
quantity of sewage would be comparable with that obtained in
Europe. Taking all these conditions into account, it is evident that
the dilution approaches the standard of the Royal Commission on the
Disposal of Sewage, which is six times the dry-weather flow.

In view of these conditions, it was not deemed wise to provide capacity
in the Cincinnati intercepters for storm water in excess of that which
can be carried when the flow of sewage is less than the maximum rates
assumed as already described, in other words no special allowance for
storm water was made.

Caution. — The foregoing outline of a rational method of estimating the
quantity of sewage to be provided for applies to the deeign of intercepters
and large trunk sewers and the units adopted are for maximum rates of
flow when the sewers are running full.

AVERAGE RATES OF FLOW

The average rates of flow upon which estimates of cost of pumping and
treatment may be based are much below the maximum rates, and,
from the data available, appear to range in a general way between 100 and
125 gal. per capita per day for the larger cities. For small towns average
rates appear to range from about 25 to 60 gal. per capita per day.

Bases of Design of Existing Intercepters.— The allowances made by
engineers in the design of a number of existing intercepting sewers are
given in Table 54. Some of the older intercepters, designed on a basis
of less than 300 gal. per capita, now appear to be inadequate for the
service they will ultimately be required to render and more recent designs
are more liberal.

iic Hizca of combined sewers and storni-watcT drains are determined
by the raUin of rainfall and the available slopes for the sewers*
recipitfttion and the run-off from areas of different i^hapea,
face cliarttctorLstiot should nevor be neglected by the engi-
' uitcns«t>e<l in sewerage works. Until about 1910 there was a general
ienciency among engineers to rely on \'arious forraulad for run-off^ but
•bout tliat time the belief began to spread through municipal engineering
effiises and among con8ulting specialists that there was great need of more
eomplete and more accurate knowledge of rainfall and nm-off , upon which
to b«*c the calculation of sewer sizes,

M08I precipitation records give only the total amount of rainfall day
day, or at mr^st the total precipitation during each storm, together
rith the time» of beginning and ending. 8ueh records are of iilight value
s Ktudy of jftorm-water run-ofl. It in the maximum rate of precipita-
1 lastang for a suificient time to produce maximum run-olT conditions,
1 11 of im fwrt anc'C. Ratey of precipitation can only be obt ained from
J rooonk of automatic recording rain-gage,s. The use of .such gages ha^
irJierftlly IxHm Hmit^l to the larger cities, including the more important
IhcT Bureau Station** and engineering officers where run-off problems
Ijeen studied in detail, and mitil witliin recent years very little
^istwtirthy information relating to maximum rates of precipitation has
L Available.

itlieN

rbkbi

AUTOMATIC RAIN GAGES

The priiit'ifKiI type}? of automatic rain-gages are the following:

tbtFergusson Gage* — ^This instnmient, Fig. 70, i^ made by the Inter-

•**iojmI I rit Co., CarnVTidge, Mi\ss,, and costs about $80. The

^**^^fi^ 11. and the outeido diameter 18 in., the diameter of the

'^ocUir ring bmng S in. It hiis a total capacity of 6 in. of rain.

»n»*w&t<sr received by the collector is discharged into a can snprM>rtcd

^"pw* ft 0|irtng bahince, the movement of which itt transmitted by hnk

•noving tiu'ough an arc of a circle and making a record

•<*d by ji revolving dnnu. The length of the chart i^i

'^litixig 24 houra of tirne^ and accordingly the time scale

- ^ 'Is 71. The height of the chart is 6 in. and the precipitation

*»n5i5or4(lu. natural scale*

207

PRECIPITATION

209

link motion contains several joints and there is possibility of 'lost motion
and friction in the joints.

Dn^er Gage. — ^The Draper Manufacturing Co., New York City,
makes the recording rain-gage shown in Fig. 72. This gage is 26 X 15
X 10 in. in size, weighs 45 lb. and sells for $75. It is in general similar
to the Fergusson gage. The principal differences are that the gage
has a capacity of but 5 in., instead of 6; the motion of the pen is from
the top of the chart down instead of from the bottom up, and the time
scale is slightly greater (if the clock is adjusted to revolve the drum once
each day). The circumference of the dnrni is about 12 1/2 in. so that 1
hour of time corresponds to a little more than 1/2 in. on the chart. Sub-

FiG. 72. — Draper rain gage.

Btantially the same comments apply to this gage as to the Fergusson
P^ except those relating to the link motion. In the Draper gage, the
•rm carrying the pen is actuated by a fine wire passing over a quadrant
Utttead of by a link motion.

Draper Gage, Old Pattern. — ^In the old pattern of the Draper gage the
water was collected through a funnel placed in the roof of tlic building or
chamber and conveyed through a tube into a tipping bucket susixjnded
from two helicoidal springs. Fig. 73. Those springs were so adjusted
that the scale of precipitation was magnified ton times, that is to say, 1
»n. on the chart represented 0.1 in. of rain. The pon ami was attached
to the bucket and moved directly with it, from the top of tho chart to
the bottom. When 0.5 in. of rain had boon collcctod the bucket dumped
*nd immediately returned to its upright position bringing the pen to zero
at the top of the chart,
u

210

AMERICAN SEWERAGE PRACTICE

The chart, Fig. 74, was cairied
on a flat plate suspended from ti
track and mo%xd by clockwork.
Aa originally construcleti the
chart was made to reprGu^cni 1
week of time, but moreret^ntly
the clockwork has been modified
so that the chiirt makes a com-
plete traverse in 24 hours. It
m, however, so short, the total
length being 12 in., that the
scale is very small, only 1/2 in,
per hour. The price of it was
8175.

By thLs instrument the precip-
itation is unnecessarily ma^ni*
fioii, while the time-scale, as in
the case of most in^ruinents on
the market, is too small for ao-
curate determination of high rates
of rainfall The necessity of

„ -.. f^ . ij . I phcinK the collector upon the

Fio. 7J.— DraixT ram gage, old style. - - ^.i. i i r i

'^ * ' ^ roof of the buildmg, or else ooa-

structing a vault for the recorder, is also objectionable.

A recent improvement of the old type of Draper gage, devisod by

George A. Carpent^jr, city engineer of Pawtucket, R. 1., makes possible

f».AZ£/

CttV OF FAWTXTCICET

CITY ENGINEERS DEPARTMENT

"XZi^

Fio. 74. — Chart from old-etyk Draper gage.

PRECIPITATION

211

¥

thfteiftel determination of 2-minute intervals of time, and accordingly
tbc maximum rates of precipitation for very short periods can bo ac-
> di?terniined. Thi.s result is accomplished by tapping the pen
f of 2 minutes in such a way as to
BUdce ft dot heavier than the line traced by
Ibe pen and therefore readily diBtinguinhable.
^ Tto the amount of preci]>itation in each 2
bo read from the chart with

fmt Ga^e. — This is one of the most
widely u^d autoumtic rain-gages. It is
mack by Julien P, Friez, Baltimore, Md.
The pric^ of the instrument is $53.75 and
d the recorder Sfi5., making a total of
inSJ5» In this instrument, Big. 75, rain
» ooUecied in a funnel 12 in. in diameter
ftml conducted tlirough a tube into a bucket
containiag two compartments. The con-
tWiU of each compartment are equivalent
to 0,01 iji« of rain. The bucket is supported on trunnionH in such a manner
ihat AM 90on as a compartment is filler] it tips and discharges the ac-

Fifi. 75, — FricE tipping
bucket gage.

Fio. 76. — Register for Frie« gage.

tttod rain, pri3scniing the other compartment for filling* Each
the bucket tips it makes an electrical contact and caw^ea a pen to

212

AMERICAN SEWERAGE PRACTICE

record a step upon a chart carried by a revolving cylinder. A sample
chart from this instrument is shown in Fig. 77. It is seen that the cune
traced does not represent directly the progress of the storm, the motion
of the pen being reciprocating, up for 0.05 in. and down for 0.05 in.

The time-scale of this chart is 2-1/2 in. to an hour. The amount of
rainfall is Indicated, not by measurement on the chart, but by counting
the number of steps, or of "flights" of 10 steps each. It is therefore
possible to determine the rates of rainfall from this record with a very
good degree of precision. The possibilities of error are, however, con-
siderable. The Weather Bureau carefully investigated the accurac}'
of the instrument and determined that on account of the appreciable time
required for the bucket to tip, the error due to inflow of water into a
compartment already full before the bucket could tip and present the

teimiffi#?aff^^

:; I

The chart is lOJ inches long.

Fig. 77. — Chart from Fricz gage.

empty compartment is sufficient to produce an error of about 5 per cent,
at times of vcr>' heavy rain. It is found, also, that dirt washed into the
l)uckets from the dust accumuhiting in the gage, affects the character
of the surfaces and the accuracy of the record. The adjustment of the
instrument must be carefully made and its record is absolutely de-
{Hudc^nt ujwn the electrical apparatus working correctly.

A tost of such a page, made by J. H. F. Breed, Chief Engineer of ^^
Commissioners of Sewerage of Louisville, Ky.. showed a total discrepancy
of 17 per cent, in a rainfall amountinK to a total of 1.70 in. withamax*-
nium intensity of 7.t>S in. per hour for 5 minutes and an average intensify
of 1 .()5 in. for (>0 minutes. By ilisoharging water into the gage at various
rati's and nieasurini; the actual accumulation as compared with there-
cnnli (I colliMtion, it was found that the rates of precipitation compute
from the gage record should be increased by about 2 per cent, for eac»^

PRECIPITATION

213

I mh per hour. Thus a record showing precipitation at tlie rate of 5 ia.
j p«r hournhould be corrected by adding 10 per cent,» niakinjc the correc^ted
I rate 5.50 iu. per hour. The test was carried to an ob8er\'od rate of

8.4U in. per hour, the actual rate being 9 JS in. per hour. It has also
' IvTti found that the bucket sometimes 4>tap.s on center, thu;^ failing

to rt^fif^t^T entirely, as a port Inn of the wuhT flows out eaeh side and
I the bucket no longer tips.

Queen Gage. — This instmnient, made Ijy (^iiet'ii-( tray (_<>., Phila-
I lielphm, Pa, , i.^ of the same pattern as the Fnuz tipping bucket gage. It

fli.ia-Iiichafd*^A*'

gage.

Richard **B" gage.

^»M ^omplcti% with regiistcring device, for $10i). The recorder ia

iler tlian timi of tlie Freiz gage ^o that the ttme-scale i» 2 in*

^ f 2-1/2 in. as in the Friez gage, and the movement

11.01 in. of rain ih aUo somewhat le«fl.

ICii^e.— 'I'lim instrument is made by Juhvs Uiehard of Paria

pn the L Jiited Stiites by I>nest IL Du Vivier, New York City,

\m two*pattemf>»f a6 shown by Figs. 78 and 79. Model k

8 J in. in diameter, the total height of the insitrument

mm

214

AMERICAN SEWERAGE PRACTICE

being 67 in. and its width 10,6 in. The selling price in the United
Btates is $78, The rain is accumulated in a reservoir (X)nnected through
a weighing device with a pen recording upon a chart carried by a revolv-
ing cyhnder. The height of the chart is 2.9 in,, which repreeentA 0.4
in. of rain. When this amount lias accumulated the reservoir is emptied
by a siphon started by an electrical apparatu.s, and the pen rcturna to
zero ready to record the next filling of the re8er\'oir. The length of the
chart is 12 in. which may be made to represent either 1 day or 1
week. The latter graduation is absolutely useless for recording maxi-
mum rates of rainfall, an<J even with the former the time .scale would be
but 1/2 in. per hour so that it would lu- impossible to measure slinr t timt-H
with any degree of accuracy.

This in«trujnent is open to the objection that the periled durui^j: \s fii<_h
the receiver is emptying may be considerable and thu>s introduce a

The ehwt ia 12 inchfa long.

Fio. 80. — Chart from a liichard gage.

materia! error. Moreover, the time-scale is very short and the pen
moves in a curved line, both of which are objectionable features.

Model B of the Richard gage contains a tipping bucket so desigtii^d
that it tips gradually with increasing accutuulations of water, and does
not dump until 0.4 in. of rain has accumulated. The motion of tlie
bucket b transmitted through a Hnk to a pen marking, aa in Model A«
upon a chart of the same kind. This instrument haa a colloctor S?. 1 1
in diameter, and the total height of the instrument is 61 in. The i; .
mum width is 13.8 in. It« selling price is $171. The clmrt is tlir ^ain -^ i^^
in Model A, and the time-acale is too small for accurate detei*nuuuUua id
the rate of precipitation. The motion of the pen being in a cun-cd Itne
is also objectionabU^^ and the [>08sU>ility of errors in the transmisaion v^
the movement of the bvjcket to the pen arc considerable, Jt w &Uo
su1)ject in some degroo to the samo posHibilitied of error aa llio Fricit

PRECIPITATION

215

A wiapk record from a Richard gage, used m Philadelpliia, is shown
in Fig. 80.

MttTfio Ga^e. — This is a very elaborate gagy oi liiu weighing type,

Fio. 81. — MarWn gage and roister.

Tb« churt i» 81 ineb«^ lung,

Fio* 82. — Chart from a Mtirvin gage.

drrracd by Prof. C* F. Marvin of the U, S, Weather Bureau^ and con*

] \f^ Julten P. \Y\\it of Baltitnore. It in ast*d at only a few of th»*

i£i<^i (Liiportaot W<iath<»r Uureau stations. It m described in detail in

216

AMERICAN SEWERAGE PRACTICE

CfZ-naer

Circular E, Instrument Room, U. S. Weather Bureau. The precipi-
tation is received and retained in a pan supported on a scale beam.
Fig. 81. Deflection of this beam makes an electrical contact,
causing a record, and also a movement of the counterweight to again
balance the beam. This record is made for each 0.001 in. of rain. The
pen moves back and forth across the record sheet, which is nearly 3-1/2
in. wide, the entire motion in one direction corresponding to 1 in. of rain,
so that the depth collected is magnified nearly 7 times, Fig. 82. The
time-scale, however, is comparatively small, only 1 in. per hour, but
inten-als of time as short as one minute can be determined, so that it is

possible to determine rates of precipi-
tation with a verj' good degree of ac-
curacy.

The receiN-ing part of the instru-
ment is of comparatively small sixe.
Fig. 81, and can be set upon the
ground.

The principal disadvantages of this
gage outside of the very considerable
expense, are the delicate mechanisms
and electrical contacts to be kept in
<N-der. This gage is only made upon
special order.

FitzGerald Gage. — ^This gage was
devised in 1878 by Mr. Desmond
FitiGerald and was described by him
in Engineering AVif«, May 31, 1884.
The rain is collected in a funnel 14.85
in. in diameter, and conducted through
a tube into a receiver containing a float. The diameter oi the receiver
is such that 1 in. of rain cau^^s the float to rise 2 in. The float carries a
pencil bearing directly upon the chart carried by a revolving c>'linder.
This cylinder is of such a size that a chart 24 in. long is revolved once
ever>' d-ty so that the time-scale is 1 in. per hour. It is therefore pos-
sible lO determine rates of precipitation with fair accuracy.

Tliis instrument has never l>een put upon the market, but it has
been used by the Boston and Motrojx>litan Water Works at Chest-
nut Hill Re.<or\oir, and the Engineer Department of the District of
Columbia.*

The principal disiul vantage of this t>-jx^ of cage is that its coUecto'^
must l>o placed u[H>n the roof of a buiUiiuji, or ol<e a chamber partV^r
uiidergrv»und must he oonstructod to contain the receiver and cylind^^-^

* The Builvior* Irvm Foundry, of l>v»\-ivl«rn«v. R 1. j* pr>'(v&nnie deaiflM for « gsf^ q/
the FiuG«r«M type, vhicii il u ex|>ciL*t<Hi mill br «^\1U for about f lUOi

Fig. S3.— FitzGerald gage.

It hBA die gmat advantages that it requires no electrical apparatuis and

I mrrhanic/il motions other tlian the clot'kwork.

[ HeOmanji Gage.^ — This type of recording rain-gage is C4>mmonly used

^l irrrtnsinv and in other parts of Europe, It is similar to the FitzGerald

Hhr pen is carried directly b}^ an ixrxn connected

:. soir, and makes its record upon a revolving cylin-

It dilfers in the small size of the reservoir and drum, the former

r r H^.esisary some apphance for emptying the receiver for compara^

d\ accumulations of water. In this gage a .siphon is provided,

ihiiili tlie rceciver is emptied into a can below, the contents of wliich

vurd Im> nn^ji^tind. Tho chixri record is seriously defective on

■M

Oicx9rom of Maximum RainfaU
at Boston, Mas5.

1B79 - two - leei -mz -leei.

Oejmofid FitiGeraldXE .

The chjirt is 24 inrhea lutig.

FiQ. S4. — Chart frum FitzGerald gage.

its small timo-sealo. This gage has the further objeo-
Stiver min falld wJiile the receiver is being siphoned is not
'•"•I and Bcrious errors may be introduced from this source.

CLOCK MOVEMENTS

m tinportiujeij of a goml clock movement in an automatic rain gago
riMir iilwiiy» njco^iiued. It Im, however, a point that should receive

^^^^j^jgum

218

AMERICAN SEWERAGE PRACTICE

careful consideration in the selection of an instrument. Not only
should the clock be oarefuUy regulated to keep correct time, but it if? of
much importance in any work involving two or more automatic gages,
that the clocks be accurately synchronized, as otherwise it is impossible
to draw any trustworthy conclasiotis relating to travel of storms, or to
the time interval between rainfall and run-off in sewers. It h very
desirable that all clocks be provided with diaU to facilitate regulating
and synchronizing, and in important work of large extent the pructioiir
bihty of electrically controlled clocks sliotild be considered.

SETTING AND EXPOSURE OF GAGES

The correct setting of an automatic rain gage is also of gre^it importance.
The exposure should be such that no objects which might intexfere with
the registration^ l>y causing wind currents or otherwise, are within 50 ft*
of the gage, and the collector ring or opening of the gage should not be
more than 30 in, above the surface of the ground, which is the standard
setting lor the regular Weather Bureau rain-gage. This last condition
is one which it is often difficult to meet. Elevated gages usually show
a considerably less collection than those with standard setting. If it
is inipossil^le to locate an aotonmtie gage substantially at ground level,
a standard rain-gage of the ordinary type should be maintained in the
vicinitj^ of the automatic gage, and the records of the latter should be
adjusted to accord with those of the sttmdard gage. The following para^
graphs from Circular E, Instrument Division of the U. S. Weather
Bureau, entitled ** Measurement of Precipitation/' are pertinent in this
connection:

"Exposure of Gages.^ — The exposure ofgagea is a very important matter.
The wind is the most serious disturbing cause in collecting prtjcipitntion.
In blowing against the gage the eddies of wind formed at it a top and about
the mouth rnrry away rain, and ospednlly snow, so that too little is eiiugjit.
Snow is often blown out cjf a dei*p gage after once lodging tlvereiiK

"Rain-gages in sliglitly different posit ions» if badly exposed, catch very
different amounts of rainftdl. Within a few yards of each other two ga^et
may show a difference of 20 per cent, in the rainfall in a heavy rain stonn*
The stronger the wind the greater the difference is apt to be* In a high
location eddies of wind produced by walls of buildings divert niin that would
otherwise fall in the gage. A gage near the edge of the roof, on the windward
side of a building, shows less rainfall than one in the center of the roof.
The vertical ascending ciwrent along the aide <»f the wall cxtendft slightir
above the level of the roof, and part of the rain is Cfirried aw?*
In the center of a large, flat roof, at least 60 ft sqtiMr^, tin* '
by a gage does not differ materially from th
grounds A gage on a plane with a tight tio;n
a distance of 3 ft. will cuUect i\ per tnitii, more rum

PRECIPITATION

219

J^gjg^the value of the precipitation records depends so greatly upon

Bure, partiriilar care shnulii he takt-n in selecting a place for the

the gage, and every precaution should be taken to protect it

[frotD molc^ation. If possible, a position should be chosen in some open

|lut, imohitlructed by hirgo trees or buildings. Low bushes and fences, or

nlli that break the force of the wind in the vicinity of the gage, are ben^

, i( At a distiince not less than the height of the obicct. The gages

I li«» P3cpo8ed upon the roof of a building only when a better exposure

pt ; and, when so located, the middle portion of a flat, unob-

H Inaed by parapet walls generally gives the best results.

Measurement of Rainfall. — It is generally conceded that

Tof rHinfali is obtained by the so-called pit gage; that is, a

imikcD «u1Iector, with its mouth elevated above the ground only far enough

|l<>pnr\*pnt inaploabing to any serious extent and set in the middle of a large
tipra Ifvel field. Such a gage, however, easily becomes fouled with leaves
«id litter, and t*on»eqitently its use is objectionaljle except as a standard of
Trftififncc in ex^HTimental investigations. A better disposition is secured
i: a shallow pit, a foot or so deep, with the earth thrown up in a
in 6 or 8 ft. in diameter. The collector is placed at the center of
ibc tleprf«ion with its mouth about level with, or a little below the rim of
tbtpit. Such a gage Ls so effectually sheltered from the wim! that it collects
thtftutie quantity of rain as falls upon an equal area of the ground near by.
''Kiphear demonstrated in 1S78 that almost or quite the true catch of rain-
iail cuuki be oollect<^d in ordinary rain-gages by surrounding them with a
*wmf)rt-€hapcd shield of sheet metal terminated in an annvilar rim of copper
WW giuJN*^ 20 gage, mesh S wires per inch, to prevent insplaslung. This
dfviocBo (skt minim ieed the ill etlects of the wind, that one of these shielded
iOQ a pole 18 ft, above the tower of the university and 1 IS ft, above the
ml, collected the siime amount of rainfall a^ a shielded gage on the
, pound. UeUmann and others have also found the Nipher screen useful,
ud luive secured equally satisfactory results by the use of a fence or wind
llinkc flfound the top of the gage, at a distance from it equal to the height
Icrf tlje gftgf*, and at an angidar elevation above the gage of about 20 to 30
Wf ThcjM* tlcviees <leflect and check the force of the wind at the mouth of
1^1* rng^ to such an extent that the raindrops C4in enter the gage in a normal
|numnfT, and a true catch be obtained.

^h •Tf-nis appropriate at this point to say that, while the Weather

'fjiij|x«llpd to expose rain-gages upon the roofs of lofty buildings in

^r tlie cjitch of rainfall thus obtained is often quite siitisfactory.

rW in acconi pi ishi»d by taking advantage of the sheltering and protecting

I hifliittnc** afforded by large parapet walls, which are generally to be found

I ATWHtd flat-topped office buildings. Shields and guards upon the gages

lliwajplvfii in these eases are not so effectual, since the distribution of the

i wrnovor the riKif i^ qnitc irregular* The whole building may be regartied

rain*guge. if shields and fences could be put around the

I tntr ...tch might l»e st'cured, but in the absence of these, a

of the roof, especially if it is surrounded by parapet

1 fa nearly the true amount of rain. Roof exposures

*he Weather Bureau as an unavoidable necessity at ita

m

220

AMERICAN SEWERAGE PRACTICE

stations in the centers of largo cities where better exposures are iinposfiibi
Ground exposures obtain wherever conilitions permit, as for example in th
smaller cities and at stations of ctMjperative and special rainfall observers.

*'From what ha» been stated if appears that the pit-gage is probably tin
ultimate standard for the collection of rainfall and that a nearly true catc
may also be obtained by the use of properly shielded gages.'*

INTENSITY OF PRECIPITATION

It is well known that in a general way the intensity of precipitatiG
varies iuvcr»ely w^tth the duration of the downpoui*, or in other word
that very heavy showers do not laat m long as rains of le-sser intensity.
This variation in intensity, however, wa^ not widely retsognlzed aa
significant until automatic rain gages had been used to a considerable
extent. Until recent years no considerable amount of trust wort I ~
information on intensity^ of precipitation was available, since [iracticaU;
all rainfall records included little more than the totiil precipitation
each storm, or at most the time of beginning and ending of the storni
addition to the ilepth of rain. Moreover, not until the establishment <
automatic or self-recording rain-gages became somewhat general, and
until these had been maintained for a sufficient period to get records of
some length, was there sufficient information on which to predicate
definit-e statements as to the relation between the intensity of
rainfall and the length of the period during which the rain might fall
contiouoasly at any given rate.

Relation between Intensity and Duration of Rain.— One of the earti^
attempts to determine the relation between the intensity and duration (
precipitation wa.s that of Prof. F. E. Nipher of St. Louis, who^ study tol
the records for that city, for a peritHl of 47 years, and analyzing sue
information aa he could find relating to the heavier storms, reiichu
the conclusion that this relation could be shown by the fonuub i — 300 J|
(The American Engineer y May 8, 18S5), where i is the rat nf all
inches per hour and t is the duration of the rainfall in minuteg.

In 1889, Emil Kuichling, investigating the rainfall in tlte vicinity
RocheHter, N* Y., similarly studie4 such records a« were available^
reached the conclusion that in Rochester, for raina lasting loaa ihjm
hour the intensity might be exi)ressed by the formula t = 3.73
0,0506 t, and for perioiU longer than I hour and hss timu 5
the intensity w^oidd be i = OM — 0.002^ To KuichUng*a stndkdi
due, in large raeiisure, the present development of the rational method
estimating stonn-water run-off.

In 1891 I^of* A* N. Talbot analyzed in detail th** minffill r<»c
reported by the United 8tatef« \V leather ]h
sources* The greater "^'^ ^'^ tiioni wnm t< ,

PRECIPITATION

221

I

m

^

" ^

^

n

-

T-

-r

-

^

^

■^

n

n

^

^

"■

^

Re lotion betvwen
Tim* and Intersity of Ra(f>fal|

accord i rig -fo

Talbot's Fof\mulas

FofEaiternaS.
Ctfr¥0 4^ tftrtmf Sfarmi, i* jtjJ
Ct/rviC^ Htavy Storms, i- ^

Form»h» ^9H^d by A. H Talbot, tSU
Pt^itHt ^ffrt% 9rt from TrwfnJmS^cCE,

J

I
_

-

'

ni 1

.

V

II

id

'

I

' ,

\

'j

^

\

\

L

' J

s

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s

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s

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^

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--4

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•».

^

,

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^

— ^

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^

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—

-

=^

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k-

k=

-

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r

-

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-

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—I

~T

' 0 Id 10 50 40 so W 70 80 so tOO flO llO tSO MO f^O 160 170 - tSO i^ 100

nrni<f)tnMinvt«s

Fia. 85. — Talbot's intensity of rainfall curves.

mrm

Relation between
Time ond Intensity of HafnfoW at

Boston, Ma^s,

CwfVf 4, (* ^ (Shtrm^m, ffOQ
CurtfStt'jTXff ** "

10 40 So &o 70 £a % too (10 tZO ISO HO (^ no 170 ISO J90 TOO

T^m^^ffhr^MF^V/t«.

%* — Boston intensity of r^nfall curvet.

^^^^ 222 AMERICAN SEWERAGE PRACTICE ^^^M
^ 1

■ r-

t 'i 1

'.

f ; 1 I

T r ■ r^-'

Mill

:t±3z

1

Relation betw««n
ime ond Intensity of Roinfotl a1

Boston, Mass. -4-

^ 1

B

1

I

I

-

\

\,

i ' I 1

" v

\

^^

J#s

^

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%-

xjl ■

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"*="

"■*

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^^^H

10

ti _

la »

40 50 f>0

70 60 90, 100 110 110 m )40 ISO 160 170 «0 ««
ostou intensity of rainfall curve. ^^

1

r

, Relation bet\

IntensiTv and

!

\

veen

\

Duratiooof Rainfall

Oft Shown by
Pluvromcter Records

PKlLAMlMm, Fa.

Curves Deduced from Records of -
Z5 Years.

A

1,

\

1 \

\ \

m

^ ...

ft -J

5^.

s

. n:-

' (f"- ' "

om «nnuoi rreporr, DuT«avjOT:>arveyfe,i3ii,^ "

N. ^

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10 IQ 30 4a W 60 70 BO 90 100 UO f?o *^ i40 J

1

PRECJPITATIOS

22a

H-.-j-

^

^

^

T

T

l-H

hill

n -^ -L

'

"-iii

■ ■ 1,/ ■ '11

ReMitjn bat ween I

^^ 'IT

Tiin« ttnd Irrtftrtvrtv of Ramfall Ot I I 1

In ^-Z

--

BALTIMORE, MD.

Ll::::

Ci^i^Ai^^

s ^

hk^

_ J

CuntBa' Mr \

i» L V j '

{Cmhif7.W^mfritkmO

? ' I \ !

5 7 T Ti

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fftfnie^h sfyfm 9fMfff^m4 ...

i,_'

f llh^

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(it*f. ACottt, Mtfq a i9U.)

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L

0 10 Z9 30 40 SO eo 70 so 90 100 110 )?o f3o HO ISO leo 170 MO 1^ zoo

Tir»i«(f )in MinutM

Fici. 89. — Baltimore intensity of rainfall curv'OH.

C' 4/* =;i r<i

tfl 4i] --ft ^ - 0 •*» in -n ?."

Fm. 00. Hav.'krihAti rttf-nKity .if rainfall 'nn-'^fl.

^n an "CO

224

SM-R: A\ srx-£SAGE PRACTICE

-

Chicago. Ill

^0 iO 10 ^ -

so 90

Fig. 91. — C'hicazo intensity ...f rainfall cun-e.

TT-

f?-tation between
T-TTiBoni IrrtensH^ of Roinfoi! |-j^
at
LOU1SVILL.1 , KY f^

10 20

r/) Ji3 uO 150 UO ]50 160 170 ^
Time (f^inMinute3.

1m(J. 9U. -liouisvillo intensity of niinfall curves.

ttOt*

^^P tHEVlHTATION 225 ^^H

J but to a few cases the records were those of aelf-recordinp; gaRan maiu* ^^^H
Uiiu^ in Uic larger cities. From this 8tiidy he cod eluded tlmt for that ^^^H
L p*rt o( ;hc United States lying e^t of the Rocky Mountains the formuhi ^^^|
^fti « 300/(1 + 30) \voiil<l express the maximmn rainfall whit'h was ever ^^^|
^ ' ' ►'X'ur, and the formula i = 103 /(^ + 15) would indicate the ^^^|
1 i{ as heavy rains m it would ordinarily be necessarj' to con- ^^^H
r *i«ltiJ jn engineering design, Talbot's studies show very few storma ^^^|
1 iti<UxHi ifiving iuto-nsities higher ttian those shown by the firtjt formula, ^^^|
jl Irtit & coniiiderable Dumber higher than the second equation, ^^^1

-Jl

^^^^^^Hi

' 1

t

I . - , .

-i_

rj -t *-

Re Motion between
Tlm« ond IntetiBity of Ra^nfaU
at

5t. Louis, Mo,

(m m Homer mo)

■ •,. 1) '

, I JX

lei 4-1 [ ,

;" t ^

^ft I

^ t-^

^iXzz

r'tt+ti

^■iSEir

mm

'

■

j

^H$^£

^^Bt^

Hrr

rS '

'

^

p^^^

k

k*^

■

^

-

-:

«

1 *

-^

=

~

^m.

--ij

p^

^..

-

—

-

-H

-

0 iTl L^'i J \"\ n rr^

■^

'

"^

— !

—"

'

E t

—3

—

~

—

-^

=■

"

IP 1 la f

0 }0 49 do 60 70 80 90 100 110 1
Time <fJ>nMlnyT«9^

Vui. 93. — St, LfHiis ifiifKrtifv ui

Iv, with the uicrca^viag imi ol

r use of the rational method <

record-* of automatic rain-gagea i

separately analyzed in detail, and

c been uned aw a basLs of design i

S5 to 97, incluaive, have b

1 curve?*.

is, Mo.— Fig, 93 shows the rain

^^ " ^' ' i^tant Enginf^er

•■' ^ upon which i

«J i» thus dci

CO t&O 140 150 [60 170 «0 IfO I

rainfall curv^e.

^ automatic rain-gages, an<
jf de-Hign among t^ewer engi
n the more important citie
cun^es have been prep)are<
n those cities. The curve
eeh selected as typical ex

fall curve derived for St

in charge of Sew^er Design

t is based. The method h]

jcribed by Mr. Horner i]

^^^P

^^H
^^^H

^^1

^^^H

^^^1

^^^H

^^^H

226

ANfERlCAN SEWERAGE PHACTWE

"In Fig. 94 are shown the Wc»ftther Bureau llo<H)rd8 of ejxwssive rain^i
in St. Liiub* The abscisiias arc the ytmrs uf occunrrrcp and Ih*? ordi-
niit»*8 HH? the rates of rainfall. Each point represents a rain; those? poirita in
which small arrows are shown indicate that the value was deriv^etl fn>m J*
rain of slightly greater duration, and that the rate shown is therefor© in
error by a small amount. From these graphs, values were chosen for the

15

to

-

n

~ ~

T"

■"

T

"

AC

.

1

n

#r

«{

■'FTl

A

Eiict9»Ive Rote* for 2- Hour Ptriod

'ii"

9

1

',

w

J.

H

(V

E^ncc&atvc Rates for l-Hour i

. - <

^n-«,!

> H

rA

i

C

2

t

1

1

II

1"

1

Ejtcesitve Rot«a for 30- Mir

j-r

cciod

-» ^

-*SS

? A

1

m H

t\

'*

I

r 1

»

0 '

^ 0

E)t«4*<vc Rate» for 15-Minutt Period

^

'

^fi

3_

c

■

■ H

M

"

^

"::

-F

t-4^

: n

A

1

^ _i-j^

•

T 1

:

"

Excessive Rat»i for lO-MmutePtenod
.............. ■ . .

r '"

■

0

ft

ig.

<

*

1

I

yP

|L

1 1

T '

1 ■

,

^'

1

Ejicetsive f?atr»^r 5- Minute Ptriod*

^

r r I

■^

•

1 4
■ a

» «

■ i

■ *

- 1
1 1

1 <

B 4

;:

Si

\ <

t ■>

1 1

:!

> 4

l\

U:

1 «« 1

Ss

isi

< 1 i

Year of Occurrenct.
Fio. 04, — Rates of rainfall at St. hnum for dlffrrrcnt pcrioda.

W. W. Harnt<r, Enatn'^

rainfail rate which excluded storms oecurrujg ji^ u/t i^ti^r ioUTVals than nhaut
15 years. The values of i* were plotted on logMi^Hrr fr puiwr wUh thoaa

for /, I 4- 5 and t -j- 1(1 ^ the second viihc giving dc^*
tttnj?ent of 0.85. The resulting fonnula, i - JSiV
awkward form^ but fits the values chosen so closely i

Tht* j)lotted .vtoruiH show uo warrant for tho curve, % >
NiphtT ill 1.S85*

-ht hn**, with «

l;.*wi rather an

It wa» rotamcd/'

m,t, by Pn^

PRECIPITATION

227

Spokane, Wash-— R. A. Brackenburj^ in Eng. Record, Aug. 10, 1912,
gh'cu^ the formula

2^ Q2

•■ = itI:i5 + «-^^^

which WHS used in the design of a large storm-water sewer for Spokane.
A cornparit*on of the several curves shown above is given in tahulrtr
form in Table 69, whii-h ulso includes the general cun-e i = 32/("'*
SDi^estod by Charles E. Gregoryi and the four general formulas

I =

12

15

F<Mtn <rf Rainfall Curve. — In many cases where mathematical express
have been obtained for the rainfall cun'e, they have been wTitten in

w*

1 'I'll

" " n "" "T"

' '' T

] T i . .- - — -

a

r-

.L

^ 1

\

1 \ ~^

•

r i \ \ \

12

Relation between , ^ ^
at

NEW Orleans, la,

Ofrvw i' -^ {Mtftalf&tddy, fSff.)

^ H^pmtnf ObierYOiiotii bfStmnmi mifrBoattl

m4- tsto.

^11

i 1

r"

to

*

!•

*

ce •

i

fWf

Y~

1

r

V 4 -"» 1-1

i

2.*^

14^^

l^

J.l^

Ml

I

1

\.

*

f *

'Sr

K

hs

^

p ** .■ ^

^ ' " 'V

^ T

1

, M 1

A

'n~i 1 TTi

____~___"x_ _:

0 »o ^o so 40 »o fio 7d eo 9« loo 4|o izo iM> i^o isg i«9 i70 i»o m 2oe

Time (f^ »n Hint/t«t.

Fi ^ 95»— Xew Orle&nK intcniiity of rainfall curve?.

%\\v fr-nri 1 ^ ' < -f ^). This formula has the advantage of being easily
^jIvaI*!*' hy Mfr,pU« flrithmi^tWiil operations; and if tho. comttanlA in it
hu\ e li€i*ij L-r L it usually ex ' ol>{ion*a-

tion« with a I... -., . -.> ,: iicy between u .. mitea and

2 iMiijri' duration of raio. For either greater or leaa periodic of time,
howeror, the result** obtained from this form of curve are geinerally too

1^

^tfi

228

14

AMERICAN SEWERAGE PRACTICE

15

i

S-io

I'

eft

V

h

I.

*-
'5

*-
c

' z
1
0

T

~

~

~

-^

"

r^

^

^

~~

^

^

~^

n

^

"

TP"

^

~

,

1 1 1

^l|- -r r ■ T T « ' I T T 1 T 1 f T 1 ? 1 1 1

R«latJon betvveeri
- Time and Intensity of Ffafnfon

at ;

-^

H

DENVr

in^ w»L

ORAUP.

u

'

JU

as- d

LL d

I*

A.i_i

i,WHV»fBW(7ri«Tiur/r9tfrv/; #?//,

T H

u\ - 1

1

l^?

\r-V '-

\ VZj

^

n

f^

^

^

s

"S^

1

-ih -^

s

^

'^

•^

1 1

u

-A

-

H

^

P

i

^

q

-^

^

—

-

—

^

—

-

—

^

^

^

-

j 1

~~

—

J

~

Zl

>-^

-J

J

^

~

::=

»

"•

hB

■"

"

'^

"

"'

"+ti

0 )0 20 30 40 $0 60 70 60 90 lOQ IkO leO |30 (40 ISO t60 i70 «80 ISO 100
Time (r; in Minut«a.
Fia. 96,— Denver inienstty of rainfall curves.

M

It.
I'

§7

I'

^

— 1

^

T--

^

1

T

■

±^

;' Hela+ion between

Tinw and tnHnsity of Rainfall

SANFRANCtSCD. CaL*

""

♦ " - ^ " ' - $^,%Jfi.

■*

I

\

1

\

^

^ s

^\^^

t; ^

■*H

^

S=

P-

^

—

»

^

-

—

^

—

^

-

-

_

--

^

~

~

~

^

'^

-r

■*•

'-

^

~

s

^

H5

!8

■

-

:£

-

a

0 10 20 50 40 60 M 70 90 90 100 tJO IZO HO l« IM |^ 179 HO 190 M
T\me(t)in Minute*.

FiG- J*7. — San Francisco b tensity of rainfnll curvng* ^

^tiMm

pefcipita t:os

-■v-Ki

-: ^ ~ '

■ ■ ^ — ■ ■ - ■ —

-. — » —

: ■■ fc * » »

230

AMERICAN SEWERAGE PRACTICE

Si

I- .

d I® i"*
■3 — I c

S o 1 *=■

o .

^2

1

i

0

1

•« -t c« ^

s ^ ^ ^

_d

8

r-

_5=5 0 5? i. ^ — o

_c _ cs o -* — — =:

S 1^ ^ o m <o

o — >c -♦ ^* — o

«9 -^ e^ « o «i rsi"

ae ■^ s! ■*• ■* 's 3Q

*;* « « « ffi ^ d

eg d

S 5: 2

8

_-*'_ ci -^ •>> -^ *n —

3 s ^ gs s

S S; S

S S ^

_W _e« _f«

sr s; 8"

HS3S^^ ;5

?i

3^00 0

00

s

ssssss?

^Jl

— -*oo 0

00

°v

i5J2§S$

^^

afl

--P© ©

0©

0 .

SSJSgS

s;;

ft

*-r4wo 0

0©

d

SI 2

gpcsi^ O do »* I

r-

SI

w

^

rt

W

vnrc «» ^c>4 to

«

'^

w

«

rt

t<9^nE4 0

«^

- I

8

S

9

oS^gSl^g

S

s

3g

«

8

SS^5IS

^^

^ 1

(if

w

u

V*

e*

«

«M^O-*«N »--

^
S

^«_

■«<»

«

^

rs^-*^ -•

^^

«• }

g

ff

s

8

Slig:?^.^^

3

a

SS3S8«

32

£1

et

*

3

"8^

8

r* .« -r gc »i^ CI aC

8^Sg33 8

8

«

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-i-

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to

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« « S S ^-5fc *^

I i

e

.a
t

a n

O O

i

i

li

^ 1 1

t4 M u;

k ^ h

3 ^^iSffl ^ «* i! ft * e

W SS.-S — ^-p H3 •§ -a ♦§

« « b J

« fe 3 ** 5 «> g
SSaSo Sea

IX'^'Z iX li l3«*ojot-««» i« li^ iZ 1;! IZ
I I I I I I I I I I I I I I I I I

- '- '^ '- ^-22SS 5 ^

+ :2«>

: ^ i •«* -

<j-s5liX *+ *!

II 1 1 I 1 1 I

I

8 { I fai^i"}:

S ^ S i:^"^ "

I

£j :::ast,t.c* ca

e 4

o o

g = I >5f^ 2 I

S % ^ 3ki^^ "^
j di S >JXj£C eg j

idiiai

Mi

PRECIPITATION 231

low. Practically, this is usually of little moment, since it is rarely
necessary to consider a shorter period of time than 10 minutes or a
greater one than 2 hours in the design of sewers. It is, however, desir-
able, if the curve is to be expressed in mathematical form, to have this
form as nearly correct as possible, and the exponential form, i = o IV> has
been found to fit the recorded observations with a good degree of accu-
racy in many cases. The exponent h is usually found to be between 0.5
and 0.7. When it is just 0.5, this equation can be solved as easily as the
former one, since the results can be obtained directly with a single setting
of the slide rule for each value of 6.^

The form i = al\/(t + 6) is also a convenient one for use, as it can
be solved nearly as easily as the equation jast mentioned, and at least
in some cases it fits the observed points more satisfactorily. It has
the further advantage that the value of i as it approaches zero is a finite
quantity, its magnitude depending on the values chasen for a and 6.

The best practice, however, is probably that of using directly a curve
of rainfall plotted from the actual records, without attempting to express
it in mathematical language. The intensity' to be expected for any given
duration would then be taken directly from the curve, instead of being
obtained by solving some equation. There is no apparent reason why
the relation between the intensity and duration should follow any mathe-
matical law.

When rainfall records from which to construct a curve are not to be
had, it is believed that for the portion of the United States lying east of
the Mississippi River, the formula i — a jt^'^ may be used as a reasonable
basis of de.sign, with values of a ranging from 15 to 10, depending upon
local conditions and upon the extent to which occasional surcharging or
flooding of the works under consideration may be allowed. For con-
ditions similar to those existing in New England and New York, it Ls
believed that in general the formula i = 12/^^"'^ will indicate intensities
that are not likely to be exceeded oftener than about once in 10 years.

FREQUENCY OF HEAVY STORMS

It is of much importance to have at least an approximate knowledge of
how often storms of high intensities are likely to occur. Where the rain-
fall record covers a considerable j)eriod of time it is possible to compile
such information with a good degree of accuracy. The method of work-
ing up the records and expressing the results in graphical form is illus-
trated in the following examj)le.

A record of the storms of high intensity at Boston, for the 26 years

* Set the runner at the value of a on the lower soalo of the rule; move the slide until the
▼alue ot t on the upper scale of the dlide is opputtite the runner; tiuii i on the lower
»cale opposite the enS of the slide.

232

AMERICAN SEWERAGE PRACTICE

Table 70. — Probability op the Occurrence in any Year of Stormb
OF an Intensity of 1 inch per Hour or Greater, for Various Periods
OF Time, at Boston, Mass.

(Bused upon the records of the recording rain gage at Chostnut Hill Resenroir, Boston,
for 26 years, 1879-1904 inclusive.)

Duration,
minutes

Number of storms of

1 in. intensity or

greater

Total number of storms of

tion of 1 in. or greater
intensity

Corresponding number

of storms per year.

• - probability

2

1

72

2.78

3

4

71

2.74

4

1

67

2.68

5

4

66

2.54

G

4

62

2.39

7

5

68

2.24

8

3

53

2.04

9

2

50

1.92

10

1

48

1.85

11

4

47

1.81

12

2

43

1.65

13

2

41

1.58

15

9

39

1.50

17

2

30

1.15

18

1

28

1.08

20

2

27

1.04

22

1

25

0.96

25

3

24

0.92

28

1

21

0.81

30

5

20

0.77

35

2

15

0.58

40

1

13

0.50

45

2

12

0.46

50

1

10

0.39

00

3

9

0.35

65

1

6.

0.23

68

1

5

0.19

70

1

4

0.15

85

1

3

0.12

130

1

2

0.08

180

1

1

0.04

72

PRECIPITATION

233

187^1904 inclusive, is contained in Trans. Am. Soc. C. E., vol. liv, pp.
174-176. From this record Table 70 has been prepared, giving the
number of storms of 1 in. or greater intensity, the number of such storms
of designated durations and the corresponding number of storms of each
duration per year. By plotting the points obtained from each such
tabulation, a series of curves is obtained, shown by the diagram,
Fig. 98.

For practical use, it is generally more helpful to know the curve of
intensity of precipitation in storms of various degrees of 'frequency.
From Fig. 98 it is seen that for a storm of a frequency of unity, or such
as is likely to occur once each year, an intensity of 2.5 corresponds to a
duration of 2 minutes; an intensity of 2 to a duration of 7 minutes; and
80 on. A series of curves of intensity corresponding to different degrees
of frequency or probability can readily be constructed in this way.
Such curves for Boston are shown in Fig. 99, together with three curves
represented by some of the formulas which have been proposed.

Table 71. — Phenomenal Rainfalls in New York City, 1913

Date

Plftce_
^minutes |

2

4
5
7

10

15

19

30

37

49

59

60

85
100
120
123

July 10

July 28

100 Broadway j Central Park

Sept. 6

Central Pork

Oct. 1

Richmond

Intensity i-inchea per hour

8.40

8.10

6.45

9.88

6.12

7.20

6.24

7.56
6.62

5.76
4.80

6.90
6.36

5.64
5.16
5.05

4.18

2.96

5.24

4.84

4.75

4.44

2.30

2.73

3.31

3.80

3.37

1.28

1.56

•i:85"

3.0()

vr

15.00
10.60
7.50
6.72
5.68
4.75
3.88
3.45
2.74
2.47
2.15
1.95
1.94
1.63
1.46
1.37
1.35

From this diagram it is apparent that the curve of extreme storms is
governed by some very abnormal cases. The curv-e C, represented by
the equation i « 15.5 /(*^*, may doubtless be taken to represent storms
occurring not oftener than once in twenty years, and should be a safe
basis of design for even most important structures. The curves A and
^, represented by the equations t= 120/(^+20) (proposed by Kuichling
in 1905) and t — 105 /(( + 20), respectively, correspond reasonably well

234 AMERICAN SEWERAGE PRACTICE

with the intensity curves of storms to be expected once in 15 and once in
10 years, respectively, as do also the cur\'cs i = 12/^*^ and i = 10 /£***•
respectively, and should be appropriate bases of design for the less impor-
tant structures such, perhaps, as the branches of a drainage system.

Similar curves of rainfall intensity and frequency for the City of
New York have appeared as this book is passing through the press
in the 1913 progress report of the Committee on Rainfall and Run-off
of the Society of Municipal Engineers of the City of New York.
Intensity curves are given for several localities. The frequency
curves are based upon the 45-year record of the recording rain-gage
in Central Park.

Phenomenal Rainstorms. — Storms of extreme intensity, commonly
called " cloud-bursts,'' are occasionally experienced in the Eastern United
States. They are usually of so rare occurrence as to be classed as
"Acts of God," for which it would not be reasonable to provide in
designing storm sewers.

During 1913 New York City experienced four storms, in all of which
the intensity of precipitation, practically throughout the storm, was
greater than that given by the equation i = 15/^*^. The significant
facts relative to these storms and intensities obtained by this formula
are contained in Table 71.

These were all storms of remarkable intensity. The maximum rates at-
tained may be expressedapproximately by the formula i = 35 /VO + 7).
These rates approximate those given by Talbot's "maximum" curve
for the shorter periods, but exceed them materially for longer periods
of time.

CHAPTER VII

FORMtTLAS FOR ESTIMATING STORM-WATER FLOW

In the earlier plans for cirains and channels to cany away the water of
I 4om»!«, (snginecrs ba^ed their designs largely upon their observ^ations of
tbe volumes of water seen coming from known areas in times of storm
Aad upon the sizes of natural gutters or water-courses with whk'h they
wert* more or less familiar. Later the tributary areas, whicb could be
iccurately measured, were introduced as constants, and the estimates of
nin-<iff were based upon a given depth of precipit^ition over the whole
di^rict; but with further study it developed that there is a gradual
mluction in the immediate run-off per acre with an increase in the extent
of llic area, and at^cordingly fonnulas were devised by which this fact
WW taken into account more or lesfl empirically. Still more recently it
kau been recognized that differences in the rainfidl, and especially in the
intcanity of tlie precipitation, had a direct influence upon the resulting
«^orm*^'ater flow, and other factors have been introduced into the for-
fliuliifl to tidtc account of thin and of the dope and dinientiious of tlie
*fa^iniigc area. The result has been the gradual development of a
ii«mWr of empirical formulas or diagrams, by which the greatest quan-
tity ' water to be discharged from any given drainage area could

EMPIRICAL FORMULAS

The bc0t known of these empirical formulas, reduced to a uniform
I notatioa, and with the introduction of a term expressing rate of rainfall
|(vbicli WIU5 not originally uned in all of them), are as fuUows:

H f.ondon, 1857): Q = ACii/iS/Ai), in which C = OJ and

ft ^ , nat Q - SXmUs/SIA (since s = *S/10OO).

BttrkU-SSiiJgler (Zurich, 1880): Q « ACiy/iS/A), in which C = 0.7
t» 09, and i = I to 3.

Aikm* (Brooklyn, 1880): Q « ACi\/{S/AH^),in which C = L837
tmdi ^ I,

>icMiith (St. Louw, 1887): Q - ACi\/iSIA), in which C - 0.76
«od I » 2,75.
Ucring (New York, 1880) Q - Ca••"5'»•'^ or

Q = AciViS^ "/.4) = CiA^^^'S^"

^in which Ci varies from L02 to 1.64. These two formulas give con-
iibly different rt^ult^.

235

236

AMERICAN SEWERAGE PRACTICE

Paruiley (Cleveland, 1898) Q = ACi^S^^IA), in which C m bctwe

0 and 1, and i = 4.*
Gregory (New York, 1907) Q = ACi S^^'^^ /A^^'\ in which Ci - 2.S f^

impervious surfaces.
Where Q = the maximum discharge of sewer in cubic feet per second, ]
i ^ maximum rate of rainfall in inches per hour (which is alnic
the same as the quantity of precipitation in cubic feet per
second per acre),'

10 ?0 30 40 50 so 70 50 90 tOO HO RO V50 140 ISO IbO 170 XtO (30 7C0
ValufiS of Q • Cu,"ft: per sec*

(?* Cv>ft. p§r sec, Reach/nq 5mfif€rs. i * Ham faff in cu. ftperiec^pm- Atrm

A • Orainaqt Ama *n Ares. Pracficaffy • tnchpvHottr

C* Constant ^* ^fope ( Feet per fOOO}

Fig. 100. — Comparison of run-off formulas fc»r shipr^ -"^ "<' H^ *'*■*•• f"
feet, and aniaU area*.

A = extent of drainage area in acrc«,
B = average slofjc of the surface of thu ground, in fe
thousand.

Comparisons of these formula« are shown in Figs. 100 to 103 inclusiTfl
and in Table 72, The diagrams illustrate the comparisons for slopos
of 4, 10 and 50 ft. per 1000 ft., and the tabulation eoversi thene siilop«s
and also 250 ft* i^er 1000 ft. It will be ai*en tiuit a very wide rangt) of
results may be obtained, depending upon the formula cho«en»

* Pnrmltry Ukaa i at TDfirf^fttitiiia tbn lnt«iuiiiy of relofatl for « p«rfod of 8 or 10 1

Niid for th« Walworth 8*'»^r ^Ct- ^1 { • 4 in aitl^r i^ proviilr for lit* niort iriffl

•toriiui* Kfiil ftUo fur the rurtUit l««h1 by thi* {»rav»iUnK «iirvctioji ul Um i

FORMULAS FOR ESTIMATING STORM-WATER FLOW 237

I « ffl rt « a" QO -^^ W

-J ^ M M M -^

"LIE

I

IS
s I

1

is

I-

' -^ V « '^ c *P « d

I

P4 ^ ^ « e^

g|l sssaTsTs

IQ i g r^ (S PI Pf ^ « O ©

;igisigii

» « n CO 9t ^

Ifj

i

£c is Sf « K n

s

*

UiS ^ C4 ig 3B R

00

74 m ^ ^ iP4 04 «

I 1

X'

© F** f^ . - *

■ ^ " I ^ I I

"^ Bf ^ ^ .^ tl LS

>^ ± O ^ < H - '-'

3 8

I

r

- I

b!i

bill-

V s *<! (» 1

I <e U3 gs.

< 113 ^ CS

: *^ *^ "!

i o « 1^ ■

! *! * ^ '

' d d e !

* » MS 3C

h* l^ e PJ
P5 rl -^ C

1

12

i

£3

g

SI

n

en

n

9

P5

pa

^

M

a

s

«

^

^

e^

w

N

—

-

s"

"2

i

i

S

il

9C

e

o

o

o

o_

_g_

_«

S

i

g

1

e

-^

s

s

^

iS

e

i « « c -^

I O — rt O
I CM ^ ^ »-»

— el

. »- e ^ 't in « fi e-

i.

!»^

coo

c Q dv

e io -^^ f^'
d Q d d

;^^^SI$S:

o

d

^ N ts J^

<f» <« ^ N

d

d d d d

c

I =1

* I ft F

t, t^ — J w ^

J5:6 !^ ^^

■* a "O J; ^ V
S CQ < ^ IS X

i I

So

AMERICAN SEWERAGE PRACTICE

The first four of these run-off formulas were aaalyaced and comp
by Etnil KuicWing in an atldress before the CoUog© of Civil Engim*tfno
of Cornell Univereity, (Trnns. Assoc. Civ. Engs, Cornell ruiv,, 1893^
This analysis is reproduced herewith, slightly condensed.

Hawkslej's Formula.^ — This appears to have been establish e<i at

time between 1853 Mnd 1850, to express ftnalytically the relation bc^tint
the diameter and alope of a circular outlet sewer and the ningnitude of iU
drainage area, whicli is embodied in a tabic (Table 1) prejiarrd in 1852 hj|
John lioe, Surveyor of the llolborn and Finsbuo" sew^em ^London), afw

500

1000

1500 2000 tSOO 3000 3500
Values of Q - CuJt, periec-

4000

4SM

A - Dnrmage Amr in Ac/9^. PtacPcalty - Irtchp^Hoon

Fia, 101. — Compariaon uf run-off fornniln^ for slope, •?, of 10 feet in 1|G
feet and large areaa.

numerous observations of their storm discharge. As rains yielding rttorr tb *
1 in. in depth per hour are of comptiratively rare oceturence in I^oaiU
an intensity of 1 in. per hour was then probably regarded as a majdii*imi
which provision should be made in mtmicipal sewerage work, and the iliiu*^
ters, grades and areas given by lioe were considered as ttpph*.u*blc tu '
intensity. In its original form, Hawksley's formula ia (aee lietporl
Commission of Metropolitan Drainage, London, 1857):

, , 3 log^ ^logiV-haS
logd^ ,0 —

i^ORMVLASi FOR EST! MAT! NO STORM-WATER FLOW 239

' li » dlani^C^r in inches of a circular sewer adapted to cany off the
storm water due to a rainfall of 1 in. per hour;

A = mi^fnitiKle of the drainage area in acres;

N « limgth in feet in which the sewer falls 1 ft- If we replace N
by its equivalent (l/«), where it denot.«.s the sine of the slope
erf the «ewer« and then divest the above expression of lis loga-
ritlimic forai, there follows:

^00 tOQO 1500 2000 £500 9000 ^SOO
Value* of Q — Cu.ft.pertec.

4000

4500 5000

w * Cfj. ffiptr^^ H^achingSfwtn* i • Rain fottm cu. ft p^rsitcp^r 4cr»

'<• Dm*nagt Arta m Auws,
C* Conttont

S ■ 3fep9 ff*erpfr/000)

I ¥ui. Hrj— (_*oniprtri8on of run-<j>ff forinulaa for slope, S^ of 50 feet in 1,000

feet.

I if tim rtiamcter is cxpnisstsd tn feet D, liiatcad of in inches d, we will have

/>--aooaioi9|* = ^^/J!^

Itmittt b*> rrmemhrjrcd that A her*" reprt«ent3 essontiidly a eertiiin v*olume

rot ir»t«f i|.Hr}.rirtr,'j iji a cf»rtain pcrtoil of time hy the acwer, and that auch

f Wunjc i,, t per KCL'und in equal to the number of acres in the drain-

' ' . M'n MH' i-ntirc precipitatJon, nt the rate or int<nisiiy of 1 in. per

o(T fniiit the 8urfui^* and roaches tlu3 sewer a» fast a^s it falls; alao

umi u yic fomtuln eon tern pin t4"4 the discharge of only some fraction of this

240

AMERICAN SEWERAGE PRACTICE

precipitation, such fraction has presumably been introduoed into the ooo-
stant coefiici('nt. Accordingly, if the intensity i of the rainfall is to be intro-
duced into the formula, the factor A should be replaced therein by the product
Aif which represents the rainfall upon the area in cubic feet per second,
thus giving:

AH*

D>» = 0.0001019

But from the fundamental formula for the flow of water in circular conduits

7flOO

S500 6000 65 W

500 tOOO 1500 2000 2500 3000 3500 4000 4500 ^

Values of Q- Cu.fr. pcrscc.

Q' Cu ^ per sec Reaching 5€wen. i - Rainfali mcu.'ftptrstcptr Acn

A = Drainage Area m Acres. Practically - InchptrHovr.

C = Constant ^ ' ^'op* (reaper 1000)

Vu\. \iY^. — Comparison of runofT formulas for slope, <S, of 4 feet in 1,000 feet.

ninninK full (Ihc Chczy formula, with r = 1(K)) we have the velocity in
feet per st'cond, /• ^ 1(M)\ /).s 4 =^ r)()\/>.s, aud the discharge in cubic feet
per socond: Q = ttD'-v^'A, wlirnco Q = \V^.2'7\l)% and

\:m).2iI s \:i[i:27/ s*

FORMULAS FOR ESTIMATING STORM-WATER FLOW 241

The foregoing two values of D must, however, be equal to each other,
whenoe

aad

GO \*l AH*

9.27/ 8* 8

Q = 3.d46Ai^

which is the Hawksley formula.

Bfirkli-Ziegler'8 Formula. — In his paper on ''The Greatest Discharge of
Municipal Sewers" (Grosste Abflussmengen in Stadtischen Abzugskanale,"
Zurich, 1880), BQrkli-Ziegler gives the following formula, which is based
on Hawksley 's expression :

q^cr^ys7A

where q = volume of storm water (liters) reaching the sewer per second

from each hectare of the surface drained;
c = empirical coefficient varying with the character of the surface;
r = average rainfall in liters per hectare and per second, diu-ing the

period of heaviest fall;
S a general grade or fall of the area per thousand;
A » magnitude of drainage area in hectares.

FVom the data available, the computed values of c ranged from 0.25 for
suburban districts, to 0.60 for thickly populated urban districts, with an
•verage value of c = 0.50; and for r it is recommended to take values
'Mging from 125 to 200 liters per hectare per second. Since 1 liter per
^Mctare per second is equivalent to 0.0143 cu. ft. per acre per second, it will
^ aeen that these values correspond to 1.79 and 2.86 cu. ft. per acre per
■wond, or to rain intensities of from 1.79 to 2.86 in. per hour. If we take
the volumes q and r in cubic feet per acre per second, the area A in acres, and
introduce the sine of the general slope « in place of the grade per thousand
^, we will have; S = 1000 «, and

q ^crVT/A

where the value of c will range from 1.76 to 4.22, with an average value of
^•52; and if we further substitute the total discharge Q for the discharge per
*<^ 9, and replace r by its equivalent intensity of rainfall i in inches per
^, there follows; Q ^ Aq and

Q - cAi\^8/A) = ACi^{S/A)
*« Riven above.

Adtms* Formula. — The formula of Coi. J. W. Adams is developed in his
^Jt on "Sewers and Drains for Populous Districts" (New York, 1880),
^01 the fundamental expression for the diameter of a circular conduit
'^^ing full, viz.:

^ \ 39.27/ 8 1542

1542«
16

miCAN SEWERAGE^

by arbitrarily changing the exponent of D from 5 to 6, and then nuS^hutm^
A /2 for Q on the assumption that one-half of a precipitation « = 1 in
per hour vnll reach the sewer during this period of time, thus giving:

/?* =

ThiB change in the exponent of D was made for the purpose of getting a
larger value for the run -off Q.

For any other value of i than i = 1, we would have to substitute Ai/2
for Q thus obtaining;

D

But for the flow in the conduit we alao have

And as the two values of D must be equal, there follows

g/A*P ^ hi Q^
\61tJ8^ \1542»

whence

0 = l.025Ai\

as above.

McMath's Formula.— The formula of H, E. McMath of St, Louis, Mo.,
was pubhshed in 1887 by its author in Trans. Am, Soc. C. E., Vol, XVlj j}.
183. lU original form is the same as given above, extept that for « the fall
S in feet per thousand was used. It seems to have been derived from a
number of observations of depth of flow in a variety of sewers of known site
and grade draining areas of known magnitude, but apparently without
exact knowledge of the maximum intensity of the rainfall which produced
the computed discharge, or of the proportion of water reaching the 8ewi*r8
at the j)erifxl of maximum flow. The discharges were plotted on a diagmm
as onlinates to the corresponding valuer of the drainage area as nbseisaaat
whereupon the enveloping eurve of the points thus obtained was drawn niKi
its equation sought. This equation appears to have the form of

and by introducing the average surface grade, the rate of precipitation in
cubic feet per acre per second (or the rainfall intensity in inches per bour)»
and the proportion e of water Sowing off from the surface, as factors rnakiaf
up the coefficient 6, we may write:

Q - eiViSA'i = vA>\/<S/A)

For the city of St. Louis, McMath adoptiuJ ft>r ih«-^ miton*. tht? vain
t - 0.75, i - 2,75. and S - 15, If, howevc i

^UMULAS FOR ESTIMATING STORM-WATER FLOW 243

^1 ";w> («) into the expressioa instead of the gmde or fall in feet
e must substitute for ^ ita value, S * lOOCfe; and by placing
' 'V UMju there follows:

Q = CAiVWAJ

9 • 0.75, the yaliid of C will become 2.986, which is preaumiibly
Me to first cIass urban districts j but for suburban districts the pro-
I c of the rainfaU which reaches the sewers is manifestly smaller, and
fiwy be tuJcen at about e = 0.31, thus j^iving C =» 1.234.

It mn*' Vio of intere^ to ascertain which one of the various indexes of the

If A) in the above formulas is probably the most correct from a

! j>oint of view. For this purpose, let u& consider the motion of a

mileriAl point in sliding down an inclined plane or line whose length is I and

I juigln o! indination a. Neglecting frictional resistances, the time ( required

[ fof such a point to traverse the length I by the action of gravity alone will be,

' ■ 's/{'2l/g sin a), where g denotes th^ acceleration of gravity. If we now

fRgipl the length / as the path traveled by a particle of water in its passage

fttitn the margin of the drainage area through the gutters or smaller sewers

[itt th© point of observation in the outlet sewer, then for diiTerent values of

lie slope a, the time t will vary with \/L For similar areas A^

_f^the length / will vary with %/-•!; hence the time t will vary with

vA; m<l if it be further assumed that this time t is proportional to the re-
lUrtUtioii of the discharge, or to llie ratio of the sewer discharge Q to the
[ ^pecrpitnlioii in cubic feet per second R upon the area j4, there follows:

Q/R ^ m/l = ni/A

.ire empirical coefficients.

, therefore, the fourth root of the factor l/A is the most
one to use in formulas of the class above described; and where
iionn from this rule have been made, in order to accommodate the
^m of Q to certain observations or measurements, it is fair to conclude
ihftt the fonnula cannot be of general applicability.

^«nag Formula (New York Diagrams.) — Diagrams of run-ofiF to be

I in New York City were prepared in 1889 by Rudolph Hering in

I with an unpublished report. In the report of the Baltimore

f Commission, 1897, he and Samuel M. Gray give as a formula

from these diagrams: Q = Ci*A"***5®*", and this formula is

Tquoted m Ugdcn's ''Sower Design,*'

Fn»m the Kttttie diagrams, Charles E. Gregory In 1907 (Trans. Am,
f^ K., Yul 5.^, p. 458) with Hcring'S report of 1889 before him,
1 the formula as

Q - CiA^'^^'S^*^^

wb focmB of thit* formula arc somewhat widely known. As is

Umu L r -^ H»oto 103 inclusive, the differences in the results obtained
it of the two forma are considerable, amounting to
' rent.

244

AMERICAN SEWERAGE PRACTICE

Pannley*s Formula, — This fornuila waa developetl by W. C. Pa
ley in his ytudic8 of conditions in the City of Clevcliiurl, prcparatofy
designing the kirge intercepting sewer known as the Walworth 8<iw<
These studies are described in Jour. Assoc* Eng, Soc.^ vol. 20, j>. 2€
where the formula is written in the form

Q = ri\(s A^i^

Parmley condiuled that i, the rate of rainfall corresponding to the tit
required for eoncentratton at the sewer iniets, should be taken at 4 :
per hour.

Gregory's Formula — Inoiiesenae^itishardl}' fair to include the Gre
orj' foriiiula ftinong those of empirical derivation, since it is based Uf
the rational formula Q = CiA . It is, however, interesting to compa
the results obtained by his method and assumption^ with those ba
upon the use of the empirical formulas.

As explained at length in Trans. Am. Soc. C. E., vol. Iviii, p* 458 et ne
Charles E. Gregory concludes that the coefficient C should be t^en i
a variable, dependent upon the time of ccmcentration t, and offers
expresaion C = 0.175^^^* for totally impervious areas.

He also suggests for the value of the precipitation factor i» the
pre^sion i = 32 /iV*. But t = l/\\ where I = the greatest length
the channel in which water flows from one extremity to the other of t]
area under consideration, and V — the average velocity of flow iu fa
per minute. Assuming values for I and V^ in terms of .4. and ^^ the fa
mula reduces to Q = 2,8 .4** **iS»*^''', which is the Gregory fonnula
quoted aliove, for totally impennous surfiices.

Weight Given to the Factors in the Formulas.-— For convenience
comparison all the factors except one in the several formulas may
assumed constant, and it is then apparent w^hat weight is given to th
factor in each of them. The results of this comparison are expressed 1
Table 73.

t\ble 73. — eixpokents of the powers to which the kse\ kh.%j.|
Factors ark Raised in the Various Formulas por Rin-opf

FormuU

Exponent of i „ . , «
(mtcfuiilyaf .Y"" ."^^^

-■ n

Hawkaley..

Adams

Barkli-Ziegler

McMalh , - , .

Heritig (A)

Heriag (B)

P/trmlcy.

Gregory (for impenHous
aurfzict!*), ,

0.75
0.833
1 00
1.00
1 00
IJJO
1 . 00

1 00

0.25

0.083

0.25

0,20

0.27

0.27

0.25

0 186

0.76

0.833

0 75 ^

0 8.n ■

0 s:{3 ■

0.833 fl

am "

^TIAfATING STOMf'WATER FLOW

THE USE OF McMATH»S FORMULA

r the foregoing formulas^ that of McMath is probably niost favorably
cnowti^ and it has been widely used, often ^ no doubt, without careful
iltidy into its applicability. While we do not recommend the use of

Values of "Q* in Cubic Feet pt r b«cQnd .
5 4 5 6 7 ft 9 JO IB to IS 30 40 50 60 TOM 90100

3 4 5 e 7 6 9 10 (5 20 30 40 50 60 70 &0 90 100

Area in Acres.

^fl mi -TlufiofT fruru srvvcnd areas of 1 tu 100 acres, by McMa*.h*8

fortnuJa.

*l»te or any aimilar formula when sufficient information is avaOablo for
^^ ttppUcation of tlm rational method, yet tliere are ca^ea whon its use

fu.t 1 r intcd. It \s abo convenient for u^e in rough prdiminary

, ai it can be employed very rapidly by means of tables

246

AMERICAN SEWERAGE FRACTTCE

or diagrama with aufRcient accuracy for such purposes, and indeed,
with greater preclsioa than the applicability iif the formuU warrants.

Allen Hazen has prepared tables for the rapid application of McMath'a
formula, which are contained in the American Civil tlng:ineer'H Pocket
Book (Second Edition, pp. 9G9-970), reproduced in Tables 74, 75 and
76. The tables are used as follows:

Table 74. ^Values of Ctv^ in McMath's Formula, to bs
Obtained as a Preliminary to Taking the Rtm-orf from tub
Succeeding Table, by the Use of the Identification Letters

(i taken on 2,75 IQ. p«r hour in ull ci<i3ea)

Percentage of totjil

tt^<^o covorecl by roofs

Value

Steep iJopes

Average

rial

Very flat

and pavements

ore

6Sp«i £000

•lop«^

"^^'l

■lop«a

Snndy ioil | Clayey aoil

100

100

0.90

5. .58=^

4,25 ^B

3'.24-C

2.47=D

73

70

0.70

4.26-i9

3.24 = C

2.47 = /?

1.89-^

53

46

0.50

3.24-C

2,47 = D

1.89-^ 1

1.44=^

37

28

0.40

2.47 -D

1 89=£'

1.44=f^

i.io=r?

25

15

0.30

1.89 = ^

1.44=/^

M0-(?

0.84=//

16

5

0.23

1.44-F

l,10-(7

0.84 = //

0 64 = /

10

0,18

1.10-G

0.84=//

0.64 = /

0.49=/

5

0.14

O.M^H

0.64 = /

0 49*=/

0 37 = AT

0

0.10

0.04 = /

0.40 -J

0.37-A'

0 28 = L

Table 75.^^RuN'OPr in Cubic Feet per Second pbr Acre, Corre*
spoNDiNO to Data in FoREGomo Table

Area A

in

^J

Identificati

on letters »nd correi^pondlnc Dumbera

A

B

C

D

E

F

G i H 1 I

i

K

acres

5,58

4.25

3.24

2 47

1.89

1.44

1 ]n t\ ui n *\±

n I a

n IT

50

a.ia

2.55

1.96

I 48

1.13

0.86

0,66

0.

!

70

3 34

2.38

1.S2

1.38

l.Ofl

0,81

0.61

0.47

^r.,.,., w. ^,

,, ^ ^

> ■ 1'.

100

2.51

2.22

1,00

1.29

O.tKi

0.75

0 ."17

0.44

0 33: 0 2.»

0 10

0,18

150

a. 72

2.05

1.56

1.19

0.01

0,69

0.53

0.40

0.31 0.23

0.18

0,14

200

2 89

1.93

1.47

1J2

0.86

0.05

0.60

0.38

0.20

0.22

0 IT

O.U

300

3.13

1.78

l.3fl

1.04

0.79

0,60

0.40 0 35

0.27

0.20

a. 16

O.U

500

3.46

1.61

1.23

0,94

0.71

0 64

0.42

0.32

0.24

0.18

0.14

0 U

7tK)

3.71

1.60

1.16

0.87

0.67

0 51

0.39

0.30

0.23

0.17

n i:*

0 m

l.ociO

3.98

1.40

1.07

0,31

0.62

0.47

0.36

0,2

■ ■ - ■ ' r- ' ■

XjiQO

4.32

1,20

0.99

0.75

0.67

0 44

0.3.t 0

^,000

i.67

1.22

0.93

0.7J

0.54

0 41

n -n A

3,000

4 96

1 12

0.86

0.65

0.60

0.3

1

5.000

6.40

1,02

0.77

0,59

0.45

0 :; \

7.000

fi.ftS

0,95

0 73

0 :>,■)

n 1.

10.000

6 3!

0 ««

n «7

0 '0

0 .3^

To iiM' tho tablrri iintj in f
Iwj oovervd by rocifs and irr

«>n HA the owe raay bo, and opposite this in the first table find a letter in
this ont» of the four oohitnns for stoep slopes, average slopes, flat slopes and
vory flat slopca that is aelcet;ed to represent the oonditii^ns. Wirh this
hiisT go to tiie second table, urn} follow vinder it to End a figure opposite
th« Afea moat nearly equal to the area under consideration. This figure

VdiuwofQ'in Cubic ftet per Second.
15 ?0 25 50 40 50 60 70 1O90I0O I5D_200J50 30O 400 S0O60O1O0I0O tOOO

'

'

'

^"^

"~y

[7

■71

7P

^

V

■>

7 >

A • Dnt/nag^ Arta iff A(rej.

Hour (apowjt. eqon^fgnt to Omc
' S - ^k^ f'n f^rptr 1000.

J

y^

0

V.

^ ^

i'-V

/

/i

/^

^

/

*-/

/,

%\

V.

/a

'/^

/-

i

^%

1 —

■»v

J

>

/a

/J

J

/a

^^

'l/A

Wy^

A

i^

A

/

' y

Y

y

t

/

//

3^

t

/>/

S

1

m

^^^

/

//^

V

t

i

^
v-'

J

/

/

K

'^M

///

L.^

I

/

/

A

/

/

'a

^

%

1

1

f

/

/

A

/

^^

y

-y.

^

W7

LZ'

y_

/^,

V/

^

' '''^if

yy

^

^^

■r~

,/

jf"^

4

yL

Vr

r'^^^U

^/

>

y

/

^y

l/^

A

f

A

^

^^y^

r/

/

i\

V

fA

A

r

/^

ft

^

^f,'^

/

^

p^

n

•.'^

^

Ys

'//

^

-A

'//

/

'^J<^\

<^

//'

*^i^

^'

^

^J

'/ >

^yg

ry

5^

€i

W/-

5^

Y

/

J

^.

'' /,

t^!"^^

/a

m

W:

'/y^
<^'<^

^\

/

/

f

/

/A

^^

M

<■

A

/

r

/

//

'i

^M('''

■y}

w

/

/

/,

V

^v

r//

^^

f

-

/

Q IS 20 25 ^0 40 50 60 10 6090)00 ISO 200 250 300 400 500 600 TW 100 tOOO

Area in Acres.

fto. 105, — Runoff from sewered areas of 10 to 1000 acres, by McMath'a

formula.

*^rtM?nU the nin-off in cubic feet per seoond per acre that is to be used,
wwi lliis is to be m\iltipUed by the number uf atTes. The product is the
*?^i*atity of stonn water in cubic feet per aeccjnd to be provitled for in the
^•^er- The result is only roughly approximate and is to be accepted with

248

AMERICAN SEWERAGE PRACTICE

Convenient diagrams for the solutjon of McMath^s formula are giir
in FigH, 104, 105 and 106, In using tlicse diagrams, start with the gi'V
area at the i)ottom of the diagram and follow a vertical line to it» int
sectinn wilh tlie sloj>c line; then follow a horizontal line to its inter
tion with the ci line, (having first found from Table 77 or by multiplte

100

ISO

Valines of Q In Cubic Fe«t per Second
WO ?5D3O0 400 500 6OO7O0»0O lOOO tSOQ m^ g$00 3000 4000 SOOO

^^

—

—

-r

> >

y77^

T^Z:

55^2!

A • Drai{fog« Ama In Aires,
' € - nun-oW Factor,
- / ^ Majt.Ratwef Fitfnfallm fmhtjper ^

hoi/r(approi. equiv^hnt to Cubic

FvefptrJiCimaperAcm.)

/

/A

Z'^^/-

/

///

W-/.i

y

y//^

%^>

^y

/

i

S'

ilCf

4in

fttt-p%

tHXH

7.

/

'//

^A

/

^^

/

>

/,

WF:.

w

/

■A
A

/

/

;^

i

m$t

\

p

?'

/

/.

i

I>

/,

\

^

f/^\

y'jA^

/ .

^/

P^v

*• /

' /

//

y?

4

r '

/

K

/

%.

^

?.

V-

A

./J

'/

W

W. '2

A}

Y

%

V^\

'^

V.i

V

/^'

r"^'

A

/

/

y/

^M

m

"^A

^

^

\-'/.

/y

//

/a

^r

^^"

4

'^

/.

//

/

M

i

Z%Z0^

>.

'^

<

/

/a

y.

/

/

i

^

'^

i

^

/
/

/

100 ISO \m t50 300 400 500 &D0T0Q900 rOOO 1500 20OO 25003000 4000 5000

Area in Acr«9,

Fwi, 106. — Runoflf ffom sewere<j area* of 100 to 10,000 acres, by McMftti

fonnida.

tion, the product of the assumed coefficient of nm-olT C and the inl
sity of precipitation i) from this point follow a vertical lino i- '
of tiuantititjH at the top of the diagram. For example,
=^ 100 acres, i = 3 in,, c = 0J0> and S « 15, Tlien </ * \\\ wAm.
The valued of a for use with theae diagram?^ "^ - "Vf^n in Table 77.

76t — Value

OF ci\/5 (in Mc Math's Formula} Used or Recom-
Various Case^. {REARRANciED prom Ha2en)

I'U«

EljiffiQeer

eiVs

Ulitoort*.

Keniketh Allen

4,25-5 58

....

P^*^"

Jlcring, Gray and
Steam a. ;

4 25±

B%. LouLs

iMcMath ......

3.24±

0-84

Winniprj^ ... ,

Very flat slopea.

Chii^KO

0 49±

Developed areas
100-10,000 acrea.

ChicAKo

0 37±

CJudeveloped areas-

WaU^rahtxls in

Fanning

LIO

Undeveloped, areas,

Ki*w England.

640 acres or over.

bBo)«ton (8Uiny

Francia, Hcrschcl

1 44

8,000 acres prospectj

Bfook).

ttnd Clarke.

of future devel-
opment.

JVlohawk Valley »

Kuichling .

2 47

Floods which occur

nutuml C5c>«di-

occaaionaliy.

tiima 10,00<> to

l(IO»OtXJ acres,

\ AR-l firi

Floods which occur

tUfep sloiK*d, gen*

rarely.

emlly impervious

ioH.

Tablb 77-— Values of ci won Use wrxH Fioa. 104, 105, and 106

i

1

1

2.25

2.50

2 75

3 00

3,50

4.00

1 0 3

0.68

0 75

0 83

0.90

1.05

1 20

1 ^^

0 90

too

I 10

1.20

1,40

1 60

1 ^^

1.13

1.25

1.38

1.50

1 75

2 m

T oa

1,35

1,50

1.65

1.80

2,10

2.40

1 0 7

1. 58

1.75

I 93

2 10

2 45

2 80

g 0 75

1 69

1.88

2 m

2 25

2 63

3.03

1 0 8

1.80

2 00

2.20

2 40

2,80

3.20

H 09

2 03

2 25

2 48

2.70

3 15

3 60

FLOOD FLOWS FROM LARGE DRAINAGE AREAS

The foregoing empirical formulas have been derived for use in sewer
f oenigti and are properly applicable only to comparatively small water-
F tbftdit, seldom exceeding 1000 acre^ in extent, although they have occa-
j ttoually been used for much larger areas. It sometimes becomes neces-
**f>', in drainage problems, to consider much larger areas, especially in
i where a creek passing through a city is to be converted into a cov-
I «rnl cbnricL
Jt ig a matter of common knowledge that rain-storms cover a some-
i limited areSi and it is a fact, though not so generally recoguized^

250

Ai\fEmCAN SEWERAGE FRACTWB

that the more severe the storm, imually the smaller the area th
covered by it. Precipitation of great intensity is usually limite^l i
very snifill area and it often happens tliat the rainfall is not uniforiD (
the whole storm area, but that small tlistricts receive much more pred
tation than the area as a whole. Large watersheds may include
steep and gentle slopyes^ imper\'ious and pervious areas, wooded
arable land, so tliat portions yielding their run-off rapidly are off-j
others the yield from which is retarded. For these two classes of rea
the natiu-e of the rainfall and the character of the drainage area, ;
obvious that the rate of run-off from a small watershed will be
greater than from a large one.

Many attempts have been made to reduce to formulas the info
lion relating to ruii*off from watersheds, so that, given the area ol|
watershed of a stream at any point, the maximum rate of discharge I
be computed with reasonable accuracy. A few of these formulas uf <
parativcly recent origin are of interest and are graphically expre-^
Fig. 107, in which two curves of the McMath formula are also plot Uid
comparison.

KuichJing's Formulas, ^In the report on the New York State ]
Canal, 1901, Emil Kuichling, after tabulating the various recorils of I
off and drawing diagrams of all available floo<i discharge records, ;
pared two curves ** showing tlie rate of maximum flooil discharg
certain American and English rivers, under conditions comparaM^
those in the Mohawk Valley,"

The formula of the first curve gives rates of discharge which ma
exceeded occasionally, and is as follows;

44,000
^ = AT + lTO + 20

The formula of the second curve gives rates of discharge which i
eixceeded rarely, and is

^ 127,000^ . . .
*^ "M + 370 "*" '^
This is for drainage areas of more than 100 sq. miles. For dli
age areas less than 100 sq, miles in extent Kuichling has reo
suggested the formula (not heretofore published):

Kuichling has nUo prepareti a formula (n«>i m nuttijn- p^llJll^(^
for floods which may be expected to occur frequently. It ij*

25,000

^ ^M + 125'^

15

Kuichling notes that all of these formulas aro intendod l4>
to hilly or mountmnous regions, suoh as are found in ihts Ne

0f(n Cubic Feet per Secad,
wbic Feet per Second rer Square MHe.
irea frt Square Miles,
V M Acres,
me in which Flood of Magnitude Shown

"f Rainfall, Inches perH our.
y>€ of Drainage Area it Feet

I

v'^m^MM^u^ g'js:^ J, 'jsi^

:,V»«yii^___ __ i

el

\

40V

300

200

(0(

L

&00

900

1000 -.Q

<fwiii«#a«i t<<9

FOHMULAS FOR ESTIMATING STORM-WATER FLOW 251

, and North Atlantic States, and are probably also applicable to a
[ country having a clayey surface soil,

'5 Formula. — In Wat«r Supply and Irrigation Paper No. 147

8. Geological Sur\^ey, E. C. Murphy suggests the formula:

^ M -h 320 ^

15

and £ddy*s Fonnala*— The authors have suggested^ the
I (not heretofore published)

440

3/«.»7

1 formula gives resulta approximating very closely those of the
uilafor areas between 100 and 250 sq. miles, and larger
rvas beyond these limits, and is intended to represent floods
I may reasonably be e-xpected near Loui&ville.

^nnulajs Q represents the run-off in cubic feet per second per

aid M the area of watershed in sr4uare miles.

r*8 Fonnialas.— The most recent and perhaps most exhaustive

' flood discharge of streams, is contained in a paper on '* Flood

I," by Weston E. Fuller, in "Proceedings'^ Am. Soc. C. E., May,

Fuller is the first to publish a formula in which the interval of

JcorreHpondmg to frequency of floods) appears as a factor in a

^lor flood discharge^ although it has been recognized for many

at tlie greater the interval of time, the larger the flood which ia

I to occur within that time. It must be remembered that in any

iy we deal with averages and probabilities. Because a flood

m magnitude is likely to occur once in 100 years, it does not

tlmt 100 years will elap^ before the occurrence of such a flood*

of this magnitude Hhould occur within 5 years, and none

for 195 years, the average occurrence would «tiU be once in

I aotatioQ usimI iu Fuller's formulas is:

Q » gntateit 24-hour rate of run-off in a period of T years, in

cubic fiM*t per second,
Imu^ Uu* greatest rate of discharge during a maximum AcmkI, in

eubic feet per seeoiid,
Vu* the average 24-hour flood for a series of yetinii in eubic U%ii

per second,
I * Wngth of period in yeun,

oonataot for a given atreain at a given pCAtil of

252

AMERICAN SEWERAGE PRACTICE

The f onnulas derived by Fuller from a study of all available An
records are:

<?= Qa.(l + 0.8 log T) = CAf o»(l + 0.8 log T)
Q.a,= Q (1+ J,:,) = ^^°'(1 + 0.8 log T) (l + ~;i)

In this study it is assumed that the average annual flood flow i
determined with sufficient accuracy from a record extending
period of 10 to 15 years, in other words, that the average will
materially affected by increasing the length of the record indefini

Assuming the maximimi rate of flood flow (Qmax) from ^ di
area of 100 sq. miles during a period of 100 years, as unity, t
responding maximum rates of flood flow for other areas and other ]
of time would be as shown in Table 78.

Table 78. — Relation between Maximum Rates or Flood Floti
Areas op Various Sizes, and for Periods op Various Lengi
According to Fuller's F\)RMula (with a Constant Coefpicie

Drainage
ar*»a,

Du

ration of poi
60 1

'iod. in yean

1

10 !

100 1 500 1

»q. mi.

]

[lolativo magnitude of maximum flood discliarge

0.1

5.08

9.15

12.0

13.2

16.0

i:

1.0

1.93

3.48

4.55

5.01

6.09

(

. 5.0

1.04

1.87

2.45

2.70

3.28

10.0

0.81

1.46

1.91

2.11

2.56

50.0

0.47

0.85

1.12

1.23

1.49

100.0

0.38

0.69

0.91

1.00

1.21

500.0

0 24

0.44

0.57

0.63

0.77

(

1,0(K).0

0.18

0.32

0.46

0.46

0.56

(

5,000.0

0 14

0 24

0.23

0.35

0.43 (

10.(XX).0

0 12

0 21

0 27

0.30

0 36 (

Table 79. — Values of the Coefficient C in Fuller's Fc
FOR tYooD Flows, for Various Sections of the United Stat

St'ction
Atlantic C\>ast

No. of

drainage

aroas

126

'

Values of C

' A'

Maximum
140~ '

Minimum

30.0

St. I.AwrtMiw and Uppi^r Miss-

39

55

7.5

issippi.
Ohio Basin

:^s

150

45.0

Missouri antl LowtT Mississippi.

74

55

2 0

Colonido Kiver

1 24

: 45

4.0

Pai'itic CVast

SO

' 210

6.0

According to Kullor's studies his forniuhi expresses the general
variation of flood flows with area aud length of period. It k ncr

FOnMVLAS FOB KSTI MATING STOHhf -WATER FLOW 253

lea difBcQlt to solect a proper value of C^ unless tho taformation avaU-

'- r ronHlderatioii Lh suffident to enable this to be

»tidition« maj" affect the value of this coefficient

th&i IX would be dithcull to select a proper value even from the extensive

'-^ If^ jz;rv^n by Fuller. The range in the coefficients computed by him

iwijby Table79:

Fuller does not recommend any value of C for general use when
mfomiation may not be available for the selection of a coefficieut by
coniptri»on with some Btream for which C has V)een computed. In
fa dtJkRnun showing a comparison of his formula with other formulas
\m HocmI discharge he presents tliree lines representing his formula^
*nlh values of C - 70, r = 100; C = 100, T - 1000; and C - 250,
J « lOOO| respectively. It may be inferred, perhaps, that a value of
C • 100 would be reasonable for ordinary use.

With regard to the length of the period to be used, Fuller says:

'*n(<»d* hjivt' oc'ctim^d on st>T«e rivers during the la«t 20 years whiiVh,

ftMfmfclh . iwcjuld be rei»«''vted in not less than KKK) years* If worlcH are lo

I t!c>cKi« pqunl to the greatest that have been obscrv^ed^ a value of

T lOtXl sbiiuld be used. Such a flood or a greater one may occur

u fwvT at any time, but it is not likely to come sotin on any particular

ui. It miiJMt be remembered that the use of 7^ = IIXK) does not mean

tbubc corre^py ruling fliH>d will come at the end of 1000 years, but that the

rfrtJioeji arc even that it will occur some time during a ptTiod of lOOO years.

It mean*, aL>o» that the chances are 1 to KXK) that it will occur in any one

y«r>«r i to 100 llmt it will occur in 10 ye^rs, or I to 10 that it will ocnir

wn^in A w>nlury. The selection of the proper value of T then becomes a

<;tieitiuD of what ckaiiee w« ran afford to take."

COMPARISOH OF FLOOD FLOW FORMULAS

J* *ompari*»on of the flood run-o0:* from drainage are^aa of various sm»^
A^miing lo the vsrloua formula:) for fiood discharge, b ^ven in Table
^. mA [^ almi shown bf iJie dtssiviD, ¥%%, 107.

Other FoiBittl«i>— fevtial ocber fonnuIa2§ have been iuggeitod, And

^ quilted hf«re merely f«r relijrwie©* It is not believed that any of

^^ " 1^^ iitlj appBiMiMp to Amertean condittotia to be used as a

of flood dMianVBi,«3cet|il poosibty the ctthrwt formtilkay

tbly wpifiitaMe ia tamm eomparable to these for which

oA

iQ iheao fo

mial dinhftf]^ i r '^ per aecomlf

arm nf vafiitnJu'ii ..* ^^^^ax^ mHea,

Imgth o< wateniied to milee,
I btftaidth of wirterahiri in tssS^
• a4 ^ *

^^m 254 AMERICAN SEWERAGE PRACTICE H

^^^H Table 80.— Comparison of Various FoRMtiLAs row Flooi^II

OF Stheams, in Cubic Fekt per Second fee Square Mm

FormuU

Dmizwffis Ai^ift. if - t

1 1

5

10 : 60

M.

Kuichliog, No. I (occttBional)

277

272

264

220

is; .K \i

<^'t>00 . ^

« - ji/ 4- no + ^

I

KuicbUo*. No. 2 (rnrtO

.. . .

....

.»•.

...

277163

>«^

127.000 (f or draiimgc nrcM of

Q " M -^370 '^ ^'^ more thAD 100 tq.

j

miles).

tisi

Af -i- 32 lew than lOO iq. milea).

1070

9fi6

844

437

* - ♦

• «

m

■

Kuicbling, No. 3 (frequent)

214

207

aoo

IfiS

lat

■

'20.000

■

« " .If -fm ^ *^

■

1 Murphy (Max. for N, E, U. 8.)

lei

ISO 167

141

124!

1

■

46.7ftO .

\

■

« " .V + 320 "•■ ^^

■

Metciilf iind Eddy

440

^e

237

164 127

3^B

440

n

« - ji^e.tl

McM»ih {C - 0J5. i - 2.75)

an

41l»

363

202

230

165

4

Q - riH\/* t - 10

JJ

^^^^^M

BQrkli-Zieglw: (C - 0-9: i - 3)

6U

408

344

2;30

IW

>#i

^H

Q - CiAV^i- i - 10

^^

m

^^H

Fulk-r: Qp,,, - CAf«-»(l +0.8logr)(l ^ J^^Tt)

^^^m

C - 70. r - 50

4(»5

2m

200

122

fH)

«a[ 1

c * 70, r - 100

64fi

204

Xi*^

i.o' J

C - 100. r - 1000

1020

hW

43m

•■; ic

c -» 2ivo, r - toix»

2550

laZft

1070 ...r.„r,.

.^^

Fa«ft/7i^« Formula.— <i = 200 3/^. This formula was

jI

^^^H J* T, P'atming in Ms *' Treatise on Water Supply Engiaeering

^^^1 It ia based upon a comparatively small number of obsen^a

^^^^^^ American streams*

^^^H TalboVs FafwtOa.— Q = 500 3/^*. This was intended for ua

^^^^^^ prairie states only, and for areas up to 200 sq. miles.

^^»^ Coola/s Formula.— Q = CM'\ where C = 180 to 200.

^^^H C. B. dt Q. R, R. Culvert Formula.-^ =3,000 M /(3 -h 2 ^

^^^^ Duns Table.— (For A. T. & 8. F. R. R, Culverts.) This i

^^^V follomng rates of discharge in cubic feet per second per squ

^^^^^^ from areas of the given number of square miles. mm

^^^^m .\rca 50 liX) 500 Um ^^|

^^^^1 Dischargt^ 1,000 910 G79 302 212 U2 f*.4 ^^M

^^^H Hfmter*^ Cylptri For mula.--Q ^ 27 \ A^ ^^|

^^^^^^^^^^^^^^^M A I'mfu fVif 4j|i^t~iA rkt t nr. «i.4 1*1:1 riTii itiIl

*J^^^^^^M

^^^^^^^^^H a^vLTiiKt' oiupt} Ul lllL* el-l LiLlfHi m >'

^^^^^^^H

i-"" 1

FOUMVLAS FOR ESTIMATING STOHM-WATER FLOW 255

iln ui*icpliUtiod in Engineering Nexm, May 1, 1913, It is based upon

nitMhi»<l of t^torm itewer desiKn, working from the cimc of
uiufall at St, Louis as derived hx Horner, and introducing

n approxitiiatiotiR.
bui * '' >nida.—<i = CM"^^, This is cunsiderably used by irri-
lioj. - in India. C may vary between 150 and 1000, and is

uolly taken as 825.

i^ypeji' farmtdn. — <?== CM**, This formula is also extensively used
fmiia, osuaJly with values of C as follows: within 15 rniles of the coast,
= 45<J; from 15 to 100 miles inland, C = 503; and for a limited area

tlic hilb, C - «75.
Drtti{fi'\ F<frmu!a,—Q = CM IL^^, C is usually taken as 1300.

formula is l>ehcved to be based upon studies of rivers in India.
ifConmlVs Formula. —

Q = -45.796 + \/2097.28 + (457.96M X 640)
This formula waa proponed in 1S6S, in a pap^r contained in Proe.
C\ E,^ vol, xxvii, and is said to have been based on .studies of
frni in Europe, India and America.

Croty* Formula,— (i = 440 BN hyp. log SL-fB, where A'' varies from
l37to 1,95, the lower value applying to very flat watersheds. Thi.s for-
Proc, Inst. C. E., vol, Ixxx) is intended to apply to Indian

, (im^Ulet's Formula.— Q ^ 142IM/(3.11 + 3/) for Swiss streams.
Italutn Formula,— Q = CA/ /(0.311 + Af), where C = 1819 for river«
M 2600 for small brooks in northern Italy*

\P<m$nH*8 Farrtttda,^i ^-j-IMi +~^/ when C has an average

JUrof 1010, and R is depth of rain in inches per 24 hours, A/j is the
» of the hilly or mountainous, and A/u the area of the flat portion of
i ^l«n<bed.

CR'mMS^^

in which C varies

IS6 for rouRh, natural drainage areas, to 608 for smooth, corn-
level and impervious areas, such as may occur in cities.
1^ II annual raiaftdl in inches,

• iiverage wlopti of stream from source to point of observ^ation,
-, . f ... _ . ,. . |-^^^ ^^^ ,^l^ ^, ^^^ ^^^ g^^ ^^^^ p subject to overflow.

:: Iributed in a uniform manner tUrout^iOUt the biusin
709F\

1

-Sin(t.ia j^j^,^

sittt urea k concentrated at the lowest point, then
. / , 141SA

250 AMERICAS SEWERAGE PRACTICE

Laukrburgs Formula,^Q = -^Va ■ 7)oo2^j|/ + .053 j intended to
apply to floiHls resulting from a continuous heavy rain of 3 or 4 day«
duration at an average rate of 2 in. per day.

FLOODS

Effect of Snow and Ice. — It may happen in some cases that the maxi-
niuni flow of streams will occur when a warm rain falls upon snow already
on the ground, or when the ground may be coated with ice in such a man-
ner as to present a practically imper\'ious surface, as well as allowing*
portion of it to melt and run off with the rain. In these cases the total
run-oiT may amount to 100 per cent, of the precipitation, or even more.
In the case of streams of considerable magnitude, where the time neces-
t>ary for concentration is several hours, or possibly even days, and where
the maxinmm rate of precipitation, which probably prevailed over but
a limited area, is a comparatively small factor in determining the maxi-
mum rate of run-oiT, maximum flood conditions are particularly likely
to occur from rain falling upon snow or ice.

In such cases it is desirable to estimate the approximate equivalent
of the snow or ice, ui>on the ground, in terms of depth of water. The
United States Weather Bureau "Instructions to Co-operative Ol>ser\ers"
state that when it is impossible to measure the water equivalent of snow
by moltini;, oniMenth of the measured depth of snow on a level o\^Ji
place is to be taken as the water equivalent, although it is recognized
that this relation varies widely in different cases, depending on the wet-
ness of the snow. The water equivalent of snow may be as great iw
one-seventh or as small as one-thirty-fourth of the depth of the snov.
These figures apply to recently fallen snow; the water equivalent of
snow which has been on the groimd for some time and which is there-
fore conipact(Ml Xo some extent, would be greater. R. E. Horton states
in the "Monthly Weather Review," May, 1905:

All records indicate thai for the hoavy and persistent snow accumulalions
occurring in New York and New England a progressive growth in the water
equivaUnt per inch oi snow on ground will usually take place as the scas*in
ailvanros, due to compacting hy wind, rain and partial melting, and to l^
weight of the su[)crincuml>enl mass on the lower layers. The water cquiva-
knt of cominicitd snow accumulation is commonly between one-third and
ont'-llfth, or at least ilouble that for freshly fallen snow."

The relatitni bet we(»n the thickness of an ice layer and the correspond-
ing (le])th of water is more uniform, and for practical purposes 1 in. of
ice may be considered as c<iuivalent to 0.9 in. of rain.

In the <'nse. of sewer districts, maximum run-off is much less likely to
occur from rain falling upon snow or ice. Rains of p-eat intensity are
of comparatively rare occurrence during the reason when snow or ice

lyORSfULAS FOR EST! MATING STORM-WATER FLOW 257

formed. Moreover^ the effect of snow upon the ground would u^u-

be to retard the flow of water, the snow acting as a sponge during

time of heaviest precipitation, and causing the nin-off to be at a

lore gradual rate than the minfall during this portion of the storm.

|lt 19, however, postsiblc, under extreme conditions, that maximmn run-off

might be caused by a warm rain of heai'^'^ intensity following after a

[period of comparatively light precipitation, by which the snow has been

iturated and nearly melted, so thut the maximum rate of run-off might

[even be in excess of the greatest rate of precipitation, and the possibility

'of tltii* condition must always be borne in mind.

Records of Flood Flow of Streams. — Table 81 contains some records
^^of flood flow of streams in the United States.

iLE 81.— Drainage Area and Maximum Discharge for Various

/VM ERIC AN RrVERS

Draio-

Mm. dis.

Hsme of Btrfam und

ftge

cu. ft, p«r

Date

Authority

locality

»reft,
■q. mi.

B€M3. per
sti. mi.

Bodlonj|f'r«.k. UticA, N, Y.

1.13

120.40

1004

U, S Geol. Sur.,W. 8. P. No 147

^^

Sylvan CI en Crwk, Naw

M8

f M.58

19(H

D.S.G^ol.Sur..W.S,P.No. 147

■I^Jftofd, N Y.

\ 277.00

W, E. Fuller.

^^tj/K^^^^^'' Hunts Fond.

1 70

25.30

"--

N. J. Geol. Sur., 1894 Pt. 4

StdarrL Fftclofy Creek. New

3.40

/ 100.62
\200.00

1004

U. 8. Oool. 8ur.,W.S. P. No, 147

Hertford. X. Y.

1005

U, 8. Ocol . 9ur.. W, S. P. No. 162

m

4.40

48.80

1004

U.aO0ol,8uf.,W.8.P.No.l0a

m

N, Y.

Mm4 Brook, Skerhunm.

6-00

2fla.oo ;

1005

U. a. GtoI Sttr.. W. a P- No, Wi

N. Y

8Jtinni.T Cr««jk, Mamuville,

N. Y
CrtldnpritME Brook. Aahlaud.

ft,40

124.20

1891

U. 8. B. En«ni. D. W., 1890

0.43

48.40

188Q

Trans. Am, S. C. E.» Vol. 25

■

M«»

■

CmjIoo Rjvef, 8o, Branch.

7.80

73.00

1869

Trans. Am. 8. C. E., Vol. 4

■

N. Y. (3()-yr. r<*oord).

■

MiU Brook, Ediobtooe,
K. Y.
Woodhull Tleavrvoir. Hcrki-

0,40

241 00

1005

U. S. O. S., W. 8. P. No. 162

9 40

77 SO

1860

Trans. Am- Soc C. E., V'ol. 4

H

mirr. N Y.

■ '

Stoiiy Brook. Boston. Mmm.

12,70

121 00

1SS6

Kept, Stooy Br. Flood Cora.

■

Mjtuhati Itivtsf. Holyoke,

13.00

108.00

Jamos L. Tighe

■

M*i««

P

OrtBi RivOT. Wcatfield*

14.00

71,40*

Rept. of H, F, Mills

sum

Hwmf^wood Luke. N, J, .

1ft 00

68 00

N. J. Geol Sur.. 1894 Pt 4

%'ii' rtiv fttu]>per

16.20

30,00

......

V. 8. B, En*. D. W , 1800

d -town, Mius.

.

WjI Hiv »tIo*^«?r

IC 50

34 . 00

Crui : .. W. Bmneh,

30.47

54 40

1874

B. M. Treinan, J, J, R, Croes,

N, Y, lau-yr. rwortl).

T«»ch. Quur. ISOt.p. 325.

i__

Rmver D»iij Creek, Alton*,

20 70

111 on

--•-*.

U. 8 B, Eogri* D, W,. 1M99.

■

S Y

flow fur day of majuiuum diiichar]|f9.

258

AMERICAN SEWERAGE PRACTICE

Table 81. — Drainage Area and MAxmuM Dischargb for Vabioub
American Rivers. — Continued

Drain-

Max. dis.

Name of stream and

age

cu. ft. per

Date

. Authority

locality

area,
sq. mi.

sec. per
sq. mi.

Beaver Dam Creek, Bridge-
port, Conn.

22.23

200.00

1906

Trout Brook, Centerville,

23.00

60.6

1875

U. S. B. Engrs. D. W., 1899.

N. Y.

Pequonnook River, Conn

Wautuppa Lake, Fall River,

25.00

157.00

1905

28.50

60.70

1875

Rep. N. Y. Baz«e Canal. 1901

Mass.

Trans. Am. 8. C. E.. Vol. 4

Wautuppa Lake. Fall River,

28.50

72.00

1875

Trans. Am. 8. C. E., Vol. 4

Mass.

Pcquest River, Huntsville.

N.J.
Pequest River, Tranquillity.

N.J.
Sawkill, near mouth. N. Y. .

31.40

19.30

N. J. Geol. 8urv., 1894 Pt. 3

34.80

18.70

35.00

228.60

1896

U. S. Geol. 8ur., W. 8. P. No. 35

Whippany River, Whip-

r 38.00

84.20

1896

U. 8. Geol. Sur.

pany, N. J.

\ 37.00

61.02

1903

Cayadutta Creek, Johns-

40.00

72.40

1896

U. 8. B. Engn. D W., 1899

town. N. Y.

Six-mile Creek. Ithaca, N.Y.

40.00

132.00

Emil Kuiehling

195.00

1905

U. 8. Geol. Sur.. W. 8. P. No. 163

Mad River at Camden.

46.60

22.10

Rep. N. Y. Barge Canal, 1901

N. Y.

(U. 8. B. Engrs.. D. W. 1899.)

W. Canada Creek, Motts

• 47.50

34.10

1894

U. 8. B. Encrs. D. W.. 1899

Dam. N. Y.

Little Conemaugh, So. Fork,

48.60

205.70

1889

Trans. Am. See. C. E., Vol. 24.

Johnstown. Pa.

1891.

Sauquoit Creek. N. Y. Mills.

N. Y.
Rockaway River, Dover,

N.J.
Mill River. Mass

51.50

63.40

U. 8. B. Engrs. D. W., 1899

52.50

43.00

N. J. Geol. Surv.. 1894

58.00

15.50

Reo. N. Y. Banre Canal. 1901

Oneida Creek, Kenwood,

59.00

, 41.20

1890 U. "s. B. Engrs. D. W., 1899

N.Y.

1

1

Flat River, R. I

61.00

120.90

1845 ' Trans. Am. S. C. E.. Vol. 4

Camden Creek. Camden.

N. Y.
Pequonnock River, Mac-

61.40

1

24.10

1889 U. 8. B. Engre. D. W., 1899

62.00

90.80

1903 :

opin. N. J.

1

Nine Mile Creek, Stittville,

62.60

124.90

1898 U. S. B. Engrs. D. W., 1899

N. Y.

1

Otter Creek, N. Y., Castor's

63.00

30.90

' 1869 Rept. N. Y. Barge Canal, 1901

Mills.

1

1

Wissahickon Creek. Phila-
delphia, Pa.

1

64.60

43.50

; 1897 r. S. Geol, Surv. 20th An.
I 1898 Rept.

Musconetcong Creek, Sax-

68.00

15.90

Rept. N. J. Geol. Surv.. 1894

ton Falls. N. J.

1

Pt. 3

Kindorhook Cr.. Garfield,

.\. Y.
Sandy Creek, So. Branch,

68.20

1

1 68.40

9.00

i

87,70

1

1S94
' ! 1890

r. S. B. En«r8. D. W.. 1899

Allendale, N. Y.

1 \ 1S91

Sudbury Hivor. Framing-

, 74.05

44.30

1SS6 ' Trans. Am. S. C. E., Vol. 25

ham. M:iM.

1

1

'

RMULAS FOR ESTIMATING

STORM-WATER FLOW 259 ^H

81. — Drmnagb Area and Maximum Dibcharge for Various ^^|

American

lilVCRS,-

—Cantinucfi

^H

Drain-

Mtt*. din.

^^^M

t» id •ireain mnd

locally

Areo,

cu ft. ppr
Bee. per

Date

Aulhority

^M

•a» mi

m\. mi.

^^^M

BvfT, Conn

75.00
77.50

30.40
12Q.30

H

Toch, QuAr M. I. T., 1801. p.

•

242. Tmim. Am. 8. C. E., Vol,
Eng. W»ler Dept. City or

^H

ty Rtrvr. i>mmln«-

^H

UmL

78. oa

41.38

1807

BtiaUiti.

^^^M

iftotk Mvtf, Poinp-

78. OU

55.78

1002

V. 8. Gffca. SuJPV,. UDpubliAbvd

^^^M

1 J.

^^^M

■itin njv#r. Cooo. .

79.00

78,10

Ch Eii«T. U. a. A.. 1883,

^^^M

iCfwk, « ml. •bove

80.80

15.80

^M

K.J.

83.40

0.00

,

^M

imr«r. IkUa

a4.50

71.04

1850

Trani. Am. S. C. E., Vol. 4

^^^M

laopk Rtvwr, Riv«r-

84.70

52.50

18S2

Kept. N. V. Barjse Cii«al, 1001. .

^^^M

K 1

GeoL Sur. N, J, 1804

^^^M

Kim, RaMb RIv«r,

85.00

23.2

lat All. Hop Mc. St, W. Stor.

^^^M

p.

Com. 1010, p. 350,

^^^M

todtaM Cr«clt, Craa-

03.30

66.50

1860

^^^H

MilKX Y.

^^1

t Rirer «t ChatJimnt,

100.00

17.20

1003

V. S. OeoJ, Burr. (unpnbHiihrd)

^H

iwi, N 5

102.00

f 112.5
\ 13R.00

1S85

H

W. k Fuller

iHim, BfMi

109,00

104 6

Tr. Am. 8, C. E., Vol. 4

^^^M

1 HSr«ir. Mftbw«h.

119.00

105.1

W. 8. and 1, puperv 147, p. 185

^H

lEIm.Conn

118 00

51.8

R-p Ch Enir . V. S. A.. 1878,

^H

kty EiT«r. Eoontmi,

121.00

e2.6

1003

^H

mt Blv«f» Pomplon.

]A2,00

A5.0

1S82

^1

i. ' '■■■ ^ a L,.-.

190.00

56.0

1867

Tr. Am 's. l, K.. Vol 4

^H

b^ i:ivi.r, C5*r-

240.00

13.0

1003

lit .\d. R«>p. Me. Hi. W. 8t-

^^^M

ir r reeurd).

Com.. 1010, p. 350.

^^^H

*' Fotctof t.

380.00

77.6

1009

l0t Ati. Hep. Me. Et W. 8t

^^^M

i -1}

Com., 10 10. p, 350.

^^^M

pewit iiiv«f« Pttt^

314,00

22.8

1900

I«t An. Rep. Me. 8t W. Si,

^^^M

iMft (»>rr. fi»«irtl).

Com., 1010, p. 350.

^^^M

fcUiw. N Y

3A8.82

74 0

1854

Tijch, Qunr.. 1801,

^^^M

^wit Riir«r. No.

340 00

40.3

1004

1st An. Rep. Me. St W, 8t.

^^^M

hgte. (7-yr. tworfl).

Com,. lOlO, p 350.

^^^M

^HikiTw. ftftlmoQ

3AO.O0

151.4

1878

Rept. of H F. Mill*

^H

^^KCcntor Coawmy,

388.00

36.7

1007

Ut An. R*p, Me. 8t W, St

^H

^Bmyt r nil

Com., 1010, p. 3.V)

^^^M

r ^'n«o

420,00

33.0

1806

iBt An. Rep, M« 8k W, 8t.

^^^1

P^ ITft)

Com.. 1010. p. 350.

^^^M

► -^ ■ n^ef'

4II4.00

23.0

mw

lit An. Rep, Me. St. W. St

^^H

Bv»

Com., 1010. p. 350.

^^^M

^■^^iu>rr <_'uhm*htii>

620.00

115 0

1013

Alvord ttod Burdick.

^M

^^^H

J

^ 260^ AMERICAN SEWERAGE PRACTWE^M

^^^^^H Tablic 81,— Drainage Area akd Maximitm DiacaARGc fob]

American ^vEns.—CottHnucd |

Drain-

Max, dia.

N«mc of stream and

air©

ou. ft. per

Dat«

Auibority

locality

area,

Bee. per

H<). mi.

*q. mi.

S»ody Rtvvr. Mftdbon Me.

aso

21.3

l»07

l«t Aa. Rep M«. 0

l5-yr. r«j*irt|>.

Com.. 1910. p. 360 '

Moow River, Rock**oot.

060

10.0

IDOS

I fit An. Rep, Me. ^

Me.

Com., 1910, p 35di

Dend River. Th« Forki, Me.

878

21.0

10U7 [

Ut An. Rep, Me ^
Com,. 1010, p. 3-50.

Fish niver, WftUagmM. Me.

890

10. i

1008

lit An. Rep. Me, 4

(t>-yr. rwordK

Com,. 1910. p. 350v|

Penobscot River, E, Drench,

1,100

23.4

1009

Ist An. Rep, Me. fl

Griudstofie, Me. (tKyr,

Com.. 1910. p. 35d

Tt*corcl),

*Sl Croix River. Woodland,

1,420

14.3

IHtJd

Ifli An, Rep. ^"^H

Me. (9-yr. record).

Com.. 1910, p,WB

MuttawHoikctHK Riv»»r, Mat-

1,500

lfl.3

1907

lit An. Rep. Me Stj

tawamkeag, Me, (O-yr.

Com., 1010, p.^n|

reeord).

^^M

Baco River, West Burton*

l,ft60

13.4

1900

tat An. Rep. f^M

Me (4-yr. reenrd).

Com,, 1910, p. 980.^

Kennvbec River, The Forks

l,fi70

11.7

1003

lilt An. Rep. M# ai

Me (lt>*yr. record).

Com,. 1010, p. 350.

Scioto River, Colunibtui, O, .

1,670

80.0

1913

Alvord and Bttrdick. i

Ppoob««^ot River, West

l.SSO

12.0

1903

Ut An, Rei», Me it

Bmnch. MilHnocket. Me,

Com , 1010, p 350 1

(lO-yr. record).

j^

AndroBCfiitgin River, Ruin-

2,090

2ft, 4

1895

Ut An. n»p i^H

ford FftlUi, Mo. (l»-yr

Com., tOlO, p.flH

r«cord).

M

Aroo9tock Riv«r, Fort Fiiir-

2,230

15.4

1007

lai An. Rep. |^H

Bfjld, Me. (8*yr. record).

Com, 1010, p,Sn!]

Kennebec River, Biotfham.

2,fUI0

U.7

lOOO

Ut An, Rep, Me.

Me. t4-yr. n»eord).

Com.. lOlo, p ;150 '

Kennebec River, No. Aii-

2,790

1.1,5

1007

Ut An, Rep, Me- (

Bon, Me. (7-yr. record).

Com-, 101t». p. 350- ,

And roar oiCRln River* Lewb*

2,050

22.1

1896

Ut An. Rep. Me. (

ton. Mc. (6l-yr. record/.
Kennebec River, Wntfli^

Com.. 1010. p, 350.

4.270

S5.7

1001

Ut. An, Rep, Me I

viUe, Me. tl8-yr. reoofd).

Com., lOio, p nnty

Hudeoii River, Mechatiiw-

4.500

25,2

1913

Hort/^n. I 7

viUc, N. v. (2<J-yr. record).

Wnathut !

St John Ri^'cr, FoK Keul.

5,280

14.3

1009

Ut. An, iitp Mfi

Mo, <0~yp. reecifd).

Com. 1010, p, .ViO.

Pennbut'ot River, We«t Eo-

0.000

H.C 1

1000

lit An. Rep, Ma.

field, Me. (tWyr. ree«rd).

Com. 10U», p. 8fiO

Penobscot River, B«n«or,

7,700

J6.0

1901 . Ut An. Hep. MagJ

Me, (lO-yr. fword).

' Com. u. 350. ^HI

■

Frequency of Flood m Streams.— An elaborate study €^H

^^^^^H (ntvgrnluije of flood f)uw» to [y^^ t^xpected in viirioiis pcric^H

^^^^^1 eoiitatned in VVc.stan K. Faiicr*8 piiprr on ^* Flood Flow^^|

^^^^^^H refened to. A(*coriiJng to 1* '^ 1^^|

^^^^^H occur iu a pcTiod of T V' <*^ M^H

rOBMULAS FOB ESTIMATING STORM-WATER FLOW 261

ft

08 log T times the average annual flocul. The rehitive magnitudes
of floodu which will probably occur in periaris of various durationa
'■ : io this relation, are shown in Table 78*

f :. Horton, in Bulletin Z of the U, S. Weather Bureau^ on The
rio.^ has explained the application of the iniithpmatical theory

nf pr. ...:.-, to the estimation of the probable recurrence of floods of
vaeiom magnitud<*3, and derived the formula

\ 80,000 /

^«r the Hudson River at Mechanics^^Ue, where the drainage area is 4500
«q. nukw. In this formula T - average |>eriod of recurrence in years and
V - Qiasdmum flood flow in cubic feet per second. In a discussion upon
FuIkr^M paper on ** Flood Rows** Horton also gives* the general formula

iFqm
V4021.5

(where 3/ <* drainage area in square miles) derived from 20-year
mmh of Neshaminy, Perkiomen and Tohickon Creeks, near
Philadelphia.

Itiortnation indicating the relative frequency of floods of various

niapitudcs on twenty-three American rivers are given by E, C.

Murphy in Water Supply and Irrigation Paper No, 102 of the U. S.

Ctoloigical Survey • The most significant information, compiled from

bi* records, ih given in TahU* 82,

Deai|;ii of Flood-water Channels. — One of the best studies of flood

• aiTge of Hircams is contained in the classic report on ** Prevention of

' K in the Valley of Stony Brook *^ (Boston)^ by James B. Francis,

' C. Clarke, and Clemens Her^^chel, This report wa,** mude in lH8fl,

tive flood in February of that year, when over 14tX)

ted. The total watershed of this brook was 13,92

•^ nnlw, and the storm from which the flood resulted inchided 5.80 in.

^ "tia; Buow and ice on the ground were ei?timated to correspond to

ti 2 In, mon*, making an equivalent of about 8 in. of rain in 3 dayti and

' ! r -in exhaustive study, t he engineern concluded that none of

! 11 riUilas discussed by them (the Dickens, Dredge, U'Counell,

'.'., Faiining, and BiirkU-Ziegler formulas) waa pertinent in thia case;

i^t a raUiTall of 12 in. in 24 hours was to be expected; that

II mm nnrt probable that this would run off at a rate greater than

' rate of prc»cipitation in that time, hut tlmt ultimately, when

'H>iAnu' .It^nticly bmlt up, the rate of run-off might reach 0,75

i[>itation. This, howc\xr^ would probably be so far

r50 of tlie rate of prticipitation represented aa large

I be given the flood chamiels.

. Juu « 1014, {). 125.

^ 262 AMERICAN SEWERAGE PRACTICE^^^^^

^^^^m Table 82.— Avbragb Interval Between Floods of Variops M^

TUDES IN 80MK AMERICAN RjVERS ■

River

Are* of
wnter-

•q. mi.

Length |
of ree-

atd.

yftir» i

Alaiimum
olMcrved

flood,
c.f .•. por
K}. mi.

Magnirudi! of flood aa eonqJ
%Q mmximixtn flood ^

0.6 to 1 0.7 to
1.0 1 1.0

o.g to ^M
io 1

Ay«mce Irequ^iiQy, ftmtl^

Kennebec . .

4,380

12

25.4

■ 2

4

12

Androscoggin..

2,320

12

23,8

4

6

12

Merriraac

Connecticut. . . ,

4,553
10/234

6©
105

18.0

20.0

15
12

Hudson

4,500

35

15.6

18

Genesee. .......

2,428

119

19-22

60

Passaio. . .

8,227

26

42.5

13

26

Hiiritan

806

96

64.5

24

48

Delaware. ......

6,855
24,030

120

37.1

40

Susquehanna,

17

28-30.6

6

9

Cape Fear

3,860

15

18-23

0 4

0 6

2

Savannah. . . . .

7,500

66

40

0 8

15

5 5

Alabama

15,400 ,

14

9.5

0 6

0.7

1 6

black Warrior...

4,900

17

32

0.4

0.5

0.9

Monongahela, . ,

5,430

20

38.1

5

10

20

Youghiagheny...

782

32

54-59

4

16

32

Allegheny

9,220 '

31

26 7

0 3

1

3

Ohio

23,800
15,700
28,067

22

16
11

20 8
3.3

1.2

2
4

3
2
6

10
3
6

llJinoia,

Rio Grande

Colorado

37,000

9

3 3

5

9

Arkansas. .

4,600 10

2 4

3

5 10 ■

^^^^H

Bear. .,

0,000 15

18

3

5 15 1

Another careful study of the design of a storm-water channel ■

^^^H tallied in the '* Special Report to the Commissioners of Sewer^

^^^^H Louisville upon the Improvement of Beargrass Creek," by J. M

^^^^B Breed and Harrison P. Eddy, in 1009. This stream drains a wnt^

^^^^H of 65.4 sq. miles, including the easterly portion of the city of Loufl

^^^^H A detailed study of existing data relating to fluwH of this strciifl

^^^^H the precipitation in Louisville was made, and compared with reca

^^^^H Hood flows of streams in the northeastern < ^^^^|

^^^^H Kuichling and Murphy formulas. It wai) ^ imIH

^^^^H formula gave too small resuitu for this locality, und tlmt proviitiotA

^^^H to he made for flood discharges amountbg to aborr '^t>^ ^> pizr^

^^^^B per square aiiie.

_ i

^^^^^B

CPIAPTER VUI

RATIONAL METHOD OF ESTIMATING STORM-WATER
RUN -OFF IN SEWER DESIGN

Few problems have afforded the sewer designer more miBgivinga than
the detennination of the quantity of storm water for which storm drains
w combined sewers should provide. The chief reason for this lies in
the fact that the problem is indeterminate, and that the information
which may be available and tlie formulas whi<*h may be used only serve
to aid hia judgment, upon the soundness of which the correctness of final
wlutioD very largely depends. In fact, it is a difficult ta^ik to say when
ion of HUch a i>roblem is correct within the usual meaning of the
tcause no two engineers acting independently would be likely
t<k reach the same conclusions as to the economic period in the future
upon which f o base the design of the system, the ultimate developmcut
wid im[irovcracnt of the district within this economic period, the rate
tiirtinfall for which the community can reasoiiahly be expected to pro-
lidu drainage, and the rate at which the storm water will reach the
•^en^ all considerations vitally affecting the siaes of the drains or

^ designed.
[*I t. attempts to solve this problem were based upon observa-

taotu or ratimatcH of flow in existing streams, gutters and drains. Formu-
la of an empirical character were derived from such studies, which
kftVd been quatc4 and described in the preceding chapter. Finally,
tk(^ att^'fition of engineers has been focused upon the fact tluit the run-off
tt din*(Ttly dependent upon the rate of rainfall and the rapidity with
»lii(ih the water will reach the drains. This is a long step in advance,
Iwt tlje problem is still (juite indeterminate and requires for its economic
•olution soimd judgment aided by experience and by all the information
'<■ obtained,

'^ Affecting Rate of Run -off. — TJie volume of storm water

W be carrd for by a sewer or drain depends upon the intensity and dura-

'-^ ihe rain, and the character, slope and area of the surface upon

' falln. Of the water falling upon the surface, a portion is lust

Hill another is required to fill the depressions of the

l>ortion sinks into the earth, where it is either retained

Iwy attraction or else percolates slowly through the earth to

" ffrounil water ami to reappear at some lower point in springs

263

u^

2G4

AMEUWAN SEWERAGE PHACTICE

or streams; another portion is absorbed by vegetation; while th<^
mainder flowB off over the Hurfaoe until cuUeeted in natural or artiiici
channels. This last portion is the one with which the problem of etor
drainage is concerned.

The proportion of the total rainfall which will flow off from any givi
area varies with the duration and intensity of the rain and with tt
amount of nioiHture in the earth before the storm, and also with the coj
dition of the surface of the ground^ whether frozen or covered with sno^
or ice. It w'dl also change from time to time on the Bame area as ill
character of the surface is artificially modified by the construction <
Btreeta, pavements^ and buildings.

It is evident that the run-off from any given area will be greatest,
when all parts of the area are contributing at the greatest possible rai
This requires a lapse of time, not only to allow the water flowing froi
the most distant part of the area to reach the outlet, but also to till de-
pressions and saturate the surface soil* The maximum nin-off is then
fore to be expected from a rainfall of maximum unifonn intensity lastij
BB long as the period of time required to allow the water from the farthi
point of the drainage area to reach the outlet; but on the other
the maximum flow during many stonns occurs when some portions
the district are contributing water at a much smaller rate tlian otb
portions, because of wide fluctuation in the intensity of the prccipitatii
upon different portions of the tributary area.

At the present time the so-called rational method of estimating t
amount of run-off is commonly employed in the design of storm-water
combined sewers. Even in St, Louis, the home of the McMath foi
mula, that formula has been displaced and the "rational niethod'*
now used in sewer design.

The rational method recognizes as axiomatic the direct relati
between the rainfall and the run-off, as shown by the formula Q = (*i
in which Q = the total amount of run-off from a given area in cubic fei
per second; C = a coefficient representing the ratio of run-off to rainfi
generally called the run-off coetficient or the coelficient of impcr\'ioi
uess; i = the intensity of rainfall in cubic feet per second per acre («
nearly enough, th»* r.-itr of minfMll iii inrlMS \ht luiiir"! : .1 = ilw ilrai;
area in acres.

In a computation i\v mis ukm ii*'»i, tim: nrr-f} a is uiMimTPly vunrnn
by measurement. It is also necensary to determine, first, the ^w>r
concentration, which is the length of time reciuired for the wat-
from the most distant point of the district to the neai'est sower u,. , -
thence through t he sewers to the point of observatitm; Beeotid, thegioit'
c^t uniform I r ' ' " * ' ;

at least, the l
design of sewers; and third, th- MiiJjmiiiit of nop*

STOHM^WATER RUN-OFF IN SEWER DESIGN

265

which depends upon the character of the soil, slope and char-
ier of Uw surface,
|Time Reqtiired for Water to Reach the Sewers (Inlet Time). — The

me tvquirtMi for flow over the surface and into the sower must either

N>tiinatcd from the available information or be determined by obtser-

lliOD, It will seldom be less than 3 or more than 10 minutes. In the

d *m&\\ districts, or fairly large districts with steep slopeSt thia

»i»frei|uently the most important element in determining the quan-

^ly of water for which to provide, W, W, Horner states {Eng. Ncws^

, 20, 1910) that he h^ reached the conclusion, based upon actual

vation.'<, that the water from the streets and sidewalks and roofa

ill mch the sewer in from 2 to 5 minutes, with street grades of from'l /2

!it , (improved streets), but that the velocity over graas plots is

fid even in heavy rains from 10 to 20 minutes will be required

i(w I be water to flow UK) ft. For the sake of safety a short time should

" aatunicd^ and allow^ancc made for lawns and grass plots by assuimng a

uttble coefBeieat of run-off,

Chiirl(*« H. (iregory, in his discussion of Gnmsky*a paper upon "The
mn System of San Francisco/' has computed theoretically {Tran^,
U See. C. E., vol, Ixv, p. 393) the rate of run-off in a gutter 1000 ft.
jwnf, hariDg a slop© of 0.0025, draining an impcnious street surface 24
. wulu, when tJicre is a uniform rainfall at the rate of 4 in. per hour, and
^that this rate of precipitation would have to continue for 42 niin-
> before tU« rate of discliarge would equal the rate of precipitation,
1 that 25 mmut^es would elapse before the rate of run-ofif equalled half
^fl rat« of precipitation. His conclusion is that for many roofs and a few
*t Kurfaces, where the Htorm-water inlets are moderately closely
ii,the common assumption of 5 minutes as the time required for the
iwntttr to reach the sewer at maximum rate may be true, but in
ttoit tmm thia time is materially greater, and that it varies widely under
' ' .'ices.

k of any definite information relating to individual

1 Ue fallowing information relating to the run-off from an

. :rr in a small city in Arkansas where the soil was heav>'

kc4, but without any paved or roof surfaces, is significant,

n wiis presented by James H, Fuertes in a discussion in

Engs., April, XHmK p. 170, He says:

•tmiil

l*Miror

n«fi Ih^ opportunity was presented of measuring the run-

hI in II southern t'ity. AUhou^^h the obser-

I inprovised ftj)parRtii« and tlie trrict of ground

r offers it with suitable apoltjgies fur its rutviger-

ity of publiwheil records of such informiition for

The tract of i^rourid sloix^d quit^ uniformly in

tsanjpr, the fall of thi^ surfwce being about 5 ft.

26^

AMERICAN SEWERAGE FRACTICB

in 100 ft. Along OQi* side a ditcEi was cut, into whleh the wMrr iimufl
from the whole urea. At the end of the ditch a ^niall weir wns •irT:ini;r4, ,
and the depth of the water flowing over the weir was measured wilh a t
ivory scale at as frequent Interv^als as the obaervatiotis ixiuld be rvwnii
varying from a minute to about 3 minute!;!. Tiie rain deptiis were iimilii
measured, though at less frequent intervals. The total depth of rain \
fell upon the tract, in the particular storra in question, was 1.3 in, wbiehj
in 37 minutes. The maximum rate of rainfall was 6 In. per hour, '^%
oontinuod about 5 mmutes and waa reached 11 minutes after the )
of the storm-

"At t!ie beginning of the storm the ground was very hard and dry,
tract was a hea\^, clayej^ soil, covered with a short and rather thin i
of grass. Fn»m the data obtained, it was deduced that 29 per cent, of <
total rainfall on the tract passe<l over the measuring weir; that i\u* avci
velocity of the water in the ditch was about 4 ft, per second; and th»ll
average velocity of the water flowing over the aurfaoe of the ground Ui\
ditch waa about 0.1 ft. per second."

The diagram accompanying this discussion shows that rain I
at 6.40, and run-off at the gaging poinlrat G.47; maximum rainfall nail
began at 6.51, and maximum rat« of run-off was attained at 6:59; (ram '
wliich it may be deduced that the time of concentration for lliis «
which would be the inlet time if this district were tributary to ^d^
sewer inlet, was about 8 minutes.

The rain continued at the maximum rate of 6.0 in, per hour for I
5 njinutes. The average rate of precipitation for il
gre4itei>t rainfail was about 5.3 in. per hour, and the i
was 7»2 cu. ft, per minute, equivalent to 2.18 cu* ft» pej- i<eeoud per s
or 41 per cent, of the rainfall rate for 8 minutes. The run*off fjirtur 1
therefore 0.4 L

Time of Concentration. — As defined above, the time of conre
is the time required for the w^ater to flow^ from the most dist
(mejisured in time) to the point under consideration. It h twmlf \
two parts, the inlet time and the time of flow in the sewers. Inlet t
has t>een di«eusi«ed in the preceding section. The time of flow mi
sowers is readily obtained by a simple hydraulic co?
conditions^ quantity of water and sixe and slope of »ew'_

It is important to distinguish the minimum time of conrentfttli{
from what may W called the actual tinje of coDcentTation. The fw
corn^sponds to the conditions for which .seiR-«irs should be dmf
conduits* full (or half full), and velocity substantially at a maximii
and conditions of surface such that run-off from roofs and greets i
flow in gutters will \h^ at maximum rates. Under these conditioof tl»
1 t on will b<^ a mimmuni ami "

i be a maximum. The cob

moitt serioua io which the sower may be subjeeted. The

STOHM-WATER RUN-OFF IN SEWER DESIGN

267

I of concentration is a constant for a given sewer ilistrict in a particu-

• slate of development*

On the other hand, the actual time of conceMtration rcpresenta the

linie reciuired for the concentration of the waters of a particular storm,

ander the conditions existing at the moment. If the storm is of moderate

ff the sewer may be but partly filled and the velocity of flow may

lore be considerably leas than the maximum. Moreover, unless

km hiitt prcA-iously been fidiing for some time^ the filling of depressions

nd the accumulation of sufficient head to cause flow over rough or

nearly flat surfacea will require an appreciable amount of time* The

toal time of concentration will therefore exceed the minimum in

[ill canea except tho^e for which the sew^er was designed.

In problems of sewer design the engineer is concerned only wHth tlic

minimum time of concentration; but when gagings of «torm- water flow

fire mode it is important to recognize that the conditions are reversed,

] WMi it is then the actual time of concentration which represent.^ the

j period of rainfall with which the resulting flow must be compared.

RUN-OFF FACTOR

The coefficient of run-off is very difficult of exact determination,
even for existing conditions, and is subject to great modification by arti-
kial alterations ui tlie conditions of the surface, such m changes in the
PXteiit of the built'-up district and in areas covered by paved streets. It
to Ibcrefore oece«8ar>' in designing sewers t^ estimate the conditiona
which arc likely to obtain a reai^onable time in the future, unless the
^y r . coniiiderati*>n has already reached such a degree of develop-

^ti • fvirtiicr changes are probable.

The run*ofif factor or coefficient, sometimes called the coefficient of
ttttperviouMiess, depends upon a large number of elements and is not
toortant for a given area, even during a single storm. It weis formerly
^'^lifldftn'-d that tfiia factor represented strictly the actual percentage of
Uiipi!niou» surface in tlie district under consideration, and that if the
tntire surface were covered with impendous materials, such as roofs and
Upf, I. TTients, the factor would be 1.00. More recently, however,

1^ ' ped tliat the factor is seldom unity, even for an aljsolutely

^': irfrtce. Some evaporation always takes place, even during

^^' . ^. of a rain storm, and even the most imperv^ious surfaces
*Wr|j iimiUl quant itie?4 of water. Irregularities of the surface aLno tend
' ^ ' " ^ack »ome of the water and prevent its running off a^ rapidly aa

h^m connection it may aid the engineer in forming a conception of

^ furihlem fjf run-off in consider the cjuantity of water actually falUng

I pi!riod« of time, as given in Table 83, computed from the

268

AMERICAN SEWERAGE PRACTICE

Table 83. — Quantity in Inches of- Rain Falling in the Specipied
Periods of Time at the Rates Indicated by Curve of Intensities,

Time, minutes

1 Rate of precipitation, inchos per
1 hour

Accumulated depth of precipi-
tation, inchet

5

6.71

0.66

10

4.75

0.79

15

3.88

0.97

20

3.36

1.12

30

2.75

1.38

45

2.24

1.68

60

1.94

1.94

90

1.58

2.37

120

1.37

2.74

Note that these periods of time are not necessarily measured from
the beginning of a storm, or even from the beginning of the downpour.
Prof. A. J. Henry of the U. S. Weather Bureau gives (in Bulletin D,
Rainfall of the United States, and also in Jour, West, Soc, Engs.f April,
1899) a table showing the percentage of cases of downpour in Washing-
ton, Savannah, and St. Louis, in which the maximum rate of precipi-
tation occurred at various periods after the beginning of the storm.
This information is given in Table 84.

Table 84. — Percentage op Cases in wmcH the Maximum Intensitt
OF Precipitation Occurred within Various Periods from the Be-
ginning OF the Storm

Minutes after

beginning of

storm

Per cent, of cases in whi(
Washington

:h maximum inien«ity occurred within period*^

Savannah

St. Louis

5

17

10

31

10

38

31

61

15

59

52

69

20

64

65

74

25

72

72

76

30

81

82

78

35

86

87

80

40

91

88

88

45

93

92

93

50

94

97

98

GO

100

100

100

\

The run-off factor gradually increases for some time after the bcgoc^
ning of a rain until the soil has been thoroughly saturated, and uar^
impervious surfaces have been thoroughly wetted and the d^JW*"*^'"'
filled. After that time the coefficient remains subit Bf '

STORM-WATER RUN-OFF IK SEWER DESfOS"

269

a given areft. It therefore makes considerable difference in the
aount of ruiHofT whether the critical precipitation comes near the

^ning of a storm or after rain has been falling for some tinie.

It hi also possible, as noted above, that if an excessiv^e ravn conies at a

Lt'mic when there is snow or ice upon the ground, the coefficient nmy

1 be sreater than unity, although this condition is so unHkely of occur-

t«ti« nliod to wjwer design that it may ordinarily be left out of

CO!, It.

In ihcir studicj* of rainfall and run-off, the Germans recognize three
dirtiDct coeflficientH, which together make up the run-off factor. The.se
coefiiclentjs are: 1, Coefficient of distribution of rainfall; 2, coefficient
jrott^titioii; 3, ctR^fhcieiit of retardation.

f^Goeffident of Distribution of Rainfall* — ^It is a well-recognized fact
tint heavy rains cover but a limited area, and the intensity of downpour
dimiitlHlw»s as the distance from the center of the storm increases.
Very little definite information is to be had regarding these matters,
flud that little hiLH not bei^n analyz-ed sufficiently to draw positive con-
flujiion*, other than that there k such a diminution in rate of rainfaU,
Auwficau engineers have usually been content to recognize the fact,
and to allow for it by using a smaller run-off factor for larger areas.

I'nihling states that according to observations in Breslau, Germany,
the rate of precipitation at a distance of 3(XK) meterH (10,000 ft.) from
the center of the storm was one-half the maximum rate, and that the
wdnetion in intensity was along a parabolic curve. From these data
tW fiirmula /) « 1 — 0.005 \/L (for L in meters) has been derived, assum-
ttig the center of the storm to l>e in the center of the drainage area.
D repnv»entw the ratio of the intennity of precipitation at a distance L
I (rtwn the center of the storm to that at the center. If L is expressed
fcfcet, this reduces to D = 1 - 0.0028 \/L. Upon this basin the intensity
wooiiH'* 0 at a diHtance of 7-1 /2 nule«^ from the center, or a storm may
w njjcclnd to cover an area 15 miles in diameter.

Coefficient of Retention. — ^This coefficient takes account of the water
r« f|Utrcii to wet the surfaces; evaporation during a storm ; water held back
in drpfiM^ions and irregularities of the surface, and by vegetation, etc,
*'' I'od by porous earth, which therefore doeg not find its

* vers. All of these infiuences have vastly more effect

^^ iiib ^/rginuing of a storm than after rain has been falling for some
'"*" nd itlxo vary with climatic conditions, so that the value of thia
tit iji far from constant, even for a single drainage are^. Further-
' wing cities the extent of the areas covered by roofs and

pavements is continually inereasing, with a corresponding
Uon of more ur \m& pervious areas, and pavementB and roofs are
' r and less al)sorl}ent. For this reason, present
iit lu-e of value only for comparative pm'poses. It

270

AMERICAN SEWERAGE PRACTICE

is usually necessary to chooae higher values in design^ to allow for growth
of the city.

According to Friihling, the values of tliis coefficient (assujmng the
surface obeady wetted by a previous rain) are about:

For metal, glazed tile aod slate roofs 0 96

For ordinary tile iind rfKifing papern. .......,,,,.,. 0 90

For aaphalt and other smooth and denee pavementa, , 0.85-0.90
For closely-jointed wood or stone block pavements.. - 0 84M) 85

For block pavements with wide joints. 0.50-0.70

For cobble atone pavements. , . 04-0.5

For maciidam roadways 0 25-0.45

For gravd roMclwiiya .0, 15-O,30

and fur largt* areiks^ there* may be ikswuuiiHl:

For tlie densely l>uilt center of the city . 0.7 -0.9

For densely built residence districts .0.5-0-7

For re.sidence districts^ not deaaoly built 0 2i;-0.5

For parkH and open spaces, , ...... 0.1-0,3

For lawns, gardens, meadows and cultivated areas,

varying with slope and character of soil . . ...... 0.05-0.25

For wooded iirca.s 0.01-0.20

Coefficient of Retardation. — If tlie duration of the atona causinj
flood coiuiitions i» lesii than the time required for wat-er to flow from tl
most distant point on the drainage area to the point for which compute
tions or gagings arc made, then the maximum di.schargc will come whe
less than the whole drainage area is contributing water. The ratio
the area so contributing to the total drainage area is called the coetficie
of retardation.

Obviously, if the precipitation continues at a uniform rate for
indefinite time, the greatest discharge will occur when all pari8 of tl
drainage area are contributing water, and at an intcr\'al after bcginnii)
of the downpour equal to the time required for water to flow from th
most di?^tant point (measured In time of flow) to the point utidfl
consideration. If the do\ynpour la*sts but a jshort time^ and particularij
if the drainage area \& irregular in shape, it is posKible tliat the ma.ximuB
discharge may occur when but a portion of the area is contributin
water* This portion will be the largest area within the drainage ar
and between two ** contours'' (lines of equal 'Hime-disiance** or equa
time of flow from the point under consideration) whose distance apar
measured in time, is equal to the duration of the downpour* If t hh tinij
should equal the time of concentration for the cntir- -"^t^" t^m.
would be unity and there would be no retardatiotu

In problems of i thec

of verj' large tlrtu i* '

STORM-WATER RUNOFF IN SEWER DESIGN

271

nun Uuding for a suMcieat period so that the entire area would con-
nbuia water — ^in other words, for a period equal to the time of eon-
Mnrtintion — and accordingly retardation should not be eon.sidered in
nieil work« The Germans, however, seem to work from a ditTerent view-
{ktermiaing first the maximura duration of heavy rain that is
to occur, and then the retardation coefficient, as well as the rate
pinfiill, corresponding to this period for the drainage area under
ideration.

American engineers have, very properly, neglected retardation
it should not be lost sight of in studying gagings of flow in
In other words, unle^ it is certain that the downpour has
for a period equal to or exceeding the time of concentration, it
be remenibered tlmt nil parts of the drainage area may not hii\'e
bocaetintributing water to the maximum discharge, and the area which
vii< Mutually eontributiag niU'^t be determined in order to find the true
ruo-off f!ic*tr>r.

'! thi« allowance for retardation^ the effect of the travel of

Kould not be lost sight of. Information on thta point is

not to be had, but would be required for a complete and accurate

rvrnluQ (jf ihc pfoblcm.

It mujit not be forgotten that the time of concentration for a given
ifa^iujpj area b not a constant, and will be greater in light storms when
tlk wwrm are but partly filled than in heavy storms when maximum
V€lt)citie» are attained,

condition, like the German ** coefficient of retardation/* is of
laeo only in studying gagings and comparing them with the
frU'rins producing the run-olT, since in sewer design allowance must be
ma^it? for maxijuum conditions.

Effect ot Storage in Sewers and upon Streets and other Surfaces. —
^*^till ur ftient of retardation is found in the necessity of filling

KitH *«w. , TH and other channels to a sufficient depth, and also to

uibite sufficient bead to carr>' away the water finding its way to the
Thu« it will be seen that a certain portion of the precipitation
»ch is finally running off is temporarily stored or retarded, and the
in the sewers is somewhat less than it would be if all the
d be conveycMi away as rapidly as it is received,
y has discussed this problem at length in Trans. Anu Soc. C. B.,
iV. V' 2*4>l, and, muking certain assumptions, has elaborated the
mKHtMi of dt*3sigriing storm- water drains with allowance for the
cif the conduits themselves. As a rule it is better in
to take no acxiount of tliis storage capacity, leaving it as
tor of safety. The effect of such storage must, however,
Mti wh- rs of storai-water flow and com-

STORM'WATEB RUNOFF IN SEWER DESIGN

II. N, Ogden pvcs a diagram, which is reproduced in Fig. 108,
e results of Kuichling's studies for the Gity of Rochester,

Lni is bancd on the assumption that the percentage of im-
ttreii in a given district bears a direct ratio to the density of
d&tioti, and that for similar general conditions districts ha\nng the
d^i^ity of population will have the same percentage of impervious
Mid the same run-off coefficient. Kuichling made a careful computa-
of ihe amount of different charaet^re of surface in the various
imge districts investigated by him, which Ogden has reduced to the

[0 10 20 30 40

Proportion of Rainfoll
_ Reaching 5ewe'S

fta. IOS.^Run-off dlfigmm based on Kuichling's studies. (Ogden.)

50

40

•

t

<30

t

J 20

4-

1

a.

n

/

/

r

/

r

/

/

50

I in Table "^ which contains the information from which Fig.
•'Wbeen prepared.

T*iu 88.— Relation or Density of Population to Amount op
l^lPliR\^ous Area. (Ogden)

PUvmbKr

t

l*9VTViil«C« of fiiUy imporvioua aurf)i««
Unimprovod
fltrofrit nnd
y&rdB

RodCi

sirevta

s 4 f
14 0
18 0
22 5
2R 0

3 3

7.0

10 2

U 7

It* 0

Tot»l pcrrneniaite of
fully irnpcmiouik «ut-

3.0

4 3
5.0
5.4

5 5

14.7
25.3
33.2
42 6

52 6

iliomr

these results are based upon detailed
I a comparison of two or three other

./ ?/?;

.^ » i..c-if -r:

ST^ -23 .4'

- HaU!^

1 -!a-

T..',- -irxr^

1

• r ■ i.i' !

■'/ J

, ill'

i;. Ml

0 'Mi»;

0 N)

I 37

(I

' !-. . 1 i..

.It

^P

101

0 OOM

0 do

1 l>3

Ml

\'.> 1! l.-nlf

"!•

'il

0 OO.V)

0 2o

0 4:3

1 '■

il.>irl> III

10

0 oo;;:j

0 15

0 26

1

1 n 1 nil '1

1 1. I'lM 1,

., . 1 ■'! I.I. 1

■ r.

,. . 1..
1 II • 'If

0

1 1 !«• r h'-f 1 ir<

f» 0

0 or,

I) <M^

■ 1- . .

1 .1 .

■A iiiif «i!T ill IJ
. • jiii ..ili-nt t'

lOUM.

» :i prc^cipitati

on of I.fiO k »^

STORM'WATBB RUNOFF IN SEWER BE^^IOH

275

In fprnertil, in the absence of suitable information from which to

I directly the run-oflT factor for a given area under conditions

|to exist at the end of the "e^nonomic period of de^ngn/* this

Htnay be most ^atisfaotorilv approximated by estimating the

livait;ot percentage of totally iraper\nouj3 area/' bs it is sornetirnos

Thu», if it is assuifie<i that in the future 15 per cent, uf tiie diwiru-t
%TtA will be covered by roofs for wliich the coefficient wou*d be 0.95;
» per cent, by pavements, with coefficient 0.90; 40 per cent, by lawns,
ith coefficient 0,15; 15 per cent, by gardens, with coefficient O.IO; y'
^ reiiulting coefficient for the entire district will be 0.4875 per cent.,
r, ID round numbers, 0.50.

APPLICATION OF THE RATIONAL METHOD TO DESIGN

inng decided upon the time to be allowetl for concentration of
water at the ftrst inlet, and upon the coefficient to be Uiicd, the
:it€wUj of rainfall is taken from the curve adopted for thiti locality
in detail in Chapter VI) and, since this corresponds almost
liy to the amount of the precipitation in cubic feet per second per
r,' the product CiA gives the amount of water to be provided for
•t the upper end of the sewer (first section). Having this quantity and
Ibr available ^ade, the sewer diameter and velocity can be determined.
OtiridhifE ^he distance to the next inlet by the velocity gives the in-
avoeat of time, i, to be added. The area above the second point of
^atninntion and corresponding to the new i is greater than the first;
^fc^ ielciixity of rainfall i ivill be less for the greater period of eoncen-
^'•tioii, and the value of C may be modified; but when these elements
fc^vt been determined, or a^^umed, the new value of Q can be obtained,
I {rom It the required Bixe of section*
1^ the use of diagrams tK\A method can be applied rapidly and
\ difficulty.

of the Use of the Rational Method.— One of the best ex-

o( the intelligent apphcation of the rational method of sewer

reported in ^engineering literature u found in the practice at

The foDowing fl/-*^nption of the apphcation of the methiMl

^^ptf:d and amplified from an article by W. W. Horner

%r« of .Sept. 21*, UHO,

) half Ht V Mf^it 111 tlift wemwr mhdSifmomm (a r«!Bidi»oe diatHct )

: fjTjfn thr nr4iti?r of the gtrwt to tJw oetiter

•H U ^ .,^ , * , , .inA f-^rm et'nlpr to cctiter of cron alJisrti,

t' • tout Mm fkf 3 ' ' Thi! ti«p€moy» portioit of liii«

i*** ii{}firffi%iau4*lr :

276 AMERICAN SEWERAGE PRACTICE ^

Per cent.
Sq. ft. of total

Streets 20,000 13.7

Alleys 6,500 4.5

Sidewalks 6,500 4.5

House roofs 27,500 18.9

Shed roofs 4,000 2.7

Yard walks 2,000 1.4

Total 66,500 45.7

"This makes a total of 1.53 acres. The percentage of the total area
which is entirely impervious will then be about 45 (the population for such
a block runs about 40 per acre).

''For rain of 10 minutes duration, it was assumed that 60 per cent, of the
water falling on impervious surfaces, and 20 per cent, of the water falling
on lawns and hard ground, would run off. This gives an average of 38
per cent, run-off for the whole block.

''The following table (Table 88) gives the assumed percentages for each
dass, and the final average value of C in round numbers:"

Table 88. — Assumed Percentages op Run-off for Illustration of
Rational Method

Duration t in
minutes

Per cent, run-off from

Coefficient C

Impervious portion ■ Pervious portion

10

60 20

0.40

15

70 30

0.50

20

80 35

0.55

30

85 40

0.60

60

95 50

0.70

120

95 60

0.75

These percentages of run-off are based upon the assumption that the
critical rainfall or downpour of the assumed duration occurs at the be-
ginning of a storm, before the surface has been thoroughly wetted. This
is not alwa^-s true, particularly for the shorter periods, and a somewhat
safer basis, in many cases at least, would be to make no reduction in the
coefficient for the shorter times of concentration.

Having decided upon the run-off coi^fficient or series of coefficients
appropriate to the location under consiiioration, and the proper rainfall
curv^e to be used as a basis of de-sign (Horner's rainfall curve for St. Louis
has already been shown in Fig. 93), it is convenient to construct a
curve showing the product Ci for any f>eriod of concentration. This
curve gives directly the discharge in cubic feet per second per acre
for the duration of downpour, but applies only to the average residence

STORM-WATER RUNOFF IN SEWER DESIGN

277

district for which the percentages were derived. For this case, the ctin^e

wuuUl he iiis fihowu in Fig. 1 10.

It will be noted that, for this case, with the coefficients selected as
aboy«, A uniform rate of run-off equivalent to 2.20 cu. ft. per second
acre is used for all time* of concentration up to 15 minutes, and
Ring rates for longer times. Of course the selection of a rainfall
cur%-e and of suitable coefficients can only be made by one who is
with the locality and its records of precipitation.
sumiQi; tliat all streets and alleys are open and that no rights of
Wmy are required^ the actual coraputa.tions can be taken up* The
firiit reriuisite is an accurate plat similar to Fig. Ill; on tliis should
be entered the elevations of the proposed or established street and alley

I*- as

i ^ 0 10 20 30 40 SO 60 70 60 90 100 llO 120 130 140 150 160

Time of Concentration ( t)
In MInutca,

Flo. 110. — Rate of runoff for St. Louis residence districta.

P><lt9 and, if no contour map has been made^ the existing surface eleva-
twins ulniM also lie shown. The street and alley inlets are then located
oij Uic plat» placed on the upper side at all street intersections and at
*ll low points b<*twcen streets, provided that the interval so established
mjft, t?xc4?ed 600 or 700 ft. When the inlets have been ** spotted,"
R'^Xt step is to lay out the sewers to reach them, and at the same
titDfj t<i m!!wor ah the private lots in the district. Obviously, the most
! layout is one which follows the natural surface slojies in
line* toward the dutlet of the district, but also concentrates
How a<f rapidly as possible. This can usually be done in more than
'^ny, and it is oft>cn necessary to make partial desigui^ and conipara-
Minuites to determine which is the cheaper.
Witli ' ' 1 ^ iifid «ewers loeated and the present surface elevations
*"* ^11 lid alleys known, it is a comparatively easy matter to

^^^hi\f*. the iiTTti tributary to the sewer* at any point under existing
iiom. This, however, is rarely of great importance in determining
•ftAWinuni nin-off, as the district is usually only partly built up and
and the f run-off will be small; also much of the

wat«jf w:ii vater courses without reaching the sewers*

^

A

^

278

AMERICAN SEWERAGE PRACTICE

It is necessary for the designer to stop at this point and imagine tl
district as it will be when completely settled and paved. Observatic
of the nearest settled districts and a knowledge of the probable trer
of real estate activity will enable him to estimate what class of proper!
it will be when improved; that is, what class of houses will be built ao
what amount of grading may be expected in shaping up the lots. .
study of the original surface and of the probable class of improvemem
will permit the construction of a set of minor ridge lines which wi
divide the small areas draining into streets from those draining into tl:
alleys; and by these the final areas tributary to each inlet can be show
on the plat and the acreage computed. Fig. Ill shows such a ma]
and in Table 89 are given the drainage district numbers and the arc
of each district, the sum of the areas being checked against the toti
computed as a whole. These areas are based on an assumed conditio
of final grading.

Table 89. — Drainage Areas Corresponding to Sewer Map shown

BY Fig. 111.

Area No.

Ares in acres

Area No. .

Area in acres

56

2.52

97

1.13

57

1.86

98

1.59

58

1.13

99

2.39

69

2.76

107

0.33 1

60

1.73

108

4.48 .

61

0.88

108-il

. 1.45

62

1.78

109

11.15

63

2.12

110

1.91

87

1.47

180

0.87

89

2.11

182

0.24

89-A

0.32

183

1.12

90

0.20

184

3.35

91

1.63

185

0.55

91-.4

1.10

186

0.62

92

2.66

187

0.75

96

1.63

188

1.38

Total = 5<

).21 acres.

The preliminar>' sewer grades should first be drawn in at the
depth, beginning at the lower end, as the elevation at the c
approximately fixed by outside conditions. Then, beginning
upper end, the final grades can be established at the same time i
sizes arc determined.

It is supposed now that the location of all inlets and the a)
and approximate grade of the sewer have been decided upon,
the areas tributary to the sewer have been computed. Ther
to be determined the amount of run-oflf and the size of 8CW€

STORM-WATER RUN-OFF IN SEWER DESIGN 279

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IF*

h- r* IS 0

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Pi

d

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d Pt d d

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d d r^ d d

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+ §S +

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SS22S

282

AMERICAN SEWERAGE PRACtWE

other hiilf has already beeo accounted for by mchjiliiig: district 187 in I
drainage area A.) Roof water is then computed from 720 -h 70 -f 275
106,5 ft.; 10»>5 X O.0O133 = 1.42. 1.42 + 1*63 == 3.05 ^ A\
The other values are then found as shown in the tabula tion.

4. M. H. 16*5 to 165. Drainage district Xo. 63, through inlet near
M. fL 1G6. ^\lt hough some of the roofs in this area ha%'e already been in-
cluded as draining into sewer between M. H, 175 and 165, it must be remem-
bered that we are designing for future conditions. Very likely many
of the roofs allowed for are not yet built. So no deduction is made fn
area No. 03, even though we have already allowed in the oomput-ations tli^
some of the rain falling upon it drains elsewhere* Then A = A' — 2.\
and for iS = L50 we have from diagram, d = 12, it = 5,3, t — 0.4 minut

5. M, H. 165 to 154. Area above 165 = districts 61, 63 and 18
Area - l.tV3 + 2.12 - 3.75 - A,

In view of the fact tli.yt rrnifa on Alleott Ave. ara expected to drain
sewer between M. H. 176 and 165, while half of the area of the correspond
lots is already included in districts 61, 1H7, and 63, assume thai half the ro
water in district 62 (length 770 ft.) reaches the sewer above M. H» 16
(This assumption has already been made in computations 2 and 3 J

770 X 1/2 X 0.00133 -^ 0.51 acre. A* =- 3.75 -f 0.51 = 4.26. Tlien '
= 9,39 and from diagram, if 5 = 1.50, rf = 18 in., v = 7.2, and i
mimite.

6. AL II, f64 to 163. Area A - that in computation 5 plus distrid
62 and 60 which drain into c^tchhasins near M. H. 164. Therefore
= 3.75 -f 1.73 -f 1-78 = 7.26. No further allowance for roof water
to be made, so ^1' = A, Then Q = 15:97, and for S * 3.00, d ^ 1%
tr « 10.1, f - 0.3.

7. M. H. 172 to 173. Area A = district 58 = tl3 acres. Xothifl
additional for roof water. Therefore ^4' = .^1. 5 = 0.50; then from dl
gram, we obtain the figures tabula tod.

8. M. H. 173 to 174. .\rea A - district No. 58 only - M3. For ro
allow

1/2 of 85 ft. for section of Allcott Ave. opposite

district .58 = 42.5 ft.
1/2 of 275 ft. for section of Allcott Ave. opjMjhiie

district 186 ^^^ 137.5 fl,
1/2 of 75 ft. for section of Davison Ave. opjMisite

district 186 and east of district 58 - 37.5 fl.
All i>f 275 ft. for roof wuti^r fron» distrirt \RPx = 275.0 fU

402.5 ft.

rf * 16 in., B

i:

492.5 at 0,00133 acre = 0.66 acre. Then .4 '
Then Q = 2.20 X 179 - 3.94. and for S - 0.50,
I = 2.0 minutes,

9. M H. 174 to 163. A = that of computation 8 -h diwlrict 186 d
Ifig into M. H. 174, making 1.13 H- 0.52 = L7fi acres. liuof w»t4?r m
Iwj allowM for

STORM-WATER HUN-OFF IN SEWER DESION

2B3

410 ft. on Ailcott Ave. below distriafc 186 \
410 ft. on Dnvisoti Avo. below district 58 j

1/2 of 75 ft. on D»vi«ori Ave, below distntrt 58

1/2 of 5MJ0 ft, an iUloott Ave. nppmite

diatfiets 58 and 186 - IHtJ fr

= 820 ft.
- 37 ft.

1037 ft.

[0 00133 X 1037 *L38. A* * 1.75 -h 1.38 = 3.13; then Q - 0.89 and

r S • .10, rf = 12 in,, V == 7.6, t = 53 seconds = 0,9 minute.

[M M. H. 163 to 102. A = district 59 -f district 107 -f areas above

H 174 Mid 164. ,4 = 2.76 + 0.33 + 1.75 (cnnnp. 9) -f 7.25 (cornp. 6)

I UlOarrc^, No additiunal roof areas. Then Q = 2.20 X 12.10 ^ 20.64,

f& « LO, from diagram, d = 2i in., r = 7.3, t = 27 seconds = 0.4

I^M. n. 1132 to 161. A = siimi5 as m comp. 10 -f district 56 +
182, both these districts draining to catchbasins near M. H. 162.
|i ^ 12.10 ^- 2.52 H- 0.24 « 14.8<i. No additional roof water
Therelorts .4' = ,i. Then Q ^ 2.20 x 14.86 - 32.70. Then if
1.00, d « 2.7 in., t> = 8.0, t = 16 seconds == 0.3 minute.
[12. M. H. 171 to 170. .4 = district 57, to catohbasina near M. H.
iL A m im. No additional roof area. Therefore, A' ^ A, Then Q
s6 = 4 m iind for *S =^ 1,5. d = 12 in,, v = 5.3, / ^ 23 seconds
e, .'VssiinTne time of concentnition at eatchbasin = 8 nunut^s.
[ i*i" M. H, 170 to 169* No additional surface area, therefore, A = 1.86
lh«/orr. Itoofs on the half-lots on Beacon Ave., opposite district 57, and
I ilir whnW lot« in districts 55 and 56 between district 57 and M. H- 169
I If allowed fur, 1 2 X 280 + 210 -f- 210 - 560 ft. 560 X 0.00133 -
^' ^ .4 -f 0.75 ^ 1.86 -f 0.75 ^ 2.61 acres. Then Q ^ 2.20 X
W »lu7$, and far S = 0.75, r/ = 15 in., v == 4.3, / = 119 .sccjmhIs = 2.0

[N. M. H. 160 to I6l« No additional surface draina(?e admitted, there-

,4 * 1,86 ti8 above. For roofs, allow same us in cj^jmp. 13 plus roofs

I rtitlf?i«, full iota, frtmi M. 11. 169 to .street next to right or 2 X 280

ft. 560 X n.CK)133 - 0.75. Then A' ^ 2,61 (from comp. 13)

ZM, Q = 2,20 X 3.30 = 7.40. For S = 2.00, d » 15 in., p

1 7^ I • 12 ncconds ^ 0.7 minute.

14 M. H. 161 to 160. Draimige area = everj'tlung above M. H. 161
Cffti oomp. 11) * 14.86 acrt's; (from conjp. 11) 1.86 acn^s; no nciditional
^«ffftm tma: then A - 14,86 H- 1 8t» = 16,72 acrc^. For roofs, wlu»lfT Int^
>f newer between M. ii. 161 and 160, or 2 X 435 « 870 ff
-70 « M6 acres. 16.72 -f 1.16 == 17. -SH ftcres,
dnmo^ there may bo roof w.nter from lot» f^icinu Beacon Ave,, ahntg
?&5, A» allow*fl for in comi)Uttttion H, amounting to 0.84 acre in
'tmm district 55 draine into another branch of the system, ihia
of 0.81 acfT' ts not inchidpd in any addilionH of surface area
j_^nii m«>»i be addrd in nil o?itimatc8 of A* along the n»ain line (re-
■Ite bHow M. U. 161),

^^

284

AMERICAN SEWERAGE PRACTICE

Then A' = 17.88 + 0.84 - 18.72 acres, 0 = 2M X 19.72 = 4L:
li S ^ 3.25, d « 24 in., v = 13, / = 33 seconds = 0.6 minute.

16. M- II. IfiO to 159. No additional surfnee area; therefore, j4 = 1ft J2
Fur roofs, include the same as in computation 15 + allowanw for both aidM
of the section 160-159, or 2 X 415 = 830 ft. 0.00133 X 830 « 1.11 acm.
Then A' = 18 J2 + 1.11 = 19.83, Q - 2.20 X 19.83 -= 43,0, and for S
= 2.5, d = 27 in., v = 12.3, t « 34 seconds = 0.6 minute.

17. M. H. 131 to 194. No surfaoe area draining into M. H. 131, the
A = 0* Roof 8 must he allowed for on both sides and for the whole di«
2 X 310 = 620 ft. 0.00133 X 620 = 0.82 acre. Then Q = 2.20 X 0.1
1.88, and if S ^ 2.0, ri == 12 in., v = 6.1, f = 51 seconds ^ 0.8
No surface water inlet, and storm water received only from roofs, whtd
very quick; assume 5 minutes from time rain falls until it reaches isen

18. M. H. 194 to 197, Surface water from district 183 admitto
M. H, 194; therefore, A = district 183 « 1.12 acres. Roof water from SM'
ft. on south side and also from half of 420 ft, (outside of distTict 183). On
north side there will be roof water from ti50 ft. In all, 650 + 210 -f 380
- 1240 ft. 0.0O133 X 1240 = 1.65 acres. L12 + 1.65 = 2.77 acres ^ v*'.

0 = 2.20 X 2.77 = 6.1 and for 6* = 0.60, d = 18in.,(i = 4.4, t = lUseooiuli
= 1.9 minutes,

19. M. IL 107 to 257, No additional surface water inlets, the
A - 1.12 as before. No additional roof inlets, therefore^ A' ^ i
before. Then Q =6.10 as before, and for S = 2.0, d « 12 in,, r

1 « 22 seconds ^ 0.4 minute.

20. M. H. 257 to 159. Drainage area is increased by districts 1841
185, through inlets near M. H. 257. 1.12 + 3.35 -|- 0.55 « 5.02ftcjt» « -4."
Add for roof water from 1/2 of the lots fronting Allcott Ave. in ilisfriclj
1/2 X 800 X 0.00133 = 0.53 acre. This must be included in all suo
ing designs until district 172 has been included. Then A' - 5.02 + Oi
5.55. Then Q = 2.20 X 5.55 = 12.20, and for 5 « 5.00, d ^ 15 in.,
11.8, ^ - 14 seconds - 0.2 minute.

21. M. H. 159 to pinnt a. Drainage area — everything above
159, plus district 108 (inlet near M. H. 159). 16.72 above 161, ph
« (district 108), plus 5.02 ftbove 257 = 26.22 acres == A.

For roof water, add the sections outside the direct drainage area
above, 0.84 4- 0.53 ~ 1.37 acres. Also add roof water from district \\
0.00133 X 360 = 0.48 acre making total roof albwanoe 1.85 acr«tt,
.4' « 26.22 + 1.S5 = 2S.07 acres. Q = 2.20 X 28.07 * 61.8, and]
S =» 2.00, d = 26 X 39 in.^ v = 12.4» i ^ 15 s*'conds = 0.3 minute.

22. M. H. 168 to 107. Areas 108vl and H9.i, inlets near M. H.
0 32 plus 1.45 - 1.77 acres = A, For roof water, inlets from one «ido^
440 X 0.00133 =» 0.59 acre, (Note that house inlets indicate
from only one side.) 1.77 + 0.59 - 2,36 acres « /I'. Q * 2,20

^ 5.20 c.f.s., for S - 4.75. d » 12 in., v » 9.6, t ^ 46 seoaub
minute. Assume time of concentration at inlets = 7 nnnutea,

23. M. H. 167 to point o. Area .4 = as in (22) -f distriota SOi
(This aa»*ume^ the wholi* of dr.«trict 108 drnini' i Hj
nJibougb the whuU of it baa previously been *

STOHM'WATBH RUN4)FF IN SEW EH DESJQN

285

In poasible, although usually each inlet would receive part of
.) Then .4 = 1.77 + 2. 11 4- 4.48 = 8.36 acres. No additional
|«r, therefore, .4' ^ A, Then Q ^ 2.20 X 8.36 = 18.4 ami for S

d ^ 12 in., V is beyond limits of diagram and t is negligible.

rom point a to M, H, 157. Area includes district 90, through inlet

ii'ttsi corner of Beacon and 1 heck la Aves. Then A ^ (8,3*3 +

0.20 ^ 34 J«) - (district las ec»unted twice = 4.48) = 30.30 acres.

wati*r add the constant items shown above, amounting to L37

I in tx>mputation 21;alsufor sides of the section of sewer under fson-

u 2 X 400 X 0.00133 = LOG acres. Then A' = 30.30 -f 1 37 -h

I2ja, Then Q = 2.20 X 32.73 = 72.0, and for S - 2,56. d -

9 in., V ^ 13.5, ^ = 30 «€»oonda = 0.5 minute.

torn M. H. 157 to point b (catchbasin inlets). No additional surface

ined^ llierefore, A ^ 30.30 aa before. A' is same as in computation

llowiince for 225 both aides, between 157 and b, 0.00133 X 2 X

||i50 acre. Then A' = 32.73 + 0.60 * 33.33. Then Q » 2.20 X

73,3 and for S ^ 1.50, d == 30 X 45 in., i? = 11,8, / « 19 aeoonda

inutf.

rucu point b to point c. Drainage area «^ the total above M. H,
ich is 30.30) + districts 92 and 109, with inlets at point 6. The

Krtrict UJ9 IB included here» although in ordinary times a part, and
the whole, would be admitted at M. H. 273 and 275. Then A
%&S -h ILlo ^ 44.11. K<Mjf water is fu!!y allowed for by the
i of diistricts 92 and 109, except the sections outside the drainage
notrd above, amounting to 1.37 acres. Then A' = 44.11 + 137
Q = 45.48 X 2.20 - ICX). For S = 1.0, <i - 34 X 51 in., v =
21 seoonda — 0.3 niinutc.
•am M- H, 274 to 275. No surface inlets; therefore .4 = 0, Roof
ua one side of the sewer, 405 ft. long, 0.00133 X 4a5 = 0.54 acre
11i«i Q « 2.20 X 0.54 = 1.19, and for S = 1.5, d -= 12 in.,

« 77 aeooods - 1.3 minutes.
'om M. II. 275 t^ 270. Esliniate that surface water from 3 acres
ct ICKJ will enter at M. H. 275, in addition to allowance for roof
hich will bo tliat in computation 27 and allowance for one side, 400
ti^tn M. H. 275 and 270, 0.54 acre. Tlicn total roof allowance =
IB, and v4' * 4.08. Thrn 0 = 2,20 X 4.08 - 8.98 and for»S « 0.8,
r » 6.2, I = 84 fteconds = 1.4 minutes.
M, H. 365 to 270. No roofs. Then Q = 2,20 X 0.87 « 1.95
S m 2.0, d *= 12 in,, e ^ 6.2, i ^ 27 seconds = 0.4 minute.
Ifl con trail y located in district, therefore assume time of con-
3 minutea.

M. il. 276 to 270. No gurfaoc water. For roofs, both sidei
133 X 840 - 1.12 acres. <? « 1.12 X 2,20 = 2.46, For S -
\n.t i» = 4 9, t ^ 8<i seconds = 1.4 minutes. Assume tune
ration 3 minutes as it i^^ wholly on roofs.

M II. 270 to 269. Area, distrint 180 and diatriot 109 (a»-

dfiiji llirougli M, H, 274, 275, and 270), Then .1 - 11.15 -h

I \.\.. njofs, we have the alkiwanoea in computiition 30.

^Mfa

286 AMERICAN SEWERAGE PRACTICE

Then A' = 12.02 + 1.12 = 13.14. Then Q = 2.20 X 13.14 = 28.9
for S — 6.0, d =^ 18 in., y = 14.5, t == 9 seconds = 0,1 minute.

32. From M. H. 269 to point c. Area = that above M. H. 27(
district 110, A = 12.02 + 1.91 = 13.93 acres. For roofs, only the par
the line 276 - 270 lying without district 110 has to be added. 2 X 20(
400ft. (for both sides) 400 X 0.00133 = 0.43 acre. Then A' = 13.9i
0.43 = 14.36, Q = 2.20 X 14.36 = 31.6, d = 18 in., » = 20, ( = negligi

33. From point c to M. H. 155. Area above 6, 44.11, plus area above 5
13.93 = 58.04; deduct for district 109 included twice, 11.15, leaves 46.«
A. No roofs in this section, but the areas noted above must be indud
amounting to 1.37 acres. Then A' = 46.89 + 137 = 48.26 acres. Q
2.18S 48.26 = 105. For S = 1.0, d = 36 X 54 in., r = 10.8, t =
seconds == 0.2 minute.

34. From M. H. 271 to 272. No surface area. Roofs from one Bid(
400 ft. 400 X 0.00133 = 0.53 acre = A'. For 5 - 2.5, v = 7.0, d -
in.f t = 400/7 = 57 seconds = 1.0 minute. Time of concentration tal
as 5 minutes from roofs only.

35. From M. H. 272 to 155. The direct drainage area is district No. 1
A = 1.38. Roof water is to be t^ken (or allowed for ) on one side of t
section of sewer; 0.00133 X 400 = 0.56 acre. A' = 1.38 + 0.53 = 1.
Q = 2.20 X 1.71 = 3.76, and for S = 4.75, d = 12 in., v = 9.5 and t =
seconds = 0.8 minute.

36. From M. H. 273 to 277. No surface drainage. Roofs both side
entire length = 2 X 310 X 0.00133 = 0.82 acre. Then A' = 0.82. Q
2.20 X 0.82 = 1.81. For S = 1.50, d = 12 in., v = 5.3, < = 59 aeooi
= 1.0 minute.

37. From M. H. 277 to 155. District 99 drains mainly to catchba
near M. H. 155, but partly to M. H. 277; for safety, assume entire drain
at M. H. 277. 71icn A = district 99 = 2.39 acres. For roofs we havei
the half-lots in district 98 minus a length of about 400 ft.; making 2O0
0.00133 = 0.27 acre. Then A' = 2.39 -f 0.27 = 2.66. Then ,0 =2
X 2.66 = 5.85. For S = 1.00, (/ = 15 in., v = 5.2, t == 29 seconds =
minute.

38. M. H. 155 to point d. Drainage area = everything to M. H.
= 46.89 + districts (91 + 188 + 99), 46.89 + 1.63 + 1.38 + 2.39 =- 52
acres = A. For roofs there is allowance for the half lots in computat
37, besides the sections permanently brought forward in main line, C
-h 1.37 = 1.64 acres additional; also roof areas draining to the section
sewer between AI. H. 276 and 270, without district 110, amounting to C
arre as in computation 32. Then A' = 52.29 -|- 1.64 +0.43 =54.
Q - 2.10 X 54.36 = 117 c.f.s. Then for S = 1.0, rf = 36 X 54 in., t
10.8, / = 14 seconds = 0.2 minute.

39. From point d to M. II. 154. Arvii A is increased by districts 87 i
9l.\, tlierofore A = 52.29 + 1.47 + 1.10 = 54.86. Total roof allowa
for parts of districts outside those discharging into this branch throi
surface irdets, as in (•()mi)utati()n ."^S, = 1.37 -f 0.43 = 1.80 acres. At
tional roof water from the half lots included in computation 38, 0.27 a

» Total olapsod time i.n such that Ci \a ]€<-* than 2.20.

STORAUWATER RUN-OFF IN SEWER DESIGN

287

i from one eido of the sewer from d to 154, 130 X 0.00133 ^ 0.17 Acn^,

I Aim tA> be included. Then A' = 54.8^ -h LSO + 0,27 + 0,17 - 57.10.

|Tlwa Q = 57,10 X 2,14 - 122. a»d for S - 1,0, ^ - 36 X 54 in. (the ex-

»i U Twjiarly enough to call for the next size) ; v = 10.8^ t - 16 seconds

' 0,^ niinttte.

10. From M. IT, 154 to point e. No increase in area A. Increase in
M ftlluwajitje fur 140 ft, of sewer, one side, 140 X 0.00133 = 0,19 acre,
A' - 57 JO (from computation 39) + 0.19 = 57.29. Then Q =
113X57,29 - 122 of a. For S = 1.0, d - 3<i X 54 in., v - 10,8,
13 «*fxjnds = 0.2 minute;.

41. From point e lo M. 11. 153, Drainage area inrreasod l>y districts
rami 98, ixnd A ^ 54.86 + 1.13 -f 1.59 = 57.58. For roofi* add 1.80, as

riously notiHl; also allowances for one-half of one side along 4(X) ft. of
If WW = 0.27 for half Iota in district 96, and for roofs in the aj-e^

Upooile the futis of districts 96 and 97-125 ft., 0.16 acrt*8. Then A' =
pia 4- 0.27 4- U.IO -f 1.80 = 59.81 acres. Then Q ^ 2.12 X 59.81 -= 127,

iid far tS* = l.O, </ = 36 X 54 in, (nearly to next larger size), v — 10.8,
[ * 2S >j(»oonds = 0.5 minute.

42. Fr»»m M H 153 to main sewer at M, H. 136* Area increasfd by

,4 = 57.58 H- l.t)3 = 59,21. For roofs add the outside
I- before, also allowanw for lots cast of district 8 94,96
nil K7 = 250 ft. 250 X 0.0tJl33 = 0.33. Then .4' = 59.21 -f 1.80 +
P>3i« « ttl.31 and 0 = 2.11 X 61.34 = 129. For 5 - 1.0, d = 36 X 54
» i ■• 10«8, ( " 15 seoonds = 0.3 minute.

Another Application of the Rational Method.— Substantiftlly the »ame

JUicthml, w*ith only minor di (Terences in the inanner in which it is'de-

>ek)[»ed, ij* followed in tlie PuIjHc Works De|)artuiont of Hoston. The

[iwiloiring descripti*)n of the procedure has been prepared by F, A,

pjoy, assihtant engineer, to whom, and to E. S, Dorr, engineer

the Sewer Service, aeknowledp;inenta are due for information and

luniishcd and for permission to make free use of them.

ay out line of main drain above point where sled is required to

DO upper end of area, determining roughly the principal hydraulic

liota with lengths between, and location of the most important

i iMect a number of points on the main drain where the velocity of

'-^ !. i<L.ify iQ change ctjnsiderably, either from change in the hydraulio

r from increase in trihutiiry area from entrance of large branches.

' - • irsi •!* pointM in their order over the columns on the Schedule (page

«'<) bfftnninK with the highest.

ii* Hehcdule in order from top to bottom,

)H the ♦'Htitnated time required for the storm water to

ttii rooUf gutters, etc. FWq to fifteen minutes is

nni 18 to be added to the estimated tinic of flow in

tirikiiii ut give loUtl trme used in calculating rain intensity (/?♦).

. Funj)ii)ii I f / I ^ rK.- nf ruintfil] in inches per hour^ or cubic feet p<*r

Mi

tfl

288

AMERICAN SEWERAGE PRACTICE

second per acre. For Mr. Dorr's curve, /?, * 150/ (i + 30) in whii
equals total tinie in minutes before mentioned.

1 1

i i
- •§

o > z

1

^

h

Ui

Ui

"

-

-

=-

=

-

-

-

-

=

Z o *> u

• § ¥ •

1 555

B

s

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=

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=

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I

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lil

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cr

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a

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a

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es

The total tributary arra is determined just above and just below t
points selected and i)laced at head of columns.

290

A Af ERIC AM SEWERAGE PRACTICE

k:50

120
LIO

«.oo

■o

i 70

E.50

^.40

.30

10

-i^

^

6a'

., 1

^^^

/.

u

/ '

— «^

-?:*:■.

Z.

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7

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=22

— '

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:-::

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::::

:.v.

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-4^'

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^^^^^

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— ■

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-36-^

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fc?<t^S/^ t^'^ -Sv'.^W!-^

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^^

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^

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x>'

-rr

J^

rr-;

....

—

iE-

i

0 I

3 4

5 & 7 6 9 to II IE 1^ 14 15 \b 17 i6 19 20 €

: ; Velocity, in f*-. per sc&»J ? i ! I : i >

0 to 20 30 40 50 60 70 IQ 30 100 ItO 120 lio 140 ISO m 110 1(0 190 W
Q ^ Copacity , in cu.fr. per sec

Fig. 112.^ — Approximate curves for B<?wer dcdigOi St. Louis,

STORM-WATER RUN-OFF IN SEWER DESIGN

289

1^

The fffc^rtive area id the total fxibutary arra multiplied by the peroontago

iff expected. This may be estimated by dividinjyf the area into im-

lun juid pfn*iotia portions, taking say 100 per cent, of the impervious

tiir of roofs, asphalt 8f reels, pa%'ed yards^ ete,, and adding a

l! tttgp of the pervious areii according to judgiuent; say 15 per

mtkl lawns and 30 or 40 per cent, for dirt, etc. The dope of the

maiu' I'l also be considered.

TTiffj percent age of imper\'iouauesa of the total tributary area is found by

f.j.i,v.r- tMtM thrtf the iniper\'ioU8 portions of the various types of area es-

ve, and dividing the sum by the total area. A further oorreo-

nnng upon the time of contribution, may then be applied. This

1 Is based on tlie theory that both the percentage of absorption

r faces, and the pc»rcentage of storage on the Impervious

t nt the beginning of a storm and that the percentage of

f s with the duration of the storm. More obser\^a-

rmine this factor projK-rly. Adiagram ha s^ however ,

dtvtgned to use for this correction until such observations are made.

'Tgth of drnifi is taken from the point next above to the one under

limit ion*

,\iiffmii(*d r** at up'per end, in case of the first upp<*r section, is taken

Ibe \t'lodty of flosv in feet per second in a 10 fir 124n. pipe at the de-

fiiiulic grade. In other cases it m the same a^ the velocity

t of the priL'Vious section.

* I ■' di lower end is first rotigldy taken from a sewer diagram based

Kulter'* formula, Fig 11*1, by sefting scale on proper h3'draulic grade and

Bepimg at probable discharge. The calculation is then finished und with

» ilinchnrgi^ found, u new V at outlet is more carefully calculated. This

hi to 1m» repi^ated if necessary until the proper V is found,

'Mean I"* is the averagf of the V at upper and lower entla.

i_^ t J r length of drain , ^

kTtme in drain «= ^ ,. _ ^a ^ nimutes.

I mean V X iK)

|Talal tiniG ** sum of times in nuiins to point tiikt*n -f time allowanoe.

I rate deti*rmined V»y formula.

[UitflbftrBe " eubio ftn^t per second ^ Ri X effective orea.

[For ttfiproximate estiinatoti by this method, for areaa not exceeding

) acrcs^ Lovejcij* has devised t he very ingenious diagram illustratnd in

|. il3« Afl Hhown ill the illuHtration, an elToctive area of 6 acrea might

of 1 4-1 / 1 cu. ft. per second in a district w^bere the mean

I id a 28-in. skewer flowing full would be required to care

Xhm ruij-oti.

IMPAIUSON OF DESIGNS BY THE RATIONAL METHOD AND
BY McMATH FORMULA

Since Ale Math's fornmla was derived from ob«orvations made in St.

' ' " for use in that city, it becomes particularly

' the results obtained by the appbcatiou o(

292

AMERICAN SEWERAGE PRACTICE

Table 9L — Comparison of Rational Method of Skt
WITH McMath Fobmula, for St. Louis Conditionb.— ((!

Mftximum cUschnrge
in cu. ft. per Mjcond

Bcrlweeo
man-

By ration-
til mt^tbod

By Mo-

Math
formula

DlA

ine

i:il-194
194-197

197-257
257-159

159^

108^167
167-(j
a- 157
157-6

b-€
274-275
27,5^270
365-270
276-270

270-260

269-c

f-155

271-272

272-155

273-277

277-155

155-<i

fi-l54

154-ef

e-153

153-136

28.07
2.36
8.36

32.73
33.33

13,14

14.36

48,26

0.53

1.71

0.82

2.66
54.36
57.10
57.29
59 71
61 34

43.6

39.0

2.60

1.88

3.05

2.00

6,10

8.00

0.60

6,10

8.00

2.00 !

12.20

13.9

5,00

6L8

51.3

2.00

5.20

7.03

4.75

18.4

19.4

29.30

72.0

58.3

2,56

73.3

59,0

1.50

100.0

75.8

1.00

1 19

2.17

1.50

8.98

10 9

0.80

1.95

3.19

2.00

2.46

3.89 ,

1.26

28,9

27.9 1

6.00

31 6

30,0

16.70

105.0

79.5

1 00

1 19

2.14

2 50

3,76

6,45

4,75

1.81

3,05

1.50

5-85

7.75

1.00

117.0

87.5

1.00

122.0

91.0

1.00

122.0

91.5

1.00

127.0

94,5

1.00

129,0

97 0

[ 00

* tDcludfia roof WBter rc&chms suwrrw. ' By Fitf. 112*

It is interesting to note that in this comparison the difft
resulting size of sewer is comparatively inHiKnifieant.
follow* howevori that this would be the case in of her com pari*
would depend upon the judgment exercised in selecting coefj
ticularly in the application of the rational method.

ADDITIVE METHOD OF COMPUTING RUW-

Thi)* mothtKi, devrloped by Carl U. Xordell {fCn(fin4i
March 11, VM^) mid uo^ ia t])« di^gn of i»torm«wiit43r i

294

AMERICAN SEWERAGE PRACTICE

drainage areas of 200 to 300 acres, and that the intensity of pre<'hat!iliinj'
for a 20-minute period is about 2.50.

Cincinnati. — The rational method is employed, with tna
rainfall curve, % = l^/i *•*. The coefficients of run-off uaed var>* f^t
0.2 to 0.9, according to the assumed development of the territory at
the end of a period of 40 yearg.

Cleveland.— Robert Hoffman, Chief Eng., Department of Publi((
Scr\icc, states that present practice in Cleveland is to first: coniputc ibe '
time required for water to reach varioas points in the system, and thrn
from curves based upon intensity of rainfall, read directly the q\mii-j
tity of water to be cared for. The curve for total run-off (coefficient^
C = 1) ia

. _ 5040 _ J^Jl.

^ " * "^ P + 1440 *''' ^ '^ r + 1440

Other curves are drawn, corresponding to C «= 0.5 at thebegitming
of the storm and 0.7 after 1 hour; 0.4 at the beginning and O.G after I
hour; and 0.3 at the beginning and 0.55 after 1 hour. Their cquatiom ^
are:

4158_

^ ^ t» + 3960

4200 _ 3780

^ ^ f » + 2400' ^ ^ (' + 2700'

Of the first curve, that for intensity or rate of run*off per acre wheal
C = LO, HotTmau says: **\Viih the exceptions of a few stomw, Ib^j
rain rate curve amply providos for such storms as occur in thi« »»h> j
tion," It has been taken as a reasonable ba^^ia for design. By inter-
polating between the curvt^s given, such coefficient of run-off may be j
employed as the judgment dictates. It should not bo f- i that

modification of tlie rainfall curve by applying a varia. >eiit

assumes that the greatest intensity is at the beginning of the 8lonii,|
and that the intensity decreases regularly as the storm progresscis.

Louisville.— Quantities of atorm water are estimated by means of tii«|
McMath formula, using a rainfall rate of 2,25 and run-off *:
varying from 0.4 to 1 and even more. The slope, S, Is t
per 1000 where the district is very flat and is increased proportion$t«l3
in steeper districts in the eastern part of the city.

Newark, N. J.— The Hering formula is used, aasumlng i » L5> <
the following values for C; suburban areas, I; w©ll-devclopetl ta^^^wT
L25; comph^tfly developed areas^ L50.

Ifew York City, Borough of tiie Bronx. — The same method
fimployetl a^ in the Borough of lUchmond. For inteniiity of pnn^ipitJ
tion tlie formula used is i = 120 (f + 30) and C is t^ken aa betw«'<
0J4 and 0.75.

New York CitXi Borotigh of Brooklyn.— McMath's formulA in i
aaauming a maxinmm rate of rainfall of 3 in. per hour for 30 mmttt*
C ia taken IxHween 0.50 and 0.75.

Fork City, Manhattan Borough. — The quantities of storm water

hiAUnl by tlu* Heririg formula^

is taken as 1.02 for suburban districts; L39 for well -de vol oped
itricts* and LG4 for cornplotoly buiJt-up areas. The corresponding

rn of r are from O.oU to 0,S0,
Itw York City, Borough of Queens. — The additive method is em-
loaned. The rainfall cun^e employed is shown by the equation

^ " i(i + 4.14)

id thifl b assumed to follow a 10-niinute rainfall at the rate of 3 in, per
»ur. C is assumed between 0.30 and 0.81.

Hew York City» Borough of Richmond,— Quantities are estimated
rom the funuulu Q - CIA,

The minf&tl equation i = 105/(1 + 25) is used and this precipita-
ion ia aasumed to follow a 5-minule rain at the rate of 3.5 in. per hour.
iff Uikim as ranging l>etween 0.30 and 0.S2. i

tew Orleans. — Itun*uff eurven baaiid on the Biirkli-Ziegler formula
I used- Maximum rainfall rate of (3 in. per hour for short periods is
naitumed, and the following run-off factors; for densely built-up areas,
« 0.80; for medium conditions, C = 0.60; for sparsely built districts
» 0,50; for rural conditions C = 0.20.

Vtwtudeer, R. L— .Sewers designed ai>out 1S85 by the Burkli-Z teller

I formula, v^'iiii 2-iu. rate of rainfall^ have in many cas(?i3 proved too small

I The ration;d formula is now used, having a rainfall curve constructed

from local observations^ and taking the rate of precipitation correspond-

iag to ti i>t*riod of 8 minutes plus onfshalf the time of flow in sewer.

Tho c()i?fhcient ts varied to suit the conditions in the judgment of

l^w' t^ngiueer.

Providence. — City Engineer Otis F. Clapp states in a letter to the
^tikn that the oniinar>* combined sewers of Providence are tle^igned
^ cun* for 0,5 in. of rain per hour and as a usual thing have proved
•^itsfoctoiy. Storm-water drains proper, however, are designed to
'^^ve from 0.75 to 2 in. per hour, according to location and conditions.
St lottis. — The rational metht>d is employed, as explained in detail
^^t^ in thin cliapter. For intensity of precipitation the etpiation
' • (Sfi/O + 0,5)1"'*' is employed, and values of C ranging from 0.20
**»0y5 ^|.^* tu«c*d, deponrling upon the character of the surface.
^^ : r, Mass.— The Btirkli-Ziegler formula is employed, asing
.,f of about ] in. (varj'irjg aomewbat with size of area and
*^^^' •!* imjface)p mnd coefficient ranging from 0.02 to 0 Jo.

29G

AMERICAN SEWERAGE PRACTICE

FOR HOW SEVERE STORMS SHOULD STORM DRAINS

DESIGNED

From an economic point of view, it ia possible to compute appro3l
mately the point beyond which it is more economical to allow overflowil
and to pay or suffer the damages rather than to increase the size
storm- water drains, if it ia possible to estimate satisfactorily the damag
which may result from flooding, and If information is available to
dicato the relative frequency of storma of various degrees of Beverit(

Practically, however, such computatiooB are of little significant
Local circumstances and conditions, physical and financial, have usual!
a controlling effect upon the extent to which such drains can be dc^igne
to care for extreme maximum rainfalla. The legal responsibility
the community is also an important eonaideration, although it shou
not be controlling, since any damage from overflowing must !)e sufTem
by members of the community, if not by the entire community iLa|
municipality.

The responsibility of a city for damages of this kind ia genera
held to depend upon the character of the storm, and the courts Jiai
held that '*raiiif alls are differentiated for judicial purposes into ordinar>%
extraordinary and unprecedented classes. Ordinary rain storma
those which fretiuently occur, extraordinary storms are those which ma
be reasonably anticipated once in a while, and unprecedenWtl ator
are those exceeding any of which a reliable record is extant. Th
usual rule in determining the resporisibility of a city was stated man
years ago by the New York Court of ApjKjals, 32 N. Y» 489^ as foUov
*If the city provides drains and gutters of sufficient siaGO to
off in safety the ordinary rainfall, or the ordinary flow of aurfa
water, occasioned by the storms which are liable to occur in tfc
climate and country, it is all the law should require.*" (Eng, Re
June S, 1912).

The question of what constitutes ^'ordinary" storms still rema
Are storma which may reasonably be expected to occur on an avtira
once in 10 years ordinary or extraordinary^? There fwx^nis to Iw
way of satisfactorily answering this question, and it will be ne
for the engineer to decide in each case what is the w^asonablc rondttid
to be met. The abstracts of legal decif*ion» quoted upon the foDowilf
pages may be of assistance in guiding the judgment, pn
respect to the legal rcsponsibilirv of m inunirii^jditv f'»r r
iuadet]uate storm* water aewer

Generally mn< ^ - * - f ^.j,,, ^f,,. n,»a*iirin

main or trunk Kt of » brnrv^h drnin; yi

the darnngt

STOHM^WATEIi HUN-OFF IN SEWER DESIGN

297

icularly if storm relief overflows can be provided. Moreover,

il b a much aimplor and Uj^ually a hm expensive operation to reinforce

dupiicatc a main sewer than to rebuild many small laterals. The

iioual eoBt of constructing the latter of ample size when first built

uttl Ri^ncrally be inconsiderable, while the a<iditionaI cost of a main

newer large euough to care for the most severe 8torm.s may be prohibitive,

pftrticularty if it la to be dei^igned to meet future conditions!, which may

■" iit for many years to come. It is therefore generally advisable

i-i brunch or lateral aewera of the caimcity which wll ultimately

mired, giving the mains and submains a capacity sufficient for

,. -ill conditions and to provide for the growth for some years, i^^th

ihc expoctatioa tliat new relief sewers will ultimately be required to

QKTc adjcquately for the entire run-off from the district*

ABSTRACTS OF LEGAL DECISIONS RELATING TO FLOODING
OF SEWERS

(Taken from "American Digeet, Municipal Corporations")

Alabima, 1902. — A trity for the efficiency of its sewers is bound to make
jirovi^ioa for such floods ixs may be reasonably ejtpected front previoua
occiirremim, though at irregular and wide intervals of time* (Arndt V9,
City of Cullman; 31 Ho. 478; 132 Ala., 540.)

Belaware, 1888, ^In an action for damages to property from an over*

fcw of a BGfwer during a severe storm caiLsed^ as alleged, by the inauf-

$ci«iiicy of thf» aewer and an obstruction in it, it is for the jur^^ to de-

^^tnam whether the injury was caused by the insufficiency of the

•WW or any obstruction in it owing to the neglect of the city, or by the

'ttiM;iiitudo of the «tonu, discharging a gre4iter quantity of water than

f^nfiiit rcfwoual>ly be expected from past experience^ (Harrigan vs,

<^-'ty of WilminKton; 8 iloust,, 140; 12 Atl, 779.)

I^^UwarCi 1893.— A city ia not liable for damages caused by back-

I a 3*fnver caused by an excessive and phenomenal rainfall

iJch tht^ city could not reasonably be bound to provide.

iiamm v4. City of \Mlmington; 40 A 740.)

Ikliware, 1898.— The testimony of an engineer as to the neceaaary
I dpicity irf m Hoiv'cr in a particular locaUty for ordinary occasions, is
of what is an extraordinary rainfall. (Ueflsion vs. City
; 27 Atl, 830.)
^^^m, 1697,— Where a city has provided sewers or drains of ample
'' ' >(i all water likely to fall or accumulate up<m the

'vy (KU'aMons, it is not guilty of negligence in failure
•id pmvnio for unanticipated and extraordinary storms*
r- Adams*; 72 111., App. 602.)

^i^Hrita

298

AMERICAN SEWERAGE PRACTICE

Ulinois, 1901.-^A munidpal corporation must see to it that th^t
of its sewers ia of jiiiiple capaoity to carr>' off all the wator likely toUai
itt hut it ia not liable for damages caused by an extraordinaiy and
excessive rainfall, (City of Chicago vs. Rustin; 99 III., App. 47.)

Iowa, 1896. — The fact that a city has notice that drains cociainidcd
by it to carry off street surface water are insufficient, fails to uap ordinwy
diligence to make such changes aa appear reasonably neceeaarf to mikt
the drains serve the purpose^ intended, does not render the city IbM ' "
the resulting overflow of private property where it did not aei
the flow of the water, or collect the same and discharge it <v
property otherwise than it would naturally have been di&r
thereon, and it was not negligent eitlier in devising or in adopt i
plans of the drains, (Knostman <fe Petersen Fumittu^ CcK w. tuy <a
Davenport; 99 Iowa 589.)

Kentuckyi 1881. — A municipal corporation is responsible for <lamttg»
caused by the want of due care and skill in constructing a sewer, a«d4>Uo
for the insufficient size or capacity thereof. (City of Covingfoo ***
Glemion; 2 Ky* Law Rep., 215.)

Massachusetts, 1903. — Where, in an action against a city for daom^
arising from water coming on plaintiff's premiaea through a city snrw,
there was no evidence that the sewers were defective in eonstnicft'^' •
obstruct ihI or out of repair and nothing to show that they wen
linhed otherwino than by persons acting as public oflieeR!* ntu
statute, and the procjf tended to show that the defect, if any,
sewers was in the system which failed to carry off imniediaidy ft |
accumulation of water due to a heavy rainfall, plaintiff could
recover. (Manning tfs. City of Springfield, 184 Mass., 245.)

Minnesota, 1897. — A city which, in grading a street, construrtt'dl
embankment across a stream, making a culvert for the water to j
through, cannot be held liable for damtige caused by the in^ufti««
of such culvert to cariy^ off tlie water during an imusuul stonu, tin
such insuf!iciency resulted from a failure to use ordinary care orukili^
its construction. It was not required to anticipate such storms a« (f<
the history of the countr>^ would not reasonably be expected ta o<
and if it employed competent engineers who were justifiofl in bdi^
and did believe that the culvert was of sufficient size, it was not n0
(Taubert r.s. City of St. Paul, Minn.; 08 Minn,, 519; 71 X. W.,*

Missouri, 1894.— ^ Where the negligence of a city in failing to ke«jf^
sewc»rs opc»n coritrtl^uted to the damage to property, it is liable aJlh
the r£4in causing the damage wits of an extraordinarj* charactiir, (Wo«
t',f. City of Kansas; 58 Mo. A pp. 272.)

Missouri, 1901, — Where a city set up the defense that iht br«)sij
of a sewer was caused by the act of God manifested in an imu
rainfall , and there was no evidence that the sewer was def eeti\nr by i

Ai^^

i^i

STORM-WATER RUN-OFF IN SEWER DESIGN

299

imprupor coDBtructJou and failure to repair, and that the rainfall
\ (if till unuamil c har f icier. It waa proper to charge that if an unusual
iufall would have caused the breaking of the sewer notwithstanding
dttft^t*t thtm the city was not chargeable with negUgenne^ but if the
dng was caused by such defects or if it was caused by such defects
iiglod and concurring with unustial rainfall then the city was
Me. (Braah vtt. City of St. Louis; 161 Mo-, 433.)
ICissotiri, 1903. — When? a rainstorm such as had never o<*curred be-
bro, eauaed a flo(Kling of the lands from a sewer, no greater than would
Ave occurred under natural conditions, the sewer having been scientific-
[tuilt according to the best judgment of the engineers and having a
&nt capacity under ordinary conditions, the injurj' results from an
of (Iml, for which the city is not liable. (Gulath vtf. City of St*
Duis, 179 Mo., as,)

New York, 1861. — There is something very like a contract to be
tiplicd from the construction of a sewer at the expense of the adjacent
rkperty, that it may be used to drain the property thu.v* charged with
ccni Hi ruction, arid it would seenx that the adjacent property holders
ive a right to ojjen drains into it; and in a suit by such adjacent property
►Idiir who had opened his drain into the sewer upon his own respousi-
Lity and whose premises had been flowed by backwater through the
uu in a fre«liet, it was held that a verdict giving him damages must be
(Barton vs. City of iSyracuse, N. Y*; 37 Barb. 292 affirmed
36 X. Y., 54,)

Hem York.— A sower in the city of Troy, built by the owners of land

l^lfiiich it passeii and l>y the city where it passed through its

alleys, passed through the premises of plaintiff and emptieil

Bto the Hudson river. Another sewer built by the city was connected

riUi it. One T. pf*titioned the common council for leave to enlarge

opening between the sewers. This was referred to a conimitlee

pj»a<r<!r* The city commissioner, whose duty it waa to look afler

spect sewers, authorizt^d the change to be made. In doing tho

tT, built a wall across the sewer first mentioned, partially obstruct"

ttheout' * 1 diminishing the capacity of the sewer^ by reason wherc-

(U baeaj . 1 tiud fdled up and a storm occurring the accumulated

f%ftter buint opi*n the stnver upon plaintiff's premises, causing

*^iiiiUMp^ T, present^td his bill for the work to the common council,

^di waa audited and paid. Held, that the city was chargeable with

I iMJticG tif the obstruction and was liable for the damages resulting there*

I 'f»im. (Nims r*f. City of Troy; 59 N, W, mi)

Rew York, 1902,— Where a municipality has constructed and main-
^ l«iie»l a 8**wer adcnjuate for all ordinary purposf*s it is not Uablo for
I ^ttrioi to ttbutting owners, caused by overflow of the sower due to a

300

AMERICAN SEWERAGE PRACTICE

storm of extraorrlinary violence, (Sundheimer tw. City of New Yc
79 N. Y. S., 278; 77 App, Div. 53, reversed 19030

Pennsylvania! 1802, — In an action against a municipal corporati^
for damages for iiijuriea sustained by the bursting of a sew^r, owiagl
its negligent construction by defendant, when it appeared that ovrtaie t«
an extraordinar>^ flood the breakage would have happened even if the
negligt^nce complained of had not existed, no damages can bo rocovercd
(Bolster vs. City of Pittaburgh; Leg, J 204.)

Petmsylvania» 1002. ^The mere omission of municipal authoritl
to provide ade<iuate mains to carry ojf the water which storms and tlw
natural formation of the ground throw on city lots and stn^^ " ^

sustain an action by an owner of land, against the munh
damages arising from the accumulation of water, (Cooper v«. City d
Scranton; 21 Pa. 8uj>or. Ct. 17.)

Texas, 18^— Where a lot owner knows that his premises will be
flooded in case of a heavn^r rain, unleas a certain city i"
street adjacent thereto is cleaned out^ and give^ no notit '
no effort to remedy the defect, he cannot recover of the city, dnmjij
caused by flooding his premises during such storm* (Parker ri.
of Laredo; 9 Tex, Civ. App. 221; 28 8. W., 1048,)

West Virginia, 1896. — A city is not bound to furnish drains or i
to relieve a lot of its surface water. (Jordan va. City of Ben«
W- Va.;42W. Va., 312.)

CONCLUSION

While the problem of detennining the quantity of atonn watef^
be carried by drains is still difficult and indeterminate, much adv
has been made during recent years in the methods of attacking it-
has been due largely to the securing of accurate rec '
showing duration and intensity. More ijiformation sh'» J J

run-off from rains of known intensity upon areas carefully sindJ^U
determine their local characteristics (similar to that given in tiie i
chapter), and observations of the time recjuired for the water ta i
the sewers, is very much needed, particularly to assist the eng
making a judicious selection of the coefficient of run^off. Then
need for detailed and long-continued studies of the distributiun oil
fall within areas of comparatively small extent, say up to 5 squaw mJM
in order to furni.*jh definite information relating to tho area c!<)vcn>l°
heavy storms, and the rate of diminution of intensity of precip
as the distance from the center increases. The older empiricnl fa
are gradually giving way to rational methods of eomputatimi,
enable the engineer to exercise hia judgment more rettdily sad *
structures peculiarly adapted to local conditions.

a^tmm

CHAPTER IX
GAGING STORM-WATER FLOW IN SEWERS

^ of gaging the flow in sewers have been referred to in Chapter

leosuremeuts of Water. Aa a general rule, weirs, current

pother moasuring dovicea are impossible of employment in gag-

Jowa, and recourse must bo had to computation of the dis-

observations of the depth in the sewers, and from the

jmetLsurod slope and known or assumed conditions, such as

affocting the flow,
fiis are likely to occur at any time, and observers cannot be

Iy on duty, automatic recording gagos for showing the depth of
k any moment are practiciilly indispensable. At least two of
poceasfuy, in order to determine tlie slope of the water surface,
Hrequently very different from the slope of the sewer. In
k> the depth gages, it m desirable to have a number of maximum
which siiow the greatest depth of sewage at the point of
since the last observation, but give no further infonnation.
f several kinds of automatic recording gages for sliowing the
l>f the sewage or water level at a gaging point, bat all of them
> one or the other of two general types, float gages and pneumatic
Recorders of either type are also applicable to weirs
antinuous record of the head upon the weir is desirable, or
when an autographic record of the elevation of a water
[j*Dquiro<L

in Chapter VI, upon Precipitation, it is extremely important

automatic gage should have a good clock movement, tliat

regulated to keep correct time, and synchronized with the

nil * '■ lie records of which may be studied jointly.

i with dials the regulation and synclironizing

[gmatly simplified, but few of the gages now on the market

[dials* It may well be questioned whether electrical operati<m

on hirge works where several gages are employed would

ble, as it certainly would be desirable.

FLOAT GAGES

-J of thia t>T)e, a float contained in a pipe or other suitable
riueh thi? sewage stands at the same height as in the sewer,
301

302

AMERICAN SEWERAGE FRACTWE

is connectod with a recording apparatus through the medi
rh:iin. tape, or by a stifT rod or tube.

The Hydro-chronograph. — This is made by the Hydro M
Co, of Philadelphiii^ and consi^jt^^ of a float and a recortier, Fig* 1 1
float is connecte*i by a chain with a sprocket wheel at the record
motion of the float b thus transmitted, on a reduced scale,
moving iu front of a vertical recording drum, which is rotated
weekly, or daily, aa deaireti. The diameter of the cylinder is au"
time scale of about 1 in. per hour may be employed.

The amount of reduction in vertical scale uall depend upon thi
of motion of the float. Thia company manufactures a weir j

IH. — The Hydro-^jbronograph

which the fluctuations of water level are recorded without rec
but this can be employe<i only for a range of about 2 ft. F<
sewers it is impracticable to use a dnmn long enough to cover tt
of elevation Hithout reduction. The list prices of these inst]
range from $100 to about $200.

Friez*s Automatic Water Stage Register. — Tliis instrumml
by Julit-n V, Vnez of Baltimore. As shown in Fig. 115
iflo'tt ntiti-if-v till* ifrtMM ^*!k Tdt iit«« wliiji^ the pen in ^Tins^H"! fii

QAOING STORM-WATER FLOW IN SEWERS

303

tathtf iiacb of the drtiin, by meima of clockwork. The clock is jjroxnded
' with A did and h&ndSi which faeiUtatea greatly the proper regulation of
I Uif timepit*c«*.

Tlu* nhndcr is -S in, long and 12 in. in circumference. The clock can

I lit afranfi;e<i to drive the pen the leng:th of the cyh'oder once a week

|or onw a liay. In the hitter case, the time scale would be 1/3 m. to the

our, and this is the largest scale for which the instrument is regularly

^*G. 115. — Friez improved automatic w at or-
st.igr regis tor,

^^f*^ 8pr« icket wheeU are provided for different ranges in height of
^Vt» JIM fallows:

»o««^t.r *«trTlrvcl j of chart \ Sc«Je of height*

5 ft.

Ill ft.

IS ft.

_ ^« ft.

I ft.

1 It. '

1 ft.

I ft.

1 ft.

I ft. lo 1 ft,
U.2 ft. to 1 ft.
0 1 ft. to 1 ft.
0.0667 ft, to 1 ft.
0 05 ft. to 1 ft.

^prtiri of Ihitm iufllrumenU rim«e from $115 to |160.

Gliders Iron Foundry Water Level Recorder. — ^lu this gage the cord

II urm currying a pen in front of a circular chart,

i. work, Fig, 1 16. The pen accordingly uiovet* in a

, and the tune-scale varies with tlu* (irjcjition of the jxm. The

•- »'f»cltw«c*d in a east-iron box njounted upon a hollow standi

304 AMERICAN SEWERAGE PRACTICE

ard through which the float cord passes. It Is made In two d20fl> hi
8-in. and 12.-m. dials, and the prices are $75 and $90, respectivi
they can \m obtaine*:! with an iron outer door for $5 additional.

Obviously, \^nth this gage, the scale of heights as recordeti upol
chart will doiiend upon the range to be covered and the site
chart. A rectangular chart h not necessarj' for records of this kindj
the oiJy disadvantage of this form of record is that the time-scaJe i
duly small when the pen is in its lowest pasition.

Fia. 116. — Water-level recorder (Builders Iron Foundry).

Builders Iron Foundry has also in some cases constructed a mc
tion of the recording instnunent of the Venturi meter for Ui«r» wi
float, to indicate and record directly the rate of flow over a weir J
also to integrate these rates and show on a recorder the total qu
parsed.

Stevens Continuous Water-stage Recorder.— In thia liu«1
the pencil h moved h v by a belt cntitrullod by a whii»l

which a cord frorn n <*s. TIj*' ri^'tm! is iiin<h* \i\

soQtal cylinder ar
reeled off from ai. u inn n in po,v-iL

W AGING STORM-WATER FLOW IN .SEWERS

305

beets of paper and keep contmuous records for long periods

ithout r€»newing the record sliret. A niechanisra is also

which the raotion of the pencil carriage Is reversed after

lie limit of its motion in one direction, and in this way it is

record an unlimited range in elevation without reduction

^■arly constructed, the cylinder of the Stevens gage is driven
wRtf and it is claimed that with this method of operation the
C can Uq left from one to two months without attention, and
■plain cases records
^m have been made
^ptentJOQ to the in-
RF It is also con-
ykh a spring for
cylinder, but in
is ncccssarj^ to
ug about once in

truinentd are
cupold & Voelpel
Ore. The list
iie weight-driven
55t, incuding copper
uunte47misef and one
eupply of paper^ k
The botie of the in-
li measures 10 X 12

ter is 8 in. high, and the total weight, including float and
aliout 65 lb., par^ked for shipment.
matic Pressure Gages, — In those gages a diaphragm box or
timber is innneriied in the liquid, and the charigcj* in pressure
t*m the rising or falling surface are transmitted tlirough a
&tic tube to a recording apparatus located at any con-
at.

bows an instrument of the diaphragm type. It is made for

[or 12-iu, charts, and the priccH range from S55 to S80, int-lud-

conuficting tubing* Thi^e instruments are made by the

[Imirument Co* of Foxboro, Masa., and by The Bristol

Watorbur>% Conn.

Flow Recorder^ Fig. 118^ made by the American Steam

' inufactiu^ingCn,, Baston, maybe placed in a manhole,

-r in a near-by building. One-fourth inch copper

twHJti* from th«* recTonler to the inlet at the sewer where la

fDompcnaator/' which is a special form of diving-bell. It

117. — Diaphragm pressure gage.

^^■ia

306

AMERICAN SEWERAGE PRACTICE

rcscmblca a piece of tubing, 1-1/2 in, in diamoter var>nng in ieng
from a few inches for small sowers to 3 ft. for 20-ft. sewers; it is |
slanting, on an angle of 45 deg. with the vertical, in the directioo
flow, and extends to within a few inches of the bottom of the
This conijiensator i.s const rue tt*fi smooth outside and inside so th
sewage is not apt to collect. The inlet is at the verj* butt nut. Cb
made for this deWce are^ that no float is required, no diapljrngm at I
inlet» the pressure medium is air and will not freeze, and the

Fia. 1 18. — Sanborn flow recorder.

may be placed in any convenient location. The price complcUf i
compensator and 25 ft. of tulnng, is S75.

Other Gages* — For very accurate detenninations of water kv^
float or pressurr* gages are not applicablr on account of friction int
moving parts, back-la^h of mechunical partju, etc. On arcount '
capilhirity, ordinar>* staff gagrs instTtrd directly in the water,
having scales marked on them with «cros set at s«>me dctcrmiw
elevation, are also uncertain. An improvement on the ordinary
gage consists in the use of a phunb l>ob suspendiHi by a fine wire, whi^
paasQs over a wlieel at the end of an arm held horisoiilally ovtf I

GAOISQ STORM-WATER FLOW IN SEWERS

307

vftter* By a suitable scale marked dd the horizontal ami, readings are
oUttiiMHl by lowering the plumb bob until it just touches the water.
When the detomii nations have to be made in dark or inaccessible
piftC0»T »o that the point of the bob cannot be seen, an electrical contact
nmy ho brought into usot In this arrangement one pole of a battery is
cotmected to the wire carrying the plumb bob, wiiile the ether pole in
coimectod through a delicate galvanometer to an ijon cylinder sur-
rounding the plumb bob and insertcKl in the water, thus forming a
"stilting box/* When the pliinib bob touches tljc surface of the water,
sufficient current passes to deflect the galvanometer wldch is placed at
•WDe convenient point near the scale board {Eng. Rec^ 1913, p. 192).

The most accurate gage ia, however, the hook gage invented by
Boj'deo about 1840. This takes advantage of the surface tension of
^^f^ water surface, and consists, as the name implies, of a hook attached
^ arod carrj'ing a scale, which may be moved up and down or clamped
*•** A supporting contrivance provided with a slow motion arrangement
^d varoier. The gage is operated by lowering the rod until the point
^0^ thfi hook is below the water surface; the rod ia then raised slowly until
[* protubera&ce on the water surface is noted just over the point o?
tlioolu The point of the hook does not break the surface of the
iiomodiatoly* but carries the surface film up with it and the be-
i^nning ol tliis phenomen can be vejy accurat^^ly noted by watching
rsflccted light upon the surface. In a good light, with suitable
^CfTiiew, dillerenees as small as 0.0002 ft. can be dt^ormined.

A giLgfi of this character, known as the Boyden hook gage, is on the

*Ari[et, Tills gage has a frame of wood 3 ft. long by 4 in. wide, in a

ctangtdfir groove of which is made to slide another piece carrjnng a

let - graduated in feet and hundredths, from 0 to 2 ft* Con-

**©cit : Ik; acale is a bras.s screw passing through a socket fastened

^ uiotber sliding piece, which can be clamped at any point upon the

ime, and the scale with hook moved in either direction by the milled

lut or alow motion screw. The scale is provided with a vernier which

Dtting to be read to thousandths of a foot.

riiait a number of disadvantages, particularly when used in

ion with sewer gagings. The most serious are; 1. The material

htf^y wood, which is objectionable for permanent installations in

^mmp lAsmns, 2, The zero and vernier of the gage are at one end of

lh» iaitrimient, while the slow motion screw is at the other end, thus

^SM^m it v«r>* awkward in operation.

A much more satisfactory type of hook gage is the Emerson gage,
^' ' M Church's ^'Hydraulic Motors." This instrument is accu-

^ and convenient to use, but is heavy, not very portable,

expensive.

308

AMERICAN SEWERAGE PRACTICE

placed on the market the hook gage shown in Fig, 119. Thia la ea(

strutted wholly of non-corroaive metl
is light; strong and haa an adjunUll
hook.

Setting Sewer Gages (Water Level
Recorders) •^Local condiUona will H^
terrnine the locationa of the points %X
which gages should be est:
however, always necessan
for a considerable distance upstream
for a less distance below the gage shm
be in such condition that the quanli
flowing can be computed frora the depl
in the sewen The croed-sectiau aud ali
must bo uniform^ there must be no
and no irtlot^ or obatructioaa to cause
turbance in the flow, and the ctttKJiti(
of the interior should bo known m tluit
coefficient of roughness can be applw
with a good degree of accuracy, M<
over, the velocity of flow in the m
should not be great. In order to
sure of the resulta, it is necessary to \a\
gages at each end of such a stretffa
sower, to determine the HJope of the w^ftt*
surface.

Gaging apparatus sho\ild be installed
a separate chamber or gaging manhola
one side of the sewer, to prot«*ct the
atruraents and make them easily iirc<
ible for obser\'ation or adjustmeiiL Tl
chamber should be connected with
sewer so that water will stand in
chamber at the level of the sewage in
sewer. It is desirable to have a sm»lj
flow of clean water into and tlutiugh
gaging chamber and thcnco to the
in order that the liquid surroundlag
instruments or floats shall be water
not sewage, thius avoiding cloggij
derangement, as well as rendei

chamber a much pleasanter place to enter than it would be i

filled with stagnant sewage.
An excellent example of a apecial gagbg chamber or manbok

i

2
1

U

Fia. 119. — Hook gage sug-
gested by authors (Gurley)*

GAGING STORM-WATER FLOW IN SEWERS

309

rn in Fig. 1 20, an iliustratian of the chamber constructed by the
divbion of the City of Cincinnati. This m arranged for a gage
of the diaphragm type, from which the pressure pipe will be conducted
through a wrought-iron pipe to an iron box mounted at the curb

Cross Section

Fig, 120. — Gaging
t'luiniber> Cincinnati sewer-
age system.

Sectional Plan.

' Ifwortier within a house. If a float gage were to be used, it would
»liBoo»ary to locate the recorder within the chamber or up<*n a post
' ^in » building tiirectly over It. The location within the rhnTuber is

310

AMERICAN SEWERAGE PRACTICE

objectionable, owing to the rapid corrosion of the clockwork and olb«f
partd of tho inatruinent, as well as to the effects of motnture upoo
the paper chart. Where the sewer ia in a street it is usually not pcmhk
to tcK'iite a builrliiig or even an iron post and box directly over the Am;
chainbt^r, unless tho latter is extended so as to lie at least partly uiidiT
the sidewalk. While the design of the gaging chamber is good, Ik
connection between it and the sewer may be criticized, becaujie it is
not normal to the inner surface of the sewer, and therefore the '
in the chamber may sometimes not gtand at the same level ai^ ;
sewer.

ii6a^C^ppv3tryg

Ccfip§rjfrip
Copptr Strip tB

Section of
bagc and

Pipe Cosing.

tocation of Oa^e
on Sewer

FiQ« 12 L — Maximum sewage flow gage (Ciadimati).

¥trh'iQ! Stchm,

Maximum Flow Gages. — In its simplest form» a maxim uiii flt>*j
gage couiiistt? of a strip of wood held securely in a sewer in a vertic»lj
position, and so coati'd that it will show at a glance how much d ti
strip has been submerged at any time since it was put in place

The first maximum gages consisted simply of strips of wood '
unth whitewash, and fastened firmly into the n^ ' f,'^t

make more certain the determinatioti of the point i vij'l

GAOISG STORM-WATER FLOW W SEWERS

311

had riacn, tend was imbedded in the whit^waati, and mucilage wa8 used
to Wp rt'lain the saiul, it being supposcfl that the sand would fall
iWiiy from the portions which had been wet. It has been found, how-
wer, that eometimea the moisture in the atmosphere would cause the
whiu^wash ami sand to disappear from the strip where it had not been
•ubmerged, and sometimes they would continue to adhere in spite of
immftntion.

The illustration, Fig;, 121, sho\in9 a maximum flow gage which has
iiwn deviMed by the sewerage engineers of the City of Cincinnati, H- S.
Momo, Engineer in Cliarge, to overcome these defects. It wU be noticed
lliftt to damp the rod firmly in place it is put inside a 3*in. steel
I«pe m^ir&i in an upright position, with openinj^s near the bottom
to Allow the sewage in the pipe to rise and fall with that in the sewer.
The rod itself is supported by a wood screW held by a ** bayonet joint,**
ft Jot ill the pipe ha\'ing a right-angleil change of diret^fcion. The rod
*Wf carries a series of vials so fastened that their mouths are I in. apart
^'Wtically, It is therefore obvious that the sewage has been at least as
tti(5h hti the highest vial wliich is found filled; and it is only necessary to
invert the roiJ and empty the bottler, and then replace the rod, to have
thn gage ready for another obaer\'ation. Tlu,« gage has proved satisfac
^*0* under ordinary conditions, but the results were not satisfactory
•^ien veiofJties greater than 8 ft. per second were encountered. A
j wmii^ jpi^^ iijig j^p^jj ^jg^ ^^ Pawtucket, R. I.» by George A* Carpenter,
|cily engincLT.

In Bout on, Mass,, maximum sewer gagings are recorded by a circular

: float, with a cHjlral opening through wliich a vertical guide rod runs,

' *»<» fit in a ver>- Uxxse one, but a pair of sheet brtiss springs attached to

^Hr ficiat pre>*8 hghtly on the guide and hold the float at the liigheat eleva-

*«4ri Ui which it is liffcch

ACTUAL MEASUREMENTS OF STORM -WATER FLOW

It must be admittcni t hat the detenniFuttion of the run-ofT factor from

=*'ia! gagiagw is extremely unsutisfuctory. Only a limited number of

-Tiig?* Iwivo beeri made, and e\*en the best of these leave much to

^ulhI^ and the coefficients deduced from them can be considered

^y fiM approximations. NevertJieless, these measurements are of

", not ordy because they furnish the only exfwrimental

*! the run-off factor which are to be had, Ijut because a

["•■Mill utudy of them aids materially in training the judgment and in

•itiviin at A dear and full conception of the problem.

b ihft pfownt state of our knowledge, only sound judgment based
'^f rrf#- ami rh*ar thinking, with a full conception of the various

I'- i irohh'in. vim \u* n^lifHl upon for the selection of fiirtors* to use

312

AMERICAN SEWERAGE PHACTICE

in the design of storm-water conduits, because the existing gs^n^'
are lacking in the deterraination of important elementfl and the chsrac-
temtica of districts are corkstantly changing ^nth the growth of citita,
so that a coeflBcient which might be applicable to-day will be totAily
insufHcient for conditiona likely to exist in the near future.

For an exact analysis of the relation between precipitation &n4
run-off^ it is necessary' to know the true rainfall upon the district drained,
including the distribution of rainfall over the entire area at all Unm
during the storm, and the true storm run-off, including not only Ihir
quantity flowing past the gaging point at all times during an i
mediately before and after the storm, but the amount which coulii
been concentrated at this point if the conditions had been favonibtp.
For instance, if tlio critical precipitation conies at the beginning d %
atomi when the flow in the sewers is small and the velocity of flow
slight, a very considerable portion of the run-off from the surface niU be
required to fill the sewers. In this case the velocity of flow will bo small,
the time of concentratiau will be long, and the actual maximum r&to of
flow in the sewer will be materially less than the real rate of run-off, 11
on the other hand, the critical precipitation occurs after a long |>eriodti^
moderately heavy rain, particularly if accompanied by mcltinii '
when the storage space in the sewers is largely filled and the vlJ h i^
of flow is at a maximum, the quantity actually flowing in the st^irer viill
represent very nearly the true run-off from the storm and t ■
concentration will be a minimum* Whether or not the hi
inlets are adequate to athnit water into the sewer as rapidly as it reaciw
the inlets is also of importance.

Rainfall. — The true rate of precipitation upon the district pjtrf
mui^t be known for each instant during the storm. If the district u*
small one, a single recording rain-gage near the center of the arra my
be sufficient; otherwise several such gages will be required, diBtrilnitM
over the area, since the intensity of rainfall frequently varies widoly
in comparatively short distances. It is extrenicly important that tli^
gage clocks be carefully adjusted to keep correct time, ar
with one another and with the sewer gages, otherwise the
drawn from the records of several gages^ and also those relating lo tiwe
of concentration as shown by a comparison between rain and «wtf
gages, may be material I3MU error.

The matter of travel of the storm is also of importance* 1 *
that if downpour begin? at the most dit^tant point of the dra . ..
and travels toward the outlet, the resulting maximum flow in tb
will have progra^sed some distance before the portions of t*
nearest the outlet begin to contribute water. Thii result i*^
time of concentration for such storms and an increased 1
pared with a storm of uniform intensity over tln^ .-t>i ^r,. < i

GAGING STOBM-WATER FLOW JN SEWERS

313

I which the travel is in the reverse direction would have the opposite

It iit obvious that travel of storms can only be determined by a number
«( pi^ suitably located and with the clocks carefully regulated* So
(ir fis is knowai no records which throw light upon this subject are to
behicL

It is evident that where the rainfall record is that of a single gage,
J pftfticiUarly if at a distance from the sewer district gaged, the inferences

ttiog to time of concentration, area tributary at time of maximum
, and run-off factor, may be considerably in error.
lent of Run -off. — In the great majority of cases the eetima-
tioD of flow has been accomplished by computing the quantity flowing
IB the 8cwer, by Kuttcr^a formula, using an assumed value of the cocffi-
ciwii of roughness^ and assuming the slope of water surface parallel
to the invert of the sower, a record of the depth of flow only being se-
cuml by means of an automatic gage. In many cases the resulting
»tirimtcd run-off may be far from the truth, Horner has found (J(mn
Wat, Soc^ Engs., Sept., 11)13} that:

**Tli«pa are marked differenoes between the grade of the sewer and the
»it^r iiurfaoc grade. For example, in a 9-ft. ^ewer for one rain a depth
otflow at one pioirit of 4 J ft, was observed; 1000 ft* downslream the depth
*Mlf« than 4 ft., though several tributaries entered between, while 500 ft.

'jit IT .:i.^v riNfrnam thv< depth was over 5 ft The sewer is uniform

.:.]., ivH and cKHicIition. The most reasonable explanation of these

'-<'' c I 1 li»it the flow at the upper and lower gages is disturhed, in the case

I' iiii[»* r icagCf by a curve 200 ft. upstream, and of the lower by a 3-ft*

'^il riisdijirging into the main sewer nearly at right angles 100 f I. above

The fact that storage in the sewers may result in a rate of flow much

^ than the rat« of storm-water run-off has already been referred to.

£xt«iit of Drainage Area Tributary .^ — In the case of a downpour of

lew duration than the time of concentration for the entire sewer district

' h the velocities obtaining at the moment of gaging, and in-

i "Ct of the travel of the storm, it is evident that the correspond-

^H rttiwifT represents the discharge from an area less than the entire

i lewiT diirtriet* Where t his condition has be^n taken into consideration,

!*• It hjy* in some of the gagings, it appears that the area lying within the

l^tDiMii^iance from the gaging point corre^sponding to the duration of

J*ttft downpour has been assumed to be tributary. It is not evident

I'^nelber or not this estimate has been l>^ksed upon velocities of flow actu-

l*'y ' ' i it seems more probable that at le^st in some cases

'^'' < have l>een assumed. It is evident, however, that

thtt timo-difitances correctly computed, the maximum run-off

vapour of, say, 8 minutes might come from the portion of the

314

AMERICAN SEWERAGE PRACTICE

area lying between, say, 10 and 18 minutes timenlistance from tlie (
point rather than between 0 and S minutes, particularly if theftrrmcrii
reinforced by the run-off rei^ulting from a following rain at a Icsa^ir [sl
upon the district lying between 0 and 10 minutes tiin<MlisUncc.
detenninations of run-<jff factor based upon less than the t
district above the gaging point are therefore likely to be Ui
error.

Characteristics of Sewer District Gaged.^Finally, be-aring m i
posjiibk' inaceuracioH in the deternii nation of the coefficient of nin-<
it m riecessarv^ to know accurately the eharact«rii5tics of '
in order to form an opinion of the applicability of the
to other districts. These characteristics are of three classes, i^ermancnt,
semi-pennanent, and temporary.

The princi|*al characteristics which may be classed as permanaDii
the size and shape of the district^ the surface slopcjs, and the cl
of the soil. Eveu these are not absolutely permanent, aa they ansi
subject to alteration if extensive grading operations shotdd be umlertakd

Semi-penuanont eharacteristics, those which change but
the extent and kind of the impervious or nearly imper^iut
such ns roofts iind pavements, the extent to which the district is scvd
and the sizes and grades of tiie sewers. The la*^t items are jiarticalit^
important m their relation to velocity of flow and to storage in '
sewers.

Temporary characteristics relate to conditions existing at the time 4
gaging, which may be modified radically within a period of at mowl i
few hours. The most important are those relating to the conditionof t
ground and roofs, whether and to what extent they are wet or dT}\ irt
or covered with snow or ice. Other conditions of minor importance a
temperature, wind, etc.

Inlet Time. — A matter of cooHiderable importanc!e in this oo
and one about which our definite information is very incomplete <
unsatisfactory, is the **mlet time,'* or time required for the Wtt!<*rt
upon the surface to reach the inletn or oatch basins^ It will be i
in the example worked out in the preceding clmpter tliat rarioo* i
times were assumed, depending upon the siae, slope* and other <
teristics of the several areas. In many cases, ' '*t '

araallcr districts, the inlet time may constitute a hn _ <(1

total time of concentration. So important is thw mati**r tiuil
Sewer Department of St. Louis started a special investigation in I
determine tlie time of inlet and the quantity of run-off lor to
drainage districts.

**Two special cases have been taken for the work, one r»^' ' "
prill cipiilly of hunk yiirda nnd alleys in which the slope i« s
uliulc block cloiwtly built and havings ' T"

OAOINO STORM'WATER FLOW IN SEWERS

315

d, and a chamber containing a V-notch weir built under the
str^l belwoen inlet and sewer. Bristol gages are installed to measure head
weirs. All adjacent inlets have been enlarged and arranged aa that
VhU^T can erosa over from one inlet area to another, even in the heaviest
pks; the exact extent and eharacter of the inlet areas have been plotted.
t valutas of the run-off factor from these ainall areas will be of great service
inn ty zing the results from gages in the aewers." — (Horner^ Jour, W, S,
^gcpt, 1913, p, 703.)

Further connmenta on this subject may be found in Chapter VIII» on
ational Methods".

called attention to the defects to which all the recorded
hwat^r gagingH are subject in greater or less degree, it may be well
J reiterate that notwithstanding their imperfections these gagings are
1 af gr4^at importance and should bo studied carefully. It is much to
I (Ic^ircd that the number of gagings should be greatly increased,
licularly for small districts, and that the uncertainties and unsatis-
rtory conditions attending the earlier measurements be eliminated as
I possible. The work now (1914) in progress in several locations,
lly in St. Louis, seems to offer promise of more extended and more
^m iufomiation in the near future. The first step in the acquisition
complete and accurate data must always be the recognition ^
1 avoidance of all possible sources of error and uncertainty,
in part inilarly to be borne in mind that in the determination of the
of! factor it is necessary in most cases to assume the time of con-
ation, and take the rate of precipitation corresponding to the time
nparison w ith the maximum rate of run-ofT. Material errors tn the
Qt may result from erroneous estiiimtion of the time of con-
[i, as is show^n in Table 105 following, in which the results of
ftter gagings at Philadelphia arc given. The coefficients resulting
Di asfluming the time of concentration at 30^ 40, 50 and 60 minutes
! tabulated, and it will be seen that they vary w idely.
The following tables contain the most important dat^ relating to all
fings of storm-water flow in sewers, Tkvhich have come to the attention
f authors. Additional data, apparently of great value, have ai>-
*mi in the 1913 progress report of the Committee on Rainfall and
lltj-aff of I he Society of Municipal Engineers of the City of New
bfk* These gagings are being couthtued^ and no attempt has yet
cti made to interpret the results.

316

AMERICAN SEWERAGE PRACTICE

Tablb 92. — Measurements of Storm- wateb Flow in Sewebs in
Birmingham, England

Meamirementa of D. E. Lloyd-Davies, reported in Proe. I. C. B., vol. elxiv, p. 5. RainfiU
from Edgbarton Observatory in Birmingham — Run-off computed from two automatic lewer
gages for each sewer gaged.

MoseUy Street Sewer. — Area drained 312.5 acres. Population 126 per acre. Am
wholly impervious, 22 per cent, in street pavements, 78 per oent. roofs. Average dope o(
surface 1 in 60. Minimum time of concentration, 18 min.

Date 1004

Max. intensity, of

rainfall during time

of concentration,

in. per hr.

Max. resulting rate

of run-off c.f.8. per

acre

Coefficient - Ratio
of run-off to r&infall

Jan. 10

Jan. 14

Jan. 26

Jan. 27

Jan. 30

Feb. 4

0.330
0.274
0.122
0.210
0.280
0.198
0.297
0.280
0.100
0.132
0.165
0.132
0.297
0.198
0.726
0.866
0.462
0.066
0.326
0.099
0.099
0.139
0.229
0.109
0.264
0.075
0.145
0.065

0.304
0.283
0.101
0.147
0.262
0.246
0.329
0.252
0.088
0.160
0.124
0.139
0.289
0.178
0.795
0.836
0.193
0.043
0.110
0.074
0.065
0.105
0.127
0.065
0.091
0.073
0.110
0.058

0.92
1.03
0.83
0.70
0.94
1.24
1.11
0.90
0.88
1.23
0.75
1.05
0.97
0.90
1.09
0.96
0.42
0.65
0.34
0.75
0.66
0.76
0.55
0.60
0.34
0.97
0.76
0.89

Feb. 8

Feb. 13

Mar. 8

Mar. 29

Apr. 14

Apr. 16.

May 2

May 21

May 27

July 26

Aug. 5

Sept. 3

Sept. 12

Oct. 1

Nov. 7

Nov. 10

Nov. 21

Dec. 4

Dec. 5. . .

Dec. 10

Dec. 12

Dec. 14

GAGING STORM-WATER FLOW IN SEWERS

317

Table 92. — Measurements of Storm-water Flow in Sewers in
BiRMiNQHAM, Enqland (Continued)

CkaHatU Road Sewer. — Area drained 232 acres. ImperviouB area 18 per cent., of which
ptremeots constitute 10 per cent. PopuUtion 17 per acre. Minimum time of concentra-
tion, 12 min.

Date 1904

Max. intensity of

rainfall during time

of concentration,

in. per hr.

Max. resulting rate

of run-off o.f.s. per

acre

Coefficient — Ratio
of run-off to rainfall

Jan. 14. .
Jan. 28. .
Jan. 27. .
Jan. 30. .
Feb. 4...
Feb. 8...
Feb. 13..
Mar. 8. . .
Mar. 29.
Apr. 14. .
%. 16. .
May 2. . .
May 21..
May 27..
July 26. .
%5...
Aug: 17. .
Aug. 22. .
fept. 3. .
Sept. 12.
^ct. 1. . .

0.274

0.122

0.210

0.280

0.198

0.297

0.280

0.100

0.132

0.165

0.183

0.297

0.198

0.68

1.04

0.675

0.338

0.165

0.100

0.420

0.176

0.054
0.025
0.040
0.074
0.039
0.081
0.049
0.029
0.030
0.032
0.040
0.072
0.030
0.181
0.273
0.128
0.051
0.048
0.025
0.098
0.049

0.20
0.20
0.19
0.26
0.20
0.27
0.18
0.29
0.23
0.20
0.22
0.24
0.15
0.27
0.26
0.19
0.15
0.29
0.25
0.23
0.28

BordetUy Street Sewer.
PopuUtion 146 per acre.

Jan. 27
Jan. 30
Feb. 13
Mar. 8

—Area drained
Minimum time

19.32 acres. 100 per cent,
of concentration, 6.5 min.

impervious surface

318

AMERICAN SEWERAGE PRACTICE

Table 93. — Gagings of Storm- water Flow in Sewebs in Cambbiogi,

Mass.

Reported by John R. Froeman, "Report on Charles River Dam/* and intwpntedbf
Samuel A. Greeley in Jour. W. S. E., Sept., 1913.

Tributary area, acres

Percentage roof area

Percentage street *irea

Percentage lawns and gardens

No. of houses

Houses from which roof water runs directly to sewer.

General slope of area

General character of soil

Shepard St. i Shemum 9l

66.5

68

12

10

24

18

64

72

155

292

80

87

0.028

O.Q

8an<iy

Clay

Time of concentration not given; assumed by Greeley as 20 min. in both caaes. Biin
measured by ordinary gage between drainage areas, and by automatic gage about 1 nfli
distant.

Date, 1900

Time after be-
ginning of rain,
Hr. Min.

Av. rate of rain-
fall for 20 min.,
in. per hr.

Max. rate of dis- I p i,
charge in sewer, | ^^
c.f .8. per acre

Gagings during long steady rains

Shepard St. Sewer
Feb. 25

May 3.

Sherman St. Sewer
May 3

2-10
3-55
^30
6-20
5-25
6-25
8-25

5-35
6-55
8-35

0.30

0.34

0.276

0.27

0.43

0.56

0.30

0.43

0.565

0.33

0.07
0.13
0.15
0.16
0.05
0.14
0.095

0.028

0.44

0.33

0.38

0.5S

0.

0.1^

0.22

0.32

0.6S
0.7S

i.a

Gagings of run-off from heavy summer showers

Shepard St.

July 25...

Aug. 10... .

Aug. 27....
Sherman St.

July 25...

Aug. 10....

Aug. 27....

1.00
0.70
1.80

].00
0.70
1.80

0.32
0.35
0.51

0.45
0.20
0.70

0.32
0.5C
0.2S

0.4S
0.2S
0.39

Gagings of run-off from steady heavy rains ^ on ground previously saturakd

Shepard St

Sherman St I

aAOiSa STORM-WATER FLOW /.V SEWEHS

319

I — GAOixas OF Storm- WATEB Flow ik Sewkbs is CAMDRtDcic,
Mass.
%ty Entr. Lewie M^ HiiAtinKs iu Hun-off Cemmillve of Bcuitoti Sue. C E*

iHu 1

Mwm, rulf ti( ruin-

Duruljoij ol thift

M»i. ttue of run-

Cwffi-

ftttK in. per Ur.

mttt

off, c.f.ft. per »rrc

cionl

11^ ^JLyofrf 5Rr«er 5«cw, (See priced

UnK Ubie for do«erii;»(ioii of diMtricv)

Ki2

0 28

1 lir. 10 ni.

0.19

0.68'

^■22

0.35

0-30

0 31

0.86^

^B2$.

0.3<)

0*30

0.07

0.23'

^■25.

0.34

0-30

0.135

0.40

^■25.

0,27

0-35

0.15

0.56

^K25.

0 26

1-00

0.16

0.62

^■^5,

0.20

0-40

0.09

0.45

^■3.

0 5«

1-0

0.13

0,23

^Bg

0.30

0-50

0.10

0.33

^K 17

0,36

3-40

0.17

0 47

^K 18

0^)

0-30

0. 135

0.15

^K IH

OJK)

0-30

0,18

0.30

^K^i

0 62

(K25

0.22

0.35

^■9

0 52

0-20

0 17

0 33

IK 25

0.15

0-30

0 08

0 53

prtmuU fiQt^it: mi *tioir,
k S^t*t .!<*«fr.^Arni ZTS ■kti^, Flow mcABurcd over wplr. No dutii on impcrvtouM
Rminii of \rm ilufitlion thuit 30 mtn. M*i ofnittcd. Sandy eotL FUi ftiupcta.

\. TM, '10

0.20

1-0

0 032

1 0.16

I 4. It

0.52

0-30

0.067

0.15

|£'»

0.23

1-0

0.045

0 2C

Kit.

0 35

1-0

0 05

0,14

i* — McABtraeMeKTs of Storm-watkr Flow in Western OtfTFALL
8ewer, LomaviLLE, Ky,

I i. E- F* ht90d Cht«f Entfr., CommiBaiotiflrB of S^wetikf^, to Rua*off Com-

•H<^ (from lovela). dnvming 2,500 iicrca. Dvpth of flow

, ., - dmiaticv »part; couKitJerfthto diflTprpoc* wa« noted; the

t «, %^ u.o ft nnd ttif di»rhftrge computed by Kuttcr'a formula luinji n

\ Hniii irttie« about lOlK) ft. beyond buumlmry ol dieiirictt and about H4 niiltM

r 1.1 ili«ut«t. A fully drvfiloped pity duitriet, about J46 per c^nt. impervious.

riHf'f *lnrpf< About (HNM Srti I clayey Compuu^d time of flow in iwwpr from

{vfUit — 73 irdnutc'a; tunc of eunn^nUution aatumed aa ftU minuu^A

'10

• 1

Mai> av intt'oaity ol
raiufall for 80 min.,

I in. per Kr,

0 ftp

I

Max. rate of Tun»«ff.
G.f .B. per tkcrv

Coefficient

0 ,12

320

AMERICAN SEWERAGE PRACTICE

Table 96. — Gaqinqs of Storm-water Flow in Sewebs in Cambridqe,

Mass.

Data from City Engr. Lewis M. Hastings to Run-o£F Committee of Boston 8oe. of
Civil Engineers.

Oxford Street Sewer. — Drainage area 400 acres, of which 16 per cent, is made up of pave-
ments and 13 per cent, of roofs — total impervious area 20 per cent. Soil mostly gravdly,
but about 10 per cent, of district is clayey. Slopes generally flat. Rain gage at city hall
about 3/4 mile from gaging station and about 1 mile from center of district. Time ot con-
centration computed as 40 minutes.

Date

n

If

r

Wl

Eemarka

Avs.m, 1909

Apr. 23, 19O0

June 13^14, 1900...,
June l3-i4, 1909....

July 3 ..*...,

Bepl. I

Sept 1 . .

0.13
0.18
0.58
0.31
0.17
0.4S
0.14
0.25
0.08
0.14
Q.15
0.12

0-50

1-0

0-35

0-50

0-35

0^0

UIB

1H3

1-BO
0-40

0.016
0.037
0.08

o.oao

0.024

0,041

0.03

0.(H4

0.015

0.022

0.031

0.033

0.12

0.21
0.14
0.19
0J4
0.09
0.21
O.IS
0.19
0.16
0.21
0.19

Begla^iog of ■torm

2 hr. after beginning of rain

Bt?RioninR of storm

] i hr. after begtaning of TtAn

Ai hr. after beginoing of rain

Bctdnoing of ■tarm

1| hr. after beginning of rmhi

Begin Ding of storm

) hf. nfter bcgipiiiiig of rmin

5 hr. after begiiining ol rain

10 br. afteT bceinnipg of nSn

134 hr. after bc^nnltiK of >^in

Sept. ^7...... .

Sept. 28

Sept. 2S . . . » .

Sept. 28 ....,..,.. .

S*Dt. 28

Flow in Sewers nt

Table 97. — Measurements op Storm-water
Milwaukee, Wis.

Experiments of Logcmann and Nommensen, reported in Eng. Newe, May 30, 1901,
recomputed from published figures which contain error.

Gagings in S-ft. sewer having slope of 0.0025. Rain determined by Weather Bureau
automatic gage and checked by ordinary rain-gage ; these gages 1 to 2 miles distant from sewer
district but records considered applicable to storms reported. Total area of sewer district
1138 acres, of which 18.5 per cent, is occupied by streets. Fair average residential district,
well built up. Several streets have block pavements or macadam, but most of them have
gravel surface. Time of concentration for whole area with maximum velocity in sewer i"
44 minutes; as computed for storms gaged, with velocities actually obtained, time of con-
centration ranged from 67 to 100 minutes. It was assumed that the proportion of the
drainage area contributing to maximum flow was the same as the ratio between duration of
ruin at maximum rate and computed time of concentration under existing conditions.
In only one storm was entire area tributary at time of maximum flow.

r)ftt<«.

1898

July 31
Aug. 2
A UK. G
Aug. 23

Max. av.

rate of

rainfall

observed,

in. per hr.

O.IO
0 2H
0.17
0.72

Time re- ;
quired for
Duration' concentra-
tion with

i of this

I rainfall,

min.

velocity

actually

obtained,

min.

89

75

100

67

Corre-
sponding ;
percentage
of total I
I area con- j
tributingto
max. flow I

33 . 7

100.0

15.0

37 . 0

Precipita-
tion on
tributary

area,

c.f.s.

Max.

rate of

run-off.

as gaged

c.f.s.

Coefficient
» ratio of
run-off to
precipita-
tion

38.3
318.0

29.4
303.0

6.42 I 0.17

65.1 0.20

5.72 I 0.19

117.0 0.38

GAGINQ STORM-WATER FLOW /V SEWERS

321

98* — Measurements of Storm-water i'^ixDW in Sewers in
Chicago, III.

nsi by Sunitjiry Dtstnct ot Chicago, reported by S. A- Greeley in Jour. W, 3, S,,
l^^X'A, Weir mcasurcmcat of dischnrge.

*t*tlt; CKerty SL 5<fu?<T. — 381 Acres, re^idcDtlaL Population per acre — 4,5. Im-
■%ioa« *nia 10 per cent. Distriet Hpproxi mutely reetangular, i X l-O nulo. Hain-gitgo
I. 91. W rnrtier of district, 3500 ft. from gnging point. Time of coucentrAlioti 00 minutes.
I mI area tribiitiiiry iu 20, 30 and 10 minulea, v^ere dKerntine<L

n

Dal*.

m2

i

6

i

Ii"

Bemarka

I -

■s

1

> '3 Q »S

Mil

1 S ;3 I!

« 1 -

III

1

juirao

75

381

Old

52.1

13.5

0.23

Sudden moderate shower

JuirSQ

60

320

o,dO

64.0

15,0

0.23] 12 hr. aft^sr previoun |

fltorm

JalyW

25

100

0.45

73.9

16.5

0.21

Short sharp ahower

Julyja

no

305

0.15

50,2

12.3

0.22

Secood of two showeri

Aig.1

30

105

0.30

76, S

11.7

0,15 Short quick storm

Aiw,0

75

»8l

0.22

82.3

13.0

0.16 & boura after previoun
storm

Stfr 12

20

130

0J)0

no. 8

20,2

0. 17' Sharp short shower

Bmmsttmi Diiti^4 Sf. Sewfr. — ^WeU built-up arcft of 420 aeil», 20 per cent, imporvioui.
Tti&t ul eonconlralioni 40 ml nu left.

I

HI'

XUySK

45

420

0 32

131 0

30 0 0.22

iwomi

15

141

0.00

HI fl

11.8 0.14

Joty 13

to

100

2.10

210,0

27.0 |0.13

Idy 11

45

420

0.16

53 0

10.0 |0 in

Aug 20

iO

100

n 78

78 0

5 0 0.07

Di»rr-»ry Banlmtrd ^r'uivr. — .\rca 725 acres, 22 per cent, impervious. Population d2JS
pn »rr^. l>|«trint 2-4 X 0,5 Wiilo*. Very flat; many of t*>U are lower than etrnela. Time
<i po«e«ttLratiun for whole area 75 minutes: 580 acres tributary in 00 minutits. Near*?st rain-
CH* b at PoMi ofBrift, l,h mibd south: next at Evanston, 8.25 miles north. Intensitiea
Wmd haw b«4in ohtalniKJ by pritpurtinniu^ bctwec^n these two g&ges.

JOitii

0,32

, , . 1 . . 0. 23i Short storm, no previouil

1 rain.

lOclll

725

0,05

.,,..... 0.07, Long st'irm, ground

I

1

1 aonko<).

>trr, — Area 2513 iK^rcn; h.t\ milns long by 0.8 to t-0 mile wide; 7,6 per

Population 15.5 pi-r acre. PrneticuUy Hal; moat lots are below street

iilratiuu for who1« ureji 7 hours. Ari-*a tributary in storms of 2 to 4

th*» tnipfrrvtous surfaec, atiiountitig to about 15 per cent, of that

.'vaL 1 mile ritsUiit.

Jl»|ii 21

120

ftHtJ

0.13

75 4

ft 0

0.07| First part of «torm

im^

120

580

0 W

40 0

0 0

0.18 Lfttt<«r part of storm

m^

180

WK)

0 033

20.7

5.0

0. 17 Last part of long st^rm

Ki

130

580

0.00

34.8

3.5

0. 10 First part ol Ught rain

Ori 13

105

im

0 11

110.0

l^i.O

0. lit LjMt shower in (V-hour
storm

»»rt»>

210

1080

0 o:h

30.7

4.7

0. 13| Long, light rain

»»n- ji

!S40

1200

0 052

fl7 0

18 0

0 27 Last shower of a Itv
1 Itoup ftorm

2]

lAlH^riS&ilfariM

322

AMERICAN SEWERAGE PRACTICE

Table 99.— Measubemknts or Storm-water Flow in FaAHl
Sewer, Hartford, Conn.

RcwuttA of compuiutioiiH by Met<?«lf and Eddy from dut* fn nmner liw r L ^
rra«t. i\mn, Soc. C. E,. imXMrt. p 133: rain r^^^ord « that of city Lll a^Z i - j
^^nter t>( st'wer diatnut. (CompututJoas for atorase in Mw«r apply only to ti
^^dlowancc for ntorage in branch Bowera.)

Qjiced at South St, by recording float guge. Sewer 0 ft. diam dope 0 002
^,T^'""'' to invert. Ar.^ dramed 477 «.re«, re^iden'tUU about on^i^^JT^
thicllly btiilt up* rtmomder .omewhat «pan«. Dennity of populatioa 12 pe? •crt. Ha
conoentrfltion cjitimated to exceed 25 minutca.

Date

lUOO

Condi tion
of sroufid

July 25 ! Dry

July 25 i W«t by pre-

vioufl rain
Oct. g Ditto

11

0.75
l.OO

0.50

o

5

*E

1 1

o «

^ 2
11

U

40
00

85

360
477

23S

il

e >!

3 3

1^

s
1

40
00

65

40

78

22

24

10

04

iOll*
jO.ll

sm uu

GnKod lit Bond St„ by recording float gage, S«wor 4 ft, dlum , fllop« 0.003. Ilfirrt
grtide aaeunietl parftUel to inv<?rt. Area draintNl 263,5 u.crvs, r«siil«ntiiil. dvjimtly biut*
eicopt for iaBiitution uocupyiiig about 50 acrr«, Deoaity of populaaon IJi 3 p«f
Time of conei?ntratir»n estimated to pjireed 22 minutei.

ItKJl

\ 1

Mar a

Covered
with ie«

0.3«

120

167

T

105

23

21S !*►;!

July n

Dry

3.75

20

890

20

75

58

laa 0.1*

W12

Feb. 28

Wet by pre-
viou« rain

i.mi

20

263

?

60

12+

Table 100.— Measurements op Storm-water Flow m Srin;w

Newton, Mass.

Data from Edwin H. Rogers, City Eagiuoert to Eua-off CotutnittM of Eosujir.
Civil Eugineen.

Hyde Brook drainage area* 350 acres, of which about 28 por rant. U ImpervimUk
urhau roaidenco district well dovclop«d. Small hroi>k enclosed in €ovcre>d m*9oarr9l
Kaio-gage within diatriet, about halfway between center and gaging point. Coi
by Kutt«r'a fnrniula using a •• 0.0 13> Gaging point not very aatisfaetory, naat
changed 100 ft. above and 13B ft. below gaging point. Section of channel c*]
above and 21)2 ft below gaging station; at this latt«r point the water fell ovef
fltepi with a vertical fall of about 9 ft. Time of concentration^ 20 minutes

Date

Mai. (IV. rate
of rainfall
for 20 min.,
in. per hr.

Max. rnto of|

run-qff

o.f.«. per

aere

Coeffieieni

HepL 4. 1007.
Aug. 7, 11)08

1.40

2.5.5

0,61
0.71

0 43

0 28

n.,

GAGING STORM'WATEH FLOW IN SEWERS

lOL — MEASfTREMENTS OF StORM-WATEB FlOW IK SiXTH AvB,

Skwer^ Manhattan, New York

' "^^ : !a!ph Hcriiis in 1887-^8 by record! dk float gugc. (Data quoted from C. E.
Grr, Am. Soe. C E.» voL Iviii, 1007, p. 4M).

A - . i^! and pfivcd sectioQ in the lower part of the city, area 221 aerea. regular

iBTluv ilu(>r uf about 0.007* Aboitt W per ecjnt. of an?a imporriou^, roinaindcr grnw.
^(^ukiinD 170 per acre. Time of concc^&tratittD 15 ttiiuuteti not including time required for
»«iArr to rMcb itilctA, nean^at recording rain-eaKO 2 mil** distant.

Date

'Miw. ftv« rate of

rainfall for

p«riod - time of

of ooocenimtion,

in. per hour.

Correflpondiog

max. rate of

mn-oflF ob-

Berved, c.f.a.

pttraera

Coefficteot -

ratio of run-off

to prodpita-

Uon

R«marka

&Q. '28, 1887

0.730

0.290

0.39

■^ 28, 1887

0.25

0.18

0.72

rVb. 25, 18S8

0.49

0.28

0.67

^>b. 25. 1888

0.36

0.27

0.75

'unc 26, 1888

2,367

1.022

0.43

^uJy 19, 1888

1.850

1 0,666

0.36

%U|5. 4. 1888 '

2.910

1.162

0.40

Nearendof atomi

)mm. 21, 1888

2 ^80

0.880

0,40

At beginning of
storm

Rg.21. 1888

1.347

0.470

0.34

Near end of storm

%i»fr 21. 1888

1 20

0.65

0.54

Kn^, 21. 1888

1 07

0.90

0,84

^^m 102. — Mjcasuhjsment or Storm- watkr Fi^w in New York Ave.

Sewer in Washington, D. C.
1Up«rt«d by Capt. 11, L. Horic in Tran* A m. Soc. C. E., vol. i¥v, pp. 81-82.
kntk (UainrxJi 130 nt-'roflt, of which 2fX\ acres are cloflely built, and fftrect« paved with
At; 15t1e ncr*^ npnraely huilt, but «rith iitre«U mostly paved with aaphalt; 80 a«rt*« open
i (ProbftMy 5/i to *Vl> prr w?al, imperviousj. Time of conoentration about 25 minut**B.

Max. ratt* of '
precipitation^
in. per hr. i

Duration,
mia.

Max. rate of

runHjfT, e.f.B.

p«r acre

CofsffieicDt

^uftr26,'$I 4.23 | 25 | 2,00+ | 0,48 +

Arm Abo\*e gaging point 200 acres, nearly 100 per eent, inifjervious.

1884
28, *85.

2-00
0.90

15
37

1,50 ±
0.9CJ

0.75±
I 00

■^muj 103.

MCASFUBMKNT OF StORM-WATER FlOW FROM ShiPLEY RtTN

DKAtNAGS Area, Wilmington, Del.
tkta (mm A J. Taylor, Eiiitin<!«r of Sewers, to Runoff Comiiiltteo of Bostoo Soeiety of
W i:ii(li»Mifa

'^1 acm«. with 31 per oeot, p&vrd surfaces aod 34 pnr cent roofs. Total impervious

[rfv eMiii, Soil rtayey, «enerat surface slope about 4 per cent. Flow cufii{fUl4*d

f turmtila usring « •• 0.015, Oaitiitic iwint not v<^ry satiafactory, as grade and

iKTtii rh*nfred 1 40 ft. abovv and 15 ft. below point where depth was gaifed. Timfl of

'*■"■ titration not kjv<»ti: aaaumfd not to eiooed 20 miDuUifi.

Max raitifall ratt* for
2t) mtn,, in pr*r hr.

Ma*, rate of run-ofl^
e.f s. per acre

Coefllctetit

3,90

3 t

0.79

had bf«en falling heavily, but at a somewhat leaser rale» for 36 minutes before
of the downpour, «hieh eaoaed the maximum nio-K^IV.

324

AMERICAN SEWERAGE PRACTICE

Table 104. — Measurements of Storm- water in Flow in Newell
Ave. Sewer District, Pawtuckbt, R. I.

From figures reported by Qeorge A. Carpenter, City Engineer, to Run-off Committee d
Boston Society of Civil Engineers.

Drainage area 146 acres, of which 25 per cent, consists of pavements and 9 per oeni of
roofs — total impervious area 34 per cent. Soil, sand and gravel covered with 2 ft. of loam.
Average surface slope less than 2 per cent. Rain-gage about 1 mile distant. Slope of wtnt
changes at gaging point; no change in section for 2250 ft. above gage; outlet is 545 ft. below.
Flow computed by Hasen- Williams formula with e ■• 150, using slope of sewer down<«treaa
from gage. Time of flow in sewer from most distant point computed as 23 94 minvta.
Concrete sewer with very smooth interior; c ■• 150 justified by careful chad
measurements.

Max. rate of

Duration of

Max. rate of

Time after

Date

rainfall.

this rate.

run-off, c.f .8.

Coefficient

beginniof

in. per hr.

hr. min.

per acre

of storm

Spring months

Mar. 25, '09

0.26

0-48

0.092

0.35

Summer months

Aug. 26, '08

0.50

0-30

0.16

0.32

June 17, '10

0.22

0-50

0.071

0.33

Aug. 15, '10

0.20

0-45

0.058

0.31

Aug. 28, '10

0.24

0-35

0.064

0.27

Fall months

■

Oct. 20, '06

1.02

0-35

0.302

0.30

Sept. 4-5, '07

0.69

0-25

0.299

0.43

Sept.28-29,'07

0.29

0-50

0.128

0.44

Oct. 8, '07

0.46

0-50

0.189

0.43

2hr.-40m,

Nov. 4, '10

0.23

1-07

0.112

0.49

Nov. 29, '10

0.17

1-40

0.044

0.26

4 hr.-20m,

Winter months

Dec. 23, '07

0.51

0-37

0.295

0.58

Feb. 19, '08

0.70

0-54

0.462

0.66

3 hr.-15mL

Feb. 26, '08

0.15

1-28

0.075

0.50

\

Feb. 26, '08

0.22

1-0

0.192

0.87

V

Dec. 7, '08

0.30

2-10

0.148

0.49

6hr.

Feb. 10, '09

0.30

0-30

0.148

0.49

Table 105. — Measurements of Storm-water
Philadelphia, Pa.

Flow in Sbwebs

Gaging point in 13-ft. sewer at Twelfth and Diamond Sts. Data published in asB^
reports of Bureau of Surveys supplemented by information submitted to Run-off Cominitr 4
of Boston Society of Civil Ensincers by George 3. Webster, Chief Engineer, Bureau of F
veys. Intenflity of rainfall for periods from 10 to 60 minutes duration are gfreik ia tMi
original reporui and tlie ratio between run-off and the 30-, 50- and 60-mintito
tion rates ha» been computed from them.

Area drained 1360 acres, two-thirds of which is improred property. TIbm i
sewer at maximum velocity about 33 minutes. Time of
minutes.

TlMolflovA J

GAOING STOBM-WATER FLOW IN SEWERS

325

Intensity of

rainfall
for 40 min.
in. per hr.

64»
45

1.39
1.71
1.23
1.32
0.77
1.94

0.89
1.65
1.25

0.77

1.42
0.62
1.42

1.00
0.83

0.69

0.80
1.30
0.87
1.45
0.85

1.35
0.75
0.92
0.59
0.60

1.24
1.00
1.24
0.45

Max. rate of
c.f .0. per acre

Coefficient

Ratio betwect

rate of flow an

fall rate fo

30 min. 50 min.

1 max.
d rain-

r

60 min.

0.49

0.30

!

1.33
1.02

0.92
0.73

0.62 0.90 1.04

1.05

0.61

0.47 JO.70 '0.83

0.88

0.72

0.58 0.77 0.92

0.94

0.71

0.60 0.86 1.03

0.71

0.92

0.76

1.04 1.17

1.02

0.53

0.45

0.63 |0.70

0.87

0.98

0.79

1.02 ; 1.10

0.94

0.57

0.46

0.71 ;0.85

0.89
0.55
0.53

0.71

0.56
0.59
0.54

1

1

0.69

0.83

0.93

0.84

0.59

0.45

0.71

0.85

0.90

1.45

1 08 i 1.73

1.92

0.96

0.68

0.63

0.83 0.98

0.70
0.72

0 64

0.72

0.65

0.85 1.02

0.70

0.84

0.80

1.06

1.17

0.56

0.82

0.72

0.94

1.02

0.61

0.76

0.58 0.88 ' 1.03

0.94

0.72

0.60 0.80! 0.90

0.41

0.47

0.40 0.58 0.65

1.06

0.73

0.56 0.91 1.10

0.59

0.70

0.68

0.71

0.75

1.03

0.67

1.09

0.81

0.64

0.96 1.16

0.88

1.18

0.88 1.47 1 1.60

0.88

0.95

0.77 1.09 1.20

0.46

0.78

0.69 0.98 0.98

0.51

0.85

0.81 |0.89 0.92

1.01

0.82

0.62 1.01 1.19

0.81

0.81

0.74 0.90 1.00

0.98

0.79

0.78 0.92 1.03

0.59

1.31

0.95 1.79 1.79

1.06

0.77

>45 Bifiaies.

^^^H Table 106.— MEAstTEEMEXTs or

Storm-water Flow ik SiswBi^n^H

lioCHCt^TEft, N. Y. ^H

^^^H Gasiavi of EmQ KuichUBg. data from Tran: Am, Sac, C, S., vol. zz, 18S9, p. 1. Ga^H

^^^^H inga mftde by tmvx. flow

F^KiM, dBt«rminin« slope from raoorda of pain of gages. Bai^^^

^^^^^H carefully meaBurcKi but not by automatic fcageA,

^^^H District J,— Arva 350.9 acres, r^aideotial; about half fata« population of 36 per acr*; vm^

^^^^H m&iticter ipar»«ly settled, a^icuIttirsiL

Soil moatly clayey loam. Earth roaila. Maj^^H

^^^^H time of Bow in sewem

estiniatod at 34

minutes. Time of concentration 44 minut«^^|

^^^^^H Iinpervioiut area 15 per cent.

1

i

Corre-

Coeffi-

y

Max.in-

flponding

Max.

cient -
ratio of

1

I

fcetwity

precipi-

!HJwer

dia-
charge

Date

of rain-

tation

dia-

lUmarka

fall, in.

nn drain-

charge.

p«?r br.

age orca.
c,f,a.

Cf.i,

to pre-
capita-

tion

1

Dee. 10. '87.

0,31

no. 6

15.3

0.14

Preeeded and followed by Ugliter rainj

Apr. 5, "88..

0.24

86.7

8.94

0.10

Preceded and followed by liizhtc'r raina

n

May 4

0.30

107.1

7,32

0,07

Preceded and followed by Ught4>r niina

1 1

MayO,....

1.33

460.5

77.0

0.16

Sudden shower, followed by light rain

M

May 12....

0.30

107,1

11.8

0,11

Preceded and ftjllowed by lightrr ratJ^

■

May 26. . _

1.00

356.0

30.8

0.09

Preoe<led and followed by Ughtisr rmill ,

■

JiiiieS

0.40

142.8

7.81

0.06

Sudden shower

■

Iuae34,...

1.65

553,2

40.7

0.O7

Sudden ahuwer '* *

■

June 24....

2.62

935,1

58.S

0.06

Sudden ahower *' " "

■

Jun<j28....

0.80

285.5

40.7

0-14

Pnwedod and followed by ligkier ra]

■

July IL.,..

0.76

271,2

l&.»

0.07

Heavy «hcwer precwled by lighter raj

■

July 18

0.75

267,7

20.5

0.08

Preceded and follawed by liirht-r rati

■

AiiB.4

1.00

356.9

16.5

0.05

Sudden shower '*

^

Aug. 16.,,.

1.63

576.6

27.3

O.OS

Sudden showrr

Au«. 17... J

1-33

475.0

25.8

0.06 8udd«n »howttr

^^^H

2.50

892.4

35.3

0,04 Intenaity estimated roughly

Stipt. 1«,.*.

0.47

167.7

33.3

0 . 20 Sudden ahower followed by light4^r ralu

DiMtrvei /r— WeU*de

vr^loped area of 1

23.7 acre«i about 4800 ft. long and 12(10 ft. wndm

•

^^^^H Av. d«iudty of populati

on 32 per oere.

Many butineas blocks in oae portion, r^tuaifider j

^^^H reside ntiaL Soil mosth

' clayey loam, i

ibout H of atreela paved, moatly with macadamu J

^^^^^1 but flomfl flioae blook am

1 asphalt. Time of

00 w in eewer. 18 minutaa. Time of eoncentratiqflH

^^^^^^^H

20 minutea. Impcrvlou

m area about 30 j

>«r oenU 1

^

Dec. 10. "87. 0,:tl

3V»,9

9.27

0,24

Preceded and followed by lijcht4.*r rain

]

Apr-5, *88.,

0,24

30.9

4.80

0 16

Pree<?d«d and fitllowed by litthtrr raiu

^

May 4

0.30

38.6

5.56

0.14

Preeoddd and followed by Ughl^sr raii^^|

MayO.....

1.00

128.7

33.7

0.26

Intetutity eatinvntod

^H

May 12 ..

0.30

38.6

6.00

0.16

Preee«ied and foHow».»d by linht^r rail

^1

May 26

1.00

128.7

33.3

0.26

Preceded and follovuvl by lig^ll^*r fiiil

^1

Juno 2

0.40

51.5

4.67

0.00

Suddon »hower

^1

June 24....

2.62

337.2

71.3

0,21

Sudden »how» r

^1

Jun<* 28 ...

0,80

103.0

30.5

0.2d

Prvceded and ^<^l^^^^*-l Uy htthyitmm

^1

July 11

0,76

07.8

IS.i

0.16

Heavy ahowvr prrcedi'd by ligb|(^^|

^1

July 18

0 75

f»6.5

11.8

0 12

Prrr « - MollQwed by Ugh«i™

^1

Aug 4

1.00

128.7

12.8

0.10

Su i ** ** ** •

^1

Au«. 16....

1,62

sim.o

25, Q

0.13

Sud ^ r " " '*

^1

Auft. 17..-.

1.33

171.6

14-»

0 00

Huddoii nhowi '

^1

Auif. 36....

2-50

321-8

39.3

0.12

Sudden show* r

^1

Sept- Ifl ...

0-47

mji

23.1

0 38

Suddim nhfTwtrr

1

GAGING STORM-WATER FLOW IN SEWERS

327

XMHd tX. — Well-developod mftideotlAl diitrict of 133 heteai poptilatico 36 p«r acre.
^DmdUfitfi mmUly largo and mther oiom toigcther. Streets mcNitly mmcttclAm or gravel.
loamy. Time of flow id »^wvt^ 15 minutes. Time of ooDctentratian, 23
Impcrvioui area about 38 per cent*

IW, i<1. -87

0 31

41.2

17.1

0.42

Prt-eeded and followed by lighter ram

Apr, 5. '88.,

0.24

31.0

13.3

0.38

Preceded and foUowcd by lighter rain

Uir«

0.30

30.0

14.4

0.30

Preeeded and followed by lighter raiu

M*yd

0 na)

90.8

29.0

0,29

Intensity catlmatod

iUyia...,

0,30

30.0

U.8

CIO

Preceded and followed by lighter rain

iUyn..,.

1,00

133 JJ

21.9

0.10

Preceded and foHowed by lighter rain

'Ulfl,,,..

0.40

53.2

20 0

0.38

Buddon shower

i««.«....

s.oa

348,5

46.0

0.13

Sewer surcharged

luatas....

0.80

106.4

37.5

0.35

Preeeded and followed by lighter rain

%lt....

0.7«

lOM

22.1

0.22

Heavy shower preceded by tighter raio

J%l*.....

0.7S

00.8

14.8

0,15

Preeeded and followed by tighter rain

AnH-,.,.

1.00

133.0

19,0

0.16

Sudden shower '* " '* **

^16....

1.63

215.0

38.2

0.18

SuddcQ shower

Kit..,.

1 33

177.3

21 1

0.12

Sudden shower "

Kss...

a SO

333,6

4«,0

0,14

Sewer surcharged

^^^«(n4 A', — W«*lI-dcvQlof»6d area of 85.1 ttores. with poptilatioa of 40 p'^r aero, long
^*nrm itrip eDoiaiaing many buaineai btoeks and apartment bouaes, as well na single reai-
^9ma, flireeta mostly macadamised. Soil clayey loam. Time of flow in Mwen,

lOmiotttM. Time of conopntration. 1ft minutea.

Impervioua area about 50 per cent.

IW TO, '87.

0,31

7,80

4-54

0,58

Preced**d and followi>d by lighter rain

M»yi.'fi8,.

0,30

7.54

4.89

0,65

Pri*ceded and followed by lighter rain

Mi,»,..,.

0 75T

18.a

0.81

0.62

Intensity eatimatiKl

Mv 13. . , .

0.30

7.54

2.66

0.36

Preceded and followed by lighter rain

JUyJfl....

1.00

25,1

7.94

0.32

Preceded and followed by lighter rain

iUM34...,

3.02

«S.8

21.0

0.32

Sewer sureharged. Flow estimated
at malt, capacity before surcharging

^«s3«l....

0,80

ao.i

7.09

0.35

Preceded and folfowf^d by lighti*r rain

i^ll

0,75

10. 1

8,01

0.41

Heavy shower preeeded by lighter rain

hhVL..,,

0.75

18.8

4.70

0.25

Preceded and followed by lighter r:un

A«H«....

I.flS

40. ft

10.0

0.25

Sudden shower. *

AtlH7 ...

1,33

33,6

6.17

0,18

Sudden shower

i«*»i.,,.

2 50

02,8

21.0

0.34

Sewer surcharged

JkMleid jrVfJ-^^Wittt-d^veloped area of 02.3 acre*. Popuhiiion 35 per acre, Omvflfth

11 halt, one-fourth with stone block* remainder macadam and gravel.

residenceji; sornu business blocks and apartments. Soil clayey

Lur ,M, .» is ni'arty level. Max. time of flow In aewers, 16 mlnuiea; time of

P***^«tration, 24 mu*\iij^9. Iniprrviottt area about 30 per cent.

Utt. 10. *87-

0.31

28.6

7,43

0,26

Preeeded and followed by lighter rain

Apr.5.'H«..

0.S4

22 3

4,61

0.21

Preceded and followed by Jightrr rain

||tv....

11.30

27.7

7,82

0,28

Preceded and followed by lighter rain

K»....

0.75 ?

60,2

18,0

0,215

Intensity estimated

Via....

0,30

27.7

4.70

0.17

Preceded and followed by lighter rain

«*»«....

1 IXJ

09.3

10.8

0.12

Preceded and followed by lighter ruin

J«w«

0,40

36.9

3,23

0,09

Budden shower

i^U,,.,

2,62

241.8

28,5

0.13

Sewer surcharged

W».,.,

O.W

73.8

27,7

0.37

Preceded and followed by lighter raiiil

'«lfU..,..

076

70.1

13, «

0,10

Hea^T shower preceded by lighter rain

^iifw.....

0.75

60.2

7,U

O.IO

Preceded and followed by Ughtt^r ruir*

A'**

IJW

02,3

12 7

0.14

Budden shower ** **

AflUft....

1.62

H9.2

28,5

0.10

8ewer surcharged

Aai7...,

1.33

123.1

10 9

0.09

Sudden shower "

Km....

2.50

230.8

28.5

0,12

dewcr surcharged

mu

0 47

43.4

10,1

0.37

Sudden shower

CHAPTER X
SEWER PIPE

Until recently, sewer pipe was given thicknesses which were the net
result of the experience of makers and users, theory having little part
in settling such dimensions. Recently, however, the great increase
in the use of vitrified clay and cement pipe for sewers and drains,
and the steady complaint of breakage with both classes, have led to both
theoretical and experimental researches into the subject. It is naturally
divided into two parts, the pressures which sewer pipe must resist and
the stresses which are produced in the shell of a pipe.

INTERNAL PRESSURE UPON PIPE

The stress due to the internal pressure upon pipe is indicated by the
formula

« = —»/ = — > in which
( s

8 = tension in pounds per square inch upon the pipe,

p = pounds pressure per square inch of water in the pipe,

r = radius of the pipe in inches,

t » thickness of the pipe in inches.

In general it may be said that the working stress should not exceed
from one-fourth to one-fifth of the ultimate strength of the material,
if reasonably ductile as steel. In such brittle material as cast iron
a much larger factor of safety than four or five is used, as appears in
the following paragraph.

PRESSURE IN TRENCHES

One of the earliest attempts to ascertain the pressures produced in
a trench by backfilling, was made by August Friihling in "Die Ent-
wasserung der Stadte," one of the volumes of Franzius and Sonne's
" Handbuch der Ingenieur-Wissenschaften." He assumed that the ver-
tical pressure due to backfilling, increased at a diminishing rate as the
depth increased, until at a depth of 5 m. no further increase occurred.
Further, he assumed that the total pressure at any depth varied accord-
ing to a parabolic law. From these assumptions he deduced the following
formula:

328

SEWER PIPE

329

_ffhc!rc P ifl ilie pressure per square meter of horizontal surface, w ib

^he weight of a cubic meter of the backfill and .4 is the depth below

iJijrh there is no increase in P, If ilua expression is transformed to

Flfiglidh nieasuro8 and m ia taken at 100 lb« per cubic foot, the formula

I p = procure in pounds per square foot at a depth of t ft.

Barbour £jq>eriment8. — The I'Tiihling formula has been rarely if ever

vmA in the United States^ where until 1910-11 cxfK?riments by F. A.

Barbour {Jour, Amm^ Eng, Soc^ Det\, 1897) were the basis of most

diacynsions of the subject. His tests were made by placing a modified

' ' iM* ratn in the bottom of a 13-ft, trench and supporting a plat-

ihe plunger. ISheeting was placed across the trench at each

end of ihe platform, so as to confine the backtill placed on the latter.

Thus flpries of experiments wa^s not utilized in developing a formula,

but the results were expreivsed in a number of curves* These give

nncsHurefi than the Friihling formula at depths le^ than about

I'l greater pressures below 15 ft.

Bazen's Analysis. — Baaing hm calculations upon Prof, Talbot's work

on the iitnmgth of tliin rings under external pressure, Allen Hazen

ffuggn*t>f^4i trntatively (Jour. N, E, W. W. Assoc., May, 1911), two for-

muiaa for determining how thick a pipe must be to carry the stressea

due to Uic Imckfilling as computed by Talbot's formula, and at the same

Uroe to carry a given internal pressure with 50 per cent, increase for

wmliir nun. An abstract of his statement follows:

Ll*l ti « diameter in inches,
** thick QOfis in inches^

« depth of biickfill al>ove top of pipe in feet
» |i«n«issible stress in povmtis per square inch in cast-iron pipe, whioh

1 now take as 4400 lb. fcir an ultimate tensile strength of 22,000

lb., with a factor of safety of 5«
= wdidit of fill over 1 lin. in. of pipe at the rate of 115 lb. pet cubic

fi>ot, the outside dtatiieter of pipe being taken as 5 per oent.

grralcr than ti.

W - Fd

1.05xnJ5
144

OSiPd

n'i*king moment normally present from backfill^ atrc^inling to
iTsliHit «* t/lti Wf), D being the average diameter of the shell,
•rhich lit about 1.02M,

M »

l.025c/(0.84F<i) = O.OSSSFd*

330 AMERICAN SEWERAGE PRACTICE

Resulting maximum circumferential stress in metal in pounds per square
inch, obtained by applying the usual formula,

M = g «6/*, b in this case being 1.

6M 0.323Fd«
** = IT = — li

The stress available for resisting the water pressure is 4400 minus this
amount. Of this, one-third is allowed for water ram and two-thirds for
static pressure.

The stress allowable for resisting the static pressure is thus

2/ Fd}\

«, = 3 (4400 - 0.322-^j

H » head in feet that can be carried by a given stress;

« = 7 lb. pressure per square inch

" 2^X2:31*''^

i/= .(4.62J);

and for 82 as reached above,

H = 3.08^^(4400 - 0.322^^*) = 13,500 j - O.mFj

If we had taken the weight of the earth backfill as 116 lb. per cubic foot,
the 0.99 would have been unity, and we may make it unity for the purpose
of simplifying the formula. We shall then have

H = 13,500J - Fj

Our specifications allow a variation in the thickness of casting of 0.10
in. for large pipe. To insure that the stress shall not exceed the calculated
amount at any point, if we could be sure that the specifications were literaUy
complied with, it would only be necessary to add 0.10 in. to the computed
thickness. This rule might be adopted for country work and where an
occasional break in the pipe would not be of the greatest importance. For
city work, or where a break might do great damage, it would seem better to
add 0.25 in. to the computed thickness, this being the allowance made in
the Brackett formula in all cases for this purpose.

Solving the last equation for /, and making this addition, we have

For country work:

< = 0.10 + 27^^(^ + V^54;000FT^^)

For city work :

t = 0.25 -f- 27 000^^ "^ \/54;000F+//«)

This formula is not suggested as in any way final, but only for the purpose
of discussion, and with the idea that it may possibly have in it some elements
of a more rational calculation than are contained in the old formulas.

SEWER FIFE

331

I formulas certainly lead to conservative results, as contiiderahly
ttcr weight pipe than that indicated by them as necessary has been
luUy used in different places. Thus Leonard Metcalf reported
during the diBCUSsion cases in which he had successfully ui*ed 20- and 24-
ff the New England Water Works Association Cla**^s A stand-
ir pths of 18 ft. more or less, though under but slight internal
fture.
lowm Investigattons by Marstoa.— The results of an elaborate in-
fc^tigation of the subject, Iji^sting several years, w^ere made public in
tin 31 of the Engineering Experiment Station of the Iowa State
of Agriculture. This was written by Prof. Anson Marston,
dirertor of the station, and A* C- Anderson, and contains the first
welt-developed comprehensive theory of the subject which waa also
dieekfx) by numerous experiments.

ThiGBC authors use in their anal>^ica! treatment of pressures in trenches
pmcikmlly the same method that was developed by Janssen for the
pvemiras in grain bins {Ketchura's "Retaining Walls, Bins and Grain
Elevalots^'). This gives for the weight on the pipe W = CwlP, in
wllJ€h W 18 the total weight per unit length of pipe, C k a coefficient in
allowance is made for the ratio of the width and depth of the
I and for the coefficient of friction of the backfill against the si<les
the trench; w is the weight of a unit volume of the backfill, and B is
I of the trench a little below the top of the pipe. The values of
Bn in Table 107.
Th(© approximate averages of a large number of measurements of
fcita and friclional properties of different classes of backfilling are
I to Tabic 10S» Within the range of ordinarj^ ditch-fiUing matcriala,
I a large difference in the values of the friction coefficients to make
difference in the weight carried by the pipe. Marston and
point out that the real difficulty in selecting the proper
frcMQ the table lies in deciding upon safe and reasonable allow-
for the probable saturation of the materials under actual ditch
~i!ODditiiiita«

The a|>pnmmate majdmum loads on pipes in trenches of different
lllis and depths are given in Table 109. The investigations of
P|aifid Asdeiaon have convinced them that a 12-in. pipe will have
> load aa an 18-in. pipe, if each is placed hi the bottom
iff a 24*^. trencli, other things being similar* When a wide trcnrh
i^ nef^aeary for construction reasons, they beUeve that, in firm soil, the
liMic) can W greatly diminislied by stopping the wide trench a few* inches
abcrre tho top of the pi|>e and then excavating the narrowest trench in
trhidi H la praeiioiiUe to lay the pipe, making special enlargementji for
if Q(ie<9Quu-y.
^cporimentB to Us*t the accuracy of the theory upon which this

332

AMERICAN SEWERAGE PRACTICE

and their other tables were based were made by weighing the load c>n
difTeretit lengths of pipes hang at different depths in trenches, from *
system of levers ultimately ending on the platform of scales. Particular
care was taken to avoid all test conditions likely to cause uncertainty
regarding the accuracy of the results, and where doubt arose the test3
were repeated, with or without modification^ until uncertainty -WB^
eliminated.

In commenting on Table 109, Marston and Anderson point out that
the side pressure of the filling materials against the sides of the trenc-"^H
develops a frictional resistance which helps to carry part of the wei^Hl.
This frictional resistance relieves part of the vertical pr^sure near t-He
sides of the trench, so tbit at the level of the top of the pipe the vertii^J*!
pressure of the filling materials, they state, is much greater in the miflcU©
of the trench than at the sides. Moreover, there is some arching effect, oc
each side about 45-deg. down from the top of the pipe, and the com-
paratively horizontal top of the piije is more solid and unyieldinfi
than the side filling material. Hence the trench fill above the pip*'
receivea only a negligible support in ditches of ordinar>^ width from t b®
fill at the sides. For an extremely wide trench in proportion to th^
diameter, thie principle would no longer hold. Imperfections tn ^ti«
side filling and tamping probably decrease the applicability of * ^"'^
principle.

Most analytical discussion of the pressures in trenches lias b*?*?-^^
based upon the assumption of vertical sides. In many cases the sicJc*
of the trench witlen outward from its bottom, a condition which '^^^
investigated both anal>^ically and experimentally by Marston ^-^^
Anderson. An arching action apparently tiike^s place, they foii.0"'
between the sides of the trench and points at the ends of the C-<>P
quadrant of the pipe. Above the elevation of these 45-deg. points, ^^^**®
material along the sides settles less than that in the center of the tr€iB-^**"i
The investigations referred to led to the conclusion that in the^e we<l.
shaped trenches the proper width to substitute for B in tlic form.^-^*^
W ^ CwB"^ and to use as the width of the trench in Table lOU, m ^«^^
width at the height of the 45-deg. points on the pipe circumfenonoi?, i
a little below the top of the pipe.

The pressure of the backfdling is not the only load which may c<^
on the pipe, for the fresh fill may be called upon to support a he**
road roller or the wheels of a truck, and under some circumstances pil
paving materials, lumber or brick may be put directly on top of
backfilling for a considerable distance along its axis.

In order to determine the effect of such long excess I oaddMarstODP^
Anderson carried on an analytical and experimental investigati**'*^
They found that if this extra load, per unit of length pf ircach, in '***
garded as unity, the decimal part of it which is tranauiltted to Iho p*P^

^

^^H

^^^ SEWER PIPE 333 ^H

HHHhT difTereat dimensions, i& approximzitely that given In ^^M

Kuo, ^H

Biere the knut is iru posed by some short object like a road roller, the ^^^

Ibaf Ihe investigation by these engineers are not given by them with ^^^

HUtiveness, for it was found impracticable to test the theory ^^^

BRlch the analysis of such conditions wai$ based, Thii^ theory ^^^

bbout the same a^ that found t^ be correct in other work when ^^^

H experimentally, so the results in this case are of considerable vahie ^^H

1 if purely theoretical. Ap|>arently the proportion of the load ^^H

kni; tlie pipe depends on the ratio of the load along the trench to the ^^H

Ulthc trench and on the ratio of the lateral and longit udinal pressures ^^H

HBIokftUing. The maximum and minimum values of the propor- ^^H

5nh<* load reaching the pipe, are given in Table 111, The wide ^^^|

D of ihe liguros in this table t^hows clearly that tills particular portion ^^H

c investigation was not so directly applicable to practical problems ^^M

le n^t of it. ^^M

r«a*B 107- — ♦Vpproximate Safe Working Values of C in the ^^H

MAnsrroK and Anderson Trknch Prkssure Formula ^^|

Vftlwoa of C in W - Cwfl"

^^M

fctio frf 4rj,lij

Dxnip top aoil and

8jittirAtc5(]

Dump Saturn t«d

^^1

tovidib

«lry »tid wel BfiD«i

topBoit

y<^llow day yellow clay

H

0.5

0.46

0,47 0,47

0 48

10

GH5

0.8tt 0.88

0.90

^^^

15

I IS

1 21 1 25

1.27

^^^

2.0

I 47

1 51 1 56

1 62

^^^

10

1.70

1.77 1.83

L91

^^1

3.0

I 90

1 99

2.08

2, 19

^^1

IS

2 <)8 1

2.18

2.28

2.43

^^1

40

2 22

2.35

2 47

2.6,5

* ^^1

i.a

2 34

2.40

2.63

2.85

^^1

-5'^

2 45

2,61

2.78

3.02

^^1

W

2.54

2.72

2 90

3.18

^^1

V

2 (U

2 81

3.01

3.32

^^1

Pl*

2 68

2 89

3Jl

3 44

^^H

P ?(!

2 73

2.95

3.19

3 55

^^M

2,78

3.01

3 27

3 65

^^H

2.82

3.06

3.33

3.74

^^H

2 85

3.10

3 39

3 82

^^H

2 88

3.14

3 44

3.81J

^^^1

2 90

3,18

3 48

3.96

^^H

1 I'l i»

2.92 j

3.20

3 52

4.01

^^1

1 H^

2 i»5 1

3.25

3 58

4 n

^^1

1 fto

2 97

3.28

3 63

4 19

^^H

I I8<»

2 99

3 31

3.67

4 25

^^H

r

3 00

3.33

3 70

4 30

^^1

L_

3 01

3 :u

3 72

4 34

^^1

••*I«k tt ln*fl> it to the Inp o( th» pipe.

J

334

AMERICAN SEWERAGE PRACTICE

Table 108. — Propbrties of Ditch-fjlllvq Matekials
(.Marston and Anderson)

Material

Woight of' Ratio of Uteral Coef&oieQt of i Corftr-.rt-, .i
fiMlnK, lb. to vertical j friotioQ »ciiiot< iDt/rpfcl
p«tr cu, ftj f-arth preaaupwi I aJdea of trench | fnttiwi

Partly compacted damp
toi> soil

Saturated top soil . . * . .

Partly compacted damp
yellow clay , . , ,

Sat lira tfMl yellow cUy . .

Dry sand * , .

Wot SillKl. .

90
110

100
130
100
120

0.33

0.37

0.33
0.37
0.33
0 33

0.50

05$

0,40

I) 17

0.40

0 52

0.30

0 47

0 50

0 55

0,50

017

An example of the possible use of the table ia given by Muretoftl
An<!erson in a dijicimHion of the probable correctness cf
imprciiaion that more damage is doae to pi|>e with a small d'
than to those in deep trenches, and fliat more damage \& dune dii
tamping than is frequently considered probable by those who <
specifications for pipe. The maximum pressure P on the
resulting from the shock of a blow of a rammer^ is 2TF/f, when
weight in pounds of the rammer, F is the height in feet of the 1
rammer, and/ is the compression of the backfill under one blow of ^
rammer at the end of the tamping.

The data for the example of the use of the formula may be takonfro
a discussion by J. N. Hazlehurst (Jmir. Aa&ii* Eng* Soci,^ VoLl
Here the original "very thorough^' tamping was done with a^
rammer on a O-iii. clay cover, resulting in some cracking, while IftttfJ
use of a 30-lb. rammer on a 12-in. fill had no such result, U it is js
tluit very thorough tamping on a 6-in. cover is such as would prodiK
final compression / of 0,01 ft. under one blow^ and the hciijht d I
was 0.5 ft., then with a 40-lb. rammer P == 4000 lb. If the numDerl
a face width of 0.67 ft., then the ratio of its fall to its width // ^t ^^^
The percentage of P reaching the pipe would be, from Table 1 1 i, &lKiui|
Hence about 2500 lb. would be directly transmitted to an ** X ■
area of pipe, and the total shock load would be somewbero betwrefi i
and 40OO lb. With the lightor rammer, / would prolmbly b^
larger, say 0,015 ft,^ because the cover was 1 ft, instead of 0,51
aame method of computation as in the first case shows that ihd.j
on the 8 X 8-in, area would be about 800 lb, Tht? cotti^
the opinion occasionally expressed regarding the Ui*e of a rathefi
cover and light rammer in the lower part of the trench is confirmed by^
analytical method of investigation.

If sheeting is left in the trench, but the rangers are
friction between the backfill and the sidea of the trench

SEWERPIPE 335 ^^1

aad the load on the pipe increased* The Marston and " ^^^|

H.nd«'rH(>tt

experiment 8 indicate that this increase is from 8 to 15 per ^^^|

Btnt. and the experiments by F, A, Barbour {Jour, Asm* Euq, Sor^,^ ^^^H

H897) confinn this conchiisioii. If the rangers are left in place, tlie load ^^^|

Hrnnbg on

the pipes would prolmbly be about the same m in uns^heetcd ^^^H

Btreatihes, according to both theory and experiment by Barbour* ^^^|

i Tauli 109

«— Approximate Maximum Loads, xk Pocndb Per Linear ^^^H

H Foot, on Pipe in TftExcuEs, Imposed by Common Fueling ^^^H

w

Materials. (Marston and Anderson),

^H

Breadth of ditch at top of pip©

H

|kil»

I f t, ) 2 rt, I 3 ft. ( 4 ft. 1 5 rt

I ft. 1 2 ft. 1 3 ft. ( 4 ft. 1 5 ft.

partly oornpftctod damp top 0OU:

enturated top toil; 110 lb. per cubi<^

00 lb. per cubte foot

foot

^H

a a

130

310

490

670

»30

170

380

600

820

1.020

4fL

200

630

880

1,230

1,680

260

670

1,000

1,510

^ 1.960

^^^^^k

«lt

330

690

l.KHi

IJOO

2.230

310

870

1,500

2,140

2,780

^^^^^k

Sit

260

800 1 1.430

2J20

2,700

340

1,030

1,830

2.600

3,510

^^^^^k

JO 11.

a«o

880 ' 1,G40

2,450

3,290

350

1.150

2,100

3,120

4,160

H

Pry *

»«ti<t: KKI lb. per eubk foot ( ^Sfttiif«t«d Mbd; 120 lb. p«r eubic fmit

lit

ISO

340

650

740

030

180

410

65C

800

1.110

itt

220

hm

070

1,360

1J50

270

710

1,170

1.640

2,1WJ

^^^^^

• ft

2110

7m

1,320

1,800

2.480

310

010

1,590

2.270

2.970

^^^^^

ItL

2d0

§tK)

1,690

2,3.'>0

3,100

340

1,070

1,910

2,820

3.720

^^^^^

lurt

2W)

080

1.820

2,720

3,660

350

1.180

2,180

3,260

4.380

^^^^^k

^fe

Utt.

dm

1,040

2,0<K)

3,050

4,150

300

1.250

2.4€0

3.650

4,980

^^^^^k

^m

iHt

300

1,000

2,140

3,320

4.680

360

1.310

2,570

3.090

5,49*J 1

^^^^^k

^P

WH

aoo

M30

2,2tiO

3,550

4,050

360

1.350

2,710

4,260

5.940

^^^^H

W

uh

aoo

M50

2,350

3,740

5,280

360

1,380

2.820

4,490

0.330

^^^^H

1

«ti

300

1.170

2,430

3,020

5,550

360

1.400

2.910

4.700

6,660

^^^^H

I

sri

300

1,180

2,4!*0

4,060

5,800

360

1.420

2.080

4,880

6,900

^^^^^

K

Mk

3(10

l.ltfO

2,540

4,180

6,030

300

1.430

3.0.W

6,010

7,230

^^^^1

^k

li(i

3tfl

1.300

2.570

4.290

6,310

360

1,440

3,090

5,150

7,460

^^^^1

^m I

«ft

300

1.200

2.000

4,370

0,300

360

1,440

3,120

5,240

7,670

^^^^^k

^H^

: !■-•'

2.0:*0 ' 4,4.50

6.530

360

1.440

3,150

6.340

7.830

^1

i< uhI (l«mp yeUow >Saturat«l yellow cUy; 130

lb. pi«f

H

► per eubio foot cubic foot |

^1

H

550

760

(»30

210

470

730

1,000

1,240

^B

4U

'^<f\

njo

l.OIO

1. 400

1,S00

340 1

840

1.330

1,870

2.370

^^^^1

^1

lit

300

830

l.4(u>

t,!>W

2,590

430

1.140

1,900

2.630

3.410

^^^^1

^m

1 n

330

.H.n,

T -M,

■' '^

3.2S0

490

1.380

2,360

3.360 4.400

^^^^1

H

3S0

1

■.,

3,S80

620

1,570

2,760

3.980

5.270

^^^^1

H

SdO

l.:"

_<\

.4,450

540 1 1,730

3.100

4, WW

O.O.V)

^^^^^

H

370

I*21K»

2.4 ru

l^,i*m

4,950

660 1 1,860

3,410

6,0.50

6,760

^^^^^

H

370

1.33«1

2.570

3.050

5.400

670 1 1,040 ,

3,000

5.510

7.440

^^^^1

H

380

1,380

2,710

4,210

5.810

670

2.020

3,880

5,93*1

8.060

^^^^1

^1

sm

1,4 Kl

2,»»0 : 4.45r>

6.160

580

2,000

4,070

0.280

8.610 1 ^^^m

^L

_..

■ ■ ■ .oi

6.600

hm

2.140

4,240

6,61"

9,130 I ^^^H

^H

1'

> 6.800

bm 2.180

4,380

6.910

9,fi00 ^H

^H

1'

> isym

4,600

T.tflO

to.oto 1 ^^^H

^H

1'

1 7,310

4.610

7,380

10,430 I ^^H

^H

■ '•

1 ' 7.5rMl 4.700 7.6W

l0,78O 1 ^^^B

1

'TVivtv«

336

AMERICAN SEWERAGE PRACTICE

Table 110. — Proportion of Long Superficial Loads on Back-
fillinq which reaches the pipe in trenches with different
Ratios of Depth to Width at Top of Pipe (Marston
AND Anderson)

Ratio of depth

Sand and damp

Saturated

Damp yellow

SatontMi

to width

top soil

top soil

ohiy

yellow cUy

0.0

1.00

1.00

1.00

1.00

0.5

0.85

0.86

0.88

0.89

1.0

0.72

0.75

0.77

0.80

1.5

0.61

0.64

0.67

0.72

2.0

0.52

0.55

0.59

0.64

2.5

0.44

0.48

0.52

0.57

3.0

0.37

0.41

0.45

0.51

4.0

0.27

0.31

0.35

0.41

5.0

0.19

0.23

0.27

0.33

6.0

0.14

0.17

0.20

0.26

8.0

0.07

0.09

0.12

0.17

10.0

0.04

0.05

0.07

0.11

NaUe. — Curves based on this table are given in Fig. 181.

Table 111. — Proportion

which Reaches the

of Depth to

of Short Superficial Loads on BACKnLU.\o
Pipe in Trenches with Different Ratios
Width (Marston and Anderson)

Rotio of

Sand and damp

Saturated

Damp yellow

Saturated

depth to
width

~0.0

top
Mux.
1.00

soil

Top soil

clay

yellow cUj

Min.

Max. 1 Min.

Max.

Min.

Max.

I^Iia

1.00

1.00 i 1.00

1.00

1.00

1.00

1.00

0.5

0.77

0.12

0.78 0.13

0.79

0.13

0.81

0.13

1.0

0.59

0.02

0.61

0.02

0.63

0.02

0.66

0.02

1.5

0.46

0.48

0.51

. 0.54

2 0

0.35

0.38

0.40

0.44

2.5

0.27

0.29

0.32

0.35

3.0

0.21 '

0.23

0.25

0.29' 1

4.0

0.12

0.14

0.16

0.19

5.0

0.07

0.09

0.10

0.13

6.0

0.04 1

0.05

0.06

0.08 j

8.0
10.0

0.02

0.02
0.01

0.03
0.01

0.04

0.01

0.02

Note. — Curves baaed on this tabic are given in Fig. 181.

The experimental and theoretical work which has been referred to at
length relates to new backfilling. There is abundant evidence tbM
in many cases the maximum load on the sewer pipe is not importJ
until the first heavy rain saturate^s the trench and possibly puts the
pipe under internal pressure. Reports from engineers in Iowa confinn
statements made at an earlier date by engineers with experience in
eastern states, that lines of sewer pipe sometimes crack long after

I

SEWER PIPE

337

licy wertj put in place. Such evidence indicates, therefore, that in
Onmdering the necessary strength of pipe the values of the trench
sures* determijied by Marston and Anderson may probably be
ccepted m reasonably accurate, particularly in view of their careful
Bvestigation of lines of drains and sewers in Iowa which have not failed,
ftvemge factor of safety in these cose^ being about 1.65, estimated
[ the average trench pressures atid pipe strengths determined by the
ligation.

STRENGTH OF PIPE

The theoretical analysis of the streng;tli of pipe under external loads

that of thin elastic rings, and t^kes various forms under different

sumptions regarding the loading. An explanation of it is given by

A. N. Talbot, in Bulletin 22 of the Engineering Experiment

itiOQ of the University of Illinois, in which he reports tests of castr

an and reinforced concrete culvert pipe. Marston and Anderson

ive given the results of an analysis in which the weight of the pipe, as

that of the backfilling, is taken into consideration. For all

tical purposes, three aiisumed conditions of loading will be sufii-

at to guide the engineer, viz., concentrated loads at the top and

ttom of the vertical tliameter of the pi^ie, uniformly distributed

tical loads above and below the horizontal diameter, and uniformly

stributod loads on the top quarter and bottom quarter of the circum-

rence of the pipe.

The bending moment at the top and bottom of a pipe of diameter d

(\AS9Qtl under a concentrated load, (?; 0.0(325 HV/ under a total

liiiformly distributed load, W; 0.0S4DWd under a total load, W,

Birihuted over the top fourth of the circumference and with the

ipe supported on its bottom quarter circumference.

The bending moments at the ends of the horizontal diameters under

conditions of loading are 0.09 IQd, 0,0625 fFd and O.QJlWd,

spectively.

Pipe have l>eon tested under all three loadings. Some testing by con-

entrated loading is carried on annually by the Bureau of Sewers of

rooklyn^ N. Y. The test** at the Iowa Engineering Experiment

tttion are made by lomiing a fourth of the pipe's circumference, aa

loading seemed to Marston and Anderson to reproduce better than

ay other the conditions in a backfilled trench. The leading published

Ejllections of American test resultis are those of F. A* Barbour in J<ruT,

i»90C* Eng* Socs,^ Dec. 1897, Marston and Anderson in Bulletin 31,

ra Engineering Experiment Station, and M. A. Howe, in Jour*

lB$0C* Eng. Soc8,f June, 1891, the last being summarized in Table 112.

In 1890 tests were made at the Rose Polytechnic Institute, Terre

aute, Ind., by Prof. M. A. Howe, on pipe from 15 manufacturers.

23

338

AMERICAN SEWERAGE PRACTICE

"A

s

00
CO

s

eo

s

o

i

CO

CO

s

r^

s

s

CO

{5

9

g^

r^

s

CO

CO

O

o o

S5«

s

CO

8

H

CO »o -^
t>- »o '<*

CO -^ t*

o

CO

Od

s

s

o

; o o 00
CO "«*< »o

1^ C^ CO

C^ CO CO

c^

-«»<

o

o

8

03 ^

11

00 •^
lO 00

c3 is 5
« o -g

CO

o

»o

s

6

55

- ^

c

c3 —
bC

6:2

.1 o

■S S'

J^ 00 .

S.

a

•3 ^.S

.2 *-

sr

s.

a -'

SEWER PIPE

339

br it»ults were published in the Journal of theAssodaticm of Engineering

Wietm^ June, 1891, and are sumnmrizcKi in Table 112. Three different

t'Uiodit were used in making the hydrostatic tests. The first and

ond caused a pressure to be exerted upon the ends ol the pipe, while in

lo pressure was brought to bear on the ends, which were closed

Ikt cups. The teats showed consbtently that the third

neiliod gave higher results, and it was considered more reliable by Prof.

^uwft. The other methods gave lower results because of stresses due

end pressure. The averages of tensile strengths for the different

I of pipe varied from 265.6 to lOSLS lb. per square inch» while

bepaeral average of all results was 600.4 lb. The minimum recorded

[ life pressure was 12 lb. per square inch; the minimum tensile strength

|ll^lh. per square inch; and the maximum tensile strength 1S25 lb.»

lof thetie being for a single test.

'*ln the hydrusUitic tests the color of the fracture, with hardly an oxcep-
(flhe criterion of strength, each class having its particular co\m
ag to the greatest strength/'

Ttfu 113,— Mean Minimfm and Maximum and Average Resistance

TO IXTERKAL PRESSURE OF GERMAN VlTRIFlED ClAY PiPE

iBurcharU and Stock in Ettg. Ri

c„ Aug. 18,

1900)

thickDf^

Number
o( teata

Intern&l witt«r pre«ure in
iitmosphcrn

UUi«mte
Avermse tud-

tpo until! per
square inch)

Average

miikiiDiiin

AvQrac<}

inaiimuoi

Tot«l

«

0.72

$

24.0

28.0

26.1

490

8

0.80

3^

Ifi.O

18.4

10.3

490

4

0.68

11

0.2

25.2

20.1

830

•1

0<80

23

8.3

24.5

17.2

850

1

0.03

13

14.5

24.2

17.9

1.120

U

0 W

a

6.0

8.0

7,0

600

U

I.(H

19

8.7

16.0

11.9

920

lij

t.i:i

2

9-4

9.7

9.6

910

11

1.28

8

7.1

12.0

0.3

920

»

t.44

4

9,0

12.2

10.6

1.(110

u

1 72

7

6.3

8.6

7,2

720

a

l.M

i

7.1

10.2

8,7

910

;o

1 90

H

5 4

9.0

7.7

l.U'O

\ -

1 13.9

S/iO

^^— plpra of 0.lt2 jind 0,64 in. diAtneter. One a tmosp hero — 14-607 tb. por aquaro
'•*^«111> ft, of vnu-t. Mif»imura prnnurc, 6.3 aim.- 180 ft. wal«r«78 lb. p«r square

• M^ at the Royal Testing Laboratory in Berlin, by

Me> .iful Stock, ami their retiult^ for 1890-1904 inclusive

' gu'CTi III HnQifwcring Record^ Auguist 18, 1906. The mean mini-

i maxtiDum &nd average valuer for resistance against internal

340

AMERICAN SEWERAGE PRACTICE

pressure are given in Table 113. The average water pressure wis
13.9 atmospheres or 204 lb. per square inch, and the average ulti-
mate tensile strength 650 lb. per square inch. The minimum pres-
sure was 5.3 atmospheres, equivalent to 78 lb. per square inch, or
183 ft. head of water. These results from German pipe are highv
than those obtained by Prof. Howe from American pipe.

Although vitrified pipe may be manufactured of such strengtii u to
stand hydrostatic pressure of 100 lb. per square inch, or even more,
it is a question whether the joints now in use will be equally stronf.
There are few published data on this subject. The tests made by
Prof. Howe at the Rose Polytechnic Institute on cement joints are
summarized in Table 114. These tests are rather imsatisfactorj,
because of the wide range of the results. It would appear, however,
that the pressure which the joints withstood is much less than the pres-
sure which the pipe was capable of holding. It is rather hard to under-
stand why the pipe broke in several cases instead of the joints failing,
but this may be partly due to the methods of testing.

Table 114.— Hydrostatic

Tests

OF Well-made Natural Cbmeht

Joints for Vitrified Clay Pipe — (Hows)

Nominal
internal
diameter

Average
thickness
of cement

Average
depth of
cement

Propor-
tions
used for

Age of
joint

Test
method

Pressure

sure,
(pounds

Remarks

of pipe
(inches)

joint
(inches)

joint
(inches)

cement

joint
(inches)

(days)

em-
ployed

per

square

inch)

6

0.20

1.40

neat

33

2

148.0

Pipe broktf.

6

0.44

1.65

1 :2

14

2

none

Joint failed.

G

0.34

1.03

neat

21

3

25.0

Joint failed.

6

0.34

1.76

neat

21

3

17.5

Pipe broke.

6

0.30

1.80

1:1

6

3

25.3

Joint failed.

8.

0.35

1.50

neat

41

2

50.0

Pipes broke.

8

0.28

1.70

• neat

16

1

50.0

Pipes broke.

8

0.50

1.80

neat

21

3

none

Joint failed.

8

0.27

1.78

neat

21

3

17.6

Joint failed.

8

0.56

1.90

1 :1

6

3

12.0

Joint failed.

10

0.35

1.40

neat

21

1

none

Pipe broke.

12

1.50

4.50

neat

33

3

116.0

Joint leaked

12

0.25

1.75

neat

2,

3

6.0

Joint failed.

12

0.44

1.85

neat

28

3

17.6

Joint faUed

12

0.50

1.83

neat

21

3

12.0

Pipe broke.

12

0.24

3 05

noat

6

3

37 6

Pipe broke.

Mr. Barbour stated, as a result of his tests, that the thickneffl <rf
pipe when stressed to its ultimate strength was

.J>3

SEWER PIPE

341

ifthe thickness in inches, p the pressure in pounds per linear
^rfthe internal diameter in inches, and c a constant taken empirically

T Talbot deduced his formuliis for thickness from the exprea-
thtr maximum bonding moments. These are t = QM7i\\/'(Qd/f)
meentruted vertical loading, and i — Q,25\/{^Wd/f) for a unifoniiiy
buted vertical load, where / is the unit stress in the remotest

krston and Anderson give for the 90 deg. top loading and 90 deg.
m support t = \/X0.5Wd/J),

e modulus of rupture in many lots of sewer pipe tested by Marston
ranged from 910 to 1940 lb. per square inch for single-strength
ttO to 1720 lb, for double-strength pipe. In these tests, as in those
P. Johnson (Eng. News, March 19, 18S6), it is apparent that the
llus of rupture so obuuned is two or three times the tensile strength
J materiaL The same is true of the results of tests of small cement
in which the modulus of rupture was as high as lOOO lb. per square
In many cases.

distance of Cast-iron Pipe to Internal Pressure*— The standard
locations of the New England Water Works ^-Issociation, adopted
W)2, were based primarily upon the practice of the Metropolitan
Works of Boston* The thickness of the pipe was determined

rmula
I* ^^—+0.25, in which
t ^ thickness in inches,

p« static pressure in pounds per square inch,
p'» pressure duo to water hammer in pounds per square inch,
fB internal radius of pipe, in inches,
3!iD0 => \ tensile strength of oast iron, taken to be 10,500 lb. per square

inch,
0,25 ^allowance for deterioration by corrosion and other causes.

Values given to ;/ as follows:

Diameter of pipe

^4,6, Hand 10 in.

12iiDd 14 in

Ifl and IB in

20 in,

21 ....

m m .
42 to 60 Ml

p* in pounds
per aq. in.
120
110
UX>

00

85

80

75

70

It will be noted that the allowance for water hammer ia a very
kWiLlial 000.

342

AMERICAN SEWERAGE PRACTICE

■panod 'q^Saai

|o waujionu.

spanod *qi8aai g ^ <

spanod *q%9n9i

saqaai *n^q«
|0 Bsaasfonix

531

d d <

§11

d d d

epanod 'q^Saoi g o
jad 9q9i9M « '•'

floqaai 'naqs
|0 nansfanix

spanod *qtSNiai

|o Bsaniiafqx

spanod *i{)8aai
aad «q8iaj|^

JO ssaasfoiqx

spanod 'q^9ad|
Q , jad YqSiaAi

saqaai 'ipqs
JO ssaa^dtqx

(O 00

C4 Q <

d d <

8 0 O O P O Q Q
O ^ 3 M •* O O

t-4 ^ t-4 04

SSiSS

lO o
to 00

o o o o
31 '-' -^ -^
O CO o o

i d d

O O ^ -H

S8§S

O M <<• t«

: spanod '^'^»x^9\ ^ |
aad )q8idAi I

2ggg

04 «-« W «

S3||
C) lO ^ ob

•4 N CO •*

JO ssaujiJiqj. © d d d

o c o o

spanod 'qiauai
jdd "^qltio^^

saqani 'naqs
JO esoujfoiqx

•c 36 5 ?5

X o w to

, c o

1 CO t*

^ « ^ ^ C4 CO ^

CO r>. o CO

ir» L~ :^ e5

epunod *m8ooi c c j
< Jdd jqaio VI N CO

1' '—

:= eoqoat *n'*M^
"^ JO esoajfoiqx

5 X :: ^ ;

9 S !

adid JO
'ani|p |vuiuioj^

'' 6 d

© CO t-*; t>.

^ ^ Ob

e t^ r*

c d d

M ^ « »

oieo^o oooeoo

0,HrH^4 vHvHvHM

iQ loiooio oioe^o

O ^ O) CO O) 1^ Oi

cJcieoto ©oddco

iSSS

oo^^ ^^.-.^

w o> §
« t-^ d ^

COO'^ •-••^^^

8288

ecoo ^ ^ ^ ^

SS2I

0» — »q (
^ fO t> cc

g^gS 992S

^ SEWER PIPE

343 ^1

^H ThP!*c spectficsttons also require a hydrostatic test, under

which ^^1

^B* t.Iie pressures to whkh the different size^ and clashed of pipe shall ba ^^|

^^kaJL>jticted'* are as follows:

■

^^^^ (Page 95, Journ. N, E, W, W. As^n., 1902)

■

^^^^^ ClasH A pipe, 150 ib. per square inch.

^^^^^^^^ Class B pipe, 200 tb. per ^uure inch.

^^1

^^^^^^^H Class C pipe, 2<50 lb. per square mch.

^^1

^^^^^^^B Cl&^ D pipe, 300 lb. per square inch.

^^1

^^^^^^^B CiiL88 E pipe, 350 lb. per square inch.

^^1

^^^^^^H Class F pipe, 40O lb, per square inch.

■

P MT'tit^ !?pocification3 do not indicate the conditions under which the ^^|

^^diif Cerent classes of pipe can be used, this being left to the judgment of ^H

^^Bio eo^neer, aa being dependent not only upon the pipe pressures to ^|

^^P^ met, but abo the environment of the pipe* It may be adtled

y how* ^^1

^^pv<er, that Dexter Brackett, Chief Engineer of the Metropolitan

Water ^H

^^H^Hfe who waa largely responsible for the development of this standard, ^^|

^^^^BHIthat in the practice of the Metropolitan Water Board,

which ^^^

^^^H TxaLB Ua— Standard Weiohtb peh Foot or Straight Pipe, ^H

^^^H Exclusive} of Sockets

^^1

P (New Englmod Wator-workB A»sociation)

^^1

^ ^

1

11

m

ll

1

11^

h

1 11^ li

J

■

^^ o

il^

^"^

U

ll-s

l«

^1^1'^

1'

"^

fci-

■

U.Sft

12

c

70.67

18

E

148.4

30

F

602.0

i c

16 70

12

D

75,30

18

F

159.0

42

A

368.4

,^^H

s

10 92

12

E

81.99

20

A

121,9

42

B

422 I

^^H

o

U.89

12

P

80.77

20 '

B

133.7

42

C

481.1

^^H

I

90,10

12

G

91.61

20 !

C

147.0

42

D

68K 0

^^H

X

81 ao

12

H 00.22 1

20

D

101.4

42

E

OWJ.O i

^^H

A

24 3a

14

A

70.86

20 1

E

17.5.0

42

F

064.4

^^H

c

2tt.T2

14

B

82.41

20

F

189.5

48

A

459.3

^^H

E

n.m

14

C

87,97

24

A

153.0

48

a

630.2 '

^^H

o

%tAQ

14

B

94,85

24

B

174.4

48

c

008.0

^^H

t

34, 7«

14

E

102,73

24

C

ioo.:i

48

D

678.9

'^^H

A

»S.&S

14

F

109.70

24

D ,

215 3

48

E

758,6

^^H

C

40.38

14

0

US. 24

24

E ,

234.5

48

P

829 4

^^H

1 ^

E

44 33

14

H

120 74

24

F

263 6

54

A

6.7tl 8

^^H

I *

0

49.05

10

A

90.08

ao

A

215.3

54

B

050.3

^^H

1 •

1

53.02

10

B

98.96

30

B

244.8

64

C 1

749 5

^^H

I HI

A

49.04

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C

100,9

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C

277.7

64

D

8;i(l 9

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h2.m

10

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114,8

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D

307 3

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940 9

^^H

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125,5

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^

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1042,7

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67 94

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laas

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F

367 6

00

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004,0

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K

A.1 M

10

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141 4

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287 0

oo

B

782.3

^^H

k I ^"^

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00 Al

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140,3

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C

9H.6

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m \ »o

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IS

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Ot 14

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60

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1280 0

^^H

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ft5 93

IB

n

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1

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J

344

AMERICAN SEWERAGE PRACTICE

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346

AMERICAN SEWERAGE PRACTICE

supplies water to Boston and other cities and towns witliin
of ten miles, Class A pipe of the N, E. Water Worka A»sn. stao
specifications (Tables 115 and 1 16) has been used for static heads j
ft., Clasd 13 for 100 ft., etc., each class advancing about 50 ft.

In the case of works suppl^dng smaller cities or towns, where extj
tions in the streets are of less frequent occurrence, these classes i
have been used under much heavier pressures than those in accord
the Boston practice ^ lO-in. Class A pipe having been used succ
under static pressures as high m 125 lb. The past practice of i
engineers in this respect^ covering a period of from 20 to 30 yeani
successful experience with the pipes of the stated weights, is shown
Table 117.

In sewerage work the lightest weight classes of ihe New EnglaE
Water Works Asscjciation st4indard specififation pipe are genera!
use^, except in such cases as may involve very hea\'y traffic loads ar
pressures, and probabiiity of future displacement from one cau^c •
another.

In 190iS, tlie American Water Works Association adopted somewhj
similar specifications for ca-st-iron pipe, but with radically diff«ll
weights for the different classes, as shown in Table 118.

n

MANUFACTURE OF CLAY AND CEMENT PIPE

The methods of manufacturing cement and \'itrified pipe differ -
radically as do the properties of t hese two classes of sewer materials, TI
distinction between the two is so complete, in fact, that the attenij
to lay down standard requirements applicable to both alike has tk*
yet Vjeen successful, and the most satisfactory results have bceu obti
when specifications are prepared for each class of pipe, indepcndcii
the other, in such a way as to utilize to the fulfthe useful projjerti
the materials and technical procas^ses employed in the industry.

Vitrified Clay Pipe* — Vitrified salt^glazed pipe are made froml
and shidcs, only a small part of these raw materials found in nntur«*|
fit for the purpose. They are prepared in various ways, accordi|
their source, for the press which forms them, the methmls retjuir
shale obviously being different from those for clay. This stage
manufacturing process is somewhat important because some
surface pimpling on salt-glazed pipe is apjiarently due to the \mi
preparation of the shale or clay as well as to the heat treatment,
Aubrey reported in Trans. Am, Ceramic Soc., 1907, tliat by ]
clay through a 16-mesh screen he was able to effect a ni ' * lu
the pimpling as compared with the results when an ^
used. A 29-me^h screen was little more effective than a ib-nns^l
also found that the pimples were appar* ntiv rruw.*.! hv tK<

SEWER PIPE

347

fusing, bubbling and swelling of small particles of shale, lying close to

I the mrfaeti of the pipe, although other makent reported that the pimples

' »m their product seemeti to be due to the oxidation of the iron in the clay

during the burning. The general opinion of those discussing the subject

4t that time was that pimples could be avoided to a large extent by ut^-

tentiou Ui temperature regulation during the burning and by glazmgonly

when tho flame had become perfectly clear..

The prepared clay is placed in the hopper of a press, this hopper being

1 Af^rtifider 24 in. or so in diameter, with tlie wall drawn in at the bottom

I Id tho sthape of the outside of the bell of a pipe. A rod is held in

10
U

24

3L6

n

/

A - Eastern Qay Oocdi Co. Atr^, Ohio,

C • Pbrffand^rttnewarB Ca Porthnd. Ma

I'Emii&He^^rdFimBficHCcr 5t Louts, Mo.
G'fi, Sfw¥€m 'Jons Co.- Maion, 6<r,

-^

"^^

^^

^^^'

>

^"^

^

J

V

>

V"

ly

r

'K

A

^

f

4

y

y>

r

y.

\i

&^'

^

/

^ ^_

^/

[^

d^

^

I.

t/'-

W'

V

,.rS

^4

■3^-

t f ' 1

^ ' 1

^

f^

Listed TwicKHta* ^

OF

y

V

w

\

i

^

^

■ ital IMMUAnu AMD

VJTRIflEC

werPipe.

'^

Him

~

r

~ f)^.,kU ^*^m^*4* ^^

^

■

1 1

1 1

1 \

o.e

%\

0 t 4 & e 10 IE H 16 Ift 20 22 24 Z^ 2B 30 32 34 3^
Diameter of Pipe in Inches.
•ftfl. 122,— listed thickneBB of standard and double-etrengtb vitrified

sewer pipe.

*a Uwj axi« of the cylinder by a spider and to its bottom is attached
I • *nr© die* or bell, at the elevation where the wall of the cylinder is
<tiim in* An annular spuce as thick ad the green sheU of the pipe is left
in this way in the bottom of the hopper, and the pipe is formed by
P««in« Uic clay through thia space, the inside of the bolJ bein^ formed
[J7 ^ mold on the top of a moving platform on which tho green pipe ia
*<l, *rhc thickness of straight and curved pipe id given in Fig. 122
Table 1H>.

I pipe are ganorally seasoned under cover for some tirne^ to allow
eh water tc j evaporate aa will naturally pass off in this way* The

348

AMERICAN SEWERAGE PRACTICE

Table 119.

Dimensions of Curved Vitrified

Clay Pipe

w

a— ->J

k

« 1

h

e

d

«

/

k

J^ndhll

in.

deg.

min.

in.

in.

in.

in.

in.

in.

in.

ft

6

28

2i

8i

94

74

\

24

10

8

28

21

lOi

114

94

\

24

10

9

28

2}

111

124

101

H

24

10

10

28

2i

121

13J

Hi

i

24

10

12

28

3

15

16

14

1

24

10

15

28

3

184

194

174

li

24

10

18

28

3i

22

23

21

U

24

10

20

28

3§

244

254

234

li

24

10

24

28

4

29

30

28

H

2

24

10

30

28

4i

36

37

35

H

2i

24

10

36

11

28

5

424

434

414

H

2\

24

10

6

5

44

2i

84

94

74

A

\

24

20

8

5

44

2!

104 ■

114

94

A

i

24

20

9

5

44

2!

111

124

101

A

H

24

20

10

5

44

2i

12i

13J

iii

A

1

24

20

12

5

44

3

15

16

14

A

1

24

20

15

5

44

3

184

194

174

A

li

24

20

18

5

44

31

22

23

21

A

li

24

20

20

5

44

3i

244

251

23}

A

li

24

20

24

5

4A

4

29

30

28

A

2

24

20

30

5

44

4i

36

37

35

A

2i

24

20

36

5

44

5

424

434

414' A

2i

24

20 _

pipe are then placed in the kiln, work requiring considerable skill based
on long experience in order to reduce the number of inferior pipe to «
minimum. The burning of a kiln is a slow process and it is during tto
that most of the defects of sewer pipe appear. The irregular zigzag "&*
cracks," usually circumferential, are apparently caused by the dir^rt
play of either hot gases or cool air on the surface of the pipe where they
are found. Other cracks appear as a network over a large part of th*
surface of a pipe and are usually attributed to heating the pipe toorapidy
in the early stages of the burning. In passing through the die, there
seems to be a tendency for the clay to become laminated, and when *
network of these so-called *' water cracks" i& formed, they are "OS^

SEWBH PIPB

349

eirtcnd deepl}' into the shell, on account of this lamimition, un-
pipe are large and the heating is conducted vigorously from tlie
^ of the buraiug, in which case the gwaes in the clay may be
isd so rapid ly that large blisters form on the surface of the pipe
w lengths inay have flakes blown from their surface.
cation brings these defects out more prominently than they
before that stage in the process is reached, because wiUi vitrifica-
corne^ a tendency toward ishrinkage,
,cks are the main defects in vitrified sewer pipe. When
have little appreciable effect on their strength, and for
n^ Emil Kuichling^ after a careful study of pipe making and the
,t» for satisfactory service in sewers, recommended in widely
tficatioriB for use at Rochester^ that one fire crack not more
li I 3 in. wi«le should not cause the rejection of a length of pipe,
first, if it went through the shell » that it waa not over 2 in,
len at the spigot or 1 in. long at the bell; second, if it went through
f>-t birds of the thickness of the pipe, that it wa^ not over 4 in,
rd, if it went through only one-half of the thickness of the
?!1, that it was not over ti in. long; fourth, if it w^ent through less than
Kvhalf of the thickness of the shell, that it was not over Sin. long; fifth,
it waa A transverse crack, that it was not longer than one-sixth of the
Omnference of the pipe. Two or more fire cracks of any of these
B dftttttk in one length of pipe wasoause for rejection. Irregular lumps
unbroken blisters on the inside of a pipe, when not more than 1/4
and I or 2 in, in diameter, were not considered a sufficient obstacle
of the sewage to justify rejecting a pipe on which theyap-
, the rule beting to reject a pipe or special having on its inner surface
o blister or flake thicker than one^ixth the standard thickness
ibell and longer than one-twelfth of the inner circumference of
'<> reject it anyway if the pipe couJd not be laid so as to
r on top. So far as warping during burning was con-
Kujchling's specifications required the bells to leave without
ivg a »imco of at least 1 /8 in. around a spigot inserted in it. At
IK) piT cent, of all pipe leas than 12 in^ in diameter had to be
itudly circular and at least 40 per cent, of thoi*e 12 in. or more in
In no case must the long diameter of an aocejjted pipe be
§ or 7 per cent, longer than the short diameter.
[MS of the bnll of sewer pipe was investigated in the winter of
12, by the Institution of Municipal and County Engineers of
' h appoinicd a Standardization Committee to de-
) ijo of socket. The great objection to the old type,
f T. nor Df the bell parallel to the shell of the pipe, is that the
' ^ !wa>'B center the spigot of the pipe they were laying
11 of th<t pipe just laid, therefore there was a tendency

IfLowi

^ha|M

350

AMERICAN SEWERAGE PRACTICE

of the spigot to be low in the bell thus producmg a roughness at euch
joint. To overcome this objection, a type of socket was recommended
by the committee which has walls flaring out like the sides of a fanuci,
so thfit when the spigot of a pipe ia introduce*] in the bell of the preced-
ing pipe laid, the two sections are lined up without any attention from
the workmen and a satisfactory' surface is obtained along the Invert.
The comrailtee was of the opinion that this form of joint would aim
prove de^siral^le on account of the smaller amount of material which wa«
necessar>' to Ell the joint space, and the reduction of the chance tliat
something might enter the pipe during the making of the joint.

Cement Pipe* — The amount of capital required to put up a smitU pbint
for making cement tile and pipe is so mtxlerate that a large number of
these little works have been built. Owing mainly to hick of akitl,
working capital, or both, much inferior pipe has been protluced in these
small plants, and this poor product has prejudiced many engineers
against all cement pipe* There are a number of large cement pipe
plants^ however, each representing a considerable investment and «ome
managed by technically educated engineers, where pipe of fairly uni-
form gra<ie are produced. These works arc ready at aJl timed to
submit their product to comprehensive te^ts like those adopted about
191 1 by the Iowa Society of Engineers and other technical and drainage
organizations in that state. The existence of widely recognized Ktjtndard
requirements of a fair yet rigid character and frequent t^estfi to insure
the rejection of products not meeting these specific at ions are necessary
factors in any satisfactory condition of the cement pipe industry ; with-
out them a product having so little uniformity aa to be positi\'dy
unreliable is likely to flood the market.

The materials for cement pipe must be of high grade, partieulj
when the pipe are made from a dry mix. Cement which will pass tl
specifications of the American Society for Testing Materials will prove
satisfactory for pipe manufacture in most cases, althotigh there i* a
very slight chance that a brand may be found occasionally which will
not work as well with local sand as other brands which test no better.
The sand and gravel or broken stone, which must be clean, arr
made up, in the best plants, in proportions which give appa
a 1 to 4 mix for shees up to 20 in. to be used under he^s not exceeciuii^
15 ft. There is a great variation, however, in this practice, and a 1 to
3 mix is, perhaps, more customarj^ in pipe above 20 in* The indit'idaiil
preferences of purchasers, as well as manufacturers, h
anything like uniformity being reached, mid this is also
of a small amount of hydrated lime in tlie mix, which was widely pne-
tised in Southern California about IIKK), ^ - -- * -v^ a- > v*
series of tests was made by GeorRe P, Du
Northwestern States Portland C»

SEWER FIFE

351

for pipe, and tbe results le4 Ixim to recommend for the tine aggregate a
iDAtmsl 90 graded that not more than 10 per cent, would remain on a
lO-BienH sieve, nor rnorc than 30 per cent, pass a SO-mesh sieve. The
pracliiae ncg^nling the gravel or broken stone forming the coarse aggre-
gate seams to be, in the ease of tile, to require all tliijs material which is
tiled to be retained on a screen with 1 /4-in. holea and to be not
giic»re IhAu half the thickness of the wall of the pipe. Small pipe up to
abotit 10 in. in diameter are preferably made without any coarse aggre-
|pae« for experience shows that it is extremely difficult to produce a
tiniform material from a mix containing coarse aggregate when
ri) walls as thia as those of small pipe.
Two methods of manufacturing cement pipe are employed, known as
tbe **dry'* and the "slush*' methods, respectively. The dr>' method
i» eaM^ti&Uy the same as that of the concrete block industr>'. A mixture
m empioyod which contains only enough water to leave web-like markings
on tbc surface of the concrete when the forms arc removed^ and to bsitl
np ^'h*^ti pressed in the hand. The density of the pipe depends on the
lueas of the ramming of the materials into the molds as well as
■ . ; ... . iLanictcr of the mixing. The dry-mixed pipe also require ciu-cful
curitiit* Aa a result of these requirements* for satisfactory pipe, the dry
net^ ■ " lanufacture gives most satisfaction when conducted in a
piUir ioquate mechanical facilities and storage room. The sludi

ni» thod of manufacture is usually foDowed with the large sizes of pi{)e,
Xlm raateiial is made up into a mixture so wet that with a small amount
(4 mmmhin it will flow into every part of the mold. The pipe must re-
orms longer than in the case of drj^-mixcd pipe, but when
>e pipe require less curing than the dry-mixed product.
h process is advantageously coupled with steam curing by the
lut Vi\H\ Co., which has found that the quality of the product,
' fl V the density of its surface, is much better if the pipe is steamed
itidaft^r it m taken from the molds.

.ur sixes of pipe, such as are carried in stoek for general sale,

^ nodfi on raachinea of two general types. In the first, the space

t shells forming the pipe mold is gradually filled with

-fved by an apparatus which produces approximately the

Imnd tamping. The second tyiie of machine, used mainly

/.<-*, has a revolving head or packer which moves up and

iHuie the tthcU or form for the out-er surface of the pipe, no inner
' ^ ^ of machine*

machines, which are all used with a dry

It the removal of the mold as soon as the machine work

'"'"•*Tly placed on narrow-gage cars having three or four

r<^ run by hand into curing rooms where the pipe

treatments. In a few plants the pipe are

I

352

AMERICA^f SEWERAGE PRACTICE

removed to these rooms on belt conveyors and in the »m.
first cost this part of the manufacturiiig process is carrii

The curing is done either with low-pressure steam or by spfn
over the pii>e from a hose. The atcani is usually employed at
of about 5 lb, and so regulated that the steam chamber will b^
temperature of 70** to 120"" F, With the average dry mix,
are left in this damp atmosphere for 48 hours, although in
weather some makers leave the pipe a day longer, before 8en(
to the yard. It is generally considered desirable for the pip€
the yards at least two weeks before being shipped from the t

The second, or natural, method of curing is generally carr
gprinkhng the pi|>e as it rests on the shelves in the curing iH
water from a hose, This has to be done rather carefully whl
are green^ for it is possible to injure them by allowing a strea
size to strike them directly* The sprinkling is carried on th
times a day fronj the time the pipe are hard enough to stand
rnent until they become well hardened, which may be unywb
to 8 days^ de])ending on atmospheric conditions. The pipe
in this way are usually kept in the storage yards at least
before being shipped. The general opinion seems to be I
curing, when well comhu-ted, not only gives a more unifon
but l» also more economical. A few manufacturers who
sprinkle the pipe sent from the steaming rooms to the yard,
three days after they are in storage.

A large amount of cement pipe, about 400 mfles in ldl2
laid in Brooklyn, N. Y., and most of this was furnished by t
& Baillie Manufacturmg Co., of tiiat borough. Th© methodi
facture were described substantially as follows, by Gii»tave
the company's engineer, in a paper read before the National J
of Cement Users in 1912.

The pit>c are made in 6-, ^, 12-, 15-, 18- and 24-in. sixes, th«
being plain round pipe and the others of equivalent oapftci!
round pipe of the same diameter. They are 3 ft. in length.
Joints, witJi the exception of the 6 in. which is 2 ft. 3 in, '
pipe is round, with a flat base, and the 15-, 18- and 24-in* |>i
shaped, with flat ba^^es. The thickness of the walls ranges
in. for a 6-in, pipe to 2 in. for a 24-in. pipe while the collars I
responding variation, ranging from a drpth of 1-5/16 in. an
joint for a 6-in. collar, to a depth of 1-3/4 in., and a 1
a 24-in, collar.

The cement, sand and trap rock are measureil and thorou]
in a machine, evenly fed to the molds, and rnmmocl m<
iron rammers regulated to produce continuous jmd unj
any impact desiretl.

SEWER PIPE

353

ae oonsi&ta of a mechanical tamper and a revolving table

rbich the molds are placed. The tampers have a vertical reciprocat-

fnotioo and at the t>ame time move outward and inward rapidly so

to eonfomi to the line of the travel of the mold, which, owing to its

form, prcsentii var^^ing diameters at each revolution to the sue-

Bvc tiimping bai^. There are eight tool-atecl tampers, each making

^8(trak63 per minute. Only one is down at a time. The head, which

» of the actuating machinerj' for the tampers, is counter-balanced

as the mold is being iillefl with concrete. The head is raiised

the clcnirity of the concrete and, in thin way, an even and regular

iuct is obtained, Mr. Kaufman said. The force of the blow of

I mmmftr la estimated at 800 lb. The area of the arm of the rammer

Ubout i sq, in.

Tlie prdportions used in recent years are 1-1 /2 parts of Portland

1 part of sand and 3 parts of trap rook screenings containing

I per cent, of stone dust. The quantity of water used to the whole

Wk Vikries from 10 to 15 per cent, according to the condition of the

bdlut. The mix, when dumi>cd on the floor, is apparently dry, but

wD bull in the hand under some pressure. A richer mix is used in form-

^ the eoUar for the reason tliat as the rammers do not exert a direct

l>loi«r fjn the material in the offset, compression of tfie material cannot

t'E dcpeuded upon.

The mixed concrete is delivered to the machines in barrows and is

^l mU) the hoppers by two men, one on either side. As soon as the

Jlaik lA full and the core automatically lifted clear, the flask is taken up

^ i r uck and w^hecled into the stripping rooms where it is allowed

uUy 30 minutes before it is strijiped. After the pipe have set

« rught a spray of water is turned on and the pipe kejit damp for

lUyB, when they are removed from under cover and placed in the

The pipe, at the expiration of 30 days, are set sufficiently to be

led in the work.

8purn for house connections are connected on the pipe. A hole is

it the proper point on the side of the pipe and a mold is placed in

interior. Cement mortar is then spread over the mold and the

•O!u«^ction piece is l>edded in place and a heavy l>and of mortar is wiped

on the outside. After the mortar is removed the inside

lib 1 with a trowel,

yh» method of producmg pipe followed by the Colorado Concrete

Co. was explained to the authors by Edmond C, van

'lo Springs, Colo, as follows:

tnortivr is made of Portland cement^ sand passing 20-mesh and

»anil passing 1/4-in. mi*sh: for larger pipe, gravel pacing 1-

5S-iil. mcnh i« also used. The proportions, by volume, of cement

ht and coars*^ sand arc 4- and G-m., 1 : 0.72: 1,43 parte; 8-in,, 1 : 0.57

354

AMERICAN SEWERAGE FRACTWE

:1.71; 10 and 12-irL, 1:0.57:1.86; 15 and IS^in,, 1:0,43:2.14; 24-ia
1 : 0.43: 2.00, and 0.43 gravel; 30-m., 1: 0.14: 1.71 and 1.29 gravel.

The mortar m mixed by machine, with just enough water to produi
slight streaking on tJie outside surface of the pipe, to facilitate removir
the iron mold. The inside surface remains dry and is polished by tl
rapid continuous revolution of the pif>e around a fixed central coj
The mortar is fed into the machine automatically at a rate to ma^fcco
about 1 in. of pipe vertically per revolution, 4- in, pipe being re vol v ^ed
around the core about 40 times per minute, and 30-in. pipe 6 tiin«3s.
The mortar is tamped with bars as the pipe revolves, two huadc^^rf
70-lb. blows per minute being delivered. One blow overlaps anotfa.cr
by about 1 /4 in, in width, tlie tamping face of the bars being L5 to 2 in-
in length ancl from 1 to 1.5 in. in width, varying with the thickness "'
the shell. The shell thickness is nominally one-twelfth of the diam®'^^
of the pipe, the actual thickness being slightly greater because of '•^^
wear of the core.

The pipe is stripped from the mold as soon as made. The next c^*/
it is stacked vertically iliree pipe high up to 8-in. two pipe high in lO-^*^*
and 12-in, diameters, and singly in larger sizes, and is next cured y
sprinkling with water under cover three times per 24 hours, app^^^^
during the day for six to nine days, depending upon the tempera ti->^*^'
Thereafter the pipe is stacked on its side in a yard and stored for* **
least 30 days before shipping.

The weight of the concrete thus mixed is said to vary from 14^ ^^
149 lb. per cubic foot, the theoretical dry weight of the aggre^i*"^
being 156 lb. per foot. The pipe is without reinforcement except in ^^
bells of the pipes over 6-in. in diameter, which have a ring of rot*****
steel wire from No. 12 to No. 9 B ife S gage in size. This ring has l>^**^
or locked ends of its wire embedded in the angle at the base of the 1'^^
in the plane of the interior shoulder. The bell depth varies from 1 ^ '•
to 2-1 /2 in,; the joint space from 1 /4 to 3/8 in.

Owing to the revolution of the pipe about the core, it is said t.*^ ^
ver>' true to cylindrical form. Two per cent, of breakage is the li*^^
allowed by the company; actually it is generally under 1 per cent ^^'
cording to the company.

Mr, van Diest reports that several thousand feet of this pipe li-*'"
been used under an internal pressure of 15 ib. per square inch or ci'*^*^*
and that similar pipe has been used upon the Pacific slope under p*"**
surcs of 20 lb. and more.

Molding Pipe in Place. — Few attempts have been made to mold «ii*^*^
cement pipe in place, owing to the difficulty of obtaining a good bf^ '
receiving the damp concrete, a( making a uniformly dense mixture uf^*'^
the working conditions at the bottom of a trench, and of protectioK ***

SEWER PIPE

355

injury while green; the low cost of clay and cement pipe have
tended to discourage thU fonn of construction.

work of this class has been done, however, with a traveling mold
y Ernest L. Ransome and used by him in constructing several
\n and drains. It is shown in Fig* 123. There is an inner core, A,
leet ffteel about 10 ft- long in the case of an 8-in. pipe. Ahead of this
nhaper, C, which trims the bottom of the trench to receive the
rrete, and B is the mold for the outside surface. The machine is
^i along by a rope, F, attached to a deadman set ahead and wound
>n the drum, K, by the hand lever D.

I an account of the use of this machine in Despatch, N. Y., H, P.

eftte stated (Eng, and Cont.j March, 1006) that he saw six men and a

fttian lading 8'in. pipe at the average rate of 300 ft. in 10 hours.

tnen were engaged in mixing and delivering mortar, one in packing

to the mold, one in moving it ahead slowly and continuously,

in placing earth around the green pipe. Where a branch was

Led, a hole was cut in the side of the green pipe before the core of the

ho, 123, — llansome traveling mold for ainall t*oncrete pipe.

had been pulled by this place. A branch or slant wa.s then shoved
against the pipe and its collar plastered with cement mortar,
r it the pijie formed by molds of this type from collapsing while

t < >r more of three expedients have been used by Mr. Ransome :

I, usmg a comparatively dry mixture thorouglily compacted ; second,
ig reinforcement; third, throwing earth on the cap mold, JS, and thor-
JJy compacting it there so as to obtain some arching action in the
torn of the Imckftll.

it, Gillette was of the opinion that the speed attained with the mold
lid dej>end very largely on the man who was packing the mortar into

mold, and as this was hard work, it would be advisable to let him
Age places frequently with the man who worked the lever that pulled

Apparatus ahead.

ACTICAL DEDUCTIONS FROM TESTS AND EXPERIENCE

veaiiigations dcMcribed earlier in this chapter show that the load.^
pon pipe are frequently so great that the construction of a tight

356

AMERICAN^ SEWERAGE PRACTICE

8€wer under such conditions calls for good, intelligent work
The experiraents show that the half eloiigatioos of the homou
diameters of cement and clay pipe do not ordinarily exceed 0.02 in. un
breaking loada. It is practically impossible t>o ram earth aroaad I
sides of a pipe so firmly that it will prevent such an insigniiicaotj
ment, and where the pipe is liable to be exposed to dangerousi lo
necessary to use pipe of exceptionally high strength, bed it in a (
concrete, or use some other material for the sewer. It is e^ '
what has been said about the manufacture of clay and cemt.
their tensile strength must be somewhat uncertain and that it i» i
ous to copy methods of construction used in laying cast-iron pipe t
laying the more brittle sewer pipe.

There is a limit beyond which it is unwise to stress any material.
thicker the shell of vitrified pipe, the more difficult it apparently boooB
to burn it uniformly. It will be well, therefore, for the enginw^rl
compare carefully Tables 109, 120 and 121, giving the approximati* ma;
mum loads on pipe^ and the approximate average breaking loadi^ of ]v\
tested by uniformly loading the top fourth and supporting tht^ \x\tU
fourth. These tables must be used with care, for the re^sults gtvtiD 4J
them are averages. If they indicate that a pipe sewer is likely to l>e h
at a dangerous depth the engineer should not expect too much from t
pipe, and he ought to look very carefully after the pipe laying under s
conditions.

Table 120,— Breaking Loads and Percentagbb of AssoRirrioK
low A AND Indiana Vitrified Clay Pipe (Marstox and Andkwsox)

mob«8

Thickr,..^.,

F^rRaking loftfU lb. per lio. ft-

AUnn^

{ Mtijmfiuiu

Average

1 Minimum

ptnm^

6

0.62-0 75

2,690

1,960

1,690

I M.6;

8

0.70-0. 80

3,320

1,040

1,400

3 54 I

9 '

0.70-0,80

1,970

1,710

1,430

1 2-1.7

10

0,80-0 88

2,840

1,850

1,210

3 (M.»

12 1

0.85-1.10

3,400

2,120

1,370

1 7-4«

15 »

1.00-1.30

3,890»

2,120

1,220

l,M.fi

w 1

1.20-1,50

4,370*

2,770

1,570

l.^J

20»

1.3-1.8

4,920*

2,910

1,720

8.W.8

21

1,5-2.0

6,600'

4,620

3,030

4 W.3

22

1.7-1.7

6,060«

5,010

i,sm

3 1-41

24 »

1.3-2,1

5,620*

3,360

2.or,o

1 «M «

27"

2,0-2 4

5,940=

4,260

3,0H0

3Mi

30*

2 2-^2.7

6,930»

5,050

8,00

H M-»

33'

2, ,5-^,0

6.310

4,620

zMo

3 ;m»

36^

2.5-3 0

6,340'

4,980

3,000

4.^^

t Some of th4* aJDgle-etreiMCth pipe der«loped greater rMitUoeo Ut br<«l(iiu liuft *
the doubJeN^treiuBih pipe.
* Doubli^4tnsii2th pipe.

SEWER PIPE

357

At thifl time (1913) there is much controversy over abaorption tests of
clay ami cement pipe. Marston and Anderson have reached the con-
clusion that the maximum permissible absorption by vitrified clay sewer
pitna IS 4 to 5 per cent., because more absorptive pipe is always un-
flKtisfactory from the viewpoint of strength. The data for cement sewer
pipe m their poa!»ess«ion are inadequate to warrant any definite conclusioa
regarding huch material. See Tablcii 120 and 121.

1^-*BLi 121. — Tests of Breaking Load and jVbsokption or Iowa Cement
Tile (Marhtox and Andeh&qn)

Mix

Thick noaf,
iDohel

BrenkifiK load, lb.

MAii-

mum

Avomge

per Im. H.
mum

i
5
5
7
8

to

12
11
16

m

22
U
26
2S

30
32
34
36

1:4^1:5

1:^-1:5

l:3i-l:4

1:4-1:5

1:3-1:4

1:3-1:4

1:3-1:5

1:3-1:4

1:4

1:3-1:4

1:3-1:4

1:3-1:4

1:3-1:4

1:3

1:3

1:3

1:3
1:3-1:4

0.35-0,70

0,45-0.75
0.45-0 SO
0 5W)-80
0 Or>-X,35'
0,70-1.45'

0 75-2 25

1 0.5-1.55
1.20-1.70
1 55-2,80
1 60-2.20

1 90-2 45
1,70-2.50

2 10-2 70
2.00-2 80

2. 60-2. SO

2 80^3,00
2 80-3 SO

IJIO

1,130

2,260

1,460

2,060

1,190

2,070

1,290

2,330

1,370

2,030

1,230

5,700

1,510

2,510

1,380

1,420

1,200

3,800

1,450

3,720

1,890

2,280

1,840

2,240

1,720

1,960

1,740

2,240

1,730

1,680

1,570

2,700

2410

2,070

1J60

3,230

2.670

890

550
540
740
840

510

460

680

1,000

6(X)

l.llO

1,480

600

1,360

1,4^40

1,460

1,600

1,460

1,980

Absorption
percenttt^e

5,9

6 8-11,3

3 9-11.6

8,8

8.9-11.3

7.0- 9.5

6.2-13,6

4,4-13-8

5.3- 9 6
4.9- 9 6
5-7- 6 6
5.3- 8 0
5 4- 8 2
5 5- S 4
5,9- 6 0

6,2- 7 7
7 0- 9 2

*Tbc iiinMliatiy Uiiek fh mul 10-m. tile were from dO-ycnr old draina taken up In Ames,

The development of the cradle of concrete uned at Washington to
^*rr>' the pipe sewers is shown in Fig. 124. The 1871-79 section had a
^urUf jttini and terra-cotta band and the pi^ie were without hubs,
'rue of all pipe used down to the present time. When
itig H. Beach was in charge of the sewerage work there
*^ nj|iorted that "the bottom of the sewer, with this pijie, can be made
^^:^^ even and free from projections due to irregularities of

\^^' e'* than with bell pipe. The first section was probably

'*arK prior to 1871, according to information furtiished by
,^Sj BUpcrintenrlcnt of the sewer department of tlie District
i., but tlmt date is the beginning of the publi(^-pcmritte<i
I H of thiu typo for sanitary drainage. From 1879 to 1888

i^k

iH

358

AMERICAN SEWERAGE PRACTICE

^^'ililr^N.

::L5>:^v.

1871 -ie79.

ia79-ie88.

1888-16^.

1894-1903. 1903-1914.

Fig. 124. — Cradle and joint of Washington pipe sewers.

\

''''^

■ *'• ■* " ■

Chn'C'^

Concrete

I Boarat

BroHK. Medford.

Fig. 125. — Types of cradles.

SEWER PIPE

359

jpipe rcHted In a crad!e of uatural cement concrete 22 in. wide on

|b«ttom and 6 in. thick under the pij>e, while the joint was made with

3-cotta Imnd and a ring of mortar 4 in, thick, 14 in. wide at the

i hm\ ti in. wide on top. The 1.S8.S-1894 cradle was wtdcncd to 24

ut otherwise it and the joint were unchanged. The lS04-190:i

lie remained unchanged but the terra-cot t a band v^aa left out of

I joint. The 190^14 cradle was made of Portland cement concrete

I iu dimen>?iuni> were reduced a little^ and the joint was given aEJ

"eiy new cross-s*ection. The concrete enve!o]>e was first adopted!

' 1S79, according to Mr. Phillips, as a preventive of root intrusion, by

t. Hoxic, while engineer commiesioner of the District.
. 125 8how.s three different typoa of concrete cradles used with bell
pigot pipe.

REINFORCED CONCRETE PIPE

Lock-joint Pipe.— In conetructing reinforced concrete sewers in a
rt?nch, ihe practical difficulties lie mainly in making desirable progresfl,j
* haiuLhng and setting forms, in producing a uniformly denize, bard
*lictt!le and in keeping the reinforcement in its proper place while
Ifceoncrete is deposited about it. The lock-joint pipe wa« developedg
^PCofrman Meriwether to overcome the^e difficulties. It consista"
^ reinforced concrete shell, either circular or egg-shaped, made in 4-ft.
*; this length has been found economical to handle and materially
the niunber of jointi* per mile of sewer a^ compared with the
needed were shorter lengths used. The pii>e can be cast with
lings to receive standard vitrified cla3' or cement pijie or slants,

T'n or Y's are needed. The usual reinforcement is Triangle^

b, made by the American Steel & Wire Co., but other materials^

' be employed. On the larger pii>e the shell is reinforced near both

Kitrr and inner surfaces^ but in the smaller size^s the inner rein-

^ment is all that is generally used, usually at a uniform distance

I the inside of the pipe* Where the pipe is required to have a flat

1 instead of a perfectly circular section, the ring of reinforcement is

' the inner surface at the top and bottom and near the outer .surface

ch «dc. TluK theoretically desirable position of the reinforre-

is practicable where a flat base makes it certain the pipe will

^yK bo laid bottom down, but with plain pipe of large size there is

tmoertainty about this position being maintained with every

lie lock joint, Fig. 120, Is doultly reinforced. The reinforcement of

rtcU prfijccte somewhat at eacli end, so that when the pipe are placed

wition the two sets of reinforcement overlap* After a length lia^a

1 located in iU Hual place in the tnmch, a metal shield is temporarily

AMERICAN SEWERAGE PR.

placed inside the pipe, clasing the joint, and the latter is fill*
grout made with cement ground unusually tine. This is usually poi
through an opening left in the lip or bell of the shell for this p
but sometimes the joints of sewers undex 3 ft, in diameter are filled b
means of a grout gun^ a device for forcing grout into cavities by subjeclB
ing it to pressure. The joint made in this way has been repeatedly
tested by internal pressure antl found to be water light under all head J
to which the sewers were subjected. Circular beams of three lengths
pipe have been made up without special pains in jointing; these havi

Outside of Pipe

k-„..

-S"— *W^g.-j4

Qroottct Jotnt

Fig. 126, — ^Tho joint of Lock-joint pipe*

been supported ne^r the ends and heavily loaded at the center without
causing fracture, showing good locking action of the reinforcement ir .
the joints.

Table 122. — Stanwahd Dimej^sions op Lock-joint Pipe, Lenoth 4 F'T'
TftiANOLK Reinforcement. (References are to Fio. 126)

&

/,

z.

it.

in.

in.

ia.

in.

II

2

11

2

11

2

11

2

3i

a

3|

3

3i

3

3i

3

3i

3

3t

3

31

3

6

3i

3

a

3J

3

6

31

3

6

31

3

6

31

3

6

Reinfofot*-

ment* lb. per

wi, ft.

No. ot
tftyers
of Mttfel

Wcifht.
Ih. p*r ft

0.30
0.30
0.40
0.50
0.60
0.60
0.60
0.73
0. 73-0. 83
1. 00

1 n<vi.2n

IJJO-I
l.OO-l
i 20-1
1.60-1
I KO-2

Single

Single

Single

Single

Single

Single

Single

Single

Single

Douhlfs

Double

Double

Double

Double

Double

Double

250

350

380

480

520

530

(y70

730

S70

1070

1300

1370

1540

1800

2250

2^100

J^tfiBt.— Tbc reinforernttJtii in tb« minimutu usimI under ordiiiiiry nirt>utntttAA«««^ lA
l^rsit Bc^wer with very Ittllv buckfiU over it and uot likely t0 bo •) ' » ||es<

niovinif ItJuda, « BjimUcr ocmouot ui «itf«I ItiAa Ihjii NL%t«ri would 1 b)^

Loek-joint Pipe Cr> -k"*- -v^' ■»— ^ .,...;.k.. ... ,...,,,.. ^,*-.. ►.-,,, ^„ , , ^.^i^j^i

rmpioyid •

SEWER PIPE

361

The mamifricture of the pipe is marked by several novel methuds

devwl(>rK»cl since the first sewer of this type was laid, which was in

Wiimiogton, Del,, in lUOS. The concrete is mixed in a small mixer,

in whirh the water is drat placed, then the cement, then the sand

*ntJ finally the 1-in, gravel or broken stone. Experience has con-

I viDced the Lork-joint Pipe Co., which controls the Meriwether system,

[tluit this results in better mixing for pipe manufacture than the

sual procedure with a large mixer. Only a rich mixture, at least

1 1:2:4, is used, for the company's experience indicates that denser,

sUonger concrete can be obtained from wet, rich mixtures than from

mixtures contaim'ng water-proofing compounds but made less

fully. The concrete is usually dumped into a metal pan, where

Ha quality can be readily seen, before it is taken to the molds. If it

_to poor, the panful is thrown away; but this is rarely necessary when

ieoeed men are employed. The proportions of the mix are fixed

^ plac^ across the box of the wheelbarrow used in charging

r; thin method makes it impracticalile to alter the propor-

^ except by placing the ingredients in the wrong compartments of

iwheclbarrow, which would be quickly detected by the mixer operator.

The mokls in which the pipe are made are not sold and are leased only

which are putting in sewers by day labor. Where contractors

luse the pipe, the company manufactures it for them on the spot,

>r which purpose it maintains lis own gangs of experienced men. The

"v will not allow contractors to make the pipe because of the

uty as to what kind of work would be done on a Umng contract.

Ii4t w»t mixture is carefully tamped around the reinforcement^ which is

^t-^^ld firmly in place within the molds. When a mold has been filled,

r pipe 18 steamed foreeveral hours, then the mold is removed, the pipe

I with canvas and steam is again turned on the pipe for several

^Jn this way the outside and inside of the pipe are given a finish

vmooth aft that of hard plaster, except for the presence of occasional

ptt{«.
The concrete thus made la bo dense that the company does not advise
vert of the sewer with vitrified clay blocks, although it has
h inverts lined with special tile I in. thick and 2 in. wide,
riocked with the concrete. The preference for the concrete over the
Rti%*tTt tit based on examinations of the condition of lock*jojnt sewern
►*i tteep icrade^ after several years of ser^dce and on experiments made
Engineer of Sewers and drainage of Newark. N. J.,
Imp.f 10Q9) which indicated that it w^as unneces-
" to iioe dfiAAB, hard concrete with paving brick or vitrified tile.
KV' '- '* '""Tiufacturc of reinforced concrete pipe as compared with
of a reinforced concrete sewer in forms in a trench
cWititsii U> be much easier work and of permitting more thorough

362

AMERICAN SEWERAGE FBACTICS

i&iipectioii, molded pipe has otlier advantaen wUdi are saki to ]
prcTVod helpful In practice* The first is the pfacticabBity of nuilcitig
pific hy the method junt described in the m<wt severe wuit<n, aifb-
moriitiraiixl in CunudiL and the United States. Another advantage a
the narrower treoch which can be tued with a cast pii>e, as was ihowa
convincingly in the narrow stroeta of Havana, Cuba« A third advaatais
is the very short trench which need be opened, because as soon as tk
bottom irt reached and prepared, the pipe can be laid and . ! :

nothinjc to interfere with backfilling. With sewers po»j
the trfiiich, a much longer period must elapse before backfillnig. Inw*
nuK'h oM the joints in the larger siics of some pipe can l>e made from
i\w iiiHidfi, if neccssar>% it has a special advantage where seiilement a
f pared during back filling, for the joints need not be poured until after th«
fill iH in place.

in IDlii the company conducted a series of experiments to deli*rmm«
Ihu poHBibilily of laying pipe with lock joints to withstand inW'niftl
pn^KHurrH up to about 75 IIk i>er 84uareinch. The results wt^reio^'^uc-
ccHHful that thn company decided to take contracts for such prc*«tif<!
ctjtuluitH, the lirKt do«ed being a pressure line for the Baltimore watf/
workM,

Jtckflon Pipe.^In th(^ typo of pipe made by the Reinforced Con '
Pipe ikh, of Jat^kHon, Mich-, from five to seven longitudinal reiti(ii! ! -
bar« are usually employed and two or three hoops. The wall thifktif^'
rnngoH from 4 in» for 36-in, pi[>e to 7 in. for the 72'in. size; the ujinil
It^u^^th is 3 ft, for the medium sizes and 5 ft. for the larger* In ^^
standard tyiw, one end of each pipe is recessed on the inside and the
end hitH a bevel or taper and a rebate; when a pair of pipe are put tog<
the inner surface is unbroken at the joint and the outer surfa<-e hfl*<
groove. The longitudinal reinforcing bars project into this groove.
Dmr ends aro Inuit over to form hooks; a band is threaded ihiou^
these hooi>s and thus interlocks the longitudinal reinf orceins ut
successive lengths c»f pipe. When the reinforcement has been couples
in this way I a strip of canvas is placed around the outside of the piiieai"^
held in fmsition by a steel strip. This cloi^ies the gnwve exrejit f«r «
opouing about IS in, long at the top of the pii>e, through which thin K^"]
is pouhmL As soon iva the joint has been filled, it is desirable to tn^V
the imcrior of the pipe and be sure that there is no indicate >>> **f *'"^ '
deft>cts, which sometimes are detected in this way*

T\\c actual n tro of a 72-in ' ^L Ji>-P!j

XIo., was dt^Ci I '1^. Record, A I

** la tho pitMns of maniifaHunng the ptpii, a I ^ torn platt of €^ '
b u^riK jiha|ied 90 aii ^ n^ flanf^fd

The ei>re dafiniiiK th iiamelar

atetioQs of tolM shtovt «i<id on thfc Qpi

Ar^

SEWER PIPE

363

agttudinal reinforcing bars are inaerted in receiving sockeU In
the outer ease is then added on the lower and outer flange,
ig bars are held in place at the top by space clips. The cir-
aforciiig bands are slot-punched^ so as to receive and aceonimo-
l^^ttudiiial bars when the hands are put in place, as the process
^Bi followed. The concrete is shovel etl into this form in very
emtities and the tamping is continuous, with the result that there

Eor creases in the finished pipe. The concrete used in this
iposed of 1 part American Portland cement, 2 parts river
>arU crushed limestone; the latter being a niixture of two
g from peanaize to 1 in* in cUameter, The resulting concrete
ally dense,*'

Jy the conditions are such that it is desirable to make the
Cribed on only the upper half of the pipe, as it is placed in the
Ijoint for tlie lower half is made by havinp; the groove on the
^pipe, instead of the outside. This enables the pouring of the
lower half of the pipe to be done from the inside, which gives

ag conditions under some circumstances,

ftcuse, N. Y., intercepting sewers about 11,500 ft. of Jackson
itn used up to the close of 1913. This was from 33 to 60 in.
^Ujr and was made near or at the side of the trench by the
Concrete Pipe Co.^ as is the Uasual custom where this system is
, The work was done under Glenn D. Holmes, Chief Eng.

cuae Intercepting Sewer Board, whose requirements for
nt somewhat exceeded the company*8 usual practice. They
, Table 123.

-RjCIKFOBCEMBNT IN JaCKSON CONCRETE PiPE SeWERS IN

(Glenn D. Holmes, Chief En am eeh)

k; . ^ ~^

Clrculnr

Trittngle

Sheets of

TbickoeM of

^^mt%, iacbe*

bunds, inchea

mesb. ttumtwT

nietml

pipe, tocbea

■ IX)

ixi

3

Single

31

■ ix}

ixi

1

Single

41

T i^l

ixi

1

iSingle

6

1 ixl

ixj

10

Double

51

ey Pipe. — The reinforeed-concrete pipe made by the Parmley
»rcut Co,, of New York and Chicago, ia cast vertically in molds
»n l>ottoms and atoel sides, carried on platform cars which are
Btng ahakea vertically by a * ' j ol ter ' ' or cam device. The cam
a hundred 1-in. vertical jolts a minute, which the makers
I groat help in producing a dense concrete. A plant used in
f pipt* in this way ia shown in Fig. 127. The pipe are usually
^t. lengths but S-ft- lengths are also made; the largt>st size
913) ia 72-in., although tl»e company has made its designs for
9 Ktaied in Table 124. The pipe are largely used for

364

AMERICAN SEWERAGE PRACTICE

"Flo. 127. — Plant used in making Parmley pipe.

culverts by railroad companies* For pressure pipo their most imp
tant me him been in 6 miles of 36- and 4S-in, aqufdurt, tmdcrj
maximum head of about GO ft., for the water-worka of Fort Worth.

Taiile

! 124. — Dimensions

of Standard pAtiMUEY Pipk,

Width of
bmao. ia.

ThidtJ
crown.
ia.

Q««» at
base,
iu.

Trunavcrse
•tceh aq* iu.
per Im. fi.

»tppl. lb,
perUiua.

1

24

8.5

2i

2i

0 10

4,17

IP

27

9,3

21

21

(Lii

4.98

27*

30

lOJ

21

31

0.13

1 1 ■ '

33

U.O

3

4

0.15

"

3e

11.9

3

4

0 10

39

12.7

3i

4

0,18

,,i ,

42

13,5

3i

4

0 18

11.21'

45

14.2

31

4

0 21

13 3 J

48

15.1

4

4

0.21

14.i:>

51

16,0

4i

41

0.23

16,31

54

17,0

41

4i

0.24

17 3:.

57

17.8

M

41

0.24

00

18,9

5

5

0.24

66

20.6

5i

H

0.2»

2a. 76

lU

72

22.5

5i

5J

0.34

90 &9

uw

78

24.2

51

H

0.30

$4.60

ITU

84

25 9

6

6

0 40

41 53

\MT

SSWER PIPE

366

The pijje are made with boll and apigot ends for culvert and like uses
with Uie bub and spigot, so formed as to leave an interior annular
ivity into which grout can btj pourod through an opening in the top.
The pipr are made either circular in croiis-section or circular with a flat
There are two aystema of reinforcement, a sheet of triangle
near the inner surface and a series of hoops curvxd to be near the
mirfaee at the top and bottom of the pipe and near the outer
eutf ace at the ends of the horizonta) diameter. The concrete is usually
1:2:4 mix, with the stone or gravel between 1/4 and 3/4 in, in
3; the grout U9ed in the joints is a 1:2 mixture.

STEEL PIPE Airo FLUME

Riveted steel sewers are used quite extensively in Jersey City, N. J.,

flmre they have found favor on account of their flexibility and low cost

pmpared with other typc^s of coostruction suitable for craving soft

low land and operating at times under a considerable head. These

ircrs are generally employed as outfalls on low land and receive sewage

^Qia trunk lines descending rather steep grades from the more elevated

listricts on wliich the miiin portion of the city lies. For example, a

J2-in. aower about a mile long, which receives the sewage and stonn water

a thickly settled area of about 60O acres, had to be designed to

l^perate under a maximum head of about 05 ft* (Eng, Record, July,

11K)7).

Pipe Details.^Tho pipe was made of 1/2-in. plates 6 ft, 3 in. wide,

nade up in lenj^hs of three courses, or 18 ft,, in the shop. The seams

t 3 in, wide with a single row of 7/8-in, rivets driven on 4-in. centers.

fidway between the successive circular seams a 4 X 4-1/2 X 1/2-in.

ngle was riveted as a stiiTenerj using 7/8-in. rivets on 6- in. centers,

■The pipe waa coated with rehned ufiphaltum. Manholes were placetl

|evfrry 500 ft. and automatic air valves at similar intervals and every 100

an expansion joint, Fig, 128, was provided.

The sewer was supported under railroad tracks and on soft marshes

on thrf'opile bents 8 ft. on centers. The piles of each bent were 4-1/2

ft. apart and were capped with 12 X 12-in. stringers on which a close

poor of 6 X 12-in. timliers was laid. On this floor was placed a bed of

^Ucrete wliich was carried up on each side to the elevation of the center

the pij>e. Under the tracks, the angle iron stiileners were omitted

^cl the pipe was entirely covered with concrete, as shown in Fig, 129.

iTie design of these pipes comprises the determination of the probable

Bting pressure by the method explained in this chapter under In-

lal Pressure upon Pipes, the selection of steel thicknesses and rivets

*l? to meet these pressures in the usual way, and the adoption of meas-

^ftt to prrv^ent the distortion of the pipe by rough handling, exterior

366

AMERICAN SEWERAGE PRACTICE

pressures, ai)d a partial vutnjum should the pipe be drained wbiiMJ
upper end waa closed. The distortion of riveted pipe is a danger br
DO means remote, and should always receive careful attention.

The steel used in riveteti water pipe made under the si>ecificatioM</
engineers who have devot^?d mtich study to the subject ia umt^jfi
the quality demaiHled by the flange platt^ specifications of the Ar-^-^^
Society for Testing Materials, The desire to have special u:
in stren^h and good resistance to corrosion is responsible for tin
ment that a certain percentage of the top of each ingot from w,
plates are rolled* such as 20 }>er cent* in the case of Alien Haven's »^
fications for the Little River water supply of Springfield, Masa.^ abU hf
discarded.

Riveting practice in Huch pipe w*ork is indicated by Haven's requrT^
menta for the Little Ri%^er supply, just mentioned; these are givmj
Table 125, These specifications permitted punching the rivet I

^h'¥ets,4''CfoC,

Fio. 128. — Expansion joint on steel
BPwcr.

- — — //i

ppf^

Fig, 129. — Oowiiifsi
railrond tnda.

full size^ but some engineeia require the puiich to be under-siju? and ^
hole to be fim'ahed by reaming. If the holea are punched full *i«» ^
punch should be applied to the side of the plate which will l>e in cmtMA
at the joint and all burrs should be removed. Where tran«vi»nie oiw
longitudinal seams meet, the edges of the pliites should !
down* and, if possible* two of the nveta of the circular »e^
driven through this part of the joint. The riveting requirement* irtt
as a rule* those of good boiler practice under rigid inapeotion.

The anchorages for holding the Little River pipe at tliegat<!i**
the various summits consisted of double blocks of concrete
ft. long and 13 ft deep or 13 X 11 ft., about IS ft. apart and tir .
steel by means of a number of 3-1/2 X 3-1/2-in* angles riveted
the pipe like hoops.

SEWER PIPE

367

r atcel pipe paaa under railway embankments they are either
irj concrote or strengthened with hoops and longitudinal stifFenera
' Miglc iron

ft

i

ft

f

I

}

H

u

H

li

1}

li

I 9

2 2

2.1

3.1

3,5

3.2

n

11

u

2i

2i

3

4

4}

4i

Table 125.— RnijTiNO DiMSKSfOKs for Steel Pipe (Hazen)

iTliit^itiicw of plAt«, in J

t>iafliet<r of rivets, in |

^I>i«mctcr of rivet-holes, in . ^

f2»^olcr of rivet to edge of plate, in. . , 1 1

Vpproximate pitch in all single-riveted seams, in. . . 1 . 67
approximate pit^h in double-riveted seama, stag-

pamd, in. ,...._._ _ 2,66

ftttPO between rows, double riveting, staggered,

ik,... li

iof platirs, single riveting, in 2i

tp uf plateSf double rivetiogi staggered, in, . . . , . 3|

Ko(c. — These requirements were for 42-in, pipe made in 30-ft. lengthfl
knb fourth length being required to pass a shop hydraulic teat of 100 lb,
>r l/4-in, thickness plate, 150 lb. for 5/16 and 3/8 in. thickness, and 200

for 7/15 in.

Ix>ek-l>iir steel pipe, in which the longitudinal joint is made by holding
» two edges of the sheet together by gripping them in slots in a long bar,
[ by riveting, has bec^n employed for the new 66-in. outfaU of the
r, X. Y.> sewerage system. These pipe are made in this country
"Onfy by the Kast Jersey Pipe Co., of New York, and their ude has been
^naioly for water mains.

B A grave danger always exists with large steel pipe which may be aud-

W1«l1 • 1. for they are likely to collapse then, flattening out on the

^^FtKii ha way as to ruin many of the sheets of which they are

compo0od* This has happened enough times to make it imperative for the

f *ngin«?r in charge of pipe systems containing such steel riiairus to post

^arniniCB against any manipulation of valves or other operations which

r. Furthermore ever>'one about the system should

< rning this peculiar danger, in order that any threaten-

^i condition will be reported at once to headquarters.

Pipe Coating.^The protection of steel pipe against corrosion has

j fooeiv^^d much attention owing to the pitting of important water mains at

Roclk»ter, N* Y., Atlantic City, N. J., and a few other places where

unoiiial CMe was taken when the pipe were first laid to liave them well

' pralictcd. The defmite infonnation on tlie subject m now (1913) so

ii*nrH should keep careful records of the condition of the

^ of all riveted pipe just l»efore the backfilling is begun

^l at pieut occasions when the lines are uncovered. This

^ii^^^rnu^r ( ftlno include a careful statement of the nature of the

S68

AMERICAN SEWERAGE PRACTICE

material surrounding the pipe. It is only in this way 1
aen^ice records can be obtained.*

The protective coating adoptetl by Hazen after long investigation for
the Little River works of Springfield, Mass., was made at first from cocJ-
tar pitch distilled until the naphtha was removed, and enough r*w
linseed oih free from acid, to make a smooth coat, tough and t^nacioiM
when cohl and neither brittle nor scaling. Straight-run coal-t4ir pitch wis
used; it softened at 60" F. and melted at lOO*' F*, and was a grade in '• ''"^
distillate oils^ distilled from it, had a specific gravity of 1,05, Tli*
was required to have at least 10 per cent, free carbon, and as muc
as was needed to produce the desired qualities in the coating, r
quently dead oil was substituted for the Hnseed oil. The material wi*
heated to 350'' F. in a tank and the pipe were dipped vertically io it
after being brought to the same temperature. Tliia coating ia troulilt^
some to apply, and the asphalt pipe dips, which are successfully tiW
between wider temperature limits, are more often employed. Grnphit|
paints have been used to a considerable extent oo riveted stod
mains, particularly where they are not buried.

According to tustinmny by representatives of the American A5j^h*i^
& Rubber Ca in the Byerly ^M^lown-oil" litigation, the **Pi"
pipe dip was composed of about 28 per cent, gilsonite and 72 pi-r - :

1 That the pretemition of pipes by protective coatings reecivf^d the e&mevt «tt«iiitl«t ^
cngiae<>» many years ago may b« oiisily learned by anyone who will t<"i '
18&8 by Jumefl P. Kirk wood to the Brooklyn Wat«r CommtMioti in r • '
made by variou* parties to protect cast-iron pipes from corrn-f - ^ • '
of which a copy is in the library of the American Society of t
rofluJtB of advertiaemvnta in lending journiib of the United 8t i
for coating the Brooklyn pipea to prevent rusting and lubprrul^itiop. K
from Eniiland, Scotland, France, Germany and Austria, and some of %Xu
edce of the effect of difTenrnt classes of wat<-«r8 on different daflvrs of ],i. m1
whtoh antiripatcs tbe discoveries of a later generation. In fact, in 183^J -Til l HOl
Mollet publtfihed in the proceedinga of the British AAaociatiou inonoieraph^ nii thr {zi
of rttating which it would be welt for the enthusiastic cooirnen tutor on ntodlrni
research to read carefully.

The ooAting deviaod by Dr. Angua Smith and now uaed iti % modiEed toma tm
waa deacribcMd by him in 1850 as follows:

"The pipe is made clean, free from rust, and earth which cling* to it
molds. The cleaning is a very important thing, aa the fiucc««c y/vfy otn'
The surface is then oiled with linseed oil in order to preserve it until it in rf»uJi> tobsj
when tbe coating is to be made, the pipe is hentod in an oveu to about ^Kf t>*, tt
be makQagcd in aueh a manner as to prevent 8ch>t frrmi settling oc U. It ]
a pan of gas pitch and kept in it for aomo time until it hits tukm up tin
aa poaatble. The pit<!h should not be too hard. »o ^ -' i — * ^— i^-..u
aoft, ao aa to adhere to anything. When it hec<".
more oil; when the pipe« are taken out they are r
exceedingly well.

*' An oven is made to heat tbt» pipaa lDi and from it they ate tranaff^rred tn the
they are dipped vertically, slowly removed, the ti<iuid running off *
tldn coating. ... I do not know if ynu Imve any distiUcrir>N of (
you will readily obtain the proper pitch; we like ft dinilled till tl
latency of wax in our climate If hard, the mixture of 5 of «i pm
advantage, or even if uot very bard/' Letter from Dr, 8m«t^ ' ' ,,,,»^^

SEWER PIPE

369

P^rtrfjhnim residuum, and was prepared by blowing air through the melted
tnmteriftls for 35 to 37 houm. It was one of the so-oalled mineral
itiUxiini with a high melting point and rather unsu;scoptible to tempera-
ture changes* C* N* Forrest, clnef chemist of the New York Testing
I-aboriitory, statues that this material will not withstand sunlight and
atmospheric conditioiia for much more than a year; this confirms the
[ *?xp«riencc of engineeris who have had pipes coated with these dips exposed
fiur s&vf»ral months along the line of the ditch. Mr. Forrest believes
llut if the pipe are free from loase scale and are clean it is unneceasary
f liejn t)ofore dipping. Both he and Dr, Clifford Richardson are
upon keeping the bath at the proper temperature and the
Jroper eotiaiflteney.
Experience with coatings of \\T0ught iron and sivtA pipe in California
ad some neighboring states has been qyite diiferent from that in
stateis. The extent to Which this is due to difTerenccs in soil
I water, on the one hand, and to the character of the coating, upon
i« othrr, httfi not been determined* It is probably true, however, that
don, pitting and tuberculation of the pipe and blistering of the
ngm much less rapid llian under conditions in the p]astern Ijiited
icept in certain i>lack adobe or highly organic or acid soils
lips in some unusjually porous soils mth very slight covering
rthc pipe.

he most important lesson to be drawn from these Western ex-
fTJcnces secmi? to be the marked effect of the use of coal tar in pipe
riatingj* in tending to preserve the elasticity of the coating, as indi-
it<^ by the experience of Hermann Schussler, who enjoj-s the unique
fiction of having guided the engineering development and dej^tiniei
] of the hirgest public service corporations upon the western sloi>e,
Spring Valley Water Co., which supplies the City of San Francisco
ith water, for a period of substantially fifty consecutive years, and of
mng built during this time many miles of wTought iron and steel
ipc lines for it and for other water and mining corporations in this
icinily. His experj*mce ha^s therefore covered a sufficiently long period
time to be of significance under the conditions there prevailing.
While the early records of his pipe coating methods are not as pre*
ght be def?ired, the following description, which has been pre-
conftTence with him and wnth employees of The Spring
fwS\ Go. and is published by courtesy of its officers, is probably

^Xlli^ _.....,:.. m accord with the facts.

The i]]at«*rial U8<»d m the coating is composed of a high grade of
}aaphaltum, mined at Santa Barbara, and a high grade of domestic
i tar. In the process of rehniiig used, one batch croutaining about
I ^gtti, of coal tar is poured into a refining kettle under wliich a fire has
N<vi. .t .r^t.^J ^ter which 900 lb. of crude osphaltum, previously broken

370

AMERICAN SEWERAGE PRACTWE

Into chunks from 2 to 4 in « in diameter^ is added. As this meita, motg^
aAphhitum is added, and the mixture stirred, until a total of abuut 3,^
lb. i& placed in the kettle. A second barrel of coal tar b then add
little by little, to prevent boiling over, aa this mixture has Ijeen fou
to give a ver>^ tough and tenacious coating on the pipe. This pr
requires about 8 hours, the boiling taking place; at a temperature probailj
of 300" F. The material is then allowed to l*oil for about 4 houre witb^
stirring, when the floating dross is skimmed off and the refined
phaltum baiie<l into a dipping trough, after w^iieh the heavy m-faw*
which has settled in tfie iKjttom of the kettle is removed and a nrw
charge is put into the kettle. This refuse, consisting largely of i
and gravel, was found upon two recent occasions to average 655 tb. i
weight per kettle.

Hy a slow fire at each end of the dipping trough, the bath id \
nally raised to a temperature prol)ably between 360^ and 400"
or if two different troughs are used for the successive immersions tif t
pipe^ the second trough is maintained at a temperatue about 30* I
than that of the first, the bath in each ease being of sufficient depth i
cover the pipe. The consistency of the dip is maintained by the i
ditioii of rctined asphaltum from the refining kettlr and of <'oal tax, \k
projK^r consistency of the coating being tested from time to tunc I
dipping a stick of wood into the bath and, after the coating \xm cooh
noting its resistance to the point of a knife. In a long run
and iiiptvdipping, the proportions of the constituent mat»-f
coating were found to be approximately one 5G-gal. barrel oi ood (
U) 1400 lb. of crude asphaltum.

The cold pipe is immersed in the bath for a period of time sufBcin
to bring it to the temperature of the dip, which is detrr
ing a bar along the innnersed pipe. If the pipe has an
perature of the bath, the bar will slide freely upon the metal surfAWH
the pipe; if it has not, it ^411 drag* Pipe 54 in. in diameter. O^Si
thick^ was found to require immersion for about 25 minute.
temperature of the bath is maintained by the fires. Before fPiUff
from the dipping trough, the bath is vigorously stirred and the pipf >
rolled in order to secure a miifomi quality of coating. The pipe it Ik
raised above the trough, suspended at an angle of 45** to drain i
while the bath is vigorously stirred again. When thf fonfm^l
suspended pipe ha^ cooled to a firm and very sticky -
pipe is again immersed in the bath or in the second dii^; :,..
such be used, quickly rolled, and after 3 to 5 minuter again mnot^
suspended at an angle of 45** to drain and cool, and is then lowfrtd ^
skids coated with dry sand, and removed*

The records are not sufficiently extensive to determine with ftc
the thickness and increase in weight due to the coating. T^^'^

mm

SEWER PIPE

371

S68 of coating is probably about 0.05 in. (or from 0.03 to 0.07 in,),
and the inerease in weight probably about 0.38 lb. per square foot of
surface (noated upon one side only), varj'ing from 10 to 12 per cent,
for the lliin pipe to about 7 per cent, for 1 /4 in. pipe coated upon both
Rciea.

Hundredd of feet of wrought iron pipe coated under Mr. Sehussler's

Idtrection, of various diameters up to 54 in. which had been in active

Iwater-Cftrrying service in the vicinity of San PVancisco for various periods

lof time up to perhaj)® 47 years, were examined^ both inside and out, by

I the authors. In most case^ the coatiupj upon the interior of the pipe

Iwa^ smooth and unbroken, still adhered tenaciously to the pipe, and

I could be dented readily by the finger-nail and pushed aside by slow

[hard pressure without cracking, the pipe being clean undernt^ath, show-

ag the mil] scale in some cases. Very little corrosion, tu here uktt ion

[)r pitting of the pipe or blistering of its coating was found, the carrying

capacity being remarkably well maintained^ probably within 10 per

ent. of its original amount in most of the pipe, and within 20 [>er cent.

in the oldest and worst case found, m indicated by certain friction loss

s. The exterior coating^ while on the whole not in quite such good

Icondition aa the interior, was found still generally sound except in those

t few ernes of very limited length in which the pipe traverses soils highly

organic or acid in content, such as certain black adobe soils and salt

water mar**hes. The record is a very creditable one.

Further comment on the coatings iLsed on .steel pipe on the Pacific
Coast is given in the following extract from the final rejKJrt on the Los
Angeles aqueduct:

**A large variety of paints and protective coatings were investigatjcd.

Il Wa3 found that in the um of lead puintj* the mst Hcalc tnvtst be carefully

n?Jnove<j^ i\8 the paint would not p43netratc it but Wijuld flwk off^ leaving

tlie niMt spot beneath. The paint use<i was a resichuil hydrocarbon oil,

^esulling from the manufacture of gas from California asphalt oil. It is

<iiffrrent from the eastern coal tars and has the distinct prop^Tty of pene-

^ting rust and rust scales on the metaL Experience gained from year^ of

I ita use on sheet steel pipe In this locality ih^nionst rates the long duration

r ttf %Ww paint aa a proteuting medium. During cold weather or on cold plat^

I '^ l^ecomes necessan" to heat and dilute this oil tar with distillate, but with

I *'*JTij conditions dilution is unnecessary. All the steel work on the aque-

"*Jei hi painted with 1 his material. lt« cheapness is another distinct feature,

^ it costs but $4,00 per barrel of 50 gal. If is applied to the pipe with

**^8hcs. There are several trade coal tar paints on the market, but their

[ ^^^t m much greater. One gallon of the paint used will rover about 400

•^^ ft. with one coat. The cost of painting with two eoats varies from J cent

I t*^ftquare foot under the most favorable conditionS| to li cents under^tho

I ^Kmt unfavorable conditions/^

372

AMERICAN SEWER AG B PRACTICE

In 1913, over 25 miles of large steel pipe were protected by wruppm M3ksi

them with burlap after being dipped in a tauk of mineral rubbex coati^:^^
The process hiia been developed by the East Jersey Pipe Co. and \^r£k^
described in Engineermg NewSy Nov. 27^ 1013. The burlap atrip ^^
18 in, wide and b put on in a helical fa^hion^ with an overlap of abci^-ut
1 in. The company's specificatioiiB for the covering read as follows:

"After the pipe has been dipped in the mineral rubber coating and *•:-
coating him sufFiciontly set to prevent flow in the subsequent operatioojj ^
shttll be ^Tapped with 10 oz. Calcutta burlap, or equal, which aliall be «:^
into strips 18 in. wide and applied in the following manner: Pipe shall
placed on centers of ii wrapping? machine where it shall be slowly rottit^^*
The burhip, which shall be carried on the reel of a caniage traveling loi^»^
tudiaally during rotation of pipe, sh nil be dmwn from tb? reel by the rev<^— -
injc pipe through a tank containing a hot solution of mineral-rubber p-^
coating, and shall then he wound spirally on the pipe, the burlap being Inpp^^
upon itself to about the width of an inch, the tension of the burlap w
winding being auflficient to cause the burlap to lie close and snug on the pi^
but not enough to strain or tear it. The wrapping shall be kept buck ^
enough from the ends of the pipe to leave the rivet holes accessible and
interfere with the making of the fiehl joints. After the pipe is laid, rivett
calked and tested, the field joints are to be wrapped with one wind of t
burlap which has been immersed in field coating.'*

tt

b«?

-Vv-

aot
the

The Institute of Indii'itrial Heaearch, at Washington^ made soi
investigations of the properties of pipe dipa in 1913, which Dr. A.
Cuahman, the director^ states have given very encouraging reault^ ^

the case of refined coal tar mixed with linaeed oil and a partially solubcz:* *™
basio chromate pigment. Another good class of coatings was nmc^-^^^*^
by cutting gilsonite with distilled wood turpentine^ to which a very smv^- ^^'
proportion of a petroleum with a high boiling point was added to do u^a t*=^
with the brittleness of the gilsonite,

Bitumastic enamel, which had been used for mnny years in nrnm :*►
work, was adopted by the Board of Water Supply of New York, for *^
east-iron water main laid in salt water. It is expensive, about 7 eer *
per square foot, and its use on the pipe mentioned was govMrniti l>v v
following specifications:

"After the pipe ahall have been insjjectcd . , . and all greaae, nil an^^-
paint taken off by means of an appruved chemical remover, both r? - --
and exterior surfaces shall recei\^ one good eoat of bituinastic »'
After dehver>% and as short a time as praciieahle l)efi*re 1^
ahall be gi%*cn a second good coat of bitvniiiistic SL»lution ;<
thereafter a heavy coat of bitumastie enivmel. The ^ilutiuu i
Ainel slmll each be Crtrefully applied, st) tis to cover absolutely
facoa oi the pipe exreptiiig the fnirfuees above nieutiomHl. In«)ide tlie [uj:

WiaAiriil

narks as may be urm voidable pamiiei to the axb of the

The eriftiMcI shall be of such consistence that it will not scale off when

^ sharp blow with a hardwood instmment nor run when the pipe ia

' to the »un. The consistence of the coating shaU be varied as

id necessary with the seaflonal changes of temperature. The coating

luished shall be free from air bubbles and all other imperfections and thk

rhcjitj lew than A in. thick. Aft-er each pipe is plactnl in the hne and ita

flint made, the exposed uncoated portions at the joint shall be coated Uke

xo remainde^r of the pipe and any partA of the coating which may have

tniured wliall be rejmired with enamel or enamel and solution, so aa to

I the coating in perfect condition when the pipe Is eubiuerged.

The stad pipe used as inverted siphons on the Catskill system of

the Kcw York water- works are proietted on the outside by at least 6

in. of 1 : 3: 6 concrete and on the inside by 2 in. or more of cement mortar.

'iTus protection was adopt'ed after a careful examination of steel pipes

*ti service at the time, 1910-11, and nimierous exf>eriments wath various

^^oatings. The steel was pickled in dilute sulphuric acid, washed a!id

l*ainted with lime whitow^ash before it wajs shipped. The completed

f>ipe line was subjected to a hydrostatic test and the leaks calked, and

^hm, while the pressure was on, the outside concrete was placed. The

>n tenor coating wm^ applied in two ways, by the cement gun and by

^CTfiuting between the pipe and metal-covered wooden molds. The

ttcr method waa leas costly than the former and gave satisfactory

ilU. In 1913 the coating waa fomid to bo cracked but not seriously »

»rding to Alfred D, Flinn; after the pipe had stood full of water

Of some time and had then been emptied, the crackn closed almost

pletely.

Mortar liniog was used in 1911 on the Weston aqueduct of the

Tt water-works on SO-in. steel pipe encased in concrete.

i of the pipe was cleaned by a sand blast and then given a

nuth of cement* A Blaw hrting waa then adj usted by means of set screws

tmmghit« shell to give a uniform grouting space of 2 in. inside the pipe.

hia space was hUed wath 1 :2 grout, mixed on a platform moved along

n( the pipe and poured through holes in its crown, other holes

ft to allow air to escape. Two men were kept inside the forms

[g them with mallets, to drive the air out of the grout.

PhiiDes,— A modification of steel pipe is used on the outfall sewer

Kjtft Ltike City. In 1911, 2450 ft. of Maginnis semi-circular steel

u* put in. Tills is 6 ft. 4-1/2 in. in diameter, made of galvanized

xL't^ta, and k carried every 2-1/2 ft. by a 7/16-in. round rot! passing

one end of a crosstie lying on a 4 X IQ-in. longitudinal stringer

I^Ih ' ' ' h, down under the trough and up to the other

,>tt^ ,. rests on a similar stringer on the other side.

*thmy Ktnngertt are supported on concrete posts except at a river crossr*

374

AMERICAN SEWERAGE PRACTICE

1

ing, where wood piles are used. The Magianis flume has been ©mplnv(-vl
extemsively on irrigation work and its special feature ia the joiati 1
made by overlapping the plates, a small bead on the lower plate li i : .
into a groove on the upper plate, A steel rib fits over the joint or. 1 1.
inside and the round carrier rod supports it on the outside; whn
bolts on the ends of the carrier are screwed up, the inner rib ano
carrier hold the plates together firmly. On the Salt Lake City ouUe«
sewer, a few joints leaked a triBe for tw^o days, but were soou ailt^** ::
Corrugated Pipe. — Corrugated pipe have been occasiotmlly mt-d ;
sewerw, as at Taft and Berkeley, Cal., concerning which linea no m*
formation baa been obtained by the authors, and at El Paso, Tct
At the last-mentioned place, the pipe line is a temporary one and iml la
be easily taken to pieces for removal on account of local reaaons »t4t#<l
in Engineering News, April 17, 1913. It was 24 fn. in minimum diaiD*
eter and the corrugations were 1 in. deep and 2-1/2 in. aparts Tbt
pipe was furnished in 30-ft. lengths. Rough gagingfi of the tE'*ch?»!?^
of the pipe when flowing full indicated ilmt it had a coefficient of njg
n of 0.0212 to 0.0222 for use in the Kutter formula: those measuremcDti
were made at a velocity of flow of about 1-1/2 ft. per second. Tb
head which was required for a flow of 5 cu. ft. per second was l.lOfi In
1038 ft. of straight pipe, and 4,37 ft. in 2808 ft. having two ri^l-
angle turiLs with a drop of nearly 3 ft. at one, and a long easy cunrc
at the lower end.

CAST-mON PIPE

Where internal preasurea are heavy or a sower has to be carried thrcnitii

a wall where it is rigidly held, cast-iron pipe are usually laid until the newer
has passed well outside the danger zone. The relatiouj of burrtrAjr
pressure and thickness and the standard lists of cast-iron pipe m
taken up in detail at an earlier point in this chapter. It ' ■
keep in mind, however, that in pipe of large diameter \
such as are likely to be used for sewers, external pressures may h«* :
dangerous than internal pressures. For this reason it is acme ^
desirable to surround the pipe with concrete, which in the ease ot -
over 20 in. in diameter, crossing under streams, serves also to w i:
down the pipe and keep it from rising when empty. Smulirr su
usmilly too hea\^ proportionally to float.

While most of the sewerage uses of caj9t-iron pipe arv zf
siphons and outfalls, they are occasionally empfoycd in cro*^
railroad tracks, aqueducts and like structures which il is 1^
keep protected against ever>' kind of structural danger* For l .,.,
caat-iron sewer used at Tompkins ville, Staten Island, X. Y., is j^^
in Fig. 130. This drains a 47-acre hillside and is likely at itine« to k

Bb^

jm

jH

SEWER PIPE

375

I of 13 ft. In a distance of 535 ft. it croases under tvro main
nger tracks and 24 switch tracks, at deptlis of 2 or 3 ft. This yard
with cars so that the live load on the sewer is likely to be
\kd in addition the yard is located on a, rather soft fill, which
Bcc^ar>^ to use pihng, 12 to 3G ft. long, in order to s\ipj>ort the
»ft a firm stratum. The surface water colUjcting on the yard
DfF in the vitrffied pipe drain beside the sewer in the illustration.
Feast- iron pipe Unes cross a stream on or below the bed of the
important to protect them from injury of every sort, including
lie during floods. In some cases this can be attained by merely lay-

Bipe in a trench, in other cases it is desirable to surround I hem
Irete and in some cases^ where the pipes are supported on piling^
tild^be held in a frame over every pile bent, and by pine blocks

Yttrified Dnatm

q\ Concrete ^^

130. — C'list-iron sewer under railroad yard.

rthem on the cap, so that neither vertical nor horizontal motion of
mrt tit possible. For example, in the crossing of tlie DonKiverat
nto the sewage is carried in two pipe line^, one 3-1/2 and the other
2 ft, in diiinietor. which are spaced 6 ft. apart on centers on pile bents.
' at this crossing is 5 ft. de^p and the tops of the pipfi are 10 ft.
i rivt»T bed. There are two pile bents to each 8 ft. length of pipe,
I each bent is a frame of 3 X lOin. plank, wliich holds the pipe
Ikn the blocks f)olted to the cap of the pileii.

M{K* lines, 42 and 48 in. in diameter, which form the
veruge system of Waterloo, Eiigland, are supported on
4ron jet jiiles 8 ft, long. In a paper published by the In-
Civil Engineera, Mr. Bea Howorth describes the process of

376

AMERICAN SEWERAGE PRACTICE

driving the piles, as follows: The pile was slung vertically into posiiioii
from a foiiT'legged derrick two loga of which were on each side of the
trench; a small winch attached to one pair of the leg3, lifted and lowered
the pile by means of a block and tackle. When the pile was ready to l>e
sutik^ a 2'in. iron pipe was let down the center and coupled to a force
pimi p by means of a hose. A jet of water was then forced down thia pipe,
driving the sand and silt away from below the pile. The pile was now
rotated backward and forward about a quarter of a turn by men
puUinR on the arms; the pile, of course, sank by its own weight, the water
jet driving the sand up through the hoEow center and into the trench,
but it was always kept vertical by a sling from the derrick. As soon a^
the pile was down to its final levels the ground was filled in around the
armi? at the top, in which the pipe rested, and in this running-sand the pile
became perfectly fast and immovable a few minutes after the sinking
was completed,

WOOD-STAVE PIPE

Wood-stave pipe is used in sewerage work mainly in outfalls, owir
to its flexibility and freedom from decay if kept submerged c>onstantly.l
Edwin Duryea has reported, for instance, that at Palo Alto, Cal.* a
12 -in. continuous wood-stave pipe was laid in saturated marsh land for
1 J miles. It was the outfall of the local system, and at times operated
under a head reaching 6 ft., and at other times was but partly filled
After 8 years of tlijs service, the staves were found to be in gc
condition, but the bands were badly corroded and some were entirely
destroyed. In a number of case^ reported in Tran^. Am, Soc, C. E,^
vol. Iviii, p. 65 et seq.^ wood-stave pipe remained in good condition
eJtcept where they were not under sufficient head to keep the pores
the wood saturated. Bruising of the wood in cinching the bands
handling seemed to start localized decay in many cases. The le
durable parts of such a pipe are usually the bands.

There are two kinds of wood-stave pipe, one made by maebit^erv m^
shoym and put together in the trench like other t3rpe9 of pipe, nod
other the so-called continuous stave type made of planks put tosetli
in the trench. The machine-made pipe has staves of uniform Umctli
held together by a helical winding of wire; the 1 1 -i j

st-ave pipe are of different lengths and are held toge d 1

hoops or bands and by strips of No. 12 to No. 14 sheet st^el let into aaw
kerfs at the ends which butt together.

The design of continuous wood-stave pipe tDi-ohfa the 0OMd«rstioii
of the intiiJi] stmin in the bands, due to cinching and th» stnljii ml up
by the pressure of the water and the swelling cif %hc etmvtB^ ihm cookprc^
si\*e strains in the wood, due to the pressure ol ihe bands u|KiatliecK]i*
side sturfaoe and the proesure o( the adjacent «U\nes, and the fkacm qf

SEWER PIPE

377

J due to the pressure of the water. A paper on this subject waa

contribuUtd to Trans, Am, Soc. C. E., June, 1899, by A. L. Adams. As

n, rMuJt of his investigations he recommended the adoption of the di-

memom given in Tuble 126, the spacing of the bands to be determined

I in each case by the engineer to meet the pressures the pipe must carry.

The band spacing on the wood-stave pipe of the Denver Union Water

18 determined by the formula

N = 260DniAS

where N = number of bands per 100 ft, of pipe,
D — inside diameter of pipe in inches,
// *= head of water in feet,
A = seetiotial area of pipe in square inches,
8 — safe tensile strength of steel in pounds per square inch .

Tbccmnpany uses both 12,000 and 15,000 lb, as S, and if these values
substituted in the formula it takes the following forms for bands
d liferent cross-sections:

Diatn. Iiands, in. 3/8

1/2

5/8

3/4

= 1 2.000 lb. DH/5

DH/9

DHIU.l

DUI^A

= 15,000 1b. D///6.4

DH/n.3

DH/18

DH 125.5

Tlie Kpaeing between centers of the bands in inches, /, adopted by
I* L. Ilenny, is determined by the formula

/=

S

PiR+m

bcre S w ns given above, P is the water pressure in pounds per square
jlch, R it^ the iutemal radius in incites, and t is the thickness of the
ives in inches. In Trans. Am, Soc, C, E.j vol. xli, p. 72, he stated
12 in* was the maximum spacing he useti with staves 2 in. thick
blU pipe, and this was reduced to 1 1 and 10 in. as the diameter of
pipe increased. With Ij-in. lumber the maximum spacing was 10
Jn using the fommla it is necessary to make sure that ttie pressure
the bands on the staves does not exceed a safe amount, which Mr.
AH 8tK) lb. pcT square inch of band contact, whereas Mr.
I cd to adopt a sliding scale of values, ranging from 140
per UtwAii inch of band with 3/H-in. rods, to 262 lb. with 7/S-in, rods.
5 equivalent to 747 to 600 lb. per square inch for the same range of
Tlw* usual practice is to estimate this pressure by means of the
fbrmulii^ e = *S/(/^ H- 0* where e is the desired unit pressure and Uie
iber lelt4*r!t represent quantities as previously stated.
[Owing to the necessity uf keeping the wood saturated to the outside
I pipe, in order to prevent decay, it is a positive disadvantage to

^^fa

riMb

^^H 378 AMERICAN SEWERAGE PUACTWE ^H

^^^^H use staves with a greater thickness than is needed to witLstatid t ho M
^^^^m conditionti,

^^^^B The pipe used in the western section of the country are maia
^^^^B Oregon hr or redwood staves, while eaBtern specificationn liav€
^^^^1 mitted white pine, yellow pine and white cedar. In any case, itl
^^^H Birable to employ only absolutely cle^r stock of the highest qualit
^^^H if wood conta.ining sap and pitch is intrmluced into the line, expe
^^^^B shows that an element of dangerouf^ uncertainty will he adn
^^^^1 Wood of close, even texture is preferable to that of a more cooraa
^^^^B acter* The staves are usually milled to bra^u templates, either ixu
^^^^m checked by the engineer, and the um of beaded edgee» formerly
^^^^B favored, has few advocates now except for pipe to be used under
^^^^B heads, which do not require heavj' cinching of the bands. Slight
^^^^^^^ along one edge of the stave probably help to make such a pipe i

^^^^^^V Table 126 -Dimensions of Wood-stave Pipe Details (jVdaM|

Diam. of
pipe, inchei

stock site of
AUven, itieh(»

FiniAbed thick* i
incliM

B«iit ai«!

B>iidoni»|

10
12

14

la

18
20

22
24
27
30
36
42
48
54
60
66
72

U X 4
IJ X4
li X4
2X6
2X6
2X6
2X6
2X6
2X6
2X6
2X6
2X6
2X6
2i X8
3X8
3X8
3 X ft

M

ift

lA

li

If

11

U

lA

li

lA

11

IH

21

21

2A

21

AXA
AXA
AXA

AXA
AXA
AXA

Elliptical

Elliptical

Ellipticjil

EUiptical

Elliptirnl

Elliptical

Round

Hound

Hound

Hound

Hound

Hound

Hound

Hound

Round

Round

Round

^^^^B

The bands used to cinch the staves into a pii)e, being ihe wt
■eature according to experience, should be made of good wrnugUi
and covered with a durable ptunt or heavy varninh of the pipe^ip oi
One end should be upset and have a threjvd rolled in it, and tlie oi
attached in various ways to the coupling shoe by wliich the rtid h\
ioto a band. The l'* cast-iron shoe evolved from «hp i
experienfie with the ac pi[)e of the Denver Union Wnt*?^
and extensively used by the lixceLiior Wowlen Pipe Coi, is pcrbap
favorite tyi?r - — ^.^--v ^ ' ... ,., .jy ^^^^

SEWER PIPE

370

Th« wood-stave outfall sewer built in 1903 at New London, Conn.,
^ig. 131, was typical of such work done in that section of the country at
' * M^ The outlet was submerged 9 ft. below high tide, at the top
. |) slope, iind was located 90€ ft, from shore. The i8-in. outfall
1 UfOO ft. long and terminated at a small cutt'.fj-ba.sin, from which a
I €Hn. sewer ran inland for a distance of 1600 ft» on a 0.1 per cent, grade,
"^rtje entire sewer was submerged at mean high tide and where it pajssed

* " ' the catch basin it was 2-1/2 ft. below high tide, .so that i*. was

• emptied only twice in 24 hours, at low water, when it waa
c;l«aned by a discharge from a large flush tank at the upper end.

This »ewer was laid in a trench excavated in the mud and was cov-
<5r«d to a depth of 2 to*12 ft, with mud. During this work a wood-stave

L5Qddts

^ ' • Otd Rat is to gi\f* Wkiqht - -''^
Fia. VK\, — 'New London outfall sewer.

^fUtfall "^i^wer, built in 1893 of green cypress staves and damaged later by
was uncovered in a number of places and found to be in good
"'ft'litiou, not even the hoojis showing signs of deterioration. Six of these
*ood*MAve outfalls have been laid in New London under the direction of
^ ' If. Richards, engineer and superintendent of the Water and Sewer
^^ptutmnnt. The larger ones have given no trouble, but the smaller
^«i, rti«ivtng the sewage from very small areas which consequently
elocity, have become obstructed liy grease at timea
^ the hoops have been badly corroded.
A H-m. wotKl-stave pipe was built for the outfall of the Ithaca, N. Y.,
*W«i«g|ify«tem| in 1895, The pipe ha<l eleven 3-in. hemlock stavesand

380

AMERICAN SEWERAGE PRACTICE

was much like that at New London, Fig. 131 » being weighted wit
60-lb. steel rails in the same fasliiun. The hoops were 3/4-in, gtilva
iron bands spaced 4 ft. apart. To construct this outfaD, a plat form
wide was built out from the shore line, for a distance of about li
along the line of the outfall. Rollers were placed along this pUi
every 8 ft,, and the stave pipe was put together on these rollers, a l
form of laths being used as a sort of center in this work. When |
100 ft. of pipe had been put together, it was rolled off the end c
platform into the water, after empty oil barrels had been attac^hed
When about a fourth of the outfall liad been built in this way it was ti
into place alongside guide piles. The rails were heax^y enough to sia
pipe w^hen the oil barrels were detached. The four sections of I
werejoiiiGd by oak staves 16 ft. long, encircling the pipe and nailed
w*ith special bands put around the entire joint. This outfall'
abandoned after about 5 years of service, on account of a change ii
method of sewage disposal. During its service, the only faults obst
in it, according to Henr>^ L. Stewart, assistant superintendent of p
w^orks, were a leakage between some of the staves, due to spacinj
hoops too far apart, and a tendency for the hoops to break w*hcn;
were bent into small circles. An inspection of the staves in 1913flh
them to be apparently sound,

Wood*8tave pipe have been extensively used for many years in ti
sewers carried on timber piers. Their lightness and flexibihty an
ticularly desirable in such situations. Usually the pipe are carril
the same piles w^hich support the deck of the bridge, but occasiod
semi-independent benta are driven, as for the 3-1 /2 ft. sewer on Picrl
Philadelphia (Eng, Record^ Feb. 10, 1912). Here pairs of piles onl
centers, the pairs spaced 10 ft. apart, were driven along the axis 0
pier. Each pair of piles wa^ capped ^^ith two 6 X 12-in. clamps, ih
tops being notched to receive them. These cap« were long enough
fastetied on each side of the sewer to other piles than those drivoj
niarily for the sewer* They carried longitudinal 12 X 12*in. etiit
to which the pipe WTre strapped at alt^^rnate intervals of 7 J and 2
the straps were 7/10 X 3 in. with round ends which were carried
through the stringers and held by nuts and w^sshera. The pip©
also held by chocks placed between them and the stringers*
inch staves were used in their construction and these were ha
7/16 X 3-in, semi-circular straps bolted together through lugs on
ends to form hoops. The straps over the piles were made I in. wi<

The largest wood-stave sewers in the United States at this time C
are the twin 00-in. underwater ' ' ' i '

which the effluent from the

delivered into the Black River. These sewers were designed by
W. Hendrick, Chief En^ ' ** ' Baltimore Sewerage O

SEWER PIPE

381

The contractors were permitted to use cypress, redwood, fir, longleaf
yetiow pine or other wood satiHfactory to the engineer, and the staves
were not allowed to be less than 12 ft. long and 2 In. thick nor more than
8 in. wide. The bands were 3/4-in. round bars on 18-in. centers or 5/8
in. bars on a smaller spacing. The twin pipe were laid on two-pile bents
25 ft. apart; the piles were driven until their pomts were at least 10 ft.
below the final location of the bottom of the pipe. Between the two rows
of piles, a trench was excavated deep enough to allow the pipe to be
lowered until their top>s were 2 ft. below the river bottom, where they
were held by 3 X 12-in. caps.

CHAPTER XI
THE DESIGN OF MASONRY SEWERS

The majority of the masonry sewers con.structcd in this count^
have been of circular cross-section, although in some old isj^teo
sewera constructed with an oval or egg-shaped section are to I
Since about 1900 a number of other sections have come into \mi
some of them have found quite general favor. In the following j
graphs the principal types are described and some of their chid i
vantages and disadvajitages discussed.

Circular Section.^The circular section has been used more \
thim any other. It encloses a, given area with the least perimeter i
on that account gives the greatest velocity when flowing haLf*fuD i
full. Under ordinary conditions circular sections are economictl I
the amount of masonry required, although In flat bottom trencher I
under comlitions requiring special foundations, such as piles or t
platforms, additional masonry is required to support the artL
the combined system^ where the tlrj^-weather flow of sewage i» '
small in comparison to the storm- water flow, the velocity for the I
flow^s is greatly reduced in the circular section and on that account 1
section may not be as advantageous as the egg-shaped section.

For sewers under 5 ft. in diameter the circular or egg-shaped ffl
are usually employed in preference to other types*

Egg-shaped Section* — In combined sewem where the drv»*
flow of sewage is small compared with the capacity of tb* > qu

for storm water, or in wanitarj' sewers for a district wl
population is but a small proportion of the ultimate development, <
ideal sewer section is one in which the hydraulic radius remaintK cousti
a*i the depth of flow decreases. It 18 impracticable to obtain the
but the egg-shaped or oval section coined nearer to it than any <
thua far devised.

In some cases the attempt has oeon made to design an egg^b
section to meet special conditions, such as limited head room, or to j
portion the radii of the oval to provide for special variallotw Mn
the normal and maximum flows. This has led to some fwm* wh
have found little favor in this cnnnirv nHhoiiyh m^a'A rxi**i\iii
abroad.

The standard egg-shaped section sliown in 1 lu, i:>2*i, iSo:* «t*-^t^nAi1
England by John PhiUips about 184*^, and has bt*.en used con

382

THE DESIGN OF MASONRY SEWERS

383

-a-

-b-

Phillip» Standard

"Ncw*

• Eg9- Shape,
r

Egg- Shape
. .»
IV

• c-

-d-

5o»tof%

Croton

Horsesho^ Section.

Horseshoe Section

St. toub Honeshoe .

FiQ. 132.— Typical cross-sections of sewers.

381

AMERICAN SEWERAGE PRACTICE

: noraj

since that date without modification. He also designed
egg-shaped section, shown in Fig. 132b, for use where the :
ia extremely small compared with the maximum, but this hi
used so largely. The advantage of the egg-shaped sewer '
dimall flows the depth is greater and the velocity somewhat high^
in a circular sewer of equivalent capacity. This is well ilfustra|
Table 127, showing the comparative depths and velocities

Table 127. — Comparative Velocities m Circular akd
Skwers by Kutter's Formula with n = 0.013

CHrculiir newer 6 ft di»ra. S - 0 00025. Q - (J7,4 cJ*
Eng-^hape •ower of c<iuivttbnt ciipiifity. S * 0,00025, 5 tt. X 7 ft. 0 \n., Q

Quftntity

Rowing in »t"W«»r,

cu, ft. per Bee.

Uaiio of <|uaDtity

fiowiag to cnpacity of

ciroul&r M»W(rr full

Depth of flow iJi feet j

Veloeity, It p

Circulw- I

CirquUr | E^

0.03

0-0005

0.11

0,14

0,24 j (

0.34

0 OO.'i

0.32

0.40

0,57^

0.U7

0.010

0.44

0.56

0.73 ■

l.Ol

0.015

0.53

0.68

0 84

■

1.35

0.020

0.65

0.78

0.91

1

1.7

0 025

0,72

0,90

1 00

1

3,4

0.05

0.96

1.28

1 22

1

6,7

0,10

1,29

1,76

1,48

1

13,5

0.20

1.82

2 61

1 84

1

20.2

0.30

2,27

3,09

2.08

1

27.0

0,40

2.64

3,61

2.25 .

B

33.7

0 . 50

3.00

4.09

2.39

J

40,4

0-60

3.34

4.56

2 50 1 J

47,2

0.70

3,69

5,00

2.59

1

53,9

0,80

4.05

5.40

2.66

1

GO. 7

0.90

4,45

5,85

2.72 J

I

67.4

1.00

4.92

6-36

2,741

I

72,8

I 08

5,64

7.05

2.64^H

07.4

1.0

6,00

7.50

2.;vo J

■

circular sewer and in a q equivalent egg-sliapod sewcr 5 ft. bjj
for various equal flows in each type. For the small flows i
two-tenths of the total capacity of the sewer or [om^ the
egg-shaped sewex is somewhat greater than in the circular^
difference may not be of practical benefit of it^lf, it \^
considered with the incre4iiic in depth, and taken togcthcd
ences make the egg-^iihaped tiewer more de.sirahle^ where|
large sewer is at times very small. The depth of fUi
shaped ucwer is always Kreater than in the cinnilar *»ewer j
titles, and for t
flotution for th-
than whero the dtipth of flow ia bM and thff actual]

THE DESIGN OF MASONRY SEWERS

385

y \em than that computed, because of the obstructions caused
iBd matttsr. Whether or not the advantage in greater velocity
iptU of flow w siiificient to offset the disadvantages mujst be
nod for each particular case.

wcrs 6 ft. in diameter and over, it is doubtfiij if the egg-shapea
IB HuHiciently economical. As may be »ecn by the example
mti in Table 127, the circular sewer has a vertical height of 6 ft-^
tule Ihe egg-shaped sewer requirea a height of 7 ft. 6 in. On the other
i»nd» the hori/.ontal diameter is decrea^^ed from 6 ft. in the circular, to
> ft. in the egg-shaf>ed, which makes it po^isible to con.struct the sewer
tt narrtiwc'T trench. In deep trenches there will be a saving in total
iftvation by using the egg-shaped sewer, due to the decrease in width
h, which may more than offset the small increase in depth,
egg-shaped section has the disadvantages, however, of being
ble, more liable to crack, requiring more masonry, and in general
ore difficult to construct. In verj^ stiff soil or in rock it is some-
poasihle to excavate the bottom of the trench to conform to the
of the invert of the sewer, but in general, in yielding soil or
foundations are poor, requiring piles or timber platforms, the
ped sect ion requires considerable masonry backing under the
to support the arch, even more than in the case of the cir-
sewer* For this reason the egg-shaped section will be found in
ly cases much more expensive than the circular type and far more ex-
ive i\mu some of the other types which are discussed further on.
Section. — This section was used extensively on the Massa-
H North Metropolitan sewerage system, under the direction
Howard A, Carson. Its principal advantage is tn the fact that
-o nearly in shape to the available space inside the
ring in earth tunnels, as may be seen in Fig. 157, The
m IB strong in that the hue of resistance keeps well within the arch
, has* fairly good hydraulic properties and carries the center of
tif the wetted area nnich lower with respect to the height than the
1. This last fact may be of some advantage in locating
nons at a lower elevation, or in raising the invert- of the
Thia, of course, contemplates the possible operation of the
nnder a head at times when the main sewer is running
Tlwrt ftTo cases wiicre this may be a practical scheme, but in
Ue avoified. It is of material advantage, however,
difference in water level is small. A larger quantity
for a given inerease in depth than is the case with tiie
Thn catenary section has been but little used of late

—This section, closely resembling the circular in
'«'^ was also used to some extent on the North Metro*

mm

386

AMERICAN SEWERAGE PRACTICE

poUtan sewerage system in Massachusetts; see Fig. 135, page «^S
horizontal diameter is about 17 per cent, less and the verticid *
about 8 per cent, raorc than the diaraet^er of the equivalent circle, i
that account it reiiuire^ less width of trench than the circuUr i
Its greater height may be disadvantageous except under ^pccii
ditions, because of the increased quantity of excavation requ
the sewers are located oq the basis of the crown grade. As maj
peeled, the hytlraulic properties are not far different from
circular section. The Gothic or pointed arch is somewhat sir
the semi-circular This section is not in general use at the ]
time, although it hiiK advantages for special cases.

Basket-handle Section.— This section, Fig. 159, waa de
Howard A. Carbon on the Massachusetts North Metrojx
work, ami has been used to a large extent oa that system, and i
extent in other places. It is so nearly a horse-shoe tyjK? LhiH
hard to draw a definite line between the two. Concerning \h
section, Fig. 159b, Mr. Carson states in his Third Annual Eep
Metropolitan Sewerage Commission, for the year ending Scpt^
the following:

*'The horiEontal diameter is about 6 per cent, less than ih** \ r rt«f7i]
arch is slightly poiotcd and the invert is flatter than a semi
shape the area, perimeter and the theoretical velacitr wbti
than one-aixth full differ but little from the corresponding vk
circle having the same height. In actual construction »
that ujsu.^lly obtain on our work, this shape is more
completed, than a circular shape. It requires more c::
vent injury to the invert, while the latter is being coti-

In general the basket-handle section has about the bhqip i
and disadvantages as the horse-shoe tj'pe, dascribed next, td
merges so that it is difficult to determine whether son i
classed as basket-handle or hor^-shoe. The invert v jr|

curve and rounded corners between the side walls and in*«t,l
some advantage for strength, but the diflference is so iligBj
difficulties of construction so much greater than tlie focfi \
ployed in the horse-shoe type that it is not now ir
may abo !>e some slight advantage in having th*
greater strength and somewhat greater ease in remcrrBf'
arch forms.

Horse -shoe Section. — For large sewers it is probahlntlMii
circular section this has been more v
Many horse-shoe sections have been d* ^
tions, a few of which are shown in Figs. 160, UTl aj
springing line the horse-shoe section has a semi'-circLuxu

THE DESrON OF ^fASONRy SEWERS

387

low the springing line are vertical or incline inward, some-
m with ji plain and sometimes with a curved surface. The surface of
invert varies in section from a horizontal line to a circular or para-
are, or other design calculated to concentrate the low flows near
center of the invert*

ie scrent advantage of thia type of sewer is that it conforms to the
of the bottom of the trench &» usually excavated, and on that ac-
t does not require the large increase in masonry backing to sustain
^lutih, which is needed with circular and egg-shaped sewers built in
but the firmest of soil or rock. Another advantage ia that for a
1th or horizontal diameter the sewer raa^* be designed with less
[Jit as a horse-^hoe and still have the same carrying capacity as the
lihir. Wliere the depth of the sewer below the surface is controlled
'he grade at the crown, there would be a consequent saving in excava-
becnuse of the decrease in depth. Where only a restricted amount
A room is available, the wide horse-shoe type can often be used to
lintitge. In yielding soil where it is necessary to spread the founda-
thc horse-shoe type can be used in an economical manner, because
he saving of masonry in the invert. The limit of the horseshoe see-
along this line is the semi-circular section, in reality a horse-ehoe
ion without side walla.
%e chief diBadvantage of the horse-shoe section is that unless the
walls are made he^vy the stability of the arch must de|>end to some
tni on the ability of tlic earth backfilling to resist the lateral thrust
the arch transmitted to the side walls near the springing line* The
ct of th«? side walls is to increase greatly the bending moment at
crowD and center of invert, especially the latter. If the sewer is
1 uf monolithic reinforced concrete, with continuous reinforc-
f^ n i t ho center of the invert to the crown of the sewer, the bend-

moment developed at the crown and invert center will be very severe
Ifdjio the bending moment at the spmnging line.

the horso-shoe section is constructed in rock cut» so that the invert
haj&e nf the sido walls rnn be built directly on the rock the conditions
1 |je gn^ntiy altered and the line of thrust will stay witliin the section
h more readily than if the sewer is constructed in compressible
, with the whole structure acting as an elastic arch from the center
Ihe invert to the crown. In the case of brick arches this necessitates
eonstructitin of comparatively heavy side walls or abutments.
W1I9 of reinforcing metal in concrete has helped to remedy this
but even with heavily reinforced sections oasea are known
tins arch tracked on the inside at the crown and on the outside
w qiiiirti^r |K)ints or down toward the springing line* While this
fftilure, it was objectionable from the point of view of
t ing of the stoel reinforcing metal. It is hard to conceive

38S

AMERICAN SEWERAGE PRACTICE

of tlie passive reaistance of the earth, especially in newly backl
trenches^ being brought into action without some movement o!
concrete to oompacit the particles of earth next to the masonry.
eflFect of such movement on the stability of brick arches is well
trat43d in a paper by Alphonse Fteley on "Stability of Brick Condi
Jour, Assoc. Engr. Soc., Feb., 1883,

Senii-elUptical Section. — The arch of this section is either a true
ellipse or is made up of three circular arcs thus approximating the
ellipse. As the center uf cavity of the wetted area is lower down
respect to the crown than in the circular sewer, the normal flow
will be much lower which, as mentioned in the discussion of the cat<i
section, may be of considerable advantage* (See Fig, 163, page

The oliief advantage of this type of sewer is that the shape ol
arch more nearly coincides with the Unc of resistance of the aruh
actual working conditions than is the case with other sections. BcO
of this the arch section can be made relatively tliin and stiU keep
stresses in the masonry within allowable limits. The section
pendent to only a small extent on the lateral pressure of the eart
prevent failure, and does not depend upon the pajssive pressuj
natural resistance of tlie earth filling on the sides, as ijs the case,
often, with the horse-shoe type. The fact that the arch Is of thint
tion and goes nearly to the invert line, makes it more necessary to d<
and construct the invert, of the semi-elliptical tj'pe, so as to distr
the presHure over a sufficiently large area.

This section deiJends to a larger extent 6n the stability of the ii
than is the case with the sections previously mentioned. Who
semi-elliptical section is constructed in compressible soil and thetftrui
is built monolithic, with reinforcing bars running continuously froi
center of the invert to the crown of the sewer, there will be a large
ing moment at the center of the invert. Under such foundation
ditions, the invert should be ntade as thick as the arch at thespril
line and should be heavily reinforced to withstand the stresses. I
this is done cracks are likely to occur at the center of the invorti

As in the horae-shoe type, the invert of the semi-elliptical ac
readily conforms to the bottom of the trench excavation, and foi
reason the quantity of masonry below the springing line is not exca

This section is not as advantageous for low flows as the circula
cause of the wide and shallow invert in which there is a ven»' low \'eli
However, for sewers where the quantity to \ye carried is not stibji
wide variations and the normal flow is hb much as one-third of the
capacity of the s^^wer, this disadvantage may be neglecir»d.
hydraulic properties of the semiHaUiptical section are very good in p
whicbi with the vury desiral»le structural fentun^s, make tliis lyp^
of the bout for sewers over 6 ft, in diameter.

THE DESIGN OF MASONRY SEWERS

389

l^anibolic or Delta Section.^ — ^This type of sewer was developed by
J^Arotw H, Fuertcs in eoiinectioii with the design of the i^cweragc system
^^r Santos, Brazil, briefly described in Eng\ Rirord^ Mareh 17, 1894.
i*t J 902 he designed a Bimilar section for Harrisburg, Pa., shown in Fig.

The »ewer section is nearly triangular in shape, the arch being a
p^arabola and the invert a short circular arc with side slopes of about
3 horizontal to 1 vertical. The section shown has a somewhat larger
o^n-rrjHnu Citpacity than that of a circular .sectiau of the same height. It ia
oth eeonoinical and strong and has the added advantage that the
ormai flow hne is lower than in the circular section. This is e8|>ecially
"V^aluAble. in districts where the available fall is limited, as in cities where
^^lo cflTcjat of tide water requires the sewers to be built in shallow cut.
TTli© edaping invert is well adapted for low flows. In this section, as in
t. He scmi-cUiptical t\T>e, the shape of the arch very nearly coincides with
^li£ line of arch resistance, which results in a very strong section. It
faiAS the disadvantage as compared with the semi-elliptical type, how-
ever, of requiring a wider apace for equal capacity and height, because of
^%ie pointed arch. For locatiouj^ where there is but little deiith of excava-
^ioa, afl in crossing low land, the section has a further advantage because
t.\ici wide space makes it potjsible to construct the foundation to better
cmI vantage and the greater carrying capacity below the springing line
luftkcs it poK-sible to build a section of less height than in the ca.se of the
circular sewer, and where the sewer has to be covered by an embankment
'\iui tavolves a smaUer quantity of earth work.

Elliptical Section. — A few sewers have been constructed in this
OHintry with a true elliptical section, see Fig. 15S, some with the longer
I l1 and others with it horizontal. This section is unlike the

•^ .j:i tiud tj'pe in that both above and below the springing line, it

'^ *fl approximation to a portion of an ellipse* Unless the excavation is

ry firm soil, there will be additional masonry backing required

punches to suppoil the arch, as in the case of the egg-shaped

I and tliis is usually an objection from the point of view of economy

nnry. In general, this shape is difticult to construct and because

na HO few points to commend the section, it has not been brought

. Section. ^ — In cases where the width of trench is limited and
nt head room is available to build a sewer whose vertical diameter
,. -My greater tlum the horizontal, the U-«hape section has some

*' . See Fig. lG8e and f. The hydraulic properties of the

BecUui Mi Fig. i<)8e are fairly good until it becomes filled, when the
bydrauJic mean radius becomes materially reduced due to the addition of
tim mdih of tho slab roof to the wetted perimeter. The invert ia well
•dimpled to maintain good velocities for tow flows. It also haa the

■IfiiMii

800

AMERICAN SEWERAGE PRACTICE

advantage, because of the pointed shape, of offeriug a little Jeai4 difBc
to the withdmwal of forms than the circular invert. In proportion i
its area it requires considerable masonr>^ and on that arcouut i» \
economical for large sewers, but for sewers in the vicinity of 3 ft, j
diameter, it doubtle^ss has advantages for special conditions.

Rectangular Section.— This type has been used for many years i
the head room or side room in the trench was limited, but more i
the rectangular section has been used for main lines because of i
simpliJied form work, easy eonstruction, economy of space in tk
trench, and economy of mason rv', and also because of ita exot^llrirt
h>'draulic properties at all depths previous to the flat top becoming irri.
As may be seen from the diagram of hydraulic elements, Fig. 144*
the velocity and discharge are relatively large just 1m f ;
flat top 13 wet, but decrease very suddenly as soon as ii
perimeter is increased and the hydraulic radius decrejiacd \^y •
wotting of the top. On this account it is customary in designing u-^
tangular sections to allow an air space above the maximum flow liiM? of
from 3 to 12 in., depending upon the size of the sewer and Xhfi
amount of head room available.

Where the trench is in deep rock cut, this type can be hskI lo
great advantage, as is pointed out by W. W- Homer in Engintm^
NewSf Sept. 5, 1912. With a narrow, high section, the width of ex-
cavation can be materially reduced, often more than enough to '^^
set the increase in depth of trench required. The hydiaulic proi
erties of the section become ]e«?8 favorable as the ratio cf the Imiih'
to the width increases; Mr* Horner found the economical ratio to Ik*
between 1.5 and 2. A section of this type is shown in Fig. ni5h.
The u.«mal form of rectangular section has a greater width than bcij:!'
as may be seen in Fig. 167. Thm section requires careful dcsigitiiig
to insure its stability. The flat slab top must be designed as a beam l<»
carr>" the earth load and the side walls must be strong enough to tm^
the lateral earth pressure. If the top ia built in the form of a '^•^''
arch, the side walls must be strengthened to carr>' the thrust of thi' *ri ^'

In some cases the flat top has been constructed of I-beams ciita>< '^
in concrete, but tliis method ia not economical of steel as the I-bowi»*
are designed to carry the load while the concrete merely arts a* *
filler between the beams and as a protection to the steeL TKiS^
method, although not economical of steely has the advantage of
ing it possible to complete the sewer and backfill the trench m(rt
quickly than where the roof ia a slab reinforced unth bars. The ^t(
beams can be placed very easily and quickly and do not re^
constant inspection, as is the case with slaJjs reinforced '
It is claimed that in some oases this case of construction will otfjtet ttt
additional cost of the stoel, and in many cases where a large scwor I

built iQ a congested district, itiaof considerable advantage to be able to
Uckfill the trench ^ith the least possible delay.

The V-shaped invert is frequently used with the rectangular sect ion
01} jw'cotmt of its suitability for low flows.

Semi -circular Section. — Tiiis type of sewer, examples of which are
shown in I'ig, 164, has been employed rather extensively in New York
city and vicinity. Its most frequent use has been for outfall sewers
* ■ f tng low land, where the natural surface of the ground is largeJy
the top of the sewer arch and in places even below the invert.
i ijc utiier arched sections, the invert must be firm and well designed
'» ^ipport the tlirust of the arch. Two of these sections are often
built tfidt* by side as twin sewers, instead of one large sewer, in order to
ttvc head room.

Afl u rule, the section requires a larger amount of masonry for its
Ci|«dty than some of the other types. The hydraulic properties are
DOt so advantageous as those of the rectangular section, which, in the
ticinity of New York City, has been used largely to replace the 6emi-
' ir section. The semi-circular section requires a wider trench
'u>ne cxteuaive foundations for equal capacity and height than most
oi the other types.

Sections with Cunette. — Various types of sewers have been con-

ftruftcd with a Sfjecial dry-weather channel or cunette in the invert.

■\K\ although used extensively in France and Germany, has been

, v^-d but little in the United States. The most notable example
« ia Iho trunk sewers at Washington, D. C, Fig. 168c.

This miction requires additional masonry in the invert and a greater
^'\M\ of trench, but hfw the advantage of prcn-iding a good channel
' Inch aelf-clean&ing velocities may be maintained when the flow

Dciuble and Triple Sections.— Where outfall sewers are located ia

^Kirliy srttled districts, and the available head room is seriously

I ■'''i I I'll, it sometimes is of great advantage to divide the section up

' ' ^vo or more waterwa}^ joined together side by side in one struc*

^ -J ^ In other cai^es, where a storm- water sewer is constructed above or

Wow A larffc sanitary sewer, it may be more economical to build both

I ructure, one over the other. Representative types

ro shovs'n in Figs, 170, 171 and 172.

SELECTION OF TYPE OF SEWER

; of the typt* of se\>'er depends upon a number of condi-

fi must be carefully considered and balaticed in the choice

ut ihjt bt»t tyjje to build. In general, that sewer is the best which, for

the l^aift cost ptir linear foot, mil be easy to maintain in operation and

iMi

^^M 392 AMERICAN SEWERAGE PRACTICE ^^|

^^H will have the requisite stability to withstand the external and intenul
^^H forces. In the following paragraphs a number of the principal ileou
^^H to be considered are enumerated in detail.

^^H HydrauMc Elements.— The theoretically beat cros^-eectioQ for i
^^H sewer^ from the point of view of bydraulica, T^ith a given gn* '
^^H and carr\'ing a imifomi quantity of water per unit of time, is tht
^^H circle for an open channel and circle for a closed channel, both rimiimg
^^H full ; because the hydraulic mean radius, r^ hiis its greatest value for tbo«
^^H sections and consequently the empirical coefficient, c, in the Cheiy
^^H formula v = cy/(rR) for velocity of flow, is greatest.
^^H This theoretical advantage is somewhat reduced by the fact that
^^H the flow in sewers is not uniform but is constantly changing in deptli,

■

^^^^^ and therefore
^^H circular sectic
^^H In some caae^
^^H V-shiLped inv
^^H minimum veh
^^H of sewage, th
^^^^^ the invert to

^^^^^ becomes grac
^^H two convergii
^^H junction, bee
^^^^_^ the depth of

j^

1

/ ^

5n

^s

f

j\S

^

/

i

^- \~-

\

lk<

y

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4

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'^r

'^

w

> f

r^,*-

J

/

/

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;^^

//

/

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)r

J

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«p

w

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A

/

^

^

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4

/

^

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f^

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^y

i

^

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"K

^

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rfH

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it

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. C

n
) 1

ei

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-i 02 0,^ 0* as 0,^ 0.7 Q% M 1,0 IV 12
itja ol Hydmulk Elements d filled Segment Hil*io»e of Cnttre Section

raulic elements of circular section by Kutter

K>5; D - 1 ft. Arctt - 0,7».'tD»: Welled J'orimoier
UydmuliG Kadiufl - il/l^D,

e minimum velocity is an impor^
\ not as advantageous as the egg >\^- .
small semi-circular channel has been cons
to carr>' the minimum flow. Assumin
y' is to be maintained with a given minimi
ameter of the small semi-circular channel
y tins flow can be readily comput4?d,
ill quantities of sewage the diameter of th<
y smaller until finally the invert, inste*
lopes ydi\\ a doprcHHcd *iemi-circular chac
B actually a V-shaped section* In this
sewage and B is the angle between th*" ^1

15

f lire. 1 ^^*

trucUnl ia *
g a ptfWin

im qUADUtJ

requineJia

B semt-
d of hi
mel M ,

ease 4^^H

THE DESIGN OF MASONRY SEWERS

393

I and the horizontal, the cross-section, A,ish^ cot 5. The wetted
Bitter^ p, IB 2h /fiin B and the hydrauhc mean radius r =» '\/(0.25 vl X

uu

p^

TJ

"^

T

^

^

T

K

^

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03

m

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"—

L

QjO QJ QZ 03 04 OJ 01 07 09 09 10 U
RoHoof Itte HY<;iraulK: Elemertti oTttte Frited 5f ^meM
to tho*« (yf the tn+ire Sedion.

It

Fia. 134. — Hycbaulic elements of egg-shaped section.

|0.0|£; . . 1/1,600; // - 4 ft.: D - 6 ft, - 1,254 dinrn. «quiv, circU;; // - 0.83<l
■ •*' ^ eqtiir. circlw; A - 1.1485 m - 0,5l05i>>; R - 0.2897/7 - O.I931i>.

LO

J as
I a?
|0J
I OS

Sat

OO 01 0? 03 04 OS 0.6 07 U 09 10 U I

Ratio of the Hydfdulic Elements aTthe Fillwl Segmen.

♦othoteof tht Entire Section

Fia. 135,— Hydraulic elements of gothic section.
• - 1 L50(J; M m A ft; Horiiontftl dwmeU^r * // - O 1^167 dUm. cquiv.
r . /> « l.l066di&m.eqmv.elrde:Aroa « 0.9«a4//» - O.I»5M/>n

''S^ Jl

jTtv

I^^v, ^

lyl \

jt- N^ i

~ /%^ x^

^? V ^^X

^^^ 4-

f" ^ [^1^

%^W^ 4

Z \ Z'^^

- ^"^^ /

1 Q

_^'2 C

,

^^- X^-

[i, ^i

^ L

1- .i-^-.-^t --^^

'- J -

1 =tj^ ^

x/5

j5 -

- -,1^2

I ^it

ji>'^ :^

$ yV^ )

-f'^

i V2 r /i i

?*

;z2 : / ^-?i

jS'^ / .--"^ 1

ffC ^rs:^" 4

K^>-r r -{

kJB), By this expre^on, the value of r is greatest when B is
[lir wheti the two slopea of the invert form a right angle*

invert with the circular arc at the junction has been

^^B . 394 AMERICAN SEWERAGE PRACTICE ^M

^^^m uaed to advantage with the rectanguhir sewer section an^jJ
^^^H Sonne of the other types. ^H
^^^^^^> Where the normal flow is equal to one-third or more of thcnH

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»o thoM rf ti>e tntire Section, ^H

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137- — HydmuUc deiocDt

Xrm - O.7UffT70«j K «

type u the best from tl
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r the seirer and aagr di

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a of i^U^eoary aeeijooj^l
mmift « H • l.Oiidiaii^H
0.331720. ^H

be pQinl cf view of i|taH
r nmsidmitioits vt^|
pUila aooie oihtf Igr^H

TUB DESfOH OF MASONRY SBWBRS

p com|)aLrinK ono section mth aiiothor, it Is important to study the
I between the depth of flow and the corresponding velocity and

10

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0X3 0,1 at 0.1 0.4 0,5 0.6 0.7 0.1 0.S 1^ 1.1 1.2
Ratio of Hydrauiic Etemenh of FrlledSef^mcfYftotfioMcif ErtireSec^on

138. — Hydraulic elements of horseslioe sectian> Wachuaett type, by
Kutters fonniila,

"0 013; , - 0.0003; /) * 7 ft; HoriiontftI tliameler. // » 7 ft. 8 in.; Aren - 44 74
hmo^ ^^^*'' ^**^**^ perLtuetur - SM.2(V ft. - 3,4Gtii*; HydmaUtr radliu - 1.K41

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Hotio of Hydmulic Elemtnt* of Filled Stgrrttrrt+oltwieof Ertf!* Stcticm

iW- — Hydraulic elements of l>:>uisville semi-elliptic section by Kutter'a
formula.

0.0D03; D - 71 ft,; Ari» - 0 7»5rj»: Wotted peninutrt • 3.3Q£>;
llvrjmulb rttdiiia - 0 242/5.

?•- The iliagri^Trt!^ shown in Figs, 133 to 145 give, for each i»f the
1 ty|x>« uf conduits, the ratio of each of the three hydraulic elo-

^^^^PPUP AMERICAN SEWERAGE PRACTICE ^^H

^^^^H menta area, mean velocity and discharge* of the filled se^rmcDt to^^f
^^^^^1 of the entire section, corresponding to any ratio of depth of flow t<^|

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^^^^V Rat^o of HydrouUc Clement* 0l niledSe9Tmiif loiNwtQftEmtrt 5«dfaii ^^H

^^^^^H Fig. 140.^ — Hydraulic elements of apedjU seiiu-elliptical section by KqIM
^^^^^H foriuula.

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Ratio 0

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iffiie Hydnctulk; Ektntnh offheftlM
K Itiote of ^ Efihrt ScehoA .

elements uf Gregory's scm

- O,0O0d.J> - iOU,;'Arw -

e 128 giv«j culditiotiaJ da
. A rn cmg o t lier daia« th

U regnrditif theteM
e table iivcsei the i«^JH

*r«i'^»>-« in timiui 13^9

THE DESIGN OF MASONRY SEWERS

397

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398

AMERICAN SEWERAGE PRACTICE

00

ai 02 03 Q4 0.5 06 a7 08 Q9 W U

Ratio of Hydraulic Elements of the Filled Segment

to those of the Entine Section.

\Z

^^^H 142

— Hydraulic elements of parabolic aectian. ^^^H
n - 7(i.4io,;Afe» -.0.7Mi5*:Hydnnilior»dii» - O.^SO^H

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Rotio of the Hydro
to tho3<

fio. 143.— Mydmulk
1 - 0.002:1) • :iH.oit

0506 07 080910 11 t^C
Lilic Bcmentaof rhe FiTI«5d Segmanf
I of the Entire Section,

! tiietntJnti* of UtilmiKHl sections,
ut Ann » 0.fl43ai>9; Itydniulk r»diu« - i

*-)9J^^H

THE DESiON OF MASONHY SEWERS

399

riM^tcal dimneter, and the relative value of the vertical diameter of the
seotioi] in terms of the diameter of the equivalejit circular section. By

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ftatio Off t1]p Hydrowk Elcmcnti of the Filled Segment to
fhoae of the Entire Section.

Fio. 144. — Hydraulic elemonts of rectangular section,
n • 0,013; « - OCXfll /> « 6 ft.

L3

'Qfl QJ 02 G3 Q4 05 06 a? Ota a9 10 U 12

Rfft»o «f Hydroultc Elements of the Fitfcd Segment to

those of the Entire Section.

io* \\h. — UydmuUc elcmcntg of seiniH^irculiir 8<*ctian,

- O rnS: • m I) 001, /? I- 0 ft li \x\\ Af»ft - 1 20t»7L»\ UyilrHuhf raUiu* - O,2040/>

ivaleot wtction i« meant that aociion which has the same carrying
■pttcity for a ip veo sixi*, i^lope and friction factor, but not the same area.

400

AMERICAN SEWERAGE PRACTICE

The table, also givea the actual size, slope and friction factor upon wliich
the table and curves were computed, which, although strictly correct
only for the data giVen, are auffieiently cloae for other sizes, dopea aud
friction factors to be of general use, and as a rule the diffej-ence may b«
n^lected.

That there can be a sHght difference in the hydraulic elements for
various depths of flow, depending on the size of the section for which the
diagram is computed, is shown by the first two lines of Table 128. Thu
first line gives some of the hydraulic elements of a circular section badcd
on a 12-im pipe where s - 0,005 and n = O.Olo, The second line w»s
computed on the basis of a circular section 7 ft, 6 in, in diameter;
a — 0.0003, and n = 0.013. The change in the value of n was nmdr*
on account of the authors' practice which assumes 0,015 for pi|>e -
and 0.013 for concrete sewers. The slopes were also changed in ord : .
approximate the slopes usually adopted in practice for the respective
sizes.

As previously stated, that section is the best which for varying depths
of flow maintains the hydraulic mean radius njost nearly conutant.

Where high velocities occur another elemeni is introduced in the way
of erosion of the invert and sides of the sewer, which may require special
construction to prevent serious wear and ultimate destruction.

Construction and Available Space.^-Thc method of constructioo ol
a sewer, whether in open cut or in tunnel may have an important
influence on the selection of the type. In tunnel work, especially, it is
desirable to have a section which will utilize to the best advimtagi? ail
of the space inside the tunnel bracing. In earth tunn'
common fonn of timbering is used^ the catenary or sen jt
tions conform readily to the available space. In rock timnels^ the txr^-
oular or horse-shoe sections are apt to be more advantageouji. If tlie
sewer is built in open cut, the section vdW be influenced by its ability
to carr>^ the earth loads.

Where the excavation is in rock or firm soil, it is possible to shape
the bottom of the trench to confonn to the shajie of the ixivwi uf tlie
sewer and thereby save considerable thickness of masonry for
types as the circular or egg-shaped sections. If the cxcavalioi
soft material, where the bottom of the trench must necesaarily . -i it
or if the sewer \b to be built on pUes or a timber platform, coii^idi rui^k
additional masonrj'- will be required for the circular or egg^shjiped ^cweni,
but this can be avoided by using one of the other typrs.

The amount of space available for a sewer may l>e exceedingjy ItmitixL
Sometimes the head room is limited bccaiwe of the proximity of llw
grade of the sewer to the surface of the street, sometimes the iridr - - —
is hmtt^d because of adjacent structures, and thrrn agiiin the avi
depth may be limited on account of tide water or other ciroiuiist4uioo^

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iieo control the allowable depth of tht^ hytlraulic icrade line. The

Pt4ing:ular ijection has proved one of the mo8t uyeful for^tijcfi conditions?*

Jthough the horse-alioe section, with the horizontal or vertical diameters

ijusted to meet the conditions, haa been largely used. In a few cajjej^

the fuD elli{>tical section has also been used in restricted placea. Where

hydrauh*: grade line depth ia limited, it ia desirable to use a sewer

tioo whit*h will rarry the maximum and minimum flows with thr

s»t variation in depth of flow. The catenary, parabolic, semi-ellipticul

[id rt3ciaugii!ar secttona are especially suitable for this purpose, as the

Biiter of gravity of the wetted area is comparatively low down from

^he crown in contrast to the circular section. The semi-circular section

also proved useful in this connection, although the rectanguliLr

<!tjou is being used instead in the more recent work of this character.

Cost of Excavation and Materials, ^-The cost of excavation required

iy one tyije as compared witii ntiuther should be carefidly considered,

ir if the excavation is in earth in a deep treuch, it will probably be

liiMiper to use a narrower deejKT section and thereby save conaiderabli

idth of excavation, even though the depth of excavation be sUghtl}-

«1. This will be especially true in a deep rock trench where if

lound of advantage to use a narrow rectangular section havin^j,

height 1^1/2 to 2 times the width. Fur a sewer built in very shallow

it, or practically on the surface of the ground, a wider section will be

ivAntageous, because little additional cost is incurred by increasing

. hereas greater depth may increase materially the cost of ex-

iu Furthermore the cost of an embankment over a wide »ec-

ioQ will generally be leas, because of reduced height and narrower

pi<ic slopea. The parabolic or delta section is especially useful for croas'

low lands where the sewer is largely out of the ground and must be

prt*d by an embankement. The semi-circular section has also been

i used for this same purpose, but haa been superseded more recently

y ilie rectangular section, having a width about 1-1/2 times ita

beight.

Ill former years a great many sewers were constructed of quarry
tone or large cobbles, but in recent years other materials have proved
exiiensive and better adapted to tliis type of construction and very
sewers are now built in this manner. The cost of brick varies
lily rn different locaLitie^^ and this may influence to a large extent
\ type of construction selected. In general, concrete is more desirabh'
I brick, but where brick masonry can be had much cheaper than con-
crete it may he advisable to build the sewer of brick. The object in
signing a aewer section should be to obtain one in which the quantity
|of the maaonrv* and other materials is a minimum consistent with the
cqiiiaite stabiUty» hydraulic properties and other considerations.
For scwors in which the normal flow id at least one*third of the

2d

402

AMERICAN SEWERAGE PRACTICE

maximum flow, it has been found that the semi-eUiptical section b v|
economical m maaoary, and at the same time provides for the oti
requirements.

Stability, — Where a sewer is constructed in open trench, the artruc
must bo desip^ned to carry the earth or trt!neh load as well a** any suji
imposed load. The circular arch fa not aa strong aa either the CotJi
the paraboliCi or the semi-elliptical arch. The semi-circular
depends to a great extent upon the lateral preaaure of the sides of I
trench and also to a certain extent on the lateral resistance or po^i^
pressure of the earth backfilling, although this Cfui be obvtatiMi
increasing the thickness of the side walls or abutments. The dcn
circular sections obviate part of this difficulty by omitting the 91^
walla and resting the springing line of the arch directly on the invert
foundation. In a rock trench the resistance of the sides of the trench j
80 great that the side walls of the sewer can be greatly reduced in tliic
neaSj the thrust of the arch being carried directly into the walls o( I
trench. In this latter case a very flat arch can be used to advantage.

Imperviousness. — ^ Where a sewer is to be constructed under a rh
bed or below the water table, it may be of particular importance ^^^
the walls of the sewer to be impervious. To this end, if the sewe
built of concrete, it is desirable to insert longitudinal reinforcing Ua
the concrete, with a total area of 0.2 to 0.4 per cent, of the aectional j
of the concrete in order to distribute the stress throughout tli-
the sewer barrel and there!))' prevent the formation of large ci
would permit leakage. Unless the cracks are ver>- small there may
some danger of corrosion due to the water passing through them 1
coming in contact ^ith the reinforcement. This might in time wea
the jMlrurture.

Wliile the possibility of leakage or infiltration does not ordinar
determine the shape of the waterway of a sewer, it is worthy of comid*
ation when the selection is tp be made. For example, ii a aewcr »*H
be built below the water table it may be well to adopt a section wh
least likely to crack, whereas under other conditions the advantn
diflFcrent section might be sufficiently great to warrant it^
though small arch cracks are to be expected. The stability of €fip
horaeshoe section depends to a certain extent on the lateral pr^m\sr^ (if
the cATth backfilling, and on that account, the semi-circular arch is apt
tocrack and may produce unsatisfactory conditions, not on'
of leakage into the sewer, but especiiillv un ntcount of the riL-^r
steel reiuforoement.

SELECTION OF SIZE OF SEWER

In Chapters V and VI II t;

THE DESIGN OF MASONRY SEWERS

403

In determming the size of sewer to carry this estimated
additional factor of safety ia often allowed by computing
flowing less than completely full, as one-half or two-thirds
[an allowance doea not seem to be logical in most cases', for
to the quantity of sewage produced and the hourly,
1 aeaaooaJ variations should be provided for in estimating these
m, the sewer being designed to carr>^ them without further allow-
Upacity corresponding to the maximum estimated quantity

Df rectangular and U-shaped sewers, and to a less extent
should always be based on the maximum capacity of the
kot upon its capacity when completely full. As can be seen
P43 luid 144, both the velocity and discharge arc materially
[»n the inside perimeter of the aewer becomes completely
[to the reduction in the hj^draulie mean radius. Sewers of
should alw^ays be designed with an air spai^e at the top,
r may develop their maximum capacity.

ulic I>iagrams and Tables.— Diagrams giving the discharge of
«>nduitH can be used to compute the velocity and discharge in
Hlonduits of other shapes, provided the hydraulic mean radius
Hon in question is known. Any two sewers having the same
■lean radius and constructed on the same slope, will have the
'Ocity» but not necessarily the same discharge, owing to the
[ the are4i of the sections,

l>w the hydraulic mean radius of a special section, as, for

ibolic section, we can find the corresponding velocity from

circular conduits for any specified sloiye; and from the

! velocity thus obtained times the area of the paraliolic sec-

sponding discliarge of that section can be computed.

siderable work is to be done with one type of sower of differ-

be found a great convenience to construct a diagram for

I save computations. A diagram of this kind is shown in

[iring tht^ discharge of semi-elliptical sewers, Gregor>'*s

g 3/4 full depth, by Kutter's formula for n = 0.015,

was furnished by John H. Gregor>^ and was published in

I News f March 12, 1914, from which the following paragraphs

rify fn nnr! eorresponding discharge of semi-elliptical flev%'er8

u running three-quiirtcrs full fJepth, can be readily

• rn. The diagram is based on Kutter'n furuiulu,

i>l5, and covers the nmge in diainetenj and velocities ordinarily

ijirutw'o. The diagram is practically self-explanatory but it

rii any point inside the diagonal lintsa the correspond-

Ycjutiiy, slope and discharge can be read.

404

AMERICAN SEWERAGE PRACTICE

''It is often desirable to know the velocity head and tiie loss of head at
entrance, or the sum of the two, and either or all of these quaiiLitttti eaa
be obtained from the diagram. Thus, tx> find the head nsquired U> prtv
duce a velocity of 3 ft, per second it is only necessary to find the iiiierw?-
tion of the velocity line 3 with the dotted line marked V^/2g imd r«d
the velocity head corresponding thereto on the scale markiid *Slopf ia
Feet per 1000/ or 0.14 ft. The loss of head at entrance would he r»»uad
by dividing the velocity head by 2, assuniinK that the Unas of hrad *it en-
trance would be 0,5r'/2^. Ttie sum of the? velocity head [Awn the kvm t<f
head at entrance is found in the tumie maimer as the velocity h*twA. ahjoe,
except that the dotted line marked L5 v^/2g is if) bo used in finding lh«
^intersection with the velocity line. For a velocity nf .1 ft ucr si-tvin.l ih^
raJue of 1.5i»V2^ ia seen to be 0,21 ft/*

Data of this character tao also be arranged iu t he form tif a Ulile,
Bimikr to Table 120, which gives the values of the hydraulic olemcntnof
the Boston t>'pe of horse-shoe section, aa computed by F. A. Lovejojr
of the Boston Sewer Department. These values are based on TC '
formula for n — 0.013* The BoBton tj'pe of liorse-ahoe »or
&hown in Fig. 132c. The values in the table multiplied by \/«, ^f = ifap
filope), will give the corresponding discharge of the sewer flowi"'' f"'l
The form of this table is that given by P. J. Flymi, ** Hydraulic J
Van Nostrand Science Series.

Equivalent Sectioiis. — A diagram designed by Frank Allen an 1 ^ i
F, Clapp, for use in the City Engineer's office at Providence, R. l.> miS
published in Eng, Record, Oct. S, 1904* This diagram, Fig. 147 show*
the dimem^ions of equivalent horse-shoe and circular conduits fl<wr«
ing full, ba,scd on Kutter's formula for n = 0.013. The farm
of the horse-shoe section is shown in the figure, // being tlio >t!flic»l
diameter, W the horizontal diameter; the radius of the side walla, tWt
and the radius of the invert 2 If. By equivalent conduits is meimt wtt*
duits having equal carr>^ing capacities but not neceasarily equal area**
In this type of horse-shoe section, the arch is always senii-circular. Th*
limiting cases covered by this diagram are a section having only arrh un»'
invert, in which H is 0.5635 W and a section in which H ^ Wn

The following modified form of Kutter's formula givoQ is t*wTia ^
Horton's ** HjTadulic Diagrams'' was used in computing thisdiagElD*

V = I ~~^ ^ 1 Vrs

in which F ia the mean velocity of flow, H the hydraulic mean rtdiil^ |

S the slope, and x and Z are coefficients. The (^n ' " ^'^\

but Mightly between wide limit* in the value of S, ^\

considered approximately constant witliin such limita. With " ' .
0.013 for 5 between the limits of 0,001 and 0.010. z - 0 ^^^i ^r^lt

i

THE DESIGN OF MASONRY SEWEBS

V

LB 129.-

— Valites of Hydraulic Elements of Horse-bhoe Sewek ^H

(BosTOX TrpE, Fici.

I32c). Computed by F, A, Lovejot of ^^|

Boston Sewer Dbpt. by Kittter

's FaHMtJLA, n -

0.013

■

fa.

Aratt — A

Hydraulic

mean ndiui

B in ft*

Wetted pcnmetur
in ft.

For diiH'hftrKe,

AoVU
en. It p«r eec.

1

0

7,463706

0-7615

9.800487

719.3024

U

7.86707

0.7818

10.06183

773.2628

^^M

■ <

•8,38365

0.8046

10.35684

835-7266

^^M

■

8,75948

0.8250

10.617195

893.5074

^^B

■

9.19592

0.8453

10.87854

953,5299

1

5

9,66982

0,8654

11.172556 '

1019 5322

fl

6

10.15892

0..'i884

11.433902

1092.2659

^^1

hJ

10.63162

0.9000

11.69514

1158.9166

^^1

H

11.17067

0.9325

11.989229

1239.8739

1

K

, 11/65995

0,9517

12,250609

1311,9132

1

■

" 12.16593

0.9731

12.491844

1380,7469

J

■

12 74634

0.9952

12.800934

1479.1253

^H

m

n

1.{X)7

13.0672

1559.3082

^H

1

i:v

1.0434

13.32854

1653.6076

^H

2

14.4215

1,0586

13.6225

1746.5319

H

h

14.9771

1.0787

13,8849

1834.4428

^

W

15.54937

1.0992

14 1452

1930,9992

1

8

16.20452

1 . 1222

14,4392

2040.3911

1

6

16 7(m2

1 1424

14.7006

2131,3518

^j

7

17.39871

1.1628

14.9019

2243,1929

H

8

18.08703

1 . 1855

15,25595

2361 4387

H

9

18.02607

1 2003

15,517300

2453.575

^H

v|0

19 34756

1.2202

15.77704

2585-1100

^^1

^H

20 07735

1.2491

16,07265

2715-7890

^^1

B

20 7325

1,2693

16,33400

2834,0581

^1

H

21 4042

1.2S97

16.5953

2959.277!

H

^H

22 16718

1 3125

16.8893

3101 5844

^^1

^H

22 sruyO

1.3326

17,1507

3228 2596

^^1

^H

23 r»(K)4

1 3531

17 4120

3362,0143

^^1

H

24.3648

1,3760

17.706

3518,0714

H

H

25.0863

1.3962

17.9674

3655.9182

H

^B

25 8244

1.4166

18.2287

3801.3702

^H

^H

26 6619

1.4393

18 5227

3963.9995

^^M

^H

27 417r.

1.4596

18 7841

4116 7K21 1

^^^

1

2H.1H79

1 480

19 0454

4270 7136

^^1

L

■•

J

406

AMERICAN SEWERAGE PRACTICE

Tabue 12Q.— Continue.

Diam
ix
ft.

5

etcr
1
in.

Area - A
in aq. ft

Hydrmulie

meanrmdiiM

R in ft.

in ft.

For diacharie.

AcVr
m. It. per tee-

11

29.0679

1.5030

19.33M

4447. 322S

6

0

29.8548

1.5231

19.6008

4612.3474

6

1

30.655

1.5434

19.8621

4774.4581

6

2

31.5631

1.5664

; 20.1561

4951.4739 1

6

3

32.3924

1.5865

1 20.4175

5138.4725 \

6

4

33.2310

1.6070

' 20.6788

5313.4840 1

6

5

34.1837

1.6299

; 20.9728

5517.6147

6

6

35.0379

1.6500

21.2342

5699.9172

6

7

35.908

1.6705

21,495

5879.082

6

8

36.8955

1.6932

21.7895

1

6105.650

6

9

37.7829

1.7133

22.0509

6301.0709

6

10

38.6868

1.7340

1 22.31019

6501.3060

6

11

39.7151

1-7568

! 22 6062

6730.3951

7

0

40.6357

1.7770

j 22.8676

0944.2581

7

1

41.5728

1.7975

1 23.1289

7158.2220

7

2

42.6343

1.8201

' 23.4229

74O2.O06S

7

3

43.5880

1.8404

23.6843

7621.617

7

4

44.4738

1,8573

! 23 9456

7846.149

7

5

45.6562

1.8836

24.2396

8099.739

7

6

46.6481

1.9039

24.5010

8330.442

7

t

47 6482

1.9257

24 7623

8576.752

7

8

48 7794

1.9472

25.0563

8837.631

«

9

49 8098

1.9674

25 3177

9078.188

7

10

50.8443

1.9876

•25 58S8

9334.582

7

11

52.0186

2.0107

•25.8730

9619.087

8

0

53 0752

2 0311

26 1344

9892.649

8

3

56.4438

2 0943

26 9511

107-23.857

8

6

59 9169

2 1576

27 7678

11601.485

S

9

63 4912

2 -2214

28 5845

12534.523

9

0

67 1733

2 2M8

29 4012

13534. 52S

9

3

70 9.V49

2 3487

30 2179

14499.966

9

6

74.VI43

2 4119

31 au6

15552.709 /

9

9

7s S332

2 47ol

31 s,M3

16665.544 /

10

0

82 9300

2 ,VW1

;^2 668

17796 910 /

10

3

87 1*262

2 ^021

3;^ 4<47

19027 035_J

THE DESIGN OF MASONRY SBWERS

407

Arw - A
in Ml, ft.

Hydraulic
R in f*.

Wwttcil Peri meter
in ft.

For discharge

Aci/R
cu. ft. per sec

10

5

91 4303

2 6655

34,3014

20248 307

10

0

95.8339

2.7294

35,1181

21561.979

11

0

100.3453 1

2 7927

35/9348

22903 471

11

3

104.9.562

2.S559

36.7515

24266,969

n

6

109.6749

2.9199

37.5682

25718,536

1

9

114,4931

2.9831

38.3849

27226.626

l2

0

110 4192

3.(He4

39.2016

28757.289 '

2

3

124 4468

3.1103

40.0183

30386.664

1

fl

129.5781

3.1736

40,8350

32032 044

12

9

134 8110

3-2367

41.6517

33716 085

13

0

140 1517

3.3007

42.4684

35479 457

Table 12Q.—Co7Uinii€d,

181.69, with sufficiently clone approximation; while for 5 between
10 and 1.00, x = 0.542 and Z = 181.02.

order to describe the metliod of using the diagram in Fig. 147 the
owing example is quoted from Eng. Record, Oct, 8, 1904:

lti?quircd a horse-shoe shape 78 in. high^ equivalent in discharging ca-
ity when flowing fuH to a 96-in. circular section. Find 78 at the left and
^t the bottom of the diagram; trace the horiKorttal line through 78
la Intersection with the vertical through 96, which ffills upon a height
fonul numbered 65; then trace along the 78 horizontal again, to the
It or left, as the case may require, until the 05 width diagonal is met;
J IcMik to the top and find 120 for the width of the horse-Hhoe. All
cnftions are given in inches. A 78 X 120-in. section of the height shown
Quivalent in flowing capacity to a 96-in, circle."
W flections larger than those plotted on the diagram a convenient
Winn, such iws one-third, of the dimensions may be taken, and the
lilts increased three times to obtain the desired figures*

SELECTION OF CROSS-SECTIONS

fidectitig the dimensions of the masonry section to provide sufll-
]«•!*« to prevent excessive stresses in the masonry and at the
u '•• cjconomical of material, it is unwise to reduce the thickness

IheoretJcaJ limits on account of the uncertainty as to the quality of
rk ohtjiinalde. The relative saving by using extremely thin sections
h liigh »tre?wei4 m small and is usually false economy. For majsonry
er» 5 ft . in diameter and less the thickness of the best section will often
l*ml more on the minimum thickness allowable on account of con-
totiun methods than on the stresses developed in the section. For
&tid reinforced concrete sewera, a mioimum crown thickness of 5 in.

408 AMEBIC AX SEWERAGE PRACTICE

id con:«idered good practice but a thickziesB lew than that amount is man
or less quesitionable. when the intention is to obtain firstHslass work.

Enqnikai Foamilas for Thicknes of Arches. — ^In sdecting thedimen
flions of a trial arch section, some of the following formulas may be of
aasistance. They should not be relied upon, however, to gjve the final
section. The formulas are only approximate and do not take into
account many of the conditions which should govern the design of an
arch. The majority were developed for use in designing arches having
spans of 20 ft. or more and on that account may be leas accurate for
arches of eimaller span.
In the following notation all dimensions are in feet.

te =* thickness of arch at crown.

ts = thickness of arch at springing line.

5 = clear span of arch.

R = rise of intradoa

r = radius of intrados at particular point under consideration.

F = height of earth fill over crown of extrados.

F, F. Weld in Eng. Record, Nov. 4, 1905, gives the following:

''The writer has devised the following equation, based upon a study of
all available data upon the subject and his own experience in designing arcfaa
for a great variety of conditions. He believes it a safe guide for all 0Fdinai7
conditions of span and load:

tc = 1^2 (V^' + O.LS 4- O.OOoLx -h 0.002oi>)

where Li = live load uniformly dLstributed, and D = weight of earth fill
over the crown, both in pounds per square foot. **The arch ring at the
quarter points sliould have a depth of from 1{ ^ to IJ /e, depending
upon the curve of the intrados."

W. B. Fuller has developed the following rule for unreinforced con-
crete used where sheeting is not required: Make crown thickness a
minimum of 4 in., and then 1 in. thicker than diameter of sewer in
feet. Make thickness of invert same as crown plus 1 in., but never
less than 5 in. Make thickness at springing line 2} times thickness of
crown, but never loss than 6 in. If ground is soft or trench is unusally
deep, these thicknesses must be increased according to experienced
judgment. (Taylor and Thompson, 'X'oncrete, Plain and Rein-
forced,^' 1009, p. (384).

Taylor and Thompfioriy in *' Concrete, Plain and Reinforced," p. 541,
state that tiie Weld formula gives fairly correct results in ordinary' cases.

"Obviously the thickness for a hingelcss arch sliould increase from the
crown to the springing. The radial thickness of the ring at any section is
frequently made eciual to the thickness at the crown nuiltiplied by the secant
of the angle whicli the radial section makes with the vertical. For a three-
centcHMl intrados and an extrados formed by the arc of a circle, these

■ TUB DESIGJV OF MASnXRY SEWERS

^^1

A

^1

V

-f\-

^^B

^^1

^1^ -

^1

. ^4-—^a ^

^1

:3!r3iK 4

-.% ^ ■

^^eXj -

^ ^- I

5^s

I

x^ /

ji

jS^Sl [

--,iii

% B ^1

KSj^s,

.^Ip

- 1 ■

SvVCwS.

-^4^

wMw-

'S ^H

^^^^ ^

^j

w///

»? 8 ■

^^m

Wm -

oil ■

^^^^m

Ay// J

W -

^ §^iw

/:

^ /y/j J

Vl -

o V ^H

l^^v.

-;.

\

^^

yy////

^

_ il ■

^

o/w

f

o '3 S ^^H

k//

w6

^s 1 .^H

^y

z

0//

8 S ^^^H

Zpi

K ^

///

. < .. ]

^ 1 _g ^1

: T^Z^A

^

r^

^■5 1^ H

%L

p^ ^ cJ ^H

: /zziil

^

w^

SI 1 I

. /ZZZz//

/

^m~

.ZZ/Vy%$

V;

■

i//xy-/j L

//

>^

^H

IjCc/Ai//

/

^

o S) ^^^™'

t^^A/ul/L

/

^

$ ^ ^g

lyjo/tjj

~o '? ■

ijYJ^^tr

/T-jiftt

s

^^1

^^1

*.iym%^

1

^s.

■

ftJilf^

^^.

^ ^^H

^^H

^^^^^B

tizri^

^

/iiJ^i

^. ^1

410

AMEUICAN SEWERAGE PRACTICE

trial curvesmaybeatthe quarter points a distance apart of l^tol} tti
the crown thickness and at the apringings 2 to 3 times the crown thickni
Baker's ^* Masonrif,*' t^uth edition, p. 643, givea a number of diffi
t^mpirieal formulas for determining tlie sections of a masonry arch, frona
which the following arc quoted:

** TraiUwiTie's Formida for the depth of the keystone for a first-dAas ou^^-
fltone arch, whether eireular or elliptical, in

tf - iy/ir + iS) + 0,2
For seeond-cla^ work^ this depth may he increased about one-eighth par^;
and for brick work or fair rubble, about one-third.

*^Rankijie*H Formula, for the depth of keystone for a single arch is
U = y/0.V2r
and for tunnel arches, where the ground is of the firmest and safest »

ic = ^m^2RyS)

and for soft and slipping materials twice the above. The segmental oreh^^l^
of the Kennies anvt the 8iephensonB» winch are generally regarded aa modi^^fci
have a thickness at the crown of from 1/30 to 1/33 of the spim, or of fn.^^
1/26 to 1/30 of the ra*lius of the intrados,

'* Dejardin's FormulaUf which are frequently employed by French engimect^i**!
are as follows:

For circular arches,

if R/S « 1/2, (c - 1 + O.lOOr

if R/S = 1/6, tr = 1 + 0.06«>r

For elliptical and basket-handle arches,

if R/S - 1/3, r^ - 1 + 0,070r

By Dejardin's formulas the thickness at the crown decreaaus a^ uu- n
increases^ — ^as it should*

" CroizeUe'DesnoyefMf a French authority, recommends the followli
f oruiulaa ;

if R/S > 1/6. /c = 0.50 + 0,28 vYr

if R/S - 1/6, e, = 0.50 + 0 26v'2r

American Civil Efiginters* Pockttbook^ first edition, p. 023^, givea ll^^
following formulas for the approximate thickness of a masonry arch
the crown for spana under 20 ft. :

^, = 0 04(6 + .5)
U = 0 06(6 -f 5)
U = 0 04(6 + 5)
U - 0 03(6 + ,5)

First class aahlar
Second class ashlar or brick
Pliiin concrete
Reinforced concrete

The thickneas of masonry at the springing line may W computed i
the following manner from the crown tliicknca^, aa given by the abov*
formulas*

''Add 50 per cent, for circular, parabolic and catenarian archca haf4n|(i
ratio of rise to span h^8« than 1/4. Add 100 per cc»nt. for circidar* panvboli

Add 150 percent, for elliptical, five-centered and seven-<^iitored
These thickiiciidos should be xneasured along radial joints.'*

It b also stated that the crown thicknesses, computed by the above

r»rmubL«ry should be iQcreased about t>0 per cetit. for culverts under a

Li^fj lill and al^out 25 per cent, for railroad arches.

Fryf, in his **Civil Engineers' Pocketbook/* 1913, p. 760, states that

ic following formulas give very close results for first-clasa concrete and

it-jftone work;

For highway bridges, i, = \ 0,01^'(|' + a) + 0. 15

'- = \/o.01s(|-+4) + 0 20

For high highway embankments
or for railroad bridges,

h= yjoQisi^^ + 5) +

0.25

For high railroad embankments,

For all cases f, = Ul + 0. 002(S + 2/2)J

BnUhrin Latham, in his ** Sanitary Engineering/* second edition, offers
*e fullov^ing formula as being convenient for determining the proper
ickueAs of the brickwork of sewers: '^Thickness of brickwork in feet =»
01'// wlif'tp tl = (k'pth of excavation azid r = external radius of

UfiLHun^ m liijJi ••>«_' wersige Systems," p. SO, gives Depuis' formula as
i-ing ic use in France for computing the thickness of brickwork for

Krif w'wen^ under aide walks, this is

t, = t, = 02VS
J^or sewers under carriage ways, this is

t, = L = 0,2\/^ + a02F
JkuierdafU, in his "Reinforced Concrete Arches/' 1908^ p. 43, pre-
*CTibt« two fonnulas for proportioning arches. The first, the Weld for-
^\i\a, has already been given, and the secojjd, the I>, 13. Luten formula,
»« ttjfoUuws:

3,S'(/?4-3f*) . LiS^ . L^(S + 5R) ^

i, =

H-

4000/^ - 5* ^ 30,000/2 ^ 150/it ^ 4
I F * the depth of fill over the crown of the extrados, in feet*
' L| « Live load uniform in poimd per square foot.
Lm— Moving load that wiU !>e concentrated on single track
or single roadway over entire span in tons of 2000 lb,
^id nm, In their ** Reinforced Concrete.*' 1904, p. 104, suggest
^ foHoviriiig: ^Wx\ approximate depth of the ring at the crown for
'milofced-cuncretc arche-s may be found by the formula,
/. - 0.0075(*S + IQHY'

412 AMERICAN SEWERAGE PRACTICE

Howe, in his "Symmetrical Masomy Arches," first edition, p. 44,
gives among other formulas, the majority of which have already been
quoted, the following, designated as Perronet's formula for circular or
elliptical arches (taken from paper by E. Sherman Gould, Van No»-
trand's Mag., vol. xxix, p. 450.)

tc= 1 + 0.0Z5S

Parmley. — The following empirical formula was derived by Walter
C. Parmley from a number of analyses of the stresses in sewer archo
made in connection with the design of the Walworth sewer, Clevelaod,
Ohio (Trans. Am. Soc. C. E., vol. Iv, p. 357). Let t, = the required
thickness of the arch on a horizontal line through the center of the eewer,
in feet, and S = the span or diameter of the sewer; then

S

t.=

^ 4- 2.572

This formula is applicable to arches constructed of brick masonry.
Emile Low, in Engineering News, June 15, 1905, offers the following
formula for the crown thickness of masonry arches:

He states that the formula with a divisor of 6 instead of 8, as given, vil^
closely approximate the crown depth of many modern structures.

One method of computing the thickness of the arch at the springing
line has already been referred tp in the paragraph quoted from Taylor
and Thompson. This method assumes that the loads are vertical and
that the horizontal component of the compression on the arch ring »
constant.

Another formula for the thickness of the arch at the springing line or
the thickness of the abutment at the springing line is that given by
Trautwine, as follows:

t. = 0.2r -\-0.1R + 2.0

The formulas mentioned in the preceding paragraphs are based for
the most part on existing structures, and on that account the useof thf*
formulas may lead to safe results, for similar materials and conditions
of load, although the factor of safety will be in doubt.

CHAPTER XII

; OF SEWER SECTIONS AND THE LOADS ON SEWERS

Sections Actually Used- — The designing engineer will derive
rice from a s^tudy of sewer sections used by other engineera*
ona of many such sectiona are available^ although ao scat-
Jii engineering literature as to make difficult a ready corapari-
Jialicnt features,

rhere considerable aewer construction ta in progress, it has

lound advantageous to formulate a set of standard sections

I cliflFerent sizes, thus making it unnecessary to prepare special

I sewer. Thc^e standard sections, especially the smaller

bh based lai^el}^ on the analysis of a number of sections

adopted, and upon experience in their construction. They

therefore, as representing the /udgraent and experience of

I reepect to sewers actually constructed, and as not neces-

fconfined to theoretical lines.

irclating to and the illuatrationa of sewer sections presented
: pages, should be considered
liahing to the designing engi-
ions which he may fjnd helpful
f df signs for the particular work
I the local conditions attending
ion of these sewers cannot he
It ahould not l>e as-
' of them can be adopted
Ication for the conditions sur-
f work in hand.
Lrd Sewer Sections. — In Figs* 148
sive, and in Tables 130 to 134
} number of sections adopted as
I several cities,

Ky.— The cross-sections of

ftewers shown in Fig. 148,

130, were prepared for the Conimisnioncrs of Scw-

llisviUe, Ky.| J. B. F, Breed, Chief Eng. The dimensions

i on what cxpenence had shown to be a safe thickness of

' the conditions there existing. The minimum Ihicknens

^ wid at tlvo invert was ftxed at 5 in. because of the practical

413

ti

Via. 14S, — ^Ltjuisville
standard concroto sectinn.

414

AMERICAN SEWERAGE PRACTICE

Table 130. — Dimensions of Plain Circular Concrbtb Sewers,
Louisville.

Qiuuititirof

DimeoBioaa of the Bcctions

COIMRto

ea. yvLpcr

Diam-

1 ^i

lin.ft.MVfr

//> Bi

Br

A^i

Kt

1
Ri 1 At

As

Finn 1 Soft

eter

1

24*

5'

5M' 7J'

V sr i 6'

nor

I'D'

I' 6'

V 5'

0.13 O.IS

27'

5'

5', I' 91'

nor

01'

r lA'

I' ir

1' 8'

rer

0.15 O.IS

30'

5'

5'|2' 0'

2' U'

71'

r 4r

I'S'

1' 10'

I'S-'

0.18 0.21

33'

5'

5'i2' 21'

2' 4J'

81'

2'6H'

I' 41'

r 0'

i'«r

0.19 1 o.a

36'

5'

5'

2' 4r

2' 61'

9 '

2' 91 '

1'6'

2'2 "

I'll'

0.22

o.»

39'

5'

5'

2' 7r

2' 91'

91'

3'OA'

i'7r

2' 4"

2-01'

0.25

0.29

42'

6'

6'

2^ 91'

3' 0 '

lOJ'

3' 3| '

I' 9'

2' 6'

2' 3'

0.20

0.35

45'

6'

6'

3' 0'

3' 2J'

Hi'

3'6A'

noi'

r 8'

2' 41'

0.33

0.40

48'

6'

6' 3' 21'

3' 6J'

1' 0'

3' 9'

2'0-'

2'10''

2' 6'

0.38

on

51'

6'

6' 3' 4|'

3' 8 '

I' or

3'llH'

2' ir

3' 0-'

2^71'

0.41

O.tf

54'

6'

6',3' 7J'

3'lOr

1' ir

4' 2r

2' 3"

3' 2'

2'9'

0.43

0.S3

57'

6'

6' 3' 91'

4' ir

I' 2r

4'5A'

r 4r

3' 4'

2'10|'

0.47

0.57

60'

6'

7'|4' 0"

4' 4 '

I' 3'

4' 81 '

2' 6'

3' 6'

3'0'

0.53

O.fS

63'

6'

7' 4' 21'

4'6r

1' 3r

4'llA'

2' 7r

3' 8-^

3' U'

0.57

o.n

66'

6'

7';4' 4}'

4' 9J'

i'4r

5'ir

2' 9'

3' 10*'

ys'

0.61

0.77

69'

«'l

8' 4' 71'

5' 0 '

1' 5r

5'4H'

2'ior

4' 0'

3' 41'

0.66

O.M

72'

6-1

8'l4' 9r

5' 21" 1' 6'

5' 7r

3'0'

4' 2'

3' 6'

0.70 O.MJ

difficulty of obtaining with certainty a first-class wall of monolithic con-
crete of less thickness. The shape of the masonry invert is depe deot
upon the character 6f the excavation, whcthcrit is in firm ground orwft
ground, these being the terms applied to materials which would id
would not stand when trimmed to the shape of the firm ground section.

Circular Sewer. Egg-Shaped Sewer.

Fid. 140.— Stiiiuliird plain concrete sections. (Bronx.)

For sewers of this type constructed on timber platforms or piles theUD^
of the under side of tlu^ concrete invert should be horizontal. For reio*
fon^ed-concrete sections, tlie thickness of masonry shown for the \asp^
diani(?t(Ts may be somewhat reduced, according to J. H. KhrM

EXAMPLES OF SEWER SECTIONS

415

dgning Engineer, Commissioners of Sewerage of Louisville,

Qm the authors are indebted for valuable assistance.

fitf the Bronx, — Fig, 149 shows the standard forms of circular

iped sewers, constructed of unreinforced concrete, published

Details of ConvStruction/' 1913, Borough of the Bronx,

rd H, Gillej^pie, Chief Eng. of Sewers and Highways.

\xm thickness of masonry, as given in these tables, is 6 in, for

diameter of 33 in.

-Standard Plain Concrktb Sections^Borough op the Beonx^
New York City

Crown

e'^

8"

Width of

bftM

5' 3"
5' 6".
6' 3"
6' 6"

7' n"

OuUide rsdtu9
&

Uffwfc

B

2' IJ"
2' 3"

2' 71"
2' 9

2' lOV
3' 0"

71

71"

7ft"

7A"
71"

7A"

1' 9H"
V lift"
2' OJ"

2' ir

2' 31"
2M|"

Cobcrtfto

11,94
12,82
16.41
17,46

18.52
19 60

^

Oown

WidlU
of b«M

rudiua

r

Offwt

oreta
are*
•g.ft

.1

£

■

6"

i'9"

I'lli*

2' 101"

71"

5ft"

2' 31"

12.82

p

e"

S'O"

2' I"

3' Oft"

74"

5ft"

2' 5 J"

14. OC

«"

B"

5 3"

2' 2"

3' 2"

9"

6"

2' 6H"

14.75

50"

8"

6' 0"

2' 7"

3' 2ft"

9"

5ft"

2' 8ft'' 19. Oi*

Si"

8"

6' 3"

2' 8"

3' 4H"

9"

6"

2' 10ft' 20 32

66"

8"

6' 6"

2' 9"

3' 91"

12"

6t"

3'Or' 21415

lory's Semi -elliptical Section. — The etandard Ben ii-eUipt teal
fwn in Fig, 150, was worked out in 1910 by John IL Gregory in
[with the preparation of plans for a large trunk sewerage pro-
fit tills section, wliich was designed to be built of
lapted for sewers 6 ft. and over in diameter than for
The several dimensions are given in terms of the diameter,
Eictioud of the diameter were so chosen, starting with any
in feet that with increments of 3 in. in the diameter, the
aensiona will come out in whole inche«j or inches and fractions
common use, as for example, quarters, eighths or six-
Mr. Gregory further stated that the section is suitable for use
! conditions are such that the aide walb will be firmly sup-
^e sides of the trench. Where these conditions cannot be
be side-w.'dl sections should be modified to meet the conditions.
Bontal and vcrti<;al diameters of the section arc the n&me and
tttl dianieter is located one-third the length of the vertical
[JVC the bott-om of the sewer. The gross area of tliis section

mm

^^1

416

AMERICAN SEWERAGE PRACTICE

on outside lines equals 1.265LD^ the area of the section inside
0.8176D* and the net area of masonry = 0.4475D*.

Table 132 shows the area of these sections and the net volume •
masonr>- in cubic yards per linear foot for each size from 6 to 13 ft. 6 ii

Fig. 150. — Gregory's standard semi-elliptical section.
Tvm.K 132. — Area and Volume of Masonry in Semi-elliptical Se^'EBS

Gregory's Section (Fi«. 150)

Gro.«4S area on

outuide linea

1 . 2«5Z>«

(2) _

45.54

Area in square fe

Area of section

inside

0.8176D«

(3)

29.43

et

Volume of masonr)
in cubic yawl*
per linear foot
0.01657Z)'

(0)

lii-iido iliitmotcr

of nrwor

I)

vl)

Net area of

masonry

0.4475D«

(4)

iV 0"

16.11

0.597

iV 6"

53.45

34.54

18.91

0.700

7' 0"

61.99

40.06

21.93

0.812

7' iV

71.16

45.99

25.17

0.932

S' 0"

80.97

52.33

28.64

1.061

S' 0"

91.40

59.07

32.33

1.197

9' 0"

102.5

66.23

36.25

1.342

W 0"

114.2

73.79

40.39

1.496

ID' 0"

126.5

81.76

44.75

1.657

10' 0"

139.5 .

90.14

49.34

1.827

ir 0"

153.1

98.93

54.15

2.005

ir t>"

167.3

108. 1

59.18

2.192

V2' 0"

182. 2

117.7

64.44

2.387

V2' (>"

197.7

127.7

69.92

2.590

i;r D"

213.8

138.1

75.63

2.801

i.r (>"

230.6

149.0

81.56

3.021 _J

EXAMPLES OF SEW EH SECTIONS

41:

• by 6-in* steps. Additional data in regard to tho hydraulic

nUot this section are given in Table 128, Fig. 141, and the velocity

and dMcharge for various diameters are shown in PMr, 146. Mr.

[jfei:ory further stated in Engineering News, March 12, 1914:

*in tsmchision it ahouid be pointed out that the dinH^nnions given for

Plhf mfL^nTTry »eotion are a minimum and that not only would the best of

'id workmanship be required , but also cnreful inepeetion. Where

it ions cannot be obtained or where the sewers would be required

FlQ. 151. — Authors* standard semi-etlipticaJ section.

' carrj" heavy loads, the sections should he reinforced with steel or the

*i'tn<»HHion3 increnseil, e.speiMally the arch and side walls/*

Aotfaors' Semi-elliptical Section. — The details of the semi-elliptical

ctioii«hown in Fig. 151 and Table 133 were developed by the authors

I the experience in constructing sewers of this tj^pe at Louisville, Ky.

^ all of the principal types, the stresses were carefully analyzed but

Ktandards were developed in the Louisville work and on that

he sections actually constructed vary slightly from the section

^nwa. This sewer is intended to be constructed of concrete reinforced

' ^ '' ^ ' ' , Under favorable conditions the thicknesses of masonry

-lightly nduced while on the other hand for conditions of

I iuacimj^ it may be desirable to increase them somewhat. For aver-

litioiLHt, however^ the section shown ta believed to be conser\'ative.

418

AMSRWAy SEWERAGE PRACTtCS

Tabus 133, — Dockksioks of Arrrsoia* Smui-ixiAmcAi* Sswn Btacnm

tScc Fi«. 151)

4

Thirkn

rof

lotrrior tm&Sa

vertical

ai-
rt In

\rv^ I Hjr-

>C«iifecr!Crown

9li| ft-

nuiiiM

Crowm'

(t, I It. in.

' of in-
vert
and
«9»ring

UXMS I

ft. ia. '

nnd

«d«

wmll

ft. in.

Side

intra-
doa

Exterior rsdii

Invc^rt I

aad Crcifml
aide ertrar- '

extra-: doa I
doa I

Inrotl

Aiaa

ft. ia. I ft. in. I ft in. 1 ft. \n

Q«1
«tr

6 0

a 0

7 C)

7 fl

8 0
8 0

0 0

in n

10 0

n 0

11 6

la 0

12 »

13 0

13 «l

14 0

28,3

38.4

44.05

«0,1

«3.4
70 7
78.3
7D.3

«4.75
103.5
112 75,
122 4
132 4
142 7
153 ft

1.442 0 0

0 9

2 0

0 8

7 6

2 0

sa

i.5«2! oej

Oftt

2 2

8©|

8 11

2 81

8 111

1 ft83* U 7

0 101

24

7 31

8 «

2 11

«7|

1.803, 0 7*

0 III

20

7 01

Oil

a u

10 31

I 023 0 8

1 0

2 8

8 4

10 0

3k 4

110

2 043 0 81

1 Of

2 10

8 101

10 71

3 01

llSi '

2.103 0 9

1 U

30

• 41

11 3

3 fk

t3t4*

2-284 0 Di

I 2\

3 2

0 10|

11 101

3 111

13 H

2 404 0 10

1 3

3 4

10 5

12 0

4 2

13 D

2 525; 0 101

I 3!

3 6

10 Hi

13 1|

4 41

14 H

2 64fl| 0 U

1 41

3 a

11 61

13 0

4 7

15 11

2 7Wl 0 Hi

1 64

3 10

H lU

14 41

4 01

15 Of

2.884J 1 0

1 6

4 0

12 6

15 0

5 0

10 0

3,005 I 01 1

1 61

4 2

13 Oi

15 71

6 21

17 2i

3.125 1 1

1 71

4 4

13 01

10 3

55

17 101

3.245 1 11

1 81

4 0

14 Oi

10 101

5 71

18 0|

3 365 12

1 9

4 8

14 7

17 fl

n nv

Itt 3

aq f»

14. I.

Jf5.. t'
2!t r

01 .11

m ,1

Aral ol wiitorwiiy « 0.7831/)^, Area of concrete section «« 0,3924I>«.

St Louis Fiye-centered Arcli. — ^The standard eross-«ection ui ttj«* u
coiitered arch or somi-cUiptical type of ecwer shown iu Fig, 152 «1l|
furruHhed by W. W. Homer, Principal Asst. Eng., St, Louis Sci
Oojinrtmciit. Table 134 gives the leading diraensions and In'^fti
proportios of this aection. The following notes in regard to the
ijf thi« i<tandard section have been taken from a paper by F. J*
m;iivri. Ofhce Eng., St. Louis Sewer Department.

In the preliminary studies^ three s>^t€m8 of external h
Mtuditul. The first, called the ** standard*' system, was com
vortical forces due to the total weight of the backfill resting on the
urrh and a mnall amount of horizontal earth pressure, d^i
amount upon the angle of repose of the earth, assumed tt>
Th** HtH'ond system of external forcci* consL^tad of vertical forcen only,
ignored the existence of any horizontal earth pressure. This case Wi
expTotis the condition of the angle of repose approaching IM) dej!.,
would cover the possible cas<? of horizontal forres in tlic '
Hyntem of loading having been assumed too jf^eat as coujpari
vortical forces. The third system consisted of external fonitj*
normal to the center line of the arch, these forces being assumed eqvwl
the weight of the fill, which is equivalent to a very wet conditioo
hydrostatic pressure- In eaoh case analyses were made for

EXAMPLES OF SEWER SECTIOffS

419

Ho If Section in Rock, j Hqlf Section In Earth.

Fig. 152. — St. Louis five-centered arch sewer,

I - 0.4(H8J/: Rt - 0.5286//; Rt - n 7774//; Ra - 2,73216 - 0,845g(« + 6); A» -

OU ^ 6>; fi. - 1.8S62(a ^ b) - 2 732U; B - 0.1222// - 0.16«»7: D - 0.7580J^

L6521; Al«# * 0.5d09J/3 - 0.3854// - 0.1506; Wetted perimeter • 2,8211H-

Pablu 134*-^PROPERTra3 OF Frv'E-cuNTSiiED Arch Sewer (Fig. 152)

, Wf-ttH

Hyd.

"

Ri

/?■

Ri

B

D

Area

p«rini.

rwL

ft

ft. in.

ft. in.

ft. in.

ft, in.

ft. in.

■q. ft.

ft.

ft.

6

~2^5i

3 2ft

4 8

0 m

4 0

17,729

16,103

1,101

7

2 10

3 81

5 5ft

0 8i

4 9i

24,635

18,924

[ 1,302

8

3 2}

4 2*

6 21

0 9i

5 6ft

32,064

21,745

1.502

j»

a 7i

4 9ft

0 111*

0 lift

0 3ft

41,813

24,566

1,702

10

4 OA

5 8ft

7 9ft

1 Ofi

7 Oft

52,085

27,387

1,902

11

4 5A

5 91

8 Of

1 21

7 9i

63,479

30,208

2,101

12

4 lOA

6 41

9 3tt,

1 31

8 61

75,994

33,029

2,301

la

5 3i

0 10ft

10 u

1 5ft

9 3}

89,631

35,850

2,502

-i^

5 8

7 4H

10 lOf

1 6ft 10 Oil

104,390

38,671

1 2,699

bs

e 01

7 lU

11 7H

1 8 10 9H

120,271

41,492

2,899

f^

e 51

8 51

12 51

1 9ft 11 7

137.273

44,314

3,098

i^

(JiOA

8 im

13 2ft

1 10tt;i2 4t

155,397

47,135 ] 3,297

■is

7 3A

9 6ft

13 IIH

2 oi

13 U

174,644

49,956 3,496

10

r 8ft

10 0§

14 9t

2 11

13 lOft

195,011

52,777

3,695

■20

8 u

10 6i

15 6ft

2 3ft 14 7ft

216,501

55,599

3,894

B2

8 101

n 7ft

17 n

2 6i 16 li

262,845

61,240

4,292

K4

0 8A12 81

IS 7i

2 Oft 17 7}

313,678

66,883

4.690

Kg

10 6A

13 8fJ20 2ft

3 0| 19 2A; 368,996

72,525

5,088

KS

U 4

14 9J !21 9ft

3 3ft 20 8i

428,804

78,167

5,486

Bo

12 U

15 lOft'23 31

3 6 22 2\

493,098

8:3,810

5.884

420

AMERICAN SEWERAGE PRACTICE

depths of fill, 10 ft ., 20 ft., 30 ft. and 40 ft. from the ground surface to the
crown of the sewer.

The line of pressure in the arch for the standard system of forces was
found to be a close approximation to an elliptical curve, and as the forces
wexe assumed symmetrical, the major axis of this ellipse coincided with
the vertical axis of the arch.

The arches were actuaUy designed with a curvature following that
of the line of pressure of the standard system of forces. The line of pres-
8ur«i for the second system of forces fell inside the standard line, thereby
causing negative bending moments between the crown and springing
line in the arch. The line of pressure for the third system of forces, for
nearly all depths of fill, fell outside the standard line of pressure, causing
IHvitive Inrnding moments between the crown and springing line.

TaHUK UV5.— l^UNCIPAL DiBCENSIONS OF SeWERS CONSTRUCTED IN LOOB-

viLLB, Ky.; 1907-1913

hvt

Ml

11 ill.

3^

4

! 5

i 6

1 7

1 i » 1

ThickDces of caD«rrt«

offiU
(ft)

■i^itUl
ft. in.

Type of Kwer

II

a 0

At i(prizi^Ei#

Airh
(ineheii)

Side

(in.)

i:i 6

Horee-^hoe |

11

12

17

17

25

\lX U

14 :\

Horse-shoe

8

10

12!

I2i' lo

;i

i:i s

rt 0

Honse-shoe

10

12

15

ISl 30

>u

12 ^1

13 a

Horse-shoe

3

10

141

14 J 20

11

' 12 a

12 A

8cmi-el1iptical

9

9

14

14 25

ir*

^ \{\ 11

U\ 0

1 Scmi-elUptical

S

S

16

16 42

%^

* 10 U

10 7

Horae-shoe

10

U

U

17 1 37

M

W 0

12 0

Horae-shoc

8

s

17

17 lis

1 1» 0

u t»

Horae-shoe

S

s

IS

15 U

|i'-*

7i;

10 0

Horse-shoe

S

8

12

12 , 13

i^h**

1 sn

8 :i

Scvmi-elliptifal

s

S

12

12 1 12

•\"i

^ H 11

8 {}

S(*mi-elliptiral

9 '

7

15

15 ; I.U

. r 11

7 {}

Hcmi-cUiptipal

8

7

13

la , n

\s.

H ;i

0 3

So»ii-cUiptical

6

6

81

8;" 10

s

fi i\\

5 in

Hcirse-shoc

6

6

7i

7i

17

' 'i li

5 6

C?ircular

e)

6

10

10

n,

VA

4 n

r> 2

Horse-shoe

7

6

10

10

18

111

4 i\

4 a

BemiH>llipticiil

7

6

9

£»

2S

III

5 fi

n B

Cirouliir

ft

7

10

10

S

i\ :i

.1 3 CirnilaT

5

R

ft

H lOj

p.ii.i from Con tract drnwinga — Cominisiiionerfl of Sewerage.

Tlu' sowor arch of any required size was designed of such var>'ing thick-
ness i^iiuTcasiiiK from crown to abutment) as to resist, in addition to the

EXAMPLES OF SEWER SECTIONS

421

^ not less than 50 per cent, of the moments indicated by the
ihe lines of pressure for each of the two extreme conditionfl

ulic radius of this conduit is equal to the hydraulic radius
lOse diameter J - 0.7422H, where //is the horizontal diame-
onduit. The area of the eondiiit is equal to the area of a
diameter d — 0,SH, The hydrauHc radius of the conduit
>er cent- of that of a circle of equal area.
and St, Louis Sewers. — During 1907 to 1913, inclusiye,
oiiirtructed at Ijouisville, Ky.^ the main and intercepting
•comprehensive system of sewerage. On this work J. H.
Designing Eng., J. B. F. Breed, Chief Eng., and Harrison
lasulting Eng. Practically all sewers were constructed of
majority of them being reinforced with steel bars. The sizes
small pipe sewers up to those 15 ft. and over in diameter.
If 08 the principal dimensions of a number of the larger sewers
rent in connect ion with Fig, 151, as showing the thicknesses
ctually constructed at Louisville. Additional data con-
sewers will be found in other chapters of this book.
table number of sewer sections of large aise have been
constructed l>y the St. Louis Sewer Department, Tables
wo classes of concrete were used in tbe construction of
, according to Engineering and Contracting, Oct. 11, 191 L
Jlass A concrete had a ratio of 1 bbl. of cement to 7.6 cu.
id that for Class B concrete one of 1 bbl. of cement to 11.4
d. The concrete was made by mixinj? with the broken
el an amount of mortar of the proper class 10 per cent, in
voids in the stone or gravel.

A concrete the unit allowable stress in the concrete was
een 500 and 560 lb. per square inch and that for Class B
400 to 150 lb.

les were designed independently for particular conditions of
'atioD and other conditions, including the personal equation
ler. The Baden Public sewer arch is of Class A and the
kits B concrete. All other elUptical sections are of Class A
Dughout. The River Dcs Percys horse-shoe sections are of
rete throughout while all the other horse-shoe sections are of
Krete throughout.

1 8*ctlQii«.^A numbrr u! «ewer Mwttooa are r«pfodiiMd la Ftgi. ISB to I7S
*ir Tvtnriii tA iLiifir^ tii rlj^Mm of •tructiire« dedgn«d to oinei ■paoiAl oaodi-

P' sources imleu other wiao •t4it4«d4

1^ ' r»«e Comm., Noporwet VftUcy S«w«r, 1807» Wm. M.

Hi4 Luti-^ 4 (i. *& lu. by 4 ft. 4 1 in. Gothic iertioti. Depth of ooveir Ap>

■ It^tfTint f>scii¥ftt<Hl w»« amnd. cr»vd and clay.

I M^tropotiUii Bewerofs Ccimm. Neponaat Valkty ■ewflr, 1S07, Wm.

^^E 422

AMERICAN SEWERAGE PRACTICE

«

Table 136.-

-Concrete Sewer

Arches in Earth ^ St. Lon

1

ilori-

•ontal

diameter

in ft.

Type

Depth
of m

over

crown,

ft.

Thlckn(?aA oi coner#te

Materiitlji per lin. It, a<

Crown*
in.

Spriog-

ioc line,
in.

InvMt,
in.

.JCit.yd

Ctt. yd- vi>
eon- brick
„»,#^ inrert
"**** lifii&S

33

EUipt.

20

12

25

48

6,048 10. 471 551,23

33

EUipt.

30

IS

29

63

6.201 0 471 591.00

\

33

EUipt.

40

22

31

72

7.433 0.471 j916. 00

28
28

EUipt.
EUipt.

10
20

9
12

18
18

28
39

3.409 jo. 398 320.00
4.025,0.398 383.00

26

Ellipt,

10

9

Id

25

3.162

0,370 313,00

26

EUipt,

20

12

16

35

3.507

0.3701346.00

241

Ellipt.

10

9

18

27

3.564 ]0 348

238.00

241

ElUpt.

20

U

22

38

4,122 ;0. 348

,330.00

24!

EUipt.

30

131

24

48

4.558

0,348

332 00

23

Ellipt.

13

32

5.534

0,328

349.80

221

EUipt,

10

8

15

22

2.872

0,319

266.50

221

EUipt.

20

9

1 20

34

3,428

0.319

329.00

221

Eliipt.

30

10

24

44 ,

3.917

0,319

293.00

B

22

Horses.

10

11

18

26

3. ©49

0.320

437.50

B

22

Horae-s.

15

13

22

30

4.440

0.320

509,00

B '

20

Horse-e,

15

12

21

28

3.811

0.291

447.00

fi

20

Horse-s.

20

14

24

32

4,444

0.291

468.60

B

18

Ilorse-s.

15

11

10

26

3.130

0,262

369.00

B

18

EUipt.

......

12

......

30

3,815

0 2.57

262.60

C

16

Horse-*.

10

9

15

20

2.189

0/233

307,00

B

16

Uorse-s.

10

12

18

23

2.990

0.233

125.00

D

16

Horse-s,

20

15

24

30

3.810

0.233

185,50

D ^

16

EUipt.

11

26

31

2,947

0.223

199,00

£ ^1

I5i

EUipt,

10

24

27

2.579

0.223

193,00

E^l

151

Hor^-s.

10

13

16

21

2.670

0,226

220.00

'^1

151

Horse-«.

15

14

18

24

2.929

0.220

220, IX)

f^H

IS

Ellipt.

10

7

14

1.561

0,214

117,00

E^l

16

ElUpt.

20

9

22J

2.129

0,214

164.00

E^l

15

ElUpt.

30 1

lOi

\\\\\'

30}

2,6r»2

0.214

218,50

eH|

14

Horsc-a

10

12

18

23

2.617

0,203

134.00

D T

14

Horse-s.

20

16

23

30

3.402

0,203

171.00 1

P J|

14

Horsc-^.

10

10

15

22

2.093

0.203

236,50

B^l

13

Horse-a. 1

10

11

14

18

1,951

0.189

151.50

^^1

13

Horse-iS, i

15

12

15

20

2,116

0.189

192,50

F^l

13

llorst*-*

"20

13

18

24

2.399

0.189

216.00

F ^w

13

EUipt.

10

7

12}

1.229

0 185

99,50

B 1

13

EUipt.

20

81

191

1,593

0,185

136.50

£ 1

13

EUipt,

20

g

15

211

1.071

0.182

113 13

A \i

12

EUipt.

10

7

• * « . .

lU

1,055

0,171

100 50

%Wk

12

EUipt,

20

8

15*

18}

1 4<^2

0 171'

111 50

_E3i

i

EXAMPLES OF SEWER SECTIONS

423 ^M

36. — Concrete Sbvtee Arches in Earth, St, Louis ^^|

{Continued)

■

ie

Depth

»r fill

over

crown^

II,

Tluckness of concrete

Matemlj per Ua. ft, of

1

j VTh^rp

UMd

1

Crown.
in.

1 Sprinji-

ing tine,

in.

Invert

in.

Cu, yd
eon-
crcto

Cu. yd,

vit.
brick
invert
UninK

Lb.

tteel

»-«.

10

10

16

20

1.920

!0,174

Ino.oo

D

tens.

20

14

21

27

2.620 |0. 174 il40. 00

D

le-fl.

10

10

14

18

L 630 'o .160

87.00

D

^^1

le-e.

20

14

18

21

2.150,0.160

129.60

D

^^1

leni.

10

9

12

16

1.408 0.160

123.50

F

^^1

©-«.

15

10

14

18

1.585 0.160

123.50

F

^^1

ie-«.

15

9

12

17

1,297 0.145

131.50

F

^^1

te-fi.

20

10

14

19

1.469 0,145

146,50

F

^^1

IM.

10

10

14

18

1.507 0 145

74.50

1>

^H

e-8.

20

12

18

23

1.870 0.145

116.50

' D

^H

( ladicttied by letters in lo^t column:

ter«», Tunnel Line. D. Soutb Harlem Joint,

■

ere*. Rivrr Linf- E. Glftioe Creek Joint.

^^H

L||||i 8eetion. F. Hock Creek Joint.

■

loKctusTB 8i:w£R Archeb, Hock below Point of Invert, ^^|

St. Loris

■

■

Depth
of fill
over

erown
ft.

ThlckneAB ol concrete

Materiiilii per Un, ft. of
aewer

Where

luwd

1

\

^'^^''' incline.
*" in.

Invert,

in.

CtL yd

con-
crete

Cu, yd.
vit,
brick
invert
liniuc

Lb, steel

it.

20

12

25

25

4.339 |0. 471 405.00

A

It.

30

IS

29

29

5, 136 'o. 471 450.00

A

J

L

40

22

31

31

6. 186 0.471 607,00

A

■

i.

10

0

18

18

2,3.57 0.398 '243.00

A

^

ft*

20 1

12

18

18

2.643 0.398 243.00

A

1

A.

10

9

16

16

2.029 0,370 258,50

A

1

t.

20

12

16

16

2,256 0.370 258 .50

A

J

i.

20

11

22

22

2.814 0,348 241.50

A 1

■

t.

30

131

24

24

3.285

0,3481217.21

A

■

1,

13

22

2,785

0.328 216.00

C

■

t.

10

8

15

1.926

0.310 200,00

A

t.

20

9

20

2,374

0.319 257.50

A

t.

30

10

24

2 771

0 319J85,50

A

B±,

10

It

18

25

2,970

0.320 '

iOO <K)

B

H|15

13

22

30

^.367

0.320 :

2.38,50

B

PP 15

12

21

28 '

2.925

0,291

197 00

B

fr«.

20

14

24

32

3,250

1)291 :

201,00

B

Ps-H,

l.-S

11

19

26

2 437

0 233

120.50

B

I.

12

20 1'

I m(\ 0.257 1

150 tH)

C

J

^H 424

AMERICAN SEW E RACE PRACTICE '

i

^^H Table 137.— Concbrtk Sewer

Arches, Hock below Point or ]

^

St, Lt>ui9 {Continued)

■

Hori-

sontal

diamfter

in rt.

Tyiws

Depth
of fil»
over
crown
ft

ThickneM of ooDcrot«

M«t«riAl4 per lin. ii> of
■ewer

Jl

UMd

Crown,
in.

9pdng.

init line

in.

Invert,
in.

Cu. yd.
eon-
Crete

Cii^yd.

vit.

brick

invert

lining

Lb,elw

16

HoFae-6.

10

9

15

20

1.833 0 233

120.50

B

16

Horse-e.

10

12

18

23

2.160 0,233

102.50

D

16

Horse-«,

20

15

24

30

2.720 0,233

143.50

D ,

151

Horse-8.

10

13

16

21

2.041 0 226 141.50

F

151

Horse-s.

15

14

18

24

2.222

0.226 141.50

F

14

Horse-«,

10

10

15

22

1.622

0,203 84,50

B

14

Horsc-«.

10

12

18

23

1.952

0.203 112. fiO

D

U

llorse-s.

20

16

23

30

2.478

0.203

139.50

D

13

Horae-s,

10

11

14

18

1.605

0.189

94.50

F

13

Hor8i*-s.

15

12

15

20

1.608

0,189 1118.00

F

13

Hor^-«,

20

13

18

24

1.891 0,180 134.20

F

13

Ellipt,

20

8

15

IS

1-167 0.182

88.50

A

^^^^^^^H

12

Horses.

10

IQ

16

20

1.542 0.174

89.50

D

12

Horse-«.

20

14

21

27

2.599

0.174 '114.00

D

11

Horse-s.

10

10

14

18

1.360

0.160

71.00

D

11

Horse-s.

20

14

18

21

1.680

0.160

106.00

D

11

Hurse-«.

10

9

12

16

1.099

0.160

80.00

F

11

Hor8e-«,

15

10

14

18

1.224

OJflO

80.00

F

10

Ilorse-e.

15

9

12

17

1.017

0.145 77.50

F

10

Horse-e.

20

10

14

19

1.139

0.145

85.00

F

10

Horse-s.

10

10

14

18

1.137

0.145

64.00

D

10

Horse-8.

20

12

18

23 1.350.0.145

92,50

D

ATote.-Lg

c» lions indi

«aled bj

f letter*

in tiut column:

m

^^^^^H

Dea Peres,

TuntKfl

I me.

D. South HjLrUm Jolnl

_■

^^^^^H

De# PercB.

River L

loe.

E. GJiitae Creek Jmnt.

^B

^^^^H

public, Ut

SeoUoo

F. Rook Creek Joint.

H

^^V Tabl£ 13

8.— CoNa

IBTB S

BWER

Arches, Rock abovs Powt of I

^

i

Jr. Louis.

Mori-

•OQtlll

rliftmeter
10 It.

Type

of ail

over

ft.

TbickneM of poncTete

Matcriitli p«r lin» fi, of
■ewer

4

Crown,

in.

ingbne ^
in.

Cu. yd.
Crete

Cu.yd.

vit,
brick
Invert
liiunc

Lb.»iMl

22

Horae-fl.

10

11

18

18

12.782 iO 3201200.00

~^H

22

IIor»e-i».

15

13

22

22

3 1 > 50

^H

16

Horses,

10

12

18

18

l^ '50

^H

16

Horsc-s

20

15

24

24

2 50

£^B

151

Horse-B.

10

13

16

10

I ' 50

^H

15i

Horae-fl.

15

U

18 1 18

2 ] 5(1

^H

141

Horw-e,

10

12

15 1 15

1 7_ .. .,J 50

jBB

i

EXAMPLES OF SEWER SECTIONS

425

JthBix 138.— CoNcsETE Sbwur Archbs, Rock abovjc Point of In'\ert,
8t. LoiTta (Cvntmmii)

toft

Tm

Deptli
of fill
over

crown,
ft.

Thicknen of cooerete

MMterittU [>^t lin. It. of
B«w«r

Crown,

hi.

Sprios-

tug Line

In.

Invert,
in.

Cu. yd.
cret«

brick
in%-ert

Lb. tt«N>]

Where
u«k1

14

14
13
13

L 13
12
U
11
10
10

Horse-***
Horse-s.

Hor9e-«.

Uurse-tf.
Horse-s.
HoreeHi.
Horse-s.

10
20
10
15
20
10
15
10
15
20

12

16
11
12
13
10
10
9
9
10

18
23
14
15
IS
16
U
12
12
14

18
23
14
15
18
16
14
12
12
14

1.663
2.075
1.435
1.621
1.777
1.286
1.104
1.039
0.945
1 067

0.2a3
0.203
0.189
0.1S9
0.180
0 174
0.100
0.160
0,145
0 145

80.50
137.00
94,50

118.00
134.00
89.00
80.50
80.50
77.50

sn no

D
D
F
F
F
D
F
F
F
F

SMi.—LiMmXioua indtcAted by loiierA in liwt oolutnn:
.A Rirw D^ Pcrei, Tunnel Line, D. South Htirtcim Joint.
Ill ttirnr D**m Perm. River Lino, E, Glniae Cret»k JoinU

IC Bideti Public, 1st Seoiioa. F. Rack Creek Joint.

hnmpA^ Jr., Chirf Enc* ^ ft. by 4 ft. t| in. Qothic voction. L«ft hiilf of figure oonntruo^

' tionel; right hmlf construction for tutmrl in hurd irricvelly scul.

l*hil«delpbiii, Pb.. mM. C#*?o, S WiUlcr. Chirf Eng.. 4 ft. » in standard cir-

ivrr. The left half ebc)W9 nirnimutn dttctton; riieht half enDstnicUQn In ** reduced"

9tMll rcinforodn« ovi^r piled oqu&l to 3/4<in. squ&ro ban 12 in, o. to 0. Piles* 19-

ap&rt both ways.

lelphiA, P&.. stAnd&rd iewer nection, 1906, Qcto. S. Wt^bsivr, Chief Eug.

wcr, Riicht half of scocion. construction in 'Vmaxiinura crndle," on piles

tft. fllB G to p, tmn^vRrsely, and .1 ft. «. to o. louiittuirlinuTly. StepJ reinforcing over pilc«
•Qoil tid Sr'i in. BiiuArp bsrs 12 in. o. to C, Left half of «H*ctinn. eoti«truetion on pUtform and
FlsClorm of G-in. yellow pine planking on 8 by 8 in. yellow pine stringers 3 ft. apart
dly. Piles 12-in. yellow pinet *^ ft. apart longitudinally and 3 ft. 9 in. c. to c.
«ly,

Fig. l$:u. — Tniro. Novti Seotla, 1002, Left A Coffin. Eng,, 27-in. circular sewer, monolithic
t tti springing lino of liHck nrch. Concrete tuted be<:au«e of cht^apness under given
I pompari'd with bhckwnrk, Kng. Rec, Aug .'10, 1002.
r-'Philadelphis. Pa » Magee St. sewer, 19WI Geo. S. Webster, Chief Kng.
Itii. drciilaf. I»fi hall of section, cciiistruction in «»fth cut on piles with earth cover*
tfwm yellow pin**, iMn, planks on 8 X S in. <*ap« with 12'in. piles set :i ft. c. to c. in eaoh
Kliniu Right hulf tit the itiirrtiou, «otistructlon in rock cut.

IS4* — Bcirimgh of Brooklyn. New York City, Gold St. Relief Sower, 1007, E. J. Fort*
<Riig, 1.1 ft 5in ♦■ircMiUr itcctton. The figure shows two mcthofls of construction. In
^Uurd metjiod the m'ftiuo wa^ built entirely of conerett* with 10 in thiokrir.««t» fti thr rrnwn
^%h'^ .i.Mn.rin^ llue^ A fourth typo had a segmcotal e*incrt»le arch »nd concrete
neral <1iincnsiuati ua the left hwif of the section shown. Platform
oti 4-in. nill«; pUtforin on piles, eonstruct«td of 6 in. plank floor
capping ou la-in. spnuvi or pine piles, tpaci^d M ft 9 in. o. to c,
_ ugh of Qunenst New York.— Trunk sewer In Myrtle and 91 NicHolaa

il. U. Johitton. Chief Eng,, 1^ ft Hrcuhir AoctloQ. Depth of cover about Ifi iUl
In dry ^mdy •ail. lUnitforced with Johnson eomigated bam '* new style;'*
»T - riffosb^m. tin., 12 in. c toe: londludlnal

V ft of the tttme general form; 11 ft. 3-ifti

IU.,i u,M -, i.1 ...►^... .1 ..:... »' ' -^nirnt »»iu l&-ff •<?«'*i»«>

inntaide tJ*Asver«r rT«i# »« under 4i ft. bad 3/4-

tJ^ tranrrerM mdm^ l.^in. on iual rods over crown and

dta^MKH

^MEHlCAf^ SE^^^

AGE PJ

Undtf^f^'^

.V^ ^

& ^

^ T »'

I'pfffS^''

T r u

r o.

i^ihbfick.'''**^

-fio*

15S.

^T

428

AMERICAN SEWERAGE PRACTICE

bmuicbei. Arcbw in all ■ections 0 in. thick At the crown and 6 to 0 In. at aiirififint ^^^
from 4) to 5f ft. diameter, Incluiive, reinfort^ed with 4/i*in. lateral ruda 12 la. ti
tore and 3/44ii. tongitudtxui) rod« IS In, on c«nt«rs. Areb fins' ^ t<) ^ ^n ihifiV nt
and 12 to 16 ia. at ihc ttpriu^tii; line, Th« fl-1 / 2 tirtd lU-fi, »ecti
just d«*4CMiVM!!d« The thicknc^sa at crown and apHnj^ing tine of Vt I
12 And 24 Ed. rr^pectivrly for both sisea. At one point, oover <>

deep; eii«c9 f mm 5 J ft. down bad RtolOft. of cnm. Praoticitll, r., ...' r

IlcfiTenco, Eng. Rtc, vol. Ivl, p. 590*

Fig. laic. — Des MoinM. Iowa, Ingcrsotl Run Sewer, 1905. John W. Budd, '
drcular flcwer, with l/2-in. tmnaverBe burs 12 in. o. toe. and 1/4-iu. Uxi.
spaced as shown. Eng. Rec* April 28, IQ^OO,

Fig. IMd, — Toronto, Canada. High-Lovvt intercepting newer, IQlO, Charlw ff
City Eng. Circular roinroroed (sonrroto sewer on concrete piers or-
Tmnjs\"isrse bars, 5/S-in, on 4-in,c©ntcrB: lon^ttudlnul bar*^ .'i /8-in- ro»J* i
below RprinjcinK line, vitrified brick. In treofrh, aet'tion was plain eonrrftt w u n ^ n r^nr^
invert linine. TKickncMat crown waa 12 in.; at springing line* 17 Jf In.; at lnv*n.

Sft^l Plafms

IlKf

liia;

d Piank
Toftqued

Massachusetts *

-a-

Clev«lar^d

Fio. 155. — Typical circular Bections.

^b-

iQV«rtbcIowbri(^klining, 7) in.; maximum width of plain concrete Miction 11 ft $la.:e<
ereieinverthaa horizon iai base 3 It. 6 in, wide a ndita aides i;lo][>c up ward Zftrdkn.'v
in a horiiontal dlstaoct! of 4 ft. i in. EnQ, Rec, March IS, 191 L p. :i(H.

Fig. 154r.— Wilnan^ton, DeL Price** Run s^wer, 1903, T. Cbalkl<»y HaUon,(
Eng., 6 ft. circular »rclion. Loft half for MuiUow cut wbcrts srwvr v:-.- ' - - '- -.'-■--
used with and without phi^tforrn. TUicht hnif, mmMnioritju r'n»ir* '
thickmi«a of only 5 in. ttt the erown» the scetiona witlistocHl willu i
will be subjected t.o at any time. RcLnforoemmit, woven aim fabric of >
wire selvage and 0 X 4-in. niosh. A Ofr ft. acwer of atiiuo typo with ^
constructed, butad-ft, 3-in. section bad u crown thickness of 8 in,, 12 in. nt ih«> ^pnagiv^l
and 8 in. of concrete At invvrt in Bcciion like rijtl*t halt of figxtri!, Several hundred Iff**
this 9-ft- 3-in. section were btdlt on pine pile* 30 to a ft, long, four pUmb to irar.h MJl,i(p««^
3 ft. 1ft i in. oent.crs, and bents 4 ft, between oenten^. Eat^h bent bad a 10 X li*«a- P^

pine oftpcurr>'irjic floor of <3 X 12'iu. bemlor^k. Reinforoement, r^. < < - < ' - *^

No. IJ gage, approximately 2 in, from lliR inner surface. iSng l<

Fig irn/.— r,Uft0.iBt<^r. Pa, 1W»3, Sr^muMl \1 r.r.. Vni: «.-lt

forcpd with 3-in No. JO exponiled
burned or ^iitrified brick. Alter nun

I

ft

1^^- t^miiied to require 2 in. mnffi dUmet<«r» giving 3S.i8 iiq, ft. aei nffAiriat

"t*" (H'Wc'f; had thnw ringrs brickwork oo connret*' hASv 9 ft. widiv fl in.

* "f invert wad fXte»tUng verticttUy on iidoa to apringmic line, Alter-

«»•* ! inu, ft. brick lintl 15.48 cu. ft. concnpti* per lineur foot; quantitiva

'*"" *d were 13.70 cu. ft. concrot© and 4. OS eu. ft, brickwork. Sewfir

ciMkstruruHi tkm tlluatnited oo Account of the greater eompnrotivp economy.

_ Ff-^ t.V%a ^^Mms, Metropolitan Sfweragcr Cornm.. North MetropoUtan SyHem. 1603,

i. Cmrmon, Chief Kng., 8 ft. 10 In, X 9 ft. 4-1, 2 m. Gothic section: built in pncumAtia

lift day underlaid by very wet miiid. Aa ua indic&tion of the extent of ground-

1 "'fie point it WM impr»»aible even with five oompre«sor» running t^ excav»t«

I an 1\ ft, to grude of bottom of miwonry until following method wiw

'dV ork stnrted na low a« possible i%nd concrete lining used for aidea. roof and

! «ng Th*» 2At\ tongued and grooved plaoka m^t radially, prevented wet sand flowing

t th» biitttoin, l^pp^r pi^rt of arch eeeurcd by 1 /8-in. by !-ft, by 3-ft. curved ateel pLatea,

« v-^ Id, r«cli othar and supported by B X 84n. temporary poata. With ooncreto lining in

»-'*- ft wn" p'MwiWo to hold air prenur« nod allow remainder of excaviition to be made and

! linings net. Blde^i and bottom of aeetion held in place by 2-in. plank lAggin^

it with i»rdh built fimt, same reflulta were obtainable without uoe of concrete ,

^MitK on wntl plnt'TiA. these and arch supported by braces from axial be*am; invert

• up ti» wall ptiUeii, j»nd the vpaco loft by removal of wall plates filled with brick.

i(*»« i\lwaya 12 in, thick, l?»tf. Ntwt, Feb. 8, 1894.

<^«„* ! <*luvelandt Ohio, Walworth Sewer. 1808, 10 ft. 3 in. circular aeetion, very

^•"•'fc':* n », r^unt of yielding plastic blue clay, unable to carry more than 2 tona per square

■ •^►^l, ThleWnrai of arch incrcMi^ed gradually from crown to springing line* and arch brick*

»r«^5t^ij^f jn jklt4«rnale headers and stretchem in Flemish bond. To avoid exceaaively thick

^' ' uita manonry was broken up as shown. Entire arch cut into segments aeparate^l by

*^ 1 «urfare« and radial ph»nes. Inner and outer faces of brick parallel with inner

^''1 .■ I l.-ted «**'WL-r, Number of courses to build any partieulnr cylindrical segment

the number in next inner iiegtnent, and one less than number in neitt outer

**^'^ '■ Mil,'* of ofdinarj^ ihickoc^ were thus obtained in all portions of arch.

■niHT and outor rings of aegmenta, as well as extrados of arch plastered

r mortar. Kadial thickness of each pari of superimposed masonry

! I I M 'M k joints in adjoiniog segments by at least 4 in.

I i-uii >>:iK [>lank, laid ncroas aewer line on 3 X 12'in. oak sleepers, nol more

i ft. tj. Ui d, biMJded in clay. Entire lower portion natural cement concrete. Top of

"^•tff brought to plane inclining downward and inward A horisontal to I vertical. Mini-

*''i»a thiekneas of coiieTete under two rings of lining brick of the invert, 1-5 ft. for sewers

**«»iti 8 It. to II fl, 0 in. inelucive, and 2 ft. for larger *iies. Side walb brick laid in English

- 1 cement mortar, carried upward from concret,e with courses pitching inward

4fl»er >*iirffi^e of the concrete. Two concentrio rings of brickwork in invert

I aov, in order to obtain a smoother inner surface.

^ < L»«i fitoil afbitrarily according to conditions in each case and thieknoss at

i'terrninod by formula given earlier in Chapter XI. Thickness at any other

^AHLE 139. — Priptcipai* Dimensions or Walworth

LAXD, Omo

^..

Se:weR| Clbvb-

ThiektiesB of masonry in feet

Ott

hoHs.

Cfown

line
0tron«h

J. I

2.5i

11

2.07

I 6

2 02

t 5

2 98

' 1 h

3 It)

1 15

3 3«

Center
of in*
veri

2 2fi
2 25
2.25
2 25
2 25
2 25

Width
of eon*
erete
foun-
dAiion

Thickness of masonry in feet

Di-
ameter,
It, in.

Crown

16 20

17 08

18 84

19 2tV

20 14
22 26

12^3

14-9
l.'M)

15-9

16-e

15

1.8

On

horia.

Mne

through

center of

sewer

:i 554

82

07

u

26
39

Cent<»r
of in-
vert

2 25
2 25
2 25
2 75
2.75
2 75

WldtW
of con-
ereti*
foun-
dation

23 54
25 61

27 70

28 M
29.58
30 78

430

AMERICAN SEWERAGE PRACTICE

f^h^ ladelphia.
Fio. 156. — Typical eggnshaped sectioDB,

EXAMPLES OF SEWER SECTIONS

431

kUttminod by drjiwinji «tc of drcle through tbeafr t|)v'> potati, Ihta hra hnvinit ita
\ bf^low the eenter of ihe aowcr. Below npnngitit tia«« w«U hiul batter of I hori-
iietkl.
I of vsriou* dianietera were coDatrucied aloDit K«n«ritl pt«n of auction nhown:
■inrw of sevenU are g:iveo in Tnblc 139. Tb« iovert ib uaeb MM» wm lined
I of brick, a totat.of about 9 in< In tbickn«M.
e»ctii>n« ar« noteworthy for heavy masonry to retain Unu of resiatanon within middlo
NBlioa At all pointii and to spread thrust on soii to reiiuoe aotl preasure to not more
^^bcr s«iuaru foot. Sevtlona also noteworthy on account of construction of arch
^H^l bondtnjc (if thu brickwork adopted as productive of a much moTc s^table
^Bl would rrAult from uae of ortlinary bond, Trana. Am. Soc^ C, B*, December,

njrer, \

to, — Worcrator, Mass.. 8ew«T Dept„ 38 X ."iO-in. brick, egB-ahapod sewer, typical

ictioo uard rateitisivcly in many old systemji throuifhout the country. In recent

\t, thift type haa been replaced largely by »cetions shown in Figs, I5Ac, d, e and

- old sewers show but few aliens of distortion due to earth presflures. Whore

built on 9tx<vp eradea in combined syntetoB the invert bricks have been worn to

I extent and in some eases worn through, caueing back filling and supporting

idde of bfickwtjrk to be washed away and resulting in caving in of aewer. This

! init invert moAonr)^ heavier and lining invert with hard-burned or

I to n^sifll w<»ur better,

/. - i' . , Mas*., Sewer Oept., 48 X 72-in. hriok, ogg-«haped sewer, Interisst-

^ount of wpedal ahnpc used in several instances in that city.

^-Borough of Brooklyn. New York City* l&Ol, H, R. Asserson. Chief Eng.,
E-ehapml sewt^r. with two types of cotwtruetion. This acwer wns designated
the equivalent circular sewer instead of by dimensions of the cgg-ahaped

f-Borough o! Brooklyn, New York City, Bureau of Sewers, 1013. E. J. Fort,
•rd ^t^hi. egg-ehaped sewer of much interest when compared with Fig.

^Philadelphia. Pa.. l(KHi, SUodard sections, Geo. S. Webster. Chief Eng.,
hf t^ egni'iilmpcd sewer. Left half, construction in firm material when minimum
used; right half, construction called ** reduced*' cradle. Reinforcing bars
nl in area to 3/4 in, equare bars, t2-in, centers. Piles 12-in. yellow pine 3 ft.
dinally nod 3 ft. 4 in« transversely.

^Philad«?lphia. Pa, Standard flections, 1906. Geo. S. Webster, Chief Eng.,
■ft. egjt-sbjtpeH aewer. Left half, construction in ** ma^mum'* cradle on pilca^
V rdent to 3/4 in. square bars 1 2-in. centers, piles 12 in. in diam-
»i 3 ft. [ !y and 2 ft. A in. transversely. Eight half, construction on

'• rm 6-jn. yellow pine ptanking on 8 X 8-in. yellow pioo
ft. apart longitudinally and 2 ft. 7 in. apart transversely.
. ^ 1 . iii^ide below springing line baa one ling of vitrified shale

|>Wnrnwster, Maat., Sewer Dept,, 1890, H. P^ Eddy, 8upt., Water SI.
pverted cgg-ehape int^^reeptrr. Average depth to crown of sewer, 17 It,
iml in tunnel, largely rock but partly earth roof retiuirtng bracing. Sec-
r its economy of »paee with wooden timbering and the additional Inside head
tdable.

,Ti. _\i_.. \i. .. ,, ||t^„ Sewerage Comm., 1891, Howard A. Carson, Chief Eng.
utrnll Si<s^of« Deer litland near pumping station. Catenary
;>fb of coYcraboutHft. Section designed to act under slight
k made extra heavy (o produce eiee«a of downward pressure. BnQ* Ntw$t

i, ¥ and /- — MaaaaehuJiettJi NfetropoUtan fkwerage Coram.. North Metro-

aertion So 2rt, »HW2, Howard A- Carson, Chief Eng, Catenary /i| X

Condifi' Hy permitted building invert in eicaviition without

jbUofi. N< intti'c was in ctay permitting an all- brick sectiuo but

^y " reiuiriiig vnriou* forms «hijwii. The entire length was

||t' f*| ay or concrete bitcktill beiween plaitorm and fwcr.

11* n l.')7e right half was uacd. Average depth of M\ for

about 17 ft, Average deptli above crown of tower to ■urfaee of

etion, about 34 ft. Khq, ,Vm«, Feb. B, 1894.

432

AMERICAN SEWERAGE PRACTICE

Induraffd
day

Comrtfe

Comrete

Sand
Ofovet

}■

Fro. 157,— Typical in

EXAMPLES OF SEWER SECTIONS

-a-

NVa sHIn^ + o n •

-3'S'[

Massachusetts.

5] iP"*-

^ \

f?" \ ••';• Mi \ / '
r-.j'e"- V/^i>j k^'c?" «-3't?

xO \i !.• */ \

Altoona. Richmonc*.

Fio. 158. — Tj'pical elliptical sections.

434

AMERICAN SEWERAGE PRACTICE

Fiff, ]58<i. — ^Watihincion, D. C.« main conduit nejur pumping ttmliQa, lOTM,

office of Engineer Coramiaadoner, District of Columbift, Oval i» X 7»lt. I^in •••^••r
length oi Miction eonnectfl muio 6 X O-ft. liQrBc^shoe ««wer with trunk sower, aiiU i
into cunettc in et-ction shown In Fig, 168c.

Fitf. 3586-— 'Wftahington, D. C, low area trunk sewer, 1905, d«fttgnf«Hl in ofRc« of Eft
CommiRRioner, Diatmi of Coluinbio. Oval 4 X 0-fi- vcwtT. i\buui 100 fi. buOl^
fiPcUon and Fig, l%8a Bl^k•cU>•j to fill flpeciftl rfquiremcntd.

F%0. 15<S^.— Chicago. 111., WMtem Ave. »ew«r. 1910, Ishjum Rmndolpb. Chief E««., 8*^
lAry District o( Chicago. Elliptical 12 X 14-ft. sewer ExcnvntJon scnvmUy lu scilf tJ^
day, average cover, 10 ft. Iniide traneversc bare, 5/8 in, square. 12 in. c, toe itmitmfsm
extrivdo<9 Wra. 5/8 in. aquar«, 12 in. c. to o,: longituiiinal bars, t/i in. aciuare 24 kh «. !••'.
Rrinforoomcnt used in but few places. Under Illinois & Michigan CaiiaJ, ceetiUrn chi^p«d
to 12 X 9'ft. ellipse for distance of 60 ft. long with 5-ft. full in tbal letictl^ JTa^aacnvi
and Contmciina, May 4. 10 lU, Feb. U. 1914.

Fiff. l.V*W, — Mas*. Mctrooolitan Sewerago Comm., North Mf*tropolits^u Sewrr, SerltM
41, 1892, Howard A. Carson. Chief Eng ElUpticAl sewer, 1 ft. 8 in. X 2 ft. tt is^ .Ivtr^t
cover, about 10 ft. Excavation in aaod, gravel, ledge, boulders, filUns and r^ry Sue* aa4
containing much wat^r. In plaei^-s the fine sand wap removed to 1 ft bdnw bottom of ir^*
and replaced with gravel. In other places, piles averaging 2o ft. were driv**n, >>fT7Hf 2 ft -a
centers, with 8 X 10-Ln- caps and 2-in. flooring. Lodge was rw plant!*! by
in. below bottom rd brickwork. In sand, cticavation carried to firm ^
brickwork bedded in and surrounded by gravel. In fine running isand.
of 1-in. boards on 2 X 4-iu. ribs, and cradle covercfl with brokt*n stonu, «

paper. Another section bad cradle of two tbicknessi^ of boards with ; ,. ....^ . .. >

Eng. iVw«, Feb. 8, 1804,

FiQ. 158<.— Altoona, Pa,, 1896. Oval sewer, S3-1/4 X 44-io, Section bad i»ti»-nr\i hrii-
work and 4 to 8 in. concrete, with invert of vitrified shale paving brirk. P.
b« less than cost of two-ring brick sewer. Froc. Eugr. Club of Phlladclpliia. .
page OK

Fiff. 15a/.— Richmond. Va., 1912. False olliptioal 8 X lO^^t, and 8 X U4I, <
chosen on account of insufficient depth for elreular sewer. Curves of arch ami loftH i
ihree-ceutered, with row of headers at point of change of radinn to tie tb#« hue* <
On account of shallow cover buttreases were built every 12 ft, to give arch - '-^ '■*
against sides of ditch. Double-track railroad crosics sewer with only abo
Portion constructed in 4 to S-fi. rock cut, where concrete invert lined with t riri,
arch of 3 rings of brick were used. Fig. 15^ shows one-half of etch of ib« two «
Mnginefring and Contracting, Nov. 20, 1912.

Fig. 159a. — Mass. Metropolitan Sewerage Coram,, Nortli Metropalitan Bi*wi -
1892. Howard A, Camon. Chief Eng. Basket-handle section, % H. 2 in by » i
half of section. Construction in firm material where bottom could T< ^ '

half, flonstructian on timber platform on piles. Platform was 4-iii : H i

caps, on pilei* jspaeed 2 ft, 7 in, centers transversely. Bng. New»>, I . : i

Fig, 1596. — Mass. Metropolitan Sewerage Comm.r North Metropolilan Sewer, Coitf
Section 14. I89:J. Howard A. Carson. Chief Eog. Basket'handle sewer, j% (t 4 in X Vl

2 1/2 in. used whcro material below springing line was sand and gravel and Uiat ftbvvf <
clay, Bewer arch backfilled with gravel, Eng. .Vetcf, Feb. 8, 1894.

Fig. 159c.— Washington, DC , Outf^ill Sewer, 1904, designed in ciffiee of EfiglOMT Co^
missionerof District of Columbia. Basket-handle section. 0 ft. 4 in. X 8ft I in^ IsllMI
construction in firn) ground; right half, construction in yielding soil or in insiw-upe |
Several hundred feet on piles, masonry section same as right hail of figure Pile vpoiciJl^ *
in center, one on fitber side 3 ft. 7-1/8 in. from center, and one oMtsi*<" '■''■

3 ft. 4 in. from center of neit adjacent pile, making five pil«JS to bent, Ihm
0. to o. Another section built on 3-in. yellow pine floor on tU X Vl-iu. '
bent* containing mx piles, spaced 2 ft. 8 in. on centers.

Fig. 159ti. ^Pittsburgh, Pa,, Try St, drainage sewer. Bureau of Surveyn. rh«f»*# 1
Heppert, Div. Eng. Basket-handle section 7 ft. 4 in. X 7 ft. 9-1/2 in. i • '

tion for firm ground: right half, construction for soft foundation. In Uti
0 in. c, to e. were placed in invert. A «i-ft, S-in,, X 7-ft. l/2-in. section wn*- ru*. i ronitTM"
9 in. thick at crown and 18 in. at BprinicLng line for (irm-grotmd secrion and .^OiikfofH
ground tection: and invert below vitrified shale brick linifu' mu, tfii.k \! a vi 1.111.11 •idik^_

436

AMERICAX SEWERAGE PRACTICE

i'PfMftr

-C-

15:* I*! rnore.

-b-

Martford Aqueduct.

■ 2// • »J

-d-

Watcrbury.

B O S "t- o yn
Fit IW.— Ti"pical horse slu>o Kirfions.

EXAMPLES OF SEWER SECTIONS

437

^Itw 8 in. uid 1 1 ft. 8 in. lor firm- snd aofi-sround nctiooft r«sp««tively. A d*f t
l^^l/2-in. teotion was Sin. thick At crown and 16 in. at fpriniE^ lini> 'or 5rm>
■nod 2S in. for »o{t-ground section. Thjckneia ol invert below vitrified
Hue, 6 in.t m&iitnuni width of mAsonry* 8 ft. 4 ia, »nd 10 ft. 4 in.> respectively
^ 4Dd Boft-grouDd sections.

^Jerw»y City Water Supply Co,, Jersey City, N. J., aqueduct, 1903, E. W.
hieif Enir. BaAket-handle »ectioQ. 8 ft. 6 in. X 8 ft. 6 in. Left half of illuitra^
liction in »oft earth; right balf, M!!Ctioa built on embaakment. Transverao et«ot
iiL,3/8-in, twieted rode I2in. on centers; lonidtudinAl bars, 1/4-in. twijted rodi
■IfTi. Lower part of invert of soft earth eection rGiniorocd with 3-ia, ni^vh

I id metal: invert of section on embankment reinforced with 3/H-in.
nrhere cover was about 15 (t., arch was 8 in. thick atorownandBide wolLi
•prInicinK line. Bng. Rttord, Jan. 16, 1904,
^ewurk, N. J.« Water Dept.p Inlet conduit in retenroir, 1901; MorrUi R.
\ Basket-handle section, 5 X 5 ft. Reinforcinc metal. 3*in. meah No. 10
^tt from reterToir oomprisea two conduita similar to one shown placcil side
•Iween two 10 in. thick and space between extradoe of sections filled with
Sk.latimuin width of doubl^oooduit section, 12 ft. 6 in. Both single and double
tiofis have comparatively heavy walls to provide sufficient dead weight to
luoyunt effect of conduits when empty and reservoir full. Test section of
luit subjected to hydrostatic pressure up to 34 lb. per square inch without signs
I, Eng, Ree„ Dec. 12, 1903.

u — ^Wachusett Aqueduct. Mass. Metropolitan Water Works, 1897, F. P.
[ef Eng. Borse-shoe secUon. 11 ft. 6 in. X 10 ft. 6 in. The figure shows oon*
ro(<k cut, and by full and dotted lines the types in earth from bardpan to soft
irer shallow; about 4 ft. for a considerable distance. Eng. Neva, Feb. 25,

Eford, Conn.f Aqueduct, 1912. C. M. Saville. Chief Eng. Horte^ho^
H, X 0 ft. 9-1/2 In. Largely in earth trench i^'ith about 3-ft. cover,
loltimore, Md., Outfull Sewer, 1907. C&Uin W. Hondrick, Chief Eng.
«. 13 ft. X 10 ft. 9 in. Left haU, construction tised iD tunnel or abeeted
^i half, type in loose earth or fill. Eng. Rec, Feb. 8, 1908.
, — Waterbury, Conn.: main intercepting sewer, 1907, R. A. Cairns, City Eng.
•bape, 4 ft. 6 in. X 4 ft. 5 in. Tranaverse steel reinforcing bars 3/8 in. square
».! longitudinal bars. 5/16 in. square. On soft bottom footing extended S in.
icsJ walls. About 1500 ft. in river bod constructed with much heavier section
sluing wall. Eng. Record, April 4, 1908.

, — Boistan« Mass.. Tenoan Creek conduit. 1909, E. B. Dorr, Chief Eng, Hone-
14 ft. X U ft. 6 in. Transverse steel 3/4-in. twisted bars 12 in. c. to e. The oon<
Kflroeted on piles, 4 to a bent placed 5 ft, o. to c.

^'-^Boitlon, Mass., Tenean Creek Sewer, Brick horae-shoe conduit, 14 ft. X
I Is much older than Fig. 160* and afFords an Interesting comparison between the
hods, involving the use of a brick uroh with concrete backing, and the modern
fOfMd eoncrete construction. Structure built on timber platform of 4'in. plank
bl

ga« Moas., Marginal oonduit, 1908, Charles River Basin Comm.,

[ Eng. Horse-shoe section, 6 X 5 ft.

N. y.. Main Intercepting Sewer, 1010, Intereepting Sewer fioftrd*

, Chief Eng. Horse-shoe section, 6 ft. 7 in. X 7 ft. 3 in., equivalent to 87-

dler sections built of tame general form with tliinncr masonry. The

. 4-tQ. section had 6-ln. crown and invert thickness and 10-in. aide^wall

\f. tropolitan Sewerage Comm.. North Metropolitan Sewer, Section

ru Chief Eng. Horse^hoeor basket-handle section, 3 ft. X 3 ft. 3

. m v«iry fine running sand on S-in. plank platform on 8 X S^in.

^li, «. tv e.. two piles to bent. For short distance on clay foundation sewer

n. boards laid on 2 X 4-in. ribs; constructed entirely of two rings of

■ X^u>«, Feb. 8. 1894.

er. Pa., IWKI, Hamuel M. Cray, Etw, Horto-ehoe aoctioo, 7 ft, « In.
I shown In lafl half oontaioa 32.6 cm. ft. brickwork and 4.8 cu. ft, eon-

438

AMERICAN SEWERAGE PRACTICE

Cambridge.

i l^

■ ••I iM»-*ls<ir»

I Un^€rif9*ti

Philodetphlci.

Fia. 161 — T>^pl

,iM#"^

Moi5sachuMir»»
t 90Ct(QDB.

EXAMPLES OF SEWER SECTIONS 439

"vl^ pet llMKf fool: type thown in right haJf ooDtaiiui 24.7 cvt. ft. brickwork and 18.5 cu. ft.
•Otticrru. 8»Qiloajil art*!* of wiiterwti>'« 50.4 9(\. ft. If constructed of coacrete. «octioaB could
be rKducfd lo 7 ft 4 in X 8 ft. 2 in. with the tome KQaernl ohApo. CoocrGtc i«ctioQ in
tQc^. lhicktt««i wjiif ((in. ttt crown, 9 in. atspringinis line and Oin. eit invert bcSow vitrified
butk Unlof. Hrtntion reinforced with 3-tD. No. 10 etpunded metal. Section contnined
J -11 ff .,f KH. Lr^.ri .....I ,^ff,J^ q( 1^-aterway wa,« 49.00 wj, ft.

,, P%., Anunbury St, Sewer, 1009. Geo. S. Wchat«r. Chief Ena .

: ! fthoe Mctiou, 17 ft. A in. X IT ft. 6 in. Built geocrftlly in ahullow

I ft cover over the top of tlic »cwer. Fig. 1556 showa another type of brick odd*

i of itttcrasttn conipunnon with thftl in thiJi fiiur«.

fi^, mif — MiuiB. MrtropoUtan S^'Wi^rs-go Cornni., 8outh MetropoUt&n High Level

S*»*r, IW3. Wiiliam M. Brown, Chief Eng. UorBe-ehoe type. 10 ft. 7 in. X 11 ft. 7 in. Con-

«»*» vmi gmerAUy for m\tf wrilla and invert backing, with one or two ringn of brick lining.

•H&MwIitit upon amount of ground water. Concrete occasionaUy used for arch, but arcbca

• f, rrL...ft. 1 * ,.- brickwork.

iile. Ky., Beargraaa Interoepter, Suction A„ ll>08» J. B. F. Breed.

' -Uoc sectioo, 6ft. 6iii. X Oft. l-l/2in. Left half , construction in open

i«i «>th i to ti-ft. cover; the right half, type in tunneL Excavation in clay and land;

***'^ «-ntmti}tered in open cut. The Mteel reinforcing bur* for the open-cut tection were

-^ TrantveTM? arch bara^ 1/1* in. equare, 9-1/2 in. c. toe, Ukemise aide wall and

.r«: tongitudinal bare were 1/2 in. Aquana, 13-1/4 in. e. to c. Oneaection bultt on

■ Milt 20 ft. in bent« of three each, 4 ft. on centers. Portion of tunnel Miction

' u» pih'8, in hol» bored with augur, making the Anijihed bote 10 in, in

.4i»U"r]ul enrountcred a filt of clay and mud. Vertical iteel reiaforcement

I warh hole and hiJo tb»«n filled with concrete. Sotne material encountered waa

t mucky, thnt vnn*'r"'U} wan placed through iron oaaing withdrawn as concreto

tn anoth^T seelion l2-in> wrought-iron pipe casing was driven and concrete

Lt tfithout reinforcement. Moat tunntil work was in dry looae running aand.

"tectioii of the tunnel was backfilli>d with concfote to a point 1 ft. above

f aewer arch.

.: l^uiBville, Ky., 34th Street Outlet Sewer. 1»O0, J, B. F. Breed, Chief Eng,

? aectlon, 7 ft. X 6 ft S in. Maiimum cover, about 25 ft,; average, about 10 ft.

■ ' -yr^ly in eand, gravel and clayey loum with some loose rocks. Transverae

, 1/2 in round, 9 in. ou centra; longitudinal bara, a/8 in^ round, spaced as

r uf eewer below Hpringing tini* lined with vitrified brick. Structure byilt for

t»nce on Simplra concrete piles.

<.iut«vitle» Ky., Northwestern a<»wer, Section Bl. Contract Ko>, 63, IftlO,

rcixl, Chief Eng. Horse-shoo almpe, 13 ft. 0 in. X 0 ft. equivalent to ll-ft. 34n.

wnf. An tmnaverae Imrs Jt/lin, square 9 in. e. to c; longiludinal bars 3/4 in.

tu. ICicavation mainly In sand and gravel with aome yellow clay.

Louiaville, Ky., Northwt'atem Sewer, Section B2. Contract No. 64. 1910»

Chief Eng. Horae-nhoe section, 9X9 ft Transverse reinforcing biy^,

12 in rm cnntcra: longitudinal ttael bara, b/H in. square, spaced as ahown.

' Uy and Band. Average cover about 13 ft.

>,^Borough uf tile Broni. New York City. Horae-ahoe ahai>vd, 8 ft. 0 in. X 0

• in,; very hvavy construction for aoft foundation. Transverae arch bars, li/4 in.

*i'ifcrr iUln. c, |o e ; traoaverae invert bars, 1-1/8 in. square, 10 in. g. to c, ; longitudinal bars

^*nii, 1/2 in., 12 Itt. c. to c; longitudinal bars in fouudation over piles, 1/2 in. square, G

'->' reinforce m««nt in ifinorete caps over piles, 5/8 in. bars.

fir«lfurd, Ma«s„ Outfnil Sewer, 1012. Wm. F. Williams, City Eng.

: ft, 8 in. X 7 ft. Right half, construction for 2 to 8 ft. cover; left

tor more aevere loading. Reinforcement for right half: transverse

I til round, G- 1/1 to 7-1/2 in. e. toe, depending on depth of fill: extradoa

ifi. rnand* h-l/2 to S-'ll in. c. to c; interior side wall and invert bars, 5/8 in. round

' to 16 in. c- to c. ; longitudinal bars 1/2 in. square twisted. 12 in. c, to c. MaU*rtals

' fiKHi of snwer; 37.3 cu. ft concrete, S4 lb. reinforcing bars, for cover from 2 to 5

j^A& 111 fnr ftover from 5 to S ft Reinforcing for left half; Iramivcrw intrados

M c. tjoc; tranav<*rae extrados barn, ll,'4 in. round, 12 in. c, t*i c,;

!). i^mnd, 8-1/* ii» 10 in. e. to e,; interior invert bars, 5/8 tn round

■ .M i<^K-. , ^v'.-uor invert and aido-wall bars, 5/8 in, round 6-3/4 in. c. to c; longi-

rfiBiM

440

AMERICAN SEWERAGE PRACTICE

m '

- c

Z Banh^

(C- +^ . ' ' T^ ■ ■: ■ I ■■■; ' •'

Ntfw Bedford.

-e-
Bron X .

Fig. 162. — IVpical horseshoe sections.

\-V2 .\\fSRr.i.\' i&^I^SOE ?RArT?:E

■ .rtinaj I'M-* . ^ .n wiiiArf* ■ jr-^ttfi. ^Lit*Ttiu i»*r IxifArfoijr u 4pwv*r. >%.rTi -x. :>. ?niirr**p:
•I, .'. i, •; -.-.ni.tr^n* 4twH.

' .; 'V..rt -P'iilaj>frjnia. I**.. T ■.r-»»^iiup ■J:T»»r»»^ -r-ir*«r •nmiiur. S»mi-»iliptira4 «er*i.in.

y .; I'*'-»i> — ■^'— Tj'TLt^ ." V . ".r.un I irt-r-^irin* •"•¥'-r 1!»'.«k ~L«xa Z* 3iiiar-«.
"ii**? .~.nir. «>nii-":ii.i'ii'.ii <pf—ii-.n. T r. '-; ? .n. ' 7 -. ' n

.'.J Litur — •' i.r^;<.;l \.7iiK«i.ii-. jiiuir.i si V^rer *'ipni- N--v V ir* "Ir-.- ".'Ml*. ; "^uiiij
J-' irn. '',■■'.1**^ /-riB. ■ip-ni-»:iin».''ri. — ;»'- '.T -. -i .n. < 17 -. "ar. .ni'^r* •niterr-u'nun Ji

■l'^n^c■'nPTl^

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r. 'ir. i 2'' ir.. «• to '^ La tavrt.

S- ' .i- iT'ilir o'-»r.Tpr.= fcw-r. 11 ft
• \r'. .". •* ;r. . l«»in r. t.. p : irj.rj»v*-r«p
1.! Vnr*. 1 2ia . lOia. c t. r ; ii.r.olu-

: ] .r.jT.' ;::ri.il Jiars over pilp». 5, > in ,

- •,*. ;>!.• -» in p.-iph b^nt '< •» in. Piip*

r.« ri •.*!'.• r -i-lf; b^ct.^ jipacp-! 3 ft ti

T'z'i- Am .<■.: C. E.. v.. I Ixxvi. iyi3.

/., I'.P, W,....i-.;f ,',, I;. :,Air. , f'l. rr.'.'.f"- liur. S^-a't. 1^)3. T. ChalkU-y Hattoa.
f ',f ■•■,', Uf'^ i.i.v. S* rrii- jp'-ji if -«wt-r 10 ft. /[ '> ft. »» in., finfi.rr-t-d with woven mire inr«h

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EXAMPLES OF SBWBH SECTIONS

443

— — 2/ '6"

St. Loul*. Chicago.

Fi 0 . 1 ♦i'J , — ^lypical «enii-€ur ular scet ions.

444

AMERICAN SEWERAGE FRACTICE

mud No. S eifNiaded metAl. Invert Lined wilb one coureo of t>Hck. Vuntcipoi Bnginmtrin^ ^
October. 1904.

Fia. 164c.— Borougb of Brooklyn, New York City, 1913, E. J, Foft,Clii*f En«.,8*inl»
circular section, 8 ft, 4 in. X 5 ft. 8 in., equivak'nl to T^-ln. rirRulnr accUon. Tttbl«» 140 fft'rwfl J
1i coinpArtaon of the hydraulic propt?rtii?9 of the »r> mi-circular section &od of & 7^ixi. cijrfiulaffj
ovcdon. both at the nuudmum capacity of the ocelion.

T.vBLE 140. ^Comparison of Semi-cihcui^ah akd CiitrtTi*Aii Ssmoyg

Beet ion

Aroft.

•a. ft.

wetted 1 Hydrjiulic Di«ch&rce

pertnictcri radius. i — 0.00 1

ft, ft «u, ft , m^

Semi-circular.

Circnlnr. ,

32 94

32 35

18 20 1 hSl ! 151,31
17 20 I 03 ' 156 25

Fig. 164d— Boston, Mass., Kemp St. overflow, 1912. E 8. Dorr, Chi*f Ea« SenU^
circular sectaon. 10 ft. 3-7/8 In. X 0 ft. 3 in. Tfnosvcrvc t)t«el reinforoement, a/ito. tMr* '
B in. c. to 0.

Fig. 1&4«. — 8t. Ixiuis, Mo., Hnrleni Cre«k Sewer, 1908, H. F. Fardwell, 8ewtr Commit
doner. 8cmi-cireuUr section, 29 ft. X 18 ft, 7-1/2 in., to curry 15-ft. fill over arcli and %hm ^
lit^ftvicst railroad loading combined with 7-ft. tilK Strcwies in various aoctiooi dei«rtiiifi«i| ^
from analysis of ciroui4iT ribn with ftxed ends given in Prof. CborleA E. Greened "Tnun
and Arohes.** Reinforcetnont, J ohnunn corrugated ban* 7/S in. for transverso and 1/2 In*]
for longitudinal reioforcemcnl. Intriuios transverae bars apaood 10 in. e. to c. There w«ra
also intermediate 1/2'io. tranaverae bars in side walls and batuioh of ardi running to point
0 ft, &*l/2 in. from top of side wall, alternately with 7/8*in. arch bars, making tpaciag of
st^el in aide wall and haunch of arch, 5 in. c, to c, Extrados bars, 10 In. c. to «* Aft^h
(iftrried through to rock and looeto joint left between side wall and invert. In earth. Motion
considerably widened at base, invert much thicker and reinforoed to diatribute thrust of
aroh over greater area. Eng. Record, Doc, 14, 1907.

Fig, 104/,— Chicago, III., Sanitary EHstrict. South 53d Ave. acwcr, I9M, Geo. M. Wiancr, ,
Chief Eng. Horse-shoe section, 16 ft. X 12 ft. 3 in. Dividing wall is to provide high velort-
tiea and avoid deposits by keeping dry-a'CAther flow on one aide of the wall. Stop ptank« J
at head of section divert flow to either side of dividing waU. Owing lo soft ground, Invvrt |
reLuforce<l throughout entire length; upper transverse barn 1/2 in. round, 6 in. c. to c; lonkwt
transverse bars 3/4 in. round, 12 in. c. to c, Undef railroad, arch reinforcfHl with 'Jl/4Axu
rods 6 in. on centers. Dividing wall reinforced with two rows of l/Tria, vertical ban t^ in. tm
centers and 10 rows of 1/2-in. longitudinal bars 12 in. on contera. Joint betwetm divi<Ung
wall and invert strengthened by two acts of bars ben tat right angles. Height of wall abova
invert, 4 ft. 11 in.: wall slightly off center, Efigineerino and ContraHing, Feb. 11. 10 14.

Fig. Hiha—Si. Louia, Mo., South Uartem Joint District Sewer, IWiif. Horse-shoo section,
12 ft. X 9 ft. 7-1/4 in. Left half, section in rock cut; right half,aectian for earth. Arcbd^
signed for 20 ft. cover. Reinforoemcnt; 5/8-in. transverse arch bars. 12 in. c, to c.: S/84n»
intermediate side-wall bars near interior, running to point 2 ft, nbove springing line of arch« ]
between aroh bars; 5/8-in, transverse invert bars in earth ftection. 12 in. c. to o. : l/^-in longi*
tudinal bars, apaced as shown. In earth materials per linear foot wore: eouerete, 2.«Jt '
eu. yd.; vitriBe<l brieki0.l74 cu. yd. : Iranavene reinforcement, 90.2 tin. ft. 5/8-in. bars; longi-
tudinal reinforcement. 22 lin. ft. 1/2-in. bars, For section in rock. inat4*rials were: eon-
crcto. 1.92 cu, yd.; vitrified brick, 0.174 cu. yd.; Iranavemu eieel, 73.7 Im. It. £/B4a. baiai
longitudinal steel, 19,0 lin. ft. l/24n. bars.

Fig. 1056. — Bt, Louis. Mo.. Dale Ave. Sewer. 1010. Hcctangular teetion, 0 ft. 3 In. X ft
ft. Types were designed to meet throe oonditiona. In ftrst, nalural rock surface waa at or
above akowback of flat nrch, which had to earry whole lorui directly to r»<'i^ 'I ^"- ''•' ^'<
concrete walla were merely to smooth up :iidrs of cut. In m:votnl csm*. r
below skewhack and IH-in. concrete wall* UAed. In thinl nnmn, rock wa*
hclow springing line; sec tiieht half of figure. The l.H-in. waUs, reinforced by l-tc
12 in, on centers, were dettgned as bcaius to carry arch ihrutt ^t t)T>pf*r **ftd •tiid f»st ^
[ lbi«low. As mmwvr was largely in rock, the narrow, high r' '
|V«ost economical. Owing to depth at which scwrr was I

i mdlt onwb moro thao offaat locfeaaod dopih. t. ^'w . ^« t>i. u, m i

tM

EXAMPLES OF SEWER SECTIONS

445

'^i^}.

"r'

446

AMERICAN SEWERAGE PRACTICE

Fis. 165er,— St. Loub. Mo.. Eadrn Pnbiie Sewvr. Flrat S«etMia« 1010.
or Mrmt-cltiptirjkl lu-fsh mctioo, 1% ft. X IS fL 1-^/8 in. f^t hmlf, oonstmetiofi tit rmik *
Tiiht h&Lf, type for ei^nh cut. TtftOfvvrae estfrndo* reinforeinc ban. 3/4 ia. •quftn» 19
e. io c, tmuvefie inlndoM bftre, | vq. id., 20 ia, e. to c. W. W. Horner itetat lii«t «^ai
thii type ixivtcad of that •bowna in Fi«. 165a, hsa b«efi & m&tter of judcmnt io
p&niculjir cmm. The fiir«-fleiit«r«d ar«b lu« been prefeirnl vberv loadias i
miifona etkith losd.

Fi^' IfiM.—St- Louifl, Mo. fforM^-«ho« •prtion. le fl 6 in, X 141 ft. e in. Left
OOOrtruclion where rock wjui encoiizit<»r«d nbovc apriiuEinc line: richt httlf. eoo«trairtio&
•*rib cui. Areh deBigned to e«rry 25 ft. fill &boYe crown. HcinJorcvment; Inn
ioitttdoi uid extrndos bnra for ri^ht hoii. 3/i in. t^uare, 10 in. on e«ote»; for lell
trAnfverM extmdotbftrs Sf% in. ftquam, 10 in. on ocnieni; trmaorwae inrort bttn, 3/4
square, 5 in, on centers; upper trantvt^ne invert bAra extend to point 2 ft, belov epriiicK- :
line of &rrh. Lonxitudinnl bars 3/4 in. 0«]ujbre. sp«««d ne ifaown, except two ban •( tm^
ftngle of inv«t and aide w«Ib, whicb wer«i 1-1/4 in. round.

Fiif, lOAa.— HArriiburc, Pa.. Paxton Crerk InUt^i^jiting, S««n<r, 1003, Jam«« TL Fue
Consultinc Eac. ParaboUe •action, OX 5 f t. ; el*o imaller section of aaiae t>i>c» 5 ft. 1-1 .^
in, X 3 fl. 9 in.* with iunc UuckooM of masonry. Sewer croiiai iwftinp and i

-a-

Harrt^bun^

Fio. 1G6* — Tj'pical parabolic or delta sections.

mainly. Probably firwl parabolic eectlon in this counto% R''infort?«rmcnt, ^nn*"
10 expanded meUil, L>oad<Kl poal train w&a denvilrd on aldijis dirrntJy cnr*t anni^r
wittiin 2 wcvka aft4?r completion withaut injurinii: it. Backfill very wvl clay, top of i
about 5 ft. betow tr&ck. At otber potuta no ill otfe^^ts reeitltad from praMurv ol JOMtl. ^
wet backfill. Eng. Rtcord, Oct. 15. KH>4.

Fig, lrt66.— LcmievUle, Ky.. Happy Ht»llow Sewur. Contraet 1* 1W>7, J. &. F. Br
Chief Enc Parabolic ivction. 8 ft. «t in. X 7 ft. 4 in,, buUt in sballow cut, in |
than half the nower being above natural nurfaee of eround. Excavatinn in loam and rl«jr.
Saoiion eonsEdered eepeeiatly advuitaK<H}ua for condttiuna, on a«><^ount of ef'onoray ol i

forccfni^nt, 1 2-ta- I

^ shown, approxinsataly

r

ItJOO, J. B, F- BtMd.
n alluvial rlay rvqolrifa^

ia ombAnkmrnt •ertion, and aironic arch afforded, Tn.
12 bu OD ceittrrs; loDjdtudinal rc-inforfcrfjienl, 1 ''2-in hn
12 In. on <^ontera. Sewer may he eov«rvd by fill of 30

Fig. I07a,— 'Bwirp-aaa Creek Drain. Section A* C'
Chief Ent. RcctanituUr aoction, « ft. X 4 ft. 0 ift* cor

foundation of oak pil«ii driven in l>enU of three, irpaccd 3 ft. 2 in. e to c. Tnuuvim*
rrlnforwTDifnt in Hat r«x»f. 1 2 in. eauare ban, d in- on Mrofcrn; rvmaind«r ot trati«vn
inoldc walU and tnv»trt. l-tn »<iuarcbura. 9 In. on <^c<>nten: Innsitndinal rr^
wtoarQ bam irpar««d appraximately 1^) in. on c«90len lonttitudioal rvlnl«>
pile, 1/2 in. »*|uarc bare.

Fig. 1071-.— fiarrinburiE, Pa., Suiiuehaana River int^m^trttinft ««wi»r, 1012, Jai
Fuert««, Conaiiltinc En»- lleeUncuUr eoetion, 3 f f '^ ' ■' *- i rt 0 tn., relnforeed tfai

EXAMPLES OF SEWER SECTIONS

447

Louisvtlle.

Marrisburg

1) III III

-e- -t-

BPOoKlyn. Hoboken.

Fig. 167. — Typical rectangular sections.

448

AMERICAN 8EWBRAGS PRACTICE

with 1/2 in. •qumre ban, 7 in. on eentera. ezeept where aewer waa <m roek bottom,
reinforcement in invert waa omitted. Rectangular aectitm chosen oa aeeoont of
of Mwer to surface of ground. Enff. Record, Feb. 24, 1912.

Fig. 167c.— Ogden, Utoh. 1907, A. F. Parker, City Eng. Rectangular condmt, 3 ft.
X 2 ft. 7-7/8 in., with top practically at surface of ground in street
so that gutter and curb forms part of conduit. Under street crossings
reduced in height to 16-1/8 in. and the top curved in form of arch like invert. Roof
forced with {-in. rods, 8 in. on centers; side walls reinforced with 3/8-in. rods 16 i
centers. Eng. Record, Jan. 18, 1908.

Fig. 167d. — Des Moines la.. IngersoU Run Sewer, 1905, John W. Budd, City
tangular section. 10 ft. X 5 ft. is selected on account of proximity of grade line of
street surface. Transverse steel in flat roof, 1/2-in. corrugated bars 24 in. on centers •
invert, 1/2-in. corrugated bars 12 in. on centers. Longitudinal bars, 1/2-in. square,
as shown. Eng. Record, April 28. 1906.

Fig. 167e. — Borough of Brooklyn, New York City, 1913. E. J. Fort, Chief Eng.
tangular section 10 ft. X 6 ft. 8 in., approximatdy equivalent to 102-in. cireular
Table 141 compares the hydraulic properties of the rectangular section filled to within 12
of the crown, with the properties of a 102-in. circular sewer.

Table 141. — Comparison of Hydraulic Properties of RECTAyoui^A '^^
AND Circular Sections.

Section

Wetted
area,
sq.ft.

Wetted

perimeter,

feet

Hydraulic
radius,
feet

Discharge itm.
cu. ft., sec-
s - 0.001 __.

10 ft. X 6 ft. 8 in.j
rectangular. | 49.12
102 in. circular 1 55.43

18.55
22.51

2.65
2.4)

294.60 i

319.64 ^

Fig. 167/.— Hoboken. N. J., 1913. James H. Fuertes, Consulting Eng. ReetanfoUr^
sectioQ, 7 ft. X 4 ft. 0 in. , is of particular interest on account of V-shaped waterway provided
for low flows. RectAHKular section with flat top selected on account of lack of head room
between surface of ground and top of sewer. Sewer in soft foundation has timber platform
of 4-in. planks on 10 X 12-in. utringcrs on 3 X 8-in. caps, two to each pile bent. Piles spaced
3 ft. 8 in. c. to c, 3 pilos to a bent. Roof reinforced with 5/8-in. bars 10 in. c. to c.

Fia. lOSa. — Lanc.iHtcr, Pa., 1903, Samuel M. Gray, Eng. Semi-circular. 12 X ft-ft.,
section ^ith 24-in. half-round dry-wcathor flow channel or ** cunette." Two types designed,
one with concrete arch reinforced with 3-in. mesh No. 10 expanded metal, and the other
with an arch of fuur rings of brickwork.

Fio. l«Sfe.— Louisville, Ky., Southern Outfall Sewer, Section A. Contract 6, 1908,
J. H. F. Brc<*d, Chief Eng. Ilorsc-shoc section, 8 ft. wide with 3-ft. half-round cunette.
TranHvcrse iutradoH arch bars and side wall bars, 5/8-in. square, 12 in. on centers; eztrados
arch bars and exterior Bide wall bars, l/2-in., 12 in. on centers; upper and lower transverse
invert bars, )-in. square, 12 in. on centers: longitudinal bars, 5/8-in. square; spaced as shown.
StTtion on incjinu of about 30 deg. to horisontal, and cunette used to confine dry-weather
flow on account of high velocity. Invert of cunette lined with 30-in. vitrified clay
channel j)ipe.

FUi. lOSr. — Wjiahington, D. C, New Jersey Ave.. Trunk Sewer, 1902, designed in ofliee
of Kngineer Comininsionerof District of Columbia. Senu-circular, 18 X 10-ft- section with
9-ft. half-round cunette.

Fitj. U\M. — Brussels, Belgium, Maelbeek Creek Storm-water Sewer, 1895. Horse-shce
shape, 14 ft. 9-1 /2-in. X 12 ft. 1-1 /4-in., with 0 ft. 8 in. wide cunette. Interior of sewer lined
with 1 /4-in. oetnent jiiaster and exterior covered with 3/4-in. coating of cement mortar. Bng.
\fws. Mar. 20, ISOO.

Fit;. lOS*".— Syracuse, N. Y., Harbor Brook Intercepting Sewer, 1912, Qlenn D, Holmes,
Chief Eng. U-.sh:iiM*d 3()-in. section. Left half, construction in firm material, right-half
section on i)ile foundation. Flat slaV) top built separately and set in place, joints be-
ing filled with mortar. Slab 12 in. wide reinforced with 3/S-in. square bars 6 in. on centers.

A sewer of practically same design 3 ft. wide at top was constructed in Lynn, Masa., in

EXAMPLES OF SEWER SECTIONS

449

I

^^6--~- V>j ',3' •..

l< - J'2" ^,

Ri chmond.

29

Syracuse.
FiQ. 168. — Cunette and U-shaped sewer sections,

450

AMERICAN SEW EH AGE PRACTICE

SaltUkeQty.
(A(^ueduct)

#

^
^

1/6(7'- it

Philadelphio .

FT

ia4^

f0 4'

B o & t- o r-i

i I u. 1 09. — Typiciil rcctonguin t »ct « )ua».

- of C. H. Dodd. Chief DrnftsmAn* Bomun Sewer Department, who aIao
«lnB*^ ot^ctioD 2 ft. wide on top (or Bfwton in 10l>8.

f**,. . , iioroujth of Hichmond. New York City, Diatriot CA Trunk Sower, 1907»

L«»u&a L TrlbuB, Couu-. of Public Worka. U-4tuiped 6 ft 6 In. semi-circuUr Bection. Sidu

wntl* r«iii*tirc«d with No, 10 cxpnndvd metal »nd d&t slab roof reltifor«^ with 3/4-in, old

JrJtnwon bATu fV in, on centers tmnx^^crflely and 18 in. loD^itudinaUy. General sur-

«jf land UHow top of •i^w<?r. Shq. Recmd^ Nov. 2, 1907,

/'m. I «•;»«- -^SaU L*kfl City. Bitt Cottonwood water conduit, 1007, L, C. Keliey, City

m.' iU»ct*nirulftr a<*ciion, 3 ft. 5 in. X 4 ft, 5-l/2-in» Fi^uro ihows conitniction in fill;

r amnion uncd in exravntion. except reinforcinpt bars were plaecKi nenrer interior. In

, Mnetion resemhle'd thai shown but luaked reinforcement. Engineering and

tiino * ■ '- If 108.

. Ifld' i phU« Pa,, Devereaux St. Sewer, 1000, Geo, S. Webiter, Chief Eng, f^o-

ooirtrh i I il through low land on 2-1/2 X5-ft. piera ap«c«d 1^ f t c, tor. Inn^tud*

%ll^ and 11 ft. i> ID. apart tranirveraely. Beworprotectodby embank men t with 3 ft. cover,

■'Wrranw rtnnforcement of flat slab top. 1 in. aciuaro bam 6 in, o. to c. ; both ends uf every

rod bent tip at *n &n£lc of 30deg, 2 ft. 0 in. from either end: side- wall bars. S/H-in.,

e. 0 in. e to e. ; tmni verse invert bars, 7 /&-io. aquare. 6 in. o. to c. Longitudinal bart in

" '^-i«. iquiire, approximately 18 in* c. to c: longitudinal bars in invert,

f (^-in, PI I iteither end over piera they were 1 in. aauare, 6 in- c, to e. Between

and i:»'^ ^- i^ (liree vertieal dowels 1 in, square, 12 in. c. to o. Roof pitched 2 in.

\ eenter to uutaide, plastered with 1-in. cement mortar.

100^,^11 OS ton, MusB., Bouth End Hewer Improvement, Section 2, Union Park St.,

t3(* E, & Dorr, Chief Eng. Double conduit rectangular aeetioni, 6 ft. A in. X 6 ft. b in.,

O ft 6 in. X 4 ft. 2 in. Double structure required by limited ipaee for construction

ooDduita. Transverse bars^ 7/d^in., 12 in. c, to c.; longitudinal bars, 1/2-in., spaced

• bowo« Section «ontfiructed on platform of 2-ln. plank laid on 3 X 4^in. aills.

r ^itf, \t^l. — Boston, ^tH8al,1 South End flcwer Improvement, Siwtion 4, Albany St.;
^*3; R. !< Dorr* Chirl Eng* Gravity sower, A ft. 10 in, X 10 ft. ft In.; force main 2 ft. 9
X 10 fL A in., rectongular seotion^, double conduit. 8eclion constructed on 4-in.
• on ft X 8^ln. Qaps cm three-pile bents. Transverse reinforcement, 7/H-in. rods*
I 34 in. OQ osalen in upper roof, lower invert and vertically in division wall; other
Wwf^s^u 12 in. Of] eenU>rs, Longitudinal reinforcement, 1/2-in. rods spaced as shown. Sec-
^oft shown Utnita to which (t is aoraetimee oecpasary to go where space is very much

^^, tttOr. — Boston, Mass., Stony Brook Channel. 1906. E. 8. Dorr. Chief Eng. Double
**^^^i<QDt 9 ft, 8 in. X 10 it, (t in., ooastruoted to replace old stone masonry channel, and on
^'^^i^ %eooimi work involved spcyi-ial difficultica. Section with I-beams in roof used that back-
^"■*H might be placed more quickly thun on section reinforced with bara. Left half, rein-
y'^'^^ciimt in roof, 1/2-in, bars forming a truM unit spaced 5 in, o. to C* Right half, 10-in.
"""••ma LCi roof spaced 4 ft. on eeut^<r4. with 2-in, Kahn rib metal stretched between these
«'-Q<saL^m» and lower Aang«s of I-b«aniN wrapped with Kahn rib lathing. Side wall bars,
«/4»b|^^ t|iaced 12 in e. to o., invert bars, 3/44xu, spaced 8 in. c. to o. Thia type laid on
*»**tloftn of Ha. boards on 2 X 3-in. silla.

^<^ l?Oa — Bor«t*gh of the Bronx, New York City, Broadway Outfall Sewer, 002,

I r^,, C K, Graham. Engineer of Sewers. Twin semt-c^ircular sectioAi

I , constructed largely above ground, twin sectiou betug arlopted as r«-

^'^^f''' than single* large circular sewer. Depth of cover to surface of

V I' i-tcd on concrete, timber, rubble or pile foundations, depending

_'-l - h^ra Li- 1 juL Erig, &*ttird. Nov, 11, 1905,

9*0. ITTi^— Borough of the Branx, New York City. Rectangular twin section 10 ft. t^ in

* S It^lO m. Reinforoement: transverse roof bars, 1 in., 0 in. oenters: vertical bars In
, l-l/H4n,, % in. o. to e. ; vertical baraln division wall, l/2*ln., 7-1/2 in. o. to c.j

frifvvert Hnrs, 0/Mti,, 0 in. e, to c ; longitudinal bara in roof and walla, 1/2-In,,

. iiudinal bart in concrete over pilea. 5/8-in., G in a, to e.« tranvenm

^* ^ in, PiloB spaced 3 ft. 3 in. c. to u.; 8 vertical piles to bent with two

*•**• ttcr 4ide Tran« Am. Soc, C.B., vol Ixxvi, lOia. plate Ixiv.

/ I. of BrTKjklyn. Now Vork City. 1913. E, J Fort. Chief Eng. Twin

., 1 1 ft- 2 In. X l^^t hf% in., approximately ettuivalont to 13 ft. circular

^oviof eomplotfly fuU, rectangular sectioo estimated to ilUoharge 906*80 <M. H

452

AMERICAN SEWERAGE PRACTICE

— .*>.«.. ,»:.^.-j—

^

yfy j ■ ^<:>.:.■■y:'''■<>i:':':::'i.■:.^J<'^■■

< ]$":>

V-

I I

fTo^^,.\ ■ /vTTne P

—»---£--:*•,-•% v^-.T'

'''•'■;v^'''-

^

- C -

B roo K \ y m

Fnj. 170. — Typical double sections.

EXAMPLES OF SEWER SECTWm

453

ciroulttr sewer 90S.01 mi ft* out el slop* of 0 001, Twin rectangul >
tml mmcimiim How Line. tiUowing f^in. «ir ttpuve nl tc»p of each efaaam L
afgpa Apt>ru»irfuiiely I037.&3 cu. ft, per JMioood^ mi n«nin«4i 080.H6 cu. ft. per «cnonil, the
niim of UiK Ki-ft rlrfntlttr sdWf^r. TKorc i» material ttavin^ in bnftd room with tho twin
^ulur «oetiori ov«r the i^quivuknt eiruulttr mi'ciicjn.
l71.L^Rorougb of Brouklyn. Mf.w York City. 04th Si. Dutlafl S«wer, IftOl, H. K
r ling. Triplr* rt^r^f^iniiuUr section, 7 ft. 6 ta. X 8 ftl 10 in,
!'K)r(}URh of the Brotix. Nr*w York City, Tri;*lo aomror, am" 12 X 0-ft, i«ni
^»' . riifti^ngulAr •cKtlioas. rcinfnroi^d uo foltowtf; Tratuivonie atoel burs in fi«tt
I l*iBL, 8 ill. c. io 0.; v«rtioal hara in outdiile walls, 1 1/H*in,« 8 iin. o. Ui c. ; vertical baxa

• ■j.^^i^^j^i'LksiZ^^i^il^lLi:;:- ■■ijLVs.iAi--fk;^'-.;i l-^^:..|i. J.>^-T^^t-»*■^i' 'Vi tiij[i''' '(I'^^M

-^-^— :>^V:

'^ir

rrf^

t.f

t.*

Fui. I7L

B ron X .
-Typical triplo sections

v\

I w»ib, l/2-in.. H tn. c t<j «.; trnnnv^rw invert ban, 3/4<in., 8 Iti, q» Io «. :
I hmt%. \rMi\ nim< I'd m ihown: loniutULiiDuI bin* in invnri over pUira 5/H-in,» 0
' («4l on iiimU with It vnrtiriJ iiud two hr»fM(« p]|i*a OACht benUi
M •rit»r»i'tti urf^uriiil piluH <|nfHroit.c4~| ou 2*iii. plank piiiifonu.

*^-'*' "* ^■''- Trunk S4«w<<r nnrl H^'ftfirruM Creek

iu«'( Entf. Conjpouiid •tnj*'tur«* lu-
ifiiltV y 4-(t, ^'^in rcctnnculnr drain,
I <>> au mr npAfx* or clinu^ki.^r lU'lACivit p4)HUioniii of nhnnn^U du*; to lowd>i»«fm«
I «4l requirlrat » pil*? /tmnanlinti, »n(l tUn Fo«ultiu< ««tJtiotuy iti uiun« oni* •ml of

454

AMERICAN SEWERAGE PRACTICE

Fio. 172. — Compound sewer section, Louisville.

FiQ. 173. — Millbrook intercepter, Worcester.

EXAMPLES OF SEWER SECTIONS

455

Pileo spftced 3 ft, 2 in. o. to e tranereraely, three pUea ta benL
wmwT towjtrd opposite ^ndsi acwor tvnd dr^n wan separated at upper end
hnr, which gradually increuaed, due to increasing difl^exMioe in etcviittotitt
Materiftl escarated almost wholly uHuvial clay, B«q(« 3 ft. c. to c,
Lfour operaiioQB, invert of di^in first* after vrbich the ddo walls and top of
utructt<>d. Folio wiriB the ooraptetion of tho drain the »ide walla of the air
the wwef and the drain and the invert of lhr> wfrwer wr*n' built aa u third
the completion of which the concrete was placed in the arch of thp aowf-r.
linforoemunt in tbe^ udrlc walUi was 3/4-in, bars spaood 9 in. on centers, 'the
» tranevcrao rc'inforccMncnt eonsiAtcd of half-inch bars 9 in. on crnters.
bar* irere half inch, spaced as showii. Ovur each pilo bent ther« were
|ui»vene ban, spaced 4 io. c. to c.

roBBtCT, Ma«„ MiUbrook Intcpceptinit Sowor, 1897, Frwierick A. MoClure,
lArg«r motion i^i old trunk sower cnnfitructed in 1^80 of quarried stono
laitl throui^h ledge nnd occupying: ao much of street that it wna di^eincd
paraUfl it with interoeptRra. Acoordinjcly conduit was df^siKne^d to ac-
^^ftwago innide larKQ sewer. The brick section was constructed inside
^^^Bfrpth of flow in main sewer during coDstruction about 3 ft. See
immoteadcat of Sowers* Worcester. 1899.

CTION OF MATERIALS OF CONSTRUCTION

for Arches* — In the older sewerage systeiiLS will be found
large sewer arches coiLstructt^d of stone blot^ks, An
Ig. 173, a section of the MUlbrook conduit in Worcester,
reason for choosing stone blocks was their availability
It m compared with brickwork for large arches, and further,
rheii such sewers were constructed, concrete and reinforced
p used little, if at all. Even more recentlj^, rubble masonry
d to a considerable extent, especially in Philadelphia, on
I relative economy- Its use has, however, b^en largely for
md masonry below the springing line. Btone blocks have
^!tically superseded by other materials for sewer arches,
^e arches have fewer joints it is more difficult to obtain
^nd consequently the leakage is apt to be larger than wheii
Us are used,

>nry is still used to a great extent for sewer arches, princi-
lint of its economy in certain cases nnd the ease with which
y can be handled in tunnels and restricted places. Brick
( ti* their greater number of joints, are more liable to settle-
Jii nd unless special means are employed in bonding

|ff ii of the structure may be more uncertain.

tnictaon of brick arches, three general types of bonding
\Qd, In the first, the arch is built of concentric rings of
bricks laid as stretchers; this is sometimes called **row-
In the ge(*ond type the brick are laid part as stretchers and
lers, a^ in ordinary l>rick-wall construction, with radial
th the outer end of the joint is thickened by increasing the
ihe moftar or by insertion of thin pieces of slate. In the

456

AMEBWAN SEWERAGE PRACTICE

third method the masonry 18 divided mtoblockd or sections, Figs, ISS
161c- and 163rf.

Plain concrete arches have been used to a coii ' nt m

recent years, and have an advantage over the ston lvoutt

arches in that the structure is somewhat more elastic and may withsUrid
tensile stresses to a slight degree although they should not ^• ^ - '
with this in view. In the design of such arches, &s wi*ll
stone and brick, the line of pressure should fall withi r
the section, in order that no tensile stresses may In
the loads acting on the sewer were kno^Ti exactly, it would bo jiossiH
to design the section so that at no time would the line of prtmtin I
outside the middle third, but practically this \b impossible. a« €nir knoi
edge of the action of earth pressure is a matter of appr
On that account, under special conditions the stresses in i. . . 'Ui

may not be entirely due to direct compression, but in addition bendiiii:
stresses may be developed.

Arches of reinforced concrete are not subject to the limitAtioM jtwt
mentioned, but can be made to withstand heavy bending moraents ij
reinforcing the section with steel bars to carr>' tensile stresses. la
arches in which the line of pressure lies within the middle tMrd, Ui5
stresses in the arch are mainly due to compression and the coticrete mini
of necessity carr>^ the principal part of the load, so that the steel canaiH
be stressed to the allowable limit. On the other hand, the pte$mce d
the steel reinforcement is of considerable value. Concrete i« ©ore
reliable in comi^ression than in tension, and on that account the sitd
f uridshea a sort of insurance to the structure, to care for
which may occur on accoimt of unequal settlement of t J
temperature changes and many other conditions, of which the dc«i|3itt
can have little knowledge. The steel is also an additions' ' * ' '
safety against careless aud defective construction. On acr
presence, it is possible to increase slightly the allowable wvMki u --
ill the concrete over those which should be used for pimn • i
masonry. Because of these considerations the authors believe tl'
large sewer arches reinforced concrete offers greater advaiit
plain concrete, even though an analysis of the section shows
line of resistance for the conditioiis considered will remain
middle third of the masonry section. An inspection of the ftoal)')
given in the following chapter will show how great a cluuii^e n»T
occur in the theoretical location of the line of resistance due to s cfaftfif?
in the assumed conditions.

Electrolysis in Concrete. — Considerable study has been given rwwiitlT
to the corrosive effect of stray electric currents in concrete reinfflircfd
with steel. For a careful discussion of this subject, the rvAder »
referred to "Technologic Paper N * if the Btireau of 8taiuUrdi|

?ve th
EitaiM|||HJ

he ULuaiyJ^

Yiti, 174. — Brick fnjm nrrh and invert of Worcester sewer.

Fia. 175. — Brick from side of invert of Worcester sewer.

lFaHn(f pf9fft 450)

Fio. 176. — Brick fruiii invert of Worcester sewer*

Fig. 177. — Brick foraung manhole ledge.

(TiiabvavF^

EXAMPLES OF SEWER SECTIONS

457

J. S, D<?partment of Commerce, which also contains a bibliography of
the 8uF>jeot.
Wear on Sewer Inverts. — A careful inspection made in 11)C)1>-10 of the

findition of the brick sewers in Worcester, Mass., by the authors
rveloped a number of interesting points. Manj^ of these old brick
wers forming a part, of a combined system of sewerage and varying
in size from a 24 X 36-in, to a 48 X 724n. egg-«haped sertion, were
fciistructetl between 1867 and 18S0. Natural or Rosehdale cement
fPfts used in nearly ever>' case, and tbe majority of the sewera were built
by contract.

I The brick invert wa^ foimd to be badly worn in all aectiona where the
locity fio\\ing two-thirds full (Kutter's formula n = 0.015) exceeded
^r 9 ft. per second. In some sections where the estimated velocity
lounted to 12 or 13 ft, per second the first course of brick in the invert
in places was worn through and the second course was partly worn.
A majoriiy of the streets are surfaced with gravel and during storms a
Lirge amount of street detritus washes into the sewers in spitu of the
many catch-basins. The effect of the sconrhig action of this material
M it is swept or rolled along by the sewage can be seen on the brick
Hbieh, especially below the dry weather flow Une, were worn to smooth
w:e9 and rounded edges.

On slopes where the wear has been excessive it was quite generally
true that the upstream ends of the brick were worn away more than
Mp downstream emis. Figs 174 and 175 show brick from sewers at
Worcester, Mass. The two in Fig. 174 were taken from a 30 X 45-in.
^H-sbaped section built by contract in 1874. The masonry of this
|Krer was constructed of two rings of sand-struck brick of 20 to 30 per
cent, absorption, ;by volume, laid in Rosendalc cement mortar. The
^liown were taken from a section where the grade is 0.0694. The
ty io this section, based on Kutter's formula, n = 0.015, at two-
thirds full, is 22 ft. per secoinL The left brick was taken from •the
of tlie arch, on which there was no wear* The right brick was
ken from the invert, the small end being the upstream end. The depth
I whieh the mortar joints were washed out can be seen on the worn
fck by the change in shade from dark to light, the hght shade being
sed by part of the mortar joint sticking to the brick* Tlie mortar
IrJf was ver)* sandy and comparatively soft and little difficulty was
erienced in removiiig the brick from the invert,
♦ig. 175 shows two brirk taken from a 4.S X 72-in. egg-shaped
lion, built in 1S72 by contract of 8-m. brickwork laid in Rosendale
iii*iit mortar. Thesut two brick were taken from tbe side of the
ert on a section where the grade was 0.0200 and the estimated
city flowing two-thirds fi^lj^HBiBlL per secimd. The brick were
iingly hard and dense^^^^^m|gBg an absorption of 8 to 12 per

458

AMERICAN SEWERAGE PRACTICK

cent., and were worn very smooth, almost to a poli&h. The small e«
ill each case was the upstream end. The brick in the center of ih<* iq
vert were worn yery much more than those s!jowti, but owing
excessive wear and consequent thinners and also on account of tlial
of sewage, it was impracticable to remove any of thera. In this <ectld
some of the first, or inner course brick, were worn through and
second or outside course was beginning to ghow wear.

Fig, 176 shows another brick taken from the same sev
section as those shown in Fig. 174. Tiiis brick was laid in thel
in the position shown in the photograph. The right end ww
upstream end. There was a bad hole in the invert at this point and 1
mortar was so completely washed out that the brick was removed wilj
the fingers w^ithout the aid of a cliiseL Ali that is left of one of i
4 X 8-in, faces is the little dark spot shown in the foreground at
left-hand end. The brick was somew^hat below the average in ifualM
and rather porous.

Fig. 177 shows a brick taken from the ledge or step, above the inve
in a manhole constructed in 1868 by contract. The brickwork waa h
in Eosendale cement mortar. In this manhole there w^^re fiv«
pipe^ which discharged surface water from several catch-basins
inlets; they were so located that in time of storm the flow fr-
ww^ concentrated in a 4- or 5-ft, ch*op to the brick ledge of th-
The force of the falling water and detritus wore a bow*WhaptH!
pression in the ledge and side of the manhole. The left end of
brick shows its original thickness, being protected by the brick
the course above. This briek shows more clearly than can br
scribed, the effect of the w^earing action during a period of about i
years. The next two briek adjacent to the one shown wexe
even more and broke in pieces in removal ownng to their extreme thi|
ness. While this briek was not taken from a sewer invert, it show?* vc
clearly the effect of even a small drop in the flow line and the re^ultifl
wear on the brickwork, such as might he oMwrttH] frnni sirnn ir i-nndj
in the invert.

The mortar joints were eroded to a mucii -
brick, which doubtlei>s served to increase the w*
the eddy currents caused by tlve additional roughness. I'his was
entirely due to the use of Rosendale cement, fur the jolnta in the
above the springing Une were found to be in very good condiii^
Doubtless, some of the wear on the invert brick ha^ been due to (
ping action rather than abra*iion.

In all cases where lateral ttewerg on steep grades entered well up fr^
the invert, there were signs of considerable wear on the side of the
sewer where the stre^un from the lateral struck during times of sto

BXAUPLES OF SEWER SECTIONS

459

460

AMERICAN SEWERAGE PRACTICE

flow* In drop manholes and other places where a fall of 4 or 5 fi,
more occurred, the brickwork under the drop was badly worn.

On cui-ves constructed on grades producing velocities of 8 ft. per s
or morCi the brickwork on the inside of the curve was cut av
Beveral cases even through the second course of brick, A cr
Fig. 178a, of the interior surface of an egg-ahapetl section, 48 in, K^
constructed by contract in 1872 of two rings of brick with Rosco
cement mortar on a grade of 4.32 ft. per 100 ft., shows thia abraaioB"
of the invert on a curve. Fig. 178b is a cross-section of the i
sewer on a straight section. In each of the deep holes shown, the 1
course of brick had been worn away and part of the aecand.
dotted lines show the approximate original surface of the l>nckwn
These cross-sections were made by a specially coustnirtcd pantagiap
Soft brick were worn ranch more than hard brick, but where
soft brick waa surrounded by hard brick, even these were worn ma
than a similar section where the brick were all hard.

On flatter sections of 100 to 200 ft. in length on eitlit*r side of i
were steep sectionjs, there was some wear, due no doubt to the fact ih
the velocity in the tiat section although not greater than 5 or 6 (U ]
second theoretically, actually was much higher on iiccoimt of
influence of the steeper sections above and below.

It is interesting to compare the experience gained at WorcrntiTi '
information obtained at Louisville, Ky., from an inspection of oIJ
brick sewers. Where the velocity was high, there was but little wi*af <if
the brick, while at Worce^.er sewers having apparently the ssinr
velocity showed serious wear. The explanation is that at VVturisttf
the street detritus contains a large quantity of quartz sand coming f mm
streets which for many years were, and to some extent gtill Artt,
faced with gravel. There are also large deposits of sand and gjiti
in the city and the soil as a whole contains a large amount of qtj
In spite of the large nuiiiher of catch-basins in use, cousideralili? citno-
titles of sand and gravel find their way into th^ sewers, and Wf
detritus ifl carried along by the flow of sewage the invert brick \
worn by the harder material. At Ix)uisville, the soil i^ ccmi i
clay and disintegrated limestone and the stn_M?ts are sun
crushed limestone, which, for the most part, is softt'r limn thr <
brick. ICven in sewers constructed of relatively soft brick, say Ihui
testing between 24 and 30 per cent, absorption, there appejirs to lie I
little wear from the velocities which at Worce-ster !i
wear. Although doubtlesii the detritus wjwhed ^
Louisville does cause some w*ear, the attrition is much more c^lTtiH
upon the detritus itself than upon the sewer brick.

Fig. 179 shows two patterns of plaster casts token from the bf
of one of the Northern outfall sewers, middle level, 9 X Wt. aertinC'

EXAMPLES OF SEW^B SECTIONS

461

ng to the Barking works, London^ England. The upper pattern
Bboi%3 the eastern portion of the cast and the lower pattern shows the
Itern portion. The dotted lines show the approximate original
itlines of the brickwork and the approximate depth of wear can be
tfi^ed by comparison with the thickness of the brick. The mortar
^intii are indicated by heavy black lines » The most interesting feature
thme patterns is that they clearly show^ that the cement mortar in the
lints was harder than the brick themselves, and resisted the nvear
^nger than the brick did. This is exactly opposite to the experience in
ster, Mass. This is the only instance which has come to the
ation of the authors in which the mortar joints withstood the wear
tier than the brick. Although the old sewers in Worcester, Mass.,
i laid with Rosen dale cement mortar, many of them have since been
ti^ with brick laid in Portland cement mortar and in many cases
new inverts have shown considerable wear. It is possible^
Told sewers had been constructed in the first place >nth Portland
ameut mortar, that some such wear as that shown in Fig. 179 might
ilted although there are now no indications of such a result,
ll-size pattern from which Fig. 179 was made wa« furnished by
E, Worth, District Engineer of the London County Councih
be caat^ were made April 14, 1897. Mr. Worth states that the
^t?|mrtod relative condition of the brick and mortar was so unusual that
er casts of the invert were made in order to verify and preser\'e the

Uttiilg for Concrete Construction. — From the observations made
I le>t« conducted by the authors it api^ears that on all slopes in which
bp en u mated velocity of the sewage will be 8 ft. per second or greater,
't may well be paved with hard burned or preferably vitrified
i .„ brick with square edges, laid with the edges projecting as little
a« pONitKIe and with full Portland cement mortar joints. This invert
living should extend well up on the sides of the sewer, on straight
•©wew covering in general^ the arc of an angle of 90 dcg. at the center of
1^ circular sewer. The use of brick paving, as above suggested, is pre-
i^f«?r*ble to concrete on account of the greater ease of making repairs and
l^ortlaT on account of the probability that vitrified or even hard-
!irick will withstand the wear better than concrete of average
It is dc^sinible wlien sewers are to be built of concrete to use
'li-r i^utes, especially for inverts, and a first-class granolithic
*\k T^hiit' the surface b subject to greatest wear is better than the
innkty concrete finish.

SURFACE LOADS TRANSMITTED TO SEWERS

Loada,— Sewers constructed in shallow cut are often subjected
oa the surfaccj transmitted through the earth

462

AMERICAN SEWERAGE PRACTICE

filling. If the sewer line is crossed by steam railroad tracks there will
be heavy loads from locomotives or loaded freight cars; if crossed by an
electric railroad, there will be the loads from passenger or express cars,

Tablb 142.

Standard LocoHOTiVE Loadinos.

/:(})

I*- "J ■'-4-5" -4

(|) ([) 6 cp

-t:.

Ajitt5pCiCin9,fT.

5- »f J '

>pJ- "*^'"3'—-^5-^4

O 0^»4

Aile Lood

I I I I

Sf Sf ^ Sf

?*^ 0^ w#^ ffP

Urwfvnnt9a4

Airle load

I 1

_ I

^jOQOLb^lAft

i §

Ef S

^ -«

I , T .T ,1 , — . I ;7 : , '

in Ptpr

g. Ajclit Load

gill III

If

Sf

•I- From Cooper h Otntral Speufications f^Siml Ifailnad Bridga.
* From Trans. Am. 60C.C.F., ¥ol.SiA,p.eZ.

construction cars or snow plows, which in the case of the more recent
high-class interurban lines amount to approximately the same as the
loads on second-class steam railroads. In highways sewers are subject
to the loads of steam road rollers, traction engines, and heavy trucks.

Table 143.

Typicau Heavy freight Cars

w

^^

Axle 5pocing

Sl^eel Coal Cor 5

ys'e^ — 19' 9- ^s'e"-^

^ ^

Axle Spacing
in Tcrt-lnches

(•5'tf''»j*--

I7'9'

-*^S'6^*

Iron Ore Cars

^

^

%
^

5f ^

From Trarjs /^m ^oc C£ , Vc! 54 A. p. 85

For convenience in estimating live loads, four tables are given:
Table 142, typical standard locomotive axle loads and spacings;

EXAMPLES OF SEWER SECTIONS

403

>le 143| typicflJ axle loads of cars for heavy freight, such as coal or
30 ore; Tabic 144, typical axle loads of the heavy type of electric
for suburban serv^ice, and Table 145 the wheel loads ajid general
Bmensions of steam road rollers, traction engines and heavy auto-
ucks. Fig. 180 shows the details of standard railroad track

HJU.

i^^«ftte

n:

^(J^/^

Cros6 Section.

t

V

Subgrade

Side Elcvai-ion,
Fig. 180,-^»>tandard railroad tracic construction.

%

Ta&z^ 144. — Typical heavy electric cars.

Trorisit Co.
*907-J»Ton5

*^ litand HR,
l&07-53Ton*

i'50b'35Tons

*90e*50T&ns

Able Spacmg

Atle Load

TuT

KM

Ail« load

Axte Lood

Ajiie Load

AHle Load

OXD

~$^

S*Zi'^^'4'f"-^^

'5.45'^5.5'-i:^-

« ^

w'//rf'-k5-tf'-%

^8'9f^'6'-^ —

I ^

-JO'S- — j'.?'tf'V//i^

SJ iff

/g'//-- ■H*<yV''"WV

§

frcm Jot/r^. Ai%n, tn^. J^c. D^JS09 p. 241

464

AMERICAN SEWERAGE PRACTICE

Table 145. — Weights of Steam Road Rollkbb

Data furnished by The Buffalo Steam Roller Co.

1 Total 1 Load 1 Diameter of
^ . weight per wheel- whceb in inches

Face Width of
wheels in inches

Distance Widtl
e. to c. .of trac

"**''*'^ equipped in lb. ' ^

i in lb. 1 Front

Rear

Front

Rear

of axles in.
ft. in.

10 tons 26,000 | 8,670 i 44 69
12tons| 31,000 , 10,340 | 46 • 69
15 tonsi 39,000 13,000 48 ! 72

47i

51

521

18
20
22

9 10 :

10 8 .

11 1 1 94

Weight of Traction Engine
Data furnished by the Good Roads Mchy. Co.

16 h.p. 1 19,580 1 6,530^1 40 | 66 | 12 | 19

10 6 i 82

Weight of Typi

pal Aut4
~~42~

Draobile Trucks

5 tons 1 20,000^ | 6,900^ 36

! 6 ! 13

12 6 86

* Rear wheels.

* Allows for 25 per cent, overload.

The wheel loads from railroad rolling stock are well distributed ove
the road bed by the track, ties and ballast, so that for depths of eartl
fill of 5 ft. or more it is probably safe to estimate the axle loads as m
f ormly distributed over a somewhat larger area than that of the roat

Table 146. — Estimated iNTENsrriES op Surface Loads

Loaditiij

Locomotive, Coopers E30

Locomotive, Coopers E40

Locomotive, Northern Pac. R. R . . . .
Ix>comotive, At., Top. & S. F. R. R . .

8tecl coal car

Steel ore car

Electric car, Brooklyn R. T. Co . . . .

Electric car, Long Is. R. R

Electric car, N. Y. Interhoroiigh . . .
Electric car, Bo.ston and Worcester .
Electric car, Boston Elevated

Steam road roller, 10 tons .
Steam road roller, 12 tons .
Steam road roller, 15 terns .
Tra(^tion engine, 10 H.P...
Aiitoniohile truck, 5 tons .

Kstimated
equivalent in-
tensity of
load on
surface,
lb. per sq. ft.

630

840
1,100
1,500

740
1,260

380

650

370

470

410

lb. per. lin. ft.
of trench*

8,670

10,340

13,000

6,530

6,900

Assamed

dimeosions o(

loaded

suifaor.

ft.

19X10

19X10

19X10

17.5X10

9.5X10

9.5X10

8.1X10

9.5X10

9.5X10

10.5X10

10.1X10

• AM.HurninK woIkIiI of ono whcr-l por lini'Jir foot of trtMich. If trench is wide enool
to receive both rear wheels load uHsuined should be that upon the two rear wheel*.

KXAMPLEH OF SEWER SECTIONS

465

bed (firtjctly iinrler the loads. For locomotives, then^ the heaviest
^Qcentratioii would occur under the driving wheels, or in the case of
^rMf^oriieisBeDger cara, under one truck. In Table 146 are estimates
^ the ttitcii^ty of such loads on the ground surface.

Th« huh from the wheels of steam road rollers, traction engines^

^"acka, fitc, are applied directly to the surface of the fiU but over a

art»a. Although the intensity of the load at the surface is

becomes distributed fairly well over the entire width of the

^'^vh for depths of o ft. or more. In such cases the maximum load of

1 • iio|^ wheel may be estimated as distributed over 1 Un. ft. of

wTwre Ihe crown of the sewer is not more than 5 ft. below the surface,
j|*a iDereaded load may bo assumed on account of the impact and \ibra-
i caosed by swiftly moving trains or cars. In the case of express
^'^a* mo\*iog at a high speed this impact may possibly produce a load
**'' Wow 50 per cent, greater than the load when not in motion.
Dead Loads. — In manufacturing districts^ sewers are often' subjected
Iwtkvy surface loads from piles of lumber, brick, pig iron, coal, etc,
^Tierever such is likely to be the case ample allowance should be made,
ommon to find surface loails as high as the following:
. per square foot; brick, 900 lb.; coal, 1200 lb.; and pig
ll,2300fb.

There are eaftL-«, duubtlei«*, where heavn^ masoiu^^ foundations have
1 built over gcwcra without regard for their stability. Wherever it
to do such work, either the sewer arch should be strength-
Rarry the excess load, or preferably the foundation in question
ould be built so as to relieve the sewer arch of all of the load of the
Dding or st nurture.
Prciportloa of Loads Transmitted to Sewers.— The best information
jfc'V'ailahlt: (in I9\i) as to the weight of superimposed loatls or surface
transmitted t<; sewers will be found in BuLletin 31, Engineering
experiment Station, Iowa State College, **The Theory of Loads on
rtpts* in Ditches," by A, Marstou and A. 0. Anderson. An abstract
jjart of tliis work will be found in Chapter X, on Sewer Pipe, In
y\ IK I are plotted curves of the values of C in the formula Lp = CLt
rtcrc £/„ ih the total load per unit of length on the sewer, C is a coefficient
I whicli ttllu wan(H5 is made for the ratio of the width and depth of trench,
M of the backfill againi^t the sides of the trench, and for the
1 be backfiUing material; L is the surface load per linear
- (.4 trench; H is the width of the trench at the top of the pipe, and H
> the height of fdl in the trench above the top of the sewer.
By **hmg lomls" arc mcjint those which extend a long distance along
encb as compared with its width and height. In this class come
a« thoao resulting from piles of brick, lumber, pig iron, coal.

466

AMERICAN SEWERAGE PRACTICE

etc., and possibly in freight yards from long lines of cars on storage
tracks.

By ''short loads*' are meant such as those from road rollers, trucks
or wagons, and in general, all of the other ''live" loads pre\'ious]y
mention€»d.

The cur\'es in Fig. 181 will be found of value in estimating the
proportion of the weight of surface loads that might be transmitted
through the backfilling to the sewer. All such loads, after having
been reduced in the proportion shown by the curves or as aided by
judgment, should then be changed to the basis of an equivalent earth
load, for convenience in designing. By this means, the backfilling and
surface loading will be reduced to the same relative unit weights and
can be considered together as a certain total depth of backfill.

0

wo

0.20

a-jo

Coefficients

a4o aso

c.

a60

O.TO

CM

a90

\»

\ \ \ \

1 :£=^

^

BB^

^

1

. ,\

^

-^-^^

^^

^--

r""^

^

-tMLi-""""'^

_i5

\^

^

J

.•^

A

r^

. ^M

i^

^

t^

f^5

^

^■^

.rf*.^

f

I*

v^-

f

\A

^

"7

r

-^

-^

U

' /

t
t

/

f^

I

f

d

f

«»

III

/

\&

I!

n

Fig. li>l. — Coefficients of surface loads transmitted through eaii.u fiJi ^^

sewers.

For example, the depth of earth over the crown of a certain sewer is 20 ft.
and the width of trench at the top of the sewer is 10 ft. The backfiliing
material is sand wei>;hing 120 lb. per cubic foot. One section of this sewer
is to be built under a coal yard, and accordingly there should be added a
surface load due to piles of coiil of 1200 lb. per square foot. The total
*'long load" per linear foot of trench, L, would be 1200 X 10 = 12,000 lb.
The ratio of height of fill to width of trench, H/B = 2. On Fig. 181,
follow along the horizontal line II IH = 2 until it intersects the curve for
Siind and damp top soil for long loads, which point is on the verticalUn®
(interpolated; for coefficient T = 0..')2. Substituting in the fomwila I^ "
CL the values of (' = 0.02 and L = 12.000, we have Lp = 0.52 X 12,000 -
6240 lb. per linear foot of sewer.

Since the width of trench, /?, is 10 ft. and the assumed unit
trench filling is 120 lb., the equivalent earth load of Lp = 6240 lb
foot is 6240 4- (10 X 120) » 5.2 ft. of sand backfilling.

wci
.per

ight

of

linear

EXAMPLES OF SEWER SECTIONS

467

WEIGHT OF BACKFILLING

ng work, it ia sufficient to assume that the backfill
10 lb. per cubic foot and that the horizontal pressure at any
> this fill will be one-third of the vertical pressure. Where
exact assumptiom must be made, the materiul vfliich will
Id be actually weighed, in a moist as weil as a dry condition,
Qation given in Table 108, page 334, should be employed.
>f the whole of the backfilHng ia not transmitted to the sewer
I, but only a part, whieli may be estimated from Table 109,
d its accompanying explanatory text. It give^ somewhat
res than Rankine's formula, explained in Volume II, and
On florae engineers are inchned to defer its use until ex-
fihown that it is safe to employ tliese lower prejisures.
Theory. — When the Rankine theory is used in designing
, the surface of the earth ib usually assumed to be horisiontal.
rth pressure acting on a section of a sewer arch may be
I composed of a vertical component eriual to the weight of
f earth above the section, and a horizontal component which
I cannot be greater than (1 + sin 0) /(I — sin ^) iimm the
Hire at the same point, nor less than (1 — sin 4>)/{l 4- sin ^}
rticul pressure, ^ being the angle of repose. The former
(presents the passive resistance of the earth, while the latter
^^^ttvc pressure which, at least, is probably realized.
^Hpiken as 30 deg., which is a convenient figure to use and
JBents average conditions, the above statement means
izontal prei*sure cannot be greater than throe times the
rure nor less than one-third of it. While it is reeogniised
ogical course would be to use exact viilues for the angle of
rtter; the angle of internal friction, this is hardly justified
conditions because of the great uncertainty regarding the
ih prcjssures and the variation in the character and condition
terials.

es in which the sheeting will be left in place up to witliin
the t»urface, care should be taken in Ui^ing formulas similar
on account of the fact that the sheeting introducei^ different
ui prevents cohesion between the backfilling material and
the trench, which might otherwise exist. It is probable
Rheetinl trenches newly backfilled, almost the entire weight
ill may come directly on the aewer structure. On this
a tiuestion whether a designer is justified in reducing the
of f^arth transmitted to the sewer by any such n^ethods aa
icribed. It iii often impossible to tell in advance whether

Eft in pkoc or not. In the practice of the autbora it
L.

hus been customary to assume tlriat the entire weight of the earth ^^S.!!
will be transiiiitied to the sewer, even though tt is recogaized tliat i b
many oases no such severe loading is encountered. On the other ha:Mrm.<I
the actual weight of .superimposed loails transmitted to the ser^^^^
niay ver>^ well be reduced in the manner »ugge8t«d*

Mohr's Method of Determining Pressures, — ^A graphical method ^laf
determining earth pressures, devised by Prof. Mohr in 1K71 and fnunrE^^Md
on Ranking 's thoon»^ was de-seribed by Prof, G, F. Swain in the '* Jaunica^ "
of the Frankliji Institute, vol. cxiv, p. 241. It i^ ad follows:

I

Flo. IS2.

Let a horizontal hne .4^ Fig. 182 represent the »arfaoe of the ear*-*'*
Draw /// perfiendieular to AH, and of mtUQ convouient length^ as oi*^**
©quivelent to 10 ft, on a acale of 1 in, to 1 ft. Lay off UK of lenj^^

HK ^ Hi tan»{45^ - 1^)

^ =^ angle of repose. This will be recognized as oqui val«)nt to Rioikii*^ •
formula for the intensity of earth pr©sfeure» with «>, the unit wtigl^^ **

earth, onutted.

P - uh tan»(45^ - J<^)

where P = the in*^
h ^ the dej)ih of *

n*r*U

vmmmt^

maA

EXAMPLES OF SEWER SECTIONS

469

ing located pot at A', with KI as a diameter, describe a ctrcte,
;h / draw a lino IW parallel to the face of thewaJl or sectioa of
>on which the preHsure of the earth acta. Draw ViK through the
Vi and K on the circumference of the circle, and prolong it to meet
liMnjnp AH* At thi^) point of intersection A, draw .4/, which
HPiPltltion of the active pressure on plane L The distance
Beasures the magnitude of thi^ pretiaure for the depth repre-
by HL {HVi/HI)tv is the inten^sity of active presuurc per unit
of earth on plane 1. The magnitude of HVi can be obtained by
; the line HVt. In a similar manner the direction and amount
I active pressure on any other plane, as plane 2, can be found.
1 amount of the maximum passive earth prasaure is measured by
r a depth of HVi (//////Fi= intensity") for plane 1, or by ///
epth of H Vf for plane 2. The direction of the maximum passive
^e is found by drawing through Vi, V's, etc., a diameter of the
and then connecting the point of intersection B with Lr Line BI
direction of the maximum passive pressure for plane 2, It is
idicular to the face upon which pressure is exerted.
te is an exact mathematical proof of the foregoing, but the follow-
neral proof will probably be sufficient.

tk the figure we let the line HI represent a vertical plane, we have
i HK of such a distance that for the depth ///, HK represents the
ty of the active earth pressure.

an be proved that as the plane of the wall slants away from the
id, a circle of diameter KI will contain all the points V for every
m of the plane, the intensity being HV/HI until a horizontal
I is reached which has a pressure of HV/HI => HI /HI =* 1, or
;a1 dead weight of the earth above the plane. The angle IH V iB
(gle Sf or the angle which the stress makes with the normal to the

m Rankine's thcor>' we know that the angle S can never exceed the

of friction ^, or the angle of repose of the earth. HenoCi if we

from // two lines making angles of <^ on either side of HI, we know

rcle must lie within those lines, and when the earth is just outhe

of slipping S = 0 and the circle is tangent to the two lines HD and

There are two circles which satisfy the conditions representing

W<i limiting st-ates of etpiilit>rtum wheu the earth is just ready to

" .::er circle, only p/irt of which is shown in Fig- 182,

f' case where the maximum principal pressure HI is in-

p until the liiniiiug condition is reached. This is the passive

fr — ^' " T'' lualler circle represents the ea^e where the mini-

ilK is deMTcased until the limiting condition is

liiMt IN the active earth prevHSure. In the case ot 4» - ^^***

Kc- iu'nri* t^ drawn* the passive earth pressure is 9 times tlie

470 AMERICAN SEWERAGE PRACTICE

active. It is not necessary, however, to use the large circle, since for
the active pressure

1 - sin ^

Pa = Wh y~-. 7

1 + sm ^

and for the passive presssure

1 + sin ^
1 — sin ^

P, = wh

the term (1 — sin ^)/(l + sin 4>) being merely inverted. The inversion

has been accomplished as follows:
The active pressure per unit depth = w(HV/HI)
The passive pressure per unit depth = w(HI/HV)
The angle IHV ^ the angle S, the angle between the nonnaltotb^

plane and the stress. Therefore, having this angle, we can erect a noriiw

to the plane and lay off the angle 5, thereby obtaining the direction <*

the stress. For example:

angle lAVi = angle IHVi

ANALYSIS OF MASONRY Al

"^Tbei

Tliere are a liuraber of methods rti uae today for analyzing the stressea ia
ches. While a considerable proportion of existing Iftrge masonry sewers
vti been designed without any analysis of the stresses, the In (Teasing use of
forced concrete sewers is responsible for a more general effort on the
rt of designers to analyse the stresses in these structures.

the following pages, three methods of analysis are described and the
ams and computations for each applied to a 15-ft. 6-in* X 15-ft. 2-in.
■shoe sewer aeolion are given,
first method, called the **voussoir arch method," based on the so-
lypothosis of least erown thrust/* is applicable only to that portion
•er section above the springing line of the arch. Either the sewer
ust have very heavy side walls or the thrust of the arch must be carried
the sided of a rock trenoh in order to make this method strictly
[cable.
second method^ baaed on the elastic theory of the arch and following
e method described by Turneaiu-e and Maurer in their ** Principles of
[forced Concrete Conatniction" is applicable to all sewer sections and
be used to cover all conditions. It has some mechanical disadvantages
hen applied to the analysis of the entire sewer structures invert included.
The third method, also based onthe elastic theory but using the so-called
lethod for indeterminate stj'uctures, is of special advantage in the anal^'sis
the entire sewer section as it permits a more suitable division of the axis
the side wall and invert. It does, however, require some additional
over the second method when appHed to an arch with fixed ends. For
■ge sewers constructed in compressible soil and built of monolithic rein-
forced concrete, the third method is the most desirable.

Attetition is particularly calh^l to the fact that in the following analyses
;he terms ** elastic theory" and ** method for indetermuiate structures" are
tsed merely to distinguish between the two niethodi*. both of which are based
n the elastic theory* and are appl legible to indeterminate structures. The
nicUcal diflference between the two is in the method of subdividing the
h axis.

Since the three examples given are based so far as practicable on the same
assumptions, a direct comparison may be made of the results obtained.
Another method has been used by some engineers, that of Prof. Chas. E.
irecne fur an arch rib with fixed ends. Reference '* Trusses and Arches"
•art III, by Greene. According to W. W, Horner, Principal .Vsaistant Eng.,
It. Louis Sewer Department, this method waji used for the earlier arches
!e«igned under his direction. Later, it wns worked up in the form of general
formulas for each lO-dcg. point on the areh, Sinular formulas have beea

471

fthor (

472 AMERICAX SEWERAGE PRACTICE

published by A. £. Lindau, Traru, Am, Soe .C E. vol. Ixi, 190S, p. 3S7.
Mr. Homer stated that ''this method is satisfactory where the arch re^
on rock or on a heavy invert, but the introduction of a side wall of over
a foot in height causes the whole structure to depart somewhat from
fixture at the spring line/' He further states that Greene's method was
used in 1914 to give a trial section for all larger arches or work of especial
importance and that the work was checked by the elastic theory' method of
Tumeaure and Maurer.

ANALYSIS OF ARCH BT VOUSSOIR METHOD

Masonry arches may be divided into two general classes, voussoir and
monolithic arches, the former constructed of separate stones or bricks, while
the latter are monolithic. In designing concrete arches, they may be con-
sidered as composed of a number of sections, in which case they come under
the voussoir classification. Sewer arches may be further classified as hingeless,
that is, with fixed ends.

There are a number of theories on which the design of voussoir arches has
been based, but the one most generally employed is the rational theor?',
based on the hypothesis of least crown thrust. The following application
of this theor>' to the design of sewer arches is based on a discussion in Baker's
"Masonry," tenth edition, page 620.

According to the hypothesis of least crown thrust, the true line of resistance
of the arch is that for which the thrust at the crown is the least possible in
amount consistent with the arch being in a state of equilibrium. This
theory asssunies that the external forces acting on the arch create a thrust at
the crown sufficient in amount to establish equilibrium in the arch, and
that when this state of equilibrium hasj)een established there is no need for
further increase in the amount of this thrust and that therefore the thrust
is the least possible consistent with equilibrium. These assumptions do not
of themselves locate the line of resistance, but if the external forces are knovu
in amount and direction, and the direction of the thrust is assumed, sufficient
data will he provided to locate the line of resistance corresponding to the
least possible crown thrust. The rational method assumes that the earth
pressure acting on the arch is composed of vertical and horijontsl
components.

The direct determination of the line of resistance for an arch unsymniot-
rically loaded is practically impossible under this theory. As a general
rule, however, sewer arches may be considered as being sj'mmetrically
loaded, and the following exarnj)le is based on this assumption.

Ijot us assume that it is desired to locate the line of resistance of the 15-ft.
()-in. span concrete arch shown in Fig. 183, the relative thickness of the
nrvh having been assumed, either with the aid of some of the empirical for-
mulas j)revi()usly given in earlier chapters, or in the light of experience with
arches already con.structed. As it has been assumed that the arch is sjinmet-
riwilly loaded, but half of the arch section need be drawn, as shown in the
figure. Assume that the arch supports a depth of earth of 24 ft. above the
crown, and that the unit weight of earth is 10() lb. per cubic foot and the
unit weight of the concrete masonry 150 lb. per cubic foot.

THE ANALY&IS OF MASONRY ARCHES

473

474

AMERICAN SEWERAGE PRACTICE

In order to simplify the computation the design will be based on a aeetion
of the arch ring 12 in. thick, perpendicular to the plane of the paper. Als
divide the center line of the half-arch section into eight equal parta, separated
by radial lines as shown, to serve as the theoretical voussoirs for analytiol
purposes.

Vertical Forces. — The vertical forces acting on the aroh section are the
weight of the concrete section and the weight of the column of earth abon
the section. The weight of the concrete section acts through the center d
gravity of the section, which for practical purposes may be assumed at the
center line of the arch for that section. The weight of the earth prism abort
the arch may be assumed to act through the center of the horisontal proje»
tion of the extrados of the section. The center of gravity of the combined
vertical load, that is, the weight of the concrete plus the weight of the
earth, can be determined by moments, either analytically or graphieallr.
The value of the weight of concrete, the vertical earth pressure and the
sum of these two are given for each section in Table 147.

Table

147.— CoMP

UTATIONS OP

Forces

1

2

3

4

5

6

Weight

Vertical

Total

Horizontal

Resultant

Section

of

earth

vertical

earth

force

number

concrete,

presflure,

force,

prcflflure.

on aectioB.

lb.

lb.

lb.

lb.

lb.

1

230

4120

4350

140

4350

2

230

4000

4230

390

4250

3

240

3820

4060

650

4110

4

250

3540

3790

920

3910

5

270

3120

3390

1170

3590

6

290

2510

2800

1430

3140

7

310

1780

2090

1650

2660

8

330

890

1220

1850

2220

Horizontal Forces. — Follc^wing the suggestion in regard to the intensiiy
of the horizontal earth pressure given in a previous paragraph, if we aasume
the angle of repose equal to 30 deg., the intensity of the horizontal earth
pressure will be one-third of the intensity of the vertical pressure at that
point. The values of the horizontal earth pressures computed in this
maimer for each section, are given in Table 147.

Crown Thrust. — The section of the arch shown in Pig. 184 is held in
equilibrium by the vertical forceps due to the sum of the weights of ooncrete
and earth prism, by the reaction R at the springing line or abutment and by
the tlirust T at the crown. The direction of the reaction at the abutment is
immiiteriid in this discussion. lA^t //„ = the thrust at the crown; Xi = the
horizontal distance from the point of application of the reaction on th*
abutment to the line of action of ?/', representing the total vertical force on
the first section of the arch from the crown; Xt = the same for ir^; etc.; y •
the vorticral distance* from the point of application of the abutment reaction
to the line of action of //.,, the thrust on the crown; Ki » the perpendicular
distance' from the point of applicatino of the abutment reaction to theliM

THE ANALYSIS OF MASONRY ARCHES

475

of hit the horizon tat force acting on the first section of the aroh;
the sjtme for htt etc. Then by taking moiuonta nbout tiie point of
liciition of the abtitmcnt reaction we have the following equationa:
JI„y = «j|X| + Wtz% -h etc. + hiKi 4- h^Kt -f etc
i this we obtain,

^^-' ~lf "

the above equations it appears that, other thingi remaining the
Df , the liirger y the smaller //«, and therefore, iji order to f»litnin a minim um
' of the thrust H^, the point of application of the thrust at the crown
I be as near the extrados aa is possible without stressing the masonry
\h\%h. It b usually iissumed that the thrust acts at a point one-third of
^drplh of the arch from the extrados at the crown. This assum ption means
t Iho unit compressive stress at the crown is equal to twice the thrust Ho
Fided by the thiekness of the arch at the crown, the length of arch section
as unity^ which has ah'eady been assumed.

Fia 1S4.

I It in alao mumlly asflumcd that the tliruat is horhBontal in direction. If
« trically loaded this assumption is a reasonable one, but for
tiic rtrch is u/isym metrically loaded the thrust at the crown
N<ut fve )iori«ontai and on that accoimt a direct determination of tlie lino
'w'AtgUaol' by this method is impossible,

I'Jiutof Rui»ture.— The value cliusen for the crown thrust //* must be such
'^ 'ho i»t*nu-ar*!h will be in equilibrium. If //« is tmj small some one of the
*<»» riiHy iipen at the oxtrrtdo8, and on the other har>d, if H^ is too largr, somn
"* " 1 i«y optTi at the intnidoM. 1 1 in evident that neither of these

rrfiuli in a eomlition of equiiibrium under the a&sumption
ocattrr iif pressure or line of resistance must remain within the middle
toint. If Hie line of resistance is so located, there will be no
I >mt^and consequently there will be no oi>emn« of any
' vxtrados or iiitrados. The required value ol //.

WSl

^£

=11111111

^ 1^ « to i-T h." :c >ft -f

«2

^ -N ^ ^^ © ^_ ^_ -,- CB^,

«d

1

,2
i

*<

<

K

•<

'-' « c* ^

i

2 2?3S

i

2 SS52S2

^ — e^ !<; lii CD

m
*<

S § i 2 S g 5

"-^ O ^ rt ^' « r*

i

^ 3 -M «s M ut* to X

t<

1

1

i?

1

fr

5^
f 1

i?

^ ode

N

S 6 6" —
1

H

s 2SSSS

"^ C ** -* M 9f

H

5 8 2 S St S 2

*^ d -• 64 M ^ ^

(7

*

5 3^§?3S5$S

^

:i ** CI cr:

11

If

**

m

1

f i

will therefore be that vahie whil
will keep the line of rcaistaucowrtJ
the middle third of every ioint

If &j the origin of moment!
point of apphcation of the reiididj
at any joint, ais in Fig. IM, be tjikei
Hucceasively at the inner or lowti
end of the middle third of each join
the corresponding vahie fif fh will t
the crown thrust for which ihjit (
trculAf joint is on the point of opcnii^
at tfi^ extrados; and If under
condition the greatest %*alue nf J
that will prevent any joint ffoil
opening on the intfados be hum
then that value is tlie crown iK
requiretl by the hypothesis, fof
snmllcr value will permit une ornioi
joints to open at the ext nidus ftW
a greater value will amm onu
more joints to open at the irrtraii'^

The joint for which the t-e«dcnt(
to open at the intradoa i«
greatest is called the joint of niptu
Practically speaking, the joiiit
ruptiire is the tnie springing lin« '
the arch and the rest nf thr *f^
below the joint of rupture ta tn i
ity a part of the abutment of ^^
wall. The next step in the arch '
aiysis is therefore to find llie ioio*|
rupture*

Crown Tlinist for Joint ^upt
Tlin total vertical forces rw c«jri>p*J^
are given in Table M7. The
ment arm of each of thcj*e foru
weights, with reference to I ho I
origins of nmmrnt, h mrasa
eniered in Tnble 148. In Td
are columns beaded '* Arm* i
tical Forces'* and below Ui»»«<t ^1
rieg of columns headcti *^\jmi* 1
Hori;&ontal Forces.** In ctiiuia*!

THE ANALYSIS OF MASONRY ARCHES

477

[point of joint 2; 3.66 about the lower middle third point of joint 3;
labout tbts lower middle third paint of joint 4. In the same manner
|m oolumri 3 is the arm of the weight, wi about the origin of mo-
! lower middle third point of joint 2.

ri^antnl forcers as ooniputed are j^iven in Table 147, In a similar

rti' I above, the arms of the horizontal fortiefij /ii^ As, etc, are

jM anu I in Table 148. The moment arms of these horizontal

ld€note<l ?w* A'r, /t j, etc., are shown in the bxldos. For exitruplt% under

10, 15 0.60 the perpendicular distance* from the horijtontal force hi

\ lower middle third point of joint 1; 1.15 is the perpendicular distance

J the horizontal force hi to the lower middle third point of joint 2, and

! value of y, the moment arm of the crown thrust, is found by scaling

awing, Fi«. 183, and h recorded in Tal>le 148» For example, 0.47

umn IH is the perpendicular distantjc from the crown thrust, assumed

lftp()lied at the upfjer middle third of the c^o^^^l joint, to the lower middle

Ipoint of joint 1^ and so on for the other values to the origin of moments

I tjcveral joiuta.

nesct fitep is to find the sum of the moments of all of the vertieal
I to the left of each of the orig;ina of momenta of the variouu joints, that
r joint I, the moment of the vertical foreeat the left of that joint equals
dint 2, the mornc^nt of the vertiral foroes equals wui -f u^jj-jand so
1 of the other joints* The momenta of the vertical forces about
of the jointj3 thus found are recorded in column 19.
ismnlar manner, find tfie moment of the horizontal forces about each
md n*ciord the sum for each joint in eolumn 20.

> tot-al crown thrust forearii joint is then found by adding the moment
I tlie vertical forces and the moment due to the horbontal foroea and
thy the larger arm, y, of the crown thrust.

„ Zwz + UK

Ho =

I value of the crown thrust thus obtnined is recorded in the column 21
bio 1-I8< An inspection of this column shows that the crown thrust for
[4 it the greatest and therefore joint 4 is the joint of rupture.

! Dlagranu^llie maximum crown thrust for the joint of rupture haa
Ix'cn found as 17,100 lb. To conKtruct the force diagram, a hon-
line iji drawn to scale, see Fig. 183, to represent the amount of the
nmn i^T'nvn thrust as found for joint 4. This may be drawn at any
^ 1 in. = ',i,(HX} lb. From the left end of th«» horiKont^I
BT! firsit vertical foroe, vertically downward and from its ex-

f lay olT A, hortjsontally 1^ the right. Then the line from the right ex-
' Ai to upprT end of w^i r<*preseiit8 the direction and amount of the
BictRmat f^^rfe, f'j aottng upon tlie first division of the arch ring.
' * ' f extTemity of Ai, or the lower extremily of

r»* r»f th« first arch stone upon the one next
• \\^>war'l from the right extremity
f hen a line P^ from the upper end

478

AMERICAN SEWERAGE PRACTICE

of Wi to thp right end of ht repreBents the remiltant of the externjil lorm
acting on the second rJiviaion of the arch, and a line /?« from the lower exifeo-
ity of Pt represents the resultant pressure of the second arch stone on the tbii^
The force diagram is completed by drawing lines to represent the other valflj
of w^ h^ P and the corresponding reactions. The broken line Pt< Pit Ph^
is sometimes called the "load line," as it reprejjents the external foroea actini
on the arch in direction and, by scale, in amount in the order of their applka-
tion to the arch, starting from the crown and going to\*^ard the sprtnginir line.
The rndiiil lines from the several points on this load line to th*" ' f

tlie horizontal line are called the '*rays" and represent in directioJi
the successive reactions or thrusts of one arch stone against the next sectioit
below.

Line of Resistance, — On the arch section through the several point* of
application of the horizontal and vertical forces, draw tlie resultant foi
acting on each arch section. These may be taken from the force diagrnm*

To construtrt the line of resistance, draw through the upper limit of t
middle third of the crown joint a horizontal line to an intersection with tlie
oblique force Pi acting on section 1 ; and from this point draw a line parall^^
to Ri and prolong it to an intersection with the oblique force Pi acting on
section 2 of the arch. In a similar manner continue to the springing lina

The int4?rscction of the line parallel to Ri from the force diagram with I
first joint gives the center of pressure on that joint; and the intersedion i
Ht with the seoond joint ^ivQs the center of pressure for that joint and au^
for the other joints.

On account of the method used, the line of resistance must ptus thr
the lower middle third point of the joint of rupture. This offers a relialj
method of checking the accuracy of the work of drawing the Ua**]
resistanoe.

The equilibrium polygon gives the resultant pressure acting on each Joil
The thrust, normal to the joint, and the shear can be for»ned by rwit^hiil
the resultant pressure Into its two components tangent and perpeodlculAf 1
the arch axis at the point in question. The values may be obtained by I
ing those lines shown broken in the force diagram Fig. 183.

Having given the location and amount of the thrust on each joint, I
stresses fur that joint can be computed^ as will be explained in » ^
paragraph.

ANALYSIS OF ARCH BY ELASTIC THEORY

The method of analysis of an arch section, based on the elatftif I
assumes that the arch is held in equilibrium by its resistancf* to ceinbij
oornpn'ssion and bending, that is, the an^h is ctinsidered as a curvod bisiUii.
This method is appHcable to all liingelesa arches of vari
inertia and to any system of loading, although the work is \^.
when the loadn are synitnelrteah As a rule, sewer iirohes can be owtiAitJcc^''^
as t>eing gym metrically loaded.

For a mure eomplete di»eu«aion of the theori**s and nw

Lii is here giv

TffB A p^ Air SIS OF ^fASONnr arches

470

M. A. Howoij a "Troatiae on Mjisoiiry Condtruction;'* by l^ot
). Baker, "Concrete, Plain and Reinforcpd,** by Tnylorand Thompson,
^Prineiplca of Keinforced Concrete Conatmction/' by Turneaure and
The method here given is that explained by Turneaure and

^l>*siB of an arch consists of the determination of the forces acting
tion, uijtualJy expre.^M?d a^ the thrust, the shear and the bending
lich sections. The thrust is taken to be the component of the
llel to the arch axis at the given point and tJie ahear is the
acnt at right anglea to such axis. The thrust causes simple compressive
«, the shear causes stresseiS similar to those produced by the vertical
• in a simple beam.

I thw atiatysis, the length of the arch will be considered aa one luiit pcr-
iioular to the plane uf the figure.

Lot //• = thrust at the crown,

V*p « sheiir at the crown,

M» — bending moment at the crown, assumed as positive whin
causing compression in the upper fil:K?r8,
and Af — thrust, shear, and monient at any other section,

R = rcHuiUirit pressure at any section = resultant of A^ and V\
fU ■» length of a division of the arch ring measured along the arch

axis,
n ^^^ nund)er of divisions in one-half of the arch,
f = moment of inertia of any section = / (concrete) + nl (steel)
where w = 15 = E./Et,
\e^ h^ P =* the vertical^ horizontal and resultant externa! loads on the
arch, rcHpectively,
X, V ^ co-urdinates of any point on the arch axis referred to the
crown as origin. All positive in sign,
TO « bending moment at any point in the half arch flection, Fig.
186, due to extjCTnal loads. iUt negative in sign*

r ^mmetrical loads, the following equations can be derived:
nILmy — ZmXy

H.

Xm±IhZy

I . - O

lint ions an? for t!ie half arch scctioiL
ug moment at any section

M ^ m 4- M, -f UuU

I foUuwing analyHls based on the dastio theory and using Turneaure

ttr«*ri method, two casi^s are considered,
l* (Fig. 185). ^In rhiH vii>it} the invert is considered as being gepa-
' ^'" ' ^U find arrh, and the elastic 8t.rtictiu*e to bo finalyxe<l
* y wall and arch section* Tliis assumes that the base

480

AMERICAN SEWERAGE PRACTICE

of the side wall is fixed, that is, the arch is htngeless. Such a oonditioii \
exist where the sewer is constructed in rock cut with the baae of t
walb or the invert resting on ledge rock. If the rock extended to i
above the springing line or horizontal diiimeter of the £$em i- circular i
analysis might properly be confined to that portion of the structure i
springing line of the semi-circular arch, as the ends could then be ^
a0 fixed at that point.

Caae II (Fig. 186). — ^This case differs from the preceding in that I
entire structure, invert included, is considered as an elastic monolith i
oonsequejitly subject to direct stress) and bending at any point. Suobi
condition will be reached if the sewer is constructed in oompretsslblosoili

acta as ring. Reinforoed-cjoflrHe
sewers ooostructed in sand, ^
or day without special foun<i
should be treated under this caic
Analysis of Case L—In the fd-
lowiog discussion, the term sfch i>
used to denote that portion d ib»
section from tha crown to tha ba*
of the side wall or the bejpiiniit^ "^
the invert. The hii!f-nrt-h ^<^J '
is drawn to some * ' '^*'

which should be s I i^^^

to enable all distances to be .nrnlt '
without appreciable error, 1^'^-
half-arch section under ooMidtfi'
tion is shown in Fig. 186*

thfi^ion of Atth Rinn ta CtVft
CansUtni d*//.~The first step m tb«
analysis is to divide the half-ftf^
section into a number of diviflofl*
of such length that the ratio of da/l wfll be constant for each section* Th*
following method of determining the sucoeasive divisions of the iircli ^
taken from Biiker's "Masonry,** 10th edition, p, 676, While then* niv *
number of other methods which may be used, this is one of the uirnr ' '
Since the moments of inertia of the several sections of the arch vary fts^ ^^^^ ■
cube of the depth, it will be necessary to make the divisions Maw i
springing line oonsidernbly larger than those near the crown an^I
count, in order to avoid exwssive error, the divisions at the croti '
made comparatively small. The fir«t step is to divide Uie arch ai
any number of equal jmrts^ wliich^ in the case at hand is 15. ^Tpij?
radial depth of the ring ut each point of division; dptennine i
arch axis either by dividers or computatioOi and lay aflf this k .^
a hori»ontal lihe, as in Fig, 186;. divide this line into the samo nuiul^^
equal parts .is the half-arch section and at each point of <^ " *
vertical equal by hc«Ic t^ the moment of inertia at the eorr
on th<^ iifjit of tti

where : , to be ex^

THE ANALYSIS OF MASONRY ARCHES

481

tlwj raoment of inertia of the concret<i aection plus n times the moment

>rtia of the st,eel section, for the arches usually designed in sewerage
ct it will J»e KUlhciciitly accurate tro considex the moment of inertia of

mncn't^i st^rtitm ulone^ neglecting the steel; and since the moment of
in proportional to the cube of the depth, the latter quantity may be

instead of the nioment of inertia for the length of the vertical line, aa
iod above. Connect the tops of theae vertituils by a smooth cur\»e. It

ih^a be aMSumod that any ordinate to this curve is proportional to the
nt of inertia at tbo (Corresponding point on the arch ring,

\ divide the aroh axis into portions of such length that ds/I shall be con-
draw a Une alt^ at any slope and then a line^ 6c, at the siime slope, and
m the construction by drawing other isoaeelea triangles as shown,

^n using the same slope. This divider the rectified arch ring into a

Ikit of parts of such length that eaeh purt, divided by the moment of
I at il*» center, is o«ii»stant, that is, ds/I = 2 tan o, in which a is the
between the aitles of the isosceles triangle and the verticaL
Table 140 are given the values used in the above computations for the

toD of the arch ring.

Table 149, — Division of Ancn Rinq

AnalytU of l*Vft. O-iii. X 15-ft. 2-in, lior9«->flhoe Sewer by Eltutic Tbenfy

1

2

3

4

1

2

3

i

rtkm

RadiAl
a»r>th of

t"

VftluM
of<2#

number

tudimi

depth of

(•

Vlk1u(^«

pm

0,917

0.76

11

1.48

3,24

1.12

1

0.92

0,78

0.03

12

1 67

4,66

1,29

2

0.93

0.80

0.63

13

1,92

7,09 1

L54

3

0,96

0,88

0 03

14

2-24

11,22

1 96

0.99

0.97

0.04

15

2 95

25.65

5,34

1.04

M3

0.66

1^6

1.90

6 86

4.64

! 0

t 09

1,30

0 09

17

1.71

5,00

1 92

f T

,1.15

1,52

0,75

18

1.51

3 44

1 21

A

1.21

1 77

0.80

19

1,30

2 20

0 98

L2S

2.10

0.88

j 20

L12

1.41

Ifl

I 3 ■>

2 4«

0 98 1

' Invert c.

LOO

1 (X)

ii not important thai a point of division shall full exactly at the end of

1 1 lini% but in rase it is desired to divide the nroh ring into a

f fHiTnhor of part«, this can be done by sui-^uessive approxima-

ingle or protractor will be found of considerable as-

»* I ihc arch ring in this manner,

lUian4, — The sewer section shown is assumed to be subject to an earth

ft, above the top of tiie sewer. The weight of the earth filling is

to be 100 lb. per cubic foot, and the angle of repose is taken as 30

!■ further assumed that the server is to be constmnti*d in rock cut

the Hide walls ami invert- resting dirccfly on rock foundation.

-The vertical forces acting on the arch aection are the
rete section and the weight of the column of earth above

^m

m

482 A. \f ERICAS SEWERAGE PRACTICE

that section . P'or purposes of this analysis the weight of t he concrete section
can usually be omitted, for cases where the vertical load, or the depth of
earth fill, above the section is very much larger. Without material eiror it
can also be assumed that the vertical forces act through the center of the
axis of the arch for each section. The vertical pressure of the earth above
the arch is assumed to be the dead weight of the column of earth, in width
equal to the horizontal projection of the extrados section, and in depth equal
to the distance from the surface of the ground to the center of the extradoi
section of the arch. In case the dead weight of the concrete is used, this
can be added to the weight of the earth and the resultant pressure applied at
the center of the arch axis for each section.

The depth, vertical intensity, horizontal projection of the arch section and
total vertical load are tabulated in Table 150, Columns 2 to 5 incluaire.
/\J.su the vertical forces are shown graphically in their respective locatiou
in Fig. 186.

Horizontal Forces. — If we assume the angle of repose equal to 30 deg., the
intensity of the horizontal earth pressure will be one-third of the intensitr of
the vertical pressure at any point. The horizontal earth pressure is assumed
to act on a width equal to the vertical projection of the extrados section. The
values of the horizontal intensity of the earth pressure, the vertical projectiofl
of the arch section, and the total horizontal load are given in Table loO,
Columns 6, 7 and 8; and the horizontal loads are shown graphically in Fig.
186. The horizontal pressure may be assumed to act at the center of the
axis for each section without material error in the final results.

In Columns 9 and 10 are given the successive sums of the vertical and
horizontal loads, respectively, at each of the sections. These figures will be
used later in the ciilciilation of the moments at the different points.

The co-ordirijites of the center points of each section, x and y, referred to
the crown us the origin, are shown in Columns 11 and 12, and the values of
y^ in Cohunn 13. Column 14 gives the values of the differences between the
successive co-ordinates, as for example (jj — Xi), (js ~ Xj), etc., and C olumn
If) gives the difTerences l)etween the y L'o-ordinates in a similar manner, ad for
example (y^ - i/i), (//.i - 2/iO, etc.

landing Mofnmts. — The bending moments (all negative) shown in
('olumn 2 of Tabic? 151 are computed as follows:

f//i = 0

fHi = i/'i (X2 - X,) + hi (;/o - //i) = (1610 X 0.64) -f

(24 X 0.03) = 1031

I//3 = vii -f :^ir,u, - .f,) + r//2(//3 - y,) = 1031 -f

(3197 X 0.63) +(80 X0.12) = 3a>4

jfU = in,, + ^irjjA - X,) -f- ^//3(//4 - ys) = 3054 +

(4791 X 0.60) -f (177 X 0.13) =59.'i5
mj = 7>/4 + 2:?r4(x:. - X4) 4- ^fuiyi — yO = 5955 +

(()419 X 0.64) + (323 X 0.19) = 10.13^
vif. = m, + ^ir,(i,, - Xij + LV/i(//r. - 2/5) = 10,120 +

(S()35 X 0.62) -h (511X 0.24) = IS.ii'^
r//7 •= yfU + i;//v.(j-7 - xc.) + lV;r.(//7 ~ !/«) = 15,220 +

(9()G9 X 0.62) + (750 X 0.33) = 21,470

THE AlfALYSIS OF MASONRY ARCHES

483

ll

l*li

d d c o o "^^ o d d d ^ -^ -^ :*a CO

QC l^ O

r^ « c^

o o o

•^ oq C -^ N M r>- r^ t^ c& *o 00 O M *iS

d d o o o o d d o o o d d d m*

r-- c« cc

^ lO o

CO •-< "-H

I i I

f-* ^45 CD ^
^ ^^ iQ -f i-n

§(M.3Cf^^OO^<OCflQOSDQOC<0»C'-'«OaO'W fe

^ c o c^i »o 1^ ,-• ab to ^ CI <^l O ^^ ' C'l 'T '-; i> "^ , r^ f,^

i-k -* CO lo c^ ifs f^ '<*< "o S I r-i II
•^ 01 c^ c^ CI c^ , C*!

C^Ci-<!M"-rf'-C'^SaiOrtCOcOcOO[

dddoooi-»^»^wcO'^iot>^^;0'<!fiC'*oi;3lco ir

^ ^ *-* — *-^ ^ c 'I

Sao flO CO CO 1 PO S;
t^ iO Oi ^ O H

do— ^c^c^cc^'^ifljcDeDt'OCcaOQO «©eo^O

CI « t-- CI -* »o »o r^ 1^ o <o 00 '^ CO r^ i^ t>» i^ t^

rH CO u!3 ^* O -^ Ct^ <£3^ -t lO <--;_ '?9 '10 "^ '^ ''1 '^^

^ ^ i-T w" CO •**" «D x '^*' ?o <o d" tcT

o o o

^ooi^w^oiwocie^eoo^cb SB-^i^ci

«^ ^ f>-^ ^ o ^ CO ci T^^ q_ o o^ a?^ Ci^ 1^ Ci^ ^ oi_

-M 0^ -q^ o cc qT -^' CO to' r-' d '-•*' cf CO i^ ,^* qo cT

^PM^^^dCICICI ip-»

i I ! S * §

•J* tD t^ CO
d ift CI -^

QOGCq)a»fioeo^coi^^eoio

'^ooeOO-^Oeoigciu^wo
^^0IW^»O«DW^iOWC0

o o o

1H nM CI ^ ^

wKdoococat-osoc-^eooocooeg os
oo^-^cic<co*j'*ot^d5*-i*o*-<co CO

doodoocoooo»-I-^citf> ^

a^ a

CltiSOt^-^^OtOOb-Oh-COiaDOiCO

SO^.-4Clc0t0O00«-'»0Cii0'X
ooaOQOGCooooooaQoc^e;^*-*

jii'-^

;D »C 4/5 CO p «0 !"• CC' QC Oi O w 1^ *-• iX i«3 C *^ CI C^

tHIi-h^-ii— ii—if— (^H'pHr-<f-HCiC*^^*— '1-^

»0 O CO C^

=2 ill Hi

5

S

s

J^

s

s

g

n

CI

CJ

f3

g

g

1?

s

1^

s

g

S2

o

o

o

o

o

o

e

o

c

^

©

o

o

o

o

o

»o

fH

f-t *-»

cf cf Ci CI CI Ci C*!* CI* of Csf Cf Cf CI CO CO CO C« W CI CI

_ ___„ ^___ I t i I

c5*^cot5i^O'n'COio55<3if-^'^ ofl ; ;

c>i c« d ^ CI c5 c5 d c^i !N d CI tM CO » » : ; ;

•-•CltO"^tOOt-*QC^O'-^dCO^»^

to r-» ar cs

484 AMERICAS SEWERAGE PRACTICE

m^ ^ m: -^ Zvri^ - Xr> -h 2Ar<>* — yr' = 21,160 -h

ai;»9 X 0.«7; -r 10» . X 0.«) - ».-330

m4 = w, -^ 2tvX» — x<' ^ 2A< 'j^f — y^j — 20.590 -:-

(13,2W X 0.tf7:< -r ; 1475 X 0-51) « »^X-1«)
yii;i — TC} -^ Zt, X:i — Ti- -r 2A» j:.!— yv = 30.1-10 -r

^L5.I0r X 0.«7j -r 19T^ X 0.«2 = 50^-«S*>
«:: = »W:i -r 2t:i X;; — Xm. -r ZA-.ir^:: — ^-.i.i = 50.-I9O -r-

» 17.027 X 0.«0, - '2800 X OlSO = 64,J3CW

fl9.fl^ X 0.45) -r ^^0^2 X 1-01 « «lj»W
Wn = w.i -* 2'ri2'x:i — Z;z; -r Zkn^yu — j:;.' = '50-200 —

2Lrja5 X 0-». -r '«»7 X L20 * qi^^^^:^
'•*:4 = «.: — Zth'xh — X:i -^ 2A:i 7:4 — j^n; = 98J320 r-

22.S01 X 0.iO. -r *1« X 1.71 = 117.*-*^
M.i = 'n., — 2'f;4'-r:i — r;», -r 2A:4 ^n — y:«; = 117.940 ■*-

23.913 X 0.12; -^ >356 X 3.« « loL-^^^W
»»M = m:i ^ Z'rii'xii — z.i' -^ Zkn ^n — y-i,' = L51.430 -^

25.79* X - 2.25 - 14.»571 X 3.73 - l^. X^^»
m- = m:< — 2'rn x- — x.4 — 2A:4'>.r — *:«; = I4*-120 -i-

11.200 X - 3.17. - ' 16.471 X 0.7S^ « 125. 1 - '^
Wm = M:r — -V":? Xn — x- -^ 3A:r >:• — 5Fir' = 125.170 -r

>>140 X - 1^3 - 16 471 X a37i « 12L.^- ^
m;i = m;, -- 2 •.•:.* Xii — X:t — 2A:i y:» — »;« = 12lJ*75 -^

2920 X - 1.0^ - 16.471 XO.20; - 122-Ol^

T.\BL£ 151 — BE.vi>rxG MowE.vT*. Thbusts A3n> Shkaks. Ca5C ^

Ar_u>*u» -f :>?r. -w.^ r I>^v2-j- H-.r»'^fcc<t ^»>w*g br EL— de Theory .—

^

'>

14^

-•=/->^4

14..>5«>

-0 45

1.1*>

■>

-I.'Xii

-41

.><3

-.!;.'>»

14.720

-0.41

L53*

•*

-/iAvt

-4S'>

2.ViO

-0.714

14.990

-0 3S

2.0tt)

4

-.o.:-.'o

- 1.72i>

4.223

-4.7'»

15.400

-0 31

•>.w

-J

-r.rlji.'

-4.^/.»

^.'>»

—i.-Vr^

15.^*}0

-0 21

2.900 i

'j

- l:.22»v

- lO/^/t

10.4'>'J

-1.7i>S

l'>..>30

*0 10

3J900|

-•

-2!. 47'.

-22.>4^>

lo.2>J

*2>>

17.330

-0-01

3.500 ^

i

-J-'.^y.'

-42'*2?.i

21.110

-I.>^2

1SJ210

-0 11

3.600

'>

-•''.14-..

— 7'. 71'''

2'»..*-4'>

-4.Ir.2

19.330

— 0.22

3.500

' 1^'

-.V;.4*'

- l-y'.v.y'O

.>7..>7m

-6.4S2

•3:».500

-0.32

3JM0

: I!

--A ■'^>»

-J!7.4-»

4'.22'.»

— S.^72

2I.N50

-0.40

2.6O0

1 /

— •*' .' -T • •

-.:^:2.i>'

rr.'.;.:-/)

-•:*.v>2

2.3.210

-0.42

1.300

1 W

- '*^..>- •

-*>.-y>'

<1 710

-'>.172

24.300

-0.3S

550

\ 14

- I i 7 •*4^ •

— ^71 »^'«'>.

: 7.'iio

— 3.S*^2

24.500

-0-16

3.-20n

I.-

-1.'-: 4.>.

— !.»-.7.i;.>"«i

!'/••- iO

-I* "-IS

2-xSOO

-0-62

THE ANALYSIS OF MASONRY ARCHES

485

put-atioiM for mil to fin 1 1 are for Case IL

The fufljmntions wt + tr, + u'l and hi + /u + /m, etc.» are taken from
'^-''^luitiiiji 9 and 10, Table 150. The diffc^reiioe between the x and y co*
tmt<vi, an (x^ — xi) and (|^a ^ yt)| ore taken from Coliinins 14 and 15>
_^ t^rtivi'.l>% fjf the same table.
* rmctnat Cfo\im,—Th<^ next step in the analysis is to find the crown thruHt,
"i«*h fan be obtnini^d from the equation previoiiJ^ly given, llie values uf
^^^ Xm\t, 2^ and 2^//* are given in Columns 2 and 3 of Table 15 X and
^'olum,ia 12 and 13 of Table 150,

wSmy- ZmZy 15( - 3,<^63,Q46) - ( - 68S,230 X mm)

40.63- 16 X 254.23

Hm = 14,502 pounds

111 the above equation n =* the number of divisions in the half arch
ion^

hn bentUng moments at the crown can also be obtained by the equations
"^"©ady given, as foIJowa:

M. -

Zm -f //.r, - 688,230 -h 14.562 X 40.63

Af , » + 6438 ft.-Ib.

15

*th» values of the crown thrust Ho multiplied by the values of y^ are com-
'Ut«d and tabulated in Column 4, Table 15L

FVom the data thus obtained the total bending moment for each aection
> Domputod from the formula given hi a previous paragraph, as follows:

XS = M -f M. + H.y

Ml « mv -¥ ^U. f H.yx = 0 -f 6438 -f 146 = -h 6584

i^f » mi + Af* -f H^Ui - - 1031 + 0438 + .S83 = -H 5900

\ The resulta arc reoordcd in Column 5 Table 151.

IXa^^aw,— The value of the thrust and shear at any pomt can be
ned fn>m the foree diagram by graphiiml methtwls. As a nile.the shear
»fer arehett can be neglected* The value of //<, «= 14,562 lb., the crown
'iTiijit, u firnt laid off to senle on a horizontal line, as shown in Fig. 186. At
l*ft end uf this bne, lay off to scale the vertical force w^ vertically down-
•"ftfil. and at it* lower extremity lay ofT the horizontal for(«? Ai to scale hori*
|t ' ill* right, A b*]ic drawn to connect the right hand end of hi with

1 of ici is equal in amount, by scale and direction, to the result-
r**** < »rec Pi acting on the firjtt section of the arch. A line or **ray "

dtii . ii^ right exiri'mity of hy to the right extremity of the horii^ntal

^^^ If, Of origin t i*« equal in amount, by scale and direction, to the resultant
c, Ru between sections 1 and 2 of the arch. At the right extremity of
* off Wt vertically downward and then Aj horixontally to the right and
for each successive vertical and horizon tnl load acting on the arch.
[tke Itrokirn line tbun formed is culled the **load line/* Tlu* resultant ex-
I foreB octing on encli serf inn i»f tlif ;irch rjin be obtained Jis above, and
remliant pressure acting Im lutrn the seclious of the tirch. The

AMBBICAN SEWEEAOE FRACTWB

normal or true thrust is obtained by resolving tl\o force /J parallel and nor
to the arch axis at the point in question. These are shown by the dolK
lines on the fon^ diagram, Fig. 186.

EquiUhrium Polygon. — The equilibrium polygon, or diagram showtDg 1
line of pressure on the arch, is drawn by the aid of the force dingrnnu
crown thrust acts for a aymmetrically loaded arch in a horizontal ihrc<*tia
and the puint of application is at a distjince above the axis of the arrh &t t
crown equal to M^/Ho = <?, the eccentric distance, if Mo is plus^ and I
the axia by the same amount if M,. Ls minus. For the example at bAQd

-M4S8
14,562

= -h 0^442 ft.

This distance ia then laid off vertically above the arch axis at the <
and the resultant crown thrust is drawn through this point to its intersect!^
with the resultant external force acting on the first section of the nrt
From this point of intersection draw a line parallel to ^i, taken from i
force diagram, and prolong it to an intersection with the oblique force ii^ti
on section 2 of the arch. In a similar manner continue by taking the *'m)t
from the force diagram and prolong each to its intersection with the uexX <
lique force acting on the arch.

The intersection with the first joint of a line parallel to Ri from the foJ
diagram, gives the center of pressure on that joint, and the intersection
^3 with the second joint gives the center of pressure for that ioint» and «> ""
for the other joints. The broken line thus obtained, passing down !l
the arch section, is the **line of resistance," or the ''line of thrust'* 5
arch. The amount of each thrust, that is, the true thrust normal t^ tit
section (for practical purposes, the total resultant pressure, may o(te^ *^
taken as the normal thrust without serious error) should be scaled fi^
the force diagram and the amounts recorded in Column 5 of Table I5l*^

The eccentric distance, c, is found by dividing the total bending momwit^
the thrust, and is recorded in Column 6 of Table 151.

p\ir positive moments, and therefore positive values of e, tjie line of tJtntf*
liejs above the arch axis. The amount of the eccentricity is shown grap '
on the diagram of the arch by the dist^mce from the arch axis to the i
application of the tlyust, which is the intersection of the line of pressn
the plane of the section. After the line of resistance or equilibrium p'
has been drawn, the computed values of the eccentricity can bccheri
scaling the values on the equilibrium polygon. While it is not nece>
draw the **line of resistance'* or "equilibrium polygon'* in order lu •
the fiber stresses, it is usually well to do so in order to check Um aljc*-'
work.

It should be borne in mind that 1 f
true line of resistance, A« ffic nu^ , ,

creased the cquilibriu i appron

is a curve* Thr » v i '^'^^^^^^^^^^

the ATdli axis aii ^^^^^^^^^^fc. <ll

to the

porpor

THE ANALYSIS OF MASONRY ARCHES

487

ft wiQ be iJDt'Cd that in the analysis under Case II the difference is more
noticeAblc near the tnise of the Ride wall and in the invert.

ilysis of Case n* — In the preceding analysis, the invert of the section
__ J curisideiTd as sopMrtitcd from the side wall, but in this analysis, under
CW 11, tbt? entire sinictitre will be analy»ed. The same aa^umptton, as to
vertical .-md horizontal ftirees acting on the arch and side wall are made and in
wlfiitjon it is assumed that there are vertitsal forces acting upward on the
wiviTt equal in amount to the total downward vertical forces, and uni-
formly distributed over the invert, *See Fig. 186. The upward vertical
faf<x? acting on block H3 is combined with the vertical (downward) and hori-
iDQttl components of the e^rth pressure acting on the left side of the block
pfodui'iiig the oblique resultant force as show^n,

Ihmnon of Axis to make ds/I Constant. — The chief disadvantage of this
iJt^thod m applied to Case II lies in the necessity of dividing the axis accord-
i^'f to u prescribed ratio. This usually requires e^irefid manipulation and
' "ated trials to subdivide the side wall and invert in order to obtain suit'
If if divisions. It can be done as Fig, 186 shows, and in the example at
^«d no great difficulty was experienced. Blocks 15 and 16 are, however,
•fmievrhat larger than is desirable for sections where largo thrusts, bending
''Jomenlii and shears occur.

The nicthixi of dividing the axis is the same as described under Case I.

C<mpnUti\on9. — ^The remainder of the computations are made in the same

for Case L New values of //«, Mo and e are computed, using the

►ris from division 1 to 19 inclusive instead of from 1 to 15 inclusive as

^ i« L For convenience the values for points 16 to 19 have been included
'' U the others in Table 150, The computations of the bending mo-
"•iftnti* for joints 16 to 19 were given with those arising under the assumptions

Xer values of //,, M, and e are found from the formulae as before/using
nmntions from divisions 1 to 19 innlusive, as follows:

*» X »Ti y » ZviZu 19(- 12,009,546) - (- 1 ,205,4 14 X 103,03)

- - nZy^ " 103.03* - (19 X 1228.73J

^ H 170 lb,

_ 3gm H- H. 2y [- 1,205,414 -f (8170 X lai.Oa)]

n " L 19 J

-I- 19.140 ft.-lb
M. 4- 19/140
it. " +8170

^\\\\ iho above values a new force diagram is drawn (Fig. 186) and a new
ill polyieon in the same* maancr as for Case I.
11- ■•'■'1^ for the bending moments, thrusts, shears and eccentric
in Tttble 152.

' wo equdibriuni polygons or lines of resistance for
Illy how the bending mumenta are greatly increased
vert iis |)art of the elastic structure,
1 11 1 and point of application of the normal thrust on
ctiuri uf Uitt arch, the resulting fib^r stresses can be readily

= + 2.34

488

AMERICAN SEWERAGE PRACTICE

computwl.

The method of making these romputations will be deecribed

Table 152.— I1j:\

Anulynis of 15-fl

DING Moments, Thrusts and SircAiia. Case II

1

2

:i I ' 1. 7 1 « 1

■^n.

Bp mil nil

Totnl

l>rPOtricl

tion

motiietit4

my M^y booiliug

TklMl^l^

'i>-^ * flhtfinn

m

moment, M

.:nu.'.^ 1

I

0

0

82

19,22J +2 35 1,300 |

2

-1,031

-41

327

18,43fi , ' +2 20

2,250

3

-3,054

-489

1,307

17,393

8,700

+ 2 00

3^00

4

-5,955

-1,726

2,370

15,555

9,210

+ 1.69

4,200

5

^10,120

-4.860,

3,920

12,940

9,870

+ 1.31 5,000

6

- 15,220

--10,960

5,880

9,800

10,670

+0.92 '5300

7

-21,470

-22,540

8,580

6,250

11,680

+0 535|6.60O

8

-29,530

-42.820

11,850

1,460

12,920

+0 11 7,200

0

-30,140

-76,710 16,010

-3,990

14,400

-0.28 l7,r\f>0

10

-50,400

--130,300 21,090

-10,260

16,070

-0 •

u

-64,330

-217,400 27,610

- 17,580

18,030

-0.:- . ^

12

-80,200

-352,100 35,880

-25,180

20,120

•I 25 1 6,1150

13

-98,320

-558,500 4(i,40O

-32,780

22 J 80

- 1 48 {5.600

14

-117,940

-871,6rXI 60,380

-38,420

23,670

-1.62 3,200

15

-151,430

-1,673,0<K» 90,280

-42,010 ;25.794

-I 63 6,500

16

-148,120

-2,189,200 120J50

- 8,230

10,600

-0.78 [9,100

17

-125,170

-1,947,600127,130 1+21,100

9,400

+2 -

18

-121,875

-1,941,500 130,150

+27.415

8,660

+3 i

19

-122,019

-1,908,200 131,780

+28,901

8,200

+a.5^ 7^

*

-1,205,411

-12,009,546

- Zm

- Zmy

"

i

ANALYSIS OF ELASTIC RING BY METHOD FOR IN DETERMINATE

STRUCTURES

If the Bcwer is conatructed m earn pressi hie soil or under ttfi> 14

where it is not fair to assume that thy onds uf the riroh iirc lixrfi, ,|«f

sewer section musit be considered as an elastic structure, «i»bjccl to tk^
formation.

The determination of the line of resistance is based on the mot bod fur
coniputing statically indeterminato stresses in an elastic struct "'^'^ «^

method has l>een ably discussed by Prof. (\ W. Hudson in his *M 1^

and Statically Indetenninat^ Stresses,** 1912, on whirl
cuasion has been based. The authors desire lo ticknowlt '

Arthur W. French, I*rofes8or of Civil Engineering, W^
Institute, in applying this method to the analywis of wi
preparing the fullowirtj; not^s and eotuputation^. In aniUyxing the aeetkm
two cjvaes are considered.

Casi* L^ln tltis ca4»e the ehiiStio defornt»tion of tha wholi! irwcir Hoc it
tiiken into accoant. There is no aflaumption that the endu iin> fixecl, for ibc

"TMS ANALYSIS OF MASONRY ARCHES

489

taken symmetrically on both sides of the center of the invert is
1 upon by dirpdt stresM^s and bendinif nionienta (see Fig. 187). ITie
^ndy i»*vUon, instead of actiiiR tuM n cantilever beam, tis in Fig. 185, aet« like
ring^ Fig. 187» Vertical and horizontal earth presaurea are aa-
lact on the serni-eireiilar arch and sitle walls ami the upward pres-
»on the bottom is axsumed to be uniformly distributed over the bottom
f iiiid eqiinl in total amount to the sum of the downward vertical forces. Such
• distribution of the upward forces seems to be a reasonable assumption if the
«!ww is construeted on yielding or compressible soil, and at any rate it im-
poip^ mare severe conditions than the assumption that the ux^waxd forces ore
fili<tnbutcd with greater intensity near the side walls.

Cbift n.— In tbi« case the same assumptions are made as to vertical and

hatiiotitJil turih load« on the semi-circular an^h and side walls, but the invert

( oooitidi*re<l as 8Cparat<?d from the side, possibly by joints at I he junction of

. Hud side. The invert server only as a tie or strut to spaw the walla

nd Cftrrieji none of the vertical reaction. In thi» case the ehihlic dcforma-

Irjti of only the ttemt-eircular arch and side wall is considered. This method

ame in th«*ory nn the analysis far the elastic arch previously given, but

\ in method because In the latter, the arch rmg is divided so m to make

490 AMERICAN SEWERAGE PRACTICE

ds/I constant, while the method described in the following pages makes no
such division.

There should be but little difference in the lines of pressure ftrom the method
given by Tumeaurc and Maurer and that described in the following para-
graphs. Some differences occur due to the approximations used which might
be eliminated if greater precision was justified. The results are sufficieDttf
close, bearing in mind the uncertainties of loading, earth pressures, etc.

Case 1. — If the sewer section shown in Fig. 187 is cut at the crown by a T)9-
tical plane, the structiu^ may be considered as a curved beam acted upon by
the known external loads and the unknown forces, //», V* and Af .. If then
three unknown forces are determined the resultant force acting at any section
may be found, either analytically or graphically.

Let Ho = thrust at the crown (Fig. 187).
Vo = shear at the crown.
Mo ^ bending moment at the crown,
m » bending moment at any section center due to the eztenil

loads on one side of the section, the ring being considered

as a curved beam; negative in sign for left-hand half of

arch.
AT, F, and M » thrust, shear, and total moment at any section center.

ds » length of a division of the arch ring measured along the

arch axis.
/ — moment of inertia of any section, determined at the center.
w, hf P = the vertical, horizontal and resultant external forces,

respectively acting on the sewer section.
R = the resultant pressure at any section.
X, y =» co-ordinat-es of any point on the axis of the sewer section

referred to the crown as origin. ^VJl considered as positive

in sign.
rtiy = moment at any section due to 1 lb. acting vertically at 0.
nix = moment at any section due to 1 lb. acting horizontally

at O, the crov^-n.
diy = vertical deflection of O due to 1 lb. acting vertically at 0.
diz = horizontal deflection of 0 due to 1 lb. acting vertically

atO.
dio = angular change of face at 0 due to 1 lb. acting vertically

at O.
dty = vertical deflection of 0 due to 1 lb. acting horizontally

at O.
dts = horizontal deflection of 0 due to 1 lb. acting horizontally

at a
dto = angular change of face at 0 due to 1 lb. acting horizontally

at 0.
diy = vertical deflection of 0 due to 1 in.-lb. bending moment

atO.
dsx = horizontal deflection of 0 due to 1 in.-lb. bending moment

at 0.

THE ANALYSIS OF MASONRY' ARCHES

491

dtm — aftguhir change of face at O due to 1 in. -lb, bending

moment at O.
^g « vortical deflection of 0 due to external forces*
A, = liorizontal deflection of O dtie to external forces.
Art «- angular change of face at O due to external forces.

A»ume deflections to the right and upward as having a positive sign, and

eflrcttons in the opposite direction as negative. Assume that revohitions

angular changes of face at 0 in a clockwise direction have a positive

fJ'^^fuations, — From the fact that the vertical, horizontal and angular
Si-^ctjon of the right and left faces of the crown joint must be identical,
three following equations can be derived.

1^ » 4- VJitf + H,dt, -f M.d,y = « a,, - V^i^ 4- ff</hM + ^^^'U,

— H^u - M^u^ = ~ A« -f W,d,« -f M^u,

>m the first equation we obtain V<, - 0 and on that account it has been
littc<| In the second and third equations.
From the second tind third equations the following values can be obtaine^i:

„ A ttrftr — A ,cf|tt

M. =

dtadu — d»*di«

A^djxj^ A gdta
dtmdu — dtidu *

1 Considering only the deflections needed for the solution of equations for
!• and M^^ their values may be computed from the formulas:

A^ = Z w

El'

t^ken 0,8 ^ Z m

dM

A# = 2 mnts ^ taken as =* S mmtrr

di

d$

*fu - r

El

'EI
taken as

taken aa « 2 wt^-jy

a*, « Zm^^pY taken as S «i# ^i
*«ew r = thickness of masonry ring at the center of any section.
M - m + .V, -f H^y

«*J the ftbiive fomiuks for i/» and 3/, each expression represents the sum-
-AU.r, ,,f ^jjjj valuee indicated for the several divisions of the axis under
U(jn«

i' kHS the factor ! / 12 in the moment of inertia, /, is omitted
( all terms; also the ijoefficient of elnstidty, E, as shown in
tiiitted us it is cormtant throughout*
^^n. — The first step in the analysts is to draw the half

492

AMERICAN SEWERAGE PRACTICE

sewer section to some convenient scale of suitable size to allow the scalii^
of various dimensions and forces without causing too great an error. Thi
section is shown in Fig. 188. The center line of the section, shown bv th
dotted line, is divided into a number of divisions which, for oonvenioifl
may be approximately equal, although this is not necessary. The sectia
shown has been divided into 13 divisions. By this method it is not neeei
sary to subdivide the arch axis into divisions so that ds/I shall be oonstan
as in the method previously described. This has the advantage of allowii
the side wall and invert to be divided into sections convenient for oompot
tion, and especially at the junction between the side wall and invert it miiki
it possible to determine the bending moment with greater accuracy.

Computations, — The radial thickness of the masonry ring at the center i
each section is then scaled from the drawing and recorded in Column 2 (
Table 153. The cube of the thickness for each section is recorded in Colum
3 and the length of each section measured along the axis of the arch is n
corded in Column 4. Column 5 gives the values, for each division, <
ds/t^f which is equivalent to da«.

In Columns 6 and 7 of Table 153 are given the co-ordinates of the oente
point of each division, the x co-ordinate being measured horizontally frtn
the crown and the y co-ordinate being measured vertically from the center o
the arch division to the center of the crown joint.

Table 153. — Computations op External Forces and Moitcnts

Analysis of 15 ft. 6 in. X 15 ft. 2 in. Horse-shoe Sewer by Method for IndetenniaiW

Structures

1

2

3 . 4

5

6 i 7

8

9

10

11

Sec-
tion
No.

Thicknt'SM
of ring at
conter of
section t,

ft.

O.O.'i

1
/», 1 d8,

ft. ft.
0.8043 2.21

ds
— >

(dta).
ft.

Co-ordi-
nates of
center of
section
X. ft.'y, ft.

mx - y
X 1 lb.
ft. lb.

0.08

(m,)«

d»
0.018

'„ » III
0 22''>

2.7481.09: 0.08

0.0004

0 . <).-)

O.S.''>73;2.21

2.578 3.18 0.62

0.62

0.3844

0.991

l.59>

l.O.'J

1.01)27,2.21

2.023 5.09

1.70

1.70

2.8900

5.847

S4,)T*

1.13

1. 4421), 2. 21

1.532 O.ftS

3.20

3.20

10.2410

15.688

4 l-C

1 . 2'A

l.S00>>'2.21

1.187 7.7r>

5.08

5.08

25.8030

30.6:k»

t) Oo>'

1 . 'M\

2.5ir)4 2.21

0.878' 8. 36

7.17

7.17

51.4090

45.140

6 W

1 . 57

3.S091) 2.02

0.522 8.46' 9.28

9.28

86.1180

44.950

4 M4

1 . US

7.7>i21 2.02

0.260J8. 48 11.30

1 1 . 30

127.6900

33.200

2 1«.>

2 . .^r,

1(1.7772 2.02

0.120 8.48 13.32

1

13.32

177.4220

21.2«.)0

I 5-^

11.848'

1

197 . 754

31 vM

10

1 . •) 1

7.3014 2. IS

1 '
0.21»U 7.43 14.59

14.59

212.8680

03.650

4 36.?

11

1 r>2

4.2r)i:) 2. IK

0.513 5.32 15.07

15.07

227.1050

110.500

7. 73 J

12

1 . 3.-)

2.4004 2. IS

0.886 1 3. 20 15.55

15.55

241.8020

214.250

ISTH

i;i

1.0")

l.l.")7«i2.1S

l.SS3,l.07 16.03

16.03

256.9610

483.860

30. 1«

15.429

r

1.076.014-

g7.K]

In Coliiitin S aro ^iviMi values of nis, the moment at each of the aectioi
due to a for(HM)f 1 Ih. acting liorizontally at the Grown, This is eqamknt
1 11). multiplied hy the // co-ordinate at each oentor point* OohnuiQ^

THE ANALYSfS OF AfASONRY ARCHES

493

d$

ilues u( ntt^ and Coluiim 10 the vjsilues of m** — » wliich will be required

' for the values of d^

Column 11 gives the values of m« — r which wiU

'a

I the vahics of d^^ and its r<|ual, dx^,

nal Forcra,^ — Table 1»54 shows the computations for the external force*

ch arc made in the same maimer as the computiitiona for the vertical and

[>ntal forces described under the analysis of the elastic arch (see Tabic*

The sew^cr seation shown in Fig. 188 is the same section that was

for tlie analysis of the elastic arch shown in Fig, 186. The depth of

Jx ftJJ over the exirados of the section at the crown is assumetl to be 24

[the unit weight of earth being 100 lb. per cubic foot and Ihe angle of

9L% 30 deg-

I the method of eoni puling the data given in Table 154, has already been
bfiiOy explained it will not ]»e repeated here.

t4nnpuiat\on of Partial Bt'iiding Momenta. — ^In Table 154, Column 11, are
the values of the differences of the co-ordinates, as for example,
' jTi), (xi — jFt), etc. Column 12 gives the differences of the y eoHDrdinates.
amn 13 show^s the bending moments (all negative) of the external
Is con>putcd for each section as follows:

« 0

- tt^ (xt - xx) H- hxiut - 1/1 ) - (5.475 X 2.00) ^ (224 X 0.54) = 11,563

- m, -h r«^(j» - X, ) + £A,(y, - y, ) = 11,563 +

(10,725 X l^^l) -h (912 X 1.08) = 33,033

- mi + StPi(r4 - ii ) + Zh.ivi - yi ) = 33,033 ^

(15,465 X \M) -f (2,067 X 1.50) = 60,723

* m« + 2iP|(zi - 3F4 ) H- rAUl/* - ^4 ) = 60,723 +

(19,445 X L08) + (3,682 X L88) = 88,645
-- W4 + Str*(xt - Xi) + 2/;*(y« - yt ) = S8,645 -f

(22,335 X 0.60) + (5,752 X 2.09) = 114,060
= m. 4- 2:w^fl(j'7 - ^t ) -K £/u(i/r - V*) ^ 114,060 +

(23,725 X 0.10) + (8,192 X 2.11) = 133,717
= mj 4- 2titT(x, - j-7 ) + S/*T<j/t - yi) = 133,717 +

(24,535 X 0.02) + (10,552 X 2.02) - 155,527
= OTi + Xw%{x% - x» ) + SAi(//» - yi) == 155,527 +

(25,392 X 0) + (13,172 X 2.02) - 182,137

* m, -f SttJ.Czio - ^» ) -f 2A,(yio - l^» ) = 182,137 +

(26,447 X - 1.05) + (16,512 X L27) - 175,339
= mjo + St«io(^ti — ^lo) -I- 2/i|o(|^u — Vio) - 175,339 -f

(17,747 X - 2.11) -f (16,512 X 0.48) « 145,815
_= «wn -f Zwn(in - xu) 4- SAiid/is — yii) = 145,815 -|-

(11,987 X - 2.12) -f (16,512 X 0.48) = 128,331
iu -f 2ttf„(x,, - x„) + Zhii(yit - vit) = 128,331 +

(6,197 X - 2.13) 4- (16,512 X OM) = 123.057

K- 1 ituies of the moments given in Column 13, Table 154 and
lifttji in Columns 5 and 11, Table 153, the values of A<a and A^ shown
olamaf 14 »ad 15, of Table 154, can be computed.

494

AMERICAN SEWERAGE PRACTICE

-€!•

6 S

6 3

2 sllls^a

00 «

w s g g; e C
c< o -^ 5 ^^ 5
to ^ e& 40 o^ r^

.^ !N W5 (>. ?0 ^ W

O 52 2

CO CD 9)

CO S

C^ o

_ "^ 00
"? Q O O ^*
O O lO '^ N

S o '2^ 56

iQ t* i3t V

?0 M S «

i^ ^ t- r-

W9

o w r^ c^ io o r-* t- t-*

SCO M ^ o -^ M CO

q^ is^ <c o^ »^^ «^^ -^^

*-r c5 Q oc ^' « i^ ^^^^

o »c o o
w 3 o o

^ *. '^ *■*
u3 i>^g

^ UI5 ^ h*

:CC ^ C^ »0

CC OD rQ O

OO 00 QO

^ ^ 1^

o -*' ^ ^ <N d c^' ri •^'

d d d '

§S§§g2g8S

1

S 2 C *

w cs c* .

1 t 1 •

« CO uf cxf o" w' ^"

2 22 •

U3 «C c» .

2 JO 2 ;

» 8.
§1

\iA

t^M:0"^COC^C0Ci'-f

a A C

N 25 *^^ ^_ o_ '^^ CO o 50
*»^" -< m" c^' o* ^j* CO

MobeoQOi-iro^c^^

O o ^^ ^ Csl CI CH 04

1111 11-:

t"*" O l^» PO ^ ffO © 1^^

OOOOOOCSO^i-'lM

1^ r^ h.

KS2,

I iV?£

Ui iti ^ 70 C^ ^ ^

§S8g

r^ w r, ^^

^ iO «3 O

a?'^f ^f-

w « ^ ^ d d © d d e^ c4 et et

ntii^t

>.2 o a

:^ ?

csT c4* e^ ci" ci to" CO co' co

8 o S

I

1^

C^NC4^iCI«OCOCOC0

THE ANALY\SIS OF MASONRY ARCHES

495

Thrust, — From the dnta at hand it ia now possible to compute the
f //^, the crown thrust, from the formula previously given,

A, du - ^Mdia _ (l/)0Q.14O X 87.921) - (10,453,553 X 15.429)
dtadu - dudu " (87.921 X 87.921) - (1076,014 X 15.429)
+ M^

tni at ike Crou*n. — The moment nt the crown , Mtf, can also be oom-
rom the formula already given, as follows:
A*<it.^_Ax(/«. {1,000,140 X 1076.014) ^ (10,453,553 X 87^)
d,adt, - d^dt^ ^ ' (i5.429 X 1076,0 14J - (87.921 X 87.921)
► + 17,700.

Uncity at the Crown. — From the values just computed the eccentricity
, c, can be obtained as follows:

E - M^/H, - 17,700/8,260 - 2.14.

positive in sign, the value of e will also be positive in sign and the
, € that is, from the arch axia to the point of apphcation of the crown
should be measured vertically upward from the arch axis. If, on
nd, the value of Mo had a negative sign, the corresponding value
trie distance, r, would have a negative Hign and the eccentric
should in that C4i»e be measured vertically downward from the
xis at the crown.

total bending moments , M^ at each center point can now be com-
from the formula

M = m H- M. -«- H.y
ict should be bnme in mind that for the left half of the structure
»lf considered in this analysis) the values of the bending moments,
ibftve a niigattve sign.

JfcBLE 155. — Bexdixg Moments, Thrusts and Sbears — Case I

ATuily«lfi of 15 ft. Q in. X 15 ft. 2 in. FIorse«hoe Sewer by Method for
IiiflrterniinntH Structures

^

^

4

5

0

ToUl tMynding

Thruatu,

E«(MMitrlo

Shejiri,

bo

tKv

mometit». M,

AT.

dtatiiQctea, #,

y.

.

ft, lb

ft. lb.

lb.

ft.

lb.

Q

17,70<J

'

660

18,360

8,670

+2 U

4,400

5 J 20

11,257

10,750

-hi 04

7.200

11,0^30

- 1,283

14,200

-0.10

a,6oo

26,410

^16,613

18,000

-0 93

8,500

4r.9lK>

-28,955

21,400

- 1 36

6,750

59,200

-37,160

23,4(X>

-1 59

3,700

76,650

-39,367

24,600

-1 60

2,300

«>a,400

-44,427

25,400

-1 75

6,000

no,orK)

-54,437

26,450

--2 06

8,250

V2o,rf(Hf

- 37, 139

12.100

^3 rj8

15,600

I2j,)rw>

-3.615

10,800

-0 34

9,850

1

i2H,:j(H}

-f 17,869

9.480

+ L87

4,200

J32.4<>0^

+27.043

8,100

-f-3 33

1,800

dfa

496

AMERICAN SEWERAGE PRACTICE

brfom

Column 3 Table 155 gives the values thus obtained.

Fitrc*' Diagram. — From the data at hand the force diajEtram csn'
structed in the same manner as described under the analyflis of thi
arch. The stress at the crowTi, /f o = + 8260, h laid off on a horixoi]
as shown in P'ig. 188, and the load line of the external forces ooaa
from which the values of the thrusts can he obtained The valufl
thrusts are entered in Colunui 4 of Table 155.

EqtntibHum Polygon, — The equilibrium polygon can now be coni
in the same manner as described under the analysis of the eliwfc
The crown thrust is located at a distance from the axis equal to the o
distance already found, or 4-2.14 ft. This distance is laid off ?(
upward from the arch axia at the crown and the crown thnjst is a
to its intersection with the iirst oblique external force acting ou a
of the arch. The remainder of the polygon can be constructed in
with the analysis of the elastic arch already described, Refcrrill
it will be noted that between sections 9 and 10 the equilibr
doubles back on itself. This is of no particular importance^ but is I
be confusing unless special care is taken in scaling the eccentric d
itom the axis to tho correct lines of resiatanoe. If the line of the equ
polygon from one external force to the next is followed in logica
thcrfi Hhotihl be no trouble. A different arrangement of the divisw
combination of the external forces acting on sections 9 and 10 wou
tic-ally eliminate this peculiarity without changing the locatioiLJ
in the remaining sections.

It is interesting to note that the line of resL^tance lies on
mason rv* section for almost its entire distance^ and at the invert il
siderably below the section.

As previously stated, it Ls not necessary to draw the eqiiiUbri\iin
in order to obtain the stresses at the various points in the section,
usually advisablt* to do so in order to obtuin the advantage of chcd
algebraic work by scaling the eccentric distances from the dia^
comparison with those computed and recorded in Column 5 of ,
If these distanoeSj or any one or more of them, do not check witi
acc\iracy, the computation should be inspected for possible er

Computations for Case n.— In the figures usetl for Case I th©|
included sections 1 to 13, inclusive, while for Case II the sumn
include only sections I to 9 inclusive. For Case II new vaJu4
crown thrust, and aU©, the moment at the crown ^ iirc comput
figures for sections 1 to 9, inclusive* These new eomputattonfl »]
below

A^d>, - A,dt^ (627>455 X 31.864) - (3,078,253 KM
dt^du - dud%^ ^ (31.864 X 31.864) - (197J54 Xj

H^ = + 14,810.

A.(/,^- t,di. (^527,1

^* " rfi^rf,, - d„r/,. * n 1 >

JIf . - -f 4,680.
The new eccentric disUirH-c i^* <m>i;h *J^:',

riony

H.

lOk

5t>

X'.

(I

\'^

oa

L

ymA\:i hj^ inii'V^*^-^ -^ ^"» ^

0O3d OOOfOOO

folk tllll6tk\X5lliliK ^>

ii!»UT4ft >Jitniiifisi9h(ii In lMi4M<t

edl(HS8%Hl

s^

M10l3Mw,>f

r^vmt

:M,tm,

\ ,

I5.*»i?l

,t>«^'^WV

'I—

1^1

-Alf^

t

s

1

VHi

toiMoa.

Vf

A«

I .ort

Q»»

THE ANALYSIS OF MASO\'HY ARCHES

407

Tahlx 156, — BsKOj^fG Moments, TimusTs ash Bueab» — Caj^k 11

Au»tyata of IS lU 0 in. X J5 ft. 2 in, HoraeHihrnt 8itw«r by Method for

1

i

3

1

:,

1,

Tiitmt headititf

1 l^riiht-,

|'>r<'titrir

Nlj->;iT3,

tS^Uoa

»^.

momcQU.

A\ 1

di«t»DC«tt, «,

r,

ft. m.

ft. lb.

lb.

fl.

lb.

Crown

-f 4.680

14,810

-fO.32

1

1,180

-f hfim

15,120

-fO.39

3,500

2

9,190

-h 2,307

16,8b0

+0.14

4,700

3

25,190

- 3,163

19,400

-0.16

4,650

4

47,400

- 8.043

22,000

-0.39

3,300

6

75,:iOO

- 8.665

24.000

«0,36

750 :

6

100,200

- 3,1S0

24,400

-0.13

2,800

7 1

137,400

+ 8,363

24,535

+0.34

4.200

8

167,400

-f 15,553

25,390

+0.65

1.500

9

197,:{(XJ

-1-1(1.843

26,450

+ 0.75

1,700

A new force duigram can now be conatr acted , ufsing the stirne loud line

n» htti%r%* Ht"»j Fit?. ISS. The horizontal distance //„, or thrust at the crown,

I II 'rent itnd on that account the amount and directioii of the rays

Krom the new force diafo'am another equilibrium polygon can be laid out
cm tbe maaonry section, na fihown in Fig. 18S, the dash line being the Uue

* Unqifucftnaf

j 1 boftom to Bi "at^o^ SpnfHjt'nq LingfOQfoC

^- i L&rf^. &&rj 2// C to C

0 I

3 4
•* 1

189, — Cracks in sewer nrch cauac<l by cxceasive loading.

'»r equilibrium polygon for Cti^e II. while the dot and daah
mihbnum polvuon fur Case I,

i»e two lines of remstance, as showing the

Mipi up in the maaonrj' section, cm account

I I ,-suiiiptiuJi of the action of the nianonry invert. The

M i , 1 11 9 section, where the sewer in constructed u& a monolith

lea

ifarihi

498

AMERICAN SEWERAGE PRACTICE

from invert to crown and the invert rests on compresaihle soil, af» mii
higher and more severe in both the crown and invert, spe*
nnd even in the side walls than in the case where the side wa i
on ledge foundatioru

Experience with Lofge Sewer Section.^ — A few years ago the atteniioiK
the authors was called to the actitm of a large horseshoe 8ewf»r
which had cracked in the arch, Fig. 189. This section, although «ti^tj
smaller than the seetion analyzed in the foregoing discussion^ w»8of
ticftlly the same type and was constructetl t%& a reinforced concrete mooo^
lithic structure, on compressible soil. It will be noted that the iirch cT»ckni
as might he expected from a study of the line »»f resistance for Oise I, when*
the stresses in the steel were excessive and the stresses in the eoacrefc a-
ceeded the ultimate strength. The locations of the cracks tihown mnt
obtained by measurement. It is probable that cracks occurred in the invert,
although no definite information was obtained on account of the flow of

sewage. While this structure did not fail nor was it distorted to - * ■•

able degree, yet the small clacks showTi in the section could be eai^i

and showed clearly that the steel had stretched st\^cl*mi\y to ailj^v Um'

concrete to crack.

ANALYSIS OF 15-1/2 FT. SEMI-ELLIPTICAL SEWER SECTIOK W,
METHOD FOR INDETERMINATE STRUCTURES

As an exaniple of the analysis of a different type of structure from thai
previously shown, the following analysis of a 15 ft. ^ in. &emi'>«tti|»tiQil
type of sewer section will be of interest. The computations are given ill
Tables 157, 158, and 159, and the arch section, the force dlfigram md
the equilibrium polygon are shown in Fig. 190. As the method at aoal^'Hft

Table 157.^ — CoMPUTATioNd dp External Forces akd MoiirxTs

AnAty^ of Ih ft. a in. 8c rain! Hip ileal Sowen by Mrthod for Ifii|pt«miin4>(e Rtr

1

2
TLickneiBi

3

4

5

6 ( 7

Co-OTdi-

8

9

10

11

Section

of nng ftt

t*.

d«.

WkUit of

mt '^ U

dm

aamber

CMsntcr of

MoyoQ, (.

ft.

fl.

ft.

ft.

<wcit«r of

X lib

m.*

X, t%.\ V, H.

i<'^J^

1

1.30

2.1U7|2.4i:ra97{l.31

0.13

0.13

0.017

0-019

'im

2

1.30

2.107 2,4lll.007|iJ 40

1 10

I 10

1.210

1.327

m

a

1.80

2.107 2.*OrO»2 5.0ft

2.85

2.85

8.123

8.8IW

S.df

4

1JW>

a.f^VK - lu n KHt^ r. ij 4.U4

* 4.84

23. 4'/'^

HI •^\ri

A Li.jk

5

I 51

3.ti .► 0 98

6.98

48 V

0

1 G8

4.74- ■ .' ■ ]7] 0.25

9.25

85

7

i,m

e.4;i5 2.d«o ;i7i H.ti3:ii 50

11.00

IM

s

2-00

8 00l»2.:i9|0 29^ 8.77 I3.0rt

13.90

r«»4 -

9

I as

7.415,1.810.244 7.89 15 52

15.52

10

1.96

7.415 1 80 0 24a ft IQin 15

Irt- 15

u

I 05

7.415,1.5.r--^ -•• r.i

10.01

12

1 94

7.3011.- ^2

10.92

13

1.94

7.301' 1. Si .^,. ..... .. U7

1 i 1 i

17,07

*""' ' ■ ''"■-■■

'a

!

7-208

1

MM 14V

-M

THE ANALYSIS OF MASONRY ARCHES

499

mofbs.

45oom.

i^Hj. 11,262 lbs.

H.-&255lb^ .,

iction

Force Diagram.

FiQ. 190. — Analysis of semi-
elliptical sewer by method of
indeterminate structureB.

^1 H.»^6255lb.

500

AMERICAN SEWERAGE PRACTICE

w X

00

J .2

Hi

2 ■^'•"~"<;

17,132
114,140
277,400
467,475
615,660
725,870
853,950
788,550
724,050
668,200
638,440
616,000

6,606,867

« A.

s ^'r <

15,558
40,051
57,310
66,970
66,560
62,565
61,165
50,772
44,840
40,234
37,762
36,092

579,879
- A-

2 lL-=^

14,182

36,676

64,392

96,506

132,060

168,647

204,553

208,080

184,516

165,574

152,884

146.132

11 1 12

Difference between
successive
co-ordinates

S4i

S

C

S§2S^^SSSS2

.-<i-<C^C^WCii-<000

0

0
C^

S S § f: § 2 88 g {2 J2

iH«-h«-hOOOOi-Hfh^m^m
1 1 1 1 1

10

Sum of

hori-

sontal

loads.

lb.

i-T CO »o inT 0 co" inT r>r iC r>r rsT r^

0

Sum of

vertical

loads

2u>,

lb.

Oioor^co»ooQOcoi^r^'^500

C^I^OOCOI^*-<COOCO'^COC«

« S S 2 ?f S S Si" S 2 2 ■»"

^ ".S'o a- •
■" III*' =2

" a § ■? 2 ^ 1 ^

" t g 2 s ^
> .S 0 0.

Q ^"3 is

i-T T-T m" c^" c^" c^" co"

—

c

ic ic c^ 00 0 00 0

10 Oa 1-H Ci 1!}^ Tti 0
»-^ »-^ C^ C^ C^ C^ CO

-

--

) (N CO ^ '«t< CO r^ '<}<
> rf 0 t^ '•t' c^ 0 0

) 00 05 05 0^ ^^ 01^ (N

I— 1 ^H f-^ I— 1

S g 2 S ?? S 2§ g § K S 2 §

C^^ '^^ ^^ ^^"^^^^"^^^ ^ "^ ®^ '^ ^

1 1 1 1 1

'

IT

5

)iOOC^C^XOCO(N
«(M^-^C0COC^00C

* »o r^ o> ^ CO CO oc r^
r o^" m" ^f CO cc co" CO cs

1

s

1

CM C^ CS

^ S5 ^

l>- t>. f^

1 1 1

"

^ ic 0 c^ c^i X 0 c?

* M ^ ^ CO CO C^ X

^5 M c^i ro ro c? CO

1

Section
number

<c^coTt<»cot^xa

5 C

CM cc

THE ANALYSIS OF MASONRY ARCHES

\y the same as that doecribed for the horseshoe section, no detaiJ6
Uon is necessary.

Table 159.

AxiaJyiu of 15 ft 6 iiu

— Bendiko Moments, Thhustb ani> Shears

Semi-ctlipticAl Stiver by Method for iDdotcrminnie Struetuw*"

1

2

3

4

5

6

Total bendinK

Thniit«»

Epcpntric

Shean,

S^tiOO

I H.V.

momcats, M,

^,

dUtnncan, «,

r.

ft. lb.

ft, lb.

lb.

ft.

lb.

t^roni

7,103

11,2432

0.632 !

0

1

1.464

8,567

11,870

0.723

3,950

2

12,388

5,a09

14,600

0.364

3,000

3

32,m7

2,524

17,260

0,147

3,630

4

54,608

- 2,681

19,800

-0.136

5,250

h

7Hfim

- 10,7IH

22,150

-0.486

6,140

0

104 J 74

-20,7Sa

24,320

-0.855

6,580

7

iaO,639

-30,905

26,100

-1,190

6,800

8

157,217

-40,233

26,900

-1.500 ,

6,350

9

174,786

-26,191

13,420

-1.950

16,350

10

1S1,RSI

4,465

10,450 1

0.430

12.750

H 1

187,062

28,591

8,350

3.430

8,650

12

100,553

44,772

6,900

6.490

4,300

13

192,242

53,213

6,255

8.500

P.L bv.

60,376

8.50

0

Conditions. — The eewer section shown in Fig. 190 is of the general type
ihciwn in Fig. 151. It is assumed that the depth of earth fill over the
crown of the sewer is 24 ft., that the weight of the earth filling is 100 lb. per
cubic foot, and the angle of repose of the earth filling 30 deg. It is further
Mwuned that the sewer is to be built in compressible soil without the use of
P»k» or a timber platform,

Bending Moments (All Negative)

^ - (6,279 X 2,19)4- (443 X 0,97) = 14,182
•*• * 14,182 + {11,708 X 1.66) + (1,748 X 1.75) - 36,676
«i ^ 36,676 -h (15,827 X 1^31) + (3,509 X 1.99) - 64,3112
"»• * 64,392 -f (19,613 X 1.03) + (5,567 X 2.14) = 96.506
«• » 96,506 + (22 J45 X 0.77) + (7,947 X 2.27) = 132,060
"«? »■ 132,060 + (25,170 X 0.46) + (10,6^12 X 2.35) = 168,647
«• * 168,647 + (26,618 X 0.14) + (13,635 X 2.36) * 204,5,53
«t » 204,553 4- (27,006 X - 0.88) + (17,617 X 1.66) - 208,080
•w • 2asaS0 + (20,377 X - 1.70) -f (17,517 X 0.63) - 184.516
•u - ia*,5l6 + (16,407 X - 1.75) -^ (17,517 X 0.46) - 165.574
«u • 165.574 -f (10,354 X - 1.75) + (17,517 X 0.31) - 152,884
«i|i • 152,884 4- (5,246 X - 1.79) + (17,517 X 0.15) - 146,132

602

AMERICAN SEWERAGE PRACTICE

Mo =

579.879 X 46.901 - 0,5Q6,§S7 X 7.26^

46.901 X 46,901 - 548.140 X 7268
H- 11/262.
579,879 X 548,149 -0.506,867J< 46.901

7.268 X 548.149 - 46,901 X -iaTOOl
+ 7,103
M, _ 7,103 _ , oft^o

COMPUTATION OF STRESSES IN ARCH SECTION

In the previous (Iiscus^iunH the thruHt, shear and bendix»g oiam£i^i ..«-
been computed for the various sections of the arch ring. The ac^ «lcp
in the design of the sewer arch is to determine the maximum *»lf«««* in tbt
masonry or steel in order to make sure that the actual BtrtsasM do mk
exccKKj the safe working streaaes and, further, to determine that the
has l>een /leslRuefl as economically as possible.

As already stated, the shear can usually be neglected in c
forced concrete arches, for concrete is relatively strong in rt^-
tlie arches usually employed in eewerage practice do not develop high
in shear.

In order to simplify the discussion, plain concrete or maaotiry
will lie considered separatdy from concrete sections reinfcireed with
The following <liscusaion and formulas have been taken by pprntisnoo
Taylor and Thompson, ** Concrete, Plain and Reinforced," 2nd EiiitiijC
Let R — resultant of all forces acting on any section,
}t — maximum unit compression in concrete,
ft = minimum compression in concrete,

A^ ^ thrwst, the component of the force normal to the aectioti,
Y = shear, the component of the force, /J, parallel to the i
6 = breadth of rectangular cross-«ection, taken as 12 in.,
( = thickness or height of rectangular cross-section,
e — eccentricity, that is, the distance from the axis to the paw*
application of the thrust, which is the intersection of th» Km
pressure with the plane of the section,
M — bending moment on the section,
/«' = maximum unit compression in the steel,
/, — maximum unit tension or minimum unit compression in ihf ft*.
p ^ ratio of steel area at both faces to total area of section.

» for rectangular sections, ratio of steel area to W,
n - E»/Er - ratio of moduU of elasticity of steel and ooDcrete,
k - ratio of depth of neutral axis to depth of section t,
kl « distance from outside compresave surface to neutral asdi
</' * depth of steel in compression,
d = depth of steel in tension,

a « distance from center of gravity of symmetrical section
f» - value of eccentricity which producos 0 stress in concrete
edge of rectangular ikcction opposite to that o^ "^'*^i
acts,
C*^ C« « GonstaolB.

THE ANALYSIS OF MASONRY ARCHES

503

Stresses in Plaiii Concrete or Masonry Arch Section. — Sewer axches
Dn^tj^cted of plain concrete or masonry should be scj designed that the
rif of rcsigtancc will not lie outside of the middle third of the seetion at
asy f>omt. It is assumed in the design that plain concrete, brick or stone
inajpi>rny cannot resist tensile stresses, and on that account the line of
roii8ti*.ticc should lie within the middle thirds so that there will im nothing
t c€>Euprcsssive stresses developed.

Pbe general formulas for the compressive 6tr688es» both maximum and
%nua, in any section of the arch ring, are as follows (see Fig. 101a):

Maximum - /« ■* ^ ( ^ '^ t)

Xf— r* ^ It ^\

Mmmvum =^ f,' ^ -^il ^ jj

b€-»iu* E;onerfil formulas apply to rertangukr sections and will bold as
[ a-ts tfn' saft^ ti'iiHiki strength of the concrete or masonry is not exceeded.
£viously»tat«d, however, no tension should be allowed to exist in the

f*H{--»t

^IQ* 191« — Stresses caused by forces acting on plain conorete section.

rmuonrr. In the examination of arches already constructed, it sometimes
jwippftns timt the line of n'sistance is found to be outside of the middle
HmM and since it is assumed that the material is unable to carry tension,
y^^' pf»!Ceding formula is not applicable f<ir computing the etresses on the
<^tioii, In this case the strops is distributed as compre-ssion over a depth
IJiuui the entire depth of tVie sectiou and cracks may be expected on the
side (see Fig. 1916). The maximum compression in this case

2N . .

■ jj. where g = dtatarice from point of application of thrust to most

i'**tiini (»ompre«aed surface,

«*fWsei in Reinforced Concrete Section* — In reinforced concrete sections

I*^ J»n!» of steel in compression can be replacexl in the design by an equal area

y» ^onerctc by multijjlying the steel area by n, the ratio of modulus of ela^

I wcily of jjicH.4 to the modulus of concrete* The moments of inertia may also

I "•iMimuanHi in n similar manner and the section treated in the design as if

<'omp4.med of concrete. In the design of a reinforced concrete

Liniwl that the concrete is not allowed to carry tension, but

'^"t all i4 tijtj tensile strfasea must be carried by the steel reinforcement.

504

AMERICAN SEWERAGE PRACTICE

\o Tension in Section. — The following equation expresMfl the Tiloe
of the maximum unit compression in the concrete under conditions wbeie
no tensile stresses exist in the section (see Fig. 192).

6ie 1

P + i2npa> J

Tliis con^lition does not necessarily mean that the line of preflsure liei
at or within the limits of the middle third of the section, for in a reinforeed
concrete section the value of the eccentricity, e#, at which there is neither
compression nor tension at the surface opposite to that on which the thnist
acts is usually somewhat greater than //6. For greater values of the eccentri-
city than Co. and assuming that the concrete is unable to carr>' any tensoo,
the above formula is not applicable.

For convenience, the above formula may be expressed as follows:

\Cc

base<l on the assumptions that n = 15 and 2a = U^ which are reasonable
and can l)e used for most all cases without great error.

In the (liajo-am, Fig. 193, are given values of C« for various values rf

e/t and different percentages of

**''^'« ^' = [rrwp + 7 T+§8:8 J

■Vii-1-i

Tjsr

Fi(i. 192.- Stresses caust'd by a force
producing coinprossion uj)()n the whole
reinforced section.

steel. The curve in the lower
right comer is plotted to gi\*e
values of e^/i or different per
centages of steel, and is useful fiir
determining whether or not a given
eccentricity will produce tension in
the section. For example, if the
thickness of the arch section is IS
in. and the percentage of steel rein-
forcement is 0.8 (p= 0.008) fr«)m
the curve Co/t = 0.183, and therr
fore Co = 3.29 in. This means that
the line of pressure or point of application of the thrust cannot 1)0 more
tlum 3.29 in. from the arch axis without producing tension on one side.

To illustrate the use of the curves for T, if in the above example the
eccentricity is 2 in. v.'t = 2. 18 =0.111, and Cc = 1.44. Therefore/, =
1.14.V -7- (12 X IS), from which the value of /c can be found if the
thrust .V is know.

If tension (hK\^ not exist in the scM'tion, the principal stress to l>c deter-
mined is the niaxinuini compression in the concrete which must not exceed
a safe workint; stress.

Trusion in Sect inn. — When the eccentricity is greater than <« and tbt*
concrete is considered as unable to carry tension, the following fonnula
should bi; used Csec Fig. 194;:

M

/c =

Cahr-

when'

^m THE ANALYSIS OF MASONRY ARCHES 505 ^|

HBHitate the oomputationa, Fig. 195 is given. Deteniilne e/t and from ^^H

ni^t-hand diagram find the corresponding value of k for the given ^^H

^iag!e of steel. Then with tliis vaiuo uf k use the right-hand curves ^^H

E»d the corresponding value of r« for the given percentage of eteel. ^^^

Values of ^ ^^H

•

1

/

1 f

-.^-^

^ ^H

/

//

! li

^f

^H

ff*-

g"i

^H

1

^

?

■

1

/

7

Z'

i_ ji:^

r*

w..

^^^

i

ll

/

{/,

^

"^'■t|*r,p*

feU

^^^^^^B

t*+llnpa

^^1

w

ii

/ V

//

V

fi

//

qA

¥\/

^«- .'.5p*? .

tJ

^^^^^^H

^^g

1

//

/j

fjf\

\

I

/

H

ty. ^^H
(rentage ^^1

I

y

1

1

7/

ft

/ i

** '^ l + np J

ir.

y

K

>

' 1

//

/A

1

/

1

'//

VA

7

e. l + S.ftV

/

'/a

W

/

/^

1

'//

Y

J

/

III

//.

/

////

f\

/

f -

-

u

J

/

r/////

f

/

1

f

—

J

r

/

m

7

.0 .2 ,4 .6 .6 LO r.2 U 1.6 I.
fercentQ9e R«jnfo^cef^€^■^.
ho, 193. — Diagram for detorinining compriMMon and eccentrici

fk- 1^ ftmi 2a -it

Kiuc#<J by pttnniMioii of the mU*tir» ham "Conctatc, Pfnia »n<i H<ria£oreod,

tnlitioa, by Tuylor »acl Tbomp(»ou)«

r lUuatrfttion, if In the example previously given the value of
1 = 0.56 and from Fig, 195, k = 0.46, and the steel per
uBlH^foiv. r. = 0.1215. Then/. = .V ^ (0.1215 X 12 :

tmi which the value of /. can be found if the bending niomc

fc.' xStitmiSi m 1^1 ,to .c^uloV

\ '

Ti

^

L

4

E

■

z

"

^^^H

,

■

:

^

^

1

1 r

i«

'

■

•

^a Iwf i<y^tt»iotit»y f^mtMAmkmamm '^

606 AMERICAN SEWERAGE PRACTICE

known. It should be borne in mind that if e and ( are expreaaed in i
the values of M should be in inch-pounds.

Having thus found the unit stress in the concrete, the unit streans in the
steel may be found by the following formulas (see Fig. 194);

/.' = n/e ( 1 — jTT ) =* maximum unit compressive stress in steel.

/• = nfe I — jTT — j * maximum unit tensile stress in steel.

Shearing Stress, — This is found as follows:

Let V = total shear at any section,

V « maximum unit shearing stress,
6 — thickness of section assumed » 12 in.,
jd = arm of resisting couple = approx. id,

V SV

then t; - ^ - (approx.) =75^.

As a rule the shearing stress may be neglected, but in the case of on
two critical joints subjected to a large bending moment it should be <
puted. The above formula may be used.

ill i !

1 i-t i^n^i^^i.

'~ t'NeiithJATiA

■'1L-» •s-sr-.

FiQ. 194. — Stresses caused by a force producing compression and tenaWj
upon a reinforced section, tensile strength of concrete neglected. \

Bond Stress. — This is computed as follows: |

Let u = unit bond stre^ss between concrete and steel bars,
o — perimeter of one bar,
So = sum of perimeters of bars in unit length,

then « = j.J^y = (approx.) = ^ ^^^^

The above formula can be used when necessary to compute the b*(
stress, but as a rule this computation can be omitted. |

\

TRANSVERSE STEEL REINFORCEMENT

f

The fact has alretuiy been i)()inte(l out that the introduction of rt*»
reinforcing bars to strengthen the arch where only compreaA*
stresses exist docs not porniit of any great diminution of 1M
concrete section or any marked economy, but it does have 4*

\

\

V

^^^^^^^^H^BmtPp^^^l^^^^^^^^^^^^^H

■

m

■

V

1

11

1

1 ■

■

J

^

[TB

^H

'^

1

I

I ^1

^^B

n\r m^ *o _«uIdV

liMPfl 1.1 ■

^^K pMi^^v

J

^^■■H

THE ANALYSIS OF MASONRY ARCHES

507

;e uf making the struc*
liable and acts as a sort
against unforeseen
liable to occur, auch
e to temperature changes
of the concrete, settlement
tiions, and the like. It al^o
clitional factor of safety
workmanship in tho con-
le «ewer section. While
may make an effort to
^nditiona and to provide
forccment or thickness of
witlistand the stresses as
e is an uncertainty con-
tiou of arches for which
le wholly to provide,
these considerations, it
transverse steel reinf orce-
in concrete sewers, even
computations may show
ine of resistance lies every-
hin the middle third of tlio
lotion. It is impossible in
hement to make use of the
fWI allowable compressive
^fPu^d in steel design,
compressive tttress which
bed in a reinforced eon-
Bigned in accordance with
methcK:! of computation,
I great<ir than the al low-
stress in the concrete
the ratio of the moduli
n* This, under ordinary
klaces a Utnit in compres-
Btei^l reinforcement of ap-
7500 lb, (600 X 15) per
If a greater compressive
bo developed in the steel
lion would be sufficiently
fitrcft8 h!h1 rri<:^!i Mm- con-

tice inc amount of

41

.2 S

||gS8

?0 05^ !N O ^^
CO CO" PO" iti i6

3 S 5

-^r o Qo t* 'f

J S*? C* Q 00 W

c9 «o S oi cp

I C^ ^30 O ^* 'O

ga O O c«' -^
' c^ *o t^ '^ ^

l>- ^1 »0 00 00

00 00 »^ tf> w

O O •^ "^ •-«

di ^ (6 ^ Gz

r- !D h- M ic

CO cS c*5 ^ rC

o o o o ©

I o o o o o

li

^ S .^ o o

II

iU

O O W -^ "^

gj ^ « « <o

c ^ ^ ^ ^ ^

II

w o o o o

h^ « 00 d O

00 ^ 00' 00 X<

S Q S 00

■^ 55 r* o «

508

AMERICAN SEWERAGE PRACTiCB

transverse reinforcement in arches usually varies from about 0i2t
h5 per cent, of the area of the concrete masourj^ at the ccrowti.

In designing the reinforcement for a sewer areh, it is nocc«Nify ;o
asaume a certain percentage of steel at the start, as will be noticed fma
the method of computing fiber at reuses, already given,
putations have been made the actual percentage to be »i
justed in accordance with the rasults of the oouiputation, in ovia M
obtain the mo«t economical arrangement passible.

Computation of Transverse Reinforcement for 15 ft 6 in. Semi-
elliptical Section. — As an example of the method of computing ifai i^

"Jaq.Bap,

C ros& S ecl-i on .

Longitudinal Sec^>9«

Fig. 196, — Steel reinforcement of 15 1/2-ft, aenii-elliptical

inforcement the following computations, Table 160. made for tlie 15
ft. semi-elliptical section previously analyzed, are given^ As % nik
not nccessarj' to compute the stresses for each division, but merely
few critical points*

It Ls oujstomary to keep the same nize of bars^ and the sani
upper paii: of the arch, changing either or both if necesfcii- . „, ,„,
wallfi or in the invert. It is desirable to have ua few di^ei^at
bars as practicable. In general, smaller bars t
able to larger bars with wiile spacing. A.tyi
transverse steel reinforcing bars is shown for the id ft. li in*
elliptical sewer in Fig. 190.

THE ANALYSIS OF MASONRY ARCHES

509

|t will he noted that the shearing stress on division 9 i» Yugher than

aonly allowed. While there ia some question concerning the ne-

^ of keeping the shearing stress at this particular location within the

lowable liraite, tliia can be done by incrciLsing the concrete in the

* as ahown in Fig. 196 by the dotted line on the left aide*

LONGITUDINAL STEEL REINFORCEMENT

onry structures of all kinds expand and contract with temperature
This is especially noticeable in concrete structures, for the
cks are more readily seen than in stone or brick masonry structures
pre the crackii are difftributed among so many joints as to be prac-
Xly invisible. Concrete conduits or sewers are subject to tempera-
changes, particulary during the period of construction. The ex-
sion of the masonry rarely causes trouble except at sharp angles,
contraction is more likely to cause difficulties.
Two mcthoda are in use for preventing objectiona!:)le cracks caused by
shrinkage of concrete in hardening and the contraction due to a
rering nf the temperature. One method is to locate expansion joints
|uent interv^als^ approximately 30 ft,, so that all of the changes will
eoncentrated in one crack at each expansion joint. The second
thod is to insert enough reinforcement composed of small bars placed
t.he surface of the concrete to dii?tribute the cracks at short internals
1 make them so small as to be practically invisible or unobjectionable.
I actual practice it has been customary to insert from 0.2 to 0.4 per
pt, of the area of the concrete as longitudinal steel to resist shrinkage
temperature stresses. For this purpose deformed bars furnishing a
[ti mechanical bond with a high ehisitic limit are advantageous.
It is interesting to note that concrete laid during warm weather is
||ch more likely to crack on account of temperature changes than
Jncrelp laid during cold weather, and in addition, shrinkage cracks are
more apt to occur with concrete laid during hot, dry weather unless care
ken to keep the concrete wet,

actual amount of steel reinforcement to be provided to resist
uper&ture stresses is, to a certain extent, a matter of judgment. For
iwer constructed in comparatively dry soil and designed to carry both
face water and sewage, the presence of smid! cracks might be con-
sidered unobjectionable. Large cracks would doubtless be objectionalile
i account of the possible rusting of the steel reinforcement and conse-
nt weakening of the structure. For a sewer constructed in very wet
adjacent to a river or a creek, where it is essential to keep out as
kcli ground As*ater as possible, the presence of even small cracks
bt be objectionable.
r^vlor and Thompson, in ** Concrete, Plain and Reinforced,*' second

510

AMSmCAS^ SBWERAQM PRACTWB

edition, page 501, give the following fommla, siiggeBled Ivf
M. Millfi, for estimating the size and distance a^art of encka, i
form a basia for judgment aa to the sises and penseotagiei of

use. Let x = distance apart of cracks, D = dtamcier of
or side of square bar, p = ratio of crosshaectton of sled to
tioD of concrete. Aasuming that the strenglh of DonereCe b t
equal to the bond between plain steel bars and ooitcrete the
apart of cracks is j- = D/2p for square or round bars. If
plain bars deformed bars are used, having twice the bond
plain bars, the cracks would be one-half as far apart and only
wide.

Taylor and Thompson also suggest that the siie of the
Hoover ned by the amount of shrinkage and on that account the
be estimated a^ the product of the coefficient of contractioQ (<JL<
by the number of degrees fall in temperature, by ibo distaDce
cracks.

If it is desired to prevent the appearance of cracks 80 far aa
and to make the sewer practically watertight 0.4 per cent, of ated
be used, that is, the ratio of the area of the steel to the arf*a rtf (Qir|
Crete should be 0.004.

The presence of longitudinal reinforcement also has t*
making it possible to tie both the transverse and I
together and thereby aid in the erection of the steel.
sets of bars are wired together at frequent interv^als ti _ _
likdihood of their becoming displaced during the placing of live car
In fact, if no longitudinal reinforcement is used on ri
perature and shrinkage stresses, it will be advisable ;
number of longitudinal bars to support and space the
While this is not absolutely necessary, it can be done at .,
and is juBtiHed by the greater certainty of having the bar* locatel
their proper places.

The following computations will serve to iUostrate the applicatiii
of the foregoing discu^^sion:

Assuming that the amount of longitudinal steel reinforeGm«iit to U
provided for the 15 1 /2 ft. semi-elliptical section previoualy aaaljvl
is 0.25 per cent, or p= 0.0025, and that |-in. plain square hart v*
to be used, the distance apart of the cracks would be x « Dj^ ■
0J5/2 X 0.0025 = 150 in. Further assuming that the maximum chanp
in temperature of the concrete masoiuy may be 50**, the width of ^
crack wiU he 0.0000055 X 50 X 150 = 0.0412 in.

If, on the other hand, deformed steel bars were to b©
bond strength 50 per cent, greater than that of plain baniy wl
reasonable assumption, the spacing of the cracks will be inveffibiy
portional to the unit bond of tho stod bars. In Ihia case ibo

THE ANALYSIS OF MASONRY' ARCHES

511

I the cracks wotild be 100 in. and the width of a crack would be

iti.

The area of the concrete section for the 15 1/2 ft. 8cmi-ellipiical »ewcr

|13,57ft.9 aq. in.; 13,576.9 X 0.0025 -= 33.94 «q. in, of ateel bars for

^gitudinal reinforcement. Area of 3/4 in. square l)ar = 0.5625 sq*

33.94/0.5025= 60 bars. These bars are distributed as shown in

, 19C5 so as to reinforce the interior and exterior surfaces approxi-

^tely uniformly,

SAFE WORKING STRESSES

The working stre^sea recommended by the Joint Committee on Con-
and Reinforced Concrete (Proc, Am. Sac, Tent, 3/., voL xiii,
J70). furnif^h the be^st guide for determining safe values to use in de-
For a complete understanding; of the following figures, reference
jultl be made to that report. The following working fitresaes for
icTote are based on the assumption that concrete composed of 1 part
' Portland cement and 6 parts of aggregate is capable of developing
I average compressive strength of 20<X) lb, per square inch at 28 days
Bn teMed in cylinders 8 in. in diameter and 16 in, long under labora-
conditions of manufacture and storage, using the same coimisteDcy
f lA employed in the field.

Lb. per
Bq« in.

Compression on extreme fiber not over ^0'

Sheiu- And diagonal tension not over 40

Bond, . . , ,,._.. , 80

Tenafle stress in steel not over 16,000

The above figures for concrete should be reduced if the concrete
i an average strength less than that tapccified.

UNSYMMETRICAL LOADING

direct determination of the stresses in a masonrj* arch, loaded
B>Tiunetrically by the voussoir method described in Baker's
lasonr>*" is impossible, but a solution can be arrived at by approxi-
Ite methodi*.

The elastic theory of the arch permits a direct determination of
stresses for unsymmetrical load-s, but the labor is greatly increased
Br that indicated in the preceding analyses.

* It u imi>oil«i>t to Doti<^ thftt then ficurea ato for a 1: 6 mixture luul must be modi-
l for other iTuxtuxieci jwi i*xpUific<l in the Joint ComnuCtMi'a report.. The authon' prfto-
I ii to tiAe 500 Ih. per ftqunre inch maximum eompreteflion in the extremr fiber, 40 lb.
I jihe&r where only horiiontAl mnforoement u uBed, 50 lb. maximum sbeiir with
ootftl bent^ttp bnw, SO lb. maximum «hi»r with horiioai&l bent-tip b»TO fully supple-
^1c«l with iitin-upii, AGO lb. maximum benrins utrenKlh, 64 lb. bond wUtm for plaia bars.
^ iaciuding di»wii wire, and 130 tb. bond atreae for d«f(>rmed bikia.

512

AMERICAN SEWERAGE PRACTICE

Except in unusual cases* nnd for very wide span sewer archa it i
neldora neceasary to compute the stresaes due to an unsymmeWil
loiid. If the conditiona of urusymmetrical loading are eiifiicicntly 9cv^
to warrant a special analysis, the elastic theorj^ may be used.

DETAILS

Curves,— Changes in direction of large sewers should always be J
by curves. It is impossible to give an exact statement for the proptf
radius of a curve for any particular sixe of sewer, but various apf -
mate methods have been used and found to produce fairly good r*-
The best discussion is by W. E. J^'uUer in Jour, N, K, Wol&T-Waf^
Association^ December, 1913.

W, W. Horner, in Engineering and Coniracting, Sept* 13, 1911, st^^
that in the St. Louis Sower Department the practice has been to mi
the radius of the curve as large as possible, varying from 30 to SO ^
when in street intersections and from this up to a 2 deg. curve wb<j
the angle is smalL

On the LouLsville, Ky,, sewers constructed about l^OJ^ to 1912,
radii on curves have varied from 10 to over 400 ft. for sewera from 5 tc»
ft. in diameter. The major part of the curves, however, were construct
with radii from 30 to 50 ft* in length.

Some compnisation should be made for the loss in head due to
creitsed friction on curves* A method of making such conjponsation I
already been outlined in Chapter L The formula given is that olle
by P. J. Markmann of the St. Louis Sewer Departmejit.

In Trans, Am, Soc. C J?-, December, 1905, Walter C. Parndoy sta
that in the design of the Walworth sewer in Cleveland, Ohio, all cl
in direction of the main sewer were made with oa easy curves as poasib
At one intersection where the deflection was about 90 deg. two lots wc
purchased and the sewer was built on a curve of 164 ft. radius.

Several authors suggest that the additional loss due to sharp cu
be assumed as 0.5v^/2g where v is the mean velocity and ff b
acceleration of graxity. Other designers arbitrarily^ allow a
amount of fall between the beginning and end of the curve^ the amou
such increase being selected by judgment for the particular ciwtc.

Changes in Size, — It is a well-established fact that abrupt rhjui^'^if*
the size of a waterway, such a^* sudden enlargement or sudden i
cause increased friction and consequent loss in head. If the
enlarged gradually^ this loss can be practically eliminated. Tl»<» prop
length in which changt^ in size should be made has usually been!
by judgment,

HughcH and Safford, ** HvilrauHcH/* suggest Ihat n hatt«?r of
sides of the eewer win Iw rmmil f ivfjnililr> TKi- iin-tri* i
amettsr of the sewer

CHAPTER XIV

STREET INLETS, CATCH-BASmS AITO MANHOLES

he special structurps which are built on sewerage systems have an
lortant part to play m the operation of stich works, ai^ a rule. In
r to I'lean sewora, iimnholes giving access to thrm are provided^ and
p* manholes and we II holes have been developed from ordinary man-
's, in order that sewage may be delivered vertically from one eleva-
[1 down to another with a minimum amount of disturbance. For
latter purpose flight sewera, with their inverts like a straight stair-
, have also been conytructed. WTiere storm-water is removed under-
und, street inlets are provided to discharge it directly into the sewers
drainii, and catch-basini? are employecl where this surface run-off
itaifis so much refuse of different kinds that the engineer prefers to
it a chance to settle in a readilj^-clcaned sump rather than to allow
rthing to flow without check into the sewers. In orrler that long
of small sew^ers may be kept under observation with the greatest
ility, some engineers provide them witli himpholea, down which a
p can be lowered to illuminate the interior of the newer enough to
kble an observer at the manhole on either side of the lamphole to see
,h more or less distinctness the condition of the pipe.
here are many small sewers with grades so flat that the only way to
p them clean is to flunh them with water, acnompanied if necessary by
acrubbing with a brnsh on the end of a long rod or wire. For this
iom a flushing manhole operated manually or an automatic flush-
ia employed, and there is a great difference of opinion among engi-
regarding the respective merits of the tw^o tj^pes. Occasionally a
ihing inlet is pro\'iricd on the bank of some river or pond, through
ch water can be admitted to large Hewern which need cleaning.
rhere large ^wers join together there are bclhnouths and other
*m» of junctions to be built, which sometimes a^ume forms of con-
^Klerablc complexity'. Inverted siphons are used in oroasing valleys
or dropping below subways and other obstructions. On rare occasions
A tartus siphon may be used to overcome a small ridge, although it ifl
tl^tially considered preferable to go to considerable expense to avoid
ftuch a detail. Since reinforced concrete came into use, si>ccially de*
fiign»Hi hollow grrdRrs or beams have been employed in some places
to cTom rivers or deep gulches, w^here inverted siphons or steel bridges
^buld have be^n used before. If the combined sewerage system in-

514

AMERICAN SEWEHAGE PRACTICE

eludes iutorcscpting and relief sewers, some form of regulating d»
must be used at each place where the sewage is diat^harged froa
collecting pewer into an intercepting or relief sewer; there are nvinwu
forms of automatic regidators, storm overflow chambers and Icaji
weirs umd for such situations.

Where the sewage is discharged into a river^ lake or tide watcTi J
outlet of some kind is needed; it has already been pointed out in 1
Introduction, that the failure of the designers of early sewerage aya
to allow for the effect of tidc-lo(±ing of such outfalls caused a
I>art of the really aerioua troubles with some of the sew^erage sy^U
built prior to about 1875, Even today tho effect of submergence {
the flow in an outfall i^^ew^er and on the discharge from its outlet is \
always given the attention it requires. Another allied type of aj>f
structure is the tide gate, which is a large cheek-valve to prevent \
entrance of water into a sewer when its surface elevation reaches suc|
height that tho wate-r tends to paas in tlirough the valve rather thiuii
sewage pass out.

In the early days of sew^erage w^orks, their ventilation received a 1
amount of attention and a great variety of theories exbted concern
the best way to carry this out. The omission of the main house ^
was advocatetl by some engineers as a material aid in sewer
because of the upward draft through the soil pipes of the buil iij

it was claimed would come into existence in this way. Another i
engineers vigoro.usly opposed the omission of the main trai> and insil^
upon a vent pipe run from the house drain, outside the trap, up thei
of the building to an outlet above the highest w^indows. 8tiU
engineers made u,se of ventilating chimneys shaped like the
street lamps, and sometimes used as such, and at one time |>erfo
manhole covers were in quite general use as a means of vcntilati
Taking it all in all, it is perhaps safe to say that there Ims been no i
of sewerage engineering in which a greater variety of s]KH"ial d©
has been prepared for the same purpo?*e than in ventilation, while j
vigor of the debates over it down to the last decade of the butt ccQl
was a noteworthy feature in the engineering htcrature of the day.

Although some of thc^e speciid structures ofleT no opportunity |
standardization, for the local conditions of each ca^e are
each class tliere are certain features which experience has iti
important* In rarr. cases, experience has shown further thai
details will not be satisfactoiy in service. Little ! '
toward a really thorough co-operative study f>f Tf
by engineers in different cities, but a lit
correspondence and visits between ft-n
details. In the following notes, th
structures which will illustrate ii'

STREET INLETS, CATCH-BASINS AND MANHOLES 515

I nuiubor of engineering offices. Experience rather than theory must

anfnil the design of many such details, and ii the experience of an

Bgineering ofhce with its standard for any detail has been satisfactory,

change should be made from that detail without careful considera-

on. Wliilc standardization will gradually take place» the rate of

ogreas will inevitably be very slow, a^a is always the case in advances

BojMniding upon individual experience, unaided l>y the publicity which

pro!iK»t*m jMid aalesmen give to the things they are introducing.

STREET INLETS AND CATCH-BASINS

The storm water w^hich remains on the surface of the ground, instead
percolating into it, and must be removed through the sewerage or
drainage systems, is collected in the street gutters which convey it to
rilels. The^e inlets are either the ends of direct connections to the sewers,
Of eUc discharge the storm water into catch-btisitis provided to intercept
[Ihr refuse which the water has carried from the street surfaces in its
oufse to the inlet. It is evident, therefore, that the location of these
ilct* is a matter of importance to tlie authorities in charge of the streets
i Well as those who are connected with the sew^er department, for it is
Joaiiifcstly important to kc*ep the streets free from water and the gutters
la «uch condition, even during a heav^ rainstorm, that it is possible
Uor learns to drive close to the curb and for pedestrians to cross the
et with the minimum inconvenience. A little consideration will
libow that there can be no ftxed rules governing the location of the
IW**t«, if the convenience of the public is to be served moat effectively.
ITlie topography of a city often tends to concentrate the run-off of storms
ffo c^rrtain places, and it h the duty of the sewerage engineer to prevent
■this! cone I vnt rati on so far as practicable. This can only be done by
lititcTfcpiing the storm water as it flows through the gutters at the
[higlter elt*vation8, and to accomplish this in the best way the street
department may be very properly requested to depart at times from
Slime of its standard regulations regarding curbing and gutters. The
•trw*t department may have good reasons for refusing to allow any
^ddeu drop in the grade of a gutter at an inlet, for such quick deprea-
uioiiit, even of a depth of 0.5 in., invite an early disintegration of the
niAtaial of the gutter at that place. This is not true, however, if the
Tr rather gradually, and there is no valid reason for
a depression in the gutter in order to give a depth of
t auie-hiU street which will permit the construction of an inlet
•"^rn for the storm water that should be inter-
are made at the outlet of the discussion of
»erutii*e the lack of co-opej*ation between
n I ! I < T K - 1 1 aa been ihg cauae of BCime unaatiaf actc

S16

AMERICAN SEWERAGE PRACTtCE

design in the past* A good comment on the sitaation bm itexiilil
many cities — recently received from W- W- Horner, of the St* Lftdl'

sewer department — reads as follows;

'^I think the use of standard inlets at standard locationti witboiit i
to the work required of thpjm, is the most common fsinlt in mswer da
The street pavement officials usually demand that there shjill be i
in the curb line at an inlet and no grt^t flepression in like pav
gutter. Under these conditiona inlet.s on steep «trrc f
at the foot of the grade, are almost usiele^s. Our
the curb is 4 ft. long and 8 In. high, and only a sm/iU p fif ^

height, 2 to 4 in., is below the normal gutter line*. TheoiU
to lie in the multiplication of these openLiiga, two to four in a amm^ audi
continuous basin behind the curb and under the sidewalk,*'

Unfortunately the sewerage engineer rarely has anything to aar <
cerning the grades and cross-sections of the gutters in the streotji.
public suffers from this, because at thc^e places whore it is most hop
tant to keep the streets free from water, that is to say, in the <
where there is heavy travel on the pavement, the proper I
ia mo«t important and the Htreet department generally so:
ing the uae of as few iidets m possible, since they arc an undou
terference with the most satisfactory execution of curb and gut
struction. Wherever a street inlet exists in such a crowded thoro
it is a more than even chance that there will be soni' >H

ment, due to the passage of wheels over the inlet r; dl

sills which are sometimes ascd instead of castings. Nevertheless, \i\
the convenience of the public which must be considered in sijtrli
and that convenience demands that there shall be an ample number I
these inlets located where they are most needed.

This location is ver>^ difficult to obtain if determined by anything ftt*
cept the exercise of good judgment- Experience shows that in a \
city gutters of a given cros»-section and slope will care for the I
of districts of certain sizes, and that larger districts will cause the|
to be over-filled. This information, which can only be obt>aine
observation during a number of years, is not always available* No d
can fiu-nish such information to the doalgning engineer, l^nd he J
proceed on the assumption that inlets should never be iii
300 to 350 ft, apart where gutters should carrj^ only a i
water, and never more than about 700ft* apart, and that where twogn
join to form a valley, an inlet must always be placed in the valley j
aide of the street. The gutters should be so constructed, the i
tion of the stref^t should be so aelectod, and the iti " ' ' il

water will never flow across the pavement in or^i
rare cases a gutter may be connected ^nth another on the oppcit
of the street by a culvert, but «uoh a culvert should be oaref ally i

STHEET fNLETS, CATCH-BASINS AND MANHOLES 511

jithat it can be kept cloau and free from water which will afford a breed-

pUu»e for mo^!quitoGs. On straight li^'ades the itileta fire placed at

street comcTfi. Although it is customary in many places to locate

inlets* lit the ang;le uf the corner, this is a poor place for them if the

%\g\ on the street is more than moderate, for the wheels of trucks round-

the corner clo»c to the curb are i>articiilarly hard on both pavement

inlet casting in such a position. If the grades are steep an inlet

each aide of the corner, just before the crotss walk ia reached, offers

! best solution of the problem in most cases. In case oi doubt it is well

to remember tliat the convenience of the public is better aerved by

having too many rather than too few inlets. What has been said applies

etioally well to street inlets and to catch-basins, although there is oon-

■JeraVjlc difference between these two classes of structures.

B Street Inlets, — Since a street inlet affords a direct connection between

the gutter and the sewer, it ia very important that it should be so

designed that as little opportunity as possible exists for its stoppage.

The obstruction may arise through the clogging of the opening (mouth

Kr gully) by which the water enters, or it may occur in the trap if it

^Bs one, like A in Fig, 197, or it may occur in the pipe running to the

^Mrerp The objects which cause the moet trouble at the openings of

Hie inlet are sticks, waste paper, and leaves. If sticks become lodged

Hs^^^^ ^^^ openiug the leaves and wa«te paper drawn to it by the next

flush of storm water arc likely to cause a stoppage. To avoid this some

gineers have tried the use of openings prejjenting hardly any obstacle to

entrance of these three classes of refuse, but it seems questionable

bether it ia safe to allow sticks, at least, to enter the street inlet, owing

the danger of stoppage of the pipe leading from the opening to the

ver,

I As a general proposition, it is probable that street inlets are better

iapted for busy streets with good pavements which are kept clean,

"particularly where there are no steep grades nor any topographical

conditions tending to concentrate the storm run-off at a few points,

than they are for streets furnishing large quantities of refuse rarely

removed by street cleaning, and liable to have the run-off concentrated

at a number of places to which many storms are certain to take a large

amotint of street litter of every sort.

klf the sewers in a district are on self-clennsing grades except at a few
inta, it may be best to construct grit-chambers in the sewers near these
aces in order to keep down the expense of maintenance by forcing most
the grit to gather in piU whence its removal will be less expensive
than from the sewers of low grade.

In 1913 a number of standard types of street inlets were adopted by

president of the Borough of the Bronx, New York City, These

i shown in section in Fig. 197. Type A has an opening 7 in. high and

518

AMERICAN SEWERAGE PRACTICE

2 ft. 8 ia. long, in the curb. The box of the inlet is 3 ft. 5 iiL X 3 ft-
6 in, X 5 ft. 0 in, doep, iiiBide climensions. The 12 in. vitrified pip«
leading from it has a vitrified cover through wliit-h the pipe can be
cleaned if it should bfx^ome stopped. The quarter bend ia so plwedi it
will be observed, that the inlet ia actually turned into a diniioutive
catch-basin* In type B the inlet has a box 3 ft. 5 in. X 2 ft. 8 in. X ^ ^^'
6 in. deep. The opening in the curb is 7 in. high and 2 ft. 8 iiL long*
ThiB type has a 12-in. sump below the vitrified outlet, but la^kfl the
water seal of type A, Type C hiis a box cirrular in plan 2 ft. fi in* ^^
diameter and 18 in, deep. In order to give it sufficient receiving capacity

I /^5 i

Fin. 197. — Standard street inlets, Bomugh of the Bronx.

the cast-iron head wdth which it is provided haa a gutter grating »B W" ^
as a curb iniet. This type has no sump and cvcrytliing which enlcr^
goes into the 12-in. connection leading from it. Type D haa a l>**^ |
36 X 18 X 20 in, deep, with a curb opening 5 in. high and M in. lo^'^^'
The type E la ^ gutter inlet having a grating whi(»h alone furnii^hi* ^'*
inlet to the connection. The box of this inlet ia 14 in. wide aii
depth varies as shown in the illuHlration,

A type of inlet which the authors have found vm* snt t?eftt<et<ji
work is iUufltrated in Fig. 198, It ha^i tl.
imparted by the8iil>slan*i"^ '•' "^^ <'^ \a..a

STREET INLETS, CATCH-BASINS AND MANHOLES 519

led, relatively low cost, a large grate opening, and emy construction.

Buthors' experience with inlets having risers of straight pipe is that

;rattng3 do not Lave adequate openings, and the use of a reducer is
desirable in order to gain room for a larger grating,
Philadelphia a standard inlet has beeji adopted which ia con-

jt^ wholly of concrete, brick and flagging, as shown in Fig. 199,

iZ'*Wr\Ptpe

Section A-B,
Fro, 198.— Standard inlet, Metcalf and Eddy.

I shows Iwo variations of the type, one with a curb and the other
^ a gaffrr opening, .

-ba&ina*— The catch-basin was formerly considered an ab-

part of any American combined sewerage or drainage

V lice had shown that the velocity of the sewage flowing

/ar» wa0 in»ufiicient to prevent the formation of beds of

* ncwtrre, and it wa« manifestly more expensive to re-

520

AMERICAN SEWERAGE PRACTICE

move this sludge from the sewers than from catchrbasins. Tbis ex-
perience was f^ained in days when the pavements of American streeta
were crude and little attention was paid to keeping them clean. Th»
sewers themselves were not laid with that regard for self-cleansing veloci-
ties which is paid now. Under such conditions it was but natural tliat
catch-basins should find more favor than they do at the present tirxxe.
Durable pavements, more or les? efficient street cleaning and sewers
laid on self-cleansing grades, have reduced the need for such special

Cvrb .^

k- 4'9i'- ^

Section E-F.

Fi(i. 199. — Standard inlets, Philadelphia.

Half Top Plan.
(Casting Removed)

atructuros to a few situations. The following quotations show the
of opinion at the ])rcsent time.

*' Wo are also of the opinion that the inlets should not be provided i^"*^^
catch h.nsins to retain the filth or whatever may be washed into th^^*^'
The object of such basins is to intercept heavy matter and periodically ^^^
it away, instead of allowing it to reach the drains and there to dcpc^^*
Catch-lmsins, even after the sewage flow no longer exists in the gutt-^^*
are still apt to get foul because of the organic matter washed from thertf^^**
8uch foulness is less oflensivc in the drains then in the catch-buuii vl*^

i

STREET INLETS, CATCH-BASmS AND MANHOLES 521

attmted at the side walk aiid where ii is much more Ukoly to he oIj-

aerv^Mii Also, it is found impracticable to intercjept all matter in the catoh-

tins which would deposit in the drains after they reached the flat grade

[the lower part of your city. The clpaning of the drains would, therefore,

t neoeasaxy in any event, and the additional amount of filth that would

berwiae be intercepted by the catch-basms, will not cost much more

Iremove/' (Ileport by Rudolph Hering and Samuel M. Gray on Sewerage

Drainage of Baltimore, 1896.)
I **Thcnrel;caUy desirable, catch-baains are, in reality, among the moat
Bless devnces employed for the removal of solid material fnjm sewage.
ey are generally ineffective because they are not cleaned with aufficicnt
[juency to enable them to serve as traps. It seems impracticable to
keep them clean » To maintain catch-basins in serviceable condition
fequiros much hand labor^ and this is costly. The work is usually carried
on to the annoyance of pedestrians and hou'^jeholders. Some ^werage
systeins are without catch-basins and their eUmination, as a general
procedure, is much to be desired." (Report, Metropolitan Sewerage
Commiaaion, New York, 1914.)

**Thftt the sewers built bj* the Commission might become at once effect*
Ive in provifling for the disposal of storm watex and thus fully useful at as
|uly a date as possible, the Commission has built 225 storm -water inlets,
^^wliich some have been in the form of catch-bastns. Careful considera-
^■ii WHS given to the desirability of building inlets rather than catch-basins,
H liAd been the city's custom for many years. It was felt, however, that
m this climate it was unwise to provide pools of water in which mosquitoes
could breed, as in the case where catch-basins are built, and further that
under existing conditions the catch-baalns, for the detention of detritus,
were not necessary in most cases. It was also found that it was already the
practice of the Board of Public Works to build inlets instead of catch-basins,

fe inlets as built have been untrapped and the experience thu.^ far indicates
it thia type of inlet has given satisfartion/' (Report to Commiasionera
Sewerage of Louisville, by J, B. F, Breed and Harrison P, Eddy, 1913.)
**In rural districts the gully retainers are often allowed to stand full of
grit for months together, and an}-^ such detritus brought down by the
rain thus runs straight into the sewers. If the rc»tainers are not going to
be emptied after each hea\^' fall of rain they might as well be omitted, as
they are serving no good purpose, and may even cause considerable odor
when they are allowed to stand full for long periods. In other places the
guUies may onh' have to take water flowing on large paved areas where
no mineral matter of any importance can reach them. In such positions
the retainer merely sen'es to retain soft matter which would be better in
the sewers, ^^li^n we remember that a velocity of flow equal to 3.3 ft.
per second will carr>' pebbles 1} in. in diameter along a sewer, and that a
of 0.7 ft. per second will remove coarse sand, and that a flow of 0.5
second will remove fine sand, allowing every margin of safety, it
i that there can be very little object in tnking so much trouble to exclude
washings of such paved roads. The author does not wish it to be
dcrstood that bo thinks that retainers and traps are generally unnecessary,

522

AMERICAN SEWERAGE FRACTJCE

but he csonaiders that there are very inaoy cases in which thtf Inpil

retainers might l>e imiitt^d witli advantage, and in which the oomjmr&tnf^ly
ftijp grid might be omitted in favor of a krger opening/* (H, S. WaJjuUt
* * iSc werage i^y at em a/ ' )

*'For these reasons the ujiiversiil use of natch-basins is* in the aiilhuf*
opinion J not to be advised, but ratlier the inlet should be so designi'd tHa^
all iiiateriibb shall at onee reaeh the sewer. The inlet connection h
also make without a trap, that it may assist in the ventilation of tlu
and if the sewer and Its ajip^irtenant^s are proiijerly designed, C5uri>!
and maintained there will be very few instanees where any odur
detected at the inlet.

*'The catch-lmsins should be cleaned after eveiy rainfall Theft
danger of putrefaction and objectionable odors from thc^o, if this is not <i
within two or three days uft^r each rain, but it is almost impmeticablflj
large cilies where there are one or two cjn everj' earner, without the u«! j
an enormouK number of men and carta, since each cart with three men t

clean but 5 to lo catch-basins a day* As an example of what i^j u«u

done in this line, a large city in New England, which is ccmsidered to luiv*
an excellent department of public works, during the whole of one year
cleaned its 1 lOtJ catch-basins an av^erage of 1.84 limes e^ich. It scents alaa?**
imposail>le that these catch-basins could hold the heavier matter wnsW
from the streets during six or seven months, or if so the small amount vtm-
tributed by each storm would have done little hartn in the sewer, and lh«
inference rs that a large part of this was not held, but was washed iat<»il»*»
sewer: ako that the eatch^basins were in an unsanitaT>' condition a bn
of the time. When .so treated they miglit better be replaced wit
inlets/* (A, Presoott Folwell, ** Sewerage/')

I n cities having smooth pavements and good sewerage >
been a tendency of late to look with favor upon the < i
surfaces by flushing. In fact, a number of wagons have been >^i •
designed for the purpose of forcing water under consideruble ph - ^^
over the street surfaces, thereb}'^ causing the same general effect that »
produced by tlie weak hose streanis used in s^oine European i
purpose. While a catch-basin does not aetuall}' prevent stri -^

by flushing, it is main feet that it is ridicidous to flush dirt into ^^
basins and then raise it from them at far greiitcr expense than \b r""^'"*'
to collect it from the street surface; where flushing is to be cmi
therefore, catch-basins shcfuUl be omitted.

They are certain to be used, even iu well- managed eitics^ as roe^'P^i'''''
for street refuse which should bo gathered otherwise aecordtng ^
nance. This was well stated as follows, by the MetropolHAii Sei^^^^
Commission of New York in ita report of 191 f);

"The men of the Btreet-cleaning department wash some of tbr ]
BtrtH*t5 in ccTtain sections of the city, and during this ofjeratitwj murh 4*^
is carried into the catch -basins. The custom of pushing Htre«»t jtwfxpd
into the bitsitia appears to be quite general; and| In fact, the bnAtiit* \

STHEET INLETS, CATCH-BASINS AND MANHOLES 523

popularly considered proper receptacles for anjrthing that will ent^r the

cntngis, tn eluding auow in winter. The report of the Bureau of Sewera

19<>7 states that 9674 burins were cleaned of snow. Although there is

i ordiniince HgniiiJ^t putting snow and street svveepiniass Into the basins, the

Ejistratca have invariably dismissed tht* cai^ea when the street cleaners

^ve been arretted on complaint of the Bureau of Sewers for violation of

' ordtniinw.H/'

While there is not the cr>'mg: need for catch-biisiiis at frequent in-
rvals which was formerly believed to exint, they have their usess where
[ is probable that large quantities of grit will be washed to the inlet and,
t this enters the sewers, it is likely to cause obstructions in them. If
Ile3' arc ased they should be cleaned whenever necessity arises. Clean-
should not be neglected until stoppage and the attendant flooding
5, nor should ba^iins be cleaned where there is little accumulation 'm

I '~Jr

Vertical Section.

Plan without
Manhole Frame.

Fia. 200, — Standard catch-bjusin, Providence.

bcm unless in localities where the nature of the deposit is such as to

ate offensive odors which may escape from the basin and prove a

Durce of annoyance to persons passing or living nearby. A basiu may

lit out of service automatically when it becomes lilled. This ia

[iplished by the old-fajihioned basin shown in Fig. 200, which repre-

int« a Providence structure. The feature of this catch-basin is the trap,

sediment colleets in the catch-basin it reduces the space available

pr water above its top and below the water line established by the lip

the trap* Eventually there will be very little water capacity, and in

immer, in prolonged dry weather, the water will evapcrate to such an

Ktent that odors may ari^e from the catch-ba^^ins. If no odors arise

l^id the cleaning gang does not reach the basin in its regular routine, the

iitnent will gradually accumulate until it overflows the edge of the

ftp^ blocking it. When this occurs the first hea\^ storm will give

524

AMERICAN SEWERAGE PRACTICE

undeniable evidence of the necessity of cleaning. In t}m way the Uup
serves a useful purpose by preventing the escape into the sewvr (rf Isxp
quantities of silt which might form deposits. Another advantage i>i' ^li •
baain, due to its trapj in that the water which q^cuniuktes in it ruh I
bailed by the cleaning gang into the trap and thug delivered directly inUj
the sewer, instead of being lifted to the top and thrown over th»'^tr>>'1
The great disadvantage of the trap is its liabiUty to freeze in cold w« :it n :
although it should not be forgotten that the air inside the sewpr?, uhiiii
will come up to the sewer inlet, will be somewhat warmer than (1j<'
outdoor atmosphere, and the sheltered position of the trap also hni* i^'iRi**
effect in reducing the danger of this nature. Where basins are coanof it"l
to storm drains there will be much greater opportunity^ for the Utrmt
of traijs. Like all attempts to use traps on catch-baains or inleti, the

J!^ of Curb

r I - - ? '

Vertical Section.
Fia. 201. — Standard catch-basin* Columhup.

permanence of the water seal b very questionable. It will pvafx*^**
during proloiigcnl dry w*eather, and it is idle to expect that a •o«i^
department will keep all traps fil!ed by means of a ho«e during **^'"
seasons.

The t>TDe of catch-basins used in Columbus, Ohio, for many*
S» shown in Fig, 201. It has two drawbacks, both due to thtj|
vitrified pipe for the elbow. It is difficult to believe thjit such '
elbows will witlistand the hard knocks given to them Avx -
tion of cleaning btis^ins* Thid is rough work done as •
possible, jincl everything within a catch-basin sliould bti
withstand hard usage. A second drawback to the bawitu
northern latitudoiS, is the possibility thiit ice will damai^e the A
The standard Xcwark catch-bajun. Fig. 202, 10 typical of tlia fonol

526

AMERICAN SEWERAGE PRACTICE

move shavings and dust from currents of air. The basin i» an
gonjjJ reinforced concrete box 17-1/2 ft, between the parallel sideiv i
plan, and 11-1/2 ft. high, and is covered with a tight top as shown
Fig. 205, from Eng, Record, Oct. 24, 1908. At the center of th«? Iwm

is a 2.5 X 3 ft. rcctani

K-— /V-" - - >|**-*/V£7*->l well which connects with tti

^%.u ! sewer. The top of this well i
25 ft. below tlie under su
of the cover of the ba^n.
Around the well is a ne»H
horizontal reinforco<i ooiicic
slab, which extends to with
6 in. of the walL^ of the b*
on all sides except the one 1
wfiich water enters; 00 ih
side it is carried out to Jo
with the wall of the b*
The upper side of t!m»bhl
12 in. below tho top of 1
welly and the alab 10 pit<
3 in. in all directions.

A 2 X 0.5 ft, inlet openti
is made horizont>ally in
wall of the basin to which 1
slab around the well is jo
The top of this opcnini? 1
ft. below the lower surface
that slab. Directly in it
of it a heavy prateitiou is 1
against the ailjacrnt ?id
the wall, to receive
of the water enttT
baain. This protection i*
the same width w^ the aid
the basin, and consistJi
maat) of coarse gravol
place by briok walk nl I
ondA, and on tho side \
the i-^
reinforced contjrete inclined at an angle of 6(1
is covered with a course tif paving bridt l»i»l
wlUeh the entering water impinges
tcction consists of very coania .

FiQ. 203. — Standard I'litt^h^bAsin^ Borough
of Manhattan.

STHBET INLETS, CATCH-BASINS AND MANHOLES 527

cipimingjs to permit the ordinary flow to escape through an open-
i the bfise of the well.

I? arrangement of the htmn is such that the force of the water is
in 9S it entei-s b}^ beiu^ tiirected against the iuclined stirface of the
ction, the hitter divi?rtin^ the stream to the right and the left, arul
rertically into the ehaml>er of the biisui under the slab around the
^al well. The only means for water to get from this chamber to the
is by passing up through a G in. opening between the walls of the
and the slab around the well; and thence up over a 12- in, curb at

Elevation,

/>ik —

— /^ • — — ^>tt<V'

MoriiontQl Section.

Pfatc for Hood.
Flo. 204.— Hood for Manhattan eatch-basin.

t Jto I

» thiit it drops into the sewer. The velocity of the water is
_ ally reduced at ouee, and the current is required to clian^ce its
^Wi of tlow at several points, so that all bouhJcrs, gravel and njost
Inposited in the chamber under the slab. Owing to the
1 flow of water, to pii^^s out of the chamber through the
the edge of the slab, only fine sand and particles
tiimI /ib»jve the latter^ Most of these fine materials are
!• of the alal), owing to the l2-uu curb which the
turmoual before reaching the well.

528

AMERICAN SEWERAGE PRACTICE

After each heavy storm it is generally necessary to remove sevml
wagon-loads of material from the basin, according to the article k
Eng, Record f published about a year aft^r the structure was placed in
service. This cleaning is readily done, it is stated, through two Mt

5ew0f ^ I

SecTion A-B.

Section C-D.
Fi(i. 205. — Ciitch-l)a.siii at Grand Rapids.

circular manholes in the cover. Directly under each of these is a 3-ft.
opening in tlie slab forniinp; the roof of the lower chamber of the basin,
which o[)eninjj:.s are normally clossed by covers held in place by eyeboltN
Tiirough these manholes it is possible to hoist the materials out readily,

STREET iNLETS, CATCH-BASINS ANI> MANHOLES 520

ving the time of two or three men for a day, Thiu \s much easier
taking the same materials out of a eewer.

special catch-basins adopted to intercept gasoline and oil com*

rom automobiles and motor trucks are disrusted in Volume II.

le materials used for catch-basins comprise concrete, brick and

if the relative merits of the three for any case depending almost

riy on the cost of the finished structure, since good basins can be

rurted of any one of them. In the Borough of the Bronx the 1913

ard details provided for all three materials, but it is probable that

B|^ cities there is not such an opportunity for conjpetition, for

Heconcrete or brickwork has an advantage over the other two.

feature of the subject is discussed in greater detail in the chapter

iv constniction of masonr>^ sewers in Volume II,

Bttngs,— For many years a great variety of castings was used for

basins and drains. A preicrence still exists for certain types,

North Berwick,

D- Frame,

1 '*^'^5?s^*?^S

^«**-

Mcrrimac. Concord

Fi(i. 20^, — Types of commercial catch-basin covers*

it is difficult to secure from an engineer a definite reason for

for some of them. For example, the Concord grate, shown in

has been used for many years in New England for inlets in

of streets not subject to heavy standing travel, that is to

iwhere the gutters arc not likely to have hea^y wagons drive into

unload their contents. Of all the grates, it probably affords

eel means fur the »torm water to enter the inlet, provided it

beeomc clogged with leaves, which experience shows have a

Irri.if lu V to accumulate. The North Berwick catch-basin is of

6S0

AMEBIC AN SEWERAGE PRACTICE

much the same type eiccept that the head id heavier aod then* u m
entrance for water aroimd tlie rim of the head. The D-pattcm fnme
and grate were long used in Boston, but recently a rectangiikr hxnw
haJB been adopted. There »eenis to be a general tendeiicy toward these
rectangular frames, of the geoeral type indicated by the pi-
Merrimac frame, Fig* 206, and that of the standard Philad-
head. Fig. 207. They have two decided advantages over types t
curves. The first is that it m practicable to keep the pavement ^-^
gutter in better condition with a square than a curved casting for it t«
rest against. The second advantage is that the grat« can be made «*
strong tm dejjired without much difficulty and still have a large a^^

A-

Plan. <*ff^

Section A-A. Section B-8.

Fia. 207. — Staudard irdet head, Philadelphia.

available for the passage of storm water into Uie inlet. Thr Bf^fouifc
of the Bronx aduptcd in 1013 a cast-iron inlet head shown
which has a curb opening as well as the gutter drain. WhaU , ,
adopted should afford an opportunity for securely bedding the /f*^*
upon the miu^onry of the catch-basin or inlet, for otherwise it v " '
loosened speedily and in rocking under passing vehicles it w
the pavement about it. The North Berwnck catch-basin fmi
for both IS and 24-in. inlets, the Concord grates are made for i .
irdotSt the Merrimac catch-basin frame is 24 in* scjuarc, measured oa wk
cover, and tlje D-fra«jo ha« a grate 24 in* wide and 26 in* kmf* *
some ca^es the cover i^ in two pieces.

1

tEET INLETS, CATCH-BASINS AND MANHOLES 531

fial from wliich the frames and covers are made m rarely
Ir specified. If anything ia said ubout it, other than that it

Mt^lron, the requirements artt rarely more definite than tliat
good qmility and make cuttings strung, tough and of even

532

AMERICAN SEWERAGE PRACTICE

grade, soft eaough to permit satisfactory drilling and cutting. It ^
not uiiusuiil to note a requirement that the metal shall be made witht*ut
any admixture of cinder-iron or other inferior metal, and «hAil 1*^
remclted in the cupola or air furnace. The physical test usually W
quired is that for the metal entering into cast-iron pipe larger than 12 m-
Ais a matter of fact, it is not likely that the metal of the^e trusting? **
e\'er tested or that there is any inspection of them at the fouiido'-
Certain foundries have become known as fumlshing good c^itch-ba^^
castiii^H and when they sublet such work to other foundriej* they hoW
up the quality of the prothict in order to protect their own f« r
There 13 a danger^ however, in such loo^e specifications, par ^
when a city calla for a large number of castings during a time of buain®^
depression. A foundry in a territory not ordinarily serving the city
may conclude that it can manufacture pwjr castings which will in®*^^
the apecifications well enough to make their acceptance legaUy nece.- -
and it can afford to send out such poor work, because it will protu-
never do business with the city again, owing to the freight ratea agai**^
it. Such a situation has actutdly arisen and was met by the refusal *^
the mayor and superintendent of pubhc works to award the contr**^
for the castings to the lowest bidder, a decision which at one ti*^**
seemed likely to bring them considerable newsi)aper notoriety of a ni^^"^
unpleasant nature. This danger can be avoided by requiring the c^^^
ings to meet the standard specifications for gray -iron castings of ^J^^
Americao Societj^ for Testing Materials. (See Volume IL) T^*
only additional requirements which are needed to makd them apS^*'^
to catch-basin castings are clauses related to the coating of the oaaiti*^^
and similar minor details. The coating employed is usually an ^**^
phaltum, coal-tar or graphite paint.

MAKHOLES

Although manholes are now among the most familiar featuroe t*^
sewerage system they were not used extensively until some time af^*-"^
many large sewers had been constructed* They were introducud ^^
facilitate the removal of grit and silt which had collected on the ui\i?^'^
of sewers having a low velocity of flow. Before that time, whi!*:* *
ecwcr became so badly clogged that it had to be cleaned, it wtun nr**!*^*'**
ar>" to dig duwn to the sewer, break through its walls, remo. '*^

strucfion and then close in the sewer again, ready to cause u, ^.. **^
trouble at a later date.^ The opposition to the manhotes secma to h^"*"*^
been due to a fimr of sewer air from thcm^ t«omri '

not surprising in view of the < 1 -rary accounts of

from defective dndns. The engineers of the L^mdun j)
succeeded in obtaining authority to conslrucl monholesi, wi

STREET INLETS, CATCH-BASINS AND MANHOLES 533

ble to prove that it was much cheaper to remove the g:nt from sewera
rough them than to break a hole in a sewer each time it had to be
mcd. It was not until later, however, that the value of manholes on
all sewers became reeognized, and the principle became established
It there should be no change of grade or aligimient in a sewer between
(intd of aceeaij to it, unless the sewer was large enough to enable a
^n to pass through it readily. There is one modification of this
|e which ha^ been yjermitted to mm^ extent in the last hO years, con-
of the use of a lamphole at changes in grade and more rarely at
in alignment. Some engineers omit a manhole when it is
than 200 ft. each way from other manholes, and subfititute a
.Jjimphole. Such practice has never been general, and the use of lamp-
lee in any situation is not regarded witli favor by most engineeif*.
fter the genend acceptance of the principle that manholes should
placed at changes in line and grade in small sewers^ there was a
ftdency for a time to go to the opposite extreme and put them in at
i fri*quent intervals. This is objectionable becTause of the unnecessary
Bt and the inevitable injury to pavements caused by the presence of
mhole frames in the roadway.
The earlier manholes were large stnictiires^ generally consisting of a
^kbt of steps leading down to the sewer from the sidewalk or the road-
^Ky near the curb, and entering the side of the sewer, Tliis position
^BH chosen because it was believed that the refuse taken from the sewers
^BuJd cause less obstruction to travel if removed at the side of the road-
Hky than along its axis. This was more important with the old sewera
^n very low grades, from which large quantities of grit were removed,
than it is today, when the sewers are on better grades and the amount
of grit entering them is probably less than it was 50 years ago. The
experience with these side-ent nance manholes was quite unsatisfactory,
lor during ev'ery period of storm flow the side entrance and the lower
ftp* of the manhole became covered with filth, which remained there
ben the sewage level dropped to its normal dry- weather stage, result--
[ in decidedly unpleasant conditions when the weather was warm. It
found that such manholes could not be kept clean so well as those
ring a plain shaft, with the sewage confined in channels in its bottom,
^rthermore, the actual obstruction caused on the surface of the
by the men engaged in removing material from a manhole was
ttd to be insignificant in most cases,

he great majority of manholes are constructed of brick, although under

Qc conditions concrete may possilily beuned to advantage, particularly

a large number are to be built, so that standtird forms may be

lixcd, or where the manholes are very deep, requiring considerable

sonry. The expense of procuring forms and the delay which their

f>aration frequently entails, the difficulty of placing them and of

534

AMERICAN SEWERAGE PRACTICE

placing the steps in the concrete, and the small quantity of concrete which
is used, usually make it more eeonomical to employ brick upon ordican-
manhole romtruction.

The manholas of small sewers are usually made about 4 ft. in dianietef
when of circular cross-section, or about 3 X 4 ft. when au aval cr<i»-
aection is employed. The same size is usually maintained for aU stwm
except when special conditions may require manholes of larger sisec, aa
when gaging devices miist be used at the bottom of the manhole, or it
is desired to have considerable storage capacity in the manhole chanihef
to enable this to be used to flush a long line of pipe on a flat grade. Brirk
manholes are usually btiilt of S-in. brieltwork down to a depth of 12 to 20
ft,, although until ret-ently the manholes upon the Cinciimati sewers imve
been built of a single ring of brick, and possibly this practice has hern
followed in some other places. Below the depth stated, 12 in. of hrick-
work is used as a rule. The aides are carried up vertically to within 3 ar
4 ft. of the top and the upper part i^ corbelled in or laid in the form of a
dome or reverse curve. These three t>T>ea of construction are shown in
Fig. 209. ^

In wet and yielding material, care must be taken that the unit pres'
sureB on the foundation of the manhole and the foundation of the ae^^^

Fio. 209.— Tirpea of manhole top«.

are approxinmtcly uniform, for otherwise there is danger of a settJj^
ment of the manhole, which will break the connection with the seW^
If the pressures are not normally the same, a spread foundation tnny
built to reduce the unit load imposed by the bottom of the nmnh«
When manholes are built in sewers having a diameter approximaleiy t ll
of the manhole, the walls of the latter are started directly from the «i
walls of the sewer, as shown in Fig. 218, In the case of brick sen
ring of brickwork surrounding the opening should be laid with ;»>«
approximately radial to the center of the manhole, so as lo fortiJ
cylinder to take the thrust of the sewer arch at t he point when* it m
away. As a general proposition, in fact, care should be dcvotctl to ti
junction of all shafts with a sewer, for the pressure of the s^urrouttdln
earth is Hkdy to bring unexpected strains on such ]u^
cannot be calculated with any degree of accuracy* Tlu* m
structure can be assureii by avoiding details which irill give an opjK^ |
tunity for the backfill in settling to impose heavy load* Ott brnr^'^^'*^ '"^

\eEET INLETS, CATCH-BASINS AND MANHOLES 53a

Inction where it k difficult to provide extrft strength without
dditional cost,

mihe sewer is much larger than the diameter of the manhole, the
^k the latter is usually tangent to one side of the sewer, for other-
^■1 be difficult to enter the sewer and a special ladder will be re-
|f reach the invert. When the sewer is very large, the whole
lie may rest on the steep side of the arch, and care muist be taken
d it with the latter carefully. This niay be done by having some
brick in the outer ring of the sewer arch and under the position of
&nhole walls project out half their length to act as headers. A
Dtal treiad may then be built up with these brick as a baae^ and
Mihole wall started from it. Occasionally, on very large sewers,
mholes are built entirely apart from the aewcr proper and have a
.eading into it, as shown in Fig, 210,

Arch Ban

aiSh^wff

I

SfcHort through Mortholc.
Fig, 210. — ^Manhole on large St, Louis sewer.

Longitudinal Section
on 5cwer.

I four manhole bottoms shown in Fig, 211 illustrate somewhat
|ty|>es of de^^ign. The Menii^bi!- and Seattle bottonih have flat
faces while the Concord anrl Syracuse bottoms have lower
wod to correspond with the channels thi-ough thorn. Which
s is best adapted for the soil at any site can only be ascertained
iition; the saving in material in the second type may be counter-
by an iiicreaseri unit cost. While the base of each manhole
! was constructed of concrete, as a matter of fact a good sewer
itty up brickwork to form practically any chatinel t.hiit may
^Jid can carry the work cm very expeditiously, if ho is so

in the bottoms of the Memphis and Concord manholes
prith high walU» the Concord channel behig nearly aemi-

mm^

536

AMERICAN SEWERAGE PRACTICE

ciroukr and the Memphb channel hardly more than that. On
contrarj^ the clianneb? of the Seattle and Syracuj^e manholof* i
high walb tliat they will carry all the sewage until the sewes
surcharged. It is now con?idered desirable to have the walla of the
channel rise nearly to the crown of the sewer aection, and then be stopj:
in a berm, which is given a slight pitch from the wall toward the chann^
The standard manhole used in Newark, N. J., for many yeara^ which]

Memphis.

Seattle.

Concord, «

Syracuse.

Fia. 211, — Types of manhok nivrrt**.

shown in Fig. 212, iUuatrated this form of conatruction carried » ***^
farther than is perhaps customar>% The «tandanl Phitac! *
bottom, Fig. 213, illustratea the method of giving a h
locity to the sewage leaving tho branchea, by pro\'iding a
the invert within the manhole.
Concrete manholei* have been u.Je<i in SyracuuM

ET INLETS, CATCH-BASINS AND MANHOLES 537

Two types have been employed. I o the firat type the man-
jnforced shell 6 in. thick* running up from the sewer to within

FtO. 212. — Standard manhole, Newark.

he ground surf acre, where a funnel-shaped top begins to cor?>e1 in.
Kment conaisti of I /2-in* rod* spaced 12 in» apart when

iS in, apart when Vertical, The other type of concrete
iOd ol reinforced concrete i)ipe placed on end. The see-

538

AMERICAN SEWERAGE PRACTfCK

tiona are 4 ft* in diameter and 4 ft, long, and were constructed like the
reinforced concrete sewer pipe used in the same city and described in
Chapter X,
The manholes built on the Winnipeg sewerage systemi of which CoL '

N. H. Ruttan, the city engineer, han bu^ri i f
are constructed of concrete rings 30 in* in
in. high, except the bottom four ring!^. *1 i
are split in halves to permit concrr * ^ '— i

STREET INLETS, CATCU-BASINS AND MANHOLES 539

ted ia the third,
^d, and fir$t ringed.
Hiring from the bot-
, Fig. 214» HO as to
Hhoti the lower por-
i of the shaft in the
Dtioxi of the axia of

r' and allow it
the monolithic
\ in wliich the invert
formed. This bat^e
an inside length of
, and a width of 30
and its walls are G
Jiick.

bnble manholes are
letimcs used where
sewera and drains
K> located as to make
D convenient. The
ptiire showTi in Fig,
' wa« used by the
■|^ for such a pui-
B^n the separate
l^rage system of
jedale* Mass. Each
fnber ia 5 X 4 ft. in
I and the dome has
fcplh of 4 ft. The
are 9 in» thick.

underflrains
kloyed it is some-
sired to aiTord
pm, and in
^yarioiis cx-
"Sre employed.
usual h to
Ihe luiderdrain a
flistanee to one
of the sewer, where
PMiea under the
nhihi and to bring
lo the floor
uj' luanitolct mn\(^

Section A- A

Section B-B.
Fto. 215.— Double manhole for separate avHttm

AMERICAN SEWERAGE PHACTICK

in the illustmtion of the manhole at the head of I
:<t mphoD^ Fig. 249. Where an undeTdraiii is dropped akM|
m ww^r. fls in the drop manhole ehowu in Fig. 219, som

provision for gi\ing access to tl
end as is there illustrated^ may U> pnv*
vided.

The Lovejoy combination nuuiholf^
quite largely used in B.
ciQity, is a patented -
in Fig, 216 and controlled by the UibOf
Foundry Co,, East Boston. Tlie t}m-

e|

^^U^^

1 ^MW 1^

T**

^^

5ect-ion A-ft
Fio. 217.— Drop taaobole* StoW

rop taac

\\\* i'hi !,*ncj\>v combination
\K\%\\U 1 1 W« , iS* t tu» ted ) .

H' . Aturr li the dcsiyrri is the sturni drain, erossing tiir

» ^'> 9^xKvt and provided with a large opening c!laM>d wilb

\ wtuch aui be hdd so firmly in place that there irill
m^ lv«4ik44^v at KhJ^ |oiut, even when the drain is surcharged

I

tfEi

STREET INLETS, CATCH-BASINS AND MANHOLES 541

Drop Manholes. — ^The drop manhole, sometimes termed a 'Humbling
basin/' has a mild historical interest as being the subject of patent
intimidation and litigation which was an annoying feature of sewerage
work in the Central States for a number of years. In 1892 a patent

Cross Section

Sectional Plan.

Fig. 218. — Drop manhole, Newark, N. J.

for the drop manliole was granted to James P. Bates, and assigned to
^exander Donahey, of Kirksville, Mo. Thereafter, whenever a city
adopted plans for a sewerage system with drop manholes, it was likely
to receive a notification of litigation for infringement of the Bates

542

AMBRfCAN SEWERAGE PRACTICS

patent anless a license fee, tisuaJl}' $10 per manhole, was paid
sum deimuided was so small that thjg city eounsel usually adviml i
payment, although city engineers istrongly fought against it i&
courts. Finally the city of Centerville, la., decideil to ttssl llw imltl
and refused to pay a license. Suit was brought, hut on April 1ft, 19
the IT, S, District Court sitting at Keokuk, ruled, b<*fort^ thi? A^ft:^
had introduced its testimony, that the drop manhole had no patents
features. That ended the matter.

The drop manhole shown in Fig. 217 was constructed <in li 6 ft 01
X 4 ft. 6 in. sewer on St^ten Island. It has a 20-in. east-iron
imbedded in concrete, for the fhy weather flow, and it will beob

that the general arrangement b
such that even in tima* of heary
dbcharge the flow ilnwD Hii»
drop pipe proba Vily so r
a cushion at the boti
manhole, io rec^ve the btitk]
the etorm-water flow. Il
l>e added as a matter of int
that on one sewer on Stateii
land there are 29 drop i
in a length of 7883 ft, Hf . \
shows a drop n\ > ' ' bi
Newark, N. J., wh tl

usual on account of its id
at the head of a large oval '
sewer 4 ft. 3 in. higli, itilo mh
two circular sewers diarl]

Fig. 211). ^Double drop iiiaDliole, Med^ different elevations.

ford, Mass. manhole shown in Fig. 219, i

constructed at Medford, Mi
under the direction of T. Howard Barnes. In an article in
ginecririg Rccani, Oct. 30, 1897, he stated that the sub-flrain ioopff^
tion hole had been found very convenient. Frequently it gervcd ^
times of making connections with constructed work, aa a w^l tk
which to lower tlie adjacent ground water. A still niari ^
of drop manhole and underdridn overflow is shown in :
was constructed on the sewerage system of Newton, Moto., ir«inl
designs of the late Albert F. Noyes* The drop takes place tlirou^^
sheet-iron funnel and pipe. The bottom of each standard manh»li*(i
the two sewers shown in the plan has a central o|' nti

underdrainj with the channel divided and passing arou;
in twin inverts, a type of construction which was introduced la '
other places by this engineer.

a^i^^iib

544

AMERICAN SEWERAGE PRACTICE

Surface ; of Street .

Fig. 221. — Wellhole, Morgan Run sewer, Cleveland.

STREET miETS, CATCH-BASINS AND MANHOLES 545

|Wellholes. — Deep manholes in which the sewage is dropped a

siderable diBtance from one elevation to another are sometunes caUed

>p manholes, although that name beJongs to the type just described,

are more frequently t^Tmed *' welllioles." Fig, 221 show^ such a

jcture on the Morgan Hun sewer in Cleveiand, a city which has had

siderable experient'e with these wellholes.

L wellhole 65 1 ft. deep from the surface of the ground to the bottom
the invert^ Fig, 222, waij built in 1893 in Petrie Street, Cleveland,
iifc^'here the roadway wa** carried on a ver>* deep fill. In order to check
velo<nty of fall of the sewage the latter dropped at intervals of 5
on atone flagging, having a thickness equal to that of two courf*es of
ck^ placed as shown in the illii**tration. The connection from the
3m of the manhole to the Wt. culvert, was of a flexible cliaraoter,
indicated in the skcti-h, owing to the probabibtj^ that there would
some settlement under the fill in the course of a few years. After
iiB settlement had occurred it was proposed to calk the joints of the
connection thorouj^hly from the inside. Whether this was done cannot
be learneti but the structure serv'ed its purpose satisfactorily for about
[10 years^ when it was abandtmed on account of the rcconstruetioo of
Petrie Street sewer.
Some very doep wellholes have been constructed at Minneapolis^
; connection with the sewers built to chtx^harge .^torm water into the
wiAsippi* The greater portion of the citi,' serv^ed by these sewera
[from 80 to 100 ft. above the river. Along the river bank is a drive
. park which make it neceasar)^ to build the wellholes some distance
&m the river. The typical wellhole shown in Fig. 223, from Eng,
rord^ April S, 1911. is 340 ft. from the outlet, for example. Where the
is tlirough hard limestone the section in not lined but given a funnel
ftpe, which i? advantageoas in concentrating the sewage in the center
I the lined portion of the wellhole. This latter has a lining of ^ano-
Jiic block in a backing of concrete, and I he outlet sewer from it starti>
, an elevation wliich gives a deep sump in the bottom of the wcUholc,
ling a water cushion to pre\'ent erosion of the lining by I he falling
kters.
)a some of the tunnel sewers in the Borough of Brooklyn there are
inholes from 65 ft. to 83 ft. in depth, P^ig. 224, into which sewers
rgo at dlstance>s of 25 to 40 ft, above the invert of the main sewer
Below these shaft manholes the invert is paved with granite
cka laid in Portland cement for a dis^tancc of as much as 30 ft.
rthej-more, althotigh the trunk sewer Is in a tunnel at this place, an
Ira heaN-y bottom is constructed below the shaft and manhole for a
Kth of about 14 ft.

The use of drop manholes and other special details to give a sudden
9p in grade la not regarded with favor by some designers. For

9d

AMERICAN SEWERAGE PRACTICE

Tbp5tf>ro£tftnd
E^fyonal Center ^

Plan, Section 6-H.

Fig. 222,— Wellhaie, Petrie Street e**wer* Clcvclniiti.

STHEET INLETS, CATCH-BASINS AND MANHOLES 547

pie, W. W- Homer, of the St. Louis Sewer Department, stated
tide in Engineering New$^ Sept. 5, 1912, that **the tumbling
atroduces unknown factors into a sewer system, which we now
best to avoid, if possible. It is questionable whether the basin
lly acts to advantage under extreme conditions. Such construction
rery expensive, for if the sewer ia deep enough above the basin, it ia
I deep below, involving excessive excavation; also, if it is supposed to

£f./oeM

SarftbtonP,

Fio. 223.— Wellhole, ^finneapoUs.

*'lt the velocity, much larger sewera are required for the flat grade.

•he pfc-^erit practice (1912) is to design the sewers carefully at all points

■ M to tjike advantage of all the natural fall, in order to decrease the

B^ of the i^wem; then to build them strong enough to take care of the

^'^tiltin^ high velocities.'' Where sewern are built in deep rock out,

l| "*e kit\\ (u^t of excavation has frecjuently led in »St. Louis to the adop-

f;ular crossj-section for the sewer. By making the sewer

: ti the amount of excavation will be materially decreased,

548

AMERICAN SEWERAGE PRACTICE

but a8 the ratio of the height to the width increases, the section 1
comes less efficient from the hydraulic view-point, requiring a gre^^
wetted area for the same capacity. A number of conditions nm^
be f ulfiUed in such cases, and the best section can only be obtained l^^
number of trial calculations.

^3S*^

^^^^^^^

Cross Section. Longitudinal Section.

Fi<}. 224. — Wellhole, Borough of Brooklyn.

Flight Sewers. — A considerable fall must sometimes be provided in a
sewer, and while a drop manhole or wellhole always affords a means of
changing grade sharply, the lower sewer w^hich leads from such a shaft

560

AMERICAN SEWERAGE PRACTICE

may be so deep that any prolongatiou of it should be avoided U i\
expensive structure can be made to serve^ The flight sower, whidi |
its name from its resemblance to a flight of stairs^ in f
in such situations. It has a steep grade, but steps in th
check the velocity of the current; the resistance they offer profci
diminishes with the depth of the sewage, and if the descent Is lonir p
care should be exercised to ensure massive, durable construction an'ifn^-
dom from olistruction to flow at the bottom of the flight, wi '
seriously strained if the sewer should ever run full. Two <
such a sewer are shown in Figs. 225 and 226, from Eji^nterin^ R((M
the first has a small circular channel within the concrete base to carry tlir
dry-weather flow while the second has no such proviaion.

The flight sewer nhown in Fig. 225 is a part of the Indian Run ?ewff
in Philadelphia. The total length of this special section is Gl ft,, 4a(i m
that distance there is a drop of 24 ft. 8 in. The granolithic finissK of tlni

Bcction was a mixture of one part cement, one part ^and ar; ^ - "*

granohthic grit. On the risers this mixture was placed agar

of the forms in advance of the bulk of the concrete filling.

was at least 1 in. thick in ever>^ place. After the forms were r l .

face was at once brushed with a thin plaster of equal part^ of aand vd

Portland cement.

A chop of 15 feet is made on one of the sewers of Baltimore by'i
of the flight sewer shown in Fig. 220. This sewer is ne^r the high :
reservoir and in tliis vicinity there is another flight sewer of 10 ft, <

Special Manholes. — Angle weils arc occasionally used on large i
ducts under light to moderate pressure^ where it is impr;'
at excessive cost, to ]:>ut in horizontal curves lilting the U r ;
60-in, pipe line laid in 1912 by the Denver Union Wat^^r Co., for rx
four of these wells were used (Bug, Record, Jan. 18, 1913), wbu.
angles were 27° 8', 33^ 35"" 27' and 20'' 28' respectively. They wrt S I
in diameter, 10 ft. high and made of 3/8-in. steel, and were helj
by eight 1-1/2-in. anchor bolts attached to angle fasteners rivet
sides. In addition to providing change in direction, these wdU ^
expected to act to some extent B& aand-catchers, as they extends
below the bottom of the pipe.

The gaging manhole shown in Fig. 227 was built at
from the plans of Wise & Watson, of Passaic, in 1900. i
provided with a triangular weir, which is rather unusual in Umt I
an equilateral triangle rather than one having a top width twice it
height. The hitter shape has been adopted mainly iis a re
periments made by Prof. James Thomson and reported in ih^ !
Association Report, 1858, page 133, and of experiments by l*raf.
Porter at the Massachusetts Institute of Technology, At tJie
time there is need of some accurate invostigation of the dbetmiEf 1

STREET INLETS, CATCH-BASFNS AND MANHOLES 551

Iter through triaiiguhir notches, for the uncertainty regarding the

bject prevents their iise in gaging small flows where their form would

te then> particularly applicable wt^rc there greater certainty re-

rding their re^iiulti?. Further information about this weir was given in

n IV.

formation regarding other forms of gaging raanlioles is given in

^pter IX, on gaging stvorm- water flow in sewers*

I A manhole for an unusual purpose is illuHtratod in Fig, 228, from

%g, Rccttrd, Aug. 28, 1909, aod it also is of interest in that it is one of

very few structures where life has been lost owning to the poisonous

|eet of sewer air. This structure is at the end of the Los Angeles

ver outfall where ft discharges into a wood stave pipe that carries

WrougM4ron Frame.

HofJTon+ol Section*

Fig. 227. — Gaging nmuhole. Liberty, N. Y.

tic aewage 000 ft. out to sea. The old sewer outfall was badly
siategrated in places by the sewer air, where it did not run full, and
tiis gate chamber was designed to keep the lower portion of the
[>nduit under a slight head. It has a gate across the main central
innel running through it, and on each side of this channel is a dara or
^eir. By clcjtiing the gate the sewage is forced to ri»e and find an outlet
^'or the crests of the two wiers. Que of the engineers of the city lost
l^s life in 11)09^ in manipulating the hand w^heel by which the gate w^as
ed and lowered. With a companion he mm^ed the gale a number of
Imes, and the companion reported that whenever the gate waa near its

552

AJdERICAX SEWERAGE PRACTICE

fieat live violent rush of aewage bdow the bottom of the gate f^vedf
gases wbieli caused extreme dizzinesE. They were se\-erai ^mes fornd
to come to the inirface and he down; the engineer lost his life on one
of these oeca-^ions. Instead of leaving the manhde he stood par%

Lower Half I Section on C-C.

Longitudinal Section A-A.

Cross Section B-B.

Fi(i. 228. — Gate manhole, Los Angeles outfall.

out of it, his arms resting on the manhole frame and his feet on the
ladder. He wa.< suddenly seen to drop, and when his companion
hurri(id to the gate chamber his body could be seen resting on one
of the steep side inverts, from which it slipped into the wood outfall:
a few days later it wa.s found floating in the water.

TREET INLETS, CATCH-BASINS AND MANHOLES 553

^^f

:use.

Brooklyn ^
Fig. 229. — Types of step forgiogs for manholes.

Vertical Section.

Elevation.

t" 7 V-

f-U.^?.^

,

Sectional Plan.
Fio. 230. — Cast-iron box step, Boston.

AMERICAN SEWERAGE PRACTICE

Crou Section.

Manhole Steps. — ^In shallow manholes, steps are sometirDes formoi
fcy lea%ing projecting bricka at the proper poixita^ about 15 m, apirt
vertically. Tto ia an old practice and while not appr
engineers, haa been in more common use than axiy oi
construction until quite recently. The steps are objectioDabIc boottiK
they are sonietimes slipper}', when it is difficult to u»e them ea/e^i
and, moreover, they are subject to breaking.

The iLsuaJ methml of providing steps at the present time is to con
them of forging^, which are bedded in the brickwork or concrete. 1
types of these steps are shown in Fig, 229, Sometimes stqw m
formed by straight rods inserted in the masonry in such a way as to
form chords of the brickwork ring, with the center of the step at kafil
4 in. from the brickwork. The !itept« are asually placed from
in. apart vertically and somewhat staggered; a number of cities i
be in favor of a vertical spacing of 15 in. The authors have fouiwi t

step of the type mai'ked "S>t

— -TO| cui»e" in Fig. 229, .sattsfartwnv

^ experience with it indic^t^s

the blacksmiths who forge t!ie s
must be cautioned to fallow
dimensions iiccuratelVt for othc
there will be trouble in littijtg Xk
ateps into the joints of the brid
work. Fig. 230 shows a caat-ii
step used in Boston where the >
miLst be kepi free from any prtyo
tions from the wall.

Manhole Frames and Covers-—
There is just as great a variety in
manhole frames and co\'cni a* tlww
is in the castings for caich-biKBW
and street inlets. It is gnulually
becoming evideot, howe\xr, th*t
certain conditions should be fulfilled in the design in order to get
best results. For example, experience now indicates that the oiH
face of the frame should be vertical from bottom to top and l>e wrt!
projections, for a blank surface of this nature enables the pav
resting against it to show a little better resij?tanoe to wear than w Uir
case whore there are projections at the top of the frame ot tiie btCtf
has a broken surface. Again, the practice of makins? the covon* r»lh«r
deep and having a pocket in iheir top, in which lisphalt or wood bloi
is placed, once much favored, is now (1913) regarded with muoh \\
favor by city engineers, who are reoommonding instead a caat iron
with the surface broken by a shallow pattern of »ome sort which

Fio.

Plan.
231, — Cast-iron manhole step.

:ett^
iitt»^H

eflacflfl|

STH£ET INLETS, CATCH-BASINS ASO MANHOLES
9

555

556

AMERICAN SEWERAGE PRACTICE

give resistance to alipiiinjs; when haracs step on the castings, nr*l|
prej*ent tendency ia undoubtedly toward somew^iat heavier and sdmpi*
framea and covers than were used at the be^iuning of this centu:T'>''-
This in w^ell shown in Fig. 232, illustrating tfie standard msLn\^<^^
head and cover Manhattan, adopted in 1912. The head haa a minim u^
weight of 475 lb, and the cover 135 lb. The cover is raised by insertix*i?j
the end of a pick or bar in the recess^ C, The atandard cover «wi*^
frame used in Phihidelphia are shown in Fig, 233. This has an opening
of practically the .same diameter a.s the Manhattan frame, but woigli^
very much leas. With a ventilating cover, in which the rectangle^
marked V are left oijen, the weight of the frame and cover, together, i^
340 lb. ; with a closed cover^ the weight is 365 lb. Thin cover is raised
by means of the loose linka^ which are easily lifted from the grooves in
which they rest.

With thia frame is shown the wrought-iron bucket used below t!
cover when the latter ia provided with openings for ventilation. The*
bucket is constructed of jVi^* galvanized iron and has three lugs by whick
it i« held in place in renesses in the ring of tlie frame sujiporting the cmi
Tlie bucket can be lifted by mean« of the two bent hantUes. The bi
torn contains a number of half-inch holes, to allow water en
through the ventilated cover to drop into the dewier. This methi>J
allowing water to estmpe has been found in some places to permit
escape also of most of the dirt which falU into the bucket^ for it is
the form of very fine powder in such cases, and b not long in fintling
way down the manhole into the sewer. Where the refuse to be cai
is coarser than duiit, the perforations in the bucket are leaa criticized by
engineers wlio have tried them*

The use of ventilating covers is considered necessary by some
neers w^hon a network of sewers is first constructed luid thei*e one fi
house connections \^ritU it to afford ventilation, Aft^r the *ysl*»m
been in service for some time, there seems to be a general U
use closed covers on a considerable portion of the manholes an,
tlie open covers only where the need for them is evident* The openii
in the covers are oftxsn closed with oak plugs, but the authors have foul
that the best way is to have a bltwksmith plug them with rivcbi.
teuipts to fill them with cement or an asphaltic mixture are not sm
ful for any length of time, as a rule. In some cases the manhole con
are provided with grooves for a slide below the perforated portii
and when the cover is to be closed the slide la inserted in placet

^tn ft Ivtier from Goorai* W. Tlllion* Ccmsulttitjc Eug. to the E<^rmt«:h of Bt^
ilm d<s«ire of the wtreei dep*rtmetit ntficiftU Wft*i nUt«d t-o hno i* vovrr "vrbiclii wiU j
am bttl« obfktructiofi to traffic *» puM^btc au<1 intiLTfrrc Uie \cu»i »tUi U>e eotiAli
the pavcmaot A bond withfiui » line pxmltvt lo traffto in prfdrrv^hl*. ji« witb I
whtab hjive a liiw psmUttl to the tiuts of traJAo, rut« Are ll»bt« to ti*rm, **

fREET INLETS, CATCH-BASINS AND MANHOLES 557

f^ . — ^^

558

AMERICA!

Image practice

the bottom of the holea, which are then filled with grout or an equivfl
material.

Just how much rain-water enters through the perforations m
covers is diHieult to cBtimate, because of the fact that the ground-wa
level and the leakage into the sewera generally rise at about the
time as the maximum flow may be exjiected through the manhole cove
Just before the joint outlet sewer in Northeastern New Jersey

23^' ,,

$T

Cro&& SecTton.

Top Plan,

2i piom.
Liftirtg

Top Plan of Cover.

J^^fhkr

Bol+om Plan.

Fio. 234. — Syracuse frame and
cover.

AoWom Plan of Covc^.

Fio, 2:i5, — RiHMiklyn framo i
cuver.

completed, there was a very heavy storm. There were 125 mili
sewer in the system at that tinie, and about 1905 mauholea having v^
lated covers. No catch-basins were comiected and no roof wat«r|
supposed to be admitted. According to tlie cliief engineer, jVle
Potter, as nearly m could be ascertained 3,LK)0,(J00 gal.
the S3*stem iti 24 hours throncfi thes*^ cuv»rj^, or an ir\
per minute per manhol

STREET INLETS, CATCH-BASINS AND MANHOLES 559

The standard manhole cover of Syracuse, shown in Fig. 234, re-
[Jt-H timt used iti New York, except thiit the perforations of the
. iTH are much more numerous and only half as large, and the aurface
an entirely different pattern. Tliia pattern was long a favorite,
»ut has recently been criticized by street department officials as more
•lippery Ihaji that shown in Fig, 232. It is also used in the very
l^mjrfe nmnhole frame and cover shown in Fig. 236. illustrating the

Lifting f

¥ M'

f frame

Ufttffg Kty

Manhok
from§.

I

Ftn. 2*i5.— Xiocking device for manhole or catch-baain cover, Boston.

ttfttingj* used at the top of the wellhole shown in Fig. 224. It will bo

iWrttd that witii »uch a large cover the casting is made in two parta*

The Kwking device for nmnhole and catch*baain covers shown in

': 2Ii6 vvsw designed and patented by R. J. McNulty, mechanical

i^iiJliiieer of the Hewcr i^ervice uf tJje Bojftnn Public Works Department.

lilt* lock t^ a in>t-iroii dus.^ hung loosely on a pin, with a lug projecting

i^&i

560

AMERICAN SEWERAGE PRACTICE

rearward to engage the underside of the ledge of the manhole frame.
The dog also has an arm projecting forward to form a closure for the
opening in the cover. Beneath this arm are three ribs, between which

A-4* —

r

Plan.

\pust Box g "^p
^^S2ESZBSS0k 1

V— 7/'-— Si--'- 2^'- -J!

K-- ~ ^74^- J

Section A-B.
Upper Half. '^'''^^^ f

Details of Lid.
Fh;. 237. — Ventilated manhole cover and frame (Kirkpatrick).

arc pivoted two tumblers so shaped that gravity causes them to u
normally under the ledge of the cover. It is then impossible to ^V!
the cover because the tumblers engage the ledge on it and preveo*^
lug on the dog from disengaging the ledge on the frame. The uiuoeK*

THEET UNLETS, CATCH-BASINS AND MANHOLES 561

J accomplished by inserting the two-pronged lifting key through
Itiecial hole in the cover, turmng it ISO deg, and then lifting it,
li will lift the tumblers and dog^ allowing the cover to be removed,
ii tlie cover ia replaced, the dog and tumblers fall by gravity into
ion and lock the cover automatieally. The cover cannot be un-
>d with a bent wire, like many locking covers. Many of this type
laed in Boston to prevent the dumping of mhes and other refuse
manholes and Avhere the displacement of a cover would be particu-
dangerous to tratfic.

,6ctk0tfyr locking Cffifer

.*7op af Bottom Stcii^fi

Fig. 238* — Adjustable manhole frame (patented).

of ventilated manhole cover and dirt box, uised in a number
p gyatoniJ*, designed by Walter G. Kirkpatrick, b shown m
The designer states the advantages of thi.^ form aa follows, in
i'«, Aug. 26, 1900:

iujit box is dura! tie, easily cleaned, cannot drop itaelf nor it« con-

th^ »cwor, and allows easy access to the ruauholc and the scwor

; id«o th« casting is immovable on \\a setting and present* a neat

on the fitrcHit, It \s^ designed for either paved or unpavcd streeta

it fitr«et traffic."

562

AMERICAN SEWERAGE PR ACT WE

Mr* Kirk Patrick stated that the cost of the additional weight due to
the du8t box was but little more than that of a sheet metal dust paa, and
the cast-iron dust box he regarded as much more permanent and con-
venient. The average weight of the frame and cover was about 425 lb.

For streets where hea^y travel wears the jiavement rapidly, an adjust-
able manhole frame which can be readily made lower is desirable. A
form used in Boston and its \dcinity is shown in Fig. 238; it was dcHignot
and patented by E. 8. Dorr, Chief Eng. of Sewer Service, Boston Public
Works Department. The frame is in two cylindrical sectionis. The
bottom section ha^ four steps in its wall and the top section han a serite
of inverted steps cast around the inside of the cylinder. The frame caii

Plan.

tHote f^rtock

j\Co.err^

Handle

,MaltfwLO€k

Vertical Sec-r*on.

Fio* 239, — Loeked manhole cover, Philadelphia.

be lowered 4 in., in four drops of 1 in. each. The bottom 8e<*tif>J*
attached firmly to tlae mai*oar>* of the manhole while the top
prevented from turning by a lug whicli ia held fast by the pu ^
It is stated by C. H. Dodd of the Boston Sewer Service that in -
cases concrete manholes are finished with two courted of h*
masonry at the top^ because this makes it easier to adjust mttnl**^
frames to the changes in elevation of pavements which occur fi"
time to time- Chipping off the top of a concrete manhole r.»r tW
purpose is a tedious process.

It is sometimes necessary to lock the entrance to a n "
certainly than can be accomphshod l>y any of Iho catches
one time ui'ed to some extent to prevent the romovid of the coic
cover for the purpose is shown in Fig. 2 ?<* ^* '- -r-^^! "» *^'' ♦'

STREET INLETS, CATCH-BASINS AND MANHOLES 563

hole, in Philadelphia^ la which a gaging machine is kept, and imme-
itely on top of it rcsta a manhole frame and tight cover of the type
trated in Fig. 233. The cover is a circular plate 21 in. in diameter,
IB carried by two flat wrought-iron bars j in. thick, which are bent
each end. There is a J-in, hole for a Yale lock in the end of each
iliaTi which ia bent up to fit into a hole cut for the purpose in the cover.
A watertight manhole frame and cover, designed for the sewerage sys-
tem of Concord, Mass^^ by one of the authors, is shown in Fig. 240.

W

Plan

SecHon t"F.

240. — Watertight manhole frame and Fio. 241.^ — Wttterfight man-
euver, hule diaphragm.

No detailed explanation of thin design it necessary, except that the brass
bolts were equally spaced no that the cover will fit in any of four possible
positions. Fig. 241 shows how a manhole frame and cover of this type
irer e used inside a manhole in LouiTv^ille, where it was necessary to
^HYide againat tlooding neighboring lands with water from the sewer,
flmen the river into which it discharges is at a high stage.

Laxnpholes. — It lias been intimated already in several places that
the authors have not found occasion to use lampholes on their work. In
whore they might have been employed, it was considered that the

■

564

AMERICAN SEWERAG)S PRACTICE

additional cost of a manhole was well warranted by the iuliranta«{i tf
accesaibility to the sewer which it presents. It i§ true that by mem
of mirrorH attached at proper angles to a rod lowered into a Uropliii^
with a good light reflected down the lamphole by th© mirrors^ it U \u^'
to see something of the condijion of the sewers in its vicnnity. The hlh:
use of those shafts, howe\'er, is to enable a man to lower a light of suiut ?*ri
down into the sewer, so tliat an obaerv^er stationed at ii iDAnhok m
either aide of the shaft can inspect the interior of the pipe. It is fri-
quently stated that a lamphole can be used for flueihing, if a hcwft cut
nected with a nearby hydrant is carefully lowered down it; thisi
true, but the aulhore have never heard of a case where it wan thn
their opinion, the best views in this and other countri&s
lampholes have been well summarized by Fruhling in l\ig i **.
der Stadte,*' in the following words:

"In order to economise in maiiholea these oftentimes alt«nialfi with licip*
holes, which are cheaper to construct and sufHce to eiiabto Uie ikjw »( iht
sewage to be observed. This cj^n be done either hy hiaking down thccMl
after removing the cover, or a lamp can be lowereti down t1 ml <m&

be observed from the nearest manhole^ either directly i>r v. il J*

mirror. In must cases the character of the flow will afford ixilursuitidD
whether ever>^thing is as it should be or a clogging han ari«»en« and whftbff
the cause of the latter is above or below the lamphole. The ohstrudww
are removed from the nearest manhole, for the lamphnio pennite oalyj
ver>' slight means of ingress, such aa the introduction of a hose, ^ Eirl
the diameter of the lamphole is concerned » from 6 to 10 In, is rocnight i
<'f»r(ling to the depth of the aewen The shaft consist* of irtlrtfitd fUy.
concrete, or iron pipe, and more rarely masonr>% The fmr,
the top are to be placed in the roadway so that the weight r^*
does not bear on the shaft, which wonUl transfer it to Ibi ; 1 1 •
lamphole is at a place where a flat grade changes into a si« t !•< r ri
should have ventilating holes,"

la addition to what is stated in this quotation, it is
emphasis on the necessity of avoiding any weight on i-^
pericnce shows that even the weight of the riser pipe forming ilie ^di
will sometimes break the sewer pipe from which it riacs. The dtttstfto*
experience of this sort at Memphis, mentioned in the Introdirtiai,
has been duplicated at many other places* Consequently- the fmw
and cover, which are made like small manhole castings, should be laniKi
by a ring of concrete or masonry surrounding but not louching tk
vertical pipe. Even with such precautious a lamphole i$ boimd Ni ^
a source of structural weakness^ and iia use ahould be
if poflsible.

CHAPTER XV

rCTIONS, SIPHONS, BRIDGES AND FLUSHING DEVICES

Jtmctians* — The earli^t discussion of the importance of eaay curva-
re and of carefully guiding together the streams of sewage at a
|r»c5tiou, whieli the authors have fmmd, appears in the report of
British General Board of Health of 1852, where Roe, best known
his table of the areas drained by circular sewers of different
imeters, made this statement :

** Every junction, whether of a sewer or drain, should enter by a curve of

iffident radius; all turns in the sewers shuuld form true curves?, and as»

jrcn in these, there will be mare fricticm th^nn in tlie straight line, a small

Idition should at curved points be made to the inclination of the sewer.

■inay mention a case or two in illustration , In 1844, a great quantity of

lin fell in a short space of time, overcharging a first-size sewer and fltmding

|tich property* On examination,, it was found that the turns in the sewers

ere nearly at right angles, and also that all the collat'Cral sewers and drains

ae in at right angles. The facta and suggested renjedy were reported to

Holbom and Finsbury Cotnmiasionera, and directions given by them to

out the work. The cvirves and junctions were formed in curves of

> ft, radius^ and curv^ejs with cast-iron mouths were put to the gully-chutes

tkd drains; the result was that although in 1846 a greater quantity of rain

in the sarae space of time than in 1844, no flooding occurred, and smce

en the area draining to this sewer haa been very much extendcfl without

anvenience. In another case flooding was found to proceed from a turn

1 right angles in a main line of sewers. This was rcme<lied by a curve of

\ ft, radius, when it was found that the velocity of current was increased

Dm 122 (as it was in the angle part) to 208 (in the curved part) per minute,

l^th the same depth of water."

jfith small sewers which it is impracticable for a man to enter* the

ges in direction as well as grade must be made in manholes, as

ly explained^ or at lampholes. If this is not done there is a risk

a stoppage occurring at some point where it« location cannot be

curat ely determined, and if such a thing occurs the only remedy is to

down through the street to the sewer. By the time the obstacle

been removed, the sewer repaired and the trench filled, the deeira-

lity of avoiding such occurrences in the future will be entirely clear.

' Wliere the sewers are large enough to be entered, so that their junc-

HOi do not need to be made in manholeSi and they come together with a

565

tfmft*

^gggH^

JUNCTIONS, SIPHONS, BRIDGES, ETC*.

567

oriisantAl angle between their axes less than about 30 deg., a special

iiciure called a junction is required. For many years these junctions

re usually of the type shown in Fig, 242, and were called '*bell-

poulks" or '* trumpet arches," The two sewers are constructed as

idepeudent channels until the outside lines of their masonry come

Ogcther at the springing Line of the arches. If they were continued

yond this point tas independent arches, the tongue forming the

ipport for both arches would gradually become tliinner and tliinner,

ad the roof of the junction would consequently be in danger of falling

arough lack of supporting strength at this point. Eventually the

&ngue would become so thin that even the most reckless buildexs would

7t try to carry the roof upon it. Accordingly where, at the springing

the outside of the arches come together, no further attempt is

to have the upper portion of the coniiuent sewers independent,

xt a large arch is thrown across the two. At the highest point of this

rch, just in front of the brick wall which closes the large end of the

ructure* a manhole or ventilating shaft of some sort is frequently

pected. Great care should be paid to forming the curv^es of the invert

the correct lines, because at these junctions there is frequently some

oentation, due to backwater, and the inverts should offer no ob-

nction to the wasliing away of these deposits by the first storm that

The structure shown in Fig. 242, was built of brickwork, but bell-

aouths are frequently constructed of concrete. Where brick is em-

loyed and the masons are experienced men, the construction of one of

liese junctions, even ^hcn more complicated than that illustrated, hs

ot a difficult task; while the centers must be strong, they do not require

be carefid finish of a form for concrete, such as that shown in Volume 11^

^liich was used on a structure in Louisville. In any case, however, the

rpense for one of these bellmouths is largely made up of skilled labor »

lithcr in laying the brick or in making the forms. To avoid, so fiir as

siblc, any furttier increase in these items, some engineers have re-

&ntly turned to flat-topped junctions.

A ftat-topped junction constructed in Pittsburg is shown in Fig. 243.

; ia a structure which is more ex|>ensive to build than most of the same

Bneral tir^, because it was inserted on an existing brick sewer of large

Kc, which it was desirable to disturb as little as possible. This was

iered more easy from the fact that the sewers come together at an

Bgle of about 45 deg,, which renders unnecessary a long tongue at the

action of the invert. The roof, in this case, is a reinforced concrete

lib, and tiie manner in which the old brickwork has been surrounded

Hth concrete, so as to utilize it as fuUy as possible, desen'es attention.

be »harp pitch given to the new sewer, where it joins the large existing

568

AMERICAN SEWERAGE PRACTICE

■Mr^-%i^^^

s* fe~ii-7/^ -"■■■■■ii'J:^

•4so dascrvcs attention, and thia feature of design will be rcforr<Ki
Ic later,

W Krre flatrtoppcd sewers are neceasaf}' at junctions^ and the aiiglr
^nrl^icli tha axis of the two confluent sewers make ia small, it is now
^%i»tomafy for the roof to be carried by I-beaina. The construction of
t%. junction of this sort in Philadelphia, may be mentioned as an il-
l\i.stration of the general arrangement* There were two brick aewore, 10
AJifl II ft. in diameter respectively, which came toiajether with inverts
Mt the same elevation. Both were of the brick and rubble typo used
BO €Dtten«ivoly in that cit>\ The total length* of the interior of the
i unction structure wai* 45 ft. The crosa-section^ of the invert were
^wrorked out in the usual manner. Where the i'ide curv^es of the circu-
lar arc of the invert finally became vertical, the walla of the junction
were run up straight and given a thickness of 3 ft, 6 in. The minimum
depth of concrete below the^tone block invert was 12 in. The stot»l
bc&mH re^ng on top of the side waUs, were spaced 3 ft. apart on

^^^ -J'O'

e4 f-Beam^ nr-rr

4 5q, Bar an>unct

\\ii. :i44, — Roof detail, Philadelphia junction*

The longest was 25 ft. and was a 24-in, SO^lb. section. The

;^t wa^ 18 i ft, long and waa an 18-in. 55-lb. section. Fig. 244 is a

fwtail of tlie roof ahowing the construction. Both the form work and

'or a roof of this aort will probably l>e less expensive than with

^v Ix^llmoutlis, but the cost of the steel beams may influence tbe

>-ft of the structure so that it will not be as cheap as one of the

• types* Sections of thia general nature desen^e more attention,

****Wever^ thiin hiw fift«n paid to them, for it is not impossible that by

" structure with a alab top may be develo]jed

, : xiy economical.

1 ^i(sr* are eertain Uieoretical features connected with the deettgn of

'"**• iunftion.i wliich t^hould always be kept in mind, althotigh it is a

*'^wmori nxpcricnce that it is iuipossible to satisfy all theoretical

'*^plretncnts In work of this nature, and the biist the entsiucer can do

tl,

570

AMERICAN SEWERAGE PRACTICE

m to cfTect a compromise which will reeult in a structure of ample strengtk
and fitne8» for the average dcDiands of aervice. These thooretioal

coiiMderations have been auinrned up by Frtihling, as follows:

'* Sewers mtist be j<»iricHl in such a way Ihat nu docrease ui velocity occars^
because that will result in the subsidence ot the silt and suspended matter.
It is as necessATV to avoid, thexeforc, a widening of the channel as the fcintiA-
tion of an obatnirtion to the flow, and the two chAuneLs should gradualljr
blend into each other, but with the elongations and gt tides of ttie itiveits
so arranged that the discharges from the individual brancheg have theaaniA
surface elevation at the point of junctiim. With oirres ponding rising and
falling of t!ie sewage in the sewera which are brought together thiw» it would
be possible to ba»e the dedigns on any proportion of the capacity of the jwe-
tions being ytili»od» hut a« the surface of the sewage in the trunk *ewer tn
ordinarily proportionally higher than that in the Uit<trals» the enidneer ifl
compelled to select arbitrarily some proportion of the full capacity^ as thftl

which will be utilteed, and remem-
ber that an excess luse of the cnpa-
city will cause the additional height
in the trunk sewcr« to back m
sewage in the branches di«'cVi
into it (except those *1
close to its crown), ''i i r

the available difference in elc\'^n-
tions, and hence the (latter the
grades, the lower should he the
proportion of the full cai'
which is choeeti as the biiai^
design, but it must not bel»elow. ii.
proportion whi^^h correipnnd!* t?*
the discharge of the a\'
wciilher sewage, in ord>
backwater may \m Itmitod i<i
periods of flow of the niaxiniuin dry-weather sewage and of the storm wal
With better grades, the de-sign can be ba^ed on larger volumei* of wai
such as the maximum dry-weather discharge or a definite dilution of it 1
storm water; the upper limit corresponds to the rurMjtf of heavy ^tortus,
this case, assuming ihat the sewi^ns nm full, the crowns of the 3*-wer« on* \
be brought to the same elevation but the inverts will be at different eh
tions, corres<ponding to the heights of the different sewers. In
stages, the sewage in the branches will enter the trunk sewer thr
short section having an increased grade.

*'The lengthy /, Fig. 245^ of the junction, depends upon the nutius^ I
and the width, b, of the branch sewer, the increase in widths m, of %\w (
sewer, and the thickneas of the masonry « a, at the junuiton. Tlien

(« - (r -h & + 0.5*)' • (r -f m}»
This shows that a change at the junction lo a section of greutrr width,
from an egg-ahape to a send-ellipticiil ahape» reduoea the tangtli or

Fio. 245.

luncllop. So far aa the value of r is conoerned^ it Is never taken at less than
5h in the better class of designs; the resistance to the flow of the sewage
tficpeiia^ as the radius decreases, but the resulting loss in fall is only slight.'"

Ill large cities the junctions are not always such simple affairs as
ihoee shown iu Figs. 242 and 243, In Fig, 246 a complicated junction
in Philadelphia is illustrated. Here there m a brick sewer 9 ft, in
diamet/er crossing a brick sewer 8 ft. 3 in, in diameter, and the problem
is to put in junction chambers and sanitary sewers in such a way that
the course of the larger sewer, beyond this int-ersection, will serve as a
relief for the storm water from the smaller sewer, and that the dry-
weather sewage in the latter will flow into the channel which will also
corn,' away the dr>*-weather sewage from the former. This was ac-
plished by four junction chambers and two 3(>-iru ciii^it-iron pipe
ers, sho\%Ti in the illustration. It will beobser\^ed that a very large
proportion of the section of the Q-f t. sewer will be utilized before there is
any di«charge from it into the overflow sew^cr, while in the case of the
Si-it. newer everything that is not dry-wTather sewage will be im-
mediately discharged into the overflow outlet.

SIPHONS

r lately there are not two words in the English language to

II up distinction between what we c all inverted siphons, ** Dliker"

m Cfemian, and true siphons, "Hcber/* in German. Consequently

engineers frequently speak of siphons when they mean inverted siphons,

and couwiderable ctmfusion sometimes arises on this account. The

II cc between the two olasscji of structures is as great as that be-

1 the North and the South, however.

Where a conduit has a V-form in its profile between two pointa, that

'^ ' -iW, is provided with a descending and then a rising leg, it forms an

>'d siphon. This may or may not have such a bend that the liquid

JMJttom will always seal the lej^s like a trap. Where there is no

i :^;al, the inverted siphon is commonly spoken of as '^incomplete;"

• complete inverted siphon is really a large trap, duplicating on a great ^

®^*Ic t' : ttus so familiar on a small scale in plumbing.

At: Ml, on the other hand, consists of a rising leg followed by a

-1 leg, the two having an A-form and ser\'ing to raise water above the

- "uUc gnidient between tw^o pKjints on a conduit, by utilizing atmos-

P'^eric pressure. The siphon must discharge at a lower elevation than

t which the liquid »?nters into it, and the maximum theoretical

1 over which the siphon is able to lift water is (32- //) ft., where

« iH i\w head in feet neccssiiry to give the liquid its veloeit>*. If air or

'^ cdllectii at the summft of the siphon, it will eventually interrupt the

*J'*^li^ and on this account various devices are used to guard against thia

*^Rer, It is particularly important in tlie caao of siphona operating

H -

wluch. Table 3 shown, will require a pipe 33 in. m diameter, or two pipes 22
in. in tiiiinietier. It is true that a 22-in. pipe on a 1 : 100 grade haa a nomi-
nal cftpncity of but 17.94 sec-ft., but it will require only a trifling excess
hitmd to Tntik<^ it carry the required quantity* at the wet cross-section of
Niaxiiiiuin discliarge, which is not that of the entire pipe, as is shown in
P*tg. 133. The necessary grade for the maximum discharge will be

20.944* 1 ^ 1_
19.26* 250 ~ 210

AJfiil the excess heiid wiU be 492.1/211 - 1.968 = 0,36 ft.

In discharging 26.486 cu. ft. per second on a grade of 1:300 the 72/48-in»
«**a«-fibafM'd sewer will be filled to a depth of about 2,067 ft., at which eleva-
! i of the relief outlet should be placed ; it is also the datum lor fixing
'*n of the invert of the sew^er at the other end of the inverted
^Apliou. It should be 54/36 in., since at the moment the relief outlet begins
t<i dischaigc this sewer must also be carrying 26.4S6 cu. ft. per second. This
•ill bring the water surface to an elevation of about 1.68 ft, above the invert.
Aa there is a drop of 1.968 ft, according to the original assumption , and one
^ ii.im -f- 0.36) « 2.328 ft,, if two 22-in. pipes are employed, then the
invert of the sewer running from the inverted siphon must be 1,68 + L968
* 8.W8 ft, below the ai!l of the storm overflow, if a 33-in. pipe is used, or
U08 + 2.328 = 4.008 ft. if two 22-in. pipes are used.

Fig, 247, which shows a structure on the sewerage system of Louis-
vfllc, \» introduced to illustrate the manaer in which a bypasa can be
coQslructcU to dL^charge the sewage into a neighboring creek or other
^WHJy of water wheu the inverted siphon requires cleaning. This
^■h^cture includes two 12-in. iron pipes carried under the creek on the
■S^iBtt invert grade as that of the sewer. In addition to these there is
provided n 3(>in, iron pipe dipping down from the grade of the sewer
neneutfi the bottom of the creek. This pipe will act as an inverted
s*F>hon, but will not be put into use until the flow in the sewer exceeds
"*p combined capacity of the two 12-in, pipes. At each end of the
cro«aitig there is a concrete chamber giving access to the siphon to
i^'ilitate cleaning when it is found to be necessary. There is also an
outlet to the creek, through which the scwiige may be
licn the siphon ia being cleaned or repaired. A sluice gate in
^^^^ outlet chamber also makes it possible to shut ofT any backwater from
I be iiitcrcepter at such tiiu»*s. The concrete f>rotection of tlie pipes
fi^ lift top on tlie level of the bottom of the creek.
A l(Higcr structure, jdso on the Louisville sewerage system, is show^n
^^ to Fig. 248. Thiii Ia on the line of a 48-in. sewer and eonsista of vitrified
^K|Kpe oQcafeod in ccmcrete. At the inlet chamber, the arrangements are
I ' ' .^ny one or two or all of the pipes may be put in service,

I lo the quantity of sewage flowing. It wa.s the intention of

I mt to confine the entire flow to the IS-in. pipe so long as the

f aewag'i* did not exceed its capacit>% and then to substitute

■a^tffe

dik

^

^^^^^k .. M^^^^^^^^^^^M

■■

m /

r
i

1

■i

1

1 ^1

I

1

1

1

JUNCTIONS, SIPHONS, BRIDGES, ETC.

576

' the 30-m. pipes. Other changes oan be made from time to time
I to provirle the necessary ixicrease in capacity to meet the growth of
^ity. The entrance to each pipe is controlled by a sluice gate set in
nuHonry and also by stop planks and overflow chambers, so that in
I of emergency the sewage will flow automatically into a second
llird pipe when the one in use is overcharKed. Provision is also made

VfertlcaJ Section.
Fio. 249. — Inlet chamber, Woonsocket inverted siphon,

1 atitnniatic overflow into the neighboring creek ^ and if it is nccee-
thc entire discharge of the sewer may be turned for a short time
I a 3()-in. blow-oJT conduit into the creek. At the outlet chamber,
fw all of 1 can be clo.scd by means of stop planks.

\ tlio lo\^ 1 . of this siphon a third chamber la pro\nded for the

? of draiumg and cleaning any of the pipes. For thi? purpose, the
ia drawn off into a sump and then pumped into the creek,

576

AMERICAN SEWERAGE PRACTICE

after which a section of the pipe 4 ft. long can be removed and th
running from it to either chamber can be cleaned in the anual way..^

There are a nuniber of inverted aiphons in the Woonsocket m'i
system, which was de^signetl by Frank H. Mill8» city engineer, willl|
advice of Dr- Rudolph Herinp;, coni^ulting engineer, A tj^pical i
tare at this place consists of tliree line^ of 12-in, pipe placed 3 Ct,(
c* and embedded in concrete. These pipea were laid across the :
by mean.'! of a coflfer-dara. It will be noticed in Fig. 249, that the ifl
of the 24-in. sewer running into the inlet manhole is about 4 ft. abov^
invert of the cntl of the inverted niphon and in the bottom of the di
is a sump into whicli the bcwagc dropa. Thia sump is separated I
the rest of the manhole by a low dam and weir over wliich Uie aew»g!
flows to the pipes forming the inverted siphon. The weir has a
of thin copper plates. Immediately adjoining this chamber is a '
chamber connecting the 24-in. brick sewer with a 24-in. hy-pas8 to|
river. The sewage is diverted through this by-pass wdien it is d«
to clean out the inverted siphon. There is a retaining wall of gr&niw
rubble laid in cement, at the inlet and the outlet chamber, and in t^io
wall there is a brick arch over the pipe in order that no weight
may come upon the latter and crush them. Another detail to whjfb
attention should be called h the manner in which the underdiaiaj
been sw^ung to one side as it passed under the inlet chamber,
been provided with a small inspection shaft.

There are several river crossings on the sewerage syBtem of Con
Mass., each consi^iting of a line of 12'in. cast-iron pipe. At the hp
two of these there are flushing chambers for accumulating ^cwii^fl
discharging it intermittently in large quantities in order to kocjj
pipe clean. Each chamber is built of brickwork and has a dome]
Fig. 250; one is 2(Kl/2 ft. in diameter and discharges from 15 to 20t
in 24 hours, and the other is lQ-1/2 ft. in dianjeter and discharges 8 to 1
times in 24 hours. The chambers are discharged by means of
Vranken automatic siphons.

There are a number of inverted siphons crossing Pax ton Cre
Harrisburg, Pa., in order to deliver sewage to an interceptcr bull
1903 from the plans of Jamejs H. Fuertes. The connectiomi at both|
of these siphons are shown in Fig. 251, from Eng. Record, Oct. 11, 1
At the inlet end of each, a section of the existing sewer waa taken '
sufficient length to permit the construction of a new manhole,
and connection with a silt baain. The dry-weather »ewage as it '
down the old sewer runs down a east-iron pipe leading from the nu
the sewer invejrt to the siilt basin, which has a depth d» i
conditions encountered at each crossing. ThetwoouU*
are 3-1/2 and 4-12 ft. above its bottom, and the sewage Hows ibi(
them and down under the creek in two lines of caat^lron pipe,

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JVNCTIOKS, SIPHONS, BRIDGES, ETC,

hll

578

AMERICAN SEWERAGE PBACTWS

the other side in a BhalJow manhole, from which it is clIsch&rstHi iaUt il^

intercepter through a caat-iron drop pipe. The sewers ^ ' " on 1
combined 8>^temj and the entrances to the inverted s>i\
signed to permit the greater part of the storm water to pass tlirpdiy
into the creek through the old outlets, flap gates being provided just I
yond the sump to prevent backwater from entering the mterccpt«r i
time« of flood. These gates were made of cypress lumber in order I
eecure lightness, and were faced with rings of steel where they borei
the cast-iron frame. Each gate was hung on two wrought-tron sin^
extending its entire width and sunk into the lower side of it* After
the gate had been hung and closed the face joint was made by
lead into a groove left in the face of the frame for that purpooe.

The sump at the intake end of the inverted siphon, through i
the sewage enters the silt basin, is protect-ed by a cast-iron gratiog.
outlets from the silt basins are provided with cast-iron hoods to jirevfl
floating matters from getting into the inverted siphon, and eluiro i
at the bottom of the basin afford means for cleaning the pipes^J
two pipes under the creek unite at the discharge end in a manholi
which the sew^age flows down a cast-iron pipe into the interoeptGr*

An inverted siphon shaped like a Venturi meter to prevent de|i
of suspended matter by an increase of velocity without approciabte la
of head, has been built on the 39th St, conduit under the lllinoia aod
Michigan Canal in Chicago. The top of the conduit required lowe
10 ft. to permit the necessary 4 ft. 8 in. of water in the canaL
section of the conduit wtis gradually changed from an
14 ft. high and 12 ft. wide, to one on its side, 9 ft. high,
again. The throat section of the siphon is about 65 per crnt. of ^
full section, and it was estimated that the loss of head would he Ici
than OMi ft., while the velo€it>' would be incre^ised to abmit 3 ft. ]
second, which vriis con^-^idered a transporting velocit>' for the :
likely to reach that point . The inverted siphon b 2CK) ft. long, 1
thick and constructed of 1 : 2-1/2 : 5 concrete reinforced witli I j
steel rods forming hcopa 6 in. apart and longitudinal tiea 12 in, ap

A t>Tiical short inverted siphon is shown in Fig. 252. It
the contents of a large drain under the outfjiU sewer at '
has two (j*ft. circular conduits and one 14-in. pipe, all cndii.^ _ li!

in an enlarged chamber. The upstream end contains two grit
separated by a wall rising 2-1/2 ft, above the bottom of t! i < if 1

sewer. Either grit well can be shut from the sewer at th d\

division wall by means of stop planks. The ends of tlie grit w«ll* '
ward the inverted siphons are closed by curvxd dams, tho tops of wh
are 1 ft* below the top of the division wall. The l4-in. eafft-iron ptp«5 'i»\
the center line of the sewer and can be shut off from connf>etio
either grit well by stop pUnks between the division waII and

■iMi

JUNCTIONS, SIPHONS, BRIDGES, ETC.

579

fed dam. The intake of the 14-iE, pipe is 1-1/2 ft, below the
dam and 2—1/2 ft. below the top of the division wall. In

eratiou th(9 pif>u earner the flows, and when these ex-
eity the sewer dischargcji into one of the 6-ft. mphon

580

AMERICAN SEWERAGE PRACTICE

pipes over the dam at the end of one of the grit well:?. Shcmltl I
storm become more severe, tlie l4-m, pipe and both 6-ft- eond«^
will be put ill operation. The normal arrangement is to place i
planki* across one end of one of the ^it wells and hetwreiin thw
well and the opening of the 14-in, pipe* The sewage then flon
Btractedly to the other grit well and into the l4-m. pipe. When
high enough it overtops the dam at the end of the gi'it wcU left
and when it rises a foot liigher overflows the stop planks at tbe 1
of the other grit well and divis^ion wall and discharges through i
the inverted siphom. On account of the custom of swe'^pmg
refuse into the storm-water drains, the structure is required to '
under very trj^ing condHions, but it ha,-^ operated fluccca^fiiUy
its completion.

One of the largest inverted siphons for sewage is used in €aK73rm| •_
low-level intercepting sewer under Wisaahickon Creek in PbilAdelfi
This is illustrated in Fig. 253. The inlet chamber receiver tbi.<
charge from a brick sewer 3 ft, 6 in. in diameter, laid on a \
ft. in 100 ft. The inverted siphon is 152,5 ft, long from the ink
cast-iron pipe to their outlets. There are a 12-, 20- and two
pipes, provided at the inlet end with gates so that only ■
service which it is considered desirable. By using flap g^
design, except for boring holes in some of them in bosses to form c
tions for fire hose, in chamber C and chamber D, a considorable sta
ardization of details has been accomplished.

Siphons.— 'One of the oldest true siphons on a setrerage sj-slcm i
the St. Martin canal in Parb, At tliis place there is a mjiiK>iir]r i
bridge, the Pont Morland, and the siphon is attached to one fact i
forming a semi-circle with a diameter of 52-1/2 ft* It« crown i
more than 26-1/4 ft. above the sewer leading to it. The g&sm '
given off from the sewage ri^e to the top and iire led away t^
riser 49,2 ft. high, from which they are drawn by an ejector worked I
water admitted and shut oS at the right times by a float. The sipll
can be put in operation by means of the ejector in about 5 mb
so that any serious interruption in its service is regarded a* unlikd
French engineers have made teats of this siphon ♦ which havr **hoirD ft
surprwing fact that with a velocity of flow of 3,9 to 4,9 ft* r*"^ '^
the collectiou of gases at the crown no longer takes place.

It is generally believed that the first sewage siphon in tte-
States was constructed at Norfolk, Va., about LSH5. It is a
line 14 in. in diameter, and about ItKX) ft. long* which wa« buiH»]
Engineer VV» T. Brooke to avoid ver>' truubU*somc and
trench work in quicksand. The outlet end is provided with
bend, which prevents tlie siphon from becoming m
summit there is attached a 3-1 /2-in. pipe t h rough w fi

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JUNCTIONS, SIPHONS, BBIDGES, BTC.

581

i arui air are removed by means of an air piinip at the sewage pum|>
ftatioD. Thia tfiphoD wm in satLsfactary operation in 1014, Mr,
Brocikc informed the authors,

TJie best-kaown siphon is probably that constructed at Breslau in

5, to carr>^ the sewage of a population of about 5000 people from an

the Oder to the right bank of that river. It is hung from the

irture of a bridge and is 493,6 ft. long and 5.9 in. in diameter.

"The highed point of the giphon is at the end of the bridge^ and from it

ihi* desceudiug leg drops down into a water seiil in the bottom of a

mnnhole. At the summit there is a chamber in which the gases are

r " 1 As these gatlier, the level of the sewage in the chamber

^ V falls and fhially.it reaches such a point that a float inside the

I ber operates a water-driven ejector, which sucks off the gases and is

*^*iy closed by the rising of the float. This siphon, which was the first

several of the same type in Breslau, although expenaive, proved an

^mical Hubhtitute for an inverted siphon which would have been

expensive on account of local conditions,

\ Extensive use is made of siphons in Potsdam, where one of them has

employed, in fact, a.^ an intercepting sewer. At each point of

jterecption the dr>'-weather sewage is discharged into a chamber, where

it fir*t ik'posHt? any silt or sediment in a sunip, and then passes over a

radl and through a screen into the bottom of the rising leg of a siphon*

\t tlie mouth of this siphon there is a sliding valve operated by a float,

ad somewhat higher in the rising leg there is a ball valve* The float-

vaive clothes the rtiphon whenever there is a chance that the smnp will be

inod completely of sewage, and the ball valve is an assurance again*^t

entrance of air. The gases and air are forced out of the siphon by

watitr injected under pressure into the summit. In order to accomplish

' ' *r the siphon must be closed, which \s done by means of

> mentioned at the inlet end. while at the outlet end,

I iM h is St a pumping ntation, a valve is «hut by the attendant before he

;U the water under pressure into the siphon pipe. The details of

ar-rema\'inK chamber at the summit have been worked out so that

:ire put under a fairly heavy preJ^aure» they lift a heavy

i\^ through small openings into the air. As they ascapo a

^ the liquid which replaces the air. Thia float carries a

:ii ttiu with a needle point at its upper end. When the float has

1 !** ' he maximum position, tliis needle point ent-ers the orifice through

I s escape, and closes it. This plugs up the passage so that

111 ve at the top of the passage fa lb back on its seat. The

9Q(t«nt at the pumping station observes, by means of a pressure gage,

this takes pLirt^, and nhuts down the ma*"hinery which puts the

under pnissure. There arc three point^s where intercepting

itiacbarge into one of these si])homi on the Pott^dam sewerage

582

AMERICAN SEWERAGE PRACTICE

^'V'ii

,'S--|E] Ik

•n^* **

JUNCTIONS, SIPHONS, BRIDGES, ETC.

583

pm. A description is given in FrGkliiig'a ''Entwaaserung der

BRTOGES

The use of bridges in connection with sewers has been fairly infre-
[qnent, partii^uliirly in the United States* The clifficnlty has been the
^tftrung objection to the use of true siphons for such croaaings, and it is

rty possible to support a sewer from a bridge structure unlesa it is

lied up from its position in the street to about the level of the road-
I way of the bridge, which formt^ a siphon. It is possible that with more
experience with siphons the prejudice against them will disappear.

A river crossing on tlio joint outlet sewer in northeastern New Jersey,
' built fram the pl&n^ of Alexander Potter, is shown m Fig. 254, This

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dnek

Bouldtrs in Ctmatte
Upsfrtam and Downstream
from Pi p9

LongJtudinat Section. ^^^^ 5^^^,^^

C.nfGirged.
Fig. 255. — ^Bewer bridge, joint outlet sewer, New Jersey.

*8 *nich an elementary structure that it is hardly possible to speak of it as
* oridgt). The 42-in. caat-iron pipe is supported on posts made of pairs
*>« raiU embedded in concrete piers 4 ft, deep and 7 by 4 ft. in plan,
\ P^^rc is one of these supports for each lengt h of pipe. This construction
' employed in order to minimize the obstruction to the stream flow
«*i.*cure the groate*it possible clearance between support}?. It will
^ obiierv^d that the river chamiel at this place, was widened out con-
\ '^'^^'^bly 80 as to afford a greater waterway. . A more elaborate structure
I ^ the same Bewerage fiy^tem is shown in Fig. 255.
^A r«^nforrcd concrete sewer bridge waa constructed at Morristown,

K.J,

f to carry a 2-ft, sewer across a stream at a jwint at which there

I *• iiot fuilicicnt head available t^ permit the use of an inverted siphon,
md consequently the channel was widened at the
ul the crosi^ing was made in three spans of 33 ft.
iving a clear wklth of 99 ft. without any obstruction other than

584

AMERICAN SEWERAGE PRACTICE

two narrow piers. There was some possibility that the *=itj utime i
be widened and used before long as a highway bridge, and accor
the girders were mudti heavier than would otherwige have* been tht? i
The cro.ss-section of the bridge ha^j a width of 4 ft. and a depth of 3ii
The 2-ft. sewer is in the center. This permits the dosign to be regard
as a pair of girders 12 in. wide and 32 in. deep. I'his br ' .udl

have cost about 20 per cent, less than the bids for astrur
of an iron pipe suspended between steel girders.

A 4-1 /2-ft. sewer is carried across a canal in Denver, Colo*, by i
of a reinforced concrete bridge, 44 ft. long, with a clear span of 40 i
In cross-section it is 4 ft. S in, high and 7 ft. 6 in. wide. The rirtli
4-l/2-'ft. sewer is located so that there is 6 in. of concrete belowj
vitrified brick invert. This gives a cover of about 5 in. aboi
crown of the section, the top of the bridge havmg a transverse i
each way from the center, of about 1 in. The structure is reinfarCT
on each side of the sewer as if both sides were beams, and the 10
dead load of the span is 93 tons. The design was made by H. F- Mp
weather, who considers that a needlessly hea\y and strong stnicf
was built, according to a statement in Engineering Record, Sept, 7, 191!

A reinforced concrete structure of a somewhat lighter i-haracter i
built in Los Angeles in 1907, to carry a 3f>-in. cast-iron pipe sewer
the Los Angeles River. On each side of the pipe ia an IS-in, 55-lh, (
I-beam wTapped thoroughly with 3/16-in. wire surrounded with '
Crete. Every 36 ft.^ these beams rest on a reinforced concrete
iy supported on two reinforced concrete piles* Every 12 ft.
beams are connected by a reinforced concrete diaphragm which for^
a support for the pipe.

A box girder sewer approximately 22 in. wide and 34 in. high wiw c
structed hi 1910 in St. Louis, across a ravine which it was »
fill within a few years, but it would take so much time for
settle thoroughly that it was deemed inadvisalileto delay the eonstmir
of the sewer on that account. The design adopted for tins p
a hollow concrete girder {Eng, Neu% Sept. 5, 191 2) » of two *
with a central pier. The girder was designed to carry tl
concrete, the sewage and a triangle of earth on top of
high* This last provision was to allow for the load wliich mi^
on the sewer when the ravine was being filled and l •'- - - ♦^v
compacted enough to carr>^ the weight of the sewer

FLUSHING DEVICES

The primar>' purpose of fliLshing b to permit
fados which* while producing ade<iuato vol
capacities at the depths assumed in the computationa, m^ noi i

t hi -

K\\

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JUNCTIONS, SIPHONS, BRIDGES, ETC,

585

other deptlig velocities which will carr>^ off at all timc^ M

r. The problem of flushing, strictly speakinjK;^ in usually

55e of keeping lateral sewers clean from their dead eoda to the

where the flow of acwage in great enough t€i accomplish this with-

ce from the water mains. OccasionoUy the problem L* one

g a hirge volume of water to clean out a main sewer or an in-

siphon* In any case, the object is to increase temporarily the

lUc gradient in the sewer by means of an exceptional head of water

Upper end. In some European cities the volume of water stored

ing 13 quite large, bo as to maintain the dbcharge under this ertra

— M<"-^*o- —

1 CoftrhKCffotf

Semdy

Bive Clay :;

Mart and Wdffr

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8% 10^,
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Fig* 257. — Flushing manhole, Minneapolis,

for a considerable period; in the United States the quantity stored
a\\ tank at the end of a Literal 8ewer ia not usually over 350 gaL
^ Crom Brooks. — An example of flushing a large sewer, from a
water course i^ afforded by the intake on the Harbor Brook
in Syracuse, designed by Glenn D. Holmes and sfiown in
I The »ides and bottom of a brook near this sewer wero paved
etc, and provision was made for tern )>or aril n"^ danujiing tlie
5th totop planks. The water thus impounded can he diverted
ru l5-in, vitrified intake pipes surrounded by concrete, into aa
bole. Thin ia bviilt of concrete with a vitrificMl pipe aa the
I being clawd, when not in usc^ with a stop plank of two thick-
-itt- pine, which can be lifted out of the bull by a cliain when

i^iii

586

AMERICAN SEWERAGE PRACTFCE

flushing 18 to begin. From the bottom of this manhole a 24*in. vitrififti
pipe runs directly into the 33-in. circular concrete intercepting newer,
A manhole ia located a few feet farther up the line of the sewer. The
difference in elevation between t he top of the temporary atop planks m
the creek and the invert of the iotercepter is about 8 ft.

A flushing manhole built on the Minneapolis sewerage system,
1895, from the dasigns of Carl ILstrup, is shown in Fig. 257, from Eng,
Record^ March 28, 1896. This manhole was constructed where a Urge
brick sewer crosses a swamp and in so doing runs through a creek. The
ground was very soft and troublesome, and piles were driven on which a
grillage was laid below the lowest water level, affording an opportunity
to build the sewer inside a coffer. Stone walls were first laid and after-
ward a mass of concrete was placed between them, of sufficient volume to
give the necessary weight for such a structure. At one side of the sewer,
the excavation was extended sufiiGiently to deepen the bed of the creek
into a shallow w^ell, which was roughly walled and paved so as to bring
its bottom about on a level with the springing line of the brick arch of the
sewer. The manhole built up on this foundation had a 2-ft. opcoinl
into the sewer, which coidd be closed tightly by a sliding door. On \ he
opposite side of the manhole was an opening into the creek guarded W
iron bars to keep out rubbish. In this way the manhole w^as kept full <^
water up to the level of the surface of the creek, and whenever r
desired to flush the sewer the sHding gate between the manh(:le aa
sewer could be opened, admitting creek water in this way under a so****
head. j,

A flushing chamber was built at the end of an intercepter constni*^*^
in Harrisburg, Pa., b 1903, from the plana of James H. Fuertes, ^
worked satisfactorily for a considerable time, but was finally prartici^**^
dispensed with, owing to t!ie admission of brook water at a manha*^
short distance below tlie headworks. It was necessar>'' to use very fl^
grades in order to avoid prohibitive excavation and pumping, and t-l^**
grade difficulty was overcome by making the sewer somewhat lar^
than necessary for the interception of the dry weather sewage alo^^
and by forming a cotmeetion between the upper eiid of the sewer i*^
the neighboring cre^k, where automatic regulating gates admitted dut'i*'*
dry weather enough creek water into the conduit to keep the flow in '■***
its parta at a self-flushing velocity. During storms, when the
sewers were discharging large quantities of both sewage and street w^'
into the intercepter, a float rose which closed the valve and shut out * ***
creek water.

The design of the chamber is shown in Fig. 258, Two seta nf thrrf
12-in. vitrifieil pipes ejctend through the concrete head- wall na inlets *^
the creek water, one set 4 ft. higher than the other* Tli<
through a large silt basin in order to become free from h* . '^'

JUNCTIONS, SIPHONS, BRIDGES, ETC,

587

ad then paaaes through rectangular cast iron orifices into the
; chamber proper. The valve regulating the admission of the
Water is of the usual type, the opening being auloniitticjilly con-
a galvanized iron float. The rotating arm la aUacluHl tt> the
vail of the float well by a short length of angle iron, the hole
it i^ bolted to the latter being slotted so as to permit a
tment. The horizontal leg of this angle and the flangea

aion carrying the rotating arm are slotted to allow a hori-

in two directions. When the valve was installed it waa

iti place, atijusted by means of the slotted holea until it

rrfertiy, and then bolted to its final position.

^at well waa connected to the sewer by a 4-in. vitrifietl pipe

slow the invert about 10 ft. down the sewer, where the

i covered by a cast-iron grating cemented bto the bell of the

part* of the vnlvc with its rotating arm and lever were of

588

AMERICAN SEWERAGE PRACTICE

cast iron except the face of the valve and all weariug part^ which wot
bronze. The galvanisjed iron float was 11 X 24 in. and 9 in, difyi
With the exception of the brick manhole the entire constnietioo wbi cC
1 :2 J ;4J concrete reinforced by 3-in. No. 10 expanded metal.

In Europe sewers are occasionally flushed by means of the sevap
itself. To accomplish this, flushing clmmbefs which rontato Isifi
gates are employed. These gates are usually open, but are clofirf
when flushing is to be undertaken. After they are closi^d the senrifi
backs up behind them and when a sufficient quantity has boeaj
it is suddenly released by opening the gates, which is iicconiplc
variety of ways. Apparatus of this nature has rarely been
in the United States. Other methods of keeping the aewen^
generally preferred and are described in Volume II.

Flushing Manholes. — The flushing of small sewers is carried o& dthcf
by hand or wil h the hdp of automatic apparatus. Opinion see au» to W
di\'ided regarding the merits of the two methods; the authoirt' vw
are stated in Volume II, under the operation of sewerage sj-stctniL A*»
general proposition all flutih tanks require some mainlenanco, and \)m
cost is therefore dependent, in a metisure, upon the time spent m b-
specting and repairing them. The cost of this time, plu.i I he iiitenst
and depreciation on the investment in the apparatus, : * ' '

the water used for the flushing, must be offset against t
and w^atcr where hand-flushing is employed, for the dififerencc in
coat of the manholes used in the two cases is negligible, T^^ •"
of water to be used for flushing and the frequency of the i :
pend not only upon the grade of the sewer to be kept cloaa^ bu; j
upon the poasibiUty of dirt finding its way into the sewer.

Hand-flushing is generally done by means of a hose from the i
fire hydrant^ inserted into the manhole at the end of the latend or imX
summit of the sewer to be cleaned, flushing nmnbolci!; are also wed
to a con^jiderable extent. In this case a 1- or 1 J/2*in. bratidi fPM
the nearest water main is run into the manhole and the cnf-u-. r!v
the sewer can be closed mth a flap or tripping valve. Water i^
the manhole through the service pipe, and when it is ful! '
is tripped, allowing the water to rush into the sewer. The y:r
accomplished in some places where valve^s are not used^ b'
the end of the scwcr with a disk consisting of sheet rubber f.iv
canvas and held firmly between boards about 1 /2 in. smaller th
diameter of the sewer. When the tank is filled with water tlus piyj
is drawn out, thus starting the flush.

Automatic Flush*tanks» — The flushing done with autom*
paratus is generally much more frequent than where hanr! '1"
practiced^ the usual rule being to discharge the flush-tiuik
24 hours. The wajer ia usually admitted to tlieso t^mka throti^t i

JUNCTIONS, SfRHONS, BRIDGES, ETC.

589

krificca, of which a viiriety are maniifacture^ by the inakens of flunhittg
■phoDs^ 8o that any desired rate of flow under any street main prejteure
lie attainoci by s^'rewir»|? the proper orifice or jet into the end of the
Dr\'ico l>i|«e. As a nilo these jet^ arc alno acconipanie<l by a mud drum

re^uiug device and a bUiw-oiT cock, provided to iiwure the jet against

lie of>oratioii of a Kiphon of the simplest lype is an follows: In
fig, 2h9a, the Miller sijihon is shown just ready to diacharge. There
fe two volume^ of water separated by the comprc88od air in the long

590

AMERICAN SEWERAGE PRACTICE

leg V of the trap. As the pressure on every part of this confined mm
of air must be equal to the hydrostalic presaure, and as there are
but two places where water is in contact with the air, it follows that the'
depth of water C in the tank must be the same as the depth // ijj the
trap. When the depth C is increased the water flows over the rawed
lip of the trap at D, this discharge allowing a little air tu escape Mow
the bend at B, The air pressure being released in this way, water pnsiefl
up with a rush within the bell and into the long leg of the trap.

The elevation of the lip of the short leg at D above the bottom of th^
outlet is an imporiuiit detail, as upon it the first sudden discharge of
the trap seems to depend. In the older types of flushing apparatoit this
first strong flush was accomplished by using an auxiliary siphon at the
bottom of the trap casting, a detail retained in the Rhoads-Miller siphon,
Fig. 2o0f/, for use where shallow construe t ion is imperative.

When the water in the tank has been drawn down until its surfac-e is
below the snift hole *S, air rushes into the bell and stops the siphoiii''
action there. In consequence the water in the two legs of the trap at
once forms a seal there and the apparatus is ready for discharge wh<^n
the tank is filled again.

The dimensions of the Miller apparatus, rc?quired by designers, ^
given in Tables 161, 162, and 163. The diameter of the tatik ia the
minimum which is generally considered desirable for siphons of ^^
sizes listed. The discharge is the average given by the makers for t^^*^
size and setting of siphon.

The setting shown in Fig. 259a does not afford access to the sewef » '**
the late Andrew Rosewater devised the special design shown in ^*^*
259c to overcome thl*^ defect. The manhole at the dead end of the se^^'^
is provided with a flush tank and siphon^ and while this is more
than the standard type, it not only affords an opportunity ii
cleaning rod into the end of the sewer, but is also stated to give a lii^ *^^
rate of discharge. .

The same object, affording access to the end of the sewor la attai ^^
by placing the trap at right angles to the line of the sewer, instrad m
the same Une* This was first suggested by William Mackintosh*
locating the bell of the siphon at one side of the line of the sewer^
latter can be made to end in a special casting which not only receive*
flush from the trap in the usual way but gives access to the sewer thro "^^
a removalile cover. This design, like the other MiUer t>*pes, is mud
the Pacilic Flush Tank Co., and the sizes of manholes and dimen*
and capacities of the siphons are the same B3 given in Tabic It>l
standard settings.

In the operation of these tievices, the air needed to lock the tij>p#r*»^w'
during the filling of the tank enters the bell through a
enough air is not admitted^ the water may dt-i^'i' M»ir-

By

the

JUNCTIONS, SIPHONS, BRIDOBS, BTC.

591

i

O
2

m

OQ

as

I

o
m

04

o

00
H

<

o

0

H

a
Q
I

5

^ lo CO 00

Riaeto

overflow.

in.

Z

eo N w w

Floor
depth, in.

F

^ lO CO CO

>x

SS3IS

|«j

ss;^^

4

J]

CO CO ^ ^

00 oa »-< CO

^-1 1-H

^1-

Tr«p
depth, in.

J

.4« «•)« Mia *4n

a 'S ,4« •>•• HM

^1 o 3 2S&

c

1

i

>4« mm Hn HN

|f

3
o

<6 d ^ ci

13

1

« 00 o »2

'^ » X c^

to CO

w w

tf.9

Hi
uTi
s*i
oi
»ri

si

lo 00

CO '^

t^ 00

;:2

28

mtm Hn

S8

d 6

ooe

<o 00

d

o

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OQ

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s:.s

^ IQ CO 00

i»i
«:i

^ S w S

CO CO "^ WD

oi
%i

00 O W WD

1-H l-< ^H

WD CO CO t^

*"i
4ci

sisf

CO CO '«*< WD

K'i

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1-H r^

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w4^ Mt* wttm mm

if il

.4« MHD .Hn >««

2288

d '-<' -<' ci
■«"o(ro""u5

CO ,4« MHD .^ >««

s

592

AMERICAN SEWERAGE PRACTICE

the apparatus, instead of flushing at intervals. In some of the siphow
made by Merritt <k Co,, the air is introduced by a Moise reguhitor, Fin.
260, It has the dual purpose of admitting air under the bell and ot
filling the tank with water. This is accomplished by injector action ;
the water from the service pipe, after passing through a mud dnm
passes from a nozzle across a short air gap into an orifice at the end of th?
pipe leading to the bell of the siphon. Tliia jump through the ak i»
relied upon to entrain enough air for the operation of the ap}
The water escapes under the bell into the tank. This cotnpnn}
facturea several types of flush-tanks.

A standard flash-tank was di
signed in Winnipeg undrr the
direction of Coh IL N. Ruttaii,
City Eng., wliich is vented by a
pipe as shown in Fig, 261. Thif
is one of the simplest for- -'
such apparatus. An i:
different type of flush-tank i? ii«<
Van Wanken, Fig. 202, the illui-
tration showing the stnicti
built in Concord, Maafi,
sewer to be flushed ends in *
well in the floor of the i^k,
which has a water-tight nwUl
cover. A S-iu. siphon ha* i^
long leg carried down t^
the plate. The bottom
leg is trapped in a tilung tf»y
which is so balanced that wl
nearly full its center of gravity is brought forweird tind it tilta dol
allowing a part of its contents to flow out. This changes sudd<^
the air pressure in the siphon and starts the apparatus in action*

Value of Flushing* — The only theoretical analysis of fluahin^
which the authors are acquainted w;ls presented by Ajsa K. Ph
superinteiulent of the sewer department of the District of Cohuabia> 1^
a paper i>efore the American Society for Testing Materials in 1 S9S. Th*
paper gives the results of many measurement** of the extent of fltahiol
action in pipe sewers, and pr^cnts the fallowing gencml diifcuaeiafi ^
the subject:

*'The ohjcct of the flush is to seeure a periodic velocity *'* uM.tv iii«a '
ft* per second ui the up|x^r portion of the ^ewer and to ttniintaiti lliv «
to a point whure the urdinary flow attains this ritte. P
amount of normal flow in the aewcr, it in cviiirnt timt the ,
lo aatiafy thin condition im n function of tlie diameter of thv; ^i»<;i

IB

Fio. 200, — Moiae wtttt*r regulator »

594

AMERICAN SEWEHAGE PRACTICE

itfi gradient. From the general considcrfttloti uf the well-knowii fa
for velocity, V^ - C^/R8, remenibering t hat for circular conduits the hydmull
radius is u direct function of the diametert we may consider (1) the quantity
Q varies liifectly as the square root of the radius and inversely as the; Mjuftj
root of the slope, and, to complete the st4itement of controlling conditinw
(2) that it varies directly aa the leni^th from the dead end to the point wb
the normal 6ow becomes sufficient tu maintain a velocity of 2-1/2 ft.
second. Under these ajssiimed conditions^ designating this distance by 1
letting c represent the necessary modifying coefficient, the formula wo
take the shape^ Q = L^/R -s- <r\/5-

"Solving this ecjuation for the data given on the Park Street line
in the opening of the paper) we obtain a rough approximate for c of 19

" Let UB now consider the factors which establish the value of L. If ^

^^'ffgs^f^

l^-^^^-gj^^;^;*!;^; ^^j^'^^-l^^y

Section C-D. Section A-B.

FiQ, 2a2. — Van Vranken flush-tank.

let A represent the area of the cross-section of normal flow for any gW
gradient required to produce the velocity of 2-1/2 ft. per second ^ and I
D equal the increment in discharge for each linear foot of sewer in cuhte I
per second^ then L = 2,5A -^ D^ m which A is definitely determiited 1
an application of Kutter' s formula. The quantity D is evidently a fund
of the number of persons or premises tributary to the sewer and of their |
diem water consumption. But the,*^ are variable quantities, rarely the sa
for two sewers. A uniform contributing population of ^0 pcrsofis per
ft. of sewer with a daily flow per capita of 100 gal., three-fourths ai»u
to run off in 6 hours, would give a value for D of 0.00015 eu. ft. per sin**!]
Table 164 gives the value of A for different grades^ and the corr«7ap<md
depth of flow in inches. This table indicates the very small floir oo
larger grades necessary to maintain a self -clean sing velocity^ and itie
tion between the ordinary discharge and the grade within the limita p^

*' Table 165 gives the various quantities of water givrn by ih© 1
for the foregoing gradea and sixes under the conditions which ItAll

■ JUNCTIONS, SIPHONS, BRIDGES, ETC. 595 ^^H

^■rtng an increased rate on long lines and a diminiAhing rate of flow ^^^H

^^Bes form the average value of 0.00(^>i5 cii. ft. per second. ^^^^|

^Besulls indicate that a very conBidcrabk modification of the ^^^^|

^kter should be allowed for line8 of different gradient, and that ^^^H

IRi volume diminishes verj^ rapidly with an increase of grade; ^^^^|

i it is affectyed to a smaller extent by the size of the acwer, that for all ^^^H

flush-tan k« arc probably required on slopes exceding 2 per cent., ^^^^|

lay be inferred in such cases, also, tjiat flushing at. lead freqtient ^^^^|

■Reeded than the 24- to 48-hour discharge. ^^^H

vK' — SEcrnoxs in Sqttark Feet and Depths in Inches to Produce ^^^^M

k Vklocitt of 21 Feet in Set*t5R8 6 to 12 In. in Diameter ^^^^|

AND OX Grades of 0.5 to 5 Per Cent.

^^H

w

Dim meter af am wen

H

6 in. 1 Sin. 1 10 in. I 12 In,

w.

0.229

0.226

0,237

rth

5,0
0.130

4.3
0.137

4 1

0.150

^H

r<

0.125

itii

3.9

3/2

3.0

2,9

^^^H

»..

0.095

0,101 1 0.108

0.115

^^^H

Jth

2-9

2.7 2.5

2.4

^^^H

.

0 043

0.050

0.55

0.060

^^^H

.th

17

1,6

K6

1.6

^^^H

a.-

oa-u

0.0v^5

o.aj7

0,041

^^^H

itV,

13

1.3

1.2

1.2

^^^H

0.022

0 025

0.028

0.031

^^^H

^^^^. .

10

1.0

1.0

1.0

^^^H

^^B*

0 017

0.021

0.024

0.027

^^^H

yth

0 9

0 9

0.9

0.9

^^^H

Tablic 16'>. ^Gallons of Water Required for Flusihng

^H

■r

Ditt meter of sawerB

■

8 in. 1 10 in. 1 13 in.

■

80

90

100

■

55

65

80

^^^H

■

45

55

70

^^^H

■

20

30

35

^^^H

■

15

20

24

^^^H

^

10

' 15

20

^^^H

s

8

10

15

^^^1

^■tigation of the action of water in flushing sewers was made

^H

K N. Ogdcn at Ithaca, N. Y., about 1S!)8, and the results are ^^H

^■y him in a paper in Trans. Am. Soe, C. E., vol. xt, page 1. ^^^|

J«.iR«tion was beRuii to determinn the necessity of a flush-tank ^^^H

ead of every litterul sewer iti that city, in accordance with a ^^^H

^■fttion made by the designer of the system. Professor ^^^H

^Krapondencc with other engineers showed a wide diversity of ^^^H

596

AMERICAN SEWERAGE FRACTICM

opinion^ some preferring hand flushing, others automatic ftixaliiikg, i
still others combinations of the two. A few had taken up hand fitsthni
because of disastrous experience with automatic apparatus^ and k few
had adopted flush tanks because they found it impntrticaijlc to «hti
good hand flushing.* Little practical iriforniation was api
tained, although one engineer reported that experience or
system under his charge indicated that one flush daily on a 2 per (
grade was as effective as two flushes daily on a 0.5 per c
flush being of 300 gal. The general opinion was that ^
ing was needed on the upper ends of all laterals on grades beluw 1 j
cent.

Professor Ogden*s experiments were made on 8-in, pipe sewers, vatk
with a 4-ft, manhole at its upper end. The end of thr si^wrr
stopped with a pine boarrl having a 5- in. orifice, closed by a rubber-fai
cover. The manhole was filled with water to dei>tha uf 4 to 6 ft. and
when the cover was removed the water was discharged at rates of I
to LI sec.-ft. The depth of this discharge and its effect in no
gravel were observed at successive manholes down the sewer, Fliwf
of 20, 30, 40, 50 and GO cu. ft* were used successively.

As a result of these investigations Professor Ogden reiichrd tbf toik-
elusion that the volume of water discharged should not be loss than 40
cu. ft.^ and the effect of the flush can hardly be exj>ected to reach ujoit
than 60O or 800 ft. If tanks are used on grades greater t han I per
15 to 20 cu. ft. give as good results as larger aniouuts, but on
grades hand-flushing will be more economical than automatic fiushio

In inquiries concerning the capacity of flush-tanks a defini
received only from the Van Vranken Flush-Tank Co,, whicb
the capacity of the tank sfiould be equal to half that of :*
in which the grade produces a rise equal to the diamti
It was the opinion of the manager of the Pacific Flush-Tnitk Co* tta*!
flush of 175 gal, on a 1 per cent, grade was sufficient, and on ttttn
grades twice that quantity of water should be used.

In the discussion of this paper^ George VV. TilLson stated that
Omaha on G-in. lateral sewers with grades of l/2 to 8 per cent* and I
flush-tanks, a growth of fungus half filled the bore of the later&U in 1
course of a year or two. In later work of the same sort, flu
discharRing every 12 hours were used at the dead endw u( the !
and no trouble from the fungus was observed in such cases.

» GcorfCD ft. Kftfl. 4uperifit*»ndent of t he Kew Orle^nf S«» ftor«*i ftfi<^ ^^ ^v Mfi;^. laltftttairf

the ftuthors in 1013 thnt while thertr arv automotir 0ush-tuoW# au n <
in that city, thvy »rc not operated conBtutjUy. *'luoU?itdf «« t4 -
enine ovpr the «yBt4^>ni. cu\**rinK ulJ tlnnh'ttiukA nbout twiot* n mouUi
fiv© fluKhca in mpid ftueceission jiiBt ii«iiv»i on « I4n. pipe and nmtit vali
to tH« flusJi'tank. ftnti fill thrm. ThU ttiiiki'ii wMvti follow ivnv** dnwr*
think Mves wAier <inH gvia tuettcr cflpcl in t|ii«<hin£ unH rrii>olirMi fkirthvf '
with oil effective lluati tb«in two or thrco 4iuU»ma()«' <lisehttrftt*« per ti^y t^nx
lo thii wt kiwp twu Kungs going o^'vr nil Mwera cunatAntly with bull luid dluli

4

CHAPTER XVI

ItEGULATORS, OVERFLOWS, OUTLETS, TIDE GATES AND
VENTILATION

The function of a sewage flow regulator is to prevent the surcharge
an intercepting sewer, by closing an automatic gate upon the branch
^er connection, thus cutting off the sewage and forcing it to flow to
lother outfall.

A storm overflow is designed to allow the excess sewage above a
i&nite quantity to escape from the sewer in which it is flowing through
1 opening.

-Tt/t'fale Pipe
Section A-B.
Fig. 263. — Old type of Boston regulator.

The purpose of both devices is substantially the same, namely, to
low the ordinary flow of sewage to be delivered to a distant point of
ischarge, and at the same time to cause the excess storm flow, which

very much less foul, to be discharged into the nearest watercourse.
ometimes regulators are used in combination with storm overflows to
^eguard an intercepting sewer by cutting off entirely the sewage enter-
Dg the intercepter when the latter is filled to a certain point. The

697

598

AMERICAN SEWER AOE PRACTICE

overflow allows the escape of excess storm flow; the regulator fin
causes the entire flow in the branch sewer, both sewage and storm wat^
to pass the overflow and be discharged into the nearest waterco

REGULATORS

A discharge regulator usually consists of an automat ir g»
operated by a float which rises or falls as the elevation of tlie sewai

Sectional Plan.
0

^«*=^^<*"^-C., Section B-B.

Fio* 264. — New typo of Boston regulator.

increases or decreases. When the intorcepter is lilierl
the gate closet* entu-ely and further diaclmr^ge "*
intercepter Is cut off.

WLATORS, OVERFLOWS, TIDE GATES, ETC.

599

\W

I

C

\ 1

-J.C'

V

> < — .?*<

o

c

^IHF

I

0
s

4

g

eg

^*»

a

I

o

'i

s

6

600 AMERICAN SEWERAGE, PRACTICE

Probably the best-known type of regulator is shown in Fig. 263;
this is used on the connections between the Boston main sewers and the
Metropolitan, intercepting sewers. The structure consists, in brief, of
an orifice in the trunk sewer, a pipe connecting this orifice with the
intercepting sewer, a regulating gate, a float to operate the gate auto-
matically, and a telltale pipe through which the height of sewage in
the intercepting sewer is communicated to the float chamber.

The orifice in the trunk sewer is designed of suflBcient capacity to
allow the proper quantity of sewage to pass through it. In some cases
it is necessary to provide a low dam in the trunk sewer at a point im-
mediately below the orifice to assist in diverting the sewage. The pipe
leading from the orifice may pass through the regulating chamber and
thence to the intercepting sewer. The regulating gate seats against
a cast-iron nozzle which forms the orifice in the tnmk sewer. This gate
is carried on the end of a lever, to the other end of which is attached a

Wiight^

Fig. 266.— Coffin regulator.

large float which rises and falls in the float chamber with the rise ^-^
fall of sewage in the intercepting sewer, the communication of ^^
height of sewage between the intercepting sewer and the float chan^^
being accomplished by means of a telltale pipe of small size which cr ^^
nects the two. Thus as the depth of sewage in the intercepting se ^"^^^
increuiscs in time of storm, the float is raised and correspondingly ^
gate is lowered or closed. When the intorcepter is as nearly ful - " '
desired, the gate through which the sewage flows is closed, thus '^^lliy^
venting the flow of more sewage into the intcrcepter, and at the si=^^^
time causing the sewage and storm water to flow past the orifice thrc^^"^
the lower part of the original trunk sewer into the river.

The experience with the mechanical features of these regulatora^i^ ^^
been satisfactory except in one resi)ect. There has been a tend- ^nC?
in some im?tallations toward the formation of deposits around the ce:^tra/

REGULATORS, OVERFLOWS, TIDE GATES, ETC. 601

at ehnmber, and to avoitl tlji» a later arrangenieDt, Fig. 264, was de-

loped by C. H. Dodd under the direction of E, B. Dorr, chief eDgineer

the Boston Sewer Service. The top^gle joint gives a leverage of about

: 1 when the valve closes, which is a help in reducing leakage. Only

c fioat is needed for the regulators on 8 and 12-in. sewers.

Where it is desired to intercept only a constant volume of sewage,

ourse may he had to a constant-flow regulator, of the t3^pe shown in

rig. 265. The depth of the sewage over the entrance to the vertical

leseopie outlet pipe \b maintained constant by lifting or lowering the

pe as the level of the sewage fluctuates. This motion is produced by

e two large brass floats attached to the top of the pipe.

The simplest type of regulator is sliown in Fig, 266, and is made by

e Coflin Valve Co., of Boston. It has a cast-iron body which is bolted

the end of the branch sewer and projects into the intercepting sewer

a tank connected with it in which the sewage will rise to the same

ight as in the intercepter. The valve and frame are fitted with com-

isition facings, hammered into dove-tailed grooves arid pinned. The

v^e and its seat are machined and then scraped b^^ hand to give a

a*sonably tight circumferential bearing. The stec4 shaft carries an

us table cupper float and a weight by which the action of the device

« be somewhat varied, This regulator is also employed as a back-

ater valve to prevent sewage backing into branches from a main

wer that becomes surcharged.

Other types of regulators used at Syracuse, N. Y., are shown in Figs.
»7 and 26H, which require no comment. There is a limit, of course^
ond which it is hardly wise to expect such apparatus to operate auto-
tic ally, and it is not surprising that one of these regulating valves
to work according to the chief engineer and designer nf the
tercepting sewerage system, Glenn D. Holmes, after it luid become
logged with a 2 X 10-in. plank 5 ft, long, a roOer 6 in, in diameter and
ft. long used in moving buildings, a 2-ft, length of a similar roller, a
8-in. timber 4 ft. long, mop and handle, broken crockery, rags and
sticks. How such collections of large objects get into the sewers
the first place and are gathered at one sput after entering them, is one
the questions which occasionally puzzles the superintendent of any
;e sewerage system.
t>'pe of regulator is used at Washington, D. C, in which the floats
e operated by clean water from the city mains, admitted to the float
ambers through valves controlled by the rise and fall of sewage back
an overfall dam, Asa E, Phillips, superintendent of sewers, stated in
913 that the most elaborate installation, shown in Figs. 269 and 270,
ad then worked with absolute regularity for 2 years. It is so well
balanced that it delivers the sewage from the trimk sewer into the $-ft,
liercepter so long aa the latter is not filled. As soon as the full capacity

602

AMERICAN SEWERAGE PRACTICE

2

c
o

c
o

s:

c

0

^

f

OQ

REGULATORS, OVERJ^LOWS, TIDE GATES, ETC.

603

f the inlercepter is being utilized, the reg:ulator cuts off the flow to the
^tcrcepter, and as soon as the latter is able to receive more sewage, the
ilfltor starts the fiow again. The following description of ita opera-
on is from Eu^. Record^ vol. Ixv, p. 312.

*'The apparatus for controlling the quBntity of storm flow delivered to
be 3-ft. intereepter, and for cutting out excessive storms, is locut^'d in an
adergrouDd concrete gate chamber built just off the main line, and con-

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Fio. 2(i8» — Regulator Uised at Syracuse, N. Y

thereto by a 3-ft. conduit. Above this connection the trunk st^wer
I trunsformcd in section from a circuhir to a cunett^ section, thus ft^rming
[collecting channel for the diversion of the flow to the gat^i* t'hamber. Thia
anettr extends as a tongue below the 3-ft. outlet conduit for the purpose of
Averting from the intercepter the heavy mat4?rial such as cobble and
uider, wtiif'h excessive storms bring down from raw surface areas 'within
drainage district. Just where this tongue of the cunette dies cut in

604

AAfERICAN SEWERAGE PRACTICE

the berme, a slight ridgc is raised, farming a low croes dam for the porptm
of holding the hydratilic gradient at surh a level that the 3-fl. interftpiv
will run full hi*fore any discharge is spilled into the stream.

*'The automatic regulating appuratua is designed t-o entirely
flow from the intercepting sewer Just as soon us the Litter is ru;...~
Under this condition the flow Ln the trunk sewer is about level mtli |
of the diverting weir. This result is acconiphahed by moans of lurikl
with disks IB the form of eyUndrical surfaces, whicli slide upon bronic«irmtB
in eastings imbedded in a concrete bulkhead wall across the line of %m
From these disks anns project with floating balls <A copper on the (fid*44
same anrl working in a pair of concrete tanks, so that by auton
filling and emptying the tanks at the proper time the balls arc madoj
and fall and to dose and open the valves.

xmtnpm

so'

cm

inK

,,111?

Flifthiftg Bemrt -*^

Fig. 269. — Plan of regulating works, Piney creek sewer, Wi

"At the proper level below the diverting dam in the main «rwi-^ h» ^fti
the required discharge, as checked by experiment in the shop, a
is introduced and leads to a pair of outlets in the regulating rhattuwr,
one directly over a small funrit'l pail, hung from a lever arm in suckf
that a downward movement of the funnel lifts a ball vaivt
outlet from a lO-ft. capacity reservoir suspended from thr r
chamber, which is filled through a float-controlled
tion with the city watvr main. This 2-in, pipe dib^ *^

float tank below on the floor of the gate chamber^ and raises the iargr •OJO''^
float which closes the automatic gate.

**\Vhen the flow in the main sewer rises above the inlet pipe

the level of the diverting weir, water passes into the two su^t-

flUing thcin and thereby causing suflicient weight on the n

arm to lift the ball valve on the o\itlet from th*? ri!servH>irt wbi

to the float tank. The water rapidly rises in the latter, Uli

flrmt and ^rudually closing the segmental slide-valve in the LiiiLhc-*d '

Ttiis shuts off the flow of sewage into the 3-ft. interceptor and autooial

r"

I

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n.

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A nolf79i

VLATORS, OVERFLOWS, TIDE GATES, ETC, 605

to Piney Branch. Peak load of the stonii ia thus entirely
B the stream. But as soon as the run-off ta sufficiently re-
trolling gales open and the flow is once again diverted to the
wer. The operation is as foUowa;

flow in the main sewer drops to the capacity of the 3-ft. di-
pter it ia just level with the inlet to the small pipes te^dini;
, so that the flow which has kept the latter full is reduced
ihargo capacity of (he funnel outlets, and the writer therein

awAy, rcKlucing the pull on the lever arm from which they
I and thereby causing a counterweight on the extension of
»e the ball valve feeding the float tank,
i tanks arts drained by small outlet holes and when the feed

cut off they slowly empty and the floats descend, gradually
ling valves, and delivering tlio discharge to the 3-ft. intercepter-
I continues until the next exce.ssive storm dii^charge. Mean-
^oirs over the float tanks have failed from the city water supply^
for the next storm,
^ period when gates are closed, the city water continues to

reservoirs, and thence into the float tanks^ thus keeping
bich hold the controlling gates shut, notwithstanding the small
lich are always open and continue during this period to wa«te,
lourse, being set to exceed this outflow. This is accomplished
k^nply pipe. The feed pipe leading from the main sewer
HpiTit^'cted by a screen and so connected and valved in the
Ihat the city water pressure may be turned througli same for
kt pipe and cleaning the j^creens. This conncetion also server*
tmg out of the apparatus at any time. Immediately after

practice to hav^e an inspector visit the works to examine same
iai flushing necessary."

of installation in Washington is shown in Fig. 271.
I are for the purpoe^e of shutting off the intercepting sewer
thifl place, when this becomes nece88ar>% and diverting the
the Mi. sewer heading to the pmnping station over the
t outlet^ or into a bypass, leading to a 6-fi. storm-water
I miming to the Potomac river. Below the elevation at
h^iatTDg structure operates all storm water has to be
ihis is the lowest place from wlurh there is a gravity di»-
I ret^uJators arc operated by the same kind of apparatus

Eonnectioa with the first Washington instaUation. In
13, Mr. Phillips wrote to the authors as follows: "We
tor chambers of this general character at present in the
line half doxen additional planned for construction. All
have given mod; satisfactory result*^ with the flt)!itrtank
lOted above. We have never attempted the hazardous
ing the float directly in the sewer to be actuated by
the aewttge flow itself/'

608

AMERICAN SEWERAGE PRACTICE

In Rochester, N. Y.^ where sewers are built in tunnels a.*^ i^

Fig. 272, City EnKineer E, A. Fisher has adapted the t>'pe ot -r 1

shown in that illustration. This has unusually sturdy members in
proportion to the 12 X 20 in. opening which is under control, and ia also
untiaual in that the disk is not designed to be able to shut off the dis-
charge openinc; completely. This closing can be accomplished by ban
however. The operation of this regulator is described as foUo^^ in llj
report (1903) of Mr* Fisher on the sewage disposal system of Roche

*'It is contemplated taking into the intercepting sewer all of the sewt
and two and one-half additional volumejs in time of storm. The stomi wa*i
in the outlet sewers in excess of this quantity will pass on and diaeharge in
the river, the existing sewers thus becoming o%'erflows beyond the pomt)|
interception. In order to control the flow to be diverted into the intercept
chambers will be constructed in which regulating devices will be inetRll
that will automatically maintHin the rcqiiirtHi volume of discharge, Thu
regulating devices will he operated by a float, located in a chamber in whi
the water will rise and fjill as the volume entering the chamber is in (
of, or leas than, the vrrlunie discharging. As the water rises the
operate a shutter closing the inlet, thereby reducing the volumefCli
until it is equal to the volume discharging; or if it grows less than the 'volti
discharging, the water in the chamber will naturally fall, thereby cat:
the float to again open the shutter. The discharge from the chaiubfir^
fixed by the size of the opening and a given head. In each caae the rcgiilat
device must he udjuHted so that the float wUl begin to operate by ek»*
ing the shutter when this given head is reachcKi. In order to provide for m
larger discharge, as the amount of sewage increases from year to year, 1
BijM? of the ot>ening from the chamber will be enlarged in order to giro 1
area required with the given head to produce the discharge desired/^

A special regulator has been constructed by George A. Ca
City P^ngineer of Paw^ucket, R. I., using a gate valve opemtod byJ
hydraulic plunger, controlled by the old type of Venturi meter r«
apparatuB, actuated by a fioat. In this case it was desirable to hAveiiio_
entire dry weather flow and the first wash of the streets .nt
storms taken to the treatment works, and to turn the entire •
sewer into the nearest water-course when the dilution reach eti a crrtAiii
point, reversing the operation when the total flow fell below another fU
determined amount, less than that for which the gate was c!cw<t,*ti.
sewage flows through an orifice in the bottom of the diversif^M
into a pipe upon which the hydraulic valve is established. A ♦
divemon chamber moves a vertical rod upon which are t
which controls the opening and the other the closing, oi in

valve. When the quantity reaches that for wbtch the **
closed, the tappet trips the Ventur'
operates a small valve admitting w
hydraulic cylinder and closing the valve, Whoo tlv

iimw^^m^

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uiii^mmmtt u if ifHiiniimi

Fig-
sho

prti

REQULATORS, OVERFLOWS, TIDE GATES, ETC.

607

de point at which the valve should be opened, the other tappet trips
t)i»* mechanism to reverse the Vfilvog and open the main valve. Since
the only power required from the meehanism is that consumed in opening
luid clufiing the small valves hi the pressure pipes, it has been found that
winding of the weights of the Venturt recording apparatus is suf-
ul for more than 200 operations of the hydraulic valve, A descrip-
tion of the valve will be found in the Journal of the Boston Socieij/ of
7u4l Engineers, October 1914.

At Cleveland, Ohio, where regidating valves of the walking-beam type
^ere tried unsuccessfully, the gate w^hich was operated by the float
I of the sluice class, rat her than the curved class generally employed.
The gate frame was made of cast iron and provided with a phosphor
bronze seat; the gate was cast iron. The main bearings of the walking-
beam had bronze bushings and attention had been paid in the design to
thf^ elimination of friction and opportunity for any binding of the parte»
The following note on the failure of this regulator has been furnished by
J. M. Estep, Assistant Chief Engineer of the Department of Public
Service of the city :'* The trouble with this tj^pe of regulator has been that
the sliding gate which shuts off the flow at a certain elevation of the
sttirm water in the chamber, fails to operate properly in the phosphor-
bronze slides, and I think the gat<2 probably remains open so that this
type of overflow acts just as the ordinary overflow where a diversion
is used.''

be construction of automatic regulators and the nature of the sewage

water passing through them are auch that frequent inspection is

cessary to assure their effective operation. Regulators and tide gates

bould be inspected every day, and immediately follow^ing storms the

leaning aud inspecting force should be increased so that all regulators

rliich are clogged can be put into working condition at the earliest pos-

|b|e mintitc. It is only by this means that automatic regulation will be

lactor}%

OVERFLOWS

f Storm overflows are of two types^ overfall and leaping weirs.

i overfall weir is usually constructed in the side of a sewer, and the
flow escapes over the crest when the elevation of the sewage is
that of the weu*. One method of design of such a structure is
Cfibetl fully by W. C. Parmley, in a paper on the Walworth Run
in Cleveland in Trans. Am. Soc, C. E.^ vol. Iv, p, 341.
The main sewer entering the relief chamber is H ft. 9 in. in diameter,
with a mrtximum calculated flow of 2500 cu. ft. per second* The calcu-
laleci maximum flow of dry-weather sewage is about 30 cu. ft. per second.
The intercepting sewers arc designed to carry the dry-weather flow and
1 equal vnlnni' of storm water, in order to provide for the interception

mmmm

608

AMERICAN SEWERAGE PRACTICE

of the foul, first flow from the atreeta. The required carrying capacity of
the Intercepting sewer at this point, therefore, is about 60 cu. (l. per
second. The problem was to design a structure which would alwayi
divert 60 cu. ft. per second before any fitorm water was dischnrged totb
main outlet, and one also that would not divert more than this arnounl
under any condition of storm flow in the main sewer. Mr. Parmley'i
solution of the problem is aa follows:

Supposo one aide of the sewer to be cut away and convertcvl into iJi
overflow weir such that the flow of 'the volume of water below ibe U^vel "t
this weir is not obstructed, but that all the water above its levcj ciin tli»*
charge sideways over the weir. With a given depth upon the upj>er end ot
the weir the w^ater will tend to be discharged sideways uccardiag iotlie ^'
dmary weir formula. There is* however, the forward velocity of tin-
in the sewer behind the weir to be considered. In the first unit of li. .
given quantity of water per second will be discharged, thereby miu*::*^^^
the hca«l iiporx the weir in the second unit of length; this reductioa of h**^
in the second unit of length, caused by the water dischargtHi in tlie Vf^
unit of length, will make the rate of overflow in the second nnil less ^
second than it was in the first. In a similar manner each succeeding; m.^"
of length of weir will discharge a less volume than the preceding i* ^'^'
owing to the continual reduction of head as the w^ater moves forwarc^* ^
the sewer. Tlie forward velocity in the sewer tends also to slacken, du^
the lessening volume carried. An analysis of the problem show* t*!^***
theoretically^ a weir would have to be of infinite length in order to rt^ *^
the water to the level of tlie cre^t of the weir; therefore it is not attimii^ ^';
to discliarge nil the wafer nbove tlie level of the weir, but to reduce the h^^*
upon the weir to some small amount* The problem itivolveti umv "
stated as follows:

Let Fig. 273 represent the crosB-section of the overflow dun
upper end of the weir, at the point where the water emerges froi

Let A" and Y represent the axea of co-ordinates, with the o
axis of the Bcwer. Consider this section to represent a unit len^^t

Let A be the crest of the weir, and let a + j/ be the depth of water iinr
the weir.

Let the radius of the se^'er equal r.

The co-ordinates of the weir, therefore, arc x - xi and y — — o.

How long will it require for the water flowing over the wc?if to rrdfiee iht
head of water on the wrnr from a + y to any j^iven le- i "

Let (iQ equal tlie volume of water discharged for a r af head. ^y.

and let di equal the time required for the diacliarge of the tfuaAtr

We then have the cq\iations;

dQ = 2xdtj = 2V(r* - u^)du
i Mi iui: ii»-mi II -f I/, the rate nf discharge, q^ e*\ni\i» apprv^unatn^

then

1

therefore.

REGULATORS, OVERFLOWS, TIDE GATES, ETC. 609
dQ =^qdt = 3.33(o -\-y)^^dt,

Integrating between the limits, yi and yt, for any two heads upon the weir,
gives the time required to reduce the head from yi to y^. It has not been
possible, however, to integrate this equation, and, therefore, it has been
necessary to make use of it in the approximate form:

Obtaining the At for successive differences in head. Ay, between the
limits yi and yt, and taking the sum of all these A('s will give the approxi-
mate time, t, required.

- X

Fia. 273.

Fig. 274.

This being a tedious process, an approximation can be made by reducing
the circular sewer to a rectangular one of the same average width. In this
caae, let Fig. 274 represent the cross-section of the rectangular sewer, with
the weir at A, and with an initial depth of water, y, over the weir. Let the
width of channel , w, equal the average width of the circular sewer, shown in
Fig. 273, to the left of the weir. A, In this case the water overhanging the
weir on the right is assumed to fall away by the force of gravity without
interfering with the weir discharge of the water over and back of the weir.
In this case, then, we have

q — the rate of discharge for the head y = 3.33y^:
and

Q » the total quantity discharged.
For an infinitesimal reduction in head, dy, we have
dQ « wdy ^ qdt ^ S.SSy^^dt
therefore

Integrating between the limiting heads, yi and y^, gives

, 2/1 w_ / \ _ 1 \

^, -1.67\Vy, Vj
39

i

i^-y^- V

\ 1.67V y/]

610

AMERICAN SEWERAGE PRACTICE

If Vi = Oft =^ GO , which shows, as before stated, that theoretically it would
require a weir of infinite length to reduce the water to a «ero head. The
last formula is simply and easily applied, and does not give results var]riog
greatly from those obtained from the differential equation for the circular
sewer.

If the velocity in the sewer were constant while flowing the length of the
weir, and if all the filaments in the entire cross-section had the same
velocity, the foregoing equation would give the time required to reduee

^' Sewir ^ -^

Section F-6.

Horiiontal Section above Crest ofVfeir.

Sewer 2t'

Section A-B-C-D.

Section A-B-E.
I'lC}. 275. — Weir for storm-water overflow, Cleveland.

the level of the water from one stage to another, and this time multiplied
l)y the velocity of flow in the sewer behind the weir would give the length
of weir reciuired. These ideal conditions, however, are not obtained in
pract ice. The velocity in the sewer is gradually retarded as the head becoraw
less, and, conseciuently, the sill must be lengthened somewhat in order
to perform the same amount of work.

HMGVLATOnS, OVERFLOWS, TIDE GATES, ETC. 611

By referring t^ the oauipleted design, Fig, 275, it will be seen that

the dry^weather chiitmel wm buiU upon a curve gradually ilefreasinK in

idth and .size ^vs it passes from the 14-ft, 9-in. sewer to the 5-ft. intereeptf-r.

In order to avoid ImrkwHter for partial depths of flow, a number of cal-

tilatious were made with varying depths of flow in the main sewer. As a

suit of a large numl»er of these calculations for assumed relative* elevations

af inverts of main and intereepting sewers and of varying volumes of flow,

Iho folliiwing conclusions for regulating the design of the overflow chamber

V'ere obtained:

Since it was not desirable to allow the velocity in the main sewer aJ>ove

Ihe overflow chain Vvcr to l>e reduced below about 2,50 ft. per second, it

necessary to make a drop of at lejist L50 ft. in passing from the invert

Df the 14-fl, tMn, sewer to the invert of the 5-ft. sewer^ With this drop,

Ihe minimum velocity in the main sewer will be about 2.5<> ft. per second,

when 60 cu, ft, per second are flowing. For a less quantity than 60 cu. ft.

jper second, there will be an acceleration in the velocity above the junction for

ly small vohimes of flow, and for no quantity less than 60 cu, ft, per second

iU the effect of backwater reduce the velocity t^ leas than 2,50 ft. jH»r

econd. For volumes greater than 60 cu, ft. per second, the sill of the

overflow must be long enough^ to take out all but 60 cu. ft. per second,

i^hich will remain in the sewer to be carrierl off by the intercepter. For

Ihe maximum discharge of 2500 cu, ft. per second for a 14-ft. 0-in, sewer

ticre will be no backwater efl'cct. Hence the 14-ft. 9-in, sewer will flow

[1 obstructed when nine-tenths f\;ll.

Tlie elevation of the upstream end of the weir* thereiore, was placed 2,70
ft., above the invert of the 14-ft, 9-in, sewer» and is carried to an elevation
bf 4.50 ft. above the invert of the 5-ft. intercepter after the invert of the in-
ereepter has been fixed at a proper ele\'ation as above determined. The
fade of the crest of the weir is 0.3 ft. per 100 ft. The fr>rm of cross-section
l>f the dry- weather channel at the upper end begins as the segment of the
14-ft. 04n. sewer, and, in passing downstream to the 5-ft. intercepter,
I gradually changes to the section of the 5-ft. sewer with the crest of the
^■pverflow sill n'me-tenths of the diameter of the sewer above the invert.
^H^ In order to avoid any backwater effect from the storm water ovcr-
^^PoWy it in necessary that the weir should never act as a submerged weir,
^^That is to say, the surface of the storm water in the overflow channel musL
always be lower than the crest of the weir. The storm-water branch below

Pe overflow chamber was given a drop of about 12 ft. below the level of
e sill, and was carried down the valley on a grade of 0.50 ft. per 100 ft.
le overflow branch, therefore, waa Eoade 13 ft. 6 in. in diameter*
The standard t>^pe of overflow manhole used on the larger sewers in
Ilevelaud, Ohio» is shown in Fig. 276. Attention is called to the fact
mi the gratie fur the dry-weather flow in thia catse is about 0.46 ft.
1 4-1/2 ft.
•'
:

1 Depth ol flow tn S-fL tewcr would t>c about 4,5 ft.; in H-ft. tt-in ecwcr &botii 2.7
Thn aiffereoee. 18 ft . would b*: drop hi invi-rt if wmt^t surfftcv wen level.

■The lt;Q|Clh ol tho ^-^r wjik tn.jile ribtiUt 95 ft.

612

AMERICAN SEWERAGE PRACTICE

Concerning the intercepting chambers built at Syracuse and shown in
Fig. 277, Chief Eng. Glenn D. Holmes of the Intercepting Sew«r
Board makes the following statements: "No weir is used in this lypc

\27 "Sfomti

San.S€wtr\

Fig. 276. — Overflow manhole, Cleveland.

but a small dam is placed in the old sewer just beyond the chamber.
The dam is usually built with flat slopes on the upstream and downstrean
sides tx) give an effect similar to that of the throat of a Venturi meter.

Bl. 14.35 1

Vertical Section.

Fk;. 27

Horizontal Section.

-Intercepting chamber used at SvTacuse.

Matcriiil stranded behind the dam is washed out during flood discharges.
There have l>cen a number of stoppages in these interceptors due to
dei)osits in front of the small outlet pipes leading from the chamber."
A marginal conduit has been built along the Boston shore of the

fSGUlATORS, OVEIiFLOWS, TIDE GATES, ETC.

&13

River to carry off the storm water from the area tributary to
vor. This was necessary" because of the construction of a dam
the river between Boston and Ciiml>ridgc, converting a portion
b^re on either side into imusually attractive property facing a
^Hr bn^in. The marginal conduit was designed to carry off the
Em wash, which contains most of the dirt from the streets oml
pollutes the water of the basin in an undesirable way. ^Vs
Itriet is closely built up, the area in question is practically im-
us and after the first storm-flow had carried off the dirt, it was
It that there w^ould be relatively little more to be expected diuing
>rm, Tlie main conduit was provided, therefore^ with a number of
hambcrs, Fig. 27S, discharging the excess storm water Into

sewers leading to submerged outlets.
erfiow chambers were designed by E. C. Sherman under the
of Hiram A, Miller. A curtain waU partially separates the
mber from the conduit, so that sewage is drawn from the

' S€ction. Longitudinal Section.

[j» 278. — Overflow chiunber, Boston marginal conduit.

of the stream and floating ddbris cannot be carried out into
h-water basin. The water in the basin is retained at El. 108 and
\y tiled that a loss of head of 0.5 ft. would be caused by the

\x _ k gate, the crest of the overflow troughs were placed at

te.5. The top of the conduit being at El, 106.2, the conduit ifl
a alight liead at times when the overflow takes plaee. As soon aa
Dughs are filled, the head on the check gates causes them to swing
and permit flow into the basin to take place through the sub-
►fi outlets.

0%'crfluw chamber of unusual arrangement was constructed in
ci about 1809 at a point where a brick sewer was crossed by a
brick conduit at a somewhat lower level, built in that year in
^ oarrj- the storm water from an area of about 650 acres, including
known as Tenean Creek. This conduit was 9 ft. high
wide at the crossing in question. The brick sewer wai
2i ft. wide; where it crossed the conduit a reducer
ami a 30'in. pipe inserted in the arch of the conduit
Fig. 279. Thu overflow channel starts from a chamber

614

AMERICAN SEWERAGE PRACTICE

which is separated from the sewer by a dam and weir; at the oiilM
of this chamber there is a 3-ft, tide gate to preveat water in the dra

from passing up into the sewer. Below this gate the ovcrflv* ^ ** '
wide h-' * ^*- * U\. high and enters the drain at an angle of tiO deg.

HEGULATOm, OVERFLOWS, TIDE GATES, ETC. 615

616

AMERICAN SEWERAGE PRACTICE

At Hartford, Conn., when a sewer system is being coDBtructed for i
district, "a number of local sewers are brought together into a trunk
sewer," according to information furnished by Roscoe N. Clark, City
Engineer, "which is carried to a point near the intercepting sewer,
from which one pipe, to carry the sewage flow, is built to the intercepter,
and another, large enough for the storm water, is built to the river,
brook or storm-water culvert, as the case may be. In this caac »
weir is built across the overflow channel with its crest at the top of 1^^

' Invert of Pt9S9nt6mm'
Vertical Section A- A.
Fia. 281. — Stop-plaiik regulator, Hartford.

sewage pipe, or above it, if it is desired to have the sewage pipe wo. "^ .
under a head, as is soinctiines done." Examples of this are shown
the group of storm overflows illustrated in Fig. 280. The overfloi^^'^
at Bonner Street is a rather unusual one, because the overflow has beC^^^^
dropped to go below the intercepter; in most cases the interceptiit^ ^
sewers are the lowest at cro.ssings of this kind.

Where relief sewers must be built to take part of the sewage flowin^^y
in old sewers past certain points, use is made of weirs, as in the case ^^^-^
intercepting sewers. For example, in the case of the old Hartf or -^

i

REGULATORS, OVERFLOWS, TIDE GATES, ETC. 617

sewer shown in Fig. 281, it was desired to remove practically all of the
storm water but to keep the sewage in the old line. The latter was
closed, except for about 3 in. next the invert, by an adjustable stop-
plank which was expected to divert everything but the sewage into the

Fig. 282.-

General Plan.
-Twin overflow manholes on relief sewer, Hartford.

^ew sewer. It was found in practice, however, that the height of
^ in. was not enough, and 6 in. would have been better to prevent the
opening becoming clogged. Another unusual Hartford connection
*>etween an old sewer and a relief sewer is shown in Fig. 282. There
^VB two overflow manholes, and the crest of the weir in each, constructed

PWHge must have its velocity checked before it is discluirged at the
»iilkhead line of a pier 455 ft. long. To accomplish thijs a combineci
traiisforincr and overflow chamber was built {Eng. Record^ Feb. 15,
L9(XS), The transformer chamber, lug, 283, is about 6 ft, long and is
It the bead of the overflow chamber, .so-called, which is really what
iritish engineers call a stilling chamber. It is 65 ft. long and hs
►ur|x)8e is to reduce the velocity of the storm-water discharge by pro-
riding a greatly enlarged channel. This chamber and the 15-in. storm-
/atcT drain serving an adjoining railroad yard end at the bulkhead Hne^
Pill the dry- weather flow is discharged through a r2*in. cast-iron pipe
►arri^'d under the pier floor on slings to its outer end.

Leaping weirs consist of openings in the inverts of sewers so con-
iict«d that the ordinary' flow of sewage proper falls through the open-

\ '^■''^ Cement Concreh

Fig. 285. — Leaping weir for pjpo eewcra, Cleveland.

^uga and passes to the intercepters. At times of storm, the increased
*<!l(H'ity of flow causes most of the sewage to leap the openings and pa^^n
*ii down the sewers to the storm outlets. The first use of the device

commonly attributed to J. F, Bateman, designer of the first water
^orks of IVIanchesteri England.

The firat use of the leaping weir ii^ this country is believed to have

Dn in Aiilwuukee, where 12 branches to the Menonionee intercepter
i^cre connect4?d by means of leaping weirs in 1887 and subsequent years.
>l»ie of lhee*e connections is shown in Fig. 284.

Tlie most simple type of leaping weir is that in which the dry weather
flow drops through a slit cut across the invert of the combined sewer.
[Huch a weir used in Cleveland, Ohio, is shown in Fig. 285, The type
U uiied on the smaller sewers and is known locally as the weeping weir;
tcir larger sewers the manhole shown in Fig. 276 is preferred. Re-
garding (he former Mr. Estep states: **In the smaller systems this type
fci »kHKjt AS satisfactory as can be installed. We n»ake calculations as
l« till! amount of dry-weather flow in each case from the aerenge, and

620

AMERICAN SEWERAGE PRACTICE

TABLE OF DIMENSIONS

Sixe

k

B

C

Ra

Rb

Style

I5fn.

<jV

sh'

/^V

7V

7-

>l

18 in.

/^v

7'

/^'

$'

^i*'

a

Min.

??^^

9ii

f4i4

12'

//V

C

#i4.-i^

t-C2

[:)

JC

1

i^

Styles A.B.C.

Details of Weir Conitings.

Style D.

Jgiji.^ 5'(?' — .J,^i,r-

Sectlon D-D.

Uongltudiruil Section.

Section C-C.
FiQ. 286. — ^Leaping weir used in Syracuse.

REGULATORS, OVERFLOWS, TIDE GATES, ETC.
compute the size of the opening required to pass thia amount of

In one branch of the intercepting sewer system of Syracuse, N. 1c .,
i>w (HUB) under construction, leaping weirs are used at the connections
\ existing sewers with tJio intcrcepters and float regulators are also em-
k>yed to safeguard the intercepters agaiui^t surcliarge. The type of
m employed at Syracuse is shown in Fig. 280. It is formed of a
ipc, inclined upward so as to contract the flowing stream and
ti ating ctTort. During dr>^ weather when the quantity of sew^age

I umali and the veloc.it>' i^light, the sewage merely drops ovex the weir
y the channel loading Ui the intercepter. At times of storm flow, the

^di'5^W€rh'p§ .

Banff Riim\2i-30

^W9fwrBair9$

wffftnwtn'

&

^'4

^

n

—

".I."

□

._:

1 —

r(¥

7i

H

"^l*

/

y

Ru

7S

2f\

2)

—

/

r"

,_

^

TFj;

ft

7^

W

/

r-

z

0 ai a2 a^v 0.4 0.5

2i)

1,0 \5

Total Diftchar9ef cu.ft-. per ftec*
Fio. 287. — Syracuse le^iping weir experiments.

KcretyifHi velocity causes the greater part of the sewage to leap the open*
g, and it b caught in a cast-iron trough which may be adjusted in posi-
tion, so as to vary the width of opening. Several of these weins have
been in \im for periods up to 3 yejus^ and have given good satisfaction.
The only dillicvdty experieneed has been when foreign matters, such as
nigif ancl sticks^ have clogged the oix*ning.

Testfl were made upon a model weir of this t>'pe under the direction of
fr[rrm D* Uolmes, Chief Eng. of the S>Tacuse Interceptiug Sewer
Board, the results of which are given in Table 166 and Fig, 287.

Another methi>d of constructing a leufjing weir with an adjustable
••vi-irh of o|r>etHin;, as suggested in Moore and Silcock's *' Sanitary Engi-
i>t* ring/' is shown in Fig. 288. The following analytical tTcatment
i*f the device is taken from tliat source, where it is credited t« Prof.

^UM

622

AMERICAN SEWERAGE PRACTICE

Table 166. — Syracuse Experiments with Leaping Wbibg

I, Fio.

287

{Qlenn D. Holmet)

Run

■upply.

ne.-ft.

ceptod

Difl. at
outlet,
aec.-ft.

IHttmtaiQta, ft., Fi«

.287

A

B

C

D

E

, ;.,

1
2

0.5
0.15

0.2
0.15

0.3
0 0

-

0.4

0.4

0.17

1.08

0.21

0.75

0.4

3

0.26

0.2

0,07

0.4

0.4

0.20

1.21

0.25

1.17 0.4'

4

0.36

0,21

0.21

0.4

0.4

0.24

1.27 ;

0.26

1.00

0.4

5
6

0,70
0 124

0.22
0.12

0,48
0.0

0.4
0.4

0.4
0.4

1

0.19

1.04

0.25

0.8

0.*

7

0,512

0.2

0.29(?)

0 4

0.4

0.29

1 35

0.25

1.2

0.41

8

0.438

0.18

0.12

0 4

0.4

0.25

1.25

0.25

1.05

0.4

1 ^

0 407

0.19

0 19

0.4

0.4

0.27

13 ,

0.25

1.12

0.4

10

0.708

0.19

0.5

0 4

0.4|

0.34

15

0.25

1.3

0.4

11

0.862

0.25

0-62(?)

0.4

0.4

0.36

1.50

0.25

1.4

».*'

12

0.4

0.16

0.06

0.4

0.4

0.20

1.17

0.25

0.93

0-4

13

0 268

0.18

0.06

0.4

0.4

0,21

1.2

0.25

0.96

ft -4

14

0 443

0.21

0.22<?J

0.4

0.4

0.27

1.3

0.25

1.10

0 -1

15

0 731

0.22

0.40

0.4

0.4

0.31

1.4

0,25

I 25

0 -4

16

0,758

0.22

0.52(7}

0.4

0.4

0.34

1.5

0.26

1.4

0 -*

17
18

0.4
0 4

0.4
0,4

0 . 1
0- 1

0-28

0 67

0.39

1.55

0.25

1.4

ig

0,28

1.09

0.4

0.4

0.44

1.7 !

0.25

1.5

0.4

20

0.32

1 . 13

0.4

0.4

0.44

1.7

0.25

1.55

0- 4,

21
22
23
24
25
26
27
28^
29'

0.2' dam

0.2' dam
0.2' dam
0.2' dam
0.2' dam
;0.2' dam
0.2' dam
0.33
0.55

0.31
0 31

0.27
0.29
0.31
0.31
0.20
0.33
0.52

0.67

1.05
0.05
0,11

0.20
0.93
0.00
0.00
0.01

,.

,

1 - -

..

,v, ::::::

^

^

0.3

0.6

0.27

1.4 :

0 25

1.25

0*

4

30^

0.52

0.05

0.3

0.6

0.30

1.45

0.25

1.2 lO- 4

31
32
33

0 55
0.55
0 .■>5

0.20
0.2S
0.69

^

.. -_

_

» Dam 0.2 ft. high in discharge pipe.

Let h be the head of water over the upper lip of the opening, x the hori-
zontal distance from the upper lip to the edge of the lower lip on the fartlwr
side of the opening, and y the vertical drop from the upper lip to the edge
of the lower lip, and t the time for a particle of water to pass from one f
to the other. For practical purposes, the mean velocity of the water will ^

V = 0.67\/{2gh)
y = o.^gt' _
X = 0.67l\/(2gh)
y = 0.56x« -^ h

HEGVLATOm, OVEHFWWS, TIDE GATES, ETC.

623

;iveB the width for*any given difference of level which the jrt will
k'er with a hojid h. If in addition there is a velocity of npproacli,
dudo the heud necessary to give that velocity viz., v^/2g.

VenHca* Section.

— —

^

^ *^

"fe^^^-

i ^

%/7<rr!; q^— ar

i.

todfreamX

^^

IJ 1

1

JetViT^ir A

. ' ' ^ - ^/'/y-y^f///y/y^~^J'///y-jyy/.

^

Sectional Plan.
FlQ. 288.— An adjustable leaping weir.

Pbambers. — One of the objections lo practicafly all diverting
that silt is diverted into the intercejiting sewers and b
Kruiljitr in till' space reaching from the weir lu the in-
Ifiggowfur. ^ silt brought down by dry-weather fiow^

•a juajit; the bottom by storm water is accumulated

624

AMERICAN SEWERAGE PRACTICE

in this space. This is likely to give rise to deposits. Even in so care-
fully designed an overflow as that at Cleveland, where there is no dead
space behind the weir^ the silt dragged along the bottom by storm wat^
cannot pass the weir but must be carried on into the intercepting sew^c^-

Horliontal Section C-D.

Vertical Section A-B.
Fkj. 2S9. — Overflow and silt basin, Harrisburg.

In some cases particular care has been given to the design of basin^ ^
which the silt carried down with the sewage can be retained and p'^
vented from passing into the intercepting sewer. Two different ideis
have been followed in designing such basins.

REGULATORS, OVERFLOWS, TIDE GATES, ETC.

625

In one case a sump is constructed to retain the silt, forining practically
a catch-basin from which the silt can be removed from lime to time,
in example is shown in Fig, 289, an illustration of an overflow and
tit basin used at Harrisburg, Pa., built from the designs of James H.
Pucrtes. consulting eagmeeF, Now York City, The drawing requires
no explanadon.

In the other type a depression is formed in the sewer, above the

egulator, »o shapcni that the silt will be scoured out by storm flow^ and

learned down the storm sewer to the overflow. One of the best cx-

aples of this type is seen in the illustrations of the storm overflows at

Washington, DX\, Figs, 270 and 271. In the first of these overflows

Jthe silt chamber consists of a depression in the invert of the main sewer.

This is suffioicnt to retain the silt brought down during ordinar}"^ times*

|At times of storm, when the regulator gate is closed^ the high velocity

cours out the accumulated silt and carries it over the dam to the storm

Ival^r outlet. In the second illustration there is a silt basin of con*

|»iderable size in the chamber above the regulator gates* By opening a

kiuioe gate at the side of the chamber at times of storm flow^ the aiJt

can be forced into the storm scwcr itself.

An objection to either cf these designs is that an opportunity is
'afforded for organic matter to accimiulate during low flows and to
putrefy, thus forming offensive pools of sewage.

. putrefy, t

Strtctly

OUTLETS

StrtCtly speaking, the outlet of a sewerage system is the end of an

^outfall sewer at which the sewage is discharged. There may be a

number of these outlets in case the city has several storm water outfalls

Df overflows. In every ease, the object should be to discharge the

ewage at a point where its presence will cause no offense; the disposal

Df the stcrin water is not so difficult because it contains less organic

Imatter and is not delivered continuously. Where the water Is quiet

be outlet of the outfall sewer is usually submerged to a considerable

depths while if the sewage is discharged into a stream flowing rapidly

ic all times, the outlet need not necessarily be submerged, provided the

t2W/ige pjisses into the stream at a point w^here it is certain to be carried

I way and dLspersed rapidly. In the case of outlets in tidal waters^ the

luL't that it is generally impracticable to place them so high that they

t^ill ' ' led at high tide, results automatically in cheoking

the 1 -;e during tht* portion of the tidal flow when it i^i

kfly to km swept back along the shoro^ and accelerates the discharge

irhen the tide is going out and the hydraulic grade of the outfall is,

Ihercforft, being steadily increruicd.

A different outlet is sometimes built for combined sewers than for

40

626

AMERICAN SEWERAGE PRACTICE

those carrying nothing but sewage^ because the latter must be did
charged with much greater precautions to prevent nuisance than ti
storm water flowing from combined sewers or drains* A combinatia
of these conditions is illustrated in Fig. 290, from Engineering Rtrn
April 8, 101 L This outlet was built at Minneapolis, where the level (
the MissiMsippi, into which the sewage is discharged, fluctuates mat
rially* The conditions made it practieable to build a double outle

by which the dry-weather flow i
carried out farther into th
stream and to a lower level than
the storm water. Two 15-in,
cast-iron pipes run out below the
paved apron in front of the
storm-water outlet, and discharg
the dry-weather sewage 5 ft. 1
low low-water level in the riv<
The invert of the storm wat
sewer is 9 in. below the hig
water level in the river, so
the sewer will have a free 6k
charge at all times.

Much the same plan is followTed_
in the outlets of the seweraj
system of Winnipeg, built fron
the plans of CoL H. M. Rutta
The outfall sewers are built
concrete until they approach t|
banks of the rivers into whi^
they discharge. Each outfall
then continued by a wooden «eiP
i£/^so nmning out on pile bents at an
Section through Og tier. '" clevation of 3 or 4 ft. above I

Fm. 290.-Dry-weather outlet, Minne- "ver, Ita outer end is clowd I
apoliS' a large flap door, which 0oal8 i

ward when the Hver is in flc
About 10 ft* from the outlet end, a small pipe drops from the invert i
is then carried forward on piles 50 ft. or more beyond the end of tl
main outlet, to take the dry- weather sewage well out into the strea
in times of low-water* These outlets are protected afj^ainst the IwmH
ice flows by a sloping ice-break of 6 X ti-in. timber, laid so ss t4i c«
the ice over the structures.

Where the sewage must be carried out into comparatively deep wai<
the outfiill sewer is generally a cast iron or steel pipe ending in a qua
bend or a tee, by which the sewage is discharged upward* A i^i

Section and Plan through
Dry Weother Outtet*

mmm

REGULATORS, OVERFLOWS, TIDE GATES, ETC. 627

ijtlet of this cliarocter was built in 1913 tn carry the effluent from the

iochester sewage treatment works into Lake Ontario. The pipe is 66

. in diiimeter and made of half-inch plate, the straight portions being of

\ke I^ck-bar type with single riveted seams every 30 ft., and the bends of

bort sections with double riveted longitudinal seama. The submerged

ortion of the pipe was laid in a dredged trench 8 ft. deep until a depth

35 ft. was reached, when the trench was shallower. The miniiimm

ck-fill over the pipe was 2 J ft. The pipe terminates in a timber crib

I ft. from the ahore, and the discharge is at a point where the water

about 5C) ft. deep. The crib or outlet structure is 46 ft, square by 24

high, built of 12 X 12-in. hemlock timbers laid to form 25 pockets

3F

t^

VxOi

^/O

Longttudinal Section «

,^je.v

W--^

^^

:t:^-T

^

-,d^ 1

'6

i^

k:

%

kl

c^

^

^

^

^

k

«6"

e'"-"

^

"^A

^

**^

'>

i

Section
A- B.

End Elevatfon,
Fig. 29 L — ^Outlet of joint tnink sewer, New Jersey,

are filled with stone except where they are occupied by the pipe,
pttom of the crib is 3 ft. below the bottom of the lake and i^^ f^ur-
punded with riprap ejctcnding 10 ft. up the aides of the structure. The
:>p ia 20 ft. below the mean low-water surface of the lake* The pipe

Bcharges 10 ft. above the bottom of the lake, being raised as it passses
b rough the crib* Built into the crib near the outlet, is a three-way Tec,
he aide openings being 38 in. in diameter. This was placed to provide
^r future extensions in case it is deemed necessary to discharge the

3ucnt at more than one pointy to promote njore thorough dilution.

The outlet of the joint trunk sewer of Northeastern New Jersey, on

J shore of States Island iSound, is illustrated in Fig. 291. Like many

628

A AMERICAN SEWERAGE PRACTICE

of the outlets in the vicinity of Xei^ York Bay, it ii* below a wharf, wtm^i

was constnicted in this cjise in return for permission to I'Stabliah tti'

at this place. The wlmrf is 00 ft. wide and about 40 ft. loji:

the dock line making an angle of about 75 deg. with the uxi^

The 72-in. brick sewer terminates in a brick chamber 7-1/2 ft, s'

the upper end of the wharf, from which a 3tVin. east-iron pipp «

distance of 36 ft. to the bulkhead of the wharf, where its crown is J

below low'tiile elevation. This pipe is carried on piles indf-

the wharf and is said to have enough capacity to disrharg*

hne, where there is a strong current, a volume of sewage equal lo IM

delivered to the chamber by the 72-in. sewer. Owing to some doaM m

to the stability of the foundations in this vicinity, the last 80 fi. of \hf

brick sewer rests on a 4-in. plank floor 8 ft. wide, supported '

10-in. stringers which are carried by three rows of piles. Tr

was designed by Alexander Potter, Chief Eng, of the pomniisstou

representing the seven communities interested jointly in the work.

The outlet of the southern outfall system of Louisville is shown is
Fig. 292. It is at the end of a sewer 10 ft. 1-1/2 in. high anil 10 ft
7 J in» wide. It includes a drop chamber 93 ft. long, built cn «»&•
Crete piles on the steep incline running down to an otltlel stniefim M
ft. long, the foundations of which rest on rock.

The crown of the outlet wDl be below the surfacg of the wator to thf
river at all times after the proposed 9-ft. stage of the Ohio recomnumdid
by the War Department lias been established by Congreas. BeCoiw
that time there may be occasions when the outlet will be partiiBy
exposed during extreme low water; during floods the river rises many firl
above the outlet, the maxim urn being probably about 70 ft.

In determining the size of the drop and outlet structures, a hydfatiiit
grade was assumed from the top of the scwor at the upjxir end of tie
drop chamber to the surface of the water in the river when at EL 4li
or 32 ft. above the elevation for the 9-ft, river stage. T
rarely exceeded during freshets in the winter; in June r
water has exceeded this stage only twice in 35 years, and remained *b^f
it for only a very short period of time Lhen. Storms of great tnlMirSy
are not frequent in this locality except in June* July and Augtist, aai
are very rare during the winter. The p^ :jeiUTe«cr J

rainfalls of such high intensity as to tax ^ / , '^ ^*jfr^. ^^

curring at a time when the river is above EL 415, was eottsi" 1
engineers in charge of the work to be very remote, and for tf i : .
was bebevcd to be safe to base the design of the ditjp and oi/J* t ^t-^.
lures upon the hydraulic grade mentioned. The outbt .tinv vn^ .. j
generally be submerged in the river, and oooaisionally at tii-
extreme floods the entire drop ohamber and even the outiall irv
will be sttbmcrged for some distance. It was oonsidcnjd imposQi?^ ^

630

AMERICAN SEWERAGE PRACTICE

provide adequate drainage in the oify during storms of great eeverily
occurring at a time when the river is at an extreme flood stagev Such
conditions are so rare that they must be construed as an *' act ol Provi-
dence," lot which the city should not bo expected to make provimoo.

There have been indicationjs of a strong tendency of the river bank to
move toward the river after the falling of the ^'ater in the late spring or
summer. The bank is composed, to a large degree, of silt, which be-
comes saturated during high stages of the river, and is very heavy when
wet, possessing little stability'. Underlying the silt is a bed of
sand and gravel, through which large quantities of water are
continually toward the river. The action of this water at the surface oi
the gravel probably tends to assist the sliding action of the silt abwo.
In anticipation of any such action and its consequent effect upon the
sewer at its outlet, the foundation was carried down to bed rock, u
illustrated. For a short distance, 15 ft.^ the rock was excavated to &
depth of 4 or 5 ft. and the foundation carried down in this pit to form ft
key to guard further against any movement.

The drop chamber was built on piles to assist in resisting any possibte
movement, as well as to support the structure in ease, by any chance, ii
should be undermined by the action of the river. These piles extend to
the rock where it is within 20 ft. below the masohrj% and 20 ft into tlifl
ground further up the bank, in all cases penetrating a long distance ill
the gravel underlying the silt.

The outlet structure is 8 ft. wide and 8 ft. high, with a semi-circultf
arch, vertical side walls nearly 3 ft. high, and a comparatively flat hut
curved invert. At its outer end two wing waUs were built out into the
river, each making an angle of 45 deg, with the axis of the sewer.

The drop chamber has an arch, short side walls and invert of the sa
dimensions as those of the outlet structure. In the center of the invtd-t,
however, there is a channel 3 ft. wide and 2 ft. 10 in. deep^ line<l wit
half-round vitrified sewer pipe. This channel is for the dry-weatJ
flow, which will have a very high velocity. The pipe linit*
rather than vitrified brick, because of the absence of longitu
at which inverts on steep grades show the great<?st amount of erosifl
and for its good wearing qualities. On account of the velocity whw
will be obtained during the lower stages of the river, both the outlet a»n
drop structures have been lined with vitrified brick to the top of the sinf
walls.

The outlet of the northwestern sewer in Louisville is of \\v
general type but illustrates a different metliod of supporting ^" -
structure. The cross-section in all places is 6 ft. H jn. widin by 6^**
high, Fig. 293. The outlet is submerged by the propo^^
the Ohio Rivor, For a distiirue i)f 77 ft. from the head \^

lEGULATORS, OVERFLOWS, TIDE GATES, ETC, 631

HSGVLATOHS, OVERFLOWS, TIDE GATES, ETC. 633

f. ,;;ii- > PorrL Cem. Concrttf'
■^ 5t^€tffod%

Trons verse Section.

I Oranilw Cufwattr wtth li 'boihpi Casinq^

.^ b AnchifrFhf^t

? - - ' 80' ' —

Part fhrtLUfmtrt

(f Part fhrtt, Ufrm

Horizontal Section,

I 0 i) 0 , . V . .

19 Qt&C

-J

gdgi) 1111(1113

Tmn&vcrsc Sectfori A- A.

Pxo, 295. — Increiiser chanibefj Brooklyn.

Transverse Section

REGULATORS, OVERFLOWS, TIDE GATES, ETC. 635

^The outlet of the 92nd Street sewer in the Borough of Brooklyn,
York City, shown in Fig. 295, includes an increajser chamber, 80
, loag, extending from the end of an 11-fl. sewer where it emerges from
tunnel to a triple sewer having three basket-handle sections carried out
I a riprap embankment far enough for the sewage to be discharged into
artion ol the Narrows having swift tidal current. The whole structure
jveiy heavy, ownng to the strong current to which it is subjected, and
to the fact that it may be utilized in the future by the Municipal
Bpartmcnt of Docks and Ferries. The bottom at the site of the outlet
|roarae shingly gravel, wnth a lower stratum of compact sand and gravel.
Fig, 296 is 1 he outlet structure for storm-water of the high-level inter-
f>ting sewer in Washington* The water is brought to the structure in
^o 12-ft. channels with arched masonry roof. The outlet structure is
>vided with a roof of concrete between I-beams spaced 3 ft. 6 in. apart.
The outlet has a longitudinal wall 30 in* wide which supports the inner
end of these beams along the center line of the structure. The general
^arrangement of the structure is sliown so well in the illustration, from
^fcawings furnished by Aba E. PliiJlips, Superintendent of Sewers of
^Be District of Columbia, that no explanation is nece8sar}% The entire
^vucture is carried on piling spaced 3 ft, 6 in. on centers in each
^Drection for the most part.

TroE GATES

[Wherever an outlet ends at a body of writer subject to considerable
Botuftlions in level and it is necessary to prevent this water from enter-

: the sewer, a backwater or tide gate is employed- This consists of a

fcp hung against a seat which incUnas backward as it rises. The hinges

ly he at the top in case the gate consists of a single leaf, as is usually

ease, or tliey may be at the side, in case the gate consists of two

^ves.

[One of the earliest types of large tide gates to work satisfactorily was

ckt danigned by Otis F. Clapp while in charge of the sewer department of

LividencCp R. I., of which place he subsequently i>ccame city engineer.

iiid is shown in Fig. 297, from Erig. Record, Aug. 29, 1896.

rdinarily the entire flow frrm the 24-in. lateral sewer dropped through

rack, /?, in the bottom of the chamber, A, into the intercepting sewer

; a lowor level When tiie volume of sewage became too great for the

prcepting sewer, it rose in the chamber, *4 , and swung open the gate,

, fi*D an to obtain an outlet tlirough the storm scwcr into Narragansett

ay* The gate, G, revolved about its axiB, B, and ab^o al)Out the axis, C,

i that it moved freely even with a shght flow of sewage from the chamber

^"^Hcn the tide backed ujj to the storm sewer, the gate was pressed

t ibt flietit. The adj usl ment of the gate in position was readily

636

A Af ERIC AN SEWERAGE PRACTICE

made; by means of the nuts D, The viiiuaiml feature of this design is
the use of very long links for hclding the gate.

For a number of years, the larger tide gates in Boston were frequcnllv
hinged at the sides. Each gate consisted of two leaves, and bs the ^if^^
was inclined with the top inward, as usual, when the gate opened i^
rose slightly as well as moved outward. Conj?equently it tended to
fall back again when the pressure of the outflowing atorm water »i^^
sewage decreased. In order to make certain that this closing should t^^
place, it was cuistomary to hitch to the back of each leaf a ''bridle chai^

1 ' r-j t *-

W ^ i

ftvm

longituciinal S«chorv. Cro4S Section

Fto. 297. — Tide gates at Providence,

hanging loosely from a substantial eye in the roof of the n
On the lowest part of the chain aa it hung between the roof m
gate was a heavj^ weight. This bridle chain tended to ctoee the
when they were open. This type of gate was known a» the ** btir •'
and has now been abandoned on account of the number of adji
which were necessary to keep it in c<t
chains aecunmlated large maaaeis of float i
with their proper operation.
The tjTM? of tide gate and chaiuber nr '- ^ ** !* *^,i.m u-.

/ - •

'A*i

■ Vx\ ^^

^. 2^8. It will be obgen^ed that the wooden gate rests directly on

I if of the rnet-iron scat, FonTierlj^ the seat was a heavy wooden

J,' vith wUch the flap made a tij?ht joint by mcana of a rubber

«ket slightly receded along each edge, so tliat the nails used in hold-

REOULATORS, OVERFLOWS, TIDE GATES, ETC,

539

5€cffon,

15'
J

^

Fia. SOO.^Detaila of WajshingtuQ tide gates,

to the wood would not project and interfere with the proper com-

ioa of the rubber when tlte gate was subject to back pressure. The

of gate illustrated b regularly made for 12, 18, 24, 36» 48 and G(>-

outfalls, by the Gibby Foundry Co., from the designs of C. U, Dodd

640

AMERICAN SEWERAGE PRACTICE

who patented the novel features. The timbers arc held togflbir'l
vertical binding rods, and in the lower part of the flap a number of
displacement weights are inserted, which serve the same puiposi! m
the bridle chiiiD in the older form of side-hinged gates, A hirger piit
of the same Renerxil type^ also designed by Dodd for use in Boeton, ii
shown in Fig. 299.

The tide gate used in Washington in the structure iUustrated in
Fig. 296, Is shown in Fig, 300. Asa E. Phillips, superintendent of tlie
Sewer Department of the District of Columbia, informed I lie authors
that these gates are made of double cross lapped 3 X 13-in. Gwfipa
pine, shipped directly from the southern mill where it ia cut and kept
under a damp cover until ready to place. The contact is made on the
concrete gate seat by a rubber strip 3 in, wide and 1 in. thick* sot blf
into the wood. These gates have been very effective, requiring itcarccly
any attention, and have always been substantially water-tight. Tlifj'
recjuired no renewal or repair for 5 years after their erection, aod veiy
little for a number of years longer.

The operation of tide gates by hand has been attempted :v
as at Hoboken, N. J., where there were three thus served in I '
one which waa a simple automatic flap gate liJce tho^e in Boston.
James H. Fuertea found in that year that there was ao attendant »t
each manually operated gate all the time, 12-hour shifts being la force*
and ea43h man followed a system of his own in managing the gatet. At
one place the gates are opened an hour after high tide and cloijMjd an
hour after low tide, with some variation during very high or low ilda^
At another place the gates are opened from 3-1/2 to 4 hours aft "^ '^
tide and closed from 2 to 2-1/2 hours after low tide. Obtr
showed Mr. Fuertes that the proper time to open the gates wa.^
after high tide and for closing them 2 hours after low tide, ai. :
the automatic gates would probably give better service than roftnusl
operation of the kind likely to be provided.

VENTILATION

For many years the provision of special structurea to aid the yvmi
tion of sewers was one of the most troublesome tasks of the dc»t|
The gravity of the problem is probablj^ not appreciated to-day, whf^nl
necessity of good grades and constructJon is so generally rt'

that the conditions w^hich frequently faced a city engineer no.

more than 25 years ago are hardly to be believed. Wlien the aewrtp
systems frequently contained old sewers which hafl rilher
constructed as to cause the formation of banks of sluiigc audj
septic sewage, or hiid been allowed to fall into such a dilan
tion that the same evil results followed, it - : ' ^ t- -

REGULATORS, OVERFLOWS, TIDE GATES, ETC. 641

ell sis the general public had good reason for believing that there
i 8iich a thing as ''sewer gas/' There were a number uf books written
^n the subject of this "gas*' and it was naturally seized upon as an
iplanation of various diseases of city dwellers, although the relation
ptween the two was diflReult to perceive. The result of the offensive-
ftcse of the air in many sewers w^as the practically universal use at one
pme of main traps between the sewers and the plumbing systems in
milding^. The presence of these traps resulted in the impossibility of
jrentilating the sewers through the soil pipes within the buildings.
In some cases, however, ventilation was afforded by a pipe run up
om the house drain, just outside the main trap, and generally carried
Dve the roof on the outside of the building, although this position was
ften impracticable and substitutes were made for it, one of the worst
being to have the ventilating pipe terminate in the "area'' in front of the
bo\ise. a foot or two above the ground . Many other methods of ventilat-
the sewera were also tried. One of the most obvious, which is still
ctensively employed, was to use perforated covers for the nuinholes.
U. one time perforated trays of charcoal were placed in the shafts of the
aanholes, in the behef that the sewer air in passing through them
rould be disinfected. In order to increase the draft up the vent pipe on
be faces of the buildings, many kinds of cowls to surmount them were
"invented. Some of these risers were provided wnth a bent pipe admit-
ting fre^h air to their interior in a vertical direction, with a gas jet in the
enter of the vertical portion of this inlet, so that the flame of the jet
ew a current of air constantly into the riser and also helped the upward
raft in it from the sewer. Ventilating street lamps have been installed,
particularly in British cities, in which the air is drawn from the sewer in
pipe and sucked up a shaft resembling an ordinary gas lamp post, by
be draft of a gas lamp, through the flames of which the sewer air mujat
pass before it can escape.

With the steady improvement in the construction of sewerage ays-
ems and the abandonment or rebuilding of the old lines which were
iefective, the annoyances due to foul odors became so rare that it oc-
jnrred to many engineers about the same time that the necessity for
fiain traps no longer existed where the sewers were in good condition,
and that the ventilation of these sewers w'ould be greatly helped by the
pmission of such traps. This opinion led to a number of investigations
the real nature of sewer air. One of the first of these was made by
Parry Laws at the direction of the London County CounciL He found
bat the bacteria in the sewer air were related to those in the external air
nd not to the bacteria of sewage. The inference }ve drew from this was
bat no matter how many germs of disease might be in the sewage they
^ere not likely to enter the air above it unless the sewage splashed
iolently, as would be the case at the entrance of a branch sewer into

41

642

AMERICAN SEWERAGE PRACTICE

a trunk sewer at a comiderably different elevation, or where ftie »cwj^
fell down a manhole shaft. There was litlie probability, in liisopinu)
of bacteria passing from the walls of a sewer to the air, after the ^*w»
level had fallen, because he found in one ejcpcrinient that an empty pi|5(
sewer, io which large numbprs of baeteria must have been attnr.ha
effected no increase in the l>acteria in a current of air sent through i
Although his experimental evidence wsa contrary to the probabihty t
sewer air containing disease germa not found in external air, he neveJ
thelesa drew the following conclusions:

•* Although one is led almost irresistibly to the conclusion that the «
ganisnis found in swwer air probably do not consiitute any sounn? ofdiui^
it is impossil»le t<i ignore the evidence, though it be only circumstiintiil
that sewer air in some rases has had some causal reflation to xymolir discai
It is quite conceivable, though at present no evidence is forthconiiti|c» til
the danger of sewer air causing disease is an indirwt one; it may ronl*
»ome highly poisonous chemical substance?, possibly of an alkaloidat natu
which, though present in but minute quantities, may nevertheless produa
in conjuaction with the large excess of carbonic acid, a profound effect up
the general vitality.**

In 1907 Dr. W, H. Ilorrocks found at Gibraltar that where sewage W
verticdly the air in the sewers contained the colon bacillus and vano
streptococci. He also found that it was possible to put easily
nized forms, such as B, prodigiosus, into sewage and reeover them (n
the air of the sewers, into which it was assumed that they entered by '
bursting of bubbles of gas rising from the sewage, from splashing of f«
ing sewage, or from the drying of the sewage left on the walb of ^^^
when the depth of flow^ dropped. Other experiments of the samt? Vifd^
were made about the same time by Dr. F. W. Andreweo, and wWl
corded in the report of the Me<lical Officer of the Local Oov«
Board for 1906-07.

Prof, C.-E. A. Winslow^ found in 1908, in an inveastigation for
Master Plumbers Association of Boston, that wliile the results of '
investigations of Horrocks and Andrewes were undoubtedly cot
qualitatively, the immber of bacteria tlirown off from sewage w«a«>^
tremely small that the local infection of the sewer air was i»f no impor
whatever. The general air of the house drains wa^ fotmd to )
free from bacterial life. Even neiu* the points where spla^^lm
there were only four times when intestinal bacteria were found, which I
Prof. Winslow to conclude that, so far as infection is concernedi J
air is not to be held responsible for the spread of infiTtioun dwwi»M-

It is the general opinion of enginci^rs today that when
system is well designed, carefully built, and prop<Tly tu m
sewage passes from the house© to thi* disposal worka or m
course which affords little opportunity for the HUh*

nr the occurrence of offensive putrefaction and fermentation.
IJiiforturiatcly accidenta occur tlii'ough the breaking of the crowns of pipe
i*cwer», the settlement of hea%^' raasonnt^ sewers, and other misfortunes,
which may cause sewage to collect in pools or at least to lose %felocity to
siirh an extent that more or less of the solids will settle to tlie invert.

1 i$. happens the sewer \s likely to eventualjy tiecome offensive.
1 s from thi» ihat the mairitenanirc of a sewerage system should

always be well provided frir, and those in charge of the work should
appreeiate the importance of investigating ever>' complaint which is made
rreiirding foul air from the system. These disturbances of the proper

'1 of the sewer network are generally considered m the only

ir retaining any longer the main traps on house connections,

which it 13 now believed by moat engineers are the main obstacle to the

♦ fErie^nt ventilation of sewers without recourse to the various devices

-upI f^xpeclients of an earlier date. In other words^ the recent improve-

!: I !it8 of sewerage systems, effected by a small expense for more complete

engineering planning and more rigid supervision of construction, have

fiaved a considerable ejcpense in ventilating appliances and a great deal

mce to property owners on account of disagreeable odors. Prof.

litated In 1909, in a letter read before the Boston Society of

CivH Eogineere:

** Willie we are right in spending money for plumbing which is free from

— "? defects, we are not as obviously justified in reconi men ding large

iditurea for refinements like back-ventilation and intercepting traps

,L>en the bouse and the sewer, The trapping of ordinary fixtures does

V with most, of the poasiVjle dangers of sewer gas. There are plenty of

*: ! H which will give a reasonable degree of security against siphonago

rhout back-vent ilatioii.*'

One of the best proofs that these conclusions are correct is the fact

%}mi the laborers engaged continually underground in the sewera of

l*:jri.s^ ttre kept under strict observation and there is no indication

>W,Mlever that their work in sew^er air baj3 any effect on their health.

There are a few authentic cases of loss of life in this country due to
«ewer air.* One of these is mentioned on page 562, and occurred near the
outlet of the Los Angeles outfall sewer. Another happened in a gate
chamber of the intercepting sewerage system in S^Tacuse and a third
impptined in 190^ in a dead end in San Francisco* In each case it is
f liable that the gases given off by the changes in the composition of
' H*wage, which are usually carried along within the sewage to a certain
' ' rtt, wtrre libcrat^Hl from the sewag*^ and colleote<l at the places where
XUq acGident*! oucurred. The actual composition of the gases i^s unknown »

«f i^vfi hmti n few ^lumn whift dftatb wm Appi^rmtiXy ilae to the nceumulaUon of
il»4 in MrT*«ni.

644 AMERICAS SEWERAGE PRACTICE

of eouree,' and the unfortunate inckkntB have no fuitiier beuing on the
queiftion of semer air than to indicate the desrabilitT of foDoviog the
practice of entering wellis when entering manholeB which have kng been
closed, and lowering a miner's light to the bottom of the manhole to be
certain that the air ij$ safe to breathe. Rare instances like these do more
pro\'e the poisonous quality of sewer air than does the oocasiooal suf-
focation of mell diggers pro\'e that the air in all the wefls used in audi
large numbers throughout the country is poisonous.

The movement of air in sewers is due to a number of causes, sooh tf
the difference in unit weight between the outer air and that in tbe sewers,
the difference in ele\'ation of the various openings between the sewers and
the external air, the flowing of the water through the sewers which tends
to move the air resting on the Uquid, and the effect of the wind on the
openings into the sewers, particulariy the outlets of large sewers.

Theoretically, the most effective openings for ventilation should be
those in the manhole covers. The connections through which sewage
and rain-water are delivered to the sewers from houses are likdy to be
filled from time to time by the discharges from those properties, while the
trafM xiaed on many street inlets and catch-basins, if they are in proper
condition, will l>e sealed by the water within them so that no air can enter
or escape there. As a result of this theoretical advantage of ventila-
tion through openings for that purpose alone, there is a tendency among
British engineers to connect specif ventilating pipes with the crown of
the «>wer8 and to carry these pipes up the walls of adjacent buildings.

The effect of the temperature inside and outside the sewers upon the
ventilation of the latter usually depends upon moderate differences
in temperature and the unit weights of air due to these temperatures,
although the difference may be large in winter. The tendency '^
the newer air is theoretically toward the end of the laterals, since they
are at a higher elevation than the trunk sewers and the warm sewer
air which is enrieavoring to escape during a considerable portion of the
year will naturally rise, while the colder outer air will enter at the lower
0fH.*nings of the M;w(jrs. Practically, however, it seems to be a fact that
the wind and the drag on the sewer air due to sewage flowing down
grade have some effe^'t at times in checking the upward motion of the
air.

While these views are theoretically sound, they were shown to be
of little practical imi)ortance by a ver>' thorough investigation made m
Leiccjster, England, in 1S9S-1K*. by the borough engineer, E. G. Mawbey.
Whffn he took charge of the sewerage system it was provided with
ventilated manholes and lampholes at the rate of about 37 to the mile

> AnulyncB of air in ventilated niAnhuIes in I^'ii«e»tcr. England, showed an tvtn^
i:i24 parts of CX)t per 10.000. and 21 parts in unventilated manholes, the Mtemal »»
haviiic 3.56. — "SMiitary EngiDeerini." Moore and Silcock. p. 393.

kBGULATORS, OVERFLOWS, TIDE GATES, ETC,

646

ooraplaints of foul odors were made and finally led to adopt-
policy of closing the manhole covers on ascertaining that odora
y came from them, and nmuing ventilating pipes up the ad-
building if permission to do this^ could be obtained, Thiii waa
ce with the practice of many other EngliBh cities. In order
how much circulation was really obtained through these
ale covers, Mr, Mawbey carried out many experiments. In a
J instance a 6 X 4 in. shaft was erected between Iw^o manholes
t apart. Anemometer tests showed that in both manholes the out-
rrents of air, after the shaft was erected, exceeded the inward cur-
ia the proportion of 69 to 20 in one case, and 41 to 19 in another.
Other case where a complaint was made of odors at a manhole at
itersection of two large sewers, two atncks of 9-in. stoneware pipe
erected side by side and the manhole cover left open. Anemom-
5st8 showed that the upward current of air with the double shaft
05,000 cu. ft* per day, and although it was only about 04 ft. dis-
Irom the manhole cover, there were upward currents through the
of 40,500 cu. ft. a day, while the inward currents were only
) cu, ft. per day. The cover was still a nuisance and was closed.
f similar experiments were made, which showed that the column of
. the manholes was too low to make the ventilation through then:
I a matter of any importance. This confirms the general American
}n that it is best to ventilate the sewers through the house con-
HiSg when the sewerage system is in good condition and there are
plumbing regulations which are enforced strictly.
^ authors have found that many complaints of offensive odors
Bowers have been due to the discharge into them of industrial
3, such as refuse from gas works. In one case, the trouble was
i to crude oil, wliich had escaped from the underground piping
orglng plant and percolated into the sewer through leaky joints*
ng hoiiae refuse Ss particularly offeiifeive, and if discharged into
ser having a sluggish current it may be the cause of foul odors*
f times objectionable odora are forced out of perforated covers
tnholes by steam discharged into the sewers. In fact, odors are
iikely to be given off from hot than from cold sewage.

:5RAPTER XVII

SEWAGE PUMPING STATIONS

In the design of sewerage works, it may be neccaaary to resort I
pumping where the sewage or storm water is collected at »o lo«^
elevation that discharge by gravity is impossible, as at; Wsiijhingtoii:!
reach a desirable purification site, as at Baltimore; to lift the sew*
from areas too low to drain into the main system by gravit>% or to fofflj
water into streams or tidal inlets receiving sewage, which would bcco
offensive unless flushed in this way.

Whether the sewage shall l^e lifted at one or more points is usually J
matter to be settled by comparing the fixed and operating expeiiscs (
different plans. The operating expense of raising all of the scwa^ i
one point is less than tliat of doing this at two or more points. On i
other hand, if all of the sewers are made to drain by gravity' toonei^lftfli
their cost may be greatly increased on account of the deep cuts and bu
cross-sections necessarj^ in order to obtain satisfactorj" velocities of fio
Various projects must often be considered^ both with and witho
pumping, and the extra cost necessary to drain to one point, togc
with the cost and the capitahzed annmd chargers for operation
depreciation of the pumping station, must be compared with ainiil
charges for a project with two or more stations. Conditions may e\1
arise where^ if the 24-hour flow can be handled by working tbe statiool
its most economical rate for S hours, the reduction in labor charges '
complished in this way will warrant the construction of reser^'oin* ^
store the sewage when the pumps are not running. The tnink sewi
of combined s>^stems sometimes have such a large capacit>' that ih
alTord considerable storage capacity during dry weather.

Comparison of Different Designs.^ — This matter of the nsUt^
economy of different designs is not so simple as it appeiu-s at I
thought, but involves a mmiber of factors. Prof* Geo* F. Swain ^i*
in the * 'Journal of the New England Water Worka Asaociatiofl
voL ii, p. 32, the following as the correct manner in which to ati»^k I
subject:

**The problem, in its most general form, may be considered to he iHi^^
certain structure or mflchine costs A dollars^ it reqaires the t*x\
B dollars for rcptiirs ut interx^ttls i>f a years, it will hiSt for n yc4iT>
worn out it may be sold for D dollars. A sec»»nd structure or i
accomplishing the same object costs At dollar? fM-rtir^^ h.i. ^^^

040

SEWAC

f AT IONS

illars for repairs every *i yearn, lftst« for rii years, and is worth Dt

when worn outt Which of these will he more ecunumical, as a

ermanent thing, the rate of interest being r, payable »cmi*iinniially?

**To answer this question we must compute the amount of present capitat

sufficient to provide permanently for each of these struetures, and the one

rhich requires the smaller capital will be more economical* Or we are

nabled to find, by the same method, what tlie cost At nf a (perhaps new)

nee must be, in order that it may be more economical than a similar

iliance in use, under various suppositions as to the life^ cost of main ten-

anee, ete.

*'The pre«i»nt capital required for any atnicturc will bo made up of three

'*Firat, At the cost of the structure,

*' Second, a sum which, put at interest at r per cent., will Increase in •
s, by the amount B, This sum may easily be shown to be

B

I(H-0.5r)''- 1]

* being ejqjressed aa a proper fraction (6/ MX) if the rate is 6 per cent.).
"Third, a sum which, put at interest at r per cent,, will amount, in n years,
it8<?lf plus {A-D); aince at the expiration of the n years, the worn-out
•fjucture being sold for D dollars, there will restilt a sum sulfieient to again
Expend A for a new structure, and have the original sum remaining, which
I another n years will amfjunt toauthcient to purchase a third structure, and
I un indefinitely. This svim is

A-D
[(l + 0.6r)*"- 1]

** The total present capita.1 involved in the use of any structure is therefore

1(1 H- 0.6f)»- - 1] ^ 1(1 -h 0.5r)»* - 1]

*'In certain cases the fonnula is simplified. Thus if D is so small as to be
practically zero in comparirttui with the first cost of a new structure, and if B
I the uniform annual cost of maint4^nance (supposed payable semi-annually)
in the case of a pumping engine, we have

B

c = .4 4- : +

r " [(l + O.Sr)*"- 1]

which A is the first cost of the struct lire or machine, and B/r is the
lixed cost of maintenance, Tliis result shows that it is not strictly
3rreet, in comparing, as a permanent investment, let us say, two pumping
I which may be supposed of equal durability, to compare sin>ply the
cost plus the capitalited cost of operation, since this omits the last
erm in the above formula. This term, however, when n becomes large,
Apidly decreases, and in many easels may well be neglected/*

STORAGE AND SCREENING

In most sewage piimping stations there is provision for some storage
the sewage, in order to equalize the fluctuations in the rate of flow

SEWAGE PUMPING STATIONS

649

ilich are given off during storage; illumiaating gm has been known to
ftpe into sewerage systems, and of lat-e gasoline entering the sewera
has become volatilized and caused some explosions.
the few comparatively large sewage regulating bajsins in this
iiitry waa built in 1S99 at Concord, Mass., from the plants of one of
authors. Its purpose was to store the flow of the sewage during
hours when an electric lighting plant operated in conjunction with the
sewage pumping Btatioii was carrying its heaviest load, and to give
totter distribution upon sand filter beds located at the end of a long
(t^iron force main. This well has an internal diameter of 57 ft. and a
ge capacity of 222,000 gal. It has brick walLs from 20 to 24 in.
ck, An inverted parabolic groined arch bottom of concrete, and an
' oined arch roof of concrete, with 24*in, brick piers 14 ft. 9 in.
The construction of this well w^as extreme^' difficult and
described in the "Journal" of the Association of Engineering
ies, May, 1900.
knother reservoir of the same type was built in Clinton, Mass., by
the Metropolitan Water Board in 1898. It hns an inside diameter of
) ft. and a height of about 13 ft. The roof is supported by concrete
i arches and brick piers 14.57 ft. apart on centers. The side walls
\ ft. thick at the top and 3 ft. 6 in. thick at the bottom. The bottom
1 roof each have a minimum tliickneas of 12 in. The trunk sewer from
I city terminates in a screen chamber betw^een this reservoir and the
iping station, which are close together, and the sewage can be
kI into the reservoir and given an opportunity for a large amount of
f ion or it can be sent directly to the wet well from which the
ion runs.
iof h these structures have groined roofs, a form of con^struction which
[ic4ipable of satisfactory mathematical analysis, although it has
useil for so many j'ears that practical ex]>erience has shown that
ifTal dimensions can be employed safely. A discussion of
is of desigtiing such roofs, by Thonuis H, Wiggin, was
Bted in Eng, Ne%Vff, April 7, 1910, and as the different methods are
Dpirical none of them should he used without a study of this article,
uh thrir limitations are pointed out and important data concerning
ined arch roofs are tabulated.

Thiire have beeu a number of failures of groined arch roofs in the

States, and a lack of confidence in them is felt at the present

f ( 1 9 1 4 ) by some en gi neera. T hey hav o certain advan tages , ho we v er,

tvh the flc?<igner should carefully oonsider before atlopting another

of comitruction. In the first* place, their first cost is usually no

^t«?r than tluit of reinforced concrete stab roofs, ub is pointed out in

in the article by Mr» Wiggin to which reference has been made.

he itecoud jilace they are free from steel, either exposed or encloaed

^A

650

AMERICAN SEWERAGE PRACTICE

in concrete. This is an advantage, although It id difficult to give it nay
definite value. In the winter the sewage may be considerably wamcr
than the outside air, and it is entirely possible that the roof and wall* of
the roser\^oir at such a time will be reeking with moisture. Ordinar)'
moisture is injurious to steel and it seems probable that the moisture in ft
sewage reservoir may prove still more destructive. Experience \^
indicated in Boston, for instance, that under certain conditions tl»A
metal in sewage wells is liable to become seriously corroded. Such
experience has been observed elsewhere, but observations are so di^
cordant that the only safe deduction from them is that the atmosph*^
in a sewage roserv^oir is likely to be partioularly severe in its actioti ^^
steel, which makes the use of I-beams and reinforced conoreto unus^i^^V
expensive on account of the necessitj'- of using exceptionally l^^**
amounts of metal.

Except in small plants, provision is usually made for screening, ^^^
sometimes for sedimentation, of the sewage before it reaches tlic pui«^"*^
There is no uniformit>' of opinion among engineers regarding the si^-^*"
screens, either as to size of bars or size of openings. In fact where **^^^*
age comes from an industrial district where rags and waste arc lil^^^-'
to be thrown into it in lai^e quantities, some engineers believe that ^^^ *
less expensive in the end to install a relatively largo automatic^^^J^
controlled pump which can successfully hiindle unscreened sewage t^W^
to use a smaller pump which makers screening a necessity, as such scifctSi-S****
ing involves much more or less continuous labor charges. Expcfi«^-'=^^
seems to indicate that such sewage may be handled without screenin^^^ '^^
pumps 8 in. or larger in size and that smaller pumps are likely
become clogged more or less frequently, the trouble increasing ttB
size b reduced.!

The screen chamber of the Old Harbor Point pumping plant of
main drainage system of Boston, which was ofhciallj^ put in service
Jan. 1, 1884, is a structure independent of the pumping station. 1
25 X 32 ft. in plan, inside measurement, and the 10-1/2-ft. main se'
terminates at one of its end walls. There are tw^o channels in the bot
of the chamber, leading from the inlet to openings in a tranm^erfie
each oi>ening being closed by a 7 X 6-1/2-ft. sluice gate. On the k-w*^ "
the opening in the wall there is a screen cage, 7 ft. H in. high, 7 "^ '*

in. wide, and 3 ft. 4-1/4 in. decp» with the back^ sides and \4jp :

3/4-iii. round iron rods with I4n. spaces between them.

* Ttic opinion i« •oinetlines held thjit oq aecouiit of its op^n ptuma^g^ »»«}
v»lvQi m eomtrifiMtttl pump mil b»ndlc »nytijinjf wbich will tta«* Ibrmiieb tb» •
Thtfl in not timverBAlly true. ExpKsrictice with tb».'
that. cTPiton wudtc enU«rina tb«» *»r«i«»rH fmrn lttr«<» >-
jiipt? iind* v^hf^n ►^^ ""' J^.. .^,. w. u. ...,..«,« ih. .<;
plnrtwl at the (n;
»nri the Mt^ugc. v
Ai if Um leivAjp-* ptLoaeci ttiroujtii a sump.

SEWAGE PUMPING STATfONS

661

Boimtcrbalanced and raised or lowered hy small steam engines. Bat^k of
Ihis tram?vert^c partition Ls another, also provided with two openings with
reen cagcn, Imt without sluice, gates. There is a longitudinal central
»rall running from the rear end wall of the Imilding and intersecting botfi
ransverse walls, so that m plan there arc four screen pits and a main
Ktrance pit. The screens were made in the form of cages in tho belief
Ihat they would retain tlve solids while they were lifted to be cleaned,
thus making that operation easier, it was hoped, than cleaning an in-
clined or vertical rack.

Recent designs for a sewage piunping station in Boston have called for
inclined racks making an angle of about 30 deg. with the vertical, and the
iesigner, C, II. Dodd^ informed the authors that he would use a still
itter slope when practicable on account of the greater ease in raking the
reens. Where vertical screens are used, some engineers attach a
horizontal ledge or trough to their bottoms to catch any material which
Ciiay drop from the bars when the screens are raised.
The screens used in the Boston Metropohtan sewerage plants are
ges formed of iron frames 8 ft. 3 in. high, 5 ft. 4 in, wide, and 2 ft.
^11 in. deep, hekl in position by guides. The front of the cage is open.
The back and two ends are double rows, staggered, of 3/4-in. roda
spaced 1-3/4 in. on centers. They are raised and lowered by double
drum steam hoisting engines.

The .sewage pumping station built in Detroit in 1912 has an indepen-

^dent screen chamber on the 9-ft. sewer rumiing to the main buikiing.

It is nearly circuhu* in plan, the deviation from a circle being due to a

Battening of the w^alls so as to produce straight sides where the pairs of

ereen guides are located. There are two sets of screens, one 3 ft. be-

|hind the other, and the chamber is 15 ft. wide where they are located.

Kach screen is 10 ft. high and 7-1/2 ft, wide, with 2 X 2-in. bars 2 in.

fcptwt. The bottom of the screen has a horizontal shelf to catch trash.

The center guide for the screens is a pair of channels placed back to

ck, and the side guides are made of Z !)ars wnth one leg imbedded in

the concrete wall. The screens are counterbalanced and raised by hand.

The exterior of this chamber is shown in Fig. 323.

Special provisioTi for sedimentation is rare where centrifugal pumps

re iLsed, but an unusually good example of it is afforded by the chamber

[l>uilt for that purpose at the sewage pumping station in Washington, ill us-

traled in Fig. 321.

At the Colombes pumping station of the Pans sewerage system, the

itial (1894) equipment, which consists of reciprocating pumps, had a

oIaI capacity of 31.700 gal. per minute, and to prevent injury to their

^ator ends a settling basin of 3229 sq. ft. area has been constructed. It

vas described as follows by Bechmann and Launay in the " Annales des

Pcmtit ct Chaus8<5es," 1897.

652

AMERICAN SEWERAGE PRACTICE

**The sewage is discharged into the basin to free it from foreljpi 1
sand and f^cnae. At the inlpt^ which ia in direct connection "with the (
fall »€!wcr (Aqueduc d'Acheres), there is a screen of 128 bars 0.158 in. Ih
making an angle of 22 deg. with the vertical and 0,8 in. iLpari, centisr j
center. Between alternate pairs of bara move the teeth of eight i
which have a uniform speed of 3.9 in. per second aruund the externa
of the rack. The t-eeth of these rakes, guthering the refuse, remain ha
up to the moment of unlatching, whicVi occurs automaticaUy when i
roller cams escape from their guidea. The rakes are moved by t*ekle i
by a 1-h.p. electric motor.

"Immediately tiehind the rack is the bjisin. It b rectanguUr, 98.4 |
long, 32.8 ft. wide, with its floor about 4.9 ft. below the invert of the i
at the inlet. It has a concrete bottom and masonry^ walls, and uU surfj*
with which the sewage comes in contact were given a ooat of Por
cement plaster. On the aides and lower end of the basin there are wrii
with flash hoard regulation, which enable the discharge to be adju
correspond with the rate of pumping. The checking of velucity du
great length of the weirs, 213 ft., and the large capacity of the basin i
the precipitation of the solid matter.

"To remove this solid matter, composed for the most part of or^th
substances, in a continuous manner a ver>^ aatisfactonk* de%-ice (p
a clamshell bucket) is employed- It is construct^l of two balf-eyltn
steel plate^ able to oscillate about a common shafts provided aJoiig tli
sides and ends with teeth which cross each other at the time of cln
apparatus. CrankSt shafts, chains and latches are providr '
ically opening and closing the apparatus. The device hit!
cubic yard. It is mounted on a timber frame moved by
Tlie dredged nmteriul ia placed in small cars, which are etii]
railway on which the material is moved, whence the farmers remove HI
fast as it is delivore<l/*

The subject of screening as a method of sewage trealmenl b db'
cussed in detail in Volume III. "

PXJMPS

Tho equipment of a pumping station must be selected with m i
meeting the usnsl working conditions in the most economical i
which the funds available for the plant permit, and also to tnoetia]jC t
maximum conditions with such a degree of efTi
by the frequency of their occurrence. A great i
purchaser of a pumping plant which will operate with the high
ficiency only when subject to its v^jy iafrotiuent laaximuiw ciomlir
something approaching them. The late Charles A. Haicuc; montioatf t
case of this sort in his "Pumping Engines for Water Works:"

**The engines advertised for were proportioned, accordin:' ♦
fications, to pump against a head 5f) per cent, grenter than re ^
regular service^ with the result that triple expan^on cagi^ica w*jre j

SEWAGE PUMPING STATIONS

653

conditions where compound engines with smaller ste^im ends would
ive ufidoubtedly done much more eeonomic work. What happened,
|iparenti>% was that the high and intermediate pressure cylinders did so
luch of the work that there was only a low-temperature fog left for the low-
ure cylinder to handle, and the third plunder was largely operated
rtttigh the medium of the crank and connecting rod, dragging the low-
feasurc piaton along if iciden tally,"

Iq the selection of pumping plants for sewerage work the primary
insideratioa should be reliability of service. This meatia not on]y
Mrdy construction but also, in the case of electrically operated pumps,
iUabiUty of soiu-ces of current. First cost should never be considered
itself, but only in connection with operating charges, for the totid of
ie annual fixed, operating and depreciation charges is the item to be
idiod. Floor space must sometimes be regarded as important, and
LH frequently the desirability of having the water end at low levels, of
iarting and stopping the pumps automatically, or of combining the
vw&ge pumping plant with a refuse incinerator, after the system occa-

Uy used in England, or a lighting station, as at Concord, Miiss.
In estimating costn, it is desirable to obtain actual operating costs
Dm places using plants like those under consideration. It is inevitable
manufacturers to state the steam or current consumption of their
kimpB as small as they consider it safe to place them, while the engineer
\ust be more liberal If the capacity of a plant is made close to the
ErtiLal needs and then it is bought under a guarantee of performance,
y failiu*e to equal that performance can rarely be made good liy a
eduction from the contract price; the plant w^ill not perform its service
it should, thus perhaps throttUng the sewer system, and the engineer
a failed to properly safeguard his client* This is particuhirly impor-
int in t«>nnectif>n with centrifugid pumps, for experience has shown
any times that their capacity has not equalled that contemplated
the plans. It is often false economy to curtail the cost of a project
r paring down the size of a pimiping plant.

The engineer must also be very cautioujs about using the information
Igarding the cost of sewage pumping given in annual municipid re-
l>rtw, for very often the pumpage is actually unknown and the quantity
rported merely a guess* The pumps run under operating conditions
lich would not exist in stations of more modern design, and the charges
attending to screening are lumped with those for running the pumps,
bich may cause cou&iderable error if the conditions are like those at
run, at one time, where the cost of keeping the screens clear Is reported
have hi tor than the cost of pumping.

In com I Jttts financially the fu*st cost of the complete plant

each type and size should first be estimated, from which the annual

tifd charges cim be ascertained. Then the operating and depreciation

for the present steady load should be estimated, and also those

^ra,

for the extra loads and for the steady load some years lat<>r. in «iitt8
plant.H Biit'h estimates generally indicate, in eonneetion with local con*
dittons and the engineer's opinions regarding reliability, that the cho^*^*^
vril! be between a few sizes of one type, which should then be sttuditHl*^
detail,

lo this connection it should he pointed out that sometimes the c^^
stmction of a small piunping plant for txjniporary serv^ice \& prefer J**'^^*'
*to the immediate construction of an expenaive sewer too Urge for s^^^
use that will be made of it for a number of years. This was sIjowT^- '^^
Newton, Mas^., where a station costing S6700 and designed for a tj*^^^^^"
service of only 10 years, was S500 a yeiir cheaper for that period t^^*^
the fixed charges on the alternative, a sewer costing $45,000.

The relations between the reservoir, pumping and force main cap.^^*^
ties were stated as follows by Frank A. Barbour, in a discussion on :iix^E^^'
pumping plants for sewage, before the Boston Society of Ci\nJ Engin
Jan. 9, 1907:

"The more nearly coutimiously a puntping plant can be maile to ojii']
at a uniform rate, the more economical is tiie result, provide*! thit b
account does not offset the Having in a decreased storage capacity, les»ei
Biae of force main and retlnced friction head thus made poa8il»le» Wit."
steam plant a resjcrvior large eaougli to hold the sw^wage during the hour9
punips are not running and a force main adapted to the pump rule
required. If the amount of sewage to be handled could be aecxirat-
predicted and a pumping unit equal to the average daily discharge mlopt :
then a reservoir only large enough to equalize the hourly variation would -
necessary. This cannot practically be done and the neare-st approach
uniform discharge is obtained by dividing the plant into such a numlM»r-
units as will most nearly approjtimate in their capacity the rate o'
in other words, by dividing the total power into uuits bcvit capable ot I
the load curve. With such an arrangement, the re:§€rvoir ciui hts reduccd^^ — ^ '
a size only sufficient to prevent too frequent starting and stopping of W^ ^
units, and the force main can be designed upon the basis of the maximi^ ^"*
rate of inflow for the period in the future which it is economical to coniiii
This continuous discharge is often extremely desirable in drsptjsal wor
where either purification is effected or the sewagp dispoHod of by diluUoi

As a general proposition in designing pumping stations, it b advisA^^-^'*
to determine m accurately as jjossible the work required constantly ft^ *""
the first day of operation, then eiitimate the additiaual load wl « ' -'^

arise from time to time on account of emergencies for which ]*' "fl

must be made in the original installation, and finally estimate the rt<pi"=^*^'''^

zkt.

ments for such future time as seems desiralde. In this way the *'
will be able to adopt units of such siise that one or more of therj*
handling the ordinary load with good ei*ononi^
ness to meet emergencies will be restrict*^d t,
equipment for the purpose and will not Iv

^ '^^-

SEVfAGE PUMPING STATIONS

655

> operating equipment of large capacity under loads which make its per-
ormance highly wasteful.^

The selection of the pumping equipment should be governed by a

z;ard for operating and maintenance charges and faeility in making
probable exteniiions in tlie future, as well as by first cost. The time

eui in analyzing the need.^ and the methods of meeting them should

ever be skimped, for if a pumping station is required il is particularly

Jesirable for it to be a good one, because iU reconstruction without

aterfering with service w^ill be troublesome and if its operatiou is unsat-

sfactory the whole sewerage system is burdened with a defect. The

ition IS not an isolated detail, but an integral part of the aystem,>

It ifl not neeesi^ary in this place to go iiito the details of the design of
pum]>s^ or the arrangement of steam plant, as these specialties reqiure a
irge amount of space for thorough treatment, and are well covered in a
BUinber of books. The following notes are intended merely as a schedule

the points to be considered in workmg up the outline of a pumping
;)lant, and as a guide to the steps to be taken in making a final selection of
be equipment.

RECrPROCATmG PUMPS

Most reciproeating pumps used in pumping sewage are driven by
X, although the triplex t>^pe, which is well adapted for this serv^ice,

•'An early Ulu^trtition oi this priiiciple will tx* found in the pumpitig station of tho Bostfin

trwemgc sy^tt^in, which ia expliiin<?tl in the report by Etiut C, Claj-ke (188dJ a« follnwfir ** Ab

ho ciiy w^weri receive rain'Wftt«r, and as it is deair^d tt> take fts much of this na pooaitilc^

capeoiHUy frurn certain districta. it fuHows that duriniE short pericKli of time, whoti it rnini,

wry much greatur pumping capucity is iic3ed<»d tkao b usuatly euffldcnt. There must»

b^rpforv, be a pump, or pump«, to nm coatinuoualy, and oiher» to run only when it rain*

f Ibawv. The chief item of expense in pumping i« the coat of f ueL For tfae *iike of economy

*lhe pumping engines for continuous service must do their work with txB little consumption

of tuel IM poMlble, and to aceompliah this an cxpenBive machine can be nfforded. For tho

I which run only occAflionally cheaper machineft arc more economical, the saving in

I on the fifat coat mor^ than compeoaatiog for the eitr]^ fuel coEkSumed by them.

I piunp'ing plant of the Boston mnin drainage worka includes two ex|K*fiflive high-duty

mud two cheaper lowcr-tloty onginM. The high-duty engines were designed by

LoAvitt, Jr., on general specifioatiooa prepared by the city eagii^er, Mr. Davia.

thvy were built by the Quintanl Iron Workji, of New York, and coat about 1115,000 each;

iBomiOat capacity 25.1XJ0,0tJ0 gfil. each* Tho two pumping engine* for atorm aervio© wore

■ built by the firm of IJenry K. Wnrthington from their own deaigna and cost $45,Df)Q each.

iThey Are of the duplex, cc*mp<iuud, CMndcniing type/' The Urger engines deveIofj«td

jl22.00f».fKX» and 125.000,000 ft -ib. jK^r UXJ lb. of coal on trial, white the Worthington enginea

[were guaranteed tt» deliver 60,0(30, «»no ft.-lb.

» A deuile<l explanation of the methods followed ia aelecting the moat economical moti^-e
ower for pumping sewage at Lynn, Maaa.* in given in Engineering and Contraetingi
Jan. 7. 19 H, by Frank H. Carter

« For information regarding large ateam-driven pumpa. the reader ia referred to C. A
IHague's "Pumping Engines for Water Worlu," for a description of all typea of pumpa to
IjProf. A- M, Greene's ** Pumping Machinery/' for centrifugal pumpa in p«rtieular to Frit*
iNeumnDo'a **Die Zentrilugalpunipen** (Berlin. Juliua Springer) and C. G. de Lttva!';^
"Centrifugal Pumping Machinery/' and for the deaign of ateam plant to ** Steam Power
' by Uettiy C. Meyer, Jr.

650

AMERICA]^ SEWERAGE PRACTICE

is as well suited for electric motor or gas-engine operation as for i
operation. The smaller triplex pumps for sewage are iLsiially provicli
with hall valves arul the larger sizes with leather-faced clack viUves.
a matter of fact, a power pump driven by a direct-connected motor i
engine or through the metlium of a noiselesa chain or even a belt may I
the best equipment for certain conditions. The pump can be locat
at a lower level than the engine, if dcsiral>lei and the economy of mn
of the small steam and internal combustion engines now available 1
much greater than that of direct-acting pumps of all but the larger sia
with so-called triple expansion.*

Types, — -There are two tj'pes of steam pumps, the direct-acting ad
the fl3n;^^heel. In the direet^acting type the gtteam cjdinder is in lili
with the water cylinder operated by it and there is no flywheel to i
up and give out energy. In the flyw^heel type the essential feature ia|
revolving flywheel which equalizes the angular motion of the shaft
which it is mounted and thus carries the engine past the dead et*nt
at the ends of the strokes: in most fly svhccl pumps the plungers are drive
by rigid connections with the steam piston rods^ and the crank shaft an
its flywheel are driven by a connecting rod or rods from the crossho
of the ongino.

The direct-acting pump, having no flywheel and operating against t
inert load, must take steam for the full length of the stroke in most case
and there is no expansion in the ordinary sense of this term. At
end of the stroke, the steam valve is thrown in a variety of way»» m
pump maker having a special t>i>e of gear for the ptirpoac, and st
pressure is admitti^d to the other side of the piston. In a 8oc;alleil con
pound direct-acting pump the exhaust from the high-pressure r>dintb
goes into a low-pressiu'e cylinder for similar use throughout the who
stroke, and in the so-called triple-expansion dire^Jt-aeting pmnp.
exhaust from the intermediate cylinder goes into the low-prcssiu
cyhnder for a full stroke. In this last t>*pe the total expansion of th
steam is rarely over seven or eight times, much less than the cxpaiisi*Jfl
in a fl>^^heel pump with a steam end operated like a standard engia*
for power sendee. As a result of the small number of expansions poeit*
ble in a compound or triple direct-acting jiump, it is unnec
use as high a ste^un pressure with it as is de.nirable with a conipoi
triple-expansion flywheel pump. On the other hand, good condon
and steam jacketing are held by most designers to be particularly w^^
with the larger direct-acting pumps.

The duplex liireet-aeting pump eoasists of two eompleto pumjiei ml

'"A* to pum{i»dri%'«ij by n bt^U ' ^'" ' ' * ' '

nittitt uadotjbtciily udvf for *i

,||rem.r MV»n.r., ..f H.. . ,r . I . r, nry ty p.. , :.:...-. ^„ _

etfi viiig ll<»* fjiimji* by jcmHtis r*Uwir tlmn by i

Rey Cir., VOL lU, p. CU4.

7E PUMPTJ

mde, with the iimiii steam valve of each operated by a connection
"om the Rrosshead or an equivalent reciprocating part of the other,
ich a pump is remarkably aelf-contained and oan be manufactured of
design and materials at such a low price that it soon became the
ing t\'pe for moat purposes where moderate quantities of water had
be handled. Since the great improvement in centrifugal pumps its
sld has been somewhat curtailed, but its reliabihty, demonstrated by
ny years of v^aried service^ makes its consideration necessary in select-
ing the equipment for a great range of serN'ice.
^^ The duty of such pumps in water-works service is usually guaranteed
^^t about 60,000,000 ft.-lh, per 1000 lb» of dry steam for compound con-
I^Klensing and 90,000,000 ft,-lb. for triple condensing units. Small sizes
i^Kriil not show an^'thing like such duties in operation, however, the
B^nge being from 10,0fJO,0O0 to 40,000,000 ft.-lb. or from 198 to 50 Ih.
B> of dry steam per actual horse^power per hour, depending on the size,
; operating condition, and ratio of load to capacity*
I High-duty attachments can be added to large enginea of this t>T)e,

which will make them much more economical, but they are hardly
refjuired in sewage pumping work.
^ Where the capacity of the pump is from 3,000,000 to 5,000,000 gal. a
^Hay and high duty is required, a compound dyn'heel pump has ad van-
^tage^s wliich must be considered. This type has steam cylinders with
cutoff valves, and its simplest form is a horizontal cross-compound
igine with a pump cylinder tandem to each steam cyl inder. The Holly-
askill pump much used in water- works ser\nce is a more elaborate form
nsLiting of two compound engines connected to the same crank shaft,
id a pair of water cj^linders with double-acting plungers. The Snow
mpourid pump is a later and less complicated type, and while it uccu-
fics more space than the Gaskill its parts are more accessible and the
wer is transmitted more directly.

The guaranteed duties of horizontal compound condensing flywheel
pumps are usually from 110,000,000 to 130,000,000 ft.-lb. per 1,000 lbs,
of dry steam.

Horizontal flywheel pumps have occasionally been buOt for triple
^escpansiout but the large floor space they occupy in comparison with ver-
Ktical pumping engines usually renders them less desirable than other
' t>T>e3.

^^ Vertical pumping enginea usually follow the general design worked out
^■rst by Edwin and Irving H. Reynolds. These are usually triple-
^^■MpHioii^ and as inquirv^ is often made why a compound condensing
^^PSfiiiltd m not more often UBed, the following statement of the reason
; is reproduced here from a paper read before the International Engineer-

E Congress of 1904 by Irving H. Reynolds {Tram, Am* Soc. C* E., vol.
d. p. 519).
L

Valves clused.

Valves open*
Fu!. :i01. — Valve deck, Baltimore tiewjige pumps.

G58

AMERICAN SEWERAGE FRACTWE

*' It has been argued that with the low steam pressure often used, a com-
pound engine would give pmcticaUy the same economy ns the triple and nt
much lcs« ftrst cost. While this is to some extent true, the fact is «»vef*
looked that economy is not the sole reason for the adoption of the triple,
but that the general excellence of the triplex pump tor handlitig water and
the adaptability and flexibility of the machine jus a whole are the factors
which are r<*spon«ible for ita wide popularity. Having dete^rmined or*
three single-acting purapa as the best and simplest form, it is CMsenlial. iti
order to drive them direct, t^J have tliree steam cylinders, and thus there is
obtained the triple-expansion engine, practically without increased cost and
with a steam economy from 10 to 20 per cent, higher than that of a Cumpound
engine working under similar conditions,"

The guaranteed duties for triplo-cxpansion pumping engines varj'
from about 140,000,000 ft.-lb, per 1000 lb, of steam for small units and
moderate steam pressures to 160,000^000 ft.-lb. for large engiues and
steam pressures ofl50tol751b.

Piston Speed. — There is considerable discussion at present reKarditiK
the proper piston speed of these large engines. In Mr, Reynolds'
paper, already quoted, it is stated that speeds higher than 200 to 250 ft,
per minute probably offer no advantage, because the small clearances
of the slow-speed engine enable it to show as high economy as the high-
speed engine, despite the theoretical advantages of the latter. Furthrr*
more, with high speed, the cost of the water end is, if anj^hing, incrt!Sised,
for as the time allowed for the seuting of the valves is less, more aie*
must be provided, and to avoid friction losses all porta and pxise^age^
must be maintained fullj^ as large aa on slow-speed pumps. In the ilis-
cussion of the paper, C. G. de Laval presented the argument for piston
speeds higher than 200 ft. snbstanlially as follows: When water is tjan*
in motion it is not a question of speed in feet f>er minute, but of changes
of plunger or rotative speed, and these changes do not affect any other
part of the pump end except passages and valve-s, which always should
be made amply large to allow a low velocity tlirough them,' The high
speed allows smaller moving parts^ which are less cumljersome, more
flexible and easier to handle than the large parUi of slow-speed euginei,
and wUl also insure easier making and stronger shapes with less metal
than can fte found in slow*8peed engines.

Water Ends,^ — There are two distinct tj^pcs of water ends for pmnpF.
the piston and the plunger. In the piston type, the waUyx c}
bos a cylindrical barrel throughout the distance traverseti by the p
which is fitted with flax packing or metal rings so as to allow a.
leakage as possible between it and the wali-
tisually has a brass lining to reduce the fri'

A A vdocity fmtn 3 to 3-1/2 ft. per Mk^^ond thrmiftH vaIvh e>pomnc« ta ujtiftlty rtnuiixirM
^Mt In Urco immpinc vnginca.

Valves closed.

Vjvlvr« npt*.Xi.
[)i — V'ilvi' deck^ Baltimore sewage puinpt;.

SEWAGE FUMPINCf STATION.s

659

tij^htnc^* In the plunger type, the plunger does not touch the walls of
the cvUnders^ but parses through a stufEng-box or packing ring which
prevents leakage* Its action is not that of a ptBton, forcing through a
cylinder all the liquid in front of it out to the cylinder wall^ but it dis-
places in the chamber into which it is forced an amount of liquid equal to
that part of its vol inn e which is thrust into the chamber, whence it
derives its name of plunger. It is much less expensive to keep the
water end of a plunger pump in good condition, pskrticularly when
aping gritt>^ liquids, than that of a piston pump, and consequently
|U3 type should generally be used for sewage, and special attention
[>uld be paid to the position and arrangement uf the stuflfing-hoxes,
they will probably need more attention in a sewage pump than in
handling water.
[There are two types of valves in general use in pumps, the disk and
the clack. The disk valve is usually of rulibor or rubber composi-
pn^ although leather was formerly much employed. It is not often
[it they are more than 4 J in* in diameter. They are usually held down
on their seats by helical springs. If a valve deck will not furnish
urn for a sufficient number of seats, it is perforated with large orificefl
which hexagonal or octagonal boxes are attached. These boxes
itly increase the area to which the disk valves can be attached.
[Clack valves, which are generally used in sewage pumps, are flaps
tier actually hinged or attached to the valve deck so as to move as if
By were hinged. In the latter cjise they are strips of rubber 5/8 to
Fin, thick, usually with a metal disk on the lower aide somewhat smaller
than the tipeniug in the vaJve j»eat and a heavier arid larger disk on the

Bp to add weight. Clack valves frequently cause much trouble iKJCause
cks and rags are cauglit on their stoats and hold tht^m open.
Ball valves are also used to some extent. In English pumps, the clack
jplvcs are sometimes made of very thick leather, such tvs that from the
H|)popotaraus and rhinoceros. Hinged clacks are more often used now
^ban the simple flap pattern; they have a leather or rubber disk held
^fctween metal plates, the top plate having an arm running sideways
to a hinge connection with the valve seat. The valve deck and valves

tthe Baltimore sewerage pumps, built by the Bethlehem Steel Co.,
I described briefly later in this cha.pter, are illustrated in Fig, 301,
large clack valves arc likely to cause pounding, they are some-
es provided with a small clack valve on their upper surfaces.
They should only be used with pumps of slow and moderate speeds,
as they are sluggish in action.

Tlie t^lack valves of the Leavitt pumps of the Boston main drainage
works, built in 1884, are rubber, and great difficult)^ has been experienced
with them, due hirgely to the brejiking of the rubber where it acts as a
hinge. In the Ward St* station of the Bosten Metropolitan system

660

AMERICAN SEWERAGE PRACTICE

the Vfdves sltq hinged and swings ou a manganese brouse liingis bdt;
they have rubber ^htid canvas seats which are bolted to brass platen.

The English views regarding reciprocating sewerage pumpa are
stated as follows in M, Powis Bale's **rum{>8 and Pumping/'

**If sewage or shidgc is pumped by steam, a long-stroke plunger pump ia
generally tu be preferred to a piston pump for this duty, but many large
single-acting lift pumps are also in use. It la important for the liquid lo
have as few reversals of its flow aa possible, and that there be no eorapli-
cations in the passages or comers where solids can accumulate. The valves
should he as large and free as possible, and readily examined; eoraetimes
for this work the valve seats are made movable aa well aa the v«J^
Wrought-iron clack valves with leather seats are used for sewage pur
and also double-beat vtdvea. Sewnge lift pumps are often made of cwsC
iron, with leather buckets and valves, the clucks of leather weighted with
iron plates/*

The above statement regarding the reversals of flow and absenco of
pockets to collect sludge, is particularly important in connection with
sewage pumping. It is true that an}' checking of velocity in a i)tiiDp
chamber will occur for such a short period that there is little opportuni
for sludge to settle from sewage, but the less chanoe there is of this
smaller the probability^ of clogging in passages and the accumulation of
leathery coats on the valve decks. On this account the pump details
for handling sewage should be more open and direct than arc dcmie-
times considered necessary where clear water is handled; pumps of
different makes are unlike in thc^e details and as it is unwise to go to
the expense of a special design for a small sewage pump, the diffrrent
details of standard commercial pumps should be 8€rutinize4 oarefulb^n
to ascertain which are the most suitable for sewage. ^^M

Connections.^The following suggestions regarding the connectionfl
of reciprocating pumps were issued by the Snow Pump Works.

"Faulty connections are gen^a% the cause of the improper action ni a
pump^ and great care should, therefore, be taken to have everytliing right
before starting. To accomplish this, note carefully and undemtaAd
thoroughly the followinj^;

"Be sure that tht^ quantity of water you desire to pump is available and
that your pump is within easy rerich i>f it when it is at it« lowest level.

** l^ocate your pump as near the source of suction supply, l>oth vertica
and liorir.otit?illy, jis is pc^ssiblo nr convenient; but never place it in imclij
location that the sum of the following thre<? jtt?nis will exceed a total of 30 {
1. Height in (vvi from the discharge valves of the pump to the lo^r*t l»f
of the surface of the s\icrit«n water, 2, Totitl frictiun lo«i in •uetifia pi|
in fet^t head, 3. Total friction loss in feet head due to elbowii and
(assumed aa beini^ equivalent to the friction loss of 100 ft, of aame iiii {
pipe, for each elbow or tec).

^n

SEWAGE PUMPING STATIONS

661

"Lay your suction pipe so that it slopes away from the pump gradually.

A suction pipe should have no air pockets in its entire length, but should

be flo UJd that if air be admitted to it, near the intake end, with the pump

fitunding st'dJ, the air would rise to the pump or suction air chamV>er, and not

oketed in some high part of the suction pipe. A slope of 1 per cent, will

I md very satisfactory.

' Bt3 sure that your Buction pipinf^ is abstdutely tight, for a very small

air leak will cause a pump to work improperly, The auction pipe should

be te8t<?d with about 20 lb. water pressure after it has been laid and Ivefore

it is covered. If the test shows up a leak, fix it; it ts not good enough,

**Kccp the end of your suction pipe well under water. It should never
have leea than 3 ft, above it and 6 or S ft, will be much better.

•' If two or more pumps draw from the same suction pipe, or if water comes
to the pump under a head, a gate valve should be placed on the suction pipe
of eAcU pump, to enable you to open up any one pump cylinder for repairs
or examination without interfc^ring with the operation of the other pumps.
We recommend on larger sizes where practicable and not too costly, that each
pump have a separate individual suction line entirely independent of the
suction line of any other pump,

*'A suction air chamber will be found desirable in all cases, and indid-
peosabte in cases where the sum of the three items referred to in a previous
pHTAgraph ( the third) exceeds 10 ft. or when the suction pipe is long.

**A foot valve* is desirable in all cases (except when suctifm water comes
to the pump under a head) and indispensable when the suction lift exceeds
10 ft. By its use the pump and auction pipe are kept primed when the
pump is shut down, and it permits of easily priming the pump and suction
pipe if purposely amptied, thus enabling the pump to be easily started at
liay time.

" In all cases where the water contains sticks, weeds, rags, or other rubbish
a stjainer should be used on the suction pipe, to prevent them from getting
into the pump and clogging valves and passages. If a foot valve is used, a
^ ilaced outside the foot valve is beM; but if no foot valve is used, a

ner placed near the pump and so designed that by removing the
str^ii«.r ct)ver all accumulations can be removed, will be found most desirable.
Keep the strainer clear from accumulation of rubbiah.

*• When a foot valve is used, a drain valve should be placed near the surface
of the water, to enable the suction pipe to be drained when desired.

"A relief valve, set to blow at about 20 lb, pressure, should also be placed
on the suction pipe near the pump, to prevent the delivery pressure, if over
50 lb,, from accumulating in the suction chamber of the pump or the suc-
tion pi|>e. This does not cost much and may sometimes save you the coat
of replacing a broken pump cylinder or foot valve, due to carelessness.

"A check valve on the discharge pipe will be found ver>^ convenient. A
fat«« valve nhould be placed on ll^e discharge pipe outside the check valve,

I A foot^V»lve uo tt Kuctiim pipe for acwukc »« obifrtum»hl« b«c»uiit* of iLc ier«'Bi daD«i>r
of il« (3lt»u|inc witb iia*te. olath AOtl other •ub«tiif)nc>A. Jt in iho nuthnm' u|}imoti timt
«tttr|i rAJvo* nhoulcl bf» tiaiilUiNi »ti«iitf)ver poaatbjo, UiUs <?liijiirjiittiii£ tho cnro ti^tHMuiiU'y to
t0¥p them ill ofilof mticl r«ilucitia the friction wKite nmmiiK w tweU M the duticer uf
Uoubl», TUbw eommeoM «lao apply to Btfinwrm on U>« auftiati pit»«.

662

AMERICAN SEWERAGE PRACTICE

"A priming pipe should always be connected from the discharge pipe,
outside the gate, to the suction pipe, if n foot valve is used. This will enublfr
the pump ryUnders and suction pipe U:* be primed, if cmpt>% before 8tiu*ting.
If you have no suitable relief valve on the suction pipe, be very cureful, in
priming with this pipe, that you do not let delivery pressure aecumulut^ in
the suction pipe. This will be prev^ented by having the starting
valve open V>efnre you start to oi>en the priming pipe valve* This >'
always be open before starting your pump (whether yotj have a fo<it vaK*o
or not) as by this means the pump Is enabled to discharge the air froni the
pump cylinders and suction pipe through this starting valve a^inst a light
pressure. As soon as water is discharged through the starting valve, shut
it and open your steam throttle valve, and the pump will then discharge
through the diHeharge main, opening the check, valve automatically. If
you have a foot valve or a gate on your suction pipe, and no rehef valve,
be careful to open the starting valve at the instant you shut the pump down
and leave it open until after you have starte*! again, as by so doing ymt
prevent the possibility of pr<?saure accumulating in the suction. Th* fwt
cock in the force chamber of small sijce pumps is intended to be used in the
eame manner as the starting valve above referred tx5.

"I>o not pack the stuffing boxes too tiglitly, and do not let the packinic
Btay in until it get« hard and cuts the piston rods or plungers. Ilenew it
sufficiently often to keep it soft and pliable. If the pump runs baiUy, n\ake
sure that the pump valves, packed pistons or plungcr-s, and suctiou and
discharge conncctioQB are all right before examining the steam end/^

CENTRIFUGAL PUMPS

There is some confusion in the use of names for different typea
centrifugal pumps, and to settle the matter^ the authors have obt
the following definitions from George de Lavid, general manager
Henry R. Worthington, whose book on "Cejitrifugal Pumping Miirhin*
ery" contains the only explanation in Englii^b of the methods act
used in designing this class of machinery for the higheM pracl
efficiency;

** Centrifugal pumps comprise all thosie pumps where the water tl

high rotar>' motion by an impeller, which velocity is then con\ *>|

head, forcing the water up to a certain height/*

"Volute pumps arc centrifugal pumps where the water 1^ fft^ t*t ^mvp
the impeller in any direction and is taken up by n grudunlly eii I 1

surroimding the impeller, by which gradual enlargement t1
id changed into head. Hero the conversion takc« pUoe i i

manner, hence the low efficiency/*

"Turbine pumi>s arc centrifugal pumpa m which th"
the impeller 1 ' ' ' • ' ^

i«nlarged anil
th«-

tbey do not depend upon centrifugal force. They coaaist of & shaft provided
with % vane forming a complete screw thread. Tlie water travels in an
axial direction, being propelled by the spiral vane/*

**Propellor pumps are screw pumps in which only parts of the screw are
utilised* These parts are arranged around a hub and form a screw of multi-
plfi pitch, the rotor being similar to a ship's propeller/'

" Centrifugal -screw pumps have helical vanes developed on a conical
jBurf&oe. The piteh of the helix is constant for all radial distances from the
A%is. The water receives an axial or helical movement until it strikes the
cone of the impeller^ when it comes under the influence of centrifugal force.'*

Until c.omparati\'€ly recently little attention was paid to reBnementa
in the design of centrifugal pomps in America, although they were used
eJctensively^ The greatest interest in their improvement was shown on
the Pacific Coast down to about 1900, w^hen the good results obtained
«ith such apparatus in Europe led to a quite general interest in the
betterment of it8 design. Previously American centrifugal pomps had
been strong and durable, rather than efficient, but the attention paid
to them since 1900 has resulted in an improvement in efficiency. Iln-
lortiiuately this was not all that was needed, however, for the proper
design of the power end of the equipment is as important as that of the
pump, particularly w^hen electric motors furnish the powder. It waa a
rather surprising condition in the electrical industry' for some years that
the peculiar requirements of centrifugal pumps were overlooked in select-
ing motors for them, although the lack of efficiency in such combined
units called attention repeatedly to the necessity of adapting the two ends
of the plant to each other in a better way. Today, as Mr. de Laval has
gtated in his Imok already mentioned, 'Hhe designer of the pump must
carefidly consider the nature of his motor when laj^ng out the character-
istics of his impeller, and the electrical engineer should design his motor
to suit the characteristics of the pump," where the plant must work
against a variable head, in order to obtain the highest efficiency* This
is generally rec!ognizcd now and plants of this type are unquestionably
more efficient than they were in HlOO, although business competition,
poor spei'ifications and lack of tests to ascertain if guarantees have been
met have the usual retarding influence on progress.

Special Features of Centrifugal Pumps* — Tlie theor>^ of the centrifugal

pump as presented in most text-ljooks in English is quite simple. It is

tisrttjrned that the particles of water moving outw^ard between the vanes

t>f a revolving impeller are given a uniformly increasing linear velocity,

»o that all particloi at the same distance from the center of the impeller

i.u* ,. *},.., ..^^^ velocity. Then the reverse of the usual theor>^ for a

Jve an analysis of the pump, or the flow between the vanes

l^r nmy be considered as the f^ow through pipes under pres-

^* ♦o ^'hange in the internal hydrostatic pressure due to

664

AMERICAN SEWERAGE PRACTICE

centrifugal force. Both methods result in the same equations, and both
are smously at fault, for practical purposes, because all particles of water
at the same distance from the center do not have the same velocity.
The subject is treated in considerable detail in Prof. L. M. Hoskins'
''Text-Book on Hydraulics/' but aft^ reading his explanation of the
general principles of centrifugal pump action, the practical api^cation
of them in de Laval's '' Centrifugal Pumping Machinery'' will show what
a great difference exists between theory and practke and some of the
reasons for it.

The performance of a centrifugal pump is shown by characteristic
curves. Fig. 302, which reveal two important properties ol such i4>paratus.
The first is the impossibility of producing a greater pressure at any speed
than that shown by the curve. Hence, if the discharge pipe should be

\m

5QD

600

^^ 0

?X 3QQ «X

Gculon^ per MmuTe.

Fig. 3<>2. — Characteristic curves of centrifugal pumps for fixed overload
conditions vde Laval;.

suddenly clocked, there i5 no danger of rupturing it, as would be the case
with a reciprocatinc: pump. The second peculiar property of the pump
i> that at a given speetl and for heads between certain limits there are
two rate> of discharge. At lir^t sight this might be considered an indica-
tion of uncertainty of ojx^ration. which would be the case were the punip
di>charciiig into a larce lank in the imme».liate vicinity, so that there
wore pr:irtic:dly no friction head for the pump to operate against. In
this c;ise tlie luimp having the characteristics shown in Fig. 302 would
: ecin to «i:.-harce when the h»:^d of 1(X> ft. was reached, and would
Ci«ntin-.io i^^hiirging until about 1 1/> ft. head was reached, when the dis-
ch:irce w,i.;ld .:e:u<c and the pump could not l»e made to deliver water

^r SEWACfE PUMPING STATIONS 065 ^H

AC^n until the head dropped to 100 ft. Practically, this trouble is 1
firevented by means of a gate on the discharge pipe. By partly clos- I
ing lhi» iratr the head can be raised from 100 to 115 ft.; the pipe friction I
pla^s some part, also, in the regulation of the flow. If the friction head J
wrre increased by further i hrottling the discharge would be cut down, for ^^M
capacity and friction Iiead arc related in an inverse ratio: if the friction ^^B
head were reduced after it reached 115 ft, the discharge would be ■
increased. 1
Arjoiher special property of the centrifugal pump mu^t be kept in ^^B
mind. If the head were suddenly redurcd by a break in the discharge ^^M
pi[^ or some equivalent cause, the pump would discharge more and ^^B
ition* water until it reached its capacity for such a head. This would 1
throw a greater load on the motor, however, and might injure it if the ■

Speed, c p.m. ^^|
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)3.— Performance of a 2-mch centrifugal pump imdcr tea

the pump were not designed so that not more than a c
of overload could be imposed in any case. Mr. deLavi
lid not exceed 25 per cent.; it is sometimes consid
. ^ The ordinarj* goo<l design gives a capacity of 70
iliat at maximum efficiency, with a 25 per cent, varia
bout 5 per cent, variation of efficiency. A pump caj

nphU M&fVAieA pumptiic rtAUon there ftre two Horuoatat cwntrifugAl
her II 2*Km,, un \Xx*^ rtiKine-roora floor bpcJ tio ft-in, «iibmi»r«od ecu
by thfce-phMiio intlurtirin motorv, the flrnt by » 175 l»,|»., the B^co
the thinl by u 50 h p. The first two have n TfttAcl rapacity 30 per
rotjuircrl to dnv*' th*? pumt>« under normul comliiioiiA. "Tb«* bt(*iH.

^ "f .. f. f .1, 1 i by ft c^ntri*«jfal pump ns ita »uttlcin lift ia

Lii the powrr rtMuired to drive tlw? pump, I©d to t
. ahtit thti t:»puoUy ol tbQ itUtiun enn bi! ereatly i
■n in the •torra-wnUtr pump well/* (fiiitf. Rfcord, April 21, 1000.)

certain ^H
il says ■
erably ^M
to 125 ^H
tion of V
[1 be so ^^1
ft ^^^1

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666

AMERICAN SEWERAGE PRACTICE

designed that the power curve will be nearly conjstant, according to de
Laval, while the efficiency is maintained.

The characteristic curves of Fig, 302 were taken from a pumpatcoor
stant speed; the usual basis for designing centrifugal pumping plants. A
good centrif ugiU pump can be operated at a considerable range of speed*,*
however, witliout any great loss in efficiency. This is shown in Fig. 303,
which gives the cur\'es obtained in a test of a 2-in, horizontal single*"
stage stock pump with an ojjen impeller, tested at the New Mcxic
Agricultural Exf)erinient Station by B. P. Fleming and J. B. Stofl
king. The eificiency in this test was figured on a total head compris

the lift from the suction elevation to the discharge elevation pliw ll

friction head plus the velocity head gained between the suction an^
discharge pipes. If the velocity' head in the discharge pipe were Icsd
than in the suction pipe, the difference would have to be subtrncted
in ascertaining the total head.

This pump was supplied with an impeller in which the angle betwpeo
each vane and the tangent to the circumference of the impeller was 30
deg. In order to ascertain what effect this angle had on the perfornmii
of the pump, three impellers were made having angles of 0, 60 and 90 dc
respectively, but none did so well as the stock impeller.

The impeller of a centrifugal pump is either open, when there are {
plates on the sides, or enclosed, when each side has a plate and the wa
has no chance to touch the side walls of the pump ca^^ing during '
entire time it is within the impeller. The enclosed t>'pe reduces the
internal friction of operation somewhat, and is employed where econo
ical operation is desired; it has been used for pumping sewage, and 1
larger sizes may be as well adapted for such work as pumps with op
impellers. The latter are usually recommended for small -
pumping plants with low to moderate lifts and Tables 167 an
give the data necesrsary to select the size best adapted for small
tions* The former table was supplied by Henry K. Worthington
March, 1914, and relates to that firm's Class C pumps. The seen
table was supplied in April, 1914, by the Alberger Pump & Condenser (
The tables of centrifugal pump capacities, speeds and power requil
ments printed prior to 1914 should not be used by the engineer wit ho
being checked, as material changes in them are needed. The reader]
particularly cautioned against applying tabular data relating to spcci;
designed pumps with enclo««ed imijellers to stock pumps with opt^n imp
lers, and also against confusing single and double suction pump**,
turbine and volute pumps. Finally it should be kept in ndnd tfa
liberal water passages are needed in pumpinp sewage, and if flu
to be handled is small, it may not be advisable to use the mi

^ But ttlertrfc motors of •ome typos «re JneupAhlii ol muHi npf&ivd vaftuilioti, «o *
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ittWtfi«i

SEWAGE PUMPING STATIC

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^^ ^^ sijc; (^^

11

: -^ OB ae 1*30 « t*

OC W NO -^»-

I*** Q^ rt«a^

:^ «di. s^ <po 0009 r*>o 000 o^ «e9 000 wt^

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it

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"r iriorig y irsi Iriril

>.^^ t^o s« c«t? o*n OM M«<< o^ai 1*9 ^e go«>«

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«£4 e>it<i tan «^ •«•':

9« 90 ao OS «««<•

668

AMERICA!^ SEWERAGE PRACTICE

o

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o ^

li

s §

3 ».

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5 *

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-^ O ^ t-

♦ceo
liJ i5' .^ § "^ "3 ^ •« o »e «o

^ *4 V^' .4 4M

i Si

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9 r^ csi ^

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15 i o s - -

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Is i5 ^ R ^ t2^'3„c>(»»2«*CM*ra-i*So5o2oraS»

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,goi

2 S 12

I ^ U5 Sr U3 -S ^

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; a

HI

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s

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tt to n e 09 u3 <

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I CO &< 3!} Oh '% Cl* (« & Z; &4 ^ £U X Cm rs 3k ^' £U ^j; SU to pU gr, •-

§ i i § I I § i

^ c4 ^ «d !«' ^* rf 3f

iJ

2 2 S 1

^ I""/!

SEWAGE FUMFINO STATIONS

669

I owing to their greater UabiHty to interruption when running on a
|uid containing many kinds of solids.

The screw pump is used where large volumes of water have to be
aoved against very low heads. In sewerage work, they have been
aployed mainly in producing a proper flow through large conduits
supplying water for flushing rivers, as at Milwaukee, or tidal inlets, m at
Brooklyn, The peculiarity of the pump is that a certain amount of
Dck is inevitable, and consequently the screw type can never be as
Scient as a well-designed centrifugal pump. The latter, however, can-
not be built to operate i^atisfactonly for some of the conditions for which
tie RCTCW pump is well a<iaptrd.

Efficiency of Centrifugal Pumps.— The nominal efficiency of a cen-
rifugal pump tlependa upon the total head, which has never been do-
aed by any authoritative bo<iy, and at present ihere are three defin-
feions of the terra among engineers. The first is the algebraic sum of the
scharge head and suction head, the second adds the velocity head in
tie discharge pipe to the first quantity, and the third adds the difference
etween the velocity heads in the suction and discharge pipes to the first
uantiLy. The third meaning of the terra is the accurate one, theoretio-
jlly, for it represents the actual head pumped against. The pump must
> overcome various resistances due to the churning of the yjf titer and
ther sources of water friction, the skin friction between the water and
be impeller and chamber walls and other thing-s, of all of which very
|ttle definite knowledge has been acquired yet. In spite of this lack
information there has been such great improvement in design that
ireu small centrifugal pumps can now be had under a guarantee to
bow higher efficiencies than the 40 per cent, which was about the best
>tainal)le from an ordinar>^ volute pump in 1895.
According to George dc Laval, 55 to 65 per cent, efficiency should bo
t>tained with the mast efficient t>'pe of pumps delivering 75 to 25D gal.
er minute, 70 per cent, with those of 250 to 900 gal., 70 to 73 per cent.
L those of 90€ to 3O0O gal., 73 to 75 per cent, with those of 3000 to
I gal, and 75 to 78 pur oent. with those of 6000 to 10,000 gal. With
aps of capacities over 10,000 gal., 75 to 85 per cent, efficiency ts
fc>tainable, he states. Side entrance or sin gle suction pumi>s give slightly
efficiency* The late William O. Webber expressed this effect of
zc on efficiency in Engineering News, Jan. 10, 1907, lis follows: A 2-m.
Qp giving an efficiency of 38 per cent., a 3-in, pump giving 45 per
at., a 4-in. pump giving 52 per cent., a 5-in. pump giving 60 per cent.,
i 6-in. pump giving 64 per cent., are proportionally as good as an 18-in.
[imp with 77 per cent, efficiency and a 32-in. pmnp with 80 per cent.
The efficiency of j^mall centrifugal pumping plants as actually operated
Southern California was tested in 190<i by J. N. LeConte and C. E.
tait for the U. S. Office of Escperiment Stations, which published the

670

AMERICAN SEWERAGE PRACTICE

Table 169. — Tests of Steam-dbiven Centbifdoal Pumping Plantb
(Le Contb and Tait)

Dis-

Suc-

Dis- ' RniJ

j5 Engine

charge

see-

ft.

Indie,
h.p.

Water
h.p.

Uon,
ft.

charge,
ft.

svtr
sisd

1

10' X 6' simple

Vert. comp. 6' sue.

0.578

31.8

10.7

32.0

132.0 1 7 1

non-oon. 75 h. p.

7' dis., 1003 r.p.m.

nom.

2

9' X 12', simple,
non-con. 35 h.p.

Vert, comp., 8' dis.,
700 r.p.m.

1.37

31.7

14.7

0.0

94.3

7

nom.

3

lOr X 30', simple
condens. Corliss
118 r.p.m.

Vert, comp., 9' sue,
lOr diB., 803
r.p.m.

0.89

107.8

41.3

17.8 195.6

11

4

8', 12' X 22' X

Hor. single two 20' 54.77

139.0

83.7

13.54 -0.06

9

16' trip, conden..

sue. 30' dis.. 140

140 r.p.m.

r.p.m.

5

8r. 121' X 22' X
16', trip, conden.,
150 r.p.m.

Hor. single two 20'
sue. 30' dis.. 150
r.p.m.

52.02

134.0

78.9

13.54

-0.06

7

6

16i" X 28' X
20"comp. conden.,
151 r.p.m.

Hor. single, 44"
sue. 44' dis., 151
r.p.m.

95.4

239.0

106.4

15.0

-5.0

15

7

16' X 26' X 18',
com p. cond., 164
r.p.m.

Hor. single, 44'
sue, 44' dis., 151
r.p.m.

87.4

216.0

96.4

15.0

-5.0

13

Table 170. — Tests of Centrifugal Pumping Plants Drtv'en by Internal
Combustion Engines (Le Conte and Tait)

1 Engine

Pump, centri-
fugal

Suc-
tion,

ft.

Head.

ft.

Dis-
charge

BOC-

ft.

Ind.
h.p.

Water
h.p.

Runs

aver- Fuel
aged

'

'

1 i 0' X 12', 240

4' single vert.

0

44.4

0.328

5.64

1.65

16 Dis-

r.p.m., 11 h.p.

tillate

nom.

2' Sy^fl" X 14*, 12 h.p.

4' single vert.

20.5

41.4

0.671

16.3

4.70

9

Dis-

1 nominal.

tillate

3 1 16' X 18", 180

10' single vert.

0

11.31

5.94

38.0

7.60

8

Dis-

1 r.p.m. 50 h.p.

tillate

, nom.

4 lir X 18', 200

5' comp. vert.

8.3

88.3

0.820

26.5

9.05

12 ' Dis- 1

r.p.m. 32 h.p. nom.

tillate

5 9J' X 20'. 2(U)

8* single vert.

18.6

49.3

1.36

35.2

10.4

13

Di»-

r.p.m. 30 h.p.

tilUte

nom.

6

10' X 18', 30 h.p.
nominal.

6' single vert.

21.0

41.0

1.51

29.3

10.6

7

Dis-
tillate

7

10' X 18', 18-)
r.p.m, lU) h.p. nom.

7' comp. vert.

20 . o

73 . 0

1.00

26.7

11.4

16

Di»-
tilUte

H

11' X 20", 180
r.p.m., 35 h.p.

7* comp. vert.

23.0

07.4

1 . 33

40.8

13.6

8 I>is-
. tillate

nom.

9

lOr X 22', ISO
r.p.m. fiO h.p. nom.

12' sing, horiz.

0.5

48.-,

4.06

63.1

30.9

13

Dis-
tillate

^ Same pump and setting used also in Test 1, Table 171, electrically driven pUnts.

SEWAGE PUMPING STATIONS

G71

suits in its Bulletin 181. Tables 169, 170 lind 171 summarize the
Idiiig reeults And indicate the service the plants were giving without
rli miliary tuning!: up for tei?t!4.

jThe intertiul t'ombustion engines were using, as a rule, engine dis-

fttes of 35* to 48° Beauni^. The physical condition of the planta

ried widely, A fair average of the conditions indicated a probable

dual overhead charge of 12 to 15 per cent, for depreciation, 6 per

at. for interest anrl 1 per cent, for taxe^s and insurance. The amount of

tillate used per indicated horse-power-hour varied rather regularly

pm 0.154 gaL for the smallest plant to 0.1 gal. for the largest. The

liouat used per water horse*power-hour varied more widely, for it

ended not only on the engine but also on the general efficiency of

I entire plant; a fair average was from 0.5 gal. for the smallest plant

\ 0;2 gal. for the largest.

|The electrically operated plants showed a higher plant efficiency than

Dec driven by intefnal combustion motors. Le Conte and Tail con-

ided from the tests in Table 171, and others where different type* of

aps were used, that electrically op cm ted plants of a rapacity of 5

Ster-horsc-power should have 40 per cent, efficiency, and the efficiency

tthoiild rise with the capacity to 55 per cent, for a plant of 40 water-
^krse-power.

rABLB 171

Tests or Centkifugal Pumping Plants Driven by Electbic
MiTTORft (Le Conte and Tait)

^^f^S h.p, itiduc, ttt>-
eye. 31-ph. 440-v.

AO h.p. todae. 720U

•It.. 3*pli.. 2rM»0-v
40 b.p. iudlu«>,, 60>

eyo,, 5-ph , Uii-v.
ZO ii.p. itirliic, 00-

eye. i-ph, 560-v.
100 h.p, iodue.,

1200 All., 3.ph^

400-v

MoU)r

Puiup, cdtithfuital

Vert, Aiuglo, 4' «uc.,

fl* ai«. 91K) r.p.m.
Vert- sjDclc. 8' rue.

10' UiB, 440 rp.in.

Vert. «iogfo y and

G" iittc., 71' dia.

ft5.1 rp.m.
Vert. *iomp.t no* *uc.,

14* dit . 1100 rp.rri.
Vert. comp. 8' dift^i

712 r.p.m.
Vert, cottip. 7' »uci,«

8' db , 723 rp.m.
Comp.. fl* Biic., 10'

dii,, 700 r p.m.

Suo-

tiun.

ft.

Head,
ft.

chttrge,

KUo-

w»tta

20.5

19 6

25.1

41.4

3,0

eio.a

28.4

94.9

97.3
180.0

0.714

2.21

1.2<1

2.97

l/SH

I 10

1.82

10.8

9.4

10.4

41.2

23.8

23. A

53 1

Water
hp.

5.01
5.02
8,57

9.45
14.7

15.3

Eun«
iiver-
ftged

It

13

The Bteiun-driven phints all burned crude oil as a fuel, and their

'nciemty did not differ definitely from the efficiency for gasoline or

«tric plants. The smallest plants required about 2.5 gaL of crude

I per water horse-power-hour and the Uirgeat plants required about

mm

672

AMERICAN SEWEHAGE PRACTICE

The investigation convinced Le Conte and Tait that there was % 1
of Rood design and maintenance about most of the internal-corn bustW
plants visited which, could it be corrected so as to bring about at e^c
plant the same efficiency found in the best plant, would have redufl
the consumption of gasoline in 1905 from 90,000 to 63,000 »;al,
most of the plants the annual fixed charges for interest, doprcoiad
and taxes far exceed erl the expr^nse for gasoliue, attenthinee and n?pain

Setting Centrifugal Pumps. — There is consi<ierable diflfcren^x?
opinion regarding the best arrangement of the punip as resp^jcts i
supply. Some engiueers favor submerging it; but pump makers
pose this^ mainly because an expot?ed pump receives better care llil
one which is submerged in sewage. Others place it as near as po
to the water level in the suction well, William O. Webber stat^i
Enginemng News, Jan, 10, 1907, that suction lifts of 10 to 15 ft.,
enlarged suction pipes and taper connections, would give better i
ciencics than were obtainable with a submerged pump,

A type of centrifugal pump setting has been developed for low-he
irrigation work which has certain advantages where it is applicttblj
The pump ia at the highest point of the suction and discharge pip
and with them forms a siphon. Thk arrangement has been adoptrd I
(ieorge G. I'^arl for the eleven new pumps for the New Orleans drain
system. These are of the screw type (Eng, Nett% Jan. 15^ 1914) ei
of 322,000,(KJO gal daily capacity against a head of 5 to 10 ft.

There must be no vertical bends in the suction pipo where air (
collect, and, as in all piping of this class, special pains must be
to make the joints air-tight. At the sea level it does not pay to try I
use a higher suction lift than 25 ft.; the greatest suction lifts at cl«
tions of 2(H0 and 5280 ft. are 20 and 16 ft.» respectively. The i
pipe is usually one size Uvrgcr than the discharge pipe.

The discharge piping should be as straight m possible, and it Li!
times considered advisable to bolt an increaser to the outlet of the pu
so as to make the discharge pipe as large as the suction pipe.

In starting a centrifugal piunp after priming it, the valve of the*
charge pipe should be closed until the impeller is running at ita aoffl
speed, when the valve should be opened slowly. In case the head|
be reduced below that for which the pump wa^ deeigned, the di
pipe valve should be partly closed at once so as to tlirottle the dbch
by creating an additional friction bead and thus prei'eut overlo
the motor.

Priming is the procesH of f='Xi)eIling air from a centrifugal pump I
is started, for if the impeller runs in air it caimot create enough i
to raise water to its le%'cl. If the pump is alwaj*9 submerged or weni
its supply under a head, priming is not needed. T' ly

hot water or any other liquid giving off a vapor, t he 4

c pump under tjomc pressure, in order to prevent the collet'tion
of vajH»r in l\w chamber, which will stop the discharge.

If the suction pipe has a foot^valve to prevent backward flow, the
ainiplent method of priming is to fill the pump and the suction pipe with
water from a street pipe or other permanently reliable source, wluch
can be admitted through a valve tappcrl into the top of the casing. In
somo CB^€^ it may be necessary to lift the water from the well into the
easing of the pump by a steam injector. Where a foot valve is not used
and the pump is not supplied with water under a head, a check valve
may be placed in the suction pipe close to the pump and an injector may
be tupped into the suction pipe just below the valve, with it. "5 flischarge
pipe tapped into the top of the pump casing. Another method of prim-
ing is by exhausting the air in the pump casing and suction pipe, which
iults in water being forced into them by atmospheric pressure. If
steam or water ejector or an exhaust pump is tappcrl into the top
of the pump easing, the discharge pipe must always be closed while the
ejector is drawing water up the suction pipe and into the casing*

Where the heads against which the pump works exceed about 30
ft., a check valve is usually placed in the discharge pipe near the pump,
in order to protect the latter. The casing of the pump near the center
of the aides is not strong and it is very difficult to brace it with ribs.
If the pump were to stop running suddenly the sudden checking of the
velocity of the water in the pump would cause a heavy pressure on these
relativeb^ weak portions of the pump, particularly if a foot valve were
U»ed. If a check valve is employed as suggested, a pipe can be tapped
into the discharge pipe just above it, and water for priming can be ob-'
lalned in this way. Centrifugal pumps as large as 12 in. can also be
primed by means of ** priming elbows'* between the suction opening of
the casing and the suction pipe. These elbows arc provided with sujall
hand*pumi>s which draw water through the main suction pipe and de-
Urcr it to the pump, where it is retained by a clack valve in the elbow.
Various other modifications of these methods have been used.
An elaborate system of priming was insi ailed at the pumping station

r|t Salem, Mass. Here there are four horizontal centrifugal pumps of
M^'.OOO gal, capa(iit>' each, electrically driven. The priming is done
by two Kriowles 4 X 4-iu. dry-air vacuum pumps driven by a General
<if 5J h.p. The installation Is illustrated in Engineering
, 1908, and is so arranged that any one or any comlnnation
pi the maiij pumps may be primed by the use of either or both of the
priming pvunps, Ono-inch pipes are run from the highest part of the
pump chambers to the back of the switchboard of the station, where
^' \ aires contrnlling e^ch hne, and the pipes are then joine<l and

^ to the bottom of an air-tight chamber. Huctiuu pipes from
the priming pumps are connected to the top of the same riiamber in

674

AMERICAN BEWERAOB PRACTICE

which is i>kocd a balanced port valve connected with a copper*^
whioh controls tlie valvo. This arrangement was designed t«> pp
the drawing of sowago into the vacuum pump. To each of the primii]
pipoB between the valves and the main pump there is connected a coru-"
bined pressure and vacuum gage, with a dial mounted on the wall
near the board and on the side of the air-tight chamber there ia placed
a water gage. It is stated that this arrangement has proved satisfac-
tory except for trouble from leaves and similar objects which enter
the chamber; this^ has been remedied by placing a screen box in the pipe
from the main pumps.

The foot valve* at the bottom of the euction pipe should have an area
about 50 per cent, larger than that of the suction pipe* At the bottom it
is often provided with a strainer with openings large enough to permit the
passage of all objects which will not obstruct the passages in the impeller.
This strainer should not be the main reliance to prevent sticks and othex
objects from entering the pmnp, but should be regarded as an additioiuil
precaution. If the foot-strainer is relied upon to do all the screening, it ia
likely to become clogged speedily where sewage is pumped; in fact, a
foot valve and a strainer on a sewage pump are ver>" objectionable and
should only be used when absolutely neeesfiarj'. The clacks in the
valve should have their hinges on the outride of the valve-seat plate,
BO that when they are raised they will offer as little obstniction &s
possible to the jjassage of the sewage.

Centrifugal pumps must bo held finnly in position and aU shafting
must be well supported to secure satisfactory operation. ** A conibtned
bedplate for the pump and motor should be leveled up by wedges^ tbt
pump and motor placed upon the facing strips and lined up so Uiat the
faces of the pump coupling are parallel, and the pxmip and motor run
freely with and without coupling bolts in poaitioa. The b^tdplate
should then be grouted into place so that it is absolutely rigid. After the
foundation liolts have been permanently set the suction and discharge
piping may be connected" (De Laval).

*'The best bearing for the vert-ieal sKaft is an important element in ibc
design. At 8arat<^Ka« where a bearing several inch^^s iti diarn«'ti»r, wrth
alternate l*>ase rings of brass and steely submerged in oil, wm..- 1,

considerable trouble was encountered because i»f heating. At i

regular Reeve's propeller bearing with an oil -collecting pan ami i
lifted and circulated by centrifugal force, aa is done in niotiir work^ w^u
with entire succees/* (Frank A. Barbour.)

The Saratoga pumps were three in number with G*i i
ami were driven by 20-h.p. induction motors. The 1'-
5-in. driven by 15-h.p» induction motors, Tlie former had a comhiool
efficiency of about 55 per oent. and tlie latter of 12 per cent

Tiie s^hafis oi vertical pumps should be steaiiicd by bearinge ft to 101^

< %tm tciotiiou Oil paum ML

SEWAGE PUMPING STATIONS 075

apart, vertically, for such jjumps are somewhat more difficult to operate
than those with horizoutal shafts. The smaller the shaft, the closer should
be the Hteadj" bearings. A slip coupling io the verticaJ shaft between
the motor and pump may be desirable. If the vertiiial shaft is short,
the thrust bearing supporting the shaft and impeller may be in the top
of the pump frame, but if the shaft between the pump and motor is
a long one, or the pump is submerged, an independent thrust bearing
at the top of the shaft just under the motor is desirable. The bearinp
for the pump and motor are standardized by each manufacturer, but
the purchaser should satisfy himself that they are ample for the hard
service of sewage pumping.

Prime Movers. — If a centrifugal pump is driven by a motor, the latter
should not be too small or it w^ill operate under an overload much of the
time; if it is too large, the cost of power will he neetUessly high. The
size must be based on a consideration of both the normal and maximum
conditions. If the head varies, it is desirable to change the speed of
the pump, and the motor must therefore permit speed regulation, or
some such form of control as that used at Dallas and Lebanon by
James H. Fucrtes, de-scribed later in this chapter, must be adopted.
The proper design of a combined electric unit calls for special knowledge
id for ordinikry sewage pumping installations the best equipment will
irobably be obtained when the working conditions are stated fully and
manufacturers are left to furnish the machinery under guarantees as to
its efficiency and capacity. In handling sewage, slow speed and low
efficiency are not such drawbacks as que^^tionable reliability.

''When direct current is available, it is advisable to use motors of the
vnriable speed type, esj>ecially in cases where the head or capacity is subject
to change. As standard induction motors run only at constant speed, it is
necessary to vary the capacity of the pumps by throttling the discharge;
when the capacity or head changes considerably, it is most economical to
accomplisli the work with two units, operating then in series or parallel as
the fttTvice demands. The shunt- wound direct-«!urrcnt motor is usually
employed for driving centrifugal pumpa, but in cases where the voltage or
load fluctuates considerably, better results can be obtained with the com-
pound wound motor. This type is also recommended when the motor is
automatically started. For a lu^m a ting-current motors, the squirrel-cage
lypi* is most frequently selected. This type of motor, however, requires
a high fitacting current, and should not be used when the power av^ailable is
Itmiied, as it causes a disturbance in the line. The sUp-ring motor takes a
very small excess current at starting, and b therefore recommended in such
(Henry R, Worthington.)

The utiUty of electrically-driven centrifugal pumps for small sewerage
systems m shown by some figures in the 1911 and 1913 reports of Chief
Engineer Dexter Brnckett of the Metropolitan (Boston) water-workij,

676

AM ERICA S^ SEWERAGE PR ACT WE

The ptiiopiag of the sewage of Clinton, Mass., in the former year
done by a steam-driven plunger pump and in the latter year by a 12-in,
single-stage centrifugal pump dri%Tn by a 40-h,p. squirrel-<?age motor.
In 1911 an average of S29»000 gal. of sewage was pumped daily and in
1913 1,008,000 gal The labor charge in 1911 was $1,715.34, fuel cost
$1,104,88, and repau^ and supplies S194.63, a total of $3,014.85. This
gave 20.1 cents per 1,000,000 gaL as the total cost of pumping 1 ft. higlu
In 1913 the charge for labor was $1,342.51; current, at $5.30 per 1,000
kw.-hr., $603.82; coal for burning sludge and heating, $227,04; repairs
and supplies, $321.30; total, $2,495.27, or 13.8 cents per 1,000,000 gal.
1 ft. high. This figure of 13.8 cent^ averages 18 per cent, less than the
cost during the previous 13 years of operation.

Sewage pumps are usually of the volute type, as the heads are so V
that the diffuser of the turbine t>T>e is not worth its cost. The sin
suction pumps have a casing of relatively large diameter, and arc the
fore preferable for low and moderate speed prime movers and for belt
drives. Manufacturers do not usually advise their selection whore the
heads are more than 80 ft. The double suction voluta pumps have much
smaller casings than ibc single suction pumps of the same capacity and
consequently oan be run at high speed for which they are best adapted*
When so operated they will work well against heads of 150 ft. and even
more in well-designed and operated plants. They are frequently used
with direct-connected steam turbines. Vertical double-suction volute
pumps are used in the sewage pumping station at Havana^ Cuba.

There are two distinct types of centrifui^&l installafeiona i! ' ^

steam engines. The first uses a high-speed engine, with a i

speed of about 800 r.p.m. and an average speed of about 6<Jil r.p.m.;
These are not high speeds for centrifugal pumps, however, and eonsc*
quently steam-driven units frequently have larger inpeUers than ihoet
run at the higher speeds which are regularly employed wnth direct-
connected motors. For small capacities, a simple engine is used, while
for larger capacities a compound engine is needed at times, in w^hioh cjis«
the pump is mounted between the high-pressure and low-pressure cndf
of the unit, on the same baseplate. Complete engine-driven units
are supplied by the pump manufacturers in many siaes and cmpnr
but on account of the speed limitations they are not available for all .
po«es for which centrifugal pumps can be used- Where large amounts
sewage have to be handled, and the pumps run continuously for lo]
periods, the engines are compound condensing, and sometimtii tri]
expansion. The lirst American triple-expansion engines foff scwi
pumping were probably those in the pumping stations of the Bost^
Metropolitan sewerage district. The centrifugal pumps hiMl vcriii
shafts with a crank at the top: the engine iryUndei-s were honionl
arranged radially about the pump shaft, to the crank ol whioli

me

11

SEWAGE PUMPING STATIONS

677

ooanected iudependently, their axeis making angles of 60 deg, with

each atlier. The Deer Isknd station is typical of these plants. It

Lima one 60-in. and three 42-in. vertical punjps. The contract capacity

Jt)f one pump was 100;000,000 gai. againj^t 10-ft. head and of each of th4

Dthem 45,000,000 gal. against the game head. The average duty

Iduring 1911 was 52,600,000 ft.-lb. per 100 lb. of coal; a little more

I than half the duty guaranteed by the builders in the case of the large

pump. The average quantitj^ of sewage handled dady was 52,8riO,000

gal. and thp average lift was 10.95 ft.; the ratio of this average pump-

lage to the plant capacity illustrates how vain it is to expect high effi-

[ cieney m sewage pumping. The force employed comprised 4 engineers,

1 relief engineer* 4 firemen, 3 oilers, 3 screenmen, 1 relief scrcemuan,

and n laborer. Georges Creek, PocaJiontas and New River coal was

used costing $3*92 to $4,109 per gross ton. The cost per million foot-^_

gallons was 12.241 cts., made up of these items: labor, 6.162 cts. ; coa]^|

11475 ctu.; oil 0.129 ct., waste, 0,046 ct,; water, 0.926 ct.; packing,

CL098 ct.; miscellaneous supplies and renewals, 0.405 ct. Labor

l&t the screens amounted to 1.357 cts, and is not included the 12*241

'cts. for pumping. During the same year the cost of pumping at

i>ther centrifugal stations was 10.982 cts. at East Boston, with

^800,000 gal. daily pumpage, 10.993 cts. at Gharlestown with

J2,600,000 gaL pumpage, 58.837 ots. at Ale wife Brook with 3,012,000

^fj. pumpage* At the Ward St. station having two 50,000,000 gal.

rertical triple expansion pumps and an average daily pumpage of

^2,600.000 gal, against 40.31 ft. head the cost was 7.887 cts.

A number of small steam turbines have recently come on the market,

^B'liieli can bo used for driving centrifugal pum|>s. Their use in this.

onitection has mainly been for auxiliaries in large stationary or marii]

plants, although a few have been used on water-works service.

ftlernal combu-stion engines are xmed for sewage pumping to somel

Ktent. In a few cases they operate on natural or illuminating gaal

producer gas at SiUt Lake City) but generally some form of liquid|

luel i* used. - As they have no overload capacit>* like steam engines, they

be selected with careful attention to their ability to meet th«

amum requirements.

SPECIAL PXTMPS

lous special forms of pumps have been occasionally uned for raising
The air lift huH been employed with sewage at Hampton,
England. The Liernur system^ in which the sewage is moved by pro-
duciog A vacuum in the discharge pipes, was taken up in England about
WlO, after being almost forgotten for many years, except in Amnt^rdam,
W^en and Dordrecht. The Humphrey internal eombustion pump

tJ78

AMERICAN SEWERAGE PRACTICE

{Bug, Ntws, Dec, 2, 1909, and April 17. 1913), although never used for
sewage, is a new apparatus which may prove useful when its perfor-
mance in water- works service has been of sufficient duration to shaw
what are its practical merits and drawbacks. An Adams sewage lift,
such as is used in a nimiber of EngUsh towns, was employed with satis-
factory results in Salem, N.J,, until it was abandoned in 1912 on account
of the reconstruction of the sewerage system. Such sporadic installatious
of unusual apparatus for raising sewage are too rare to merit description
here, and among special pumps the only type that now (1914) has an
established position in sew^eragc work is the ejector, of w*hioh the ElliSj
Shone, Priestniaii, Pacific and Ansonia apparatus maybe mentioned aa
examples.

The general arrangement of an ejector plant may be explained by a
brief description of an installation of Ellis apparatus made in Schenec-
tady in 1907, under the direction of City Engineer L. B. Sebring. The
purpose of the plant was to deliver house sewage of a low-lying ilistrict
acroes a high ridge which w^ould require very heavy trenching if a
gravity sewer were installed. The machinery was placed in a 26 X 1 1
ft. concrete chamber below the street surface, and comprised four ejectors
caoh of a capacity of 100 gal. per minute, oi>erated by compressml
air supplied through a storage tank by two electrically driven compres-
sorsj with a combined capacity of 340 cu. ft. of free air per minute. The
ejectors were connected to an 8-in. pipe header leading to a 10-tn* inlet
pipe.

As soon as an ejector was full of sewage a valve at its top wm
automatically tripped, admitting compressetl air from the storage tank
at a preswiii'e of about 30 lb, per square inch, which discharged the sew-
age through an S-in pipe leading to a gravity taewer about 1900 fL
away. The vertical lift was about 21 ft. As soon as the ctm*-- *-
of the ejector were discharged, the compressed air was automaT
cut off and the ejeclor was ready for service again. Th'
ated in rotation, the interv^al betw^een discharges being •;
the rate of flow of the sewage.

The motors and compressors w^ere placed at one end of the chui
about4'l /2 ft. above the floor on which the ejectors rested, Aftti i
discharge the supply of air in the storage tank was automatically re-
plenished. The tank was fitted with a pressure regulator, and when
the pressure fell below a predetermined point the hand on the gage made
an electric contact whioh caused compressed air to be adnii ' * :\
piston operating the stfirting rheostat of one of the motors,
operation of the compressor had brought the proasure in the * '
tank to the proper amount, the pointer on the regulator made a j
contact and the motor was automatically stopped, tlndisr ordit
conditions only one motor and compressor were rt»quirod to

SEWAGE PUMPING STATIONS 679

and the second compressing outfit was held in resen^e. II tho
first compressor failed to operate, the second motor was put in operation
itomatieally by the pressure regulator on the air tank, which had a
cond electric contact point on its dial set for a lower pressure than tlie
due first mentioned. An alarm system was also installed in a neigh-
l>oring fire department house, which rang if both motors failed to operate.
At Cambridge^ Ohio, the sewa>?e of a small suburban ilistrict is raised
about 35 ft., not including the friction head in 500 ft. of 6-iu cast-iron
force main, by a Pricstman ejector, supphed with compressed air by a
compressor which is driven by a Backus water motor. Water for the
motor ia supplied free by the city. The plant with the building, but
exeluding the force main, cost $263 L

Apparatuii of this general type is manufactured by a number of corn-
pan ien and israther widely used, although comparatively few installations
have been made on city sewers. The main field of such ejectors has
been in connection with the drainage systems of large buildings having
basements and cellars below the elevation of the street sewer, so that
the sewage and hquid wastes from these parts of the structures must
be pumped. The only t>^pe of ejectors which has been extensively
employed in municipal w^ork is the Shone. One of the first important
n*..at< of this sort in the United States w^as at Winona, Mrnn., and after
1^ h:M.l been in service for some year^ a second plant of the same tiype was
introduced. Another installation which attracted considerable attention
when it was put in w^as made at Fair haven, Mass. Of late years it has
been overloaded at times» The clerk of the Board of Bewer Commis-
moners, Norman M. PauU, informed the authors in 1913 that the ejeo-
tors have operated very well considering local conditions. Two of the
four stations where they are located are in particularly wet places and
Jilthough the chambers arc cither of cast-iron segments calked with lead,
or boiler plate, they are by no means watertight, and many times the
ejct'tors are partly or entirely submerged. Six of the ejectors had been
m use 17-1 /2 years and two of them for 9-1 /2 years when they were
overhauled, and their conriition w^ivs good. A feature of their operation
which has to be conj^idered in February and March is Uie formation of
ico in the valves and pipes through w^hich the air ei?capea.

At Far Rockaway, a leading seashore resort in the Borough of Queens,
N. Y., there are three Shone ejector stations and two automatic electric
stations. Each ejector station contains two ^ioO-gaL units furnished
b with air at about 20 ll>. pressure by tliree compressors in the main sewage
jumping station of the place. The electrically operated stations are
of much larger capacity^

The Shone ejector as before stated, is operated by compressed air.
I In general ap|>carance and method of oj>eration are indicated in Fig*
301 and the accompanying description furnished by the makers:

680

AMERICAN SEWERAGE FRACTWE

*'It consi^te essentially of a closed vessel riirnlshecl with eewagie tnleii
dbcharge connections of a diameter sitit^able to the si;»e of the eject-Of and
the amount of sewage to be pumped. Each of Iheae connections is funiiBh(4^
with a check vnlve {A tind B) opening in opp-n^ite directions with reg»nl t
the ejector. On the cover of the ejc<^tar i^ placed the avitomatir v»lvc J?J
to which is connected the pressure pipe from the air compressing station,!
This valve controls the ud miss ion of air to an exhaust from the ejeciof.|

Air Air
Pip* Fip«

Dhtharr§9

Fio. 304.— The Shone sewage ejector.

Inside the ejector are two ciist-irou bells, T and Dy linked to eiieli i
reverse position^ as hhown, \*y a r<Kl. A bronze rod to which th»l
bolted pajsaes through a stuffing box in the cover of the ejector and conni
by means of links to a Ic^^er with a counterweight, llie rising or falUng
these bells operates the automatic valve E tlirough a rocking shaft coone
it with the ce»ntcr of motion of the lc^*er.

"As sliown, the bells are in fhelr lowest position (the ext4»nt of H
movement being only ikbout 1-1/2 In.), the oompreflaed air iaeut oflf from I

SEWAGE PUMPING STATIONS

681

rjeetor and the Inside of the ejector is open to the atmosphere throuiQ;h the
lutnmatio valve. The sewage tlierefore can flow from the sewers through
tiic inlet valve A into the ejector, which it gnitlujiUy fills until it reaches the
iiTiilrrBide of the bell C, The air at atmospheric pressure inside thia bell is
then enclosed, and the sewage continuing to rise around it, itd l>uoyancy
throws the system of count-er weight and IjcHs, etc., out of equilibriunu
l*he holb? consequently ri«e ttnd the automatic valve is thrown over, thereby
iWing the connection between the inside of the ejector and the atmosphere,
,nd opening the connection \sith the compressed air. The compressed air
automatically admitted into the ejector presses on the surface of the
driving the wht»le of the contents before it through the bell-mouthed
at the bottom and through the diHcharge valve B into the iron sew-
age discharge main. The sewage can only escape fnira the ejector by the
lischarge pipe, as immediately the ejector is filled the inlet valve A falls on
rU seat and prevents the fluid returning in that direction.

**Thc sewage passes out of the ejector until its level falls to such a point
Ihat the weight of the sewage retained in the bell D, which is no longer
supported, is sufficient to pull it ilown together with the upper bell and the
parts to which it is connected, thereby reversing the automatic valve and
fetuming it to its original position. The result of this action is first to cut
i>ff the supply of compressed air to the eject«jrt and then to allow the air
Vrithin the ejector to exhaust down to atmospheric pressure. The discharge
valve B then falls on its seat, retaining the liquid in the sewage discharge
pnain; and the sewage flows through the inlet pipe into the ejector once more,
fajtf 00 the action goes ou n& long as there is sewage to flaw and compressed
^plo drive. '^

I The first Shone ejector installed at Worcester, Mass., was located at
•the sewage treatment plant, where it w^is used for lifting sludge, which
jflowcd by gravity from sedimentation basins to storage basins, from
whioh it was conveyed to the filter yiresses. This ejector has a capacity
of 500 gal. per filling and u provided with supply and discharge pipes 12
in, in diameter. ThiJ* apparatus was selected for this service because
of its ability to handle sucaesafuUy unscreened sludge* and has rarely
been Btop|»ed by obstructions.

The Lake View installation, the tlxird in the city, consists of a power
liouse supplying compressed air to five Shone ejectors^ which lift the
iewago from a residential district having a population of about 1000,
the flow amounting to about 20,000 gal, per day. This diistrict is lo-
cated on a side hill and is divided into three sections, low, intemiediat©
Md high level districts, each served by an ejector station. That
serving the lowe^st raises the sewage about 50 ft. to the setrond station,
nrhich, in turn, ratscH this sewage together with that from its ow n tribu-
tary district to the third station, the iulermediate lift being about 70 ft*
The thin! station lift*<j the combined flow from the low and intermediate
diatrict**, together with the flow from the district tributary to the high
level station to the summit, some 65 ft above. The total lift of the

d^^WUMi

682

AMERICAN SEWERAGE PRACTICE

three statkxis is 189 fL The geoeral arnuigement of these jetton
and the tribaiary scwct distrietB is bhown by Y\%. 305.

The garner {dant oonastB of two compreaBors, each driren by a 15 h.p.
deetric motor. The discharge pipes lead to a steel reeorer from whidi
the air passes through a wroti^t iron main to the several ejectors. The
lowest ejector has a capacity of 150 gaL and the other four hare capai&-

Detoil cf

Ejector Station

Ho.2.

Cof'Tpni^ied Air Pfpea

Fig. SOo. — rfhone sewerage s\-stem, Worcester.

ities of 100 eal. each. Xumber 1 ejector well is made large enough so
that two ejectors can be acommodated when the flow oi sewage be-
comes large enough to make ad«litional machiner>* necessary'. CloB«e by
each of the ejector wells and connected to it is an underground concrete
storage tank, having a capacity of about 30.000 gal. These are
necessary' to proWde storage ior the sewage in case an ejector faib to

SEWAGE PUMPING STATIONS

683

S, at ,

was 1

or

its I

operate. The force rimins consist of 2400 ft. of S-in., and 2140 ft.

of lO-in. cast-irou pipe*

The cost of thiH iiistaUation was approximately as follows: Ejectors,

92950; machinery, $1421; air and force mains, S8555; ejector welLa

Wkiid storage chambers, S5587; total, $18,513.

A tfist of this installation was made on March 20 and 21, 1906, at

vrhich time it was found that the efHcieney was about 17 per cent, h.

tjpUD the electric cmrent delivered at the switchboard*
I The cost of labor at that time, per million gallons raised 1 ft.,
■about f 0.68.

While this system baa the apparent advantages of being automatic

and of not requiring; that the sewage be screened, it is found inpractl

that considerable attention in re(|uired to keep the apparatus in good
|V'orking order, particulary during the winter, when there is a tendency for
It he slifliug valve to freeze. Little adjustraent is necessary but the floats
fehould bo inspected and cleaned at frequent inten^als and the apparatus
khould be kept ailed. At Worcester, it Is the practice to have each
Icjector examined at least once each day. While it has not been found
KDccessary to screen the sewage, thus avoiding the production of un-
Ipleasant conditions in the neighborhood, there has occasionally been
I some trouble due to sticks and other obstructions lodging under the
■Talvc B. When this happens the ejector is filled and emptied in
Iciuick succession, the sewage in the force main passing back tlirough

■ chock valve B into the ejector. This, of course, results in the use of
I largo quantities of air and if the valve is open so that the backflow
I i^ large, the air may be so drawn down that the station cannot maintain
I the necessary pressure and all of the ejectors in the system are thrown

■ out of use.

PtJMPIWG STATIONS

I Pumping stations have been classified in a variety of ways, such aa
I according to capacsitj'^ or nature of prime movers, but there is nothing

■ gained by such an artificial analysis. The authors have accordingly
I prepared brief descriptions of a number of stations, which illustrate the

■ great viunety of ways in which the problems due to poor foundations,
I variable capacity requirements, and different methods of obtaining
Bpower, have been solved* In some cases detafls have doubtless been

■ employed which were due to local conditions and would not be selected
I for a standard design; in studying the various plans, particularly the type

■ of pump drivct thisinfluenoo of local conditions should not bo overlooked*
I Columbus^ Ohio.— A sewage pumping plant built at Cohimbua, Ohio,
■from liie plans of John H. Gregory (Trang. Am. Soc, C. E., voL Ixvii,
ftp. 2.S2) ia Hhown in Fig. 30G. That engineer'a description of it is aftj
IfoUows: I

684

AMERICAN SEWERAGE PRACTICE

*'The sewage is first admitted to a long chamber, serving as a «•*• *
catcher, is screened to remove the coarBer matters in suspension^ and tt» .
passes into the suction well. The screening device consists of two cn^cof^
steel-frame construe tiou, holding removable sets of screens made up of ^/,^
in. square bars, 1 in, apart in the clear. The cages are raised and iomvf^'
by liaiid by a movable screen Ufter hung from a traveling hoist andrunwr^'^i
just below the ceiling of the screen -room above. The auhstructttn
concrete, reinforced at various points. In the substructure of the
room, in which are located the pumps and engines on account of the aticti
lift, the walls are linwl with liard vitrified red pressed brick.

**The waUa of the superstructure are of brick» faced with red
brick outside. In the engin e room the walls are lined with light btjlf-«peckli
pressed brick, and in the screen room with hard red brick. The stone triro-
mmgs are all of Bedford limostone, Tlte ceilings in both rooms are all erf
plaster on metal lath» fastened to the lower cliords of the roof tmeses. TU«
roof is of 3-in. hollow terra-cotta tile and slate carried by steel tnusses aod
intermediate franung.

**The pumping niarhiricry is installetS in duplicate. Each unit constnts of
a Cohimbus, horizontal, four-stroke-cycle gas engine connected by a Mors©
silent-running high-speed chain t^ a horiKontal, single^age Worthington
volute pump with 12-in, auction and 10-in, discharge nosslc«, Tlie engine
b capable of developing 90 h.p. when operating on natural gas having a
thermal efficiency of about 1000 B.t.u, per cubic foot. When riir ' -
together each unit has a rated capacity of 2,2fW,t>00 gal, per 24 hours ?i .
a head of 76 ft,, and when mnning alone a maximum capacity of 2,*hki, i^
gal. per 24 hours against a head of 63 ft. For starting the enLu.^ , tin
equipment includes a small motor-driven air compressor and air t mL

"The sewage is pumped through a 20-in. cast-iron force main t<» a jHunt
about 8180 ft. from the pmnping station, where it is discharged into the
upper end of the Mound St. sewer. The flow is measured by a 20-in.
Venturt meter, the register, chart recorder and manomet^er being placed b
the pumping station. The meter tube is of special construction, and
between the tube and the register and manometer, oil seals are interposed to
keep the sewage out of the latter."

Newton^ Mass*— A pumping station built for temporary service at
Newton, Mass., from the plans of the late Irving T, Farnhara, iUtistratei
a t)^m of plant whore the water end must be at a low elo%*atir r ' n-
tcrnal combustion motors are desired for operaton* It was c *\

in 1903 as an alternative to a verj^ expensive sewer for the sni

of people to be served until the district was developed coi. „...

beyond its population at that time. The sewage was delivereil to a m>
ctdar tank IS ft. in diameter and about 7 ft. deep inside ^ ' ' tiboul
13,000 gal., Fig. 307, The walls were 12 in. thick, on 1 Ung^,

and the bottom was 6 in. thick with a downward slope to a central siunp
about 1 ft. deep. The tank was divided by a 10-in. wall tb'-^M..], ti^^
center into two halves, and an 8 X 8-in. sluice gate at the hot' i?

wall enabled cither side to be shut off for repairs or cleamikg« 1 luj taok

iSl

dfl

Id

3(».-«-*'"*"

.SEWAGE PUMPING STATIONS

685

htui A 5-in. roof about 10 ft. below the surface of the g^round* This was
constructed of reinforced concrete and carried by I-beains.

The pump house was 9 X 17 ft. in phm, 9 ft, 8 in. deep underj^round
anrl 7 ft. 1 in* high above ground. The basement walls were S in. thick,
of reinforced cont^rete, and were strenii^hened by a number of buttresses;
an extension of thin basement, 8 ft. long and 3 ft» wide, serv^ed as a valve
chamber and had independent ventilation. The superstructure had
walb 6 in. thick with a roof 7 in. thick at the ridge and 5 in. at the sides.

The pumping plant consisted of two 3-1 /2-in. vertical centrifugal
pumps operated by two G-h.p. gasoline engines. The oonneotions were

ich that either engine could be used to drive either pump, or both

gincs used to operate either or both pumps. The jacket water from
the ensrincs was cooled in ordinary radiators. There was a check valve
on the diiicharge pipe and a gate valve beyond it, and the discharge pipe
of each pump also had a gate valve. Gasoline was stored in a tank
buried in the ground outside the house. The pumps were started by an
attendant in a water-works pumping plant 300 ft. distant but were
stopped automatically by means of a float-operutLHt device, which cut
off the electric ignition. The plant cost $6700 and had a total capacity,
CO tost, of 400 gal per minute. The total lift was 30.7 ft.

Hampton Institute, Va. — Another example of the facility with which
vertical oentrifugal pumps adapt themselves to unfavorable conditions
of elevations and also of foundations is a^orded by an Installation at
Hampt^)n, Va., built from the plans of Albert L. Webster {Eng* Record^
Nov. IS, 1%5). The sewerage sj-t^tem with wliich it i& connected carea
for the property of the Hampton Institute, where about 1000 people
live. The property lies low and the ground water elevation is about 2 ft.
below the surface during most of the year. The pumping plant was
located on the bank of a small creek, where the ground was so soft that
the pump well was built with the help of a steel caisson, Fig. 309. In
fiinking the caisson, the bottom plate was omitted, except the ringsupport-
ing the brick lining. The latter was not put in until the pkte had been
riveted in place after the caii^on was simk and the tightness of the entire
shell tested and all kiakft oalked. The shell was battered l-l /4 in. to the
foot on its outer face to give additional resistance to the upward hy-
drostatic pressure of the ground water, but as this resistance was small
the brick pump house over the well was built on a square grillage of
heav>' I-beams resting on the walls of the latter and cantilevered over
them to form a square foundation.

The pump well is provided with a division ivall curved in plan so as to
provide a dry well in which the pumps are located, and the wet well has
a heavy partition wall rising half way to the engine room floor. In each
half of the wet well formed by this partition there i» a float chamber
formed by a thin reinforced concrete wtvll with a sjoreened opening at the

686

AMERICAN SEWERAGE PRACTICE

SEWAGE PUMPING STATIONS

687

ott-om. All pipes through the walls of the pump well onter through

ron sleeves with two circular flanges, one on the outer end which i» riveted

^nd calked to the sheO and the other inheddcd in the brickwork to form

I cutoffp The iron pipe passing through each of these sleeves was calked

I both ends by means of yarn and lead, like a cast-iron pipe joint. In

the pumps should be out of commission for any reason and the

je should rise in the wet well, there is an 8-iii overflow pipe at about

titfmaf9dH.W
in River

Sectional Front Hcvatton .
Fio. 308> — Pumping station at Newton.

I ground water level, which will allow the sewage to pass into a creek
ft. distant.

Each of the 5- in. centrifugal pumps is driven by a 15-h.p. 3-phase

i-volt 60cycle induction motor, started and stopped automatically by

lie aotion of one of the floatii previously mentioned. A r<xl rising from

float moves a lever connectCHl with a device acting like an elevator

itroUer* Current is obtained from a local electric railway company.

688

AMERICAN SEWERAGE PRACTICE

c

o

0
>

c
3

T

0

0

c

0

o
o

SEWAGE PUMPING STATTOXS

fl

obtaining steam from the neighboring power house of
institute has been installed as a rescrv^e; it drives one of the pumps

rough a belt to a pulley on an extension of the armature eiliaft of the
iTiotor. The combined efficiency of the pumps and motor on abort runs
Tanged on test from 52 to 73 jxiT cent.^ averaging 63.7 per cent.

The pimip well is ventilated through a 10-in. pipe running to a ventilat/-
ing stack, which also vents the tanks to which the sewage is pumped;
these tanks and the shaft arc described later in this chapter under the
head of yturage Basina.

Chicago, m.— Sewage pumping at Chicago is carried on in two largo
stations which are unique in design, owing to the peculiar plan of that
city's sewerage system, involving the discharge of crude sewage into
the branches of the Chicago River and the reversal of the natural di-
rection of fiow in the South Branch, so as to carry the sewage to the inlet
of the drainage canal. The 39th Street pumping station^ the lirst
which went into operation, w^as built to pump sewage from a large
intercepting sewer along the lake front through a 20-ft. gravity conduit
to a fork of the South Branch. In order to dilute this sewage so that it
would cause no offense in the ojjen channel of the river after leaving the
conduit, arrangements also had to be made to pump along with the
so wage a large amount of water from Lake Michigan, so that two sets of
pumping machinery became necessary.

The general arrangement of the station is shown ■ 10

{En^. News^ Sept. 10, 1908). Of the centrifugal sewage i _ _ , vo

have a capacity of 75 cu. ft. per second against a head of 24 ft., and
handle the dry- weather flow; the minimum flow in 1908 was about 90
cu* ft. Each of the two larger pumps has a capacity of 250 cu. ft. per
ftpcond against a head of 13 ft,; they were installed to handle the stonn-
Crater flow, and when this is being done a lift gate at the end of the chan-
nel is closed so as to keep lake water from the pumps. Ordinarily this
gate is open and the lake wat^r is prevented from reaching the dry-
weather p\impe by a gate acting like a tide gate.

While the arrangement of the channels leading to the large centrif-
ugal pumi)«5 ii5 fiUt*ii that they can be used to pump flushing water from
the lake into the Outfall conduit, this service is ordinarily performed
imps, each rated at 606 cu. ft. per second. The maximum
. hich these pumps were designed to operate was 7 ft.; it is
possible at certain stage-s of the lake to supply water by gravity from the
Jake to the conduit > for which purpose a special channel was provided,
closed at it« entrance by a gate operated like one of the leaves of a lock
gate.

The centrifugaJ pumps are operated by horizontal triple-expansion
engines and the screw pumps by vertical triple expansion engines.
There are six 264-h.p. water-tube boilers to supply steam.

44

SEWAGE PUMPING STATIONS

691

Dayton, Ohio. — The sewage pumping stations in Dayton, OhlOi
attracted considerable attention from designing engineers for f^ume time,
on account of the rather unusual control appiyatus with wliit^h three of
them were provided, which has been stated by the local authorities to
work very satisfactorily. One of the four stations has two 20-h.p.
ii-phase, 60-cycIe motors geared to vertical submerged centrifugal pumps
with a capacity of 2500 gal. to an average lift of 20 ft. The other stations
Imve two units each. Kach unit has a double-suction vertical submerged
4500 gal. centrifugal pump direct-connected to a 40^h.p. 3-pha$e 60-
e>'clc 20S0-volt motor. The starting apparatus referred to is contained

Fio, 311. — Automatic pump controller, Dayton.

in these three stations. As described in Eng. Neu% April 30, 1908,
it is worked primarily by float-operated valves in a cylinder wliich receives
wat^r from the city mains. A piston in tliis cylinder raises the level of
Ml ftUto-«tArter to the ** starting" position, and at the same time rotates
an arm carrying a heavy counterweight, as shown in Fig. 311. About
the timt3 the motors come up to speed this counterweight reaches a dead
eeater fiosition and falls over, throwing the lever on the starting panel
t<i the *'nmning** position* As the sewage is disposed of so that the
level fttlla ti> a pre<li trriniued point, the float valves operate the piston
to give a reverse motion to the counterweight arm, wliich in turn brings

panel to the **stop'' position, cutting off

692

AMERICAN SEWERAGE PRACTICE

current from the motor. The electric equipment of the three stAtiooa
was furni.shcd by the Westinghousc Electric & Manufacturing Co,

Waltham, Mass, — The sewage pumping station built at WaiUham,
Mass., in (907^ from the plans of City Engineer Bertram Brewer, ha^ a
storage well 19 ft,l in. diameter and 17 ft» deep, with plain lO-in. concn?te
walls, constructed by holding up the sides of the pit with 4-ft. poling
boarcla braced by ribe of 4 to S half-inch boards nailed one o\« '
other to complete the circle. The well is about 50 ft. from an adj »
river and below its level except for the upper 2 ft,, but It is entirely
waterproof, owing to the care taken in selecting and mixing the material
and to the use of hydra ted Ume to increase the impermeability of the
concerte. The plant consists of two 4-in. vertical centrifugal pumps
direct^connected to 15-h.p. vertical motors, which are started and
stopped automatically by means of a Westinghouae controller. The
sewage is scroenod through a basket screen and enters the pumjis
through very short suction pipes; the pumps are in a dry well a* shown
in Fig. 312 {En^. Rec^d, March 7, 1908). It was stated io thai
journal that the plant cost $7000.

The automatio starting and controlling devices for the alternating-
current motors of this plant consisted of the usual float and eotmtcr*
weiglit operating a sheave or hollow drum, a weight on the eiid of a
lever, two spiral springs, and a pawl arrangement for regulating tbe
action of the springs. The operation of the apparatus was dmcribed as
follows by Mr. Brewer in I he article prenously referred to.

** A sheave is mounted loosely upon a shaft; an iron ring, cast on the Jiide

of the sheave, has a slot ctit in it tlirough which passes the arm c 'o

weight. This weight-arm is also free to move fin the shaft. Th* ^»

sheave-ring is just long enough to allow the weight-arm to f:^

tical to the resting place, an arc of 125 deg., so that when the i

through a distance of 125 deg. tlie weight will be lifted to Uj« p

and allowed to fall an equal distance in the opposite direclicTi.

weight falls, the weight-arm engages two spiral sp^'ings, which at€

loosely around the shaft. These in turn rest against a casting wbu

screwed to the shaft, but which is prevented from turning by a pawl, whij

is held by notches in the main shaft. The weight-arm compr

springs, and then trips the pawl and the spring move^ t-o the ni^xtt

The pawl is tripped three times during the downward mf>ti«M

and each time it is trippe<l it iillo\%^ the shaft to be turned a <

by means of the eotnpreaeed springs^ and the shaft in tuniing ojjoraics tbt

sut4>-s tarter, throwing it througlt the three notches to tin fnW

Wlien the weight falls in the opp<jfiite direction, the a«i«>*' r|

to the off position. The time of the fall of the v '^^t •« "■ "^t

pot, aituatefi at the end of the weight-^lrum I

^'The flout mechanism, while ver^ • ^

siderable annoyance at first, owing t

SEWAGE PUMPING STATIONS

%M

AMERICAN SEWERAGE PRACTICE

inseparable from an unhealed, isolated plant. The control rope wns
necessarily long and its length was raat^rially alTected by changes in tempera*
tuTc, awd when too hx»8e or loo tight wovild not operate the controller. The
difficulty was overcome by inserting a heavy spring in this control rope. ^
This difficulty surmounted and the weights of float and counts- weights
made ample t-o furnish the necessary power to lift the weight-arm on thffl
controller and overcome the considerable amount of friction in the apparatui I
itself, the operation has proved reliable under the tr^'ing conditions of &
severe winter/*

Saratoga, N. Y, — lo the sewage puniping plants at Saratoga, N, Y,^
and Hudson, Mass,, designed by Frank A. Barbour, time-limit relay
were installed to cut out the current automatically in case of stoppa^j
of the motors or burning of the switches. The floats were so set that
the first pump started with tlie sewage at a certain level, and if the ia-^
flow was greater than the capacity of tliis pump the sewage rose to th
level where it operated the float governing the second pump. Tli
second pump^ coupled to an alternating motor, ran at a constant speed
and, starting against a closed check with no discharge, developed tha
necessary pressure to lift the check and begin pumping. The capacity
of each unit at Saratoga was 1500 gal. per minute, with one pump work^
ing against a head of 28 ft.; 1200 gah with two pumps working i
a head of 3S ft,; 1000 gal. wnth all three pumps working against a
of 42 ft.

Hudson, Mass. — At Hudson, the pumps were set in dry wells below tb
height to which the sewage rose m the adjoining wet well, with suctioa
laid tlirough the dividing wall into the collecting well. The i ii

was to have the pumps accessible for repairs and ready primed w ul

rise of the sewage. Their total capacity was 500 gal. each with two UQitaf
working against a total head of 35 ft. Considerable trouble was expe
enced at this place with the stuffing boxes and leakage of air into
pump casings. As a result, the pumps were frequently run submerg
in water. This is mentioned to show the importance of insisting upon
having a tight pump casing when the pumps are to be pkced in a <
well.*

Summer St., Boston. — Difficulties like those mentioned in the
of the Waltham plant, are ovei-come in the Bummer St. Station, Boston

1"Tq prevent air leak&ge ihrotigb the atuffins box on the xui^tion bead nf Uii^ pamM
th«r« is provided a gland cago within the stuffing box, on each sidv of wliicH tlivr* Aliauld
be placed about three riass of fraphito packing. On the ouMide of tkt*- *uitT<,u^- t.fi< wi||
be found a 1/4-iti. pipe tap, which oonnecU to tb» gland cage. TUen< > nit*

run from the ditcbarge of the pump and led to the ly4-in, pip« tap, thii « v%m

aeal in the stuffing box and preventing all air Ic^akagv. The gluud •bould W ruu ju«t t
loose aa poBBiblo. a« otherwise the pac^ktng is liable to euC the shAfL A itTinlt iitnt>»inf *
leakage from the vtuiiinK box docs no barm» in fact it i« ivn advantag<t| n
packing from heating and at the tame time keeps the tbaft 1uhricat«d." i
ington. For pumping anvtitkKe the lAn, pipe tbould cottitpft wHh a eir
ILS it might beoome quickly clogged if connemted with ibe diM'hargu pijH

SEWAGE PUMPING STATION:^

695

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use of a controller without flexible cords, as shown in Figs. 313
L The copper float \& cUimped to the end of a vortical rod and
kd falk in an 8-in, cast-iron pipe, jp ving it a range of motion of 3 ft.
, distance above the float a hea\'>^ rubber ring is attached to the
ind the pressure of this ring against its seat, the cap of the float
&r, is suflicient to make a tight joint and prevent sewage from
\g from the chamber.

station, which was designed by C. 11. Dodd, under the general
m of E. S. Dorr, is shown in
4. The station is underground,
he exception of a narrow con-
m trance hood rising above the
k just inside the curb line. The
\ enters through a 24-in. iron pipe
ating in a sluice gate* There is j
Ben, because the designer con-
that a 10-in. pump would pass
If Ukely to reach it through
irers. Provision has been made,
fer, for freeing the impeOer from
rithout dismantling the pimip,
pies being pro\ided for the pur-
The sewage is passed through a
I formed by brick side wallB
; diagonally across the gate
er, and then enters a wet well
ng, 6 ft, high and 2 ft. wide.
g enough to feed the sue-
three pumps, but for the pres-
wo have been installed* In
the three 10-in. suction |
inections are made from the
U to the float wells, previously
and also to a sump from
sewage and drainage are
a water jet ejector. Each
its own switchboard, fur-
by the Cntler-Haninier Com- , . , ...
The air in the pmnp room is drawn out through a blower which
t up to the entrance hood, where it esca|3cs tlirough a grating m
of the iron door bv wiiich the entrance shaft is closed. Ihe
m carried on a floor supported by 6-in, I-beams; the structure
^ i^ built of reinforced concrete carriqd o» r»^»-
\the details of thi. station is a babnced back-water gat..,

Fio. aia.-^FI^a^ and float welU
Boston.

696

AMERICAN SEWERAGE PRACTICE

Fig. 315. These gates are not designed to act like tide-gates, but are
placed on the discharge pipe to prevent water from backing through
them and causing trouble when the pumps are taken apart for repair.
In order that they may be as sensitive as possible a cast- iron ball is held
at the proper position along a rod running up from the gate to counter-
balance the latter. It can be adjusted very closely and held in place by
a bronze screw, and offers less resistance to the flow of sewage from the
discharge pipe than the ordinary type of heavy flap valve. A pair of
lugs on each flap and scat permit them to be bolted together when the
discharge pipe is to be closed to protect workmen while the pump
casing is opened.

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Fk;. 315. — Hnckwator punii)-di.sfhargc gates, Boston.

Another detail of this station is the cover of a manhole, which had to
l)e larpe enough to permit niaehinery to be lowered into and removed
from the enjijinc room. For handlinj? the machinery in the room there
is a 7-in. l-l)eam in the roof, from which a hoist is suspended. This
runway extends to tlie manliole which is 3 ft. 9 in. wide and 5 ft. 3 in. long.
Inasmiicli its it will very rartrly he entered, it was considered desirable
lo olTer as little obstruction to travel as i)ossil)le, and accordingly the
Boston standard rectanc:ular frame w:u< chosen. In this ca.sc, however,
it was also desirahle to prevent moisture from accumulating below the
iron cover iind dropping into the portion of the engine room below it.

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SEWAGE PUMPING STATIONS

697

This was not unlikely to happen when the weather outside was very
eold, for on such occasions the temperature in the pump chamber might
be 2^ or more wtirmor than the manhole cover. To overcome this
_drippmg a east-iron rabbet was placed in the top of the manhole masonry.
, wooden cover consisting of 4 X 2-3/4'in. timbers with 2 X 4-in, battens
tviM Imd <jn this rabbet and the edges all around it calked and pitched so
aa to make a perfectly tight cover, Fig. 316. Between it and the bottom
c> r 1 - iron manhol e cover there is a considerable air space, which has

]•' i any gathering of moisture.

Large Station, Boston. — A much larger station, Fig. 317, built in the
same city in 1914, from the plans of the same designer, is probably the
largest sewage pumping station with automatic control down to the
time of its construction. The building is 65 X 40-1/2 ft* in plan; the

Fig* 316, — ,\nti-condensation manhole cover, Boston.

I' L r nirm i^ nuich Urger. Along one side of the building extends the
motor room^ and in order that* machinery may be moved into and
out of it reiidily there is a large doorway at oni? end and a return in
the curbing, so that a motor truck can be backed into the building for
flome distance, the floor being strengtliened for the purpose. A trans-
fornier rciom in one corner of the building oan be entered only through
an outj^ide door, the keys to which are lu the ponaoasion of the
yees of the local electric light company, the sewer service having
. u>pon8ibilit>' for the care and maintenance of the transformers.
Adjoining the transformer room is a small room» also entered only
through an outside door, affording access to a manhole leading to the

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SKWAOK tUJLtPlSa STATIONS

^a^Hk ofa amber* The remainder of the ground floor is occupied by an
aSc« wttb a large store closet and by a shop.

The station contains three loO-h.p* motors^ each driving a 3^in.
cetitnTugal pump, and a 75-h.p, motor driving a 24*in. pump, Fig. 318*
The sewage enters the station through a screen chamber, provided
with a screen constructed according to the details shown in Fig. 319.
The screen k in twelve panels, each 15 in. wide, and 8 ft. 3/4 in, long.
The general arrangement of thi^ screen chamber is shown in Fig. 320.

The pumps are controlled by a float in a well of the type illustrated
In F|g. 313, one well sufficing for all pumps, the switch mechanism
throwing into ser\nce one pump after the other as the level of the
aewage in the suction eliamljer rises. The electric devices for this
purpose were i ' by the Cutler-Hammer Co. There is another

float well ill ih a which ojx'rates an automatic recording gage»

of a type in use in several places on the Boston sewerage system. It
was designed by Mr. Dodd and has a pen moved vertically by the
float rod o%'er the surfttcc of a chart which is revolved horizontally
by clockwork.

Thn small pump has its suction run into a sump 3 ft. lower than t!ie

remainder of the suction chamber, so that tliis pump can be used to

the station down to the level of the pump room floor. Below that

the drainage is removed by hydraulic eductora with suctions

in small cast-iron sumps in the concrete floor.

The positions of the 2 1 /2-in. brouxe nipples and gate valves for
blowing off eiich pump casing and the bottom of each liydraulic gate
Valve are indicated in Fig, 318. The hydraulic gate valves are con-
net'tfid by 1-in. pipe with the street mains. The end of the discharge
pipe has a large backwater gate of the type illustrated in Fig. 298.

Wa^iinCton^ — ^The sewage pumping station at Washington, D, C,

dtiiglied by ;\sa E. Phillip*^, superintendent of sewers of tlie District

ol Columbia, has been nmch praised by engineers, European as well

IM Axnerican* The general arrangement of it and of the conduita lead-

iilK to and by it, which fonii one of its most interesting features^ is shown

tn Fig, 32I» frrim Eng, R^nml, Aur. 28, 1908. At this station the entire

Ci^wage of the rily L- |nanjK'd I liiuuKh a pair of <KMn. piptt about 18,000

ft, long to a point in the Potomac River about 800 ft. from shore. The

large conduits on either side of the i^tation discharge into the .\imco8tia

Kiver, on th«* bank of which the station stiuids, the storm water from a

eonii'l 1 of the city. A part of this

itCTiT while another part must be

. *«5d at certain eriages of tlie Hver*

I lie Tiber Creok and Jersey Avenue high-level intercepting aewer

fioiitfi^M along the fast eiide of the pumping station. Before it n^aches

the fltntion its lower portion haa a eeeiion 14 ft» wide and U ft. 3

•^ ^"^ -^ ' - - - -

SEWAGE PUMPING STATIONS

703

high, with a cunette, or dry-weather channel, diverted near the
tation, into a tWt. circular conduit, into which the east side intercepter
-1/4 ft. in diameter, also discharges. Beyond the point where the
^-weather channel is led to one side, the Tiber Creek sewer con-
aues as a twin section, each channel being 12 ft. wide by 10-1/2 ft.
dgh» the invert level with the berm of the cunette section* On the
rest side of the pumping station the B Street and Jersey Avenue
sewer extends. This also has an 18-ft. ounette section 16 ft,
before it reaches the pimiping plant. Where the dry wealher
ftnnel, or cunette, is diverted to one side, the main sewer becomes a
in section, each side being 12 ft. wide and 10^1/2 ft. high. All these
vers are built of concrete with a lining of vitrified brick on the
ortiou of the invert subject to greatest wear and red brick on the
^ther parte of the invert over whiah sewage is likely to pass at
»me time.

The diversion conduit for the dry-weather sewage from the B Street
ver, is 6 X 6 ft, in size and joins the 5-ft, circular conduit from the
Tiber Creek sewer at a gate chamber containing two 84-in. sluico gates.
Qe of these admits the sewage, during the normal operating conditions,
into a aodimcnt chamber 50 X 104 ft. in plan, having a groined arch
of carried by columns 3 ft. square and 16 ft. apart in the clear. This
phiimber extends partly under the pumping station and is large enough
reduce the rate of flow of the sewage to considerably less than 1 ft.
Oer second. The sediment which is collected in the chamber is re-
aoved in 2/3-cu. yd. buckets. These are brought into the chamber
^n cars run into it on an industrial track laid on the floor, and are filled
ty hand. The cars are run under a hatch in the roof and the buckets
re lifted from them to a troUey on an overhead track at a much higher
jllevation, by which they are transferred to the river, where their con-
ents are dumped into a barge. The overhead track runs for part of
Bngth through an 8 X 8 ft. passage or iunn*}!, which is also used
part of a system of ventilation worked out so completely that no
offensive odors have been detected about or in the station.

The sewage is drawn from this chamber into an 8-ft. conduit having a
check gate and a twin screening chamber. This screen cha mber is 30- 1 /2
ft* long, 20-1/2 ft, wide, and divided into two equal portions, each with
two screens of 3/4-in, rods on 2-1/4-in. centers, operated by hydraulic
flinders and counterweights. The trash from the screens is removed
through a branch connection with the conveying and ventilating tunnel
f just mentioned. The sewage passes thi-ough this screening chamber into
a suction chamber, from which three centrifugal pumps draw their
apply. These lift the sewage into a 16 X 22 X 40-ft. siphon chamber
^t the head of an inverted siphon under the Anacostia River, which
I the first part of the outfall sewer. The gate valves on the head

704

AMERICAN SEWERAGE PRACTICE

of the two pipes formiiig the siphon have their seats on the down
side cut away so as to leave no bottom slot in the valve bodies in wbid
sediment can be collected. In case the sediment chamber is out of
sen^ice for cleaning, a by-pass delivers the sewage from the pite ehjuitber
directly to the pumps. The latter are known as Class I piuupfi, to
distinguish them from two of smaller capacity installed for a sj^ecial
purpose* The sewage from a small low-lying district served by «
separate system^ independent of the trunk and intercepting sewen,
is delivered through a 3-1/2-ft. sewer which has no connection with the
settling basin, but runs directly to these smaller pumps known as Class
II, an arrangement necessary to obtain proper hydraulic gradients.
The pumps discharge the sewage into the siphon chamber or thrott^ aa
emergency by-pass into the river. There is a screen chamber in tiie
suction conduit of thei^e pump«, and a by-pass is provided ao that cither
Class I or Class 11 pumps can temporarily be iised for the service of
the other.

The storm water delivered through the Tiber Creek sewer pa88<*s
directly into Anacostia Creek through the tide gates on the bulkhead,
as indicated in Fig, 321. The storm water brought down by the B
Street and New Jersey Avenue sewer must pass first, howc * a
storm- water chamber, 160 ft. long, 3t)-l/2 ft. wide and 16 ft. In , g

a roof of concrete arches carried by I-beams. Along one side of this
chamber are openings fitted with screens of 1-1/2 in. wrought-iron pipeea
4-1/2-in. centers, placed on an inclination of 1 to 6. An elevated plat-
form between the walls of this chamber and the pumping <- ' i^
been constructed for use in cleaning the screens. When th^ u

of the water in the river permits, the storm water passes directly through
this chamber into the river. When the latter is high, however, tide
gates prevent a backflow into the conduit and the storm water tlmt
comes down is pumped from the chamber into a 15-ft, discharge condtiit
at a considerably higher level, eight pumjie being provided for thia
especial purpose. It will be observed that it is also possible to utilise
the Class I pumps for handling some of thia storm water^ ia ease of
emergency.

The pumping station has at the land end a three'«tory 75 X 13
section used for office and shop purposes; in the middle tiiere is I
90 X 170-ft. engine room* and on the river front a 60 X l2lWt,
house with elevated coal bunkers. The Cbiss I pumps am three
number, each driven by triple-expansion enRine^ and rated at 100 «t
ft. per second to a height of 27 ft. One tif tho'ii ia a reserve^ Tlirrt %x^
two Class 11 pumps, one a triple of a capj^^^^^^ ^^' '^"* "*» ^* ^-^
raised to a height of 20 ft., and the other a
The htorm-water pumps disc!
of raising 100 cu. ft. pCT leOOii

SEWAGE PUMPING STATIONS

705

particularly effective at their usual liit of 3 to 8 ft. Owing to the
ct that they are in oi)eration only a portion of the tioie, thoy are
Iriven by compound engines. All engines but one are of the horizontal
without ilv-wheel, direct-connected to a vertical punip shaft,
developed by the AUia-Chalmers Co. for one of the Boston sewage
jumping stations. The Washington pump setting differs from that of
arlier stutions in the omLssion of separate chambers for each pump,
Washington the entire basement of the engine room serves as a
t dry well. The only vertical engine is the compound driving one
: the Class II pumpfl» a unit which hatl been used during the construc-
tion of the station, and w^as in good enough condition to be installed aa
. reserve in the permanent plant.
The engines are supplied with steam by six water-tube boilers, each
275 h,p.) with automatic stokers, fuel economizer, complete mechau-
coal handling machiner}% and the other accessories and auxiliaries
a hif^h- grade power plant,

Baltimore.— The Baltimore sewage pumping station is provided with
main engine room 180 ft, long, 54 ft. wide and OS ft. high from the
anient floor to the chord of the trusses. Eventually it will contain
Ive pumping engines, two drainage pimips, a 20-toh electric crane, an
iectric switchboard, and valve-s and piping. Three pumping engines
ive been installed, whicli were built by the power department of the
iethlelieni Steel Co. These are of the vertical, triple-expansion, crank
^nd fly-wheel type, Fig. 322, rated at 27,500,000 gal. in 24 hours against
t head of 72 ft, when the speed is 20 r.p.m. The pump has three single-
acting plungers, 40-1/4 in. in diameter and 60 in. stroke, and the valve
ambers have ver^^ large clack valves shown in Fjg. 30L Each engine
\ rated at about 400 h.p. at normal spead. On test the average duty
ras 165,(X)0,000 ft.-lb. per lOOO lb. of dr>^ steam, with an average slip
^f about 3-3/4 per cent. The drainage pumps are 12-in. centrifugals
liriven by 40 h.p compound condensing engines and have a capacity
3000 gal. per minute each. They draw their supply from the
lerdrains of the low-level sewers, and discharge it tlu-ough the
cindensers of the sewage pmnpfng engines or directly into the harbor.
Jetwecn the engine room and the boiler room is a screen chamber
rhere the sewage is first sent through movable coarse stTeens.and
lien through finer fixed screens over the entls of the suction pipes.
The boiler room is 94 X 50 ft, and contains space for five water-tube
filers, each of 265 h,p. At the present thne three have been installed,
gether with one of the two economizers for wduch space is furnished,
ad the ooal and ash handling maehinery and various auxiliary
aachiner>%

t Providence. — The sewage pumping station at Providence, R. L, ia
rticularly. interesting because of the rec-onstruction of the plant in
I

■

706

AMEBIC AN SEWERAGE FHACTTCS

10 11. Th€ original plaut contained HoUy engines installed in 1896^
of tho direct-acting triple expansion condensing type, each unit havmg

Fig. 322.— Interior ol Baltimore punipuig stuUua

two fly-wheels* The pump pluxigora were 42 in* in diameter
long. The sewage valves were of the weijJthtod olarl i\ i«.
rubbor diBk 5/8 in, thick opeaing 1-7/8 in. The tl*

SEWAGE PUMPim STATIONS

707

» oauaeci much trouble. The valve seats were bushetl with bronse
Mame badly worn« so that the valve disks had a short life and
pntimes became broken off. While repairs wore being made heavy
tiis sometimes ocourfed m summer, resulting in the tioodin^ of the
parts of the ntation with «torm water and sewage. These oondi-
I were considered so unsatisfactory that it was finally decided to
idou the old wutrr end entirely and tn substitute for the plunger
unps under each engine^ two centrifugal pum|xs driven by regies from
I two fly wheels. Ropes were chosen rather than belts, bucause of the
Hibility that the pump wells might be flooded, which would cause
•^lipping of the belts. The reconstruction was accomplished
'^ circular rings to the flywheels, each containing 11 grooves.
*he old water end was removed entirely, leaving ample room for the
fo centrifugal |>umps, each of the capacity of 15,000 gal. per minute
lainst a totul operating head of about 31 ft. The capacity of each
ngine has been increased alicnit twenty per cent, by this change,
totiU cost of the reconstruction of the thre« imits being about
^,000.

Bataviap N. Y-— There is a small steam driven station at Batavia, N. Y.,
where a horizontal l(K)-h,p. Corliss engine drives a vertical centrifugal
Limp riited at 470 gal. per minute and two rated at 1050 g^iil each against
totttJ head of 54 ft. City Engineer Robert L. Fox informed the
iithofs that this system of driving was accomplished by rope drives
twecn the engine and the main shaft and between the shaft and
ch of the pumps. The quarter twist necessary^ to chive a vertical
Jt from a horizontal one was readily accomplished with the Dodge
' trtttvsmlssion system.
Detroit -^The pumping station at Detroit, built in 1912, is ofte of
l{tt(*st steam-driven plants and has proved so satisfactory In opera-
according to hiformation furnished by City Engineer R. H. Mc-
dck» that no changes in any details would be adopted tn a new
ation for the same srrvice. The external appearance of the plant has
mi favorably critnLsetl and is shown in Fig. 323. The building ia
ft. long and .50 ft. wide, constructed of buff brick with terra-cotta
Immmgs above the grey sandstone base courses. The steel roof sup-
brU reinforced concrete slabs on which red tiles are laid, and there
-mitor for ventilation. ItLside, the wainscot is of white glazed
^ with gray faced brick above it. Th*^ floor is paved with red
fe. The doors and window sash are steel.

. 9-ft. »ew(T enters one corner of the building and discharges mto a

^^11 m ft. long and 0 ft, wide, running ulouKside the pump weU.

^n pipa^ leading from this well have hydraulieally ^l^^'''^^^'^

-.-^ .. at the end.s and a 24-in. vitrified pipe line leads from tne

H lo the ba.^e of the stack for ventilation. For handling the dry-

708

AMERICAN SEWERAGE PRACTICE

weather flow there is a 24-in. centrifugal pump of the vertical typegj
with a I oO-h.p. motor to operate it. The sewer ha« such a large capacitj
thai it alTords enough storage during dry weather to enable the motor
to be shut down during the period of peak load carried by the clertric
company furnishing current. The storm water is handled by a pair of
42-in. vertical centrifugal pumps, each rated at KX) cu, ft. per sccoud
The t:3niall pump is rated at 30 cu. ft. against the same head. UooD
is loft in the station for the installation of another large eentrifugah
Each of these storm-wat^^r pumps is driven by a horizontal comfwund
condensing engine rated at 542 h.p, with the cyMnders placed at rij^ht
angles with each otlicr. The pumps are located in a dry well w^hich is
ventilated hy means of an exhaust fan. The thrust bearing is ^hmt
half way up the shaft from the punip to the crank, Steam is furnished
by two :iOO-h.p, water-tube boilers with automatic stokers. The boili

Fig. 323. — Screen chamber and pumping station, Detroit,

Bettings are finished with white enameled brick. About 200 tons <
coal can be stored hi bunkers formed by a wall 12 ft. high and 8 in. thidCt
running along one side of the boiler room. The stack is 120 ft. high
and 5-1 2 ft. in diameter.

Lebanon, Pa.— The sewage pumping plant at Ijcbanon, Pa., dejsicnrii
by James H. Fuertes, of New York, has an im usual system of control,
which is now (1914) being duplicated at Dallas^ Tex., in a plant dcsigniLMl
by the same engineer, the original installation having ; ' !yj

satisfactor>' in scrv^ice. The pumping plant wjws built to
to trickling filters under a sufficient head to secure satisfacton* njsiiiq
Two pumps are ascd, each a volute centrifugal with H-in. sustion
6-in. discharge j>ipes, a closed impeller, and guaranteed t« ddrvtsr 1,0
000 gal. in 24 hours through a total lift md to ovorcoiDe t.

SEWAGE PUMPING STATIONS

709

[lift of 8 ft. when starting in operation. They have horiiiontal shafts
[imd are directly cormeoted to G-pole induction motors wound for
IS-pha^e, 6(Njycle, 220-volt ourrent. Etvch motor was retfuired to be able
[to stand an overload of 25 per cent, for 2 hours without injury, Stich
Ipuniping units run at constant speed, and conseciuently some method of
^controlling their operation was necessary^ in order to carry out the de,sire

the designer to send the sewage to the trickling filters from im Imhoff
' tank at tlio same rate at which it reached the sewage treatment works.

It will be seen from 1 lie diagram, Fig, 324, that screened sewage is
I delivered into the Imhoff tank, from which it is drawn by the pump.*?
land diiKrharged tlirough an overhead connection which descends just
lore leaving the pumping station building on its way to the fdters,

fOnrfhw

. Friction H§act for Mai, fhl9

\

~-^

— ' — ^ ' F^nds of 6vcfti>n Pip9 **'' ^ ^

Fig. 324.— Pump control at Ijcbanon*

Ithe excess thrown by the pumps flowing back througli the overflow con-
jocction. This puts no extra work on the punjps, however, except to
I overcome the friction of pas^sing the sewage through the pumps and
i pijws, as the entire system of pipes is closed against the entrance of

air, and the 0xc<i8si quantity descending to the lower level balances.

in work, an equal quantity raised through the same height by the
[pumps. In this descending portion of the main there is a hydrauho

valve and at the top of the vertical main t hc^ro is an overflow pijie which
iruiLM back to a cormection with the j^uction main of ilie pump. The

hydraulic valve \a oi>ened and oluw3d by pressure water mUuittod to

one end or the other of the actuating cylinder, by means of a foiu'^way

^iM

710

AMERICAN SEWBRAOE PRACTICE

cock. The water BUpply is taken from the ciiy mains. The four-way
cock is operated by a float in a chamber whit-h is connected with the
Imhoff tank by means of a 1-in. pipe, so that the level in this chamber Is
always the same as that in the tank. If the rate of sewage flow from tfa«

Fig. 325. — Pump chamber with automatic inlet.

city increases, the level of tlie sewage in the Imhoff tank will rise slig

and the hydraulic valve will then be opened to a oonreEpondirni^ ei

permitting a larger disdmrge of sewage to go to

If the rate of flow from the city is smaller^ the t*

sewage to fall in the Imhoff ttauk, thu& allowing tlie ttotit fto drop *

SEWAGE rUMPJUa STATIONS

711

»nd lurn the four-wiiy cock so v^ to dose the hydraulic valve
proportionately thus sending a smaller quantity of sewage to the
sprinkling filters.

In this syst<:tn of control the overflow pipe must connect with the
I suction pipe below the level of the sewage in the Imhoff tank in order
to have all the pipe-ends trapped.

Ridgewood, N. Y, — In must sewage pumping stations of small si^e
L reliance is placed upon the automatic starting and stopping devices to
[prevent sewage rising above a predetermined level, and in case of any
j accident to the machinery, an overflow pipe allows the excess sewage
I to escape. In a temporary plant at Ridgewood, Borough of Queens,
In. Y,, an overflow pipe could not be provided and consequently an auto-
matic shut-off valve wa*s installed. The plant is shown in Fig, 325,
from Eng, Record^ July 24, 1909. There is no screen in the plant, be-
cftuse the sewage is screened through No, 12 galvanized iron 1/4-ia*
mesh screens at the head of the pipe supplying the pumping station. This
inlet pipe has a 10-in. automatic float valve operated through a sysdem
of levers by a large ball float in the wet well. Ortlinarily this float ia
jnot reached by the surface of the sewage, for the automatic starting
[apparatus throws the pump into service before the sewage reaches the
'elevation of the ball float. There are two pumping units, each con-
I Fisting of a (>-in. centrifugal pump driven by a 15-h.p. induction motor
I working on a (>0-cycle 220-volt circuit, the starting and stopping being
controlled by \Vej?tingbouse apparatus.
Salt Lftke City.^The use of gearing between a small pump and it«

I engine or motor is by no means obligatory and some pump manufac-
turers have expressed a preference for belts under certain conditions,
although the tendency of the belts to slip keeps down the speed of the
pumps and belted pumps have a somwhat lower mechanical efTiejcncy
than direct-driven pumps on that account and also because of the side
pull on the bearings, A plant of this type is shown in Fig. 326. It
was built in 1907 at Salt Lake City, from the plana of Lewis C Kelsey,
and operates against a static head of 34 ft. and a total head of 65 ft.
The 40-in, sewer terminates in a drop manhole which has a vdved open-
ing into each part of a 30 ft. square pump pit, divided by transverse and
[longitudinal cross walla into four fairly equid compartments, two of
Ithctn serving as wet wells and two as dry wells. This arrangement
Ipermits the use of horizontal pumps, which are generally considered
j jiomewlmt easier to operate. The driving shaft to which the pumps are
|behcd has a 150-h.p., (iO^cycle, 3-plmse, 440-volt induction motor at
eud and a 1.50-h.p. 3-cylinder suction ga« engine at the other,
connected to the shaft tlirough a friclion coupling. The gas
luri*r Lm rated at 2fKJ h,p, and was designed to use anthracite, but
• fitrljr sueceasful experiments were made with a mixture of coke

42

AMERICAN SEWERAQE PRACTICE

and anthracite. The plant has the xisual purifier, scrubber, tar eic
tractor, and blower auxiliaries. The producer gas engine is generally
run during the period of peak load on the electric company*^ lines, wliiiii^
au extra price in charged for current.

I

I

\\\4\.l — .«^^^«

• ill *--..-' 1 * I 1 Ji

Vertical Section A -A.
Fig. 326. — Belted pimjp drive, SfUt Luke city.

Kansas City, Mo. — ^In Kansas City, Mo., there is an area of 5Q0i
along the Kanaaa River, from which it is protected by a levee, oceU|

by iniportaut busim^ss and manufacturing conipjiiiiiis. ^ '
industrial wastes from them, the drt^-weather flow from t
30 to 50 cu. ft. per aecrond. The trunk sewer i» 10 ft. i^
its outlet is so locate*! *^rti t)u' w<>un.r,> .^iv K*^ A

SEWAGE PUMPING STATIONS

713

ing most of the year. For about a total of one month, however,
the river stage is such that pumping is necessary, for which purpose
a gate-hoiifio has been constructed on the sewer, and a pumping station
liad been built upon a by-pass around the gate^ the portion of the sewer
below the gate forming the outlet conduit from the pump» Owing to
the intermittent ser\4ce, efficiency was not considered important in the
dc&tgn of lite plant. Each of the two contrifugal pumps is of the con-
stant speed vertical motor-driven type, with a rating of 30,0CH) gal. per
minut*^ against a head of 22 ft. In a description of the station in Eng,
Record J Feb. 22, 1913, 0, L. Eltinge, who was coimected with the design
and construction of this plant under City Engineer L. R, Ash, states
that pumps of the vertical shaft typo were selected, so that the motors
could be direct-connected and still be above the flood level, thus pre-
venting damage to them in case of flooded pump pits. As the plant

Table 172. — Ixfohmation Regarding Steam Pumping Btations

City

' 8

Lo««th, f I ,

jridth. ft

Urictbi to rtdctt. ft,

VIrktrrinI , .,,.,,
BoUtm. N .
Type

Tulttl bp..
Type

TaUil h,p
Pufnpi*. N"
Typa

Totui m if tl .
Ruction lift, ft
StAlir hond. It
1*otAl h<<A<i,

fnrticm, fi
(\M ijf tun.i

n..,I.L,...

18S

167

59

85

Brick

Wut<if

tulte

705

3

VerticiiJ

tnpl«»

evpiij].

1200

PluQcer

62 5

I 5 to S

72

1121,022
401,175
661,473

230

35

24^15

Brick

Scotch
tic tubu.

4

CorliJMi
triple

g50

4

O0'i42*

Cent

235

0

19

fSS.OOJM
180,000

I

e

3

1

i^

j( A

•1

i 1

f^ 1

l2

I
§

it

56

22
3S)
Brii'k

a

Wat<?r
lube
450
5
Vcrticut
h-«.
Pomp.
400
3,2
20'; 12'
Cent.
14
13 5
6
20.0

>64J20
8 OS'

300

60

22

3^

Briok

2

Wat4?r

tube

600

• 2

CariiMi

horu.

comp.

1084

t»: 2

24'; 42'

C«nL

26

.12.;)

120.000

136.520 \

121.500 /

12,401

136

126
Mi

Briok
2
Tubu-
lar
160
21
WortU-
ingiaa

l»

Cent,
2.25

e

8

126

HO
15
26
Briok
3
Tubu-
lar

mt

2

dupIcK

2«

Cent.
4

14
0

190.000
0 3

1126,000

3O.(K)0

63

30
16
27
Brick
2
Tubu-
lar
100
2
High
»I*ceci

70

2

8^

Cent.

3

m

S10.40(]

iiiu(iin {>iimp« wa^ rn m rived atiout IMl^ and thi* moror-drivi*n rotitrit'

ML! lulilit wa» put in iliipUo«>, ■ Tbeamall pump in drivcii by a 150 b p.

ii II i <.lu' dry^weather mswako. • Tbe two motored ri vt^u «?«!Utrifutfal« wnf«

[iut,,i.. (he cxiTA amount ni •ewage, wbeQ ilwro Ui a Urge ietnp^trftry populationt

\m rofort, • Without fouDdaiicmA,

m

d^

714

AMERICAN SEWERAGE PRACTICE

IIS

•J 'awjs^

a

08

lao Knooiox

::S8Seo9|eo|

I ^: o 22 a

0 CO

qoiiv *s!Am98

•VI

^o e^ 01 00 '^ ^

n

go

.01

is *

' -^ « ^: ^-

; CO CO o o ^ O
, ^ ^ ^ ^ ^ ^

) «0 a> Ob ea O

I ^ .1^ ^ V« j

8-^

fl 8 ^ w

8^

0 CO o 8 CO

'■ti

.2oeno»o».H^8'H »

o O o» '^

•c 5 '^ *^

S « Q

5

I

M

«

CO

s

01

CO

CO

0
<

1

CO

i

8

s

r*
«

0

-

^

1:^

CO

M

01

CO

eo

0
<

s

CO

S a
W 8

s

s

« :

0

I CO t- rrr^^do cs, s a « '^ '^

CeoNPOco'^jcc'^M 5c^2»^

I

• ft

: 1^ 00

6 -.--.,
8 a •« jd '

n^H

SEWAGE PUMPING STATIONS

715

^atanda idle most of the time, it was also cooHidered advisable to have
^Bhe motors as far from damp places as possible. The pumps wero
^Blaced low enough to allow them to be self-primed when the valves on
^^heir suctions are opened. Each pump is in a separate pit, to enable
repairs to be made on either of them without interfering with the
^—Operation of the other. As the drj^-weather sewage is so small that one
^■pump can handle it in a brief time, it was necessary to provide check
^Kralves on the outlets to prevent a reversal of flow when pumping was
^Kitopped.

The method of pumping in such ernes is as follows: After the gate is
closed, the sewage is allowed lo pond up behind the gate until the water
nirface nearly reaches the crown of the sewex, which takes about half
in hour. Then one pump is run for about ten minutes, when the
onding of the sewage is repeated again. When the pump is started
he first draft nearly empties the sewer near the intake, and it takes
nearly a minute for the nearly stationar>^ water at a distance from the
ition to get into full motion toward the pump. Another feature of
be plant, which has been shown by exT>orienre to be unsatisfactory
I the absence of gratings over the pump intakes, for hea\^y timbers have
dtared them; it was proposed in 1014 to install such gratings to remedy
im condition.

Some information regarding pimdpihg stations of a great variety of
types is given in Tables 172 and 173. The statements were furnished by
ttterested cit>' officials in every cq&q but one, and are doubtless as com-
parable as such information ever is. The statistics were furnished by
ibout a third of the engineers to whom inquiries were sent, and the
kiuthors are particularly grateful to them for supplying records that have
heretofore been unavailable for the use of most people.

ECONOMIC SIZES OF FORCE MAINS

A problem of frequent occurrence in the de-sign of sewerage works

the determination of the economic sizes of force mains. Given two

force mains of diiTerent diameters for conveying equal quantitic-s of

uwagc, the one of greater diameter will cost more* but the head due

&tion in it and consequently the cost of puntping, will be Icivs than

the pipe of smaller diameter The most economical diameter

^ pipe is one that will result in a minimum total cost. It is inipotisible

Jo determine the exact minimum cost for a term of years, on account of

[ideterminate losses from frictioUp variations in costs of coal, pipa and

libor, and uncertain changes in the quantity' of sewage to bo pumpctK

Making, however, the most reasonable assumptions as to cost of pip#

ftying and pumping losnt^n from friction, and increase in population! a

I for comparing thtj relative ecofiomy of several pipe lines of different

71G

AMERICAN SEWERAGE PRACTICE

diameters ma^^ be obtiiinod by finding the total annual cost necessary
in each case to operate and maintain the structure. This annual cost
conBists of the follovvinfj; amounts:

1. The annual cost of pumping and repairs, being approximately
an average of the annual amounts required during the life of the
structure, taking into account the increase in population, friction
losses, etc.

2. The annual interest charges on the cost of the property involved

3. The annual depreciation idlowance required. If the pipe line k
assumed to have some value at the end of the period under consider*
ation^ the depreciation factor is modilied so that the depreciation fund
amounts at the end of the period to the difference between the first
coist and the assumed reinaimng value of the structure.

While it is possible to deduce a mathematical formula incorporating
many of these variable factors, the resulting equation is too compli-
cated to be of much practical value. Furthermore it b necessAr>* to
make so many assumptions, in thcmselvea uncertain, that 8uc4i a
formula is of doubtful value when obtained. The most practical way
to solve such a problem is by approximation^ making two or three tts»-
sumptions as to the ecoDomiG velocit)' and working the resulta out in
detail according to the nbove cited principles. As an aid to judgment
in making these assumptions it is possilik to work out a comparativoly
simple approximate formula as follows:

Let X = diameter of pi|>e in inches.

Y = cost of pipe and laying per foot.

a — cost of cast iron in cents per poimd.

F = velocity in feet per second.

Q — quantity flowing in cubic feet per second.

An examination of the costs of laying cast*iron pipe in diCTeront pUoei
and under various conditions, indicates that this cost may be represcntctl
roughly by the formula

y = 20 + 2.a aX^ (I)

Ha2en and Williams' formula for the velocity of flow in pip4)s, is:

y = c^<»'".s O.N 0.001 -*>*>* (2)

When c = 100 in the Hazen formula, which is tlie value rccommi^DdiHi
for use under ordinary conditions for pipe which have been
sonie time, by redticUon Uie following formula may be oli
being the diamet^T in feet to correspond with H^ the hydraulic ra4iu.s
which is in feet in equation 2:

V « 56 /)'•** N"'**

l^j

SEWAGE PUMPING STATIONS

717

't(&mio^.( *oa5Jad'^*noi Butcioy jo joa^ JocI 5jd|ioq u\ iso^

O tn O LO O in
\a^ ^ ro K» ^4

O in

04 -

— (M CU ^ *

718 AMERICAN SEWERAGE PRACTICE

If the diameter is given in inches, (3) becomes:

V = ll.SXo-M^So-" (4)

also

Q = X X» F -5- (4 X 144) ^ (5)

Combining and reducing (4) and (5) there results

5 = 167Qi-"-h X*-»^ (6)

In this final formula S represents the loss of head in feet per foot d
pipe.

Let b = cost of pumping 1 cu. ft. per second 1 ft. high per year.
E = fractional part of day during which pumps are operated.
R = rate of interest plus depreciation or sinking fund charges
to retire investment cost at end of stated period.

Then the annual cost of pumping per foot of pipe is represented by
E b Q S, or substituting the value of S from (6)

167 Eb Q«-« -^ X*-" (7)

and the total annual cost of pipe line and pumping per linear foot of
pipe, is represented by the formula,

(167 E b Q«-85 ^ X^-")+ 20 R + 2.3 aRX'^ (S

Differentiating this equation with respect to X and pUicing the
result eciual to zero, for the purpose of determining the minimum value
of X, gives the following result:

X = 2.396 r^j Q«-^* (9)

If it be assumed that the cost of cast iron is 1.5 cents per pound, that
the pumps are operated 24 hours per day, and that interest and sink-
ing fund charges amount to 7 per cent,, the following formula results:

Q = 0.064 A'2.22 ^ 60-36 (10)

Tliis formula has been used in the construction of Fig. 327, from which
it is possil)lo to determine the approximate economical size of force
mains. If assumi)tions are made, other than those used in preparing the
diagram, with rep;ard to the fraction of a day during which pumps are
operated and the cost of ciist iron, the diagram may still be used, with
certain corrections. It will be seen that the diameter varies inversely
as a^'^^j n l)eiii^ the cost of cast iron, so that if the cost is 1.25 cents
per pound, the diameter obtained from the diagram should be multi-
plied l)y 1.03, and if the price of cast iron is 1 cent per pound, the di-
ameter should be multiplied by 1.07. Similarly the diameter varies

SEWAGE PUMPING STATIONS 719

directly hb K***'*, so that if instead of operating 24 houra a day the
piimps arc only operated 10 hours, the diameter aa determined from the
diagram should be multiplied by 0.87. Correction can be similarly
made for other values of R, The diagram is baaed on an assunied
c(K»f!tcient of 100 in the Haaen and Williams formula. If it Ib de-
sired to base the computation on a factor of 130 or for practically new
pipe, the diameter m found in the dia^am should be reduced 7 per cent.
This formula and diagram do iiot apply to materials other than cast-
iron pipe, but approximations may be made, as for instance where
wood stave or steel pipe is uaed^ by determining such a value of a, or
cost of cast iron, as would give the correct cost of some one size of the
main when built of the material under consi<leration-

The formula and diagram are based on the assumption that any
small change in the diameter of the pipe in order to arrive at the most
economical size would not involve any change in the pumping station
or pumpSt but would involve only differences in costs of pumping based
on average unit values. About the only factor of importance involved
is the eosi of fuel.

In long pipe lines, however, any change in diameter of pipe might
involve changes in all the cmnponents of the plant, size of station,
pumps, cost of operation, etc. Another method of Bnalysis of this
problem leading to practically the same results is given on page 6(Ki
of Turneaure and Russell's "Public Water Supply," second edition.

STORAGE BASINS ON TIDE WATER

Where the pumping plants are located on tide w^ater, it is occasionaUy
necessary to provide tanks or reservoirs into w^hieh the sewage can be
delivered wlule the tidal currents would carry it to places where it
would cause a nuisance. The first noteworthy example of such storage
In the United Statea waa the reserv^oir built on Moon Island in 1883,
as part of the Boston main drainage works. This had four basins hold-
ing 25,000,000 gab, and wa^ designed to store during a period of about
lO hours the sewage pumped to the Island by the Old Harbor Point
tion, the discharge beginning about an hour after tide commenced
to ebb. As usual at that date, the walls of the basins were built of rubble
n»a.*»onr>% laid in a 1:2 natural cemcnit mortar, and after some years of
service tlie mortar was found to be very soft. The floors were 9 in.^ of
concrete, the lower 5 in. being made with natural cement and the top
4 in,, with Portland cement.

The Bewago of the Hampton Institute \a discharged into a small fcidal
strtsam during the beginning of the ebb tide, and to store it during the
remainder of the day tanks were needed. The bost site for these wsm
on very low wet ground and the tanks were built above ground, as shown

720

AMERICAN SEWERAGE PRACTICE

in Fig. 328 (^n^. Record, Nov. 18, 1905). Each is 26-l/2ft. in diameter,
inside, and 13 ft. 4 in. high to the springing line of the dome roof, which
has a rise of 4-1/2 ft. The tanks are 46-1/2 ft. apart on centers and
between them is a ventilating shaft 50 ft. high, with which they are
connected, above their flow hne, by ducts. Two steam coils in tiie
bottom of the stack, supplied from a neighboring power house, increase
the draft.
The entire construction is of 1:2: 4, concrete, reinforced where neces-

FiG. 328. — Storage tanks at Hampton Institute.

sary. The walls of the tanks are 12 in. thick, and were plastered on the
outside and then given three coats of white water paint. The thru5t
of the dome is taken by a circular iron ring. Sewage is pumped into
each tank through two 5-in. pipes, which rise vertically against the wall
to a height of nearly 13 ft. above the bottom, thus keeping a uniform
head on the pumps. The sewage is drawn off through two 10-in. dis-
charge pipes, emi)tying into the creek at different places, and the two
tanks, which hold about 100,000 gal., can be discharged in 1-1/2 hourt.

^^ INDEX ^^^

721 ^B

^^^

Indeix to Tabi*bb

No.

0 1 1

2

3

4

5 1 6

7

8

9

0

9

30

156

i5fl

64

64

65

67

77

10

80

83

90

93

95

98

100

107

108

111

20

tu

112

U2

115

110

tl7

119

120

122

128

3U

129

131

134

137

142

143

153

154

155

156

40

158

160

103

155

160

160 107

168

109

109

50

170

17«

180

183

184

ISO 189

190

196

196

60

lt»S

199

200

200

201

302

203

204

205

230

70 '

232

233

237

244

246

346

240

249

252

252 '

80

2o4

257

362

268

268

273

273

274

270

278

SK)

279

291

310

318

319

319

320

320

321

322

100

322

323

333

323

334

334

320

333

334

335

no

336

337

338

330

340

342

343

344

345

348

120

356

357

360

363 1 304

307

378

384

397

405

130

414

415

417

418

410

420

422

434

425

429

140

440

448

402

462

403

404

464

474

470

481

1,%

4!i3

484

488

492

494

495

497

498

500

601

ItH)

507

591

592

593

505

595

622

067

668

670

170

070

671

713

>

Index to Illustrations

K«.

Q 1

1 1

2

3 1 i 1 5 1 6

7

8

9

0

27

33

30

42

50 1 60

60

60

60

10

5«

67

73

73

74 1

74

76

75

84

86

30

87

8S

89

92

i 94

i 94

i 94

1 94

1 94

1 94

30

1 94

% 94

100

100

103

i U>4

* 104

104

135

125

40

120

126

135

139

140

140

141

141

140

147

50

151

154

157

102

102

104

171

172

173

174

m

175

177

178

188

191

193

193

194

195

197

70

208

208

209 '

210

210

211

311

312

213

213

80

214

215

315

216

217

221

221

222

222

223

W

223

224

224

225

220

227

228

228

229

229

100

230

238

239

240

245

247

248

i250

273

274

no

277

t 288

290

200

302

303

304

305

306

308

120

309

310

347

355

358

358

300

364

360

360

130

375

379

383

392

393

393

394

394

395

395

140

396

396

398

398

399

399

*400

409

413

414

150

410

417

419 '

426

427

428

430 1

432

433

435

150

430

438

440

441

443

445

446

447

441?

4.M)

170

452

453

454

454

456

450

457

457

459

450

180

463

460

408

473

475

480

488

489

496

497

100

499

503

504

505

506

500

608

518

519

620

aoo

623

524

525

626

527

628

529

530

531

534

210

535

536

537

637

A38

639

610

540

511

543

220

543

544

546

647

548

649

649

661

552

553

230

553

554

555

657

668

558

669

660

661

502

240

663

563

566

608

669

670

i572

674

»574

676

2M

1570

577

579

580

682

683

»584

686

687

589

2rXl

502

593

594

697

608

699

600

603

0O3

004

27U

004

004

006

609

609

610

012

012

613

014

2SU

015

610

017

618

618

619

6S0

621

023

024

300

020

027

630

631

633

033

634

036

637

038

300

030

1 058

064

606

680

682

••684

686

687

088

310

600

691

693

696

t606

690

6Q7

698

1 698

099

AJO

7(K)

703

706

708

709

710

712

317

720

TU« number of tli« i»bl

0 uT lllitf^tration ia in be fuand by Ukinx Lho uoil titnf^ in

Omj hnrt

«f»nUJ fine itl the tap of i

uch tAbltj uud the ten* and bu»dj-i?d» ftgures in ike Icfl-

bmnd eaU ■

uihd. Id thv BT>ana corn

eaponding td the ltit4?rB<>ntion of the vortlriht K,tid horiio

nUl litin« ■

will b«* found th© |hme<? on

whiob tb« ubJc ar illuAlrniioQ *pp«iira. For exuinplc.

TAhte 47 ■

U 00 pibc« lOli, Tlia l«l
40

tcr i iiidaej^iei a toUia^ p1aU> Ucinc thfl pa4|e bwuiac Htmi

i aunibor. fl

INDEX

Acceleration due to gravity, 64

Adams, A. L.; wood-stave pipe design, 377

Adams, Col. Julius W.; biographical note, 14

run-off formula, 235

troubles in designing Brooklyn sewers,
19
Adams sewage lift, 678
Additive method of estimating run-off, 292
Adeney, W. E.; deposits in salt water, 112
Air, leakage in centrifugal pumps, 694

movement in sewers, 644

sewer, 551, 641

valves, automatic, 365
Alabama River, floods, 262
Albany, N. Y.; density of population, 160
Allegheny River, floods, 262
Allentown, Pa.; density of population, 160
Alliance, Ohio; leakage into sewers, 186
Alignment, unchanged between manholes or

lampholes on small sewers, 40
Alien, Charles A. ; Worcester sewage treat-
ment works, 29
Allen. Frank; equivalent sewer sections, 404
Altoona, Pa.; density of population, 160

leakage into sewers, 186

sewer sections, 433
Alvord, John W.; opinion regarding Kutter's

n,97
Analysis of stresses in arches, 471
Anchorages for steel pipe, 366
Anderson, A. C; pressure in trenches, 331
Andover, Mass.; water consumption, 176

volume of sewage, 189
Andrewes, Dr. F. W. ; sewer air, 642
Androscoggin River, flood, 260, 262
Aqueducts, Catokill, 373, 441

cleaning, effect on discharge, 91

Cochituatc, gagings, 91

Croton. hydraulic elements, 397
value of Chesy c, 90

gaging. 149

Hartford. 436

Jersey City, 435

lining. 373

Newark, 435

Bait Lake City. 450

Stony Brook, value of Chesy c, 90

Sudbury, gagings, 91
value of Che«y c, 90

Wachusett, cross-section, 436

723

Aqueducts, Wachusett, discharge, 89

hydraulic elements, 126, 395, 397
Weston, mortar lining of steel pipe, 373
Arches, masonry, 408
analysis, 471

voussoir method, 472
elastic theory, Turneaure's method,
478
French's method, 488
design of five-centered, 418
empirical formulas, 408
materials, 455
stone block manonry, 455
Area, drainage district — and run-off, 266,
313
increase of — in cities, 157
Arkansas River, floods, 262
Aroostook River, greatest flood, 260
Ash, L. R.; pumping station, 713
Asphalt pipe coatings, 368
Aaserson, H. R.; sewer sections, 431,. 453
Atmosphere, pressure of, 63
Attleboro, Mass.; water consumption, 176
Aubrey, A. J.; manufacture of vitrified clay

pipe, 346
Automobile trucks, weight, 464

B

Babb, C. C. ; gaging of ditch, 85
Backfilling, effect of early settling on
pressures, 336, 388

pressure due to, 331

weight, 467
Bacot, R. C. ; Jersey City sewer outlet

closed, 17
Bailey- Denton, J.; early used intermittent

filtration. 29
Bale, M. Powis; sewage pumps, 660
Baltimore, cesspools in 1879. 15

consumption of water. 168

density of population, 160

flight sewers. 549

growth in population, 151, 154

intensity of rainfall. 223

pumping stations, 36, 705

sewerage plan, 35

sewer sections, 436

sise of intercepters. 184

use of McMath's run-off formula, 249,
293

wood-stave outfall sewer, 380

724

INDEX

Bands for wood-stave pipe, 377
Bangor, Me.; flood flow, 260
Barbour, F. A.; economical pumping plants,
654
effect of sheeting left in trench, 335
pressures in sewer trenches, 329
pumping stations, 694
steady bearings for pumps, 674
thickness of vitrified pipe, 340
Barrows, H. K.; determination of stream

flow in winter, 101
Basements flooded by backwater, 6. 20, 296
Batovia, N. Y.; pumping station, 707
Bateman, J. F.; leaping weirs, 619
Bates, Jamra P.; drop manhole patent, 541
Bayonne, N. J.; density of population, 160
Basalgette, J. W.; appointed chief engineer
Metropolitan Commission of
Sewers and Metropolitan Board
of Works, 5
capacity of London sewers, 7
explanation of foul condition of

Thames, 6
minimum velocity in sewers, 7
transporting power of water. 111
Basin, 11.; distribution of velocities in
pipes, 86
formulas for flow of water, 77
weir formula, 136
Beach, Ldeut.-Col. L. U.; use of pipe without

bells, 357
Bear River, floods, 262
Bearings, pump, 674

Basket-handle sewer sections, advantages
and disadvantages. 3S6
examples, 435

hydraulic element^*, 394, 397
Bcriin, intensity of rainfall, 230
radial system of sewers, 34
Bends, allowance for in 8t. Louis. 117
early discussion by Roe, 565
eroesion of invert»<t on, 460
in small sewers, 40, 09
losses of head due to. 69, 512
Bernoulli, Daniel: theorem of flowinji water.

66, (W
B«'verly, Mass.; water consumption. 17<)
Birmingham. Ala.; decision regarding .Hew-

a^e disposal, .'U
Birmingham, England: hourly variation in
flow of sewage, INS
sewer gagin^s. 31ti
B*tum;u«*tic \n\n' coatin»c. 372
Blaok Warrior River. flo<xi. 2»".2
Blarkwell, transporting power of w:it<r. Ill
Board of Water Supply. Niw \(>rk;
hiturna.*tir pijH' coating. 372
Cat^kill :iqueilui-t. 373. Ul
BvHlit's. !;»»> of fulling. t>»'.
bond m brickwork. 455

Boston, deposits in sewers, 116

gagings of North Metropolitan sewers,

82
grades bad in early sewer, 17
intercepting sewers, authorised in
1876, 15
regulators on, 597
sise, 184
locking manhole cover, 550
manhole cover, 562
maximum flow gage, 311
method of designing storm-water

sewers, 287, 293
mortar lining of Weston aqueduct, 373
oil seal for Venturi meter, 147
population, density, 160, 161

growth, 151, 154
pumping stations, 694, 697
rainfall, flood record of Stony Brook,
257, 261
heavy storms, 232
intensity of rainfall, 221, 222
probability of rainfalls of different
intensities, 229
screens, 650

sewer sections, horse-ehoe, 383, 404.
436, 441, 443
multiple. 450
steps for manholes, 553
storage basins for sewage, 719
tide gates, 637

use of McMath's formula. 249
Brackenbury, R. A.; intensity of rainfall.

227
Brackett, Dexter; cast-iron pipe specifica-
tions, 343
pumping records at CUnton, 675
Bradbury, E. G.; leakage into sewers, 183
Bradley, W. H.; separate sewerage system.

23
Brahms; effect of friction in conduits. 76
Branches; spacing in Philadelphia, 42
Branch sewer, cause of congestion. 51
Breakage of pipe sewers; Manhattan
experience, 61
due to tamping, 334
Breed. J.B. F.; plain concrete sewer sections,
413
sewer gagings, 319

sewer sections. 4.39, 442, 446, 448. 4.'>3
test of automatic rain-gages. 212
utility of catch-basins, 521
Brolau. Germany; rainfall observations,
209
true siphon on sewer, 581
Brewer. Bertram; pumping station. 692
Briok sewor>*, cro-ion, 58. 457. 460. 461
life in Manhattan, 60
se. tioHH. 42f», 427. 428. 430. 432. 433.
43.>. 436, 438. 441, 443, 449, 452

INDEX

725

Brickwork, bellmouth junciiona, 567

character for tunnel liningg. 93

claraee for sewer work, 455

comparison with concrete, 401

deterioration in Manhattan sewers, 60

for manholes, 533

lining concrete sewers to prevent ero-
sion, 113, 461
Bridgeport, Conn.; density of population,'
161

flood record, 258
Briggs, J. A.; sewer sections, 451
Brockton, Mass.; classification of water
consumption, 167

leakage into sewers, 186

proportion of water supply reaching
sewers, 166

volume of sewage, 189

water consumption, 176
Bronx, Borough of the; cradles for pipe
sewers, 358

depth of chimney tops below street, 39

growth in population, 1^9

Kutter's n, 115

outlet of sewer, 632

plain concrete sewers, 414

quantity of storm water, 294

sewer sections, 414, 440, 443. 452, 453

street inlets, 518, 531
Brooke, W. T.; true siphon on Norfolk

sewer, 580
Brookline, Mass.; water consumption, 176
Brooklyn, Borough. of; flushing sewer. 47

growth in population, 151, 154

information for designing sewers in
1857, 19

Kutter's n, 116

large early sewer, 16

large manhole castings, 558

outlet and increaser, 633

quantity of storm-water, 294

sewer sections. 427, 430, 443, 447, 452.
453

steps for manholes, 553

tide-locked sewer outlets, 23

well-holes, 545
Brooks, John W.; infiltration of ground

water into sewers, 183
Brown, Wm. J.; sections of sewers. 421, 439
Brussels, sewer section with cunette, 449
Budd, John W.; sewer sections. 428, 448
Buel, A. W.; thickness of arches, 411
Buffalo, N. Y.; density of population. KM)
Builders Iron Foundry water-level recorder,

304
Bunslau. Germany; sewage farming, 27
Burdick, Charles B.; flat grades, 118
BQrkli-Zioglcr run-off formula. 235. 241,

29.'i. 295
Burlap protection of pipe coating, 372

Cairns, R. A.; sewer section, 437
Cambridge, Mass.; density of population,
160
design of storm-water sewers, 293
gaging of conduit, 85
sewer gagings. 318, 319, 320

sections, 438
water consumption, 168, 176
Cambridge, Ohio; raising sewage by ejector,

679
Camden, N. J.; density of population, 160
Canals, Basin's formulas for flow, 77

Chesy formula table, U. S. Reclamation

Service, 95 •

Chicago drainage canal, 30

gaging. 91
gaging irrigation, 85. 87. 88
Kutter's formula, 80
Canandaigua, N. Y.; water consumption

168
Canton, Ohio; leakage into sewers, 186
Cape Fear River flood, 262
Capillary tubes, flow through, 71
Carlisle, Pa.; sewer gagings. 98
Carpenter, George A.; improved rain-gage,
210
maximum flow gage, 311
sewage regulator, 606
sewer gagings at Pawtucket, 324
Carriage, water — and dry removal of fecal

matter, 12
Cars, weight, 462, 463

Carson. Howard A.; connection with Prov-
idence, sewers, 15
cross-sections of Metropolitan sewers,
385. 386, 429, 431, 434, 437
Castings, catch-basin covers. 529

manhole frames and covers. 555
Cast-iron pipe, 374

requirements for manhole and oatoh-

basin castings, 531
steps, 553
Catch-basins, Columbus, 524
covers, 529
Grand Rapids, 525
Manhattan. 525
Newark, 525
Providence, 523
utility, 520
Catenary sewer sections; advantages and
disadvantages, 385
hydraulic elements. 397
Catskill water works, New York; pipe
coatings, 373
section of masonry aqueduct. 441
Cellars flooded. 6, 20, 296
Cement pipe, absorption, 357
breaking load, 357

726

INDEX

Cement pipe, Colorado concrete, 353

manufacture 350

molded in place, 354

Wilson & Baillie pipe, 352
Centrifugal pumps, 662
Cesspools, Baltimore, 15

difference between English and Ameri-
can, 6

London-— in 1850, 3, 4

Paris, 12

removal of contents, 6, 15
Chad wick, Edwin; separate sewerage ssrs-

tem, 23
Chambers, drop, 630

gaging, 308, 550

i^creaser, 633

inlet and outlet — of siphons, 574

junction, 565

overflow, 607

silt, 623

transformer, 618
Channels, Basin's formulas for flow, 77

Kutter's formula, 80

Chesy formula table, U. S. Reclama-
tion Service, 95
Charleston, S. C; density of population, 160

Tide-flushed sewer without fall. 18
Chesbrough, E. S.; bad grades on Boston
sewer, 17

biographical sketch, 2

Hamburg sewers, 2

Parisian sewer sections, 11

private sewers, Boston, 17

tide-locked outlets, 23
Chesy formula for flow in conduits, 76, 77
Chicago, drainage canal, 30, 91

density of population, 160, 163

first American city having compre-
hensive sewerage, 14

flushing sewer, 47

gagings, dry-weather sewage, 189, 190
drainage canal, 91
sewers, 321
water conduits, brick-lined, 92

grades of sewers in 1881, 20

intensity of rainfall, 224

interceptcrs, siie, 184

pumping station, 089

sewer sections, 433, 434

use of Mc Math's formula, 249
Chimneys, on deep sewers, 39
Cholera; in England, 4, 10

in France, 10
Christian, S. L.; leakage into sewers, 183
Cincinnati, area increases, 158

gagings of sewers, lUo, 199

industrial sewage, 200

intercepU'rs, study of size, 203

riianhoIcH, 534
gaging, 309

Cincinnati, maximum sewer flow gaffe, 310

population, 154

rainfall curve, 294

water consumption and meters, 174
Cippoletti weir, 138

Circular sewer sections; advantaffes and
disadvantages, 382

Bronx, 140

hydraulic elements, 125. 290, 392, 397

Louisville. 148
Cities, changes in density of population, 161

German definition of different densitisi
of population, 274

growth of, 151

ratio of street surface to population,
274
Clapp, Otis P.; early Providence sewers, 15

equivalent sewer sections, 404

sise of storm-water sewers, 295

tide gates, 635
Clark, H. W.; deposits in sea water, 112
Clark, Rosooe N.; storm overflows. 616
Clarke, Eliot C. ; first Boston sewage pump,
655

prevention of floods in Stony Brook,
261
Cleaning aqueducts, effect on discharge, 91
Cleaning catch-basins, 523
Cleaning sewers, Croydon, 25

flushing, 588

Memphis, 25 \

Paris, 12 \

small pipes, 39 ^

Cleaning streets, by flushing, 522

Paris, 12 ^

Cleveland, classification of water usei'W

density of population, KK)

effect of meters on wat4jr consump.**
174

intercepting sewers, 33

leaping weir, 619

rainfall curve, 294

sewage regulator, 607

water intake gaging, 93

wellholes, 545
Clinton, Mass.; leakage into sewers. 186

pumping Mrith steam and electricity,
676

sewage reservoir, 049

volume of sewage. 189
Clock movements for rain-gages, 217
Coating pipe, Angus Smith's description of
his metliod, 308

asphaltic materials, 308, 309

Bitumastic, 372

burlap protection, 372

coal-tar preparations. 308. 372

concrete and mortar linings, 373

experience of Spring Valley VVat4»r Co.,
309

]

^ INDEX ^ 727 ^^H

^^m CnntinK ptp«i. Loa AneitJes ii^ui^lunt, 37 1

ConcTcito, aewora, rciaforoement alwaya do- ^^^^^H

^^m Cochituttrj; nquinluot, KneiriKB, 81

^^^H

^H CoeffieieiJtfi, Bftzin's formula, 77

eectious ^irbout rrinforcf>m«^tii, 58, ^^^^^H

^^H Chf-ty fonnuta, U^

413, 411. 410, 120, 433, 435, 430. ^^^^M

^^m diaeritiutJon of riuuiail, 209

^^^^1

^^1 H.txrii & Willinmif* furtnulii, 107

unUncd— uRCNd for high V(*lo«it]f«.11^ ^^^^H

^^m imperviouBtocM, 207

StreaarsB in arch crrws-iicetion, 503 ^^^^^|

^H Kuit«r'ft formula, 60, 94

tbickneait. itiiumiuiUi 407 ^^^^^|

^H «nfic«e, 128

working ^ircsRes. 51 1 ^^^^^^M

^H rc'UrJaUon. 270

Conncctidut Rivor; floodfi in. 202 ^^^^^^|

^H retcDtioa, 260

Ccmotjction^ of reciprocating putnpa, 060 ^^^^^H

^H rur>-o(T factor, 272

renirifugal pumps, 672 ^^^^^H

^H weire, 134

Cunnc<'tion« to hou»e».- tec House draiutt ^^^^^B

^H Coffin, Fr««man C; B^KinS ol Cambridee

Consumption of water, 167 ^^^^^|

^B . eniiduit. 55

Coatinuity, t^ijuation of — ^in pipe diiehargr'. ^^^^^|

p icwer 0cetionii. 423

^^^H

1 CoHin'tora; aee Iiit«rr«ptere

Contractdd vnin, 128 ^^^^H

^^ Colornfio Rivf^r, florxlA, 2ti2

Contracted wBin, formuln. 136 ^^^^H

^H Columbu*, Ohio; density of population, 100

Controlletv for pumpn, 091, 002, 005. 701. ^^^H

^^H dtfpooits in i»ti«rceptcr, 115

^^^H

^H flond flow, 2r)». 20U

Cooley'a formula for flood flo\%, 254 ^^^^^M

^^P hourly variAtiooB in flow, ISS

CorpuA Chriarti, Tex.; flat grades, 121 ^^^^H

^^M pumpinfc rtLiiLion, fl83

Corrugated pipe sewers, 374 ^^^^^^|

^H ^lunUard catrh-buiun, 524

Costs, appruiBal of Manhattan newer*, 69 ^^^^^|

^H Combined Mowemge «y9t«m,<9; advAOtaiet

exp«nditun<» for future tttmh, 32 ^^^^^^

^H ami dJt»advfintAK«?fl, 26

fluctuAUooA in crMtt of aimilar work, 27 ^^^^^|

^^E Compuruou of rplntiv© eco&ottiy of rliffcnsnl

influence on cro^-t^.-^ction, 401 ^^^^^^M

^H^ doaifcnn, 640

pumping Ktationa. 713, 714 ^^^^^|

^H Concord, M niM;.; in vprt«d niphaa, 57&

Covers, catch-basin, 529 ^^^^^H

^H leakikKtf inio s^wtsn, 186

leakase through manhole. 558 ^^^H

^^B roiuiholc bottom, 5^

locking device for, &50 ^^^^^t

^^m in wage reservoir. 040

manhole, d&i ^^^^^M

^^B volunif; of HCvriiKe^ 1^0

pumping ttation, fKlO ^^^^^|

Covington, Ky.; donfrity of populAtion* 100 ^^^^H

^M 5(\3

Cracfkii in sc$w«rti, 498, 509 ^^^^^|

^■CoQ0Tot4'. itdvantagc« for flewem. 16, 401,

Craxilfia, Bronx. 358 ^^^H

^H

Manhattan. 61 ^^^^H

^^B efl'ect of ct^cifolysU. 450

Medford, ^^^H

^^B io rtiiiifortMHi-poncr«t« pipe, 361

PhUudelphia. 358 ^^^^H

^^P liniRjK for Bt«?«l pipe, 37^

Waahington, 357 ^^^^^H

^V mwihkifi for fltiakiii« oo&erote in mold*.

Craig'e formula for floods, 255 ^^^^^H

H

Cramf?r'B formula for flooda. 255 ^^^^^^

^H mAtilioIe«. 838

Critif^al velocity, 70 ^^^^H

^H proportjona for BU Loui* iew^n, 421,

CroicPttcwDettnoyera' formula for tiuekneva ^^^^^M

^H

^^^^^H

^^M reinfori't^^ ftdvautv^es for «ewcm, 456

CrQton aqueduct, croea-a«ction, 383 ^^^^H

^H bridges. 583

hydraulic elements. 397 ^^^^^|

^^1 JurksoD pip<^, 302

value of Cbei!y 00 ^^^^H

^^H Loek-joint pipe, :i5d

Crot^n [liver; greatctit flood, 257, 259 ^^^^H

^^H longitudinal reinforcoment, 500

Croydon, England: ezpflrienco with iinaU ^^^|

^^H Parmlcy pipe, 303

acwcra, 25 ^^^^H

^H acwcr »cciionA. 413, 417. 420. 427,

Culvert formula, Burlington Ry., 254 ^^^^H

^m 433, 435. 43n. 410. 441. 443, 445.

Homer, ^^^H

^H 447. 450, 452. 453. 451

SanU Fe Ey , 254 ^^^^H

^^H fltr«MV«i ill reiuforct^fd section, 503

Ciinett« sewer sections. 391, 449 ^^^^^|

^^M UiickntmH. minimum. 407

Cunningham, Major Allen; values of ^^^^H

^^m traitflveriv^ mrift»ri'i'mc?nt, 500

^^^^H

^H Bfiwcr*, built in Wnnhington in 1SS5, 10

Curing cement pipe, 3.'}2 ^^^^^M

^H effect of wjurnittj on »hap« of invert.

Currents, float mpajtureinonts, 148 ^^^^^M

^■^ fiS

met43r mca^iurementa, 148 ^^^^H

728

INDEX

Cumntfl, traiuporting power. 111
Curves, allowance for — ^in St. Louis, 117

early discuBsion by Roe, 505

erosion of inverts on, 460

in small sewers, 40, 69

losses of head due to, 60, 512
Cushman, Dr. A. S.; pipe coating, 372
Cushman, James A. ; discharge of Waohusett
Aqueduct, 89

Davis, Joseph P.; biographical note, 15
Dayton, Ohio; density of population, 161

pumping stations, 691
Dead ends, definition, 40
Death due to sewer air, 551, 643
Definitions, bellmouth junctions, 567

branch sewers, 42

centrifugal pump, 662

cesspools, 6

chimneys, 39

clack valves, 659

closed and open impellers, 666

coefficient of imperviousness, 264
retardation, 270
retention, 269
run-off, 264

collectors, 45

contracted vein, 128

critical velocity, 70

cunette, 391

dead ends, 40

dry removal, 12

dry well, 648

entry head, 69

equivalent percentage of totally imper*
vious area, 275

flushing sewera. 47

force mains, 47

grade, 48

ground water, 181

house drain, 38

hydraulic gradient, 69

hydrodynamics, 62

hydrostutics. 62

itnpellera, 606

inlet time, 265

intercepting sewers. 45

invert<?d siphons, 46, 571

liit4^ral sewers, 40

open iiiipellers, 060

orifice, standard, 128

outfall sewers, 40

outlets, 40

piezometer tubes, 70

population densities in Germany, 274

pressure sowers, 46

propeller pumps, 003

regulators, 597

Definitions, relief outlets, 51, 597

relief sewers, 46

run-off coefficient, 264

screw pump, 662

separate sewers, 23

siphons, 571

standard orifice, 128

steady flow, 70

storm overflows, 597

time of concentration, 264, 266

trumpet arch, 567

trunk sewer, 44

turbine pump, 662

uniform flow, 70

vena contracta, 128

volute pump, 662

water carriage, 12

wellholes, 545

wet well. 648
Dejardin's formula for thickness of arches,

410
de Laval, C. G.; overloading motors. 665

piston speeds of pumps, 658

pump efficiency, 669

setting centrifugal pumps, 674

types of centrifugal pumps, 662
Delaware River, floods, 262
Delta sewer sections, see Parabolic sewer

sections
Denison, Tex.; water consumption, 168
Density of population, 159
Denver, Colo.; intensity of rainfall, 228

sewer bridge, 584

wood-stave pipe, 377
Denver l^nion Water Co.; angle wells, 550

wood-stave pipe, 377
Deposits; Columbus intercepter troubles,
115

effect on capacity of aqueducts, 91

minimum velocities to prevent, 114

more quickly formed in salt than fresh
water, 112

sewers at Boston to encourage, 116
Depth of sewers, conflicting requirements.
43

drop manholes, 43

influence of topography, 34

on hillsides, 40
Depuis' formula for thickness of arches, 411
Design of masonry sewers, 382
Des Moines, Iowa; manufacture of Jackson
pipe, 427

sewer sections, 427, 447
Detroit, Mich.; density of population, 100

Metropolitan district, 159

pumping station, 707

screens. 051

velocity curves in 30-in. pipe, 73, 86
Diaphragm in manholes, 562

gages for pressures, 305

INDEX

729

Dickens* flood formula, 255
Dieckmann, George P.; cement pipe mix-
tures, 350
Discharge of sewers, approximate German
method of computation, 54
comparative velocities in circular and

egg-shaped sewers, 384
diagrams of, 94. 400
examination of sewer design with refer-
ence to minimum flow conditions
121
gaging, 128
hydraulic elements of sections, 125,

290, 393
tables for determining, 56
Disinfection, fecal matter disinfected for

dry removal, 13
Disposal of sewage, effect on sewerage plan,
32
history, 27
, judicial decisions, 31
Distortion of sewer pipe in trench under

load. 356
Distribution of runfall, coefllcient of. 269
Ditches. Basin's formulas for flow in, 77
Chesy formula table, U. S. Reclama-
tion Service, 95
gaging irrigation ditches, 85, 87, 88
Kutter's formula for flow. 80
Dodd, C. H.; finishing top of manholes, 562
pumping station, 695
screens, 651
sewage regulators, 601
sewer section, 451
Donahey, Alexander; drop manhole patent,

541
Dorr, E. S.; adjustable manhole frame, 562
pumping station, 695
rainfall formula. 230
sewage regulators, 601
sewer sections, 437, 444, 451
Drainage districts, area affects run-off, 313

character affects run-off. 265, 269
Drains, carrying curb and gutter, 447
house, location and construction, 38
made compulsory in London in
1847, 4

payments for. 42
Paris, 12
storm-water, computation of quanti-
ties to be carried in Baltimore, Bos-
ton, Cambridge, Cincinnati, Cleve-
land, Louisville, Newark. New
York. New Orleans, Pawtucket,
Providence. St. Louis, Worcester,
293
gagingfl, Birmingham, Eng., 316
Cambridge. 318. 319, 320
ChiraKO, 321
Hartford. 322

Drains, gagings, Louisville, 319
Manhattan, 323
Milwaukee, 320
Newton, 322
Pawtucket, 324
Philadelphia, 324
Rochester, 326
Washington, 323
Wilmington, 323
judicial opinions regarding capacity,
206
Draper automatic rain-gages, 209
Dredge's formula for floods, 255
Drop chamber, 630
Drop manholes, criticism of use, 547
Medford, Mass., 542
Newark, N. J., 541
Newton, Mass., 543
patent claims, 541
Staten Island, 540
used on branch sewers, 43
Dry carriage of fecal matter, 12
Dubuat; resistance to flow of water, 72, 76
Dun, James; culvert formula; 254
Duryea, Edwin; wood-stave outfall sewers,

376
Duties of steam pumps, 657

Earl, George G.; flushing sewers, 596

minimum grades at New Orleans, 118

opinion regarding Kutter's n, 97
Earth, coefllicients of friction, 334

pressure on sewers, 331, 335, 388, 467

weight, 334
East Orange, N. J.; leakage into sewers, 186
Economy, analsrsis of relative — of alternate
projecto, 646, 654, 655

influence of — on sise of force mains, 715
Eddy, Harrison P.; Cincinnati sewerage, 158

depositing velocities, 116

sewer sections 431

specific gravity of sewage, 63

utility of catch-basins, 521
Edinburgh, sewage irrigation, 27
Egg-shaped sewer sections, advantages and
disadvantages, 382

hydraulic elements, 290, 393, 397

typical examples, 414, 430
Ejectors, Ellis, 678

Priestman, 679

priming pumps with, 673

Shone, 679
Elastic theory, for analysis of stresses in

sewer arches, 478, 488
Electrolysia in concrete, 456
Elisabeth, N. J.; Kutter's n, 115
Ellem, C. Howard; grades of Chicago
sewers, 20

730

INDEX

Elliptical aewer seotiomi, 389, 433

EUia ejectore, 678

El Paso, Texas; corrugated pipe sewer, 374

Eltinge, O. L.; pumping station, 713

Engines, pumping, 655, 705

remoieled from fly wheel to centrifugal,

706
types for driving centrifugal pumps,
676

Englewood, N. J.; experience with flat
grades, 119

Enlargements, loss of head due to, 69

Entry head, 69

Ericson, John; flow in brick-lined conduits,
92

Erosion of inverts; 68, 113, 431, 457

Essex Canal experiments on transporting
power of water, 109

Estep, J. M.; leaping weirs, 619
sewage regulator, 607

Evansville, Ind.; density of population, 160

Examples in approximate determination of
grades, diameters and relief out-
lets, 54
in use of rational method of computing
run-off, 263

Excavation, cost influences sewer cross-
section, 401
reduced by using pumps, 36

F

Fairhaven, Mass. ; rabing sewage by ejectors,

079
Falling bodies, laws of. 66
Fall River, Mass.; classification of water
consumption, 167, 168
effect of nieterH, 171
flood record, 258
water conHumption, 176
Fanning. J. T.; formula for flood flow, 254
Fardwell, H. F.; sewer nection. 444
Farnham. Irving T.; pumping Htntion, 084
Far Rockaway, N. Y.; sewnge pumping, 079
Fecal mutter, dry renioviil, 12
Fergusson automatic rain-gage, 207
Fisher, E. A.; Hcwage regulator, 006
Fitchburg, Ma«8.; induHtrial wa.ste8, 200

intercepting sewer, deteriiiiuation of
size. 184
FitaGerald automirtic rain-gago, 210
Fitiriiaurice, 8ir Maurice; Bawis of design

of London main drainage. 7
Five-centered Hewer sections, hydraulic
elements. .'i07
Hteps in design, 418
Flight MOwerH. 548

Flinn, Alfred D.; concrete pipe lining. 373
Flo:it gagoH, 301. 701
Float riieasuromenta, 147

Float well, 695

Floating matter, intercepting; 613. 632
Floods, basements and celbni, 6, 20, 296
frequency, 260

from large drainage areas, 249
tabulated records, 257
Flow of liquids, formulas for pipe flow, 72,
404
general principles, 65
in sewers, average rates (sewage), 206
character (intercepters), 205
computations, 54
gaging, 301
Fluctuations, volume of sewage, 189

water consumption, 175
Flumes, steel, 373
Flushing sewers, Charleston, 18
class of sewers, 47
general discussion, 123
Hamburg, 2
intakes. 585
manholes, 588
Rome, 2

with sewage, 588
Flush-tanks, Alvord & Burdick's practice,
120
automatic siphons, 592
Geo. W. Fuller's practice, 120
Hoboken, large-sise, 47
types, 589
value of, 123, 592
Folsom. Dr. C. F.; bad grades on Boston
sewer, 17
Hamburg sewers, 2

report of European sewage treatment,
29
Folwell, A. P.; losses of head, 69

utility of catch-basins, 522
Foot-vttlvea, 661, 674
Force mains, beat sise, 715
Ford, F. L.; sewer gagings at Hartford, 322
Forrest, C. N,; pipe coatings, 369
Fort, E. J.; sewer sections, 423, 431, 444,
448, 451
use of separate and combined systems in
Brooklyn, 37
Fort Wayne, Ind.; estimated growth of
suburbs. 158
size of proposed intercepter, 184
Foundations for sewers; influence on cross-
section, 400
influence on stresses, 497
piles, 365, 375. 426, 427, 430, 435, 436.

438. 440. 441^447, 440, 452. 4M
platforms. 427. 430, 436. 450, M4
Fox. Robert L. ; pumping station, 707
Frames; catch-basin, 529
manhole. 554
adjuHtubl(>, 501
water-tight. 503

INDEX 731 ^1

FTttininghAm. Mam.: leakAte into Bewem,

Ga^ng tewflt«, importaooe of itetuiil lima ^^^|

186

of eonn«*ntrMtJon, 207. 271 ^^^|

volume t4 M»wiice, ISO

mftCihotoB for, 309 , ^^H

wAt^r r'oiutimptton* 176

•torra water flow in. 301 ^^H

Fmnru, Jniiic» B.; pruvnintic»ii of AoemU In

Ongiagi of newora. dry wc«th«r. Btrmlog* ^^H

Htony Brook, 2G1

ham. 188 ^^H

wrif frmnu)^ 133

Chicago, igo ^^H

Froeniiui. John R; Ciimbridge sewwr

Cininnnaii. 196 ^^^|

l(iiffinff». »18

Coltimbui. 1SS ^^M

IfftCMponiniE poi»<»r of w liter. 100

GlovcT«villc 188 ^^M

▼«ltiM Iff Kutter't n« S»

Maaaaehuaetia towni, IM ^^M

Fnmrh, AHlitir W ; ttnalyMs oi «lMtie rinc

PhiUilelpbi** 190 ^H

48H

Toronto. 18S ^^H

Fresno. Cid,; minirnurii icrstdeti, 120

WorceMter, 188 ^^H

Friction, Brnhmii' tibflKtrvAtiona. 70

Gagiagii of sowers, Wf7t weather. BirmiQg- ^^H

Dnrcy'e obM?fvaiion*», 77

hani, Eng., 316 ^^H

increaiie «nth nice in Aewera, S3

Boaton. 82 ^^H

In piijeii, flO

Cambndgn. 318, 319. 320 ^^1

losNM flue to chftngo* in •!■« md

CUcago. 321 ^^1

direction, 09

Hartford. 322 ^^H

Prouy'i ohfwrvRtlon*. 76

LouiBvillt*. 319 ^^^^|

Fritfi Automatic rain-ctt«e. 3ti

MaohaiUn. 323 ^^M

Automntjc w«icr-«tAge resitfi^-r, 302

Miiwaokee, 320 ^H

Frontinus, wttlcr-wnite prvventiuii in

Newton, 322 ^^M

RorriB, 2

Fawtu^lcH. 324 ^^H

Fry*. AJbort t.; ihicktieM ftf ftroh«. 411

PMIadrlphia. 2124 ^^1

Fteley. Alphonits prowurei *jo mtuooty

Roch«tit<>r, 336 ^^H

mswmrt, :fSS

Washington. 323 ^^1

Budbury Aiiufnluet gagingii. 01

Wilmins^oa. 323 ^^1

weir formulft. 130

GanguiUvt** (ommta for flooda, 265 ^^^|

FuertfSR. JumiM H : rluMMii of eonsumption

Gardner. Mam,, leakage into eewers. 176 ^^^|

of WttU-r. 107

vol time of Bcwa«(.\ 189 ^^^|

effect uf lowcriftir urotiiid water. 43

water consunipiion, 176 ^^^|

AtMhrngibtiiko, ^m

Gaa, eewer. 041 ^^M

fluAhing •cwem at Uoboken. 47

Gatea. backwater and tide. 579 ^^H

! InlH lira*?. 266

loae in head due W. 60 ^^1

liiv«rtiHl siphon. 576

tides. 635, 006 ^^^H

pM-mholic t^wtfr sM^tion. 380, 440

Gate chamber, 651 ^^^|

pumpitiK eUtiofi control, 708

Geneeoo Rivrr^ flooda, 263 ^^^|

r«ct«ngulAr sewrr nerlionB, 446. 448

Gilli>spi€, R. H.; plain <M)ncret« nurflr aeo- ^^H

dH f«iiftmt>Pf. 625

^^^H

tld« KAtee. 640

GillcLie. H. P.; molOinv pipe in pla«#. 365 ^^M

Fulbr. CJfKjrite W : minimum Kn4^, ItO

r%*w» on Kuttrr** «, «7

GlovemvilU. N, Y,; di^riAloD rrcardinc ^^H

Fuller^ Wo«t«n E,« forniulA* for flood flowt,

■ewage dinijoaal. 31 ^^H

251. 200

hourly variation in Oow of arwagc, 188 ^^H

FuU«ir. Wm. B; ihtrkniiM of ornhM, 408

Gothic newer sr^'tiomi. advantage* and ^^H

diaadvantajiee. 3«5 ^^1

a

hydrmulir l•l^mouta, 393. 397 ^^M

QMm, Automuiii] rmln» JOT

Grades, at iunrtion*. 4.*^ ^^^|

8<Mit. Wl

Boaton. early defertn. 17 ^^^|

tiook. 307

Brooklyn, early uiinimuin. 20 ^^^H

piMunmtic ffrmmutm, 31 W

ehangf^ in umall M^wrra. 40 ^^^|

munmum flow. 310

Chicago, vt^ty Oat. 20 ^^H

1 B^tUng reio-gAgcfi. 31 K

eonipeunatioQ for our%'c«. 117 ^^^|

drop manhohia, 43 ^^^H

»tttfr, aoQ

irarly ^^^H

' ;^ibng flowing wuur, 127

101 ^H

Miwitf^ ai4

1

732

INDEX

Qmdwc boaae drunt. 39

kjdrmalie gradicBt, 23, 41

m^rimnm. 40

nummum. 48, 114

on fte«p killndea, 37

probierms solr^ by G«rni«a method. 54

r«lAtkm to «rr«v>n of imrcrtA, 1 13

relation to Tcl/^tjr, 106
GrAham. C. H.; aewcr wctioiu, 451
Grmod lUpids. Mich.: eatch-bttnn, 525
GruTel, lor eemeot pip«. 350
Grmritjr, aeoelerfttioa due to, 64
Grmy, Samuel M.; report oo Baltimore
•ewers, 16

•twPT aeetioiu. 428, 437, 448

utility of cateh-baMus, 521
Grease, eomp^ab on sewer walls, 40

in North Metropolitan sewers, 85
Greeley, Hamuel A.; Cambridce sewer
gacinsa. 318

sewer cagingi at Chieaco, 321
Gresory. Charles E.; inlet time, 265

intensity of rainfall, 227

run-off formula. 286. 243, 244

run-<jff IweUir, 272

sewer ca«ini(8, 323
Gregory, John II.; Columbos pompinc sta-
tion, 683

diacrams for discharce ci pipes and
sewers, 94, 400

Kutter's n. 97

IfrakaRe into newers, 183

nemi-elliptiral sewer section, 415
hydraulic (rlementn. 306. 403
Ground wnt^-r, effect of lowering, 43

Reneral rlij^rax^ion, ISl

tiuxhtftin of hamllinKf 4211

UMe<l industrially before entering newerH,
179
fIrunMky, C. K.; intennity of rainfull, 230

minim urn Krades, 120

San Krancirtco nt-wers, 21

HtoraK*' in wwern, 271
fnitteri*. 2

<-haMKe frr»m central to Hide in Pari*. 1 1

flow in, 20.>

forrninR part of t<hA of drain, 447

foiiN-d l»y wwage in PhiWidelphia, 18

iiil'tn for Htorm water, 51'), .530

II

HarkenHaek, \. J.; Kutter's n, \\'>
HuKue, Cliarl*'.'* A.; i>urfip capjwity. 0')2
H.ilf, U. A.; roi'fficifritt in (*h«zy urul

Kiitt'T for rim la.-, **,">
llariihiirK: fir'^t fity to have mo<N-rn ««'tt«T-

a^e sy«'f'Tn, 2
II:iriijirr>ti In-titut«', \'a.; puriipinK ntation,

r.s.'>
ntorajie tank, 719

Harrison. E. W^ Jersey CHjr aqaedtt, 437
HarrMoo. N. J.: flat padca. 121
Harrisbarc P^: dasMficatioa of wato- eon-
sompCioii. 167
density of popolasioa. 160
fluahinc intake. 586
inrcrted siphon, 576
parabolir tewer section, 380, 446
rectangular sewer section, 447
silt chamber. 624
Hartford. Conn.;
436
^assification of

167. 168
sewer gacingm 322
storm overflows, 615
Bastincs, Lewis. M.; gspnci of Cambridf

seweri. 319. 320
Hatton, T. Chalkley: value of Kutter's a.
98
flat grades, 120
sewer seetions. 428, 442
Haywood, W.; connection with London
main drainace. 5
criticism of Roe's table. 8
Havana, Cuba, molded pipe for narrow

trenches, 362
Hawluley run-off formula, 235. 238
Haxen, Allen; flow in capillary tubes, 71
Hasen and Williams' formula, 101
pipe coating. 368
pressure on pipes, 329
steel pipe. 366

tables for McMath's run-off formula,
240, 247
Hazlehur^t, Jame^ N.; breakage of pipe
Hewers, 3^
minimum Kradeif, 118
Head, definition. 68
entry. 00

in centrifuKHl pump tests. 669

loAiK*!*, enlargements and contractionji.

09, 512

curves. 512

frictir>n, 09

valvcK, 09

Venturi meters, 143
mea«»urement on weirs. 132
llederstedt, H. H.; change of crown of
Pari.nian street* from concave to
convex, 1 1
H<'n<-lrick, Calvin VV.; intomjity of rainfall,
230
wwer section, 437
wo<»d -stave outfall sewer. 3SO
Hermy, I). L.; wt>o<l-<tave pi()e. 377
II«riry. A .!.; heavy rainfall«, 26.H
H«TinK, Dr. Rudolph; biographical note,
10
clarification of sewerage systems, 32

INDEX

733

Hering, oomparison of dry remoyal and water
carriage, 13
cost of lateral and branch sewers, 43
design of Chicago drainage canal, 30
design of junctions, 44
inverted siphons, 576
report on Baltimore sewers, 16

on European sewerage systems, 26
run-off diagrams and formula, 235, 243
sewer gagings, 323

grades on steep hills, 37
utility of catch-basins, 521 '
Hermann, E. A.; erosion of sewer inverts,

113
Herschel, Clemens; floods in Stony Brook,
261
Venturi meter, 138
Hill, C. D.; intensity of rainfall at Chicago,

230
History of early sewers, 1
Hoboken, N. J.; density of population, 160
flushing sewers, 47
ground-water level in, 43
sewer section, 447
tide gates, 640
Hobrecht; planned Berlin radial sewerage

system, 34
Hoffman, Robert; rainfall curve for Cleve-
land. 204
Holmes, Glenn D.; leaping weir experiments, '
621
reinforced concrete pipe, 363
sewage regtilators, 601
sewer sections, 437. 442, 448
storm overflow, 612
Holyoke. Mass.; flood record, 257

hourly and doily changes in water

consumption, 175, 177
water consumption, 168
Hook gage. 307

Hopedale, Mass.; double manhole, 530
volume of sewage, 180
water consumption, 176
Horner, W. W.; allowance for resistance to
flow on curves, 117, 512
analyHia of sewer arches, 471
criticism of drop manholes, 547
culvert formula, 254
erroneous run-off measurements, 313
example of rational method of designing

storm-water drains, 275
five-centered arch sewer section, 418,

446
inlet time, 265, 314
locutiun of Htrcet inlets, 516
rainfall at St. Loui;*. 225
rertanRtilnr sower Heotions, 300
Horrorks, Dr. W, H.; wwcr air, 642
Hf>rsc-8ho«' M*wor scctionM, advantages and
disadvantages, 386

Horse-flhoe sewer Motions, ezamples, 436,
438,440
hydratilio elements, 305, 307, 404
Horton, Robert E. ; determination of stream
flow in winter, 101
effect of snow on floods, 256
floods in 1013, 261

"Weir Experiments, Coefficients and
Formulas," 138
Horton, Theodore; discharge of North

Metropolitan sewers, 82
Houses, drains, 2. 4, 12, 38, 42

water supply for different classu, 168
Howe, M. A.; tests of sewer pipe, 337
Howorth, Ben.; cast-iron outfall sewer, 375
Hoxie, Capt. R. L.; designed large concrete
sewer in 1883, 16
sewer gagings, 323
Hudson, C. W. ; analsrsis of elastic ring, 488
Hudson river, greatest flood, 260, 262
Hudson, Mass.; pumping station, 604
Huf eland, Otto.; appraisal of Manhattan

sewers, 50
Humblot; Parisian sewer sections, 11
Humphreys and Abbot; ratio of mean to

surface velocities, 108
Hydratilic elements of sewer sections,
basket-handle, 304, 307
circular, 125, 200, 302. 307
egg-shaped, 200, 303, 307
gothic, 303. 307
horse-shoe. 126, 305, 307
parabolic. 308
rectangular, 300
semi-circular, 300
semi-elliptical, 125, 307
Gregor>-'s, 306, 307
Louisville, 305, 397
special, 126, 306, 307
U-«haped. 308

use of diagram for circular sewers for
those with other sections, 403
Hydraulic gradient, 60

important in designing combined sew-
ers, 48
Hydraulirs, 62
Hydro-chronograph, 302

I
Ice, effect on floods, 256

effect on velocity curves in rivers, 75,

101
weight, 63
Illinois River, floods, 202
Ilstrup, Carl.; flushing manhole, 586
Imhoff, Dr. Karl; minimum velocities, 115
quantity of sewage and run-off in
German cities, 274
Industrial sewage, 200
Infiltration into sewers, 182

^ ^ ^Bp ^^^^-^ ^^^^^^^^^1

^^^H time, 265. 314

Swxy City, N. J.; KutterV n, 11/1 ^^M

^^^^^H InktA, street; nuthora' Al«ndurd, 51 Q

sewen ehoked by elo^g outlet. 17 ^^^

^^^^1 BroQs, 617. 531

steel sewer pipe, 3fi5 ■

^^^^^B location.

Joboson. F. P; rtiodulti* of rupture ^j^^B

^^^^H PlLUudclphia, 520, 53<1

vitriHed day, 341 ^^^|

^^^^^H Inflpucliun, MnnhiiltAD pip« sewore, 61

Johnson. J. Hr. sewer oeetions, 423 ^^H

^^^^^^B through Initipholt^, 064

Johnfltown. Pa,; denidty of population* 160' fl

^^^^^H Joterrepters. Halumore, 36, 1^

flo<id renofd. 258 I

^^^^^^^^B BatnlgLHl4?'» buia of design. 7

Joint Outlet 8ewcr, New Jamy, bridge*. 1

^^^^^^H

682. 583 1

^^^^^^^^H of flow in, 205

ga«inj0i of disebarge, 98 ^^J

^^^^^^^H

leakage. 186 ^^B

^^^^^^^^^H Cincinnati, 200

outlet. 027 ^H

^^^^^^^^H

Joints. Jaekson pipe. 362 ^^H

^^^^^^^^H roQtrol of entrance of sewage. 597

lo€k-joint pipe, 300 ^^H

^^^^^^^^^H detailed ostiniate of vohimea to be

reinforced concrete^ 509 ^^^B

^^^^^^H earned, 122. 200

eteel pipe. 366 ^^H

^^^^^^H Fitohbors, 184

tc«ts by Howe. 340 ^^B

^^^^^H Wayne. 1B4

without hclU, 358 ^^H

^^^^^^^^H eeneral features, 45, 184

Junctions, bell mouth. 566 ^^H

^^^^^H lAiuLiville, 184

CMtreful d«*mgri neod«Hl, 44, TfTO j^^^f

^^^^^^H Milwaukee, 184

eurve». Uoe*ti eommeuts un, 56A ^^H

^^^^^H New Bedford. 122, 184

dropping invert grade at junctiAas, 49

^^^^^H North Metropolitan. BoMton, 178, ISO.

flat-topped, 567

^^^^^^H 184

^^^^^H 12

K

^^^^^^^^H Pamuiic valtey, 184

^^^^^^^H

^^^^^^^H Pravidence. 184

Kitnsafl City. Mo.; puntping iKtwage. 712

^^^^^^^^H prox'ision for atorm water, 204

Kauliuun, Gustave; oement pipo inanu-

^^^^^^^r Byracuc^. 184

faclure, 353

^^^^^V Inverted egjc-skuped newe^ iteelionN. 432

KeLsey. L. C; pumping station, 711 ^^H

^^^^^B Inverted aiphoQfi, oomputatton of diiieh&rge,

fiewer scetion. 451 ^^H

^^^H

Kennebeo Rivtsr, greatest flood flow, 2m B

^^^^^1 dffifiDttion, 46, 571

262 I

^^^^^B examples at Lnui«AHUe. Woonsneket.

Kimball. J. U4 design of masonry sawvitt^fl

^^^^^B Concord, HarriehurjE. Chicagn.

^H

^^^^^B Baltimore and PhiUdelphia. 573

Kingiivilli-, Te:t,; flat gradoa, 121 ^^B

^^^^^^H Inverts, brick lining to oLeok erosion. 58

Kinnicutt, Prof. Lentiard P,; Wofi»sl^^^|

^^^^^^^ erosion.

sewage treatments 29 ^^H

^^^^^^^

Kirkpatriek, Walter G.; caaHmn manhdt B

^^^^^^^^^H At junetions.

frame, 561 1

^^^^^^^^B

KirkwocKi. James P.; biograpKi«'a] noi#, 14 1

^^^^^^^^H porous to admit water, 16

cheeked plans of early Brookty u sewets. 1

^^^^^^^ stresses, 487. 490, 497

^^B

^^^^^H Iowa Eagiaecrinc Experiment Station;

pipe ooatinga, 368 J^^H

^^^^^H investigation of ptMsure* in

^^^^^H trenches and strengtb of pip«, 331

aewernge design, 18 1

^^^^^H Iron. ca«t; pipe, 374

Kopa. J. do Bmyn; intvnstij of raialall «i 1

Saf annab. 230 |

^^^^^B step*, 563

KuiebUng. Emil; formiiiM for §mod At,^ M

^^^^^B trrlgatioo with aewaiee, 27

250, 254 ^^B

^^^^^^ Ithaoa, N. Y.; wood stave pipe. 370

intenMty ol rainfall. 2.^ ^^B

rainlalli^i r. 23(1 ^^B

^^^^H

rtinKiir (u ^^^B

«i»W«.r li«e«L«r. 2M ^^^^|

^^^^^^^H^&ekson. L. DA.; vittucw of Kutter*i n, hO

^^H

^^^^^V Jnney City. N. J.: aqucdurt wm

' ^^1

^^^^^K^^ ilensity of paptiiaii<m, 100

1

^^^H^^^^^^^K ^^^^V ^^

^r V^^^V

Lippincotl, J. B.; vnluea of Kutt**r'i n. S7 H

Livy, Homan hou#e eonntfCtit^riA, 2 H

Uu<U*w, Waller.; isruwtii in Munhntluu

Lloyd- Da\nei!, D. E.; RUKtiiica At Oirmitut- ^M

popuUiioit* 16JI

haul, Ens.. 31(} ^^H

liAjnphoIoa; ^fomt>hi• cippricoee uiuatis*

Londa oil Ac^wcrs, dr>ad lo(«d«. i<S5 |^^^|

fttctory. 25

geD(>rid ffUitoment, 50 ^^^|

um; »tul dttticccrotut fcMturvo of, Uft4

live lojwb, 401 ^B

LftHPjwiU*r, P»,; wwor «»<tiir»nfl. ^27. 4aS, 449

Mamton and AndorsoD'd invMitie«- H

hmac, Mot*'»; bad ^mdc^, 17

lintu, 3.12 ■

lnogrb|i)iii*iiI no lis H

proportioD of loada reaching sewers, 465 ^^B

Hnmburit Bcwera, 2

«uperfieiiiJ loAdfi on backfiUiiig, 330 ^^^|

Luieml wwors, 40

unvym metrical, 511 ^^^|

lAtliiiin« Biddwiu; caiiniAiiMD of future

Lucid Governincnt Boiird, infTu«no« on sew* ^^^^H

X>f»pul»ition. 152

agf* trDatment in EnjEJAtid, 29 |^^^|

tyrvknr>.4a of nrcht**, 411

reinforct^d'concrelc ««>wage wurlu givoa ^^^1

LAttincJi; upe in Homes 2

nSH of 15 ye»r«. Ifl ■

Lairobi«, C U*; report oii BtUUtnore Miwera,

"Suggeatioiu M to Plaos for Main Sew- H

Id

emge, DraitiagA and Wfttor Sup- ■

IjiutorburiE's foruiuU for flocxk, 3r>0

ply/" 24 ■

L«irrenc« Exp^irimcht Station, 2y

0tortn-wat«r rpquirvmonis. 34 ■

Lftwrvoce. Maw,; dn>tmfirnlioQ of Wftt«*f

Loek-bar pipe. 367. 027 ■

eonsutnptJioti. 1U7

Lock-joint pip<>. .3.^1. 3Mf ^^H

dt^ttsity of popultition, IrtO

Locking rover for miudiolcw, 5SI9 ^^^M

ifffocl vt mctcra ua wiK»r conaumption,

Locomoiivi>?. weight. 482 ^^^B

171

Loudon, fludt^r* opidcmicfl, -1 ^M

witter oonjuttiptim), 17*J

curly j)QWer», 5 ^^B

Lftwe; enpttdty of mwith, judloinl opinion.

ercMiioo of tcwer inveru. 459 ^^H

2^6

growth. U2 ^^1

diapoAul uf <««*wi«itc, judicitd npinioti, 3t

hi«t«fry of early drniuHKe, 3

corly Ktiielish twwernii*. a. 4, o, 10. 38

Loa AngHw. CaL. tttiU^ filmmbor. 551

flfjMMJod wwr'r»; judiciid t>ptijion, 21, 21)6

wewvr bridge. 5A4

Bcw^igf^ forbiddt-n to bv diaohnrinvd into

Btwl pip« eoating, 371

London »<•<*»»« tiefort) 1S15, ii

Louim-iiJft. Ky.: deosjiy ol pfipuUtion, ItK)

L»WB. J, Purry: sower wr, ft4l

hydraulic ••lem«ot« of ■emi-elllptical

wK'tion. 39.5

into »©wt-r», 182, 402

impro%'emenl of Br>argrM» eraek, fliQi

of air in writ.rifuir»l pumps, m*

indtiinrial wastes. 200

inteuBity of rainbill. 2^

L(*ikpitiK weirs, 019

inverted ntphorw. 673

Lebanoa, Ph.; pimipiM« »utif>n. 7i»*i

manh«l(? w-ith Wttt4?r-ti«ht dmphrujtt.i,

LeC4iot«. J N ; t4?»!ii of ptimpiitg pUnta,

6Ha

WiO

outlet <ttructurei, 02$ ^_

tipic«ti<^r, M««,, vol u run af KWttiis 180

pliiiu t'oocretc nowifrt, 413 ^^^|

L«ia«iftter. Cniflaud; vurroum of air in

iiuiintity of Btorm watar. 294 ^^^^H

•ewcre, M4

Ncwt^rgAgingH. 31S ^^H

Utu, E, A.; d<<po«iu in ma w»t«r, 112

,M»wer leetions, 4l«. 440, 441, 440» 447. ^^M

Uwwton, Me,, fl««Ml flow it] Aodruacoggin.

^^M

2tiO

fl|i«. of int(ore«pl^r«, \M ^^H

' ' ' t' fiiAnhol*?, OGO

Low., Emll*.; Uupknoa* of ninwory arohns* ^^H

formuln. DU

^^M

' 'iM.f, t,j lUmbunt jhhI

LoweU. Ma*-. : *l«"«**y ^' pc*pulat.on, 101 ^H

rt muMtvm, 2

wai*r ronsumpuon. I7ii ^^H

^■^*°*"'' "'**' «nd mortar in

l.oy<^joy. K, A : combinallrm manboli^. MO ^H
hydr»«Ue elemMit* .if Boaton l»«ta«boe ■

^^^rcn>^

artrUoM. 404 ^^J

^^^HP"^* V* -^ *>'" I'uiriitmidinobiirtiiuf

taiional moibod ol d«igning -torro^ ^^

^^^^V^ MUlburt, 401

tut^n D 14; Vhtrkne-of arebns, 411 ^^M

wal^r coDOunipti'^'v >*'' ^^H

^^H^ 736 pSI^^r ^1

^^^^^y M

Marlborough, Mass,; leakage into wwen, 1

ISO ^

^^^^^^H McCluiv, F. A., newer »cctioD, 455

volume of sewage^ 180 ^^H

^^^^^H MoComb, D. E.; built large concrete Hewers

wat«r consumption, 170 ^^^

^^^^1 16

MarstoP, Aoson; investigation of pressures 1

^^^^H McrMAth, Robert E.; run-off forrouU. 235,

in trench en, 331, 405 1

^^^^H 245. 201

Marvin automatic rain-gage, 215 I

^^^^H McNulty. R. J.; lockinc devioe for miuilinle

M ft whey, K. G.; nir currenta in sowen* 0#4 J

^^^^^H

Mnxiinum flow gage, 310 ^^fl

^^^^1 M»ekiQtoHh, WiUiAm; fluah-Uink. 590

Measurement of flowing water, 127 ^^H

^^^^^^B Madi»OD, Wis.; olntMificntioo of walnr

Modttdd, Mass.. leakage into •ewer^ im ^H

^^^^^H eoQAumpLion,

Mfdford, Maiw.; cradle for pipe sewers, 35S-^^B

^^^^^^B loakAgc into acwcrti. 186

drop manhole, 542 ^^B

^^^^^H Maginnb pitcel flume. 37;i

MemphJ4i, Tenn.; oxperienee with small j

^^^^^H Maias, wnior; ose Pipe», w&ter.

eewers. 24 ^t

^^^^H Manhntteo, Borough of; npprokal of

manhole bottom, 536 ^^H

^^^^^^P Mwert, 50

pumps, 065 ^^H

^^^^V Canal St. Hewer. 10

Mercantile sewage. lOS

^^^^H caieh-b&ain, 526

Merckf 1, Curt.; anliquAriao of eogineerioff. t

^^^^^B cliuH«i of wat«r oonflumption, 100

Meriwether, Coleman; Lock-joint p^pe, 350

^^^^^1 heavy ralnfalla, 233. 234

Merrinmc river: floods. 85, 263

^^^^^^^ Kutt«r'8 n. 115

Mery weather, H. F.; sewer bridge, 684

^^^^^^^^^B manhole caiitmg«t. 555

Metcati, Leonard; east-iron sew«r pipe, »3l

^^^^^^1 populatiou. 151, 153, 154« 159

cooBtauta in Chesy and Kut»*r fofn»- ^^

^^^^^^H daily ch»iig«ii« USH,

ulae. 65 ^H

^^^^^^^H refful&tion rojEnrdinc houao driiina, 99

wftter cooaumption, 170 ^^|

^^^^^^^H Mwer gagings. 323

Metcalf & Kddy. analyaia of streswa in M

^^^^^^^^B aewer plan influcaoed by e««y di«po«al,

masonry arches, 488 1

^^^^^H

diagram for discharge of oirvulatr vwsn^^^H

^^^^^^^P storm-water, c^timat^A. 205

^H

^^^^^^^ lide-lo<>ked outteut, 2'S

double manhole, 530 ^^^|

^^^^^m Manholes, bottoms, 535

flood flow formula, 251 ^^H

^^^^^^^^ oompenMlion for curve« in, 40

Kutter^M n. 04 ^^H

^^^^^^^H diapfar&Rmi in, 503

minimum grndea, 114 ^^H

^^^^^^H 530, 540

rainfall eurvp«, 230 ^^H

^^^^^^H drop.

reinforced-conerete dealgn. Oil ^^H

^^^^^^1 Mtdford. Man., 543

^^^^^H J.« 641

street inlet, 510 ^^H

^^^^^^H Maaa.. 543

Meters, Simplex, 142 ^^M

^^^^^^^^B patent clftinu. 541

Ventun. 138 ^^B

^^^^^H Staten lalaod. 540

water consumption affected by, 170 1

^^^^^H flushinif. 5gg

Methuen, Mass ; wat4$r eonMumptiun, 170 ^^M

^^^^^^^H 'frames and eovofB. 554

Metropolitan Board of Works, 5 ^^H

^^^^^H 308, 550

MetropolitHD ComiiUssiou of ^were, 4, S ^^H

^^^^^^B

^^^^^^^H civiag acooas to utid«rdnuni, S8B

New York, ernaion of ■ewera, 111 1

^^^^^^H location. 533

population, estimaiea of growtji, 1^ 1

^^^^^^^H Lovejuy. 540

cKaniteB in chamcter daring Si I

^^^^^^^^^B omitted in early Memphis sewern, 25

hours, log ^^m

^^^^^^^^H

run-o(T, 23 ^^H

^^^^^^^^^B side entrance, 533, 535

tid<»-l0aked snwer ouilefa, 22 ^^1

^^^^^^H

utility of eateh-baetiia, 521, 522 V

^^^^^^^g

veloeitiea neeeaHftfy to move aaUA^ ■

^^^^^^^^ Manometer, for Venturi meter. 111

112,116 ■

^^^^^B Mao8cr«h, James; Worcester sewage tmat-

Mntropolitnn H<'werag« Hf^^m <Botlflt^{ ■

^^^^^^V ment. 29

etoss^ - MTUvvv^ SHW 4A^hJ

^^^^^■^ Mftpn, rt*ticf map used by Wort he u. dT

H^H

^^^^^^^^^ Mttrkmartn. r 1 forrnutn

^^^^^^H

tt»2 ^H

^^^^^^^B

1

INDEX

737

MctropolitaD sewerage sysVcMn (Boston)
leakage into sewers, 183, 186
oil seal on Venturi meters, 147
proportion of water supply reaching

sewers. 166, 178
ratio of sewage to water consumption.

180
screens, 651
size of intercepters. 184
Metropolitan Water Works (Boston), con-
crete lining Weston aqueduct, 373
discharge of Wachusett aqueduct. 89
Miller. Hiram A.; sewer section 437, 442

storm overflow, 613
Mills, Frank H. ; inverted siphon. 576
Mills, Hiram F.; transporting power of

water, 109
Milwaukee: fluctuations in volume of
sewage. 190
flushing sewer, 47
industrial wastes, 200
leaping weir, 618
population, density, 160

growth, 154
sewer gagings. 320
sise of intercepters. 184
water consumption, classification, 167
estimated per capita increase, 175
proportion reaching sewers, 166
Minneapolis, effect of meters on water con-
sumption, 172
flushing intake, 585
wellholes, 545
Modesto, Cal.; minimum grades, 120
Mohawk River, application of McMath's
formula. 249
Kuichling's formula for flood flow, 250
Mohr's analysis of earth pressures. 468
Monongahela River, floods. 262
Morristown, N. J.; scwcr bridge. 583
Morse, H. S.; Cincinnati sewerage, 158

maximum flow gage, 311
Mortar lining for steel pipe, 373
Motors, electric; economy of use at Clinton,
675
overload capacity required in driving

centrifugal pumps, 665
selection for pumping servirc, 675
Murphy. E. C; formula for flood flow. 251,
261

N
n in Kutter's formula, 94
Nappe, forms when air is cut off from

beneath sheet, 135
Natick, Mass.; leakage into sewerH, 1H6

volume of sewage, 189
National Board of Health; 16. 24. 25. 32.

37,44
Neillsville, Wis. ; capacity of sewers discussed
by court, 22
47

Newark. N. J.; aqueduct section, 435
density of population. 160
drop manhole, 537
Kutter's n, 115
manhole, 537

quantity of storm water, 294
standard catch-basin, 525
variations in cost of pipe sewers. 27
New Bedford. Mass.; estimates of required
capacity of intercepter. 122
growth of population, 157
sewer sections. 440
size of intercepter, 184
water consumption, 176
Newbury port, Mass., water consumption,

176
Newell, F. H.; values of Kutter's n, 94
Newell, H. D.; gagings of concrete conduits,

93
New Haven. Conn.; density of population,

161
New Jersey State Board of Health; mini-
mum grades, 115
New London, Conn.; wood stave pipe,

379
New Orleans, La., drainage, 51, 672
flinhing sewers, 596
intensity of rainfall, 227
Kutter's n, 97

leakage into sewers, 183, 186
minimum grades, 118
screw pumps. 672
storm-water estimates. 295
Newton, Mass., drop manhole and undcr-
drain overflow, 643
experience with screens, 650
pumping station, 684
relative economy of pumping and

expensive sewer, 654
sewer gagings. 322
water consumption, 176
New York; mhs also Borough8 of Brooklyn,
the Bronx. Manhattan, Queen.^ and
Kiohmond.
bitumastic pipe coating, 372
concrete pipe coating, 373
density of population, 160
Nightsoil, cn.st of removal, 6, 15
Nipher, F. K.; intensity of rainfall. 220

ruin-guKc screen, 219
Noble. Thcrou A.; values of Kutter's n, 8»
Nordell, Carl H.; additive method of esti-
mating run-off, 2f)2
Norfolk, Va.; density of population, 160

true siphon on sewer, 580
North Attlelxiro, Mass., water consump-
tion, 176
North Brookfield, Mass., leakage into

M»wi«rs, 1K6
Noyes, AUxTt F.; drop manholes. 542

738

INDEX

O'Connell'fl formnU for floods, 255

Odora, from catcb-baaxu. 523

Odcen. H. N.. aatomatic flush-tanlu, 595

rux»"Off and population ratios. 273
r>fden, Utah, sewer section. 447
Ohio River, floods. 262
Omaha, flushing sewers. 596

judieial decision on Waring system. 21
Orifices, discharge through, 128
'Outfall sewers. 46

cast iron. Waterioo. 375
steel flume. Salt Lake City. 373
steel pipe. Rochester. 367
wood. Palo Alto, 376
New London. 379
Ithaca. 379
Baltimore. 380
Outlets, closed in Jersey City causing
nuisance. 17
definition. 46
design. 625 ^

Bronx. 632
Brooklyn. 633
Joint Trunk Sewer, 627
Louisville. 628
Minneapolis. 626
Rochester. 627
Washington. 38, 634
Winnipeg. 626
tide locking. 6. 23
Overflows, storm, 34
design, G07
Boston. 613
Ch,- vol and. G08
Hartfonl. *,\h
Kirhmorid. 618
Syracu!»«f. 012

PaiN. for rrrmoval of ffcal matter. 13

Pal'> AJto. Cal. ; w^kk! stav*.- outfall M-wcr,

Panta^raph. used in cors«i-»cctioninK sewers
to *i't«-rrnirj#' rhanKPf* in form, AiV)
Parabolir f»<.'wr-r s<-ctions, advantaKC-'-'i and
dir^ailvantaKv.-*, 389, 401
exariiplf?!i. •t40

hyrirmlir- fl.rrm-ntn. 397. 39S
Pari**, <arly m-w< rj*. 10

m.'ttlinK and rirre«?nini? jM-wa^f at

ColcrnJx."* pumping .station. 6.'>1
truo -jipFion on wwrr. .'>S0
ParkfT. A V. . h--a«t with rurb and KUtt«^r on

roof -lab. 44>>
I*.'i''nil«'y. Walt«'r C. comiMjnsation for
curvature. 'y\2

Parmley, retnfOTecd-eoBcrete pipe. 363
ruD-off formula, 244. 286
storm overflow, 607
thickneas of sewer archca, 412. 429
Passaic Valley Trunk Sewer, base qoaatities
lor fixing sise. 184
industrial wastes. 200
value of n used by Hering A Fuller and
John H. Gregory, 97
Passaic. N. J., density of p<^>ulatioa, 160
Passaic River, greatest flood flow. 259. 262
Patch. Walter W.; gagings of Sudbury and

Cochituate aqueducts. 91. 149
Paterson. N. J., density of population. 160
industrial wastes. 200
sise of interceptera. 184
Pawtucket, R. I., sewage regulator, 606
sewer gagings, 324
storm-water estimates. 295
water consumption. 168
Peabody, Mass., water consumption, 176
Penobscot River, greatest flood flow. 260
Peoria. 111., leakage into sewers. 186

water consumption, 168
Perronet's formula for thickneas of arrh.

412
Pettenkofer's theory of typhoid origin. 181
Philadelphia, consumption of water, 174
cradles for pipe sewers, 358
difficulties in early designing. 18
flight sewer, 549
gutters used for sewerage. 18
Bering's standard sections. 16
intennity of rainfall. 222
junctions, bellmouth, 566, 570

flat rwtfed. .569
location of separate sewers in street, 42
manholes. .>J7
castinic'}. 5.53
locked cover, 562
steps, 5.53
population, density. 160

growth. 151, 154
sewers, cross-sections, 426, 4.30. 438,
441. 450
ga«dnKs. 89, 196, 324
wood stave pipe, 3s0
street inlets. 519

covers, 530
WiAsahickon Creek, floods. 25S
inverted siphon, 579
Philbrick, Kdward S.; biographical note. l.>

tide-locked outlets, 23
Phillip*, A. E.; concrete crndlc fi>r pipe
sewers, V\'ashington, 357
outlet, ft3. 635
pumping station. 701
sewage regulators, 601
tide gates, 640
value of flush-tanks, 592

INDEX

739

Phillipa, John, claimed first luse of separate
sewers, 24
egs-shaped sewer, 382
lack of house drainage in London. 4
velocity in sewers, 8
Piesometer tubes, 70
Piles, cast-iron jet, 375
concrete, 632

rotted on sinking of water table, 41
supports for sewers, Boston, 436, 441,
4oO
Bronx, 452
Brookljm, 427
Hoboken, 447
Jersey City, 365
Louisville, 440. 447, 440. 454
MeUopolitan. 435. 438
Philadelphia, 426, 430. 441
Syracuse, 449
TompkinsviUe, 375
Wilmington, 427
Pipe, cast-iron. American Water-works
Association, 344
New England Water-works Associa-
tion's specifications. 341
resistance to internal pressure. 341
sewers at Tompkinsville and Waterloo.

374
variations in thickness. 330
Pipe, cement, absorption. 357
breaking load. 357
Cdorado concrete pipe. 353
manufacture. 350
molded in place. 354
Wilson A Baillie pipe. 352
Pipe coating, Anguw Smith's account of his
coating. 3((8
asphaltic coatings. 308. 369
bitumastic. 372
burlap protection. 372
coal tar. 308. 372
concrete and mortar linings, 373
experience of Spring Valley Water Co..
369
' Los Angeles aqueduct coating, 371
Pipe, corrugated. 374

Pipe, reinforced concrete, gagings of 16-, 30-
and 46-in., 03
Jackson. 362
Lock-joint 351. 359
Parmley. 363
Pipe, steel: Jersey City scwetfi. 365
Lock-bar. 367. 627
Springfield water pipe. 366
Pipe, vitrified, absorption. 356
breakage in trench. 334
breaking loads. 356
cracks. 349

curved pipe, <limensions. 348
joints, shape of bell, 319

Pipe, vitrified, joints, tests by Howe. 340
Washington ring type, 357
manufacture, 346
modulus of rupture, 341
pressures, internal, 328

external. 328
specifications. 349

strength. Burcharts & Stock tests. 339
Howe's tests, 338
theory. 337
thickness. 341. 347
Pipe, water, discharge of. 72. 86
flow through. 68, 108
formulas for velocity in. 77. 101
Paris sewers containing mains. 11
rMistance to flow. 72
steel. 366
Pipe, wood stave. 376
Piping, for pumps. 660. 672
Piston speed of pumps, 658
Pitot tube, 127

Pittsburgh, Pa.; density of population,
160
junction chamber, 567
sewer sections, 435
water consumption and meters. 174
Pittsfield. Mass.. volume of sewage. 1K9
Platforms for manholes. Brooklyn. 548
Memphis. 536
Seattle. 536
Platforms for sewers. Boston. 436. 450
Brooklyn. 427. 430
Cleveland. 544
Queens. 427
Plumb bob. used in gaging streams. 307
Plymouth. Mass.. water consumption,

168. 176
Pneumatic pressure gages, 306
Pollution of rivers, effect of street wash,
34. 51
Engli.sh reports on — in 1865 and 1875.

28
judicial opinions. 31
Population, rharacter affects volume of
sewage. 103
density, aiuumcd in London main
drainage. 7
change.s in, l(i8

German clai«»iification of different
denMitioH. 274
general diHcussion of probable rhangcK,

150
relation to run-off, 273
relation to street area. 274
PfMNonti's formula for floods. 255
I'ot.'«4lani, (lerniuny; true siphons on

wwerR. 5H1
Potter. Alexander: bridges for sewers. .'>83
gagingM of joint outfall sewer. 08
leakage through perforated covers. 558

740

INDEX

Potter, minimum grades, 120

sower outlet, 028
Precipitation, 207

frequency of heavy storms, 231
intensity of, 220
Pressure, assumptions in designing five-
centered arches, 418
atmospheric, 63

at junction of sewer and manhole, 534
developed by fresh backfilling, 388
intensity of water, 65
on sewer pipes, 328, 468
on water pipes, 329. 341
llankine's theory of earth, 467
Priestman ejectors, 679
Priming, centrifugal pumps, 672

reciprocating pumps, 662
Private sewers; protest against — in Boston,

17
Problems relating to grades, sixes and relief

outlets, 54
Prony; investigations of flow of water, 76
Providence, R. I.; character of early sewer
work, 15
density of population. 160
industrial wastes, 200
Metropolitan district, 159
proportion of water supply reaching

sewers, 166
sise of intcrcepters, 184
standard catch-basin, 523
storm water, estimation of, 295
tide gates. 635
Pullman. 111.; separate sewerage system, 24
Pumps, capacity and service requirements,
652
centrifugal, efficienry, 669
methods of driving, 675
performance. 604
piping and priming, 672
sotting. 072, 094
tab) OH of capacity and power. 607,

668
tests of plants, 009
theory. 003
types, 0(;2
reciprocating, piping, 600
piston 8i)eed. 058
types. ()')('}
Pumping spwago, Baltimore, 30, 705
Batavia. 707
Berlin. 35
Boston. m\, 097
Cambridge. 079
Chicago, 089
ColumbuM. 083
Cost, Boston, 077
Clinton. 070
of stations, 713, 714
Dayton. 091

Pumping sewage, Detroit, 707

economic aise of force main. 715

effect of storage on, 647

Fairhaven. 679

Far Rockaway. 679

Hampton Institute, 685

Hudson, 694

Kansas City, 712

Lebanon* 708

London, 45

machinery for, 655

Newton, 684

Providence, 705

Ridge wood, 711

Salt Lake City. 711

Saratoga, 694

Schenectady, 678

Waltham, 692

Washington, 701

Winona. 679

Worcester, 681

Queen automatic rain-gage, 213
Queens, Borough of; Kutter's n. 115

run-off estimates, 293

sewer sections, 427

sewage pumping, 679
Quincy, Mass.; proportion of water supply
reaching sewers, 166

Rainfall, absolute measurement, 219
coefficient of distribution, 269
form of curve, 227
for which sewers should be designed.

29()
general discussion. 207
heavy storms. 231

intensity, at different points rert'i\-ing
rain simultaneously, 269
curves, Baltimore, 223

Boston, 221, 222, 229

Chicago, 224

Denver. 228

Eastern United States, 22 1

Louisville. 224

New Orleans, 227

Philadelphia, 222

St. Louis, 225

San Francisco. 228

Savannah. 223

Spokane, 227
probability of storms of different

intensities, 229. 231
recommended method of determining

intensity, 231
time of heaviest precipitation durinjc

storms, 20H
travel of storms. 312

INDEX

741

Rain-gagea, automatic, 207

Draper, new and old patterns, 200
Fcrgusaon, 207
FitzGerald, 216
Frie«, 211
Ilellman. 217
Marvin, 215
Queen, 213
Richard, 213

setting and exposure of, 218
Randolph, Isham; sewer section, 434
Rankin. E. S. ; cost of Newark sewers, 27

erosion of inverts, 361
Rankine, W. J. M.; earth pressures, 467

thickness of arches, 410
Ransome, E. L.; molding cement pipe in

place, 355 »

Raritan River, floods, 262
Rates, effect of water — on conmimption, 173
Rational method cf estimating storm-water

run-off, 263
Rawlinson, Sir Robert; cesspools in Paris, 12
rule for sisc of sewers, 8
"Suggestions as to Plans tor Main
Sewerage. Drainage and Water
Supply," 24
Reading, Pa., density of population, 160

leakage into sewers, 186
Reciprocating pumps, 655
Recorder, Builders Iron Foundry water
level, 303
Sanborn flow, 306

Stevens' continuous water stage, 304
Venturi meter, 140

used in sewage-flow regulator, 600
Rectangular sewen* sections, advantages and
disadvantages, 300
examples. 445, 447
hydraulic elements, 307, 300
Register, Fries automatic water stage, 302

Venturi meter, 140
Regulator; in flushing chamber, Harrisburg;
687
Moisc, 502

sewage flow — for interceptcrs, 507
Boston. 507
CoflSn. 600
Heveland, 607
Pawtucket, 606
Rochester, 606
Syracuse, 601
Washington, 601
Reinforcement in concrete sewers always
desirable, 402
longitudinal, 500
transverse, 506
Relief outlet, see Storm overflow
definition, 51, 597
general discusnion, 51
Relief sewers, 40

Repairs; limit of conditions when they are

advisable in brick sewers, 60
Rcpport, Charles M.; sewer sections, 434
Reservoirs for sewage. 647, 703, 710
Residential sewage, 105
Retention, coeflicicnt of, 260
Reynolds, Irving H.; piston speeds, 658
power pumps, 656

triple expansion vertical pumping
engines, 658
Reynolds, Osborne; critical velocity, 70
Richard automatic rain-gage, 213
Richards, W. U.; wood-stave outfall sewers,

370
Richardson, Dr. Clifford; pipe coatings, 360
Richmond, Borough of; cast-iron sewer, 374
heavy rainfalls, 233
Kutter's n, 115
overflow chamber, 618
U-shaped sewer, 440
Richmond, Va.; density of population, 160

sewer sections, 433
Ridgewood, N. Y.; pumping station, 711
Rio Grande, floods, 262
Rivers, application of McMath's formula,
240
flood flows, 240

tables of flood flows, 257
flow formulas, 76
flushing sewers from, 585
gaging, 127
pollution, 28

judicial opinions, 31
storm water, 34, 51
transporting power of current, 100
velocities, curves, 74, 75, 87

ratio of mean to maximum surface,
108
Riveting, on steel pipe, 366
Road rollers, weight, 464
Robison, Prof. John, transporting power of

flowing water. 8
Rochester, N. Y.; density of population, 160
outlet, 627
rainfall records, 220
sewage regulators, 606
sewer gagings. 326
hU>c\ pipe outfall sowers, 367
Roe's table of size of combined sewers for
different areas, 8, 0. 238
Brooklyn u«o of, 20
Rogers, Ktlwin H., sewer gagings at Newton,

322
Rosewator, Andrew; flush-tank, 590

protent against Hniall si'wers. 21
Roughness, cfK^fTirients recommended for
Kutter's formula, 04
engineers' opinions, 05
Royal CoiiimiHsion on Sewage Disposal,
treatment of storm water, 34

742

INDEX

Rubble masonry cradles, 426, 438. 441

for sewers, 455
Run-off, storm water; additive method of
estimating, 292
analysis of relation between rainfall

and run-off, 312
Brooklyn, early estimates. 19
character of sewer district affects

gagings, 314
coefficient of run-off, 267, 272, 311
comparative results of McMath and

rational methods, 291
conditions affecting rate, 263
flood flows from large areas, 249
formulas for estimating, 235
gagings, Birmingham, 316
Cambridge. 318. 319, 320
Chicago. 321
Hartford, 322
Louisville, 319
Manhattan, 323
Milwaukee, 320
Newton. 322
Pawtucket. 324
Philadelphia. 324
Rochester. 326
Washington. 323
Wilmington. 323
German methods of estimating, 269
inlet time. 265. 314
London, estimate for main drainage, 7
measurements giving erroneous results,

313
Metropolitan Sewerage Commission's

views. 22
rational method of estimating. 263

oxamplc, 275
retention and retardation, 209
St. Louis curve, 277

time for water to reach sewors. 2rt.>, 314
time of concentration. 200, 313
Hust, CharleH H.: newer seetionH, 428
Ruttan, Col. N. H.; flush-tank. 592
outlet.s, 026

Winnipeg HeweraRo system. 538
Ryves' formula for flood flows, 255

S

St. Clair River; velocity curves in, h7

St. John River, greatest flood. 200

St. Joseph. Mo., reinforced-concrete pipe,

St. Louis, compensation for curvature, 117
den.sity of population. 100
erosif)n of inverts. 113
inten.-*ity of rainfall. 220. 225, 20S
investigation of inlet time. 314
manh<^le, 535
Mill creek sewer litigation. 22

St. Louis, population. 151. 154. 160
rectangular sewer sections, 390
run-off curve, 277
sewer bridge. 584
tumbling basin. 547
types of large sewers. 383. 418, 421.

443. 445
use of McMath's nin-off formula, 249
Sacramento. Cal.. minimum grades, 120
Safford. Arthur T. ; constants in Cbety and
Kutter formulas. 85
weir table. 134
Salem. Mass., priming centrifugal pumps.
673
water consumption, 176
Salt Lake City. aqueduH section, 450
pumping station, 711
steel flume, 373
Sand, coefficients of external and internal
friction, 334
flow of water through, 71
for cement pipe, 350
weight. 334
San Francisco, Cat., defective sewers, 2!
density of population, 160
intensity of rainfall. 228
pipe coating. 369
Santos. Brazil; parabolic sewer section, 389
Saratoga, pumping station, 674, 694
Savannah, Ga., density of population, 160

intensity of rainfall, 223. 268
Savannah River, floods. 262
Saville, C. M.; Hartford aqueduct section.

437
Schenectady. N. Y., density of population.
100
Ellis ejector plant. 678
Schodcr. Ernest W.; effect of variation in

assumed values of Kutter's n. 90
Schult*. C. F.: gaging Cleveland water

intake, 93
Sch ussier, Hermann; pipe coating at San

Francisco. 369
Schuyler, James D.: values of Kutter's n, SS
Scioto River, greatest flood, 260
Screens, O.'iO. 69{». 703
Seal for Venturi meter connections to

sewers, 147
Si'attle, Wash., manhole bottom, .536
Si'brinK. L. B.; raising sewage by ejei'tor!,

078
Semicircul.-ir sewer sections, advantages and
disadvantages. 391
examples. 443

hydraulic elements, 397, 399
Semi-elliptical sewers, advantages and
di.'^dvantages. 3H8
analy.sis of stresses in. 498
(liscliarne of Gregory's t>i)e, diagram.
■100

INDEX

743

Semi-elliptical sewors, hydraulic elementa,
Louisville type, 395. 397
special type, 396, 397
Gregory's type, 396, 397
types. 415, 416. 441
Separate system of sewerage, 23, 24
advantages and disadvantages, 26
Baltimore, system, 35
double manholes, 539
influence of disposal and topography, 33
location of drains and sewers, 42
use on Brooklyn water front, 37
Waring patents, 24
Sewage, action on metals, 650
composition, 62
first flush from streets. 204
industrial. 200
mercantile, 198
pumping, 646
residential, 195 «
specific gravity, 62, 63
treatment and disposal, 27

influence on sewerage plan, 32
volume, assumptions for interceptors,
205
Brooklyn early assumptions, 19
Chicago. 190

district characteristics influence, 192
gagings in Massachusetts cities, 187
ground-water leakage, 181
hourly variations. 188. 189
investigation at Cincinnati, 200
London, main drainage assumptions.

7
method of estimating, 150
North Metropolitan system. 178, 180
Philadelphia, 196
ratio of water supply to, 179
Hewer junctions, fixing elevations at — , 45

general features, 565
Sewerage: Biooklyn use of combined and
separate systems, 37
character of districts affects design, 192
classification of sewers, 38
conditions governing sewerage plan, 32
leakage into sewers. 182
period for which sewers arc designed, 121
respective fields of combined and sepa-
rate systems, 26
separate system, early uses, 23
valuation of Manhattan system, 59
volume of sewage, 150
volume of storm water, 263
water carriage and dry removal, 13
SowerH, brick, erosion, 58, 457, 460, 401
lift- in Manhattan, 60
MfctionM. 426, 427, 428, 430, 432, 433,
435, 430. 438. 441, 443. 449, 452
Sew<TH, capacity, bawic daily quantities for
intcrccpters, 184

Sewers, capacity, comparative velocities in

circular and eggnshaped sewers, 384
determination of capacities from tables

of capacity on 1 per cent, grade, 53
effect of capacity on interpretation of

gagings, 271
examination of capacity with reference

to minimum flow conditions, 121
Gregory's diagrams, 94, 400
Horner's diagram, 290
judicial opinions on necessary capacity,

296
Metcalf & Eddy's diagrams, 94
Sewers, classification, branch sowers, 42
flushing sewers, 47
force mains, 47
house drains, house sewers, or house

connections. 38
intercepting sewers or collectors, 45
inverted siphons. 46
lateral sewers. 40
outfall sewers, 46
relief sewers, 46
trunk sewers, 44
Sewers, cleaning, by flushing. 588
Memphis, 25
Paris, 12
small pipes, 39
Sewers, cost, fluctuations in cost of similar

work, 27
Manhattan sewerage system, 59
Sewers, cross-sections, analysis of stresses

in, 472
basket-handle. 386. 394, 435
catenary, 385. 394, 432
circular. 382. 392. 413. 414. 426, 427
cost of constructing different types, 401
cunette, 391, 449
delta. 389, 401, 446
double, 391, 450. 452
egg-shaped. 382, 393, 414, 430
elliptical, 389, 433
equivalent, 404, 444
five-oentered, 397, 445
general considerations governing seleo-

tion, 58
gothic, ,385, 393. 426, 428
Hering's paper on, 161
horse-shoe, 386, 394, 404, 436. 438. 440,

445
influence of construction methods and

available space, 400, 507
inverted egg-shaped, 432
par ibolic, 389, 401. 446
Paris. 11

rectangular. 390. 445, 447. 450
selection of dimensions, 407
selection of type, 391
Hemi<>irrular. 391, 443
scmi-elliptical, 388, 394. 402, 415, 441

744

INDEX

Sowers, crosa-section, stability, 402

thickness of masonry, 407

triple. 391. 453, 454

U-shaped, 389
Sewers, depth; conflicting requirements, 43

drop manholes, 43

inHuence of topography, 34

on hillsides, 40
Sewers, examinations of condition; Boston,
depositing velocities, 116

cracks in rcinforced-concrcte sewer, 498

London, 461

Louisville, 460

methods used in Manhattan, 61

Philadelphia. 89

Worcester, 457
Sewers, flight. 548
Sewers, gaging, dry weather, 188

methods, 127, 301

wet weather, 82, 318
Sewers, life, in Manhattan, 60
Sewers, location, in street, 41, 42

under curb and gutter, 447
Sewers, openings into, leakage through
badly made, 187

should discharge at angle to sewer
axis, 40
Sewers, pipe, see Pipe
Sewers, private, protest against in Boston,

17
Sewers, size, assumption that sewers rur
full. 41

Croydon and Memphis small sewers. 25

diagrams of sizes and velocitioH, 94, 400

effect of sudden change of, 512

example of determination of size, 54

house drains, .'19

judicial decisions regarding necessary.
21

lateral sewers, 40

Hawlinson's suggestions, 8

Roe's table, 9

selection of. 402
Sowers, storm- water; see Drains
Sewers, stresses in, 471
S<'wors, submerged, vol< (cities in, 123
iSewcrs. tide -trapped, 6, 23

velocities in. 12.*1
Shedd, J. Herbert; designer of Providence

sewers, 1.")
Shof^tiiig, effect wln-n left in trench on earth

pressun*. 'XV\
Sherman, C. W., fornmla for intensity of

rainfall, 2.'«)
Sherman, Iv C ; storm overflow, ()13
Sherman, L. K.; gaging.^ of Chicano drainage

canal, 91
Slierrerd, Morris H.; Newark aqueduct. 4:^7
Shoes for wood-stave pipe bauds, .378
Slione ejectors, 079

Silt chambers. 623

Washington pumping station, 703
Siphons, 580

for flush-tank, 589

formed by setting of pump, 672

inverted, sec Inverted siphons
Slants, construction with cement pipe, 353

spacing in Philadelphia. 42
Slope, effect of — on run-off, 290

of sewers. 48, 106, 114
Sludge, forms more quickly in salt than fresh
w^ater, 112

minimum velocitira to prevent deposit
of. 114
Smith, C. X>.; values of Kutter's n, 82
Smith, Dr. Angus; pipe coatings, 368
Smith, Hamilton, Jr.; discharge of circiUar
and square orificos, 129, 130

weir formula, 136
Smith, J. Waldo; CatskiU aqueduct section.

442
Snow, dumped into catch-basins, 523

effect on floods, 256
Somerville, Mass.; density of population,

100
Southbridge, Mass., volume of sewage, 189
Specifications, castings, 529

cast-iron pipe, 341

vitrified clay pipe, 349
Spencer, Mass., volume of sewage, 189
Spokane, Wash., intensity of rainfall. 227
Springfield, Mass., pipe coating, 368

riveted steel water pipe, 366
Spring Valley Water Co., pipe coating

experience, 369
Stability of sewer sections, merits of

different types, 4U2
Stearns, Frederic P., report on Baltimore
sewers, 16

Sudbury aqueduct gagings, 91

values of Kutter's n. 88

Wachusett aqueduct section, 437

weir formula, 1.36
Steel, for pipes. 'MM\
Steps for manholes, 553
Stevens continuous water-stage recorder.

304
Stewart. Henry L.; wood-stave pipe. 38U
Still box in gaging, 132, 307
Stockbridge, Mass., volume of sewage. 1S»
Stockton, Cal.; minimum, grades, 120
Storage, effect on pumping, 647

in s<'wers and on streets, effect of, 271

tanks, 719
Storm overflows, see overflows, storm

effect on hydraulic gradient, ."VO

ex.'imple.H of computations, 54, 57, t'lO.S

general features, 52, (>07
Storm water, amount in intcrcepters, 52,
205

INDEX

745

Storm water, character, 34, 204
flow of. formulas, 235

in rivers, 249
governs sise of combined sewers, 44
Local Government Board requirements

for treating, 34
measurements, 311
methods of estimating in American

cities, 205
pumped by gas engines at London, 45
rational method of estimating run-off,

263
removal from streets at inlets, 515
Royal Commission on Sewage Disposal's
views on treating, 34
Strainers on suction pipes, 661, 674
Streets, best manhole covers, 554

change from concave to convex cross-
section, 11
cleaning by flushing, 12, 522
flow of water over, 265
inlets for storm water, 515, 530
position of sewers in, 41, 447
ratio of street area to population, 274
water from surface is polluted, 34, 204
Stresses in masonry arches,

analysis by voussoir method, 472
elastic theory, Turneaure's method,

478
elaMtio theory, French's method, 478
analysis of stresses in arch section, 503
Suburbs, estimated growth, 158
Sudbury aqueduct, gagings by Patch, 91

value of Chesy c, 90
Ruilbury River, greatest flood. 258, 259
Suppressed weirs, formula, 136
Susquehanna River, floods, 262
Swuin, George F.; determination of earth
pressures, 468
relative economy of alternative proj-
ects. 646 * •
Syracuse, classification of water consump-
tion, 167
density of population, 161
flushing intake. 584
leaping weirs, 621
manhole bottom. 536
manholf castings. 558
manhole steps, 553
reinforced-concrete pipe, 363
sewage regulators, (K)l
sewer sections, 438, 441, 449
size of interrepter. 184
storrn overflow. 612

T.-ilbot. A. N.; formula for flood flow, 254
rninfall Htudies, 220
stn-iigth of thin elastic rings, 337
tliickness of pipe. 341

Tamping, cement pipe, 351, 353

pressures due to, 334
Tar, pipe coatings, 368, 371, 372
Taunton, Mass.; classification of water
supply, 167

water consumption, 76
Taylor, A. J., sewer gagings at Wilmington.

323
Templeton, Mass., volume of sewage, 189
Terre Haute, Ind.; density of population,

161
Thames; advertisement for plans to abate
nuisance in 1849, 5

Basalgette's explanation to nuisance, 6
Thickness, of arches, empirical formulas, 408

analysis of masonry arches, 471

concrete and reinforced concrete. 407

sewer pipe, 347
Thomson, James; triangular weir experi-
ments, 137
Tide; effect on sewer outlets, 6, 23, 625

flushing sewer at Charleston, 18

flushing sewers at Hoboken, 47

gates, 635
Tillson, George W. ; flushing sewers, 596

mi^hole covers, 556
Time, concentration, 266

required for water to reach sewers, 263
Tompkinsville, N. Y., cast-iron sewer, 374
Topography, effect on a sewerage plan, 34
Toronto, Ont., hourly variations in quantity,
188

Bewer sections, 427
Torricelli's theorem, 66, 128
Track-board, used with current meter, 149
Track, standard railroad, 463
Traction engines, weight. 464
Transporting power of flowing water, 8, 108
Trapezoidal weirs, 138
Traps on catch-basins. 523, 524, 525, 527

on house drains, 641

omitted for ventilation, 2, 645
Trautwine, John C, formula for thicknest

of arches, 410, 412
Trenches, bottom, form in earth, 331

economical dimensions, 401, 547

influence of sise on cross-floction of
sewer, 400

molded pipe for narrow , 362

pressure in, 328
Trenton, N. J., density of population, 160
Triangular weirs, 137
Tribus, Louis L. ; sewer section. 451
Trucks, weight of automobile, 464
Trunk sewers. 44, 296
Truro, P. E. I ; sewer section, 426
Tubi's, capillary, flow through, 71
Tumbling basin, see Drop manhole.
Tunnels, gaging of Chicago water. 92

gaging of Cleveland intake, 93

746

INDEX

Tunnels, tactions of aewer, 426, 427 (pneu>
matio) 432, 440

U

Underdraina, cross-sections illustrating, 426,
427, 432. 435. 436. 438, 440. 441
manholes giving access to, 539
Unwin, W. C; leaping weirs, 621
U-shaped sewer* sections, advantages and
disadvantages, 389
examples, 449

hydraulic elements, 397. 398
Utica. N. Y., flood record. 257

Valves, automatic air valves on steel pipe
sewers, 365
foot, 661. 674
loss in head due to, 69
pump, 659
regulator. 587

special bodira where cutting by sand is
feared. 704
Van Diest. E. C, cement pipe, 353
Velocities, critical, 70

curves of velocities in pipes, 72, 86

in rivers, 74, 76, 87
depositing, 116
formulas for, 76

in sewers, Bazalget's minimum, 7
comparison between circular and egg-
shaped sections, 384
compcnsatiun for curves, 570
erosion of invert^*, 58. 113, 431, 457
transporting power, 8, '108
views of engineers, English, 8
American, 114
maintenance throughout sewerage sys-
tem, 123
mean, maximum and surface, 106
relation to grade, 106
Vena contracta, 128
Ventilation of sewers, 640

omission of traps in early systenis, 2, 25
perforated manhole covers, 556
pumping station, OOo
Htorage basins. 048
Venturi, J. B., discharge through expanding

nozzle. 188
Venturi meter, 138

recorder used in s<^^' age-flow regulator,
606
Vincennes, Ind., minimum grades, 119
Visalia, Cal., inininnim grades, 120
Vitrified clay pipe; see Pipe, vitrified day.
Volume of sewage; see Sewage, volume of.
Voussoir method of analyzing arches, 472

W

Wachuaett aqueduct, croas-section, 436
discharge of, 89

hydraulic elements of aeotion, 395. 397
Waite, H. M.; Cincinnati sewerage. 158
Waltham, Mass., pumping station, 692

water consumption, 176
Waring. Col. George E., Memphis sewerage
system, 24
Omaha sewerage design, 21
Washington, D. C, concrete used for large
sewers in 1885, 16
different types of pipe sewers, 357
heavy rainfall. 268
outlet, 634

protection of low districts, 38
pumping station, 701
sewage regulators, 601
sewer gagings, 323
sewer sections. 391, 433, 435. 449
silt chamber. 625
tide gates, 639

two laterals in wide streets. 41
use of McMath's run-off formula, 249
water consumption. 168
Water, compressibility and elastiotty. 62
flow in pipes, 68
hammer. 330. 341
instruments for recording water levels.

302
intensity of pressure, 65
molecular changes, 62
required for flushing sewers. 595
supply, changes in annual consumption.
170
consumption in different parts of a

city, 107
effect of meters on consumption, 170
fluctuations in daily consumption,

175
proportion reaching sewers, 166
ratio of conHumption to volume of
sewage, IKO
transporting power, 109
weight, 68
Waterbury, Conn.; decision regarding sew-
age (ii!*posal. 31
sewer sections, 436
Waterloo, England; cast-iron outfall sewer,

375
Wat8on. H. S.; utility of catch-basins. 522
Waycrosw. Ga.; flat grades, 118
Webber, William O.; efficiency of centri-
fugal pumps, 000
loHses of head in specials, 09
Webster, George S.; locution of separate
Kew«T.>», 42
section of sewers, 422, 423, 431, 439.
442, 451

INDEX

747

Webster, sewer gagings at Philadelphia, 324
Webster, Albert L. ; pumping station, 685
Weirs, 131

leaping. 618

storm overflows, 608
Weisbach, formula for pipe flow, 78
Weld, F. F.; thickness of arches, 408
Wellesley, Mass., classification of water

supply, 167
Wellholes. 44

Cleveland, 545

Brooklyn. 545

Minneapolis, 545
Wells, angle. 550

, polluted by sewage in Baltimore, 15
Westboro, Mass., leakage into sewers, 186

volume of sewage, 189
Weston aqueduct, mortar lining of steel

pipe, 373
Wicksteed; velocity in sewers, 8
Wiggin, Thomas H.; groined roofs, 649
Wilkes-Barre, Pa., density of population,

160
Willia^, Benezette; separate sewerage

system at Pullman, 24
Williams, Gardner S.; flow through capil-
lary tubes, 71

Haxen and Williams* formula. 101

velocity curves in 30-in. pipe, 73
Williams, Wm. F., sewer section, 439
Wilmington, Del., density of population, 160

■ewer gagings, 323

■ewer sections, 427, 443

water consumption, 168
Wind, effect on rain-gagings, 218
Winnipeg, Man., concrete manhole. 538

flush-tank, 592

use of McMath's run-off formula, 249

Winslow, C.-E. A.; sewer air, 642
Winona, Minn.; raising sewage by ejectors,

679
Wise & Watson; gaging manholes, 550
. Wisner, G. M.; changes in population of
Chicago, 163
sewer section, 444
Wissahickon Creek, Philadelphia, greatest
flood. 258
inverted siphon. 580
Woburn, Mass., water consumption. 176
Wood-stave pipe, 376
Woonsocket, R. I.; inverted siphon, 575
Worcester, Mass., cross-sections of sewers,
430, 432, 454
erosion of inverts, 457
experience with Shone ejectors, 681
hourly variation in sewage volume, 188
measurements of depositing velocities,

117
proportion of water supply reaching

sewers, 166
sewage treatment works, 29
storm water, estimation of. 295
water consumption. 168, 170. 176
Worth, John E.; erosion of sewer inverts,

461
Worthen, William E., used relief map in
planning Brooklyn intercepters, 37

Yellow fever, Memphis, Tenn., 24

Yonkers. N. Y., classification of water con-
sumption, 167

Youghiogheny River, floods. 262

Youngstown, Ohio, density of population,
161

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