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WORKS    OF   PROF.  H.   N.  OGDEN 

PUBLISHED    BY 

JOHN   WILEY    &    SONS 


Sewer  Construction. 

8vo.  xii  +  335  pages,  192  figures.     Cloth,  $3.00. 

Sewer   Design. 

12mo,  xi  +  234  pages,  54  figures,  5  platen.     Cloth. 
82.00. 


SEWER  CONSTRUCTION 


BY 
HENRY    N.  OGDEN,  C.E. 

ASSOC.  MEM.   AM.  SO< 

PROFESSOR    OF    SANITARY    ENGINEERING,    CORNELL   UNIVERSITY 
SPECIAL   ASST.    ENGINEER,    N.  Y.    STA  1  I      ! 
OF   HEALTH 


FfRST  EDITION 

FIRST    THOUSAND 


NEW  YORK 

JOHN    WILEY   &    SONS 

LONDON:    CHAPMAN   &   HALL,  LIMITED 

1908 


COPYRIGHT,    1908, 

BY 
HENRY   N.  OGDEN 


Stanbope  ipreea 

F.    H.   GILSON     COMPANY- 
BOSTON.     U.S.A. 


PREFACE 


THE  following  pages  comprise,  in  a  somewhat  amplified  form, 
a  course  of  lectures  given  in  the  College  of  Civil  Kn^iiu-rring, 
Cornell  University. 

The  course  is  an  elective  one,  intended  for  students  whose-  pur- 
pose to  enter  the  field  of  Sanitary  Engineering  calls  for  more  special 
and  detailed  work  than  is  required  of  all  civil  engineering  student-. 

The  illustrations  of  the  classroom,  made  possible   by  a  a 
of  lantern  slides,  a  portion  of  which  only  have  been  repnxliu •< •«!, 
are  accompanied  by  abundant  explanation  brought  out  by  qi; 
tions  and  answers —  a  feature  not  possible  to  repeat  in  this  present 
volume.     It  is    hoped,  however,  that  sufficient    detail  has  bt •«  n 
given  to  make  clear  the  examples  of  current  practice  which 
offered. 

The  course  represents  the  second  part  of  a  year's  work,  of  which 
the  book  on  " Sewer  Design,"  already  published,  is  the  first  part, 
and  it  is  assumed  that  the  reader  is  familiar  with  that  volume. 
Wherever  serious  omissions  from  the  present  text  have  been  made 
on  that  account,  references  have  been  given  so  that  duplication 
may  be  avoided. 

It  is  believed  that  due  acknowledgment  has  been  made  to  the 
various  books  and  periodicals  and  to  the  reports  of  the  promi- 
nent engineers  and  city  officials  from  which  this  monograph  has 
been  prepared,  and  it  is  hoped  that  the  collection  and  unification 
of  this  scattered  material  may  not  only  aid  the  students  entering 
upon  the  investigation  of  sewer  construction,  but  may  also  be  of 
some  service  to  practicing  engineers  who  may  have  occasion  to 
take  up  the  matter  of  sewer  work  for  the  first  time. 

A  small  number  of  the  illustrations  have  no  references  cited, 
due  to  the  fact  that  they  were  filed  among  the  author's  notes  at 


iv  PREFACE 

various  times  without  mention  of  the  source,  and  an  extended 
search  has  not  been  able  to  locate  them.  They  have  nevertheless 
been  included  because  they  have  proved  useful  in  classroom 
work. 

Special  acknowledgment  is  made  to  the  volumes  of  Engineer- 
ing News,  Engineering  Record,  and  Municipal  Engineering,  from 
which  examples  of  construction  have  been  freely  taken,  the  figures 
however,  having  all  been  redrawn.  Examples  of  costs  have  bivn 
taken  from  current  volumes  of  Engineering-Contracting,  where 
most  valuable  data  on  the  cost  of  engineering  work  is  to  be  found. 
Thanks  are  due  to  the  Eureka  Machine  Company  of  Jackson, 
Mich.,  to  the  C.  W.  Raymond  Company  of  Dayton,  Ohio,  to  the 
Turner,  Vaughn,  and  Taylor  Company  of  Cuyahoga  Falls,  Ohio, 
and  to  the  Carson  Trench  Machine  Company  of  Boston,  Mass., 
for  the  loan  of  cuts  from  which  figures  i,  2,  3,  190,  and  192  have 
been  made.  The  cut  of  the  Moore  Machine  was  made  from  a 
photograph  kindly  furnished  by  Mr.  Thos.  F.  Moore,  president 
of  the  Moore  Machine  Company. 

The  comments  on  the  clauses  of  the  specifications  and  contract 
in  the  chapter  of  that  title  are  based  on  the  exposition  of  parallel 
phrases  as  set  forth  in  Wait's  " Engineering  Jurisprudence,"  and 
due  acknowledgment  is  hereby  made  to  the  author  of  that  valuable 
treatise.  This  chapter  has  been  submitted  to  Professor  E.  H. 
Woodruff  of  the  College  of  Law,  Cornell  University,  and  to  Alec 
H.  Seymour,  Esq.,  legal  adviser  to  the  New  York  State  Department 
of  Health,  to  whom  the  thanks  of  the  author  are  most  cordially 
extended. 


CONTENTS 

CHAPTER  I.    TERRA-COTTA  PIPE. 

Man 

The  manufacture  and  composition  of  sewer  pipe.  Commercial  sizes. 
Cross-sections.  Standard  lengths.  Thickness  of  pipe.  Double- 
strength  pipe.  Standard  and  deep-and-wide  sockets.  Corruga- 
tions   1-12 

CHAPTER  II.    TERRA-COTTA  PIPE  (continued). 

Strength  of  pipe.  Early  tests.  Howe's  experiments.  Barbour's  testa 
and  formula.  Average  breaking  loads.  Records  of  failures  in 
tivnches.  Cement  joints.  Substitutes  for  cements.  Other 
forms  of  joints 13^28 

CHAPTER  III.    BRICK  SEWERS. 

Kinds  of  brick.  Invert  blocks  and  their  value.  Quantity  of  brick- 
work for  different  sizes.  Proper  thickness  of  sewer  walls.  Earth 
pressures  of  sewer  arch.  Sections  adopted  in  Washington,  Ottawa, 
New  Orleans,  Denver,  Brooklyn  and  Rochester.  Bond  in  sewer 
work.  General  considerations 29~5l 

CHAPTER  IV.    CONCRETE  SEWERS. 

Chenoweth  and  Ransome  processes.  Cement  pipes.  Arch  blocks  of 
concrete.  Examples  of  concrete  sewers  at  Chicago,  New  York, 
Victoria,  Truro  and  Swampscott.  Sections  from  Blaw  Centering 
Co 52-66 

CHAPTER  V.    CONCRETE  AND  BRICK  SEWERS. 

The  propriety  of  their  use.    Examples  of  construction  at  Medford, 

Altoona,  Melbourne  and  Boston 67-74 

CHAPTER  VI.    REINFORCED  CONCRETE  SEWERS. 

Examples  with  steel  mesh  at  Mexico  City,  Providence,  Wilmington  and 
Harrisburg.  The  Jackson  reinforced  pipe.  Examples  with  steel 
rods  at  Jersey  City,  New  York,  Des  Moines,  St.  Louis,  Phila- 
delphia, South  Bend  and  Cleveland 75~88 


vi  CONTENTS 

CHAPTER  VII.    MANHOLES. 

PAGES 

The  location,  cross-section  and  size  of  manholes.  The  construction  of 
foundation  and  bottom.  The  proper  thickness  of  manhole  walls. 
High  level  laterals  and  their  connection.  Frames  and  covers. 
Locks  and  dirt  pans.  Lamp  holes 89-112 

CHAPTER  VIII.    CATCH-BASINS. 

Location  and  use  of  catch-basins.  Gratings  and  traps.  Examples  of 
basins  at  Columbus,  Providence,  Margate,  Michigan  City, 
Boston,  Wilmington,  Peoria,  Burlington,  Philadelphia,  Washing- 
ton, Louisville,  Warsaw,  Tarry  town.  Maintenance  of  catch- 
basins 113—132 

CHAPTER  IX.    SIPHONS. 

Examples  of  direct  siphons  at  Norfolk  and  Breslau.  Bridge  crossings. 
Inverted  siphons.  Examples  of  their  use  at  Roanoke,  Newton, 
New  Orleans,  Woonsocket,  Springfield,  New  York,  Ithaca,  Buenos 
Ayres,  Los  Angeles  and  Providence.  Auxiliary  devices.  133-152 


CHAPTER  X.    SCREENS. 

The  function  and  location  of  screens.  Proper  area  of  screens. 
Examples  of  screen  chambers  at  Boston,  Ithaca,  Manchester, 
and  Providence.  Mesh  screens,  rod  screens,  and  plate  screens. 
Examples  of  screens  at  White  Plains,  Marlborough,  Cranston, 
Wayne,  Newark,  Providence,  Pullman,  Richmond  and  Bir- 
mingham   153-169 


CHAPTER  XL    STORM-WATER  OVERFLOWS  AND  REGULATORS. 

Proper  location  of  storm  overflows.  Example  at  Rochester.  Leap- 
ing weir.  Its  theory  with  example  of  its  use  at  Milwaukee. 
Overflow  weirs.  Examples  at  Cleveland,  Providence  and 
Rochester.  Regulators.  Examples  at  Boston,  Worcester, 
Harrisburg,  Brookline  and  Woburn 170-184 


CHAPTER  XII.    BELL  MOUTHS. 

The    description    of    bell    mouths   and    a   discussion  of  their  use. 
amples  at  Philadelphia,  Boston  and  Providence.      Alternate 
construction 185-194 


CONTENTS  vii 

CHAPTER  XIII.     I  OUNDATIO 


Plank  and  gravel  footings.     Woodm  platform^  and  cradles.     Con- 
crete  foundation.-.      Piling.      Examples  of  pili-   foundation 
Cambridge,  Lynn,   Troy,  Boston,  New  York,  St.  Paul.     Allow 
ance  for  settlement  at  Boston 195-210 


CHAPTER  XIV.     OUTFAI.I.  SI-.WKRS. 

Outlet  through  high  bank.  Example  at  Niagara  Falls.  OutK-t 
into  shallow  water.  Examples  at  Harrisburg  and  Bing- 
hamton.  Outlet  into  tidal  waters.  Examples  at  Philadrl- 
phia,  Boston,  New  York,  and  New  London.  ProUvtion  from 
erosion.  Examples  at  Burlington  and  Los  Angeles 211-226 


CHAPTER  XV.    HOUSE  ('<>\\i<  noNS. 

Y  and  T  branches.  Records  of  location.  Size  of  house  drain. 
Connections  with  deep  sewers.  Two-story  lines.  In  rock 
trenches 227-234 


CHAPTER  XVI.    SURVEYING. 

Location  of  sewer  line.    Location  of  manholes.    Offset  line.    Grade 

boards.     Field  notes.     Estimates.     Records  of  branches 235-244 


CHAPTER  XVII.     TREN<  HINT.. 

Width  of  trenches.  Sheeting.  Conveying  machines.  Carson,  Lid- 
gerwood  and  Moore  machines.  Rock  trenching.  Drilling  and 
explosives 245-256 


CHAPTER  XVIII.    ESTIMATES  AND  COSTS. 

Earth  excavation,  back-filling,  ramming.  Rock-work.  Sluvting. 
Tunnel-work.  Vitrified  pipe.  Brickwork.  Conm-tr.  Man 
holes.  Iron  castings.  Flush-tanks.  Engineering 257-278 


CHAPTER  XIX.     SPECIFICATIONS  AND  CONTRACTS. 
Typical  form  of  contract  and  specifications,  with  comments  thereon,     270-323 


LIST  OF  FIGURES 

FIGURE 

1.  Pug  mill 3 

2.  Roll  mill .  .  4 

3.  Pipe  press 

4.  Pipe  die 6 

5.  Bell  and  spigot  pipe 9 

6.  Forms  of  sockets i  a 

7.  Support  for  jointing  pipe 21 

8.  Device  for  holding  jointed  pipe 22 

9.  Molds  for  Stanford  joint 23 

10.  Conical  Stanford  joint  section 27 

11.  Spherical  Stanford  joint  section 27 

12.  Archer  joint 27 

13.  Hassal  joint 27 

14.  Sykes  joint 28 

15.  Brick  section  in  New  York 30 

16.  Joints  in  brick  sewer 31 

17.  Invert  blocks  of  American  Sewer  Pipe  Co 32 

18.  Talbot's  invert  block 32 

19.  Latham's  invert  block 33 

20.  Babcock's  invert  block 33 

21.  Equilibrium  polygon  in  Philadelphia  section 38 

22.  Equilibrium  polygon  in  Philadelphia  section 39 

23.  Equilibrium  polygon  for  different  loadings 40 

24.  Egg-shaped  section  at  Washington,  D.C 41 

25.  Egg-shaped  section  at  Washington,  D.C 42 

26.  5-foot  9-inch  sewer  on  piles 43 

27.  7-foot  sewer  at  Ottawa,  Canada 43 

28.  6-foot  sewer  at  New  Orleans,  La 44 

29.  94-inch  sewer  at  Denver,  Colo 46 

30.  Egg-shaped  sewer  at  Rochester,  N.Y 46 

31.  Basket-handle  section  at  Rochester,  N.Y 47 

32.  Row-lock  bond  for  brickwork 48 

33.  Headers  for  bonding 49 

34.  Strap  iron  reinforcement 49 

35.  Concrete  reinforcement  at  Washington,  D.C 58 

36.  Concrete  sewer  at  Chicago 59 

37.  Sewer  along  New  York  subway 60 

38.  Concrete  sewer  at  Victoria,  B.C 60 

39.  Brick  and  concrete  sewer  at  Truro,  N.S 61 

40.  Forms  used  at  Truro,  N.S 62 

41.  Concrete  sewer  at  Swampscott,  Mass 

42.  Sections  from  catalogue  of  Blaw  Collapsible  Steel  Centering  Co..  64 

43.  Sections  from  catalogue  of  Blaw  Collapsible  Steel  Centering  Co.. .  .  65 

44.  Brick  and  concrete  sewer  at  Medford,  Mass 67 

ix 


x  LIST  OF  FIGURES 

FIGURE  PAGB 

45.  Forms  used  at  Medford,  Mass 68 

46.  Brick  and  concrete  sewer  on  platform 69 

47.  Sixty-four-inch  brick  and  concrete  sewer  on  firm  ground 70 

48.  Brick  and  concrete  sewer  at  Altoona,  Pa 71 

49.  Circular  section  of  Melbourne,  Aus.,  outfall 71 

50.  Egg-shaped  section  of  Melbourne,  Aus.,  outfall 72 

51.  Section  of  sewer  with  basket-handle  section 73 

52.  Section  showing  continuous  wood  lagging  for  wet  soil 73 

53.  Section  of  Boston  Aqueduct 74 

54.  Section  of  reinforced  concrete  aqueduct  at  Mexico 76 

55.  Reinforced  concrete  sewer  at  Providence,  R.I 77 

56.  Reinforced  concrete  sewer  at  Wilmington,  Del 78 

57.  Reinforced  concrete  sewer  at  Harrisburg,  Pa 78 

58.  Section  of  reinforced  concrete  aqueduct  at  Jersey  City,  N.J 81 

59.  Reinforced  concrete  sewer,  Borough  of  Queens 81 

60.  Section  of  Ingersoll  Run  sewer,  Des  Moines,  la 83 

61.  Section  of  Harlem  Creek  sewer,  St.  Louis,  Mo 83 

62.  Section  of  McKean  St.  sewer,  Philadelphia 84 

63.  Section  of  sewer  at  South  Bend,  Ind 86 

64.  Section  of  intercepting  sewer  at  Cleveland,  0 87 

65.  Cross-section  of  manhole 91 

65.  Cross-section  of  shallow  manhole 92 

67.  Split  pipe  in  manhole  bottom 92 

68.  Construction  of  manhole  floor 93 

69.  Drawings  of  junction  manhole 95 

70.  Manhole  from  side  of  brick  sewer 97 

71.  Detail  drawing  of  connection 98 

72.  Manhole  over  axis  of  brick  sewer 99 

73.  High  level  connection  at  -Santos,  Brazil 100 

74.  High  level  connection  on  outside  of  manhole 101 

75.  Inclined  connection  from  high  level  sewer 102 

76.  Deep  manhole  at  Melbourne,  Australia 103 

77.  Deep  manhole  at  Cleveland,  Ohio 103 

78.  Slips  in  sewer  at  St.  Louis,  Mo 103 

79.  Manhole  cover  designed  for  Santos,  Brazil 105 

80.  Manhole  cover  built  by  Sessions  Foundry  Co 105 

81.  Manhole  cover  from  Auburn  contract  drawings 106 

82.  Lock  used  at  Ithaca,  N.Y 107 

83.  Lock  used  at  Salt  Lake  City,  Utah 108 

84.  Dirt  pail  designed  for  deep  sewers 109 

85.  Dirt  pail  designed  for  shallow  sewers 109 

86.  Dirt  pan  as  built  at  Ithaca,  N.Y no 

87.  Dirt  pail  from  Baumeister no 

88.  Lampholes  with  concrete  supports 1 1 1 

89.  Lamphole  cover 112 

90.  Location  of  inlets  at  street  corner 114 

91.  Location  of  inlets  at  street  corner 115 

92.  Location  of  inlets  at  street  corner 115 

93.  Flat  top  grating  made  in  Dayton,  Ohio 116 

94.  Circular  flat  top  grating 117 

95.  Circular  dome-shaped  grating 117 

r/>.   !  lorizontal  grating  with  vertical  opening 118 


LIST  OF  FIGURES  xi 

FIGURE  PAGB 

97.  Castings  for  horizontal  grating  with  vertical  opening  .  .  nS 

98.  Grating  for  curb  corner 1 1,, 

99.  Grating  for  straight  curb i  i(J 

100.  Catch-basin  at  Columbus,  Ohio 120 

101.  Catch-basin  at  Providence,  R.I 121 

102.  Catch-basin  at  Margate,  Kng [99 

103.  Catch-basin  at  Michigan  City,  Ind 123 

104.  Cast-iron  hood  for  catch- basin  trap 124 

105.  Catch-basin  at  Wilmington,  Del 125 

106.  Catch-basin  at  Peoria,  111 1 26 

107.  Catch-basin  at  Burlington,  Iowa 126 

108.  Catch-basin  at  Philadelphia,  Pa 127 

109.  Catch-basin  at  Washington,  D.C 128 

no.  Catch-basin  at  Louisville,  Ky 129 

in.  Inlet  at  Warsaw,  N.Y 130 

112.  Inlet  at  Tarrytown,  N.Y 131 

113.  Direct  siphon  at  Norfolk,  Va 134 

114.  Bridge  designed  for  sewer  crossing 136 

115.  Inverted  siphon  at  Roanoke,  Va 138 

116.  Inverted  siphon  at  Newton,  Mass 139 

117.  Inverted  siphon  at  New  Orleans,  La 141 

118.  Inverted  siphon  at  Woonsocket,  R.I 143 

119.  Inverted  siphon  at  Springfield,  Mass 144 

120.  Inverted  siphon  under  New  York  subway 145 

121.  Inverted  siphon  designed  for  Ithaca,  N.Y 146 

122.  Inverted  siphon  at  Buenos  Ayres 147 

123.  Inverted  siphon  at  Providence,  R.I 149 

124.  Detail  of  inverted  siphon  at  Ithaca,  N.Y 150 

125.  Screen  chamber  for  Boston  sewer 155 

126.  Screen  chamber  for  Ithaca  sewer 155 

127.  Screen  chamber  at  Manchester,  Eng 158 

128.  Screen  chamber  at  Providence,  R.I 160 

129.  Rectangular  mesh  screen  at  White  Plains,  N.Y 160 

130.  Rectangular  mesh  screen  at  Marlborough,  Mass 161 

131.  Basket  mesh  screen  at  Cranston,  R.I 162 

132.  Horizontal  mesh  screen  at  Wayne,  Pa 163 

I33-  Vertical  iron-rod  screen  at  Ithaca,  N.Y 165 

134.  Wooden  slat  screen  at  Providence,  R.I 166 

135.  Tank  screen  at  Pullman,  111 167 

136.  Mechanical  cleaning  rake  at  Richmond,  Va 168 

137.  Movable  screen  at  Birmingham,  Eng 169 

138.  Location  of  overflows,  Rochester  trunk  sewer 171 

139.  Leaping  weir  at  Milwaukee i  73> 

140.  Parabolic  path  over  leaping  weir 

141.  Overflow  weir  at  Cleveland,  Ohio i  75 

142.  Overflow  weir  at  Providence,  R.I i?7 

143.  Overflow  weir  at  Rochester,  N.Y 1 7** 

144.  Automatic  regulator  at  Boston,  Mass 1 79 

145.  Automatic  regulator  at  Worcester,  Mass 180 

146.  Automatic  regulator  at  Harrisburg,  Pa 181 

147.  Automatic  regulator  at  Brookline,  Mass 182 

148.  Regulating  device  of  Coffin  Valve  Co 183 


xii  LIST  OF  FIGURES 

FIGURE  PAGH 

149.  Automatic  regulator  at  Woburn,  Mass 184 

150.  Sections  of  bell-mouth  intersection 186 

151.  Bell-mouth  sections  at  Philadelphia,  Pa 188 

152.  Bell-mouth  sections  at  Boston,  Mass 189 

153.  Bell-mouth  sections  at  Boston,  Mass 190 

154.  Photograph  of  Providence  bell-mouth 191 

155.  Bell-mouth  cover  of  | -beams  with  vertical  walls 192 

156.  Perspective  sketch  of  sewer  junction  at  Minneapolis,  Minn 193 

157.  Wooden  cradle  for  brick  or  concrete  sewer 197 

158.  Ten-inch  pipe  supported  on  piles 199 

159.  Eighteen-inch  pipe  supported  on  piles 200 

160.  Egg-shaped  sewer  on  piles  at  Cambridge,  Mass 201 

161.  Egg-shaped  sewer  on  piles  at  Lynn,  Mass 202 

162.  Egg-shaped  sewers  on  piles  at  Troy,  N.Y 203 

163.  Wooden  barrel  supported  on  piles 204 

164.  Basket-handle  sections  on  piles  at  Boston,  Mass 205 

165.  Rectangular  section  on  piles  at  New  York,  N.Y 206 

166.  Rectangular  section  on  piles  at  St.  Paul,  Minn 207 

167.  Cross-section  of  Moon  Island  embankment,  Boston,  Mass 208 

1 68.  Curves  of  settlement,  Moon  Island  embankment,  Boston,  Mass. .  .  209 

169.  Protection  wall  and  flap  valve  for  outlet 212 

170.  Submerged  outlet  at  Binghamton,  N.Y 213 

171.  Outlet  pipe  in  high  bank 214 

172.  Outlet  pipe  down  bluff  at  Niagara  Falls,  N.Y 215 

173.  Section  of  outlet,  Aramingo  Canal  sewer,  Philadelphia 215 

174.  Outlet  sewer,  South  Metropolitan  District,  Boston 217 

175.  Section  of  outlet,  Broadway  outfall  sewer,  New  York 218 

176.  Outlet  sewer  at  Spring  Lake,  N.  J 219 

177.  Section  of  wooden  outlet,  New  London,  Conn 220 

178.  Photographs  of  construction  of  Ithaca  wooden  outlet 221 

179.  Bank  protection  at  Burlington,  Iowa 223 

1 80.  Steel  outfall  pipe  at  Toronto,  Canada 225 

181.  V  branch  with  |  bend  for  house  connection 228 

182.  Sketch  to  record  location  of  V  branches 229 

183.  T  branch  for  connections  with  deep  sewers 231 

184.  V  branch  for  connections  with  deep  sewers 232 

185.  Double  V  branch  for  connections  with  deep  sewers : 233 

1 86.  Sketch  snowing  location  of  offset  stakes 237 

187.  Sketch  showing  method  of  supporting  grade  boards 239 

188.  Sketch  showing  method  of  supporting  grade  boards 239 

189.  Sketch  showing  method  of  driving  sheeting 247 

190.  Perspective  sketch  of  Carson  trench  machine 249 

191.  Perspective  sketch  of  Lidgerwood  cableway 251 

192.  Photograph  of  Moore  conveying  machine 253 


SEWER  CONSTRUCTION 


CHAPTER  I. 
SEWER   PIPE. 

DURING  the  slow  development  which  has  taken  place,  not  only 
in  the  design  of  sewers,  but  also  in  the  details  of  their  construction, 
many  kinds  of  material  and  many  forms  of  cross-section  have 
been  used,  and  a  great  difference  in  the  care  displayed  in  the  work 
itself  has  resulted.  Stone,  brick,  wood,  concrete,  cement  pipe, 
terra  cotta  pipe,  and  even  iron  pipe  have  all  been  used.  Sewers 
have  been  made  rectangular,  horse-shoe  shaped,  triangular,  oval, 
egg-shaped,  and  circular.  They  have  been  built  of  rough  field 
stone,  without  mortar,  and  of  paving  brick  with  cement  mortar. 
They  have  been  rough  on  the  inside  and  smoothly  plastered  on 
the  outside,  and  vice  versa.  In  the  course  of  years,  however, 
engineering  practice  has  become  crystallized,  and  engineers  have 
generally  adopted  circular  glazed  terra  cotta  or  vitrified  sewer 
pipe  as  the  standard  conduit  for  all  sewers  under  24  inches  in 
diameter.  A  large  quantity  of  30  and  36-inch  pipe  is  also  used, 
but  with  that  size  the  practice  is  not  so  well  established.  For  still 
larger  sizes,  brick  or  concrete  is  used,  either  separately  or  together, 
according  to  the  judgment  of  the  engineer. 

The  chief  reason  for  the  general  adoption  of  vitrified  terra  cotta 
sewer  pipe  is  probably  cheapness,  although  it  has  the  great  addi- 
tional advantage  of  having  an  impervious  surface  not  affected  by 
acids  or  steam,  and  not  abraded  by  silt  in  suspension.  The 
disadvantages  are  two:  first,  that  it  is  impossible  to  prevent  leak- 
age through  the  joints;  and  second,  that  such  pipe  has  only  a 
limited  strength,  and  must,  therefore,  be  handled  carefully,  and 


2  SEWER   CONSTRUCTION 

be  thoroughly  bedded  in  place.  Compared  with  stone  or  brick, 
such  pipe  has  the  further  advantage  which  comes  from  a  smooth 
interior,  viz.,  a  greater  discharging  capacity  for  the  same  grade, 
an  advantage  which  will  be  discussed*  later.  It  is  not  entirely 
satisfactory  for  the  two  reasons  above  named,  and  specifications 
are  worded  to  minimize,  as  far  as  possible,  the  inherent  defects  of 
the  material.  The  manufacturer,  however,  is  only  able  to  reach 
his  standard,  and  the  specifications  must  be  a  compromise  between 
the  wishes  of  the  engineer  and  the  present  possibilities  of  the 
manufacturer.  To  make  these  limitations  clear,  the  following 
description  of  the  method  of  manufacture  is  given,  followed  by  a 
discussion  of  the  strength  of  the  manufactured  article.1 

Roughly  speaking,  vitrified  terra  cotta  pipe  is  made  like  brick, 
of  burned  clay,  but  the  process  is  more  intricate.  The  clay  must 
be  better,  that  is,  a  purer  silicate  of  alumina,  yet  with  more  fluxing 
agents,  and  there  must  be  a  proper  admixture  of  sand  and  loam, 
or  of  old  burned  pipe,  in  order  to  give  toughness  and  prevent 
excessive  and  irregular  shrinkage  in  burning.  The  temperature 
of  the  kiln  must  be  higher,  and  the  various  processes  of  drying, 
heating,  burning,  and  cooling  must  be  more  carefully  regulated 
than  in  the  manufacture  of  brick.  In  some  plants  a  careful  pro- 
portioning by  weight  of  the  various  ingredients  is  made,  while  in 
others  the  manager  or  foreman  mixes  two  or  more  piles  by  barrow- 
fuls  in  such  a  way  as  his  experience  dictates.  The  plant  at 
St.  Louis  is  reported  to  use  material  as  follows :  Fire  clay,  40  per 
cent;  surface  soil,  40  per  cent;  yellow  clay,  15  per  cent;  burnt  pipes, 
5  per  cent.  The  analyses  on  the  following  page  are  taken  from 
Ries'  "Clays,"  1906,  and  show  the  composition  of  the  clays  from 
which  pipe  is  made  in  various  parts  of  the  United  States. 

A  plant  at  Portland,  Me.,  uses  a  clay  mined  in  New  Jcrsrv, 
brought  by  boat  to  the  factory  and  there  mixed  with  the  native 
clay  and  a  small  proportion  of  burnt  pipe,  finely  ground. 

Probably  any  clay  which  is  known  to  make  good  vitrified  brick 

1  Eng.  News,  Vol.  10,  p.  329;  Mun.  Eng.  Vol.  9,  p.  280.  Eng.  News,  Vol.  27, 
p.  624;  U.  S.  Geological  Survey,  i8th  Ann.  Rep.  Pt.  5,  p.  1105.  Eng.  News, 
Vol.  28,  p.  473;  Brick,  May  i,  and  June  i,  1899. 


SEWER  PIPE  3 

would  make  pipe  as  well,  and  in  fact  many  factories  make  both 
pipe  and  brick  with  the  same  raw  material. 

ANALYSES  OF  SEWER  PIPE  CLAYS. 


Silica 

5:7    10 

r-    60 

6?   oo 

e-}    06 

Alumina               

21     2O 

24    34. 

27     C7 

I  ^    ?6 

j  /  -u^ 

Ferric  oxide  
Ferrous  oxide 

7-31 

6.  II 

1.87 

46 

7.72 

3-4i 

Lime    

•  20 

.42 

44 

60 

•/u 
60 

Alagnesia 

I     ^  3 

77 

80 

Co 

Potash 

311 

3OO 

2    4O 

3  66 

•j    57 

Soda 

'2 

OI 

OQ 

2O 

v3  O/ 

Titanium  oxide    

I     IO 

•UJ 

8^ 

Water     

6.00 

6  75 

6  4S 

7    73 

7    27 

Moisture  

i  .30 

2  .6? 

86 

Sulphur  trioxide 

77 

Phosphoric  pentoxide 



Total 

08  87 

on    74 

100  47 

07    06 

100  67 

In  all  cases  the  clay  has  to  be  worked  up,  that  is,  so  spaded  and 
cut  up  as  to  make  a  mass  of  uniform  moisture  and  density  alone, 
and  then  with  the  burned  pipe  or  grog. 


Fig.  i 

The  most  recent  plants  use  the  common  pug  mill  (see  Fig.  i  )* 
for  this  purpose,  wheeling  or  conveying  the  clay  into  the  mill  at 

1  From  Catalogue  of  Eureka  Machine  Company,  Jackson,  Mich. 


4  SEWER  CONSTRUCTION 

one  end  and  catching  it  at  the  other  for  another  mixing  in  the 
same  or  another  mill.     The  large  roll  mills  (see  Fig.  2)1  formerly 


Fig.  2 


used,  are  mills  in  which  the  clay  is  deposited  in  a  large  dish  or  pan 
about  ten  feet  in  diameter;  a  vertical  spindle  in  the  center  carries  a 
horizontal  bar  which  extends  across  the  pan  and  is  revolved  about 
the  spindle  by  suitable  bevel  gearing.  On  the  horizontal  bar  are 
two  symmetrically  placed  cylindrical  rolls  of  cast  iron  about  four 
feet  in  diameter,  weighing  three  tons  each.  The  outer  edge  of  the 
pan  is  perforated  so  that  the  powdered  clay  can  pass  through, 
while  the  coarser  portions  are  being  continually  thrown  back  by 
guides  under  the  rolls.  Such  a  mill  answers  admirably  for  break- 
ing down  old  pipe,  but  clay  which  has  been  in  the  open  air  is  too 
wet  and  tenacious  to  be  thoroughly  broken  up.  For  this  reason 
the  pug  mill  is  preferred.  The  well-ground  clay  with  its  admix- 

1  From  Catalogue  of  C.  W.  Raymond  Company,  Dayton,  Ohio. 


SEWER  PIPE 


T5To.4  Sewer  Pipe  Press. 
Steam  Cylinder  44 'x  50" 
Clay  Cylinder  2o"x  56" 


SEWER  CONSTRUCTION 


ture  of  grog  when  in  a  proper  state  of  moisture  is  brought  finally 

by  an  elevator  to  the  top  of  the  press  which  forms  the  pipe. 

(See  Fig.  3.)1 
The  press  consists  essentially  of  two  parts :  the  steam  cylinder, 

three  to  four  feet  in  diameter,  and  the  mud  cylinder  underneath, 

about  twenty  inches  in  dia- 
meter. The  pistons  of  the 
two  cylinders  are  direct-con- 
nected usually  by  three  piston 
rods.  The  clay  or  mud  is 
delivered  into  the  mud  cylin- 
der automatically  at  each  up 
stroke,  one  charge  being  suffi- 
cient to  make  several  pipes  of 
the  smaller  sizes.  To  form 
the  pipe,  the  lower  end  of 
the  mud  cylinder  has  attached 
to  it  the  die  for  the  particular 
sized  pipe  to  be  made.  (See 

Fig.4-)2 

The  die  is  of  cast  iron, 
bolted  by  flange  joints  on  to 
the  mud  cylinder,  and  so 
shaped  that  the  mud  forced 
against  it  takes  the  form  of 
the  socket  of  the  pipe.  Above 
the  socket-former,  or  lower 
end  of  the  die,  a  straight 
cylindrical  portion  serves  to 
shape  the  body  or  straight 
part  of  the  pipe.  Inside 


Die 


Fig- 4 


the  die  is  a  cast   iron   bell, 


the  outside  of  which  forms  the  inside  of  the  pipe  bell  and  the 

1  From  Catalogue  of  the  Turner,  Vaughn    &  Taylor  Company,   Cuyahoga 
Falls,  Ohio. 

2  From  Eng.  News,  Vol.  27,  p.  624. 


SEWER  PIPE  7 

pipe.  In  operation,  the  mud  cylinder  being  filled,  steam  is 
admitted  above,  which  forces  the  mud  down  between  the  bell 
and  the  socket  former,  the  escape  of  the  mud  being  prevented  by 
the  table  on  which  the  bell  stands.  This  table  is  then  lowered 
slowly,  the  pressure  being  continued,  and  the  mud,  squeezed  out 
between  the  bell  and  the  die,  forms  the  hollow  cylindrical  pipe. 
When  of  proper  length  the  pipe  is  cut  off  and  is  then  carefully 
set  away  to  dry.  It  can  be  readily  seen  that  the  mud  must  be 
stiff,  in  order  to  stand  up  under  its  own  weight,  and  it  is  found 
that  practically,  even  with  the  stiffest  mud,  a  three-foot  pipe  is 
the  longest  possible.  Any  irregularity  in  mixing  or  in  the 
moisture  tends  to  settle  the  pipe  on  one  side,  giving  a  curve  to  the 
pipe  and  detracting  from  its  value  as  straight  pipe.  All  sizes  of 
pipe  are  made  in  the  same  way,  the  different  diameters  being 
obtained  by  using  different  dies. 

The  pipes  are  dried  in  large  rooms,  heated  by  steam,  the 
process  requiring  from  3  to  15  days,  depending  on  the  weather. 
During  this  time  the  pipes  are  cut  off  to  exact  lengths,  the  edges 
are  rounded,  the  corrugations  are  scratched  on,  and  the  Y's,  T's, 
etc.,  are  formed  or  molded  on  by  hand.  When  the  pipes  are  well 
dried  they  are  wheeled  into  the  kilns,  stacked  on  end,  small  pipes 
inside  larger  ones,  all  resting  on  rings  set  on  the  floor  to  prevent 
excessive  warping  at  that  point. 

The  kilns  are  of  brick,  beehive  shaped,  30  to  40  feet  in  diameter. 
The  bottom  is  formed  of  firebrick  about  three  feet  deep,  so  placed 
as  to  allow  the  passage  of  smoke  and  gases  downward  to  the  flue, 
which  latter  runs  horizontally  under  the  bottom  of  the  kiln  to  the 
chimney  outside.  The  fires  are  built  around  the  outside  between 
the  outside  wall  and  the  fire  wall,  which  is  about  18  inches  inside 
and  rises  to  the  springing  line  of  the  dome,  about  six  feet  up. 
The  hot  gases  in  this  way  do  not  strike  the  pipe  directly,  but  are 
reflected  from  the  roof  downwards,  giving  an  even  heat  through 
the  kiln.  The  time  of  burning  depends  on  the  size  of  the  kiln, 
the  kind  of  clay,  etc.,  but  it  usually  takes  about  five  days,  the 
increase  in  temperature  being  made  very  gradually,  especially 
at  first.  When  the  pipes  have  reached  the  point  of  vitrifaction, 


8  SEWER  CONSTRUCTION 

about  2400°  F.,  salt  in  shovelfuls  is  thrown  on  the  fires,  and  the 
process  repeated  three  or  four  times  an  hour.  The  salt  is  vola- 
tilized in  the  presence  of  moisture,  and  hydrochloric  acid  is  disen- 
gaged, which  in  the  presence  of  the  vitreous  silicates  of  the  clay 
unites  to  form  a  double  alkaline  silicate  or  vitreous  glaze  on  the 
surface  of  the  pipe.  This  glaze  is  a  chemical  union  penetrating  the 
pipe,  and  is  not  a  surface  skin  which  can  scale  off.  It  is  very  hard, 
an  emery  wheel  scarcely  cutting  it,  and  while  it  is  admirable  in  its 
resisting  power  to  abrasion,  it  is  so  hard  and  smooth  that  material 
used  for  joints  adheres  but  imperfectly.  A  barrelful  or  less  of 
salt  is  used  for  a  kiln  20  feet  in  diameter  and  15  feet  high.  Com- 
mon coarse  salt  answers  the  purpose,  the  sweepings  from  packing 
houses  having  been  found  to  be  satisfactory.  The  salting  being 
finished,  the  fires  are  banked,  the  kiln  gradually  cooled  off,  and  in 
four  or  five  days  the  pipes  are  taken  out  ready  for  market.  In 
drying  and  burning,  the  pipes  shrink  about  10  per  cent  in  diameter 
and  in  length,  so  that  each  pipe  is  molded  about  five  forty-eighths 
inch  larger  for  each  inch  of  diameter,  and  10  per  cent  longer 
than  is  required  in  the  final  product.  The  exact  temperature  at 
which  the  salt  is  applied  is  a  matter  of  importance,  and 
while  pyrometers  of  various  sorts  have  been  tried,  dependence  is, 
as  a  rule,  placed  on  the  experience  of  workmen,  who  are  guided 
by  the  appearance  of  small  test  pieces  placed  in  the  kiln  within 
reach.  If  the  pipe  are  overburned,  they  are  brittle,  and  are 
likely  to  have  blisters  formed  in  the  glaze,  especially  with  lime 
in  the  clay;  if  the  pipe  are  underburned,  the  glaze  is  not  well 
formed,  and  the  pipe  lack  strength. 

The  usual  form  of  sewer  pipe  is  the  so-called  bell  and  spigot, 
the  spigot  end  being  merely  the  end  of  the  straight  pipe,  with 
no  rim  as  in  cast  iron  pipe,  and  the  bell  formed  on  to  the 
straight  length  as  shown  in  Fig.  5.1  Egg-shaped  pipe  have  been 
made  in  small  quantities  in  this  country;  and  in  1897  a  pipe, 
circular  on  the  outside  but  with  a  small  channel  formed  inside  of 
the  thick  pipe  to  accommodate  small  flows,  was  patented  in  Eng- 

1  Paving,  Vol.  13,  p.  377.  From  Catalogue  Monmouth  Mining  and  Manufac- 
turing Company. 


SEWER  PIPE  9 

land.1  It  is  probable  that  attempts  to  change  the  form  of  the 
cross-section  will  not  be  successful,  since  any  pipe  except  circular 
would  be  so  warped  in  burning  that  the  proportion  of  unsalable 
pipe  would  be  large,  making  the  cost  of  the  perfect  ones  very 
high. 

Many  forms  of  bells  have  been  made,  all  with  the  attempt  to 
improve  the  water-tightness  of  the  joint.     Pipes  have  been  made 


Fig-  5 


without  bells,  the  joint  being  made  with  rings  or  sleeves.  It  has 
been  claimed  that  better  joints  can  be  made  in  this  way,  but 
their  superiority  has  never  been  proved  by  actual  experience.  In 
England  much  use  has  been  made  of  a  joint  cast  onto  the 
spigot  and  inside  of  the  bell  in  such  a  way  that  a  ball  and  socket 
motion  is  obtained,  allowing  small  changes  in  alignment  to  take 
place  without  breaking  the  joint  or  the  pipe.  Bells  much  larger 
than  the  ordinary  bell  are  required  for  this.  Their  value  will 
be  discussed  under  the  head  of  joints. 

Pipes  are  made  throughout  the  country  of  the  following  com- 

1  Paving,  Vol.  13,  p.  314. 


10  SEWER   CONSTRUCTION 

mercial  sizes,  4,  5,  6,  8,  9, 10,  12, 15,  18,  20,  and  24-inch  diameters, 
and  engineers,  in  designing,  increase  the  size  demanded  by  theory 
so  as  to  use  one  of  the  above  sizes.  It  is  possible,  if  a  large  quan- 
tity of  an  odd  size  is  wanted,  to  have  special  dies  made,  and  the 
pipe  burned  to  order.  Such  a  requirement,  even  if  the  size  of  the 
order  is  such  that  the  manufacturer  is  willing  to  meet  the  cost  of 
the  die,  requires  at  least  a  month  for  the  actual  manufacture,  and 
more,  if  the  factory  is  full  with  orders  for  regular  sizes.  Certain 
firms  make  and  keep  on  hand  other  sizes,  such  as  7,  14,  16,  21, 
and  22-inch  diameters,  but  in  general  it  is  not  wise  to  select  one  of 
these  odd  sizes,  since  it  either  forces  a  contractor  to  buy  from  one 
firm,  shutting  out  other  bidders,  or  else  adds  to  the  price  he  must 
pay  for  the  pipe,  and  increases  the  time  required  for  putting 
material  on  the  ground.  Of  late,  larger  sizes  than  24  inches  have 
been  made,  and  their  use  substituted  for  brick,  especially  for  diam- 
eters of  30  and  36  inches.  Their  adoption  is  to  be  decided  on 
only  after  a  careful  study  of  their  cost  and  of  their  probable 
strength. 

The  standard  length  of  a  sewer  pipe  has  been  two  feet  until 
within  the  past  few  years,  but  now  two  and  a  half  and  three-foot 
lengths  are  generally  available.  Y's  and  T's,  however,  are  still 
made  in  two-foot  lengths  only.  The  advantage  in  the  greater 
length  lies  in  the  reduction  of  the  number  of  joints,  thus  giving  a 
tighter  line  in  wet  ground,  and  no  evidence  is  forthcoming  that  the 
longer  pipes  are  more  likely  to  break  when  once  placed  in  the 
trench.  On  bad  bottom,  where  there  is  danger  of  settlement,  the 
longer  lengths  should  be  more  stable  and  a  better  alignment  thus 
preserved.  The  engineer  is,  therefore,  justified,  since  manufac- 
turers have  proved  their  ability  to  make  three-foot  lengths,  in 
always  specifying  that  dimension. 

The  proper  thickness  of  sewer  pipe  has  been  much  discussed, 
the  relation  of  the  strength  of  the  pipe  to  the  thickness  being 
manifest.  Since  sewer  pipe  do  not  carry  internal  pressure,  the 
method  of  determining  the  thickness  must  be  by  the  other  func- 
tion of  a  pipe,  namely,  to  withstand  external  pressure  —  a  function 
to  which  theory  does  not  readily  lend  its  aid.  The  thickness, 


SEWER  PIPE 


II 


therefore,  is  practically  that  which  the  experience  of  manufac- 
turers has  found  to  be  necessary,  and  in  all  factories,  that  thickness 
is  nearly,  though  not  entirely,  uniform  for  the  different  sizes  of 
pipe.  In  the  early  days  of  the  use  of  sewer  pipe  when  little  was 
known  either  of  the  strength  or  durability  of  the  material,  many 
failures  resulted  from  the  injudicious  haste  with  which  pipes  were 
used  in  large  quantities  without  any  tests  being  made  as  to  their 
ability  to  withstand  the  strains  to  which  they  were  to  be  subjected. 
As  a  rule,  all  the  early  pipes  were  made  too  thin  to  stand  the 
weight  of  the  superincumbent  earth  in  deep  cuttings,  even  had 
they  been  of  the  good  quality  of  the  modern  pipe.  In  Croyden,1 
England,  for  example,  where  sewer  pipes  were  first  used,  1 5-inch 
pipes  were  laid  in  a  trench  20  feet  deep,  and  as  the  pipes  were 
what  we  should  call  bad,  and  were  only  five-eighths  inch  thick, 
it  is  not  surprising  that  the  pipe  line  collapsed,  and  that  a  brick 
arch  had  to  be  built  over  the  top.  The  thickness  has  been 
increased  since  that  time,  however,  and  at  present  the  average 
thickness  of  standard  pipe  is  as  given  in  the  following  table.2 
Manufacturers  also  make  a  thicker  pipe  in  the  larger  sizes, 
intended  to  be  used  under  railroads,  near  street  surfaces,  and  in 
very  deep  cuttings.  The  thickness  of  this  "  double-strength 
pipe"  is  also  given,  its  value  being  discussed  later  under  the  head 
of  strength  of  pipe. 


Size  of  pipe  

6 

8 

o 

IO 

12 

I  C 

18 

2O 

24 

T.O 

36 

Standard 

I 

4 

« 

1 

Tj 

T4 

I  | 

if 

>ft 

7* 

Double  strength 

T* 

T} 

T* 

l| 

2 

2\ 

?f 

The  joint  is  the  weakest  part  of  a  sewer  pipe  line,  because  of  its 
lack  of  rigidity,  and  from  its  failure  to  be  water-tight.  In  1891, 
there  were  inaugurated  by  the  Portland  Stoneware  Company  (in 
1895  adopted  by  the  Eastern  Association  of  Pipe  Manufacturers) 
changes  in  the  dimensions  of  the  sockets,  in  which  two  classes  were 
recognized,  Standard  and  Deep-and-wide  sockets.  The  following 

1  Latham's  Sanitary  Engineering,  p.  187. 

2  Catalogue  of  American  Sewer  Pipe  Company. 


12 


SEWER   CONSTRUCTION 


table  gives  the  depth  of  socket  and  the  thickness  of  joint  for  the 
two  classes,  the  relative  appearance  being  shown  in  Fig.  6. 


Size  of  pipe 

6 

8 

IO 

I  2 

T  C 

18 

20 

24. 

Depth  Standard  joints 

i  ^ 

2 

2 

oi 

"i 

I* 

2  J 

7* 

Thickness    "           " 

:J 

i 

a 

3 

* 

I 

i 

->  . 

"$ 

->| 

"§ 

•7 

•J 

3i 

31 

2 

/I 

Thickness         "                  " 

i 

I 

f 

'f 

'f 

1 

4f 

Experiments  have  been  made  on  the  relative  value  of  the  two 
kinds  of  sockets,  and  while  it  has  been  found  in  laboratory  exper- 
iments that  on  account  of  the  porosity  of  the  cement  filler,  a  well- 
made  joint  in  a  wide  socket  allows  a  greater  leakage  than  in  a 


Deep   and  wide 


Standard 


Fig.  6 


standard  socket,  yet  practically  the  increased  space  for  the  joint 
filler  makes  imperfect  joints  less  likely,  and  really  makes  a  tighter 
line.  The  deep-and-wide  sockets  should,  therefore,  always  be 
used  wherever  the  sewer  is  laid  below  ground  water,  and  where 
consequently  there  is  danger  of  leakage  into  the  pipe. 

Another  recent  improvement  in  the  socket  is  the  introduction 
of  corrugations  on  the  inside  of  the  bell  and  on  the  outside  of  the 
spigot,  by  which  the  cement  is  held  firmly  and  cannot  be  driven 
out  by  settlement  or  pressure.  These  corrugations  are  not  added 
by  all  firms,  but  they  are  easily  scratched  on  the  pipe  and  should 
always  be  called  for  in  specifications. 


CHAPTER   II. 


SEWER  PIPE,  Continued. 

UP  to  the  year  1890,  no  comprehensive  experiments  on  the 
strength  of  pipe  had  been  carried  out,  and  no  systematic  attempts 
to  discover  under  what  conditions  sewer  pipe  could  be  safely 
trusted  to  carry  its  given  load  had  been  made.  The  few  tests 
recorded  before  that  time  are  isolated  experiments  by  engineers 
made  in  the  course  of  their  regular  work.  In  1859,  Mr.  Adams, 
City  Engineer  of  Brooklyn,  made  some  crushing  tests  of  the 
material  used  in  pipes.1  He  prepared  some  two-inch  cubes,  and 
obtained  a  pressure  of  50,000  pounds,  the  capacity  of  the  machine, 
or  12,500  pounds  per  square  inch,  without  crushing  the  material. 
He  also  applied  pressure  along  the  top  of  some  domestic  and 
imported  pipes,  and  found  that  they  broke  as  follows : 


Length. 

Diameter. 

Pounds. 

Pounds  per 
Linear  Foot. 

Scotch  pipe  

Feet. 

7 

Inches. 
18 

5542 

1847 

Scotch  pipe 

? 

12 

4000 

1333 

English  pipe 

•} 

12 

4600 

1533 

English  pipe              .    ... 

2 

12 

1672 

836 

In  1878,  Mr.  J.  Herbert  Shedd,2  City  Engineer  of  Providence, 
made  some  tests  on  the  strength  of  standard  sewer  pipes,  half- 
bedded  in  sand,  with  the  following  results  in  pounds  per  linear 
foot  of  pipe. 


No.  of  Kinds. 

Minimum. 

Maximum. 

Average. 

12-inch  pipes 

4 

14^6 

1765 

1601 

i5-inch  pipes  
1  8-inch  pipes               .  .  . 

4 
•? 

1261 
1464 

I765 
1942 

1452 
1670 

1  Sewers  and  Drains  for  Populous  Districts,  p.  92. 

2  Sewers  and  Drains  for  Populous  Districts,  p.  93. 

13 


14  SEWER  CONSTRUCTION 

In  1890,  Mr.  Malverd  A.  Howe,1  of  the  Rose  Polytechnic  Insti- 
tute, undertook  to  make  systematic  tests  that  would  be  compre- 
hensive, so  far  as  American  pipes  were  concerned,  and  for  this 
purpose  he  obtained  in  the  open  market  specimens  of  pipe  from 
the  different  factories  between  Wilmington,  Del.,  and  St.  Louis, 
Mo.,  fifteen  different  firms  being  represented.  The  pipes  were 
subjected  to  five  different  kinds  of  tests,  viz.,  hydrostatic,  drop, 
concentrated  load,  uniform  load,  and  joints. 

The  hydrostatic  tests  were  made  to  find  out  the  strength  of  the 
pipe  against  internal  pressure,  the  ends  of  single  lengths  of  pipe 
being  closed  and  water  pumped  in  until  the  pipe  broke.  The 
average  tensile  strength  of  the  material  for  the  different  sizes  was 
as  follows : 


4  inches 517  Ibs. 

6  inches 678  Ibs. 

8  inches 552  Ibs. 

10  inches 702  Ibs. 


12  inches 592  Ibs. 

18  inches 529  Ibs. 

21  inches 617  Ibs. 

24  inches 856  Ibs. 


The  number  of  specimens  tested  for  all  sizes  up  to  1 8  inches  was 
25,  and  but  two  above  18  inches.  From  these  results  the  experi- 
menter concluded  that  the  average  tensile  strength  of  the  material 
composing  American  vitrified  sewer  pipe  was  at  least  600  pounds 
per  square  inch. 

Most  of  the  pipes  broke  at  an  internal  pressure  of  about  100 
pounds  per  square  inch,  and  the  following  table  shows  the  com- 
puted thickness  of  the  various  sizes,  assuming  an  internal  pressure 
of  100  pounds  per  square  inch,  with  a  tensile  strength  of  the 
material  of  600  pounds,  as  compared  with  the  thicknesses  now 
made  commercially. 


Size 

6 

8 

10 

12 

18 

21 

24 

Theoretical  thickness    
^Manufactured       " 

•5° 
76 

.66 

82 

.83 
no 

I  .00 
I  .OS 

i-5° 
i  .39 

i-75 
J  .89 

2  .OO 
2  .02 

The  table  shows  that  the  thickness  of  sewer  pipe  is  such  that 
pipes  will  stand  an  internal  pressure  of  100  pounds  and  even  more 

1  Jo.  Assn.  Eng.  So< -.,  Vol.  10,  p.  284. 


SEWER  PIPE  15 

with  the  smaller  sizes  before  bursting,  or  a  safe  pressure  of  33 
pounds  with  a  factor  of  safety  of  three. 

The  drop  test  was  made  to  determine  the  resistance  of  the  pipe 
to  percussive  action,  such  as  a  blow  from  a  wagon  wheel.  It  was 
made  by  supporting  the  pipe  on  two  pieces  of  wood  2  inches  wide, 
1 6  inches  apart,  so  arranged  that  a  falling  weight  would  strike  the 
pipe  near  its  center,  midway  between  the  supports.  The  weight 
was  a  box  full  of  iron,  weighing  18  pounds.  A  rounded  strip  of 
wood  on  the  bottom  was  the  striking  part.  The  length  of  the  drop 
was  adjustable,  but  was  12  inches  for  the  first  five  blows.  If  the 
pipe  was  not  then  broken,  the  length  of  drop  was  made  18  inches, 
then  24  inches,  with  30  inches  as  a  maximum.  Twenty  lengths 
were  broken  at  the  first  blow,  and  most  of  the  pipes  were  broken 
in  four  to  ten  blows.  Mr.  Howe's  conclusion  was  that  sewer  pipe 
as  made  is  strong  enough  to  sustain  ordinary  blows,  but  it  is 
evident  that  where  successive  blows  may  be  expected,  ample 
covering  of  earth  or  similar  material  should  be  provided  to  dis- 
tribute the  shock. 

The  concentrated  load  test  was  made  by  supporting  the  pipe, 
as  just  described,  and  then  slowly  applying  the  load  through  the 
medium  of  an  hydraulic  piston,  acting  against  a  small  block  of 
wood  at  the  middle  of  the  top  of  the  pipe.  Forty-two  pipes  of 
various  sizes  were  broken,  and  while  the  smaller  sizes  withstood 
much  more  than  2000  pounds,  it  seemed  a  safe  conclusion  that 
the  average  pipe  would  stand  at  least  that  amount  concentrated 
at  the  center  with  the  supports  16  inches  apart. 

The  uniform  load  test  was  made  by  bedding  the  pipe  in  sand 
in  a  strong  box  and  applying  pressure  through  a  sand  cover. 
Most  of  the  pipe  failed  by  splitting  longitudinally  at  the  top,  bot- 
tom, and  sides,  and  after  splitting  and  taking  their  new  bearings, 
were  able  to  carry  much  heavier  loads.  The  breaking  loads, 
however,  were  taken  when  the  pipe  cracked.  The  small  sizes 
sustained  a  load  of  about  8000  pounds  per  linear  foot  of  pipe,  and 
the  larger  sizes  a  little  over  2000  pounds,  the  conclusion  being 
that  all  sizes  of  pipe  will  stand  a  load  of  2000  pounds  per  linear 
foot  before  breaking. 


16 


SEWER  CONSTRUCTION 


In  1897,  Mr.  Barbour,  then  City  Engineer  of  Brockton,  Mass., 
made  some  experiments1  on  the  strength  of  pipe  by  covering  it 
with  about  a  foot  of  earth  and  applying  the  pressures  by  means  of 
an  hydraulic  piston  pressing  down  upon  the  earth  cover.  He 
found  that  the  breaking  load  per  linear  foot  averaged  about 
2800  pounds  for  standard  pipe,  and  about  4200  pounds  for 
double  strength  pipe.  He  also  studied  the  relation  between  the 
strength  and  thickness  and  concluded  that  the  strength  varied 
inversely  as  the  diameter  and  directly  as  a  function  of  the  thick- 
ness, the  relation  being  approximately  expressed  by  the  equation 

A.  65 

P  =  C—j- ,  where  P  is  the  pressure  in  pounds  per  linear  foot, 

/  is  the  thickness  in  inches,  and  C  a  constant  equal  to  33,000. 
The  table  shows  the  relation  obtained  experimentally  and  by 
the  formula,  and  their  close  agreement. 


Single  Strength,  or  Standard. 


Size. 

Thickness. 

Strength 
by  Exper- 
iment. 

Strength 
by 
Formula. 

Thickness. 

Strength 
by  Exper- 
iment. 

Strength 
by 
Formula. 

Inches. 
6 

6oc 

Inches. 

8 

•"95 
822 

2QO2 

oUJO 
208? 

JO 

832 

•*vw^ 

2834 

2440 

12 
IS 

18 

20 
24 

.024 
.18 
.29 
•3°5 
•47 

3226 
3207 
268l 
2584 
2549 

2862 
2890 
2790 
2560 
2598 

1.26 
I  .405 
i-54 
i-74 

2  .02 

3916 
4562 
4146 
4119 
4334 

4028 
3855 
3738 
4113 
4382 

Double  Strength. 


Mr.  Barbour  concludes  from  his  experiments  that  manufac- 
turers should  be  able  to  produce,  and  that  engineers  should 
demand,  pipe  which  would  have  a  breaking  load  of  3000  pounds 
per  linear  foot  for  standard  pipe,  and  of  4500  pounds  for  double 
strength  pipe,  the  thickness  being  so  varied  according  to  his 
formula  or  otherwise,  that  this  strength  should  be  obtained  in  all 
sizes.  The  thickness  thus  required  is  given  below  and  may  be 
compared  with  the  thicknesses  given  in  the  table  on  page  1 1 : 

1  Jo.  Assn.  Eng.  Soc.,  Vol.  19,  p.  193. 


SEWER  PIPE 


BARBOUR'S  TABLES. 


Size. 

Thickness 
for  3000 
Pounds. 

Thickness 
for   4500 
Pounds. 

Size. 

Thickness 
or  3000 
Pounds. 

Thickness 
for   4500 
Pounds. 

6 

o  7 

0  8n 

I  f 

I    21 

I    £4 

8   .... 

0.82 

I  .06 

I     3^ 

1  o^- 

I    72 

10   

O    Q4 

I  .21 

20    

I    44 

I    84 

12  

1.  06 

1-36 

24  

1.  60 

2.08 

The  average  breaking  load  for  sewer  pipe  is  unfortunately  not 
a  fair  criterion  for  the  strength  of  the  individual  pipe.  It  is  cus- 
tomary to  test  pipes  roughly  by  striking  them  with  a  hammer  in 
order  to  detect  by  the  sound  cracked  and  underburned  pipes; 
whereupon  such  defective  pieces  are  thrown  out.  But  even  with 
such  pipes  eliminated,  those  which  are  apparently  perfectly  sound 
show  great  differences  in  strength.  For  example,  in  the  case  of  the 
1 80  pipes  tested  by  Mr.  Barbour,  in  each  size  the  best  pipe  with- 
stood a  load  nearly  double  that  withstood  by  the  poorest,  the 
24-inch  pipe  varying  from  1482  pounds  to  3280  pounds  per  linear 
foot. 

In  Providence,  in  1894,  the  City  Engineer1  tested  some  pipe  as 
follows : 

8-inch,  minimum  load  per  foot  757,  maximum  2498  pounds. 
12-inch,  minimum  load  per  foot  924,  maximum  2816  pounds. 
15-inch,  minimum  load  per  foot  1063,  maximum  2666  pounds. 
i8-inch,  minimum  load  per  foot  1305,  maximum  2401  pounds. 

This  shows  a  great  difference  in  the  possible  loading,  and  it  also 
shows  the  danger  of  pipes  breaking,  if  loaded,  even  approximately, 
to  what  an  average  pipe  would  bear. 

Mr.  Barbour  thinks  that  the  average  pipe  will  stand  about 
2800  pounds,  although  from  his  own  experiments  this  amount  is 
twice  that  which  the  poorest  pipe  actually  withstood  and  35  per 
cent  more  than  the  average  of  the  poorest  pipes  of  the  15  different 
groups  tested. 

The  tests,  moreover,  are  made  on  pipes  carefully  bedded  or 
supported.  In  a  trench,  there  is  continual  danger  of  the  pipes  not 

1  See  Report  of  City  Engineer,  p.  41. 


1 8  SEWER  CONSTRUCTION 

being  supported  carefully,  of  the  dirt  not  being  well  tamped  back 
under  the  pipes,  of  the  sheeting  being  withdrawn  on  one  side,  and 
not  on  the  other,  etc.  This  makes  the  danger  from  broken  pipes 
still  greater,  and  it  is  a  matter  of  experience  that  such  imperfec- 
tions do  frequently  develop  under  actual  conditions. 

For  example,  Mr.  Rust,  City  Engineer  of  Toronto,  said  in 
I888,1 

We  had  occasion  to  take  up  a  short  time  ago  a  piece  of  i8-inch  drain  laid 
with  Scotch  pipe  in  a  newly  annexed  territory,  when  it  was  found  that  about  75 
per  cent  of  the  pipe  were  cracked,  a  large  majority  being  broken  on  bottom,  top, 
and  sides. 

Mr.  Keating,2  in  the  city  of  Halifax,  says  that  it  is  an  unusual 
thing  to  find  a  pipe  sewer  over  12  inches  in  diameter  in  a  perfect 
state.  He  cites  a  case  in  Halifax,  about  1884,  where  a  long  line 
of  15-inch  pipe  collapsed  entirely  a  few  months  after  being  laid, 
due  to  the  back-filling  being  frozen  and,  therefore,  imperfectly 
tamped  in  under  the  pipe. 

Mr.  J.  H.  Parker,3  discussing  failures  of  pipe  in  trench,  com- 
ments on  the  frequency  of  such  occurrences,  and  shows  that  much 
of  the  trouble  is  due  to  the  method  of  draining  the  trench  during 
construction,  the  pumps  and  drains  withdrawing  sand  and  earth 
from  around  the  pipe  for  a  distance,  in  some  cases,  of  as  much 
as  ten  feet.  The  subsequent  settlement  of  the  pipe  results  in 
fracture. 

Mr.  Hastings,4  City  Engineer  of  Cambridge,  Mass.,  has  had 
the  same  experience  of  frequent  instances  of  broken  pipe,  and 
concludes  that  in  soils  or  under  construction  methods  where 
standard  pipe  would  fail,  double  strength  would  also  fail.  He 
recommends,  therefore,  that  where  the  soil  is  uneven  and  uncer- 
tain, the  sewer  pipe  be  surrounded  or  reinforced  with  brick  or 
concrete.  He  cites  instances  where  lo-inch  and  1 2-inch  pipe  in  a 
7-foot  trench  have  been  crushed  by  the  passage  of  a  steam  roller 
on  the  surface  of  the  street  above. 

1  Trans.  Can.  Soc.  C.  E.,  Vol.  2,  p.  306. 

2  Trans.  Can.  Soc.  C.  E.,  Vol.  i,  p.  517. 
8  W.  Soc.  Engineers,  Vol.  i,  p.  517. 

4  Assn.  Eng.  Soc.,  Vol.  22,  p.  87. 


SEWER  PIPE  19 

At  Oberlin,  Ohio,1  where  the  sewer  after  completion  was  tested 
by  passing  a  wooden  ball  through  the  pipes,  1300  linear  feet  were 
found  broken  out  of  a  total  length  of  8650  feet  of  1 8-inch  sewer, 
continuous  breaks  occurring  from  25  to  500  feet  each.  The  pipe 
was  good  pipe,  carefully  laid,  with  bell-holes,  but  with  untamped 
trenches.  In  relaying,  shale  pipe  was  used  with  careful  tamping. 
In  a  month,  150  feet  of  this  was  broken. 

In  the  construction  of  the  joint  trunk  sewer  in  New  Jersey,  Mr. 
Alexander  Potter  was  able  to  investigate  this  question  with  the 
following  results:2 

On  26,303  feet  of  24-inch  pipe,  breaks  occurred  aggregating  1500  feet,  each 
break  running  from  15  to  150  feet,  nearly  all  of  them  being  either  in  gravel 
or  rock  cuttings.  No  breaks  were  found  in  quicksand.  The  depths  of  cuts  where 
breaks  occurred  varied  from  6  to  20  feet,  but  more  broken  pipes  were  found  at 
the  lesser  depths. 

On  8197  feet  °f  22-inch  standard  pipe,  at  depths  varying  from  6  to  20  feet, 
much  of  which  was  laid  on  timber  foundation,  and  none  on  gravel  or  broken  stone, 
not  a  single  cracked  pipe  was  found. 

Fourteen  breaks  occurred  on  4382  feet  of  2o-inch  pipe,  aggregating  500  feet 
in  all.  All  of  these  breaks  occurred  in  rock  cuttings  where  the  pipe  was  tempo- 
rarily supported  on  blocks  until  selected  material  was  rammed  solidly  around  and 
under  the  pipe.  A  close  inspection  of  the  uncovering  of  the  pipe  revealed  the  fact 
that  at  certain  places  sufficient  spaces  had  not  been  left  at  the  springing  line  of 
the  pipe  to  allow  room  for  the  proper  ramming  of  the  back-filling  around  the 
lower  half  of  the  pipe. 

On  the  short  stretch  of  1 8-inch  pipe,  laid  on  a  heavy  grade,  the  sewer  col- 
lapsed shortly  after  construction,  due  to  the  flood  of  water  washing  out  the  newly 
filled-in  material  over  the  sewer  under  the  macadam  pavement  which  dropped 
on  the  pipe  and  ruptured  it. 

Mr.  Potter's  conclusion  is  that 

the  larger  sizes  of  vitrified  pipe  should  not  be  used  in  sanitary  sewer  construc- 
tion, say  on  2O-inch  and  over,  except  on  a  concrete  base,  and  the  relative  cost  of 
other  material  should  be  compared  upon  this  assumption.  On  sizes  smaller  than 
20-inch,  concrete  should  be  used  under  the  vitrified  pipe  far  more  generally  than 
it  is  at  present. 

The  author,  however,  in  1894,  laid  about  3000  feet  of  24-inch 
double  strength  pipe  in  a  trench  8  to  16  feet  deep,  and  so  far  as 

1  Eng.  News,  Vol.  31,  p.  205. 

2  Spec.  Rept.  on  Joint  Trunk  Sewer  System  in  Valleys  of  Rahway  and  Eliza- 
beth Rivers. 


20  SEWER  CONSTRUCTION 

he  can  ascertain  by  the  records  of  house  connections,  none  of  the 
pipe  has  been  broken. 

The  weight  of  superincumbent  earth  on  a  24-inch  pipe,  assum- 
ing (which  is  doubtful)  that  the  full  weight  of  the  earth  presses 
on  the  pipe,  would  be,  for  a  2O-foot  trench,  2  X  20  X  100,  or  4000 
pounds,  the  weight  of  a  cubic  foot  of  earth  being  taken  at  100 
pounds.  From  references  given  on  page  17  the  strength  of  24- 
inch  standard  pipe  may  be  as  low  as  1482  pounds,  so  that  break- 
age under  such  conditions  is  not  surprising.  Mr.  Barbour  thinks 
from  his  experiments  that  in  trenches  over  10  feet  deep,  the 
pressure  of  the  earth  on  the  pipes  is  a  definite  ratio  of  the  weight 
of  the  superincumbent  earth,  the  ratio  being  the  difference 
between  the  coefficient  of  friction  for  that  earth  and  unity. 
This  implies  a  ratio  running  from  35  per  cent  for  sand  to  65 
per  cent  for  clay.  But  even  with  this  assumption,  the  pressure 
of  the  earth  on  the  pipe  for  clay  filling  would  be  more  than  the 
strength  of  the  pipe  could  stand,  and  a  failure  might  be  reason- 
ably expected. 

The  usual  method  of  making  cement  joints  in  sewer  pipe  is 
to  fill  the  space  between  the  bell  and  spigot  with  cement, 
sometimes  introducing  first  a  strand  of  oakum  into  the  bottom 
of  the  joint.  That  this  may  give  a  tight  joint  is  proved  by 
the  fact  that  .cement  joints  are  frequently  used  for  gas  pipes 
without  appreciable  leakage.  Laboratory  tests  where  the  joint 
between  the  two  sewer  pipes  is  made  in  full  view,  well  com- 
pacted, and  given  two  weeks  or  more  to  harden,  show  that 
such  a  joint  allows  but  a  negligible  amount  of  leakage.  But 
the  fact  that  the  number  of  joints  in  a  sewer  line  is  large,  that 
sewers  are  laid  in  deep  trenches,  frequently  bedded  in  mud  or 
quicksand,  between  sheeting  boards  where  room  is  limited,  causes 
cement  joints  in  sewer  pipes  to  be  generally  unsatisfactory.  Mr. 
Howe,1  in  his  series  of  tests  made  a  number  of  cement  joints, 
under  the  most  favorable  conditions,  with  all  parts  of  the  joint 
equally  visible  and  accessible,  and  yet  with  all  possible  care  used, 
with  the  joints  hardened  from  one  to  six  weeks,  and  with 
practically  no  leakage  with  the  pipe  barely  full  of  water,  some 

1  Loc.  cit. 


SEWER  PIPE 


21 


of  the  joints  would  allow  no  pressure  at  all,  and  the  best  of 
them  failed  utterly  under  a  pressure  of  15  pounds  per  square  inch. 
The  fact  that  when  the  pipes  concerned  in  the  joint  were  held 
together  by  iron  rods  to  prevent  axial  motion,  they  withstood  much 
higher  pressures,  shows  that  the  failure  is  due  probably  to  the 
water  under  pressure  getting  behind  the  end  of  the  spigot.  The 
laboratory  tests  that  have  been  made  indicate  that  even  with 
every  precaution  taken,  and  solely  on  account  of  the  porosity  of 
the  cement,  a  leakage  of  about  5000  gallons  per  mile  per  day 
for  6-inch  pipe  must  be  expected  as  a  minimum,  this  amount 
increasing  approximately  as  the  square  of  the  diameter  for  other 
sizes.  Under  actual  conditions,  however,  this  amount  may 
very  easily  increase  four  or  five  times.  A  proper  care  in  making 
cement  joints  in  sewer  lines  would  undoubtedly  diminish  the 
leakage  through  them,  such  care  being  expended  on  having  the 
cement  mixed  to  just  the  right  consistency,  so  that  it  may  be 
rammed,  on  having  the  cement  thoroughly  rammed  into  the 
joint  completely  around  the  pipe,  on  having  the  trench  kept  free 
from  water  until  the  cement  has  set,  and  on  having  the  joints 
undisturbed  by  careless  workmen  until  the  cement  has  thoroughly 
hardened.  It  is  an  advantage  to  have  two  or  three  pipes  jointed 
on  the  bank,  especially  in  the  case  of  6-inch  or  8-inch  pipe  to  be 
laid  below  ground  water  level,  the  joints  made  out  of  the  trench 


Fig.  7 

being  better  than  those  made  in.     Fig.  7  1  shows  a  form  of  sup- 
port suggested  by  Mr.  Coffin,  as  suitable  for  this  purpose,  and 

1  Assn.  Eng.  Soc.,  Vol.  13,  p.  712. 


22  SEWER  CONSTRUCTION 

Fig.  81  shows  an  auxiliary  device    for  holding    the  lengths  of 
pipe,  so  joined,  rigid  while  they  are  lowered  into  the  trench. 

Improvements  in  joints  as  they  have  been  suggested  or  actually 
put  to  test,  divide  themselves  naturally  into  two  classes,  viz.,  first, 
those  where  the  ordinary  bell  and  spigot  pipe  is  used,  but  where, 


Fig.  8 


instead  of  cement,  some  other  jointing  material  is  substituted;  and 
second,  where,  instead  of  the  ordinary  form  of  pipe,  a  modified 
form  of  bell  or  spigot,  or  both,  is  used. 

In  the  first  class  several  substitutes  for  cement  have  been  tried, 
among  which  sulphur  and  sand,  with  or  without  tar  in  addition, 
is  the  most  common.  With  tar,  the  proportion  being  about  one 
part  of  tar,  four  parts  of  sulphur,  and  six  parts  of  sand,  the  mix- 
ture is  that  used  in  the  so-called  Stanford  joint,  popular  for  many 
years  in  England.  The  late  Colonel  Waring  used  it  in  Stamford, 
Conn.,  and  in  Norfolk,  Va.,2  though  with  doubtful  success.  Mr. 
Mohun,  Chief  Engineer  of  the  Sewerage  Works  of  Victoria,  B.C., 
however,  was  well  satisfied  with  its  use  in  that  city.3  To  prepare 
the  mixture,  which  is  molded  on  to  the  pipe  so  that  a  water-tight 
slip  joint  is  obtained,  the  sulphur  and  sand  are  heated  separately 
in  kettles,  then  mixed  and  the  tar  added,  and  while  still  hot  the 
mixture  is  poured  into  the  molds  which  form  the  castings.  The 
castings  are  made  with  the  pipe  vertical,  exposing  it  on  all  sides 
for  inspection.  The  composition  cools  in  a  few  moments,  and 
the  molds,  shown  in  Fig.  9,  are  ready  to  be  used  with  another 
pipe.  The  pipes,  thus  molded,  are  laid  by  coating  the  joint  with 
some  heavy  oil  or  grease  and  simply  shoving  the  pipes  together. 
The  defect  of  this  joint  as  first  made  was  that  the  surfaces  in  con- 
tact were  conical,  so  that  no  movement  of  the  pipe  was  possible 

1  Eng.  News,  Vol.  33,  p.  122.  2  Waring's  Sewerage,  pp.  104,  153. 

8  Trans.  Can.  Soc.  C.  E.,  Vol.  10,  p.  84. 


SEWER  PIPE 


without  destroying  the  joint  or  breaking  the  pipe.     An  English 
firm,  Doulton   &  Co.,1  casts  the  material  so  as  to  make  a  ball 


Wooden 
/  Lifting  Bar 


Enlarged  view  of 
joint 


Moulds  m  place 


MALE  MOULD 


~~R~~      ~^--~~      ~~--— --o 

Q    ~- ^a*  *T    ~"~ 

-— -   f»  <> 


I     ' 


Details  of  cast  iron  moulds 

Fig.  9 


and  socket  joint,  allowing  a  small  deflection,  an  improvement 
much  appreciated  by  English  engineers.  The  author  has  made 
and  tested  the  ordinary  form  of  these  joints,  and  believes  that  if 

1  Doulton's  Catalogue. 


SEWER   CONSTRUCTION 


the  space  between  the  bell  and  spigot  could  be  increased,  the 
joints  would  be  very  serviceable,  but  with  the  present  dimensions 
of  American  pipe  there  is  not  space  enough  to  give  a  proper 
thickness  to  the  casting. 

Mr.  Potter,1  for  pipes  in  wet  ground  in  connection  with  the 
joint  trunk  sewer  of  New  Jersey,  omitted  the  tar,  and  used  only 
the  sulphur  and  sand  mixture,  pouring  it  as  a  lead  joint  in  iron 
pipe  would  be  poured.  He  claims  in  this  way  to  be  able  to  get  a 
practically  water-tight  joint  at  a  cost  but  little  above  that  of  the 
ordinary  cement  joint.  He  used  from  35  to  45  per  cent  of  sand. 
The  larger  portion  of  this  sand  was  used  when  the  temperature 
of  the  air  was  above  35°  F.  His  experience  indicates  that  even 
in  winter,  when  the  rapid  cooling  makes  fine  hair  cracks  appear, 
the  composition  is  practically  water-tight,  provided  the  mixture 
fills  the  joint  space  completely.  The  finer  the  sand,  the  better  the 
results  obtained,  and  it  is  possible  to  buy  the  sulphur  and  sand, 
of  the  proper  fineness,  all  mixed,  from  the  sulphur  manufacturers. 
The  cost  of  the  mixture  was  $40  per  ton,  and  the  cost  of  the 
joint  for  the  8-inch  pipe  was  2.5  cents.  The  experience  of  the 
author  indicates  that  it  requires  some  little  practice  to  regulate 
the  temperature  of  the  mixture,  too  low  a  temperature  reducing 
the  fluidity,  and  too  high  a  temperature  causing  the  mixture  to 
become  thick  and  pasty,  so  that  it  will  not  pour.  The  material 
and  corresponding  cost  for  different  sizes  of  pipe  are  given  by 
Mr.  Potter  as  follows: 


Pounds 
of 

Cost  of  Joints. 

Cost  per  Foot. 

Size. 

Mixture 
per 
.  Joint. 

Mixture. 

Gasket. 

Labor. 

Total. 

3  -Foot 
Length. 

a-Foot 
Length. 

24 

10 

•125 

.02 

•13 

•2Q5 

.10 

•IS 

22 

9 

.112 

.02 

•13 

.282 

•095 

•14 

2O 

8 

.10 

.02 

.12 

.260 

.090 

•13 

18 

7 

.087 

.02 

.11 

•247 

.08 

.12 

15 

5-5 

.069 

.01 

.10 

.187 

.065 

•095 

12 

4-2 

.052 

.01 

.09 

.162 

•°55 

.08 

IO 

3-3 

.041 

.01 

.08 

.141 

•045 

.07 

8 

2-5 

.031 

.01 

.07 

.121 

.04 

.06 

1  Special  Report  on  Joint  Trunk  Sewer. 


SEWER  PIPE  25 

Another  mixture  also  used  by  Mr.  Potter  in  this  work  was  a 
combination  of  North  Carolina  pine  tar  and  cement,  mixed  and 
kneaded  until  about  the  consistency  of  putty.1  This  can  be  forced 
into  the  joint  even  under  water  so  as  to  completely  fill  the  joint 
space.  In  laboratory  experiments  of  the  author,  the  material 
has  the  disadvantage  of  hardening  so  slowly  that,  in  a  horizontal 
position  and  especially  on  warm  days,  the  material  settles  slowly 
by  its  own  weight,  leaving  an  open  space  at  the  top  of  the  pipe. 
Mr.  Potter  had  the  same  experience,  the  tendency  to  sag  offset- 
ting, in  his  opinion,  the  advantages  which  the  plasticity  of  the 
material  offered. 

Asphalt  has  been  used  as  a  substitute  for  cement,  the  first  tests 
and  use  probably  being  at  Frankfort-am-Main  about  1896. 
Mr.  H.  W.  Lindley  2  there  used  ordinary  sewer  pipe,  and  a  mix- 
ture of  Trinidad  liquid  asphalt  with  solid  bitumen.  This  was 
poured  hot  into  the  joint  as  in  jointing  iron  pipe.  In  this  country, 
equal  quantities  of  Trinidad  bitumen  and  rock  asphalt  have  been 
used  in  the  same  way.  At  Steelton,  Pa.,3  strips  of  burlap,  4  inches 
wide,  were  soaked  in  hot  asphalt,  twisted,  and  calked  into  the 
joint  like  oakum.  It  was  claimed  that  joints  thus  made,  when 
hard,  stood  an  internal  pressure  of  50  pounds  per  square  inch, 
without  giving  way,  the  time  to  harden  being  about  30  minutes. 
At  Oakland,  Cal.,4  pipes  without  bells  were  used,  and  the  joints 
made  by  wrapping  a  wide  strip  of  burlap  around  the  joint.  The 
burlap  was  soaked  in  hot  asphalt  and  tied  on  to  both  pipes  tightly. 
The  engineer,  Mr.  Miller,  reported  at  the  time  that  he  was  able  to 
get  a  joint  in  this  way  that  would  stand  an  internal  pressure  of 
200  pounds  per  square  inch  —  a  seeming  impossibility. 

Considerable  improvement  in  the  ordinary  cement  joint  may 
be  obtained,  especially  in  wet  ground,  by  wrapping  the  joints 
tightly  with  cloth.  At  Medford,  Mass.,  Mr.  Barnes  used  cheese- 
cloth; 5  in  Ithaca,  N.  Y.,  the  sewer  superintendent  uses  table  oil- 

Loc.  cit. 

Paving,  Vol.  30,  p.  35. 

Eng.  News,  Vol.  41,  p.  405. 

Paving,  Vol.  19,  p.  45,  and  Eng.  Rec.,  Vol.  41,  p.  571. 

Paving,  Vol.  13,  p.  306. 


26  SEWER  CONSTRUCTION 

cloth.  This  latter  material  holds  the  cement  up  to  the  joint  even 
in  water  and  allows  it  to  harden  without  falling  away  from  the 
pipe. 

Since  defective  joints  add  so  largely  to  the  expense  of  a  sewerage 
system  (if  ground  water  is  to  be  kept  out),  requiring  the  use  of 
cast  iron  pipe  or  a  large  expense  in  maintenance  for  handling 
the  extra  water,  it  would  seem  desirable  that  if  a  better  material 
than  cement  is  to  be  had  that  it  should  be  used  to  hold  the  leakage 
down  to  a  minimum.  Instances  are  by  no  means  rare  in  this 
country  of  sewerage  systems  being  practical  failures  through 
the  large  amount  of  ground  water  leaking  into  the  system,  and 
the  importance  of  this  subject  of  joint-making  can  hardly  be  over- 
estimated. 

In  order  to  prevent  leakage,  many  special  forms  of  joints  have 
been  made  in  England,1  and  pipe  manufacturers  regularly  supply 
these  forms  to  the  trade.  The  most  common  of  the  special  forms 
is  the  Stanford  joint  already  referred  to.  The  pipes  may  be  had 
with  the  composition  already  cast  on,  and  either  in  the  conical  or 
spherical  section,  the  latter  being  preferred.  Figs.  10  and  n 
show  the  two  forms  of  section. 

The  Archer  joint  shown  in  Fig.  12  demands  a  special  form  of 
pipe,  requiring  the  bell  end  to  be  changed  into  a  double  groove, 
into  which  the  tongue  of  the  spigot  end  may  fit.  In  making  the 
joint  a  band  of  clay  or  other  material  is  placed  in  the  groove  so 
that  the  tongue,  on  being  driven  home,  is  sealed  at  its  base. 
Then  Portland  cement  grout,  3  cement  to  2  water,  is  poured 
through  the  hole  on  top  so  as  to  fill  the  joint.  The  joint  is 
claimed  to  be  entirely  water-tight. 

The  Hassal  joint  calls  for  no  different  form  of  pipe,  except  per- 
haps a  wider  socket,  but  it  requires  two  composition  rings  to  be 
cast  on  to  the  bell  and  spigot  ends,  exactly  as  if  for  a  double  Stan- 
ford joint.  (See  Fig.  13.)  Between  these  rings  cement  grout  is 
poured  to  fill  the  intervening  space.  These  pipes  were  used 
extensively  in  Southampton,  England,  where  new  works  have 
recently  been  constructed. 

1  See  Moore's  Sanitary  Engineering. 


SEWER  PIPE 


Fig.  10 


Fig.  ii 


Fig.  13 


28  SEWER  CONSTRUCTION 

Other  forms,  which  are  but  variations  of  the  above,  are  on  the 
market,  but  the  principle  is  that  of  one  of  these  two. 

The  Sykes  patent  joint,  shown  in  Fig.  14,  however,  is  a  new 
type,  the  joint  being  due  to  a  screw  thread  formed  in  the  pipe, 


Fig.  14 

a  mixture  like  putty  being  first  put  in  at  the  shoulder  of  the 
thread  so  that  an  effectual  seal  is  obtained.  It  is  stated  that 
this  joint  has  withstood  an  hydraulic  pressure  of  140  pounds  per 
square  inch. 


CHAPTER   III. 
BRICK  SEWERS. 

WHEN  a  sewer  has  a  diameter  greater  than  36  inches,  a  brick 
or  concrete  conduit  must  be  used  instead  of  tile  pipe,  and  it  is 
not  unusual  for  these  materials  to  be  used  in  sizes  as  small  as  24 
inches.  Where  the  soil  is  wet  and  there  is  danger  of  infiltration, 
pipe  should  be  used  up  to  the  largest  size  made.  If  the  ground  is 
dry,  the  cheapest  construction  should  be  followed.  A  further 
advantage,  however,  belongs  to  the  pipe,  viz.,  its  greater  smooth- 
ness, giving  the  pipe  line,  as  compared  with  brick,  a  smaller 
coefficient  of  roughness  or  a  larger  coefficient  of  flow.  Compare, 
for  example,  a  mile  of  36-inch  pipe  with  a  coefficient  of  roughness 
(n,  in  Kutter's  formula)  of  .on,  with  the  same  length  of  brick 
sewer,  whose  coefficient  is  .013.  The  grade  for  the  pipe  to  secure 
a  velocity  of  2.5  feet  per  second  is  i  in  2130,  or  .046  per  cent.  For 
the  brick  sewer  the  required  grade  for  the  same  velocity  is  i  in 
1444,  or  .07  per  cent.  The  brick  sewer  would  therefore  be  1.27 
feet  deeper  in  the  ground  than  the  pipe  sewer  at  the  lower  end, 
an  increase  of  excavation  of  about  600  cubic  yards. 

In  some  localities,  as  in  Nova  Scotia,  where  English  pipe  is 
generally  used,  and  in  the  western  states  of  this  country,  trans- 
portation charges  may  be  so  high  as  to  make  the  use  of  brick  or 
concrete,  even  with  the  larger  amount  of  excavation,  the  cheaper; 
but  in  general,  it  may  be  said  that  economy  will  be  best  served  by 
not  using  brick  until  the  size  required  has  exceeded  that  of  the 
largest  pipe  made. 

Brick  for  sewers  should  be  smooth  and  especially  hard  burned 
—  smooth,  in  order  to  reduce  the  friction  and  to  prevent  the 
arrest  of  floating  particles,  and  hard,  in  order  to  reduce  the  wear- 
ing away  of  the  brick  by  the  attrition  of  the  silt  in  suspension. 
Well-burned  arch  building  brick  are  often  used,  but  paving  brick 

29 


30  SEWER  CONSTRUCTION 

of  the  smaller  sizes  offer  an  admirable  combination  of  all  the 
needed  qualities  except  perhaps  economy.  In  some  localities, 
second-class  pavers  may  be  had  at  a  price  but  little  in  excess  of 

the  cost  of  the  best  building  brick. 
Paving  brick  have  the  advantage  of 
being  impervious  and  non-absorp- 
tive. Since  smoothness  and  tough- 
ness are  essential  only  in  the  bottom 
of  the  sewer,  it  is  common  to  econo- 
mize by  building  only  that  part  of 

paving  brick  or  of  the  best  building 

Fi  r  brick,  using    for   the  backing,  the 

outer  rings,  and  for  the  arch,  ordi- 
nary building  brick.  (See  Fig.  is.)1  The  plastering  is  then 
depended  on  to  prevent  infiltration. 

Where  egg-shaped  brick  sewers  are  built,  the  small  radius  of  the 
invert  requires  the  joints  on  the  outside  to  be  excessively  thick, 
as  shown  in  Fig.  16,  which  has  been  carefully  drawn  to  scale;  and 
to  avoid  this  element  of  constructional  weakness,  invert  blocks 
are  often  used,  as  shown  in  the  same  figure.  These  blocks  are 
made  of  terra  cotta  and  replace  about  four  rows  of  brick.  Fig.  1 7 
shows  the  form  and  dimensions  of  the  standard  blocks  made  by 
the  American  Sewer  Pipe  Company.  These  are  about  a  foot 
long,  have  a  vertical  rib  in  the  center,  a  plane  bottom,  and  the  top 
surface  conforms  in  curvature  to  the  radius  of  the  sewer  in  which 
they  are  to  be  built.  Talbot's  block,  shown  in  Fig.  18,  however,2 
has  the  top  surface  with  a  radius  of  three  inches,  in  order  to 
increase  the  hydraulic  radius  for  small  flows.  The  sides  of  the 
block  are  inclined  at  such  an  angle  that  they  make  the  abutments 
for  the  brick  side  walls.  The  use  of  these  blocks  in  dry  soils  has 
a  distinct  advantage,  the  alignment  being  accurately  preserved,  the 
surface  of  the  blocks  being  smoother  than  that  of  the  bricks,  and 
the  large  blocks  securing  more  rapid  work.  In  wet  soil,  or  in 
unstable  soil,  their  use  is  questionable.  It  is  claimed  that  if  the 

1  Eng.  News,  Vol.  46,  p.  272. 

2  Paving,  Vol.  16,  p.  154. 


BRICK  SEWERS  31 

blocks  are  set  on  planks  that  there  is  no  settlement  and  that  the 
hollows  in  the  blocks  act  as  a  drain  to  carry  off  the  ground  water, 
to  the  great  advantage  of  the  sewer.  But  the  joints  between  suc- 
cessive blocks  are  weak,  and  in  a  large  flow  ground  water  must 
surely  find  its  way  through  the  joints  into  the  sewer.  Latham, 
the  eminent  English  Sanitary  Engineer,  says  that  while  these 
blocks  act  as  drains  during  construction  to  remove  the  subsoil 


Fig.  16 

water,  they  should  be  stopped  up  as  soon  as  possible,  and  may 
well  be  filled  with  concrete  their  entire  length,  the  reason  being 
that  particles  of  earth  are  washed  from  around  each  joint  into  the 
drain,  and  a  settlement  fatal  to  the  integrity  of  the  sewer  follows.. 


SEWER   CONSTRUCTION 


Fig.  17 


Fig.  18 


BRICK  SEWERS 


33 


He  gives  as  his  preference  a  form  of  invert  block,  shown  in  Fig.  19,* 
the  block  being  solid,  with  grooves  on  sides  and  ends. 

The  block  is  so  laid  as  to  break  joints,  the  jointing  cement 
entering  the  groove  on  all  sides,  thus  effectually  tying  the  whole 
together.  In  view  of  Latham's  experience  and  statement,  it  would 


Fig.  19 

seem  that  the  hollow  blocks  should  not  be  used  for  drainage; 
instead,  if  subsoil  drainage  is  necessary,  it  should  be  obtained 
through  a  special  pipe  laid  below  the  sewer  grade. 

An  attempt  is  made  in  the  invention  of  the  Babcock  Hollow- 
Invert  Block  to  remove  the  difficulties  inherent  to  the  use  of 
hollow  blocks  for  drainage,  by  providing  a  special  means  for  the 


Fig.  20 

admission  of  ground  water.  Fig.  20  shows  the  construction  of 
the  blocks.2  It  is  claimed  for  these  blocks  that  on  account  of 
the  circuitous  way  by  which  the  ground  water  gets  into  the  blocks 
that  no  soil  washings  will  occur,  and  further  that  the  joints  between 

1  Latham's  Sanitary  Engineering,  p.  221. 

2  Redrawn  from  catalogue. 


34 


SEWER  CONSTRUCTION 


the  separate  blocks  are  so  designed  that  there  will  be  no  leakage 
from  the  blocks  up  into  the  sewer  itself.  This  seems  to  the  author 
doubtful,  and  he  would  prefer  in  all  cases  to  use  separate  drain  pipes. 
Brick  sewers  possess  the  advantage  over  pipe  sewers  that  their 
cross-section  can  be  varied  to  suit  special  and  local  conditions,  as 
well  as  to  secure  more  uniform  flow  with  varying  depths  of  flow. 
For  the  latter  purpose  egg-shaped  sewers  are  used,  their  advantage 
having  been  pointed  out  in  Chapter  XVI  of  "  Sewer  Design."  1 
The  number  of  bricks  used  in  egg-shaped  sewers  is  slightly  in  excess 
of  circular  sewers  of  the  same  capacity,  and  the  following  tables 
give  data  as  to  the  comparative  dimensions  of  sewers  of  the  same 
capacity,  and  the  number  of  brick  necessary  for  different  sizes. 

QUANTITY    OF    BRICKWORK    FOR    CIRCULAR    SEWERS. 
From  Wollheim's  "Sewerage  Engineer's  Notebook." 


Diameter. 

Cubic  Yards  of  Brickwork  per  Lineal  Foot. 

Ft.      In. 

4}  In.  Thick. 

9  In.  Thick. 

13^  In.  Thick. 

1  8  In.  Thick. 

2       O 

IO7. 

240 

7 

A    O 

.260 

6 

.  12?. 

.28? 

Q 

A     «5 
.  I  37 

o 

V 

3     o 

•  l  j  I 

•  147 

,  7,27 

o 

7 

•    x  T-  / 

•  o*  i 

•  347 

o 
6 

.    I7O 

'  OT'  / 

*    A  /  w 
.l80 

'  3O3 

40 

AT. 

670 

w 

.  2OO 

A.-11 

•  **/** 

6 

2J7 

460 

777 

9 

4s) 

.223 

.  <^.  w 
.480 

•  I  o  I 
.770 

5     o 

•233 

.500 

.800 

3 

•243 

.520 

.830 

6 

.256 

•543 

.867 

.266 

n<"v*i 

6     o 

.277 

•59° 

•  930 

•31 

3 

.287 

.613 

.970 

•36 

6 

.300 

•633 

.00 

.40 

9 

.310 

•653 

.03 

-44 

7     o 

.320 

•673 

.06 

.48 

3 

•33° 

.700 

.  IO 

•53 

6 

•343 

.720 

•  X3 

•57 

9 

•353 

.740 

.  16 

.61 

8     o 

•363 

.760 

.19 

•65 

3 

.376 

.786 

•23 

.70 

6 

•387 

.807 

.26 

•75 

9 

•397 

.827 

.29 

•79 

9     o 

.407 

.850 

•32 

•83 

3 

.420 

•873 

•36 

.88 

6 

•  430 

•893 

•39 

.92 

9 

.440 

•913 

.42 

.96 

10       0 

•453 

•937 

.46 

2.01 

1  Ogden's  Sewer  Design,  p.  192. 


BRICK  SEWERS 


35 


QUANTITY    OF    BRICKWORK    FOR    EGG-SHAPED    SEWERS. 
From  Wollheim's  "  Sewerage  Engineer's  Notebook." 


Dimensions 
Ft.  In.  Ft.  In 

Area 
in 
Square 
Feet. 

Cubic  Yards  of  Brickwork  per  Lineal  Foot. 

4i  In.  Thick. 

9  In.  Thick. 

13^  In.  Thick. 

2   0X3  o 

4.600 

.127 

.287 

.480 

2   4X3   6 

6.261 

•143 

•323 

•533 

2   8X4  0 

8.178 

.163 

.360 

•59° 

3  0X4  6 

10.350 

.180 

•396 

•643 

3  4X5  o 

12.778 

.200 

•433 

.700 

3  8X5  6 

15.461 

.217 

.470 

•753 

4  0X6  o 

18.400 

•237 

.506 

.807 

4  4X6  6 

21.594 

•2S7 

•543 

.867 

4  8X7  o 

25.044 

•273 

•580. 

.916 

5  0X7  6 

28.750 

•293 

.617 

•973 

5  4X8  o 

32.711 

.310 

•653 

1.027 

5  8X8  6 

36.928 

-.33° 

.690 

1.083 

6  0X9  o 

41.400 

•347 

.726 

1.  136 

NOTE.  —  The  quantity  of  brickwork  for  a  new  egg-shaped  sewer  is  from  one  to 
two  per  cent  less  than  that  for  a  standard  egg-shaped  sewer  of  equal  internal  dimen- 
sions, and  for  all  practical  purposes  may  therefore  be  taken  as  equal  to  the  same. 

To  compare  the  amount  of  brickwork  in  circular  sewers  and 
in  egg-shaped  sewers,  Folwell  says  that  the  diameter  of  a 
circular  sewer  having  an  equal  area  with  an  egg-shaped  sewer 
is  1.209  D  where  D  is  the  horizontal  diameter  of  the  egg-shaped 
sewer.  Wollheim  says  that  the  transverse  diameter  of  an  egg- 
shaped  sewer,  of  equal  discharging  capacity  with  a  circular 
sewer  whose  diameter  is  unity,  is  0.8388.  The  latter  also  gives 
this  rule  to  determine  the  relative  proportions  of  an  egg-shaped 
and  a  circular  sewer  to  deliver  equal  volumes,  provided  they 
both  flow  full  and  have  the  same  fall,  viz., 

Diam.  of  circle  :  radius  of  egg-shape  :  :  0.300  :  0.116  or  radius 
of  egg-shape  equals  diam.  of  circle  X  0.39. 

For  further  discussion  of  the  mathematical  elements  involved, 
articles  may  be  found  in  Eng.  News,  Vol.  43,  pp.  259  and  357; 
also  Eng.  News,  Vol.  44,  pp.  28  and  94. 

The  proper  thickness  of  a  brick  sewer  must  be  determined 
chiefly  by  experience.  Up  to  36  inches  diameter  or  2  feet  8  inches 
by  4  feet  o  inches  egg-shape,  in  firm  and  unyielding  soils,  a  half- 
brick  of  four  and  one-half  inches  thickness  is  considered  sufficient. 
In  soft,  yielding  soils,  however,  this  is  not  safe,  and  either  con- 


36  SEWER  CONSTRUCTION 

crete  backing  must  be  used  under  the  haunches  or  the  sewer  made 
9  inches  thick.  An  example  of  a  failure  occurred  during  the 
construction  of  a  2  X  3-foot  brick  sewer  at  Newton,  Mass.,  where 
in  passing  through  quicksand  the  arch  settled  so  much  that  the 
thickness  had  to  be  increased  to  9  inches,  though  elsewhere  4^ 
inches  was  sufficient.  On  the  other  hand,  in  firm,  dry  clay, 
4j-inch  walls  may  be  used  for  even  larger  sewers,  as  the  following 
examples  show: 

At  South  Bend,  Ind.,  the  city  engineer,  by  an  experience  of 
many  years,  has  become  convinced  that  a  4-inch  wall  is  ample, 
and  in  1894  he  wrote:1  "We  continue  to  construct  brick 
sewers  up  to  48  X  68  inches  of  a  single  ring,  that  prove  per- 
fectly stable  in  our  soil."  He  built  a  single  ring  four-foot  sewer 
in  a  i2-foot  trench,  which  in  1893  had  lasted  for  30  years. 
The  48  X  68-inch  sewer  is  in  a  22-foot  trench,  and  seems 
perfectly  stable. 

In  Springfield,  111.,2  the  construction  of  a  y-foot  circular  brick 
4-inch  thick  sewer  was  begun  in  1894,  and  is  probably  the  largest 
single-ring  brick  sewer  ever  built.  The  brick  used  are  side-cut, 
shale  pavers,  and  they  are  laid  in  1:2  cement  mortar.  The 
adoption  of  such  a  doubtful  construction  was  due  entirely  to  a 
small  appropriation  and  to  the  stability  of  the  clay  soil.  Mr. 
Richard,  the  engineer,  says  he  would  not  advocate  the  construc- 
tion of  all  sewers  of  this  dimension  with  a  single  ring,  but  that  in 
many  localities  they  can  be  used  with  a  great  saving  to  the  tax- 
payers. 

Baldwin  Latham  gives  the  following  formula,3  which  he  says 

is  convenient  for  determining  the  proper  thickness :  /  =  -  —  ,  where 

/  is  the  thickness  of  the  brickwork  in  feet,  d  the  depth  of  excava- 
tion in  feet,  and  r  the  external  radius  of  the  sewer  in  feet.  That 
this  formula  can  be  only  approximate  is  apparent  from  its  form, 
no  account  being  taken  of  the  character  of  the  soil  or  of  the  fact 

1  Paving,  Vol.  6,  p.  10. 

3  Paving,  Vol.  7,  p.  17;  Proc.  111.  Soc.  C.  E.,  1895. 

3  Latham's  Sanitary  Engineering,  p.  226. 


BRICK  SEWERS  37 

that  the  thickness  may  increase  indefinitely  with  the  depth  of  the 
cutting. 

Scheffle,  a  noted  French  railroad  engineer,  says,  in  speaking  of 
arch  linings  for  tunnels,  "  I  believe  that  in  earth  of  average  charac- 
ter, the  load  on  the  arch  lining  of  a  two-track  tunnel  never  exceeds 
that  due  to  the  weight  of  the  superincumbent  earth  of  30  to  40 
feet  depth,  and  that  for  a  single-track  tunnel  the  depth  would  be 
considerably  reduced."  In  the  narrow  sewer  trench,  the  depth 
of  earth  furnishing  load  would  be  still  more  decreased,  so  that 
Latham's  formula  would  be  limited  in  its  use  to  depths  within 
that  limit.  Mr.  Barbour  has  made  experiments  on  this  point, 
and  finds  that  with  the  width  of  trench  experimented  on,  from 
3  to  8  feet,  the  percentage  of  the  load  transmitted  to  a  buried 
structure  is  constant  for  a  fill  of  more  than  ten  feet,  and  in  no 
case  below  that  depth  is  the  full  weight  of  the  superincumbent 
earth  carried  to  the  arch.  His  experiments  are  the  only  ones, 
so  far  as  the  author  knows,  on  this  subject,  and  his  conclusions 
are  worth  repeating  here,  since  they  bear  directly  on  the  loading 
to  be  imposed  on  the  sewer  arch.  The  thickness  of  the  arch  ring 
should  be  determined  by  the  loading  on  the  same,  and  therefore 
the  inquiry  into  the  loading  is  pertinent. 

The  experiments1  were  made  in  a  trench  dug  for  the  purpose, 
from  3  to  8  feet  wide,  5  feet  long,  and  1 1  feet  deep.  A  calibrated 
hydraulic  press  was  placed  in  the  bottom  so  arranged  that  the 
pressure  could  be  read  on  the  surface  of  the  ground.  On  the 
press  a  platform  was  built  on  which  the  filling  was  placed.  The 
filling  was  of  loam,  or  sand  and  gravel,  and  the  sides  of  the  trench 
were  sheeted,  left  in  earth  with  vertical  side  and  with  sides  bat- 
tered at  different  angles.  In  one  experiment,  the  sheeting  was 
purposely  roughened  by  nailing  on  cleats.  Mr.  Harbour's  con- 
clusions were  as  follows:  First,  that  the  friction  of  the  earth 
against  the  sides  of  the  trench  has  little  effect,  but  that  the  cohe- 
sion of  the  filling  material  is  the  factor  determining  the  net 
pressure.  Second,  the  cohesion  increases  rapidly  to  a  depth  of 
about  five  feet,  and  from  there  it  changes  slightly  up  to  ten  feet, 

1  Assn.  Eng.  Soc.,  Vol.  19,  p.  193. 


38  SEWER  CONSTRUCTION 

where  it  becomes  almost  constant.  Third,  in  the  case  of  two 
kinds  of  material  the  per  cent  of  the  weight  of  the  superincum- 
bent earth  is  nearly  constant  above  ten  feet  of  filling,  and  is 
practically  the  difference  between  unity  and  the  coefficient  of 
friction  for  the  material  in  question,  viz.,  31  per  cent  for  loam  and 
36  per  cent  for  gravel.  Fourth,  if  this  may  be  considered  a  law, 
and  extended  to  wet  clay  with  a  coefficient  of  35,  the  greatest  per- 


Surface  of  Ground 


Fig.  21 

centage  of  the  weight  of  superincumbent  earth  would  be  65  per 
cent.  Fifth,  the  addition  of  concentrated  loads  on  the  filling 
adds  a  percentage  of  pressure  to  the  pipe,  but  the  increase  is  in  a 
less  ratio  than  that  found  for  the  filling,  so  that  the  filling  ratio  is 
safe  for  any  concentrated  loading. 


BRICK  SEWERS 


39 


Surface     of      Ground 


Fig.  22 


40  SEWER   CONSTRUCTION 

For  the  sake  of  illustration,  the  above  data  may  be  applied  to 
the  selection  of  a  24-inch  pipe  for  an  assumed  trench  in  gravel, 
15  feet  of  cover  on  the  pipe,  the  gravel  weighing  115  pounds 
per  cubic  foot.  The  weight  on  the  pipe  then  is  115  X  2  X  15,  or 


Equilibrium  Polygons. 
—  Sewer  Empty. 


Vert.  Press.of  Earth. 

Resultant  of  Hor.  and 

Vert.  Thrusts  of  Ear.th 


Fig.  23 


3450  pounds  per  running  foot,  and  the  pressure  transmitted  to 
the  pipe  is  3450  pounds  X  36  per  cent,  or  1242  pounds. 
Standard  pipe  should  sustain  a  load  of  3000  pounds  per  lineal 
foot  without  breaking,  but  the  pipe  as  made  in  24-inch  sizes 


BRICK  SEWERS  41 

only  average  about  2000  pounds.  Mr.  Barbour  thinks  that  in 
order  to  allow  for  weak,  cracked,  or  underburned  pipe,  a  factor 
of  safety  of  3  should  be  used,  making  the  safe  load  on  the  pipe 
about  700  pounds  per  lineal  foot.  The  inference  then  is  that 


Fig.  24 


double-strength   pipe    should   be   used,   or    else   some   concrete 
reinforcement. 

For  sewers  larger  than  6  feet  diameter  an  analysis  of  the 
strains  in  the  brick  arch  should  be  made,  together  with  the 
abutment  reactions.  If  the  soil  on  the  side  of  the  trench  is 
not  considered  firm  enough  to  withstand  the  thrust  of  the  arch, 


42  SEWER  CONSTRUCTION 

additional  brickwork  or  other  masonry  backing  must  be  added, 
the  maximum  amount  being  that  necessary  to  act  as  an  abut- 
ment if  the  arch  were  built  entirely  above  ground.  A  thorough 
study  of  the  strains  in  the  arches  of  large  sewers  and  the  neces- 
sary amount  of  masonry  backing  to  take  up  those  strains  was 
given  to  the  intercepting  sewers  of  the  city  of  Philadelphia  by 
Mr.  Rudolph  Hering,  and  described  by  him  in  an  interesting 


Fig.  25 

paper  before  the  American  Society  of  Civil  Engineers.1  Figs.  21 
and  22  show  the  lines  of  pressures  as  determined  for  the  two 
given  arches  with  the  assumed  loading  and  the  variation  in 
the  thickness  of  the  arch  in  order  to  keep  this  line  within 
the  middle  third.  Fig.  23  shows  an  investigation  of  the  same 

1  Trans.  Am.  Soc.  C.  E.,  Vol.  7,  p.  252. 


BRICK  SEWERS 


43 


BRICK  SECTION 


CONCRETE  SECTION 


.1 


'      jj                             0                             0                             ! 

I; 

O 

t 

ll 
*-12*» 

]  I 

^ 

1 
<-12-> 

H 

Spa< 

ngof 
•^S/1 

Bents  3'6*  c.  to 

\ 

c.  of  I 

•"•v/^ 

iles 

J§ub.  grade 


Fig.  26 


Fig.  27 


44 


SEWER  CONSTRUCTION 


sort  but   made   more   complete,   4  different  lines  of  pressures 
being  drawn  for  4  different  sorts  of  loading,  and  the  thickness 


Fig.  28 

being  determined  so  that  the  line  will  fall  within  the  middle 
third  for  all  cases.  The  method  of  analysis  by  which  the  lines 
of  pressure  are  drawn  may  be  found  in  Church's  "  Mechanics," 


BRICK   SEWERS  45 

Chapter  X,  in  Howe's  "  Symmetrical  Masonry  Arches,"  and  in 
many  other  treatises  and  text-books  on  arches. 

If  the  earth  filling  were  perfectly  compacted  and  noncom- 
pressible,  no  thickening  of  the  arch  would  be  necessary,  and 
there  would  be  no  need  of  any  abutment,  the  thickness  of  the 
arch  being  carried  around  uniformly.  Between  this  condition 
and  that  where  the  filling  cannot  be  depended  on  for  any  resist- 
ance, there  are  intermediate  conditions  where  a  partial  backing 
must  be  substituted,  the  amount  of  backing  being  determined 
altogether  by  the  judgment  of  the  engineer.  The  following 
examples  are  given  to  show  the  actual  variation  in  practice,  the 
thickness  being  partly  a  matter  of  the  filling,  and  partly  a  matter 
of  the  caution  or  boldness  of  the  engineer. 

The  section  shown  in  Fig.  24  of  the  Washington,  D.C., 
sewer1  is  used  for  all  sizes  between  2  feet  6  inches  X  3  feet  9 
inches  and  3  feet  3  inches  X  4  feet  ioj  inches,  no  single-ring 
sewers  being  laid.  If  the  soil  is  yielding,  however,  the  invert  is 
made  heavier,  as  shown  in  Fig.  25,  one  row  of  brick  being  cut 
out.  In  these  two  drawings  a  terra  cotta  block  is  shown  in 
the  invert,  flanked  on  each  side  by  six  vitrified  or  paving  brick. 
The  other  brick  shown  are  ordinary  red  building  brick,  the 
whole  surrounded  with  concrete. 

Fig.  26  (on  piles)1,  in  its  left  half  shows  a  brick  section 
for  a  sewer  5  feet  9  inches  diameter,  12  J  inches,  or  three 
brick  thick,  the  placing  of  the  concrete  backing  being  more 
economical. 

Fig.  27  shows  a  section  of  a  seven-foot  brick  sewer  at  Ottawa, 
Can.,  in  rock,  and  illustrates  how  the  uneven  surface  of  the 
rock  may  be  smoothed  up  with  concrete  in  readiness  for  the 
rings  of  brickwork.2 

Fig.  28  shows  a  section  of  the  6-foot  main  sewer  in  New 
Orleans,  the  uncertain  and  water-bearing  soil  requiring  the 
timber  foundation  with  tongue  and  grooved  sheeting.3 

1  Report  of  Eng.  Dep.  of  the  Dist.  of  Col.  for  year  ending  June  30,  1895. 

2  Engineering  Record,  Vol.  40,  p.  600. 

3  Assn.  Eng.  Soc.,  Vol.  27,  p.  199. 


46  SEWER   CONSTRUCTION 

Fig.  29  shows  a  section  of  the  94-inch  Delgany  Street  sewer  in 
Denver,  Col.     A  large  part  of  the  sewer  is  on  made  ground, 


Fig.  29 


Concrete 


Stability  of. the  Excava 


Fig.  30 

and  a  part  of  it  is  above  ground  so  that  the  heavy  section  shown 
was  required.1 

1  Eng.  Nc-ws,  Vol.  34,  p.  430;  Am.  Soc.  C.  E.,  Vol.  35,  p.  102. 


BRICK  SEWERS  47 

Fig.  15,  already  referred  to,  shows  a  section  of  the  sewer 
masonry  in  open  cut  40  X  60  inches  in  Sixtieth  Street  sewer 
tunnel,  Brooklyn.  The  material  is  firm  sand,  carrying  con- 
siderable water;  it  will  not  stand  up  during  excavation,  but  is 
hardly  unstable  enough  to  class  as  quicksand.1 


Fig.  31 

Fig.  30  shows  a  typical  cross-section  of  an  egg-shaped  sewer 
whose  vertical  diameter  is  from  4  to  6  feet.  In  a  rock  trench, 
as  shown  on  the  right  half  of  the  drawing,  concrete  backing  is 
used  in  sufficient  quantity  only  to  fill  up  the  irregularities  of  the 
rock  which  is  excavated  to  fit  the  outside  of  the  sewer.  In 
earth  excavation,  enough  concrete  is  placed  to  act  as  an  abut- 
ment, the  amount  being  made  to  vary  with  the  stability  of  the 
earth.  The  design  shown  is  that  of  the  West  Side  Trunk  sewer 
in  Rochester,  N.  Y.  Fig.  31  shows  a  section  of  the  same 
sewer  at  a  point  where  the  vertical  diameter  is  8  feet  7  inches 
and  the  maximum  horizontal  diameter  is  9  feet  3  inches,  the 
two  conditions  of  backing  being  shown  as  before. 

1  Eng.,  Vol.  46,  p.  272. 


48  SEWER  CONSTRUCTION 

The  brickwork  of  sewers  is  generally  laid  in  rowlock  bond,  so 
called  (see  Fig.  32);  that  is,  the  brick  are  laid  as  stretchers  and 
separately  in  the  different  rings,  the  bond  being  made  up  only  by 


Fig.  32 

the  strength  of  the  cement  between.  For  small  sizes,  the  space  on 
the  outside  of  the  joint,  even  in  single  rings,  is  large,  and  it  is  often 
required  that  pieces  of  slate  or  brick  be  used  to  chink  in  these 
openings.  English  engineers  have  required  the  use  of  specially 
molded  brick  shaped  to  the  proper  radius  of  the  sewer,  but  in 
this  country  this  refinement  has  not  been  considered  necessary. 
In  order  to  distribute  the  pressure  in  the  arch  ring  evenly,  through 
the  different  rings  of  brick,  some  better  bond  than  that  due  to  the 
adhesion  of  the  cement  ought  to  be  provided.  This  can  be  done 
by  laying  a  course  of  brick  as  headers  through  the  arch  at  such 
intervals  as  the  radius  allows,  one  more  brick  in  the  outer  ring 
than  in  the  inner  one.  In  a  3 -foot  sewer  this  is  possible  every 
three  courses,  as  shown  by  Fig.  33,  originally  drawn  to  full  scale. 
In  large  sewers,  the  change  in  length  of  the  inner  and  outer  cir- 
cumference takes  place  more  gradually,  and  the  opportunity  for 
inserting  headers  comes  less  frequently.  A  block  voussoir  may 
be  built  through  the  arch  at  regular  intervals,  and  the  brick  of  the 
different  courses  cut  to  fit  between  the  several  voussoirs.  These 
voussoirs  may  be  of  cut  stone  or  of  brick  built  up  in  the  form  of 
voussoirs  or  headers,  the  former  practice  being  the  better.  The 
question  of  bond  should  be  thoroughly  worked  out  on  paper,  the 
drawing  being  of  large  scale,  so  that  the  bond  may  be  specifically 


BRICK  SEWERS 


49 


Fig-  33 


Fig.  34 


50  SEWER  CONSTRUCTION 

detailed  and  instructions  given  to  the  masons  before  the  work  is 
begun. 

A  cheap  and  useful  reinforcement  is  afforded  by  the  use  of 
strap  iron  laid  about  two  feet  apart  around  the  sewer  between 
the  rings,  with  one  end  turned  up  between  the  brick  of  the  outer 
course,  and  the  other  end  turned  down  between  the  brick  of  the 
next  inner  one.  (See  Fig.  34.) 

The  mortar  for  brick  sewers  is  commonly  made  of  Portland 
cement  mixed  1:3,  the  plaster  coats  being  i  :  i.  Cement  mortar, 
especially  when  wet,  works  with  difficulty  under  the  trowel.  The 
brick  absorb  the  moisture,  and  the  mortar  seems  to  have  no  adhe- 
sion to  the  brick.  If  the  mortar  is  made  very  wet,  the  brick  slide 
out  of  place,  and  it  is  difficult  to  keep  the  walls  to  line  and  grade. 
A  small  amount  of  slaked  lime  not  only  increases  the  density  of 
the  mortar,  but  causes  the  mortar  to  work  more  easily.  Probably 
10  per  cent  of  lime,  based  on  the  weight  of  the  cement,  would  have 
no  bad  effects  on  the  strength  of  the  mortar,  but  would  improve  it, 
both  in  strength  and  density.  Experienced  bricklayers  become 
very  expert  at  laying  sewer  brick,  and  instead  of  1000  or  1500 
brick,  which  is  a  fair  day's  work  on  a  house  wall,  a  good  man  will 
lay  from  2500  to  4000  brick  a  day  in  a  large  sewer.  The  mortar 
is  mixed  thin,  and  the  brick  dropped  into  place  much  as  the  brick 
in  a  street  pavement  are  placed.  The  author  has  seen  a  laborer 
detailed  to  place  the  mortar  by  the  shovelful,  while  the  mason 
handled  the  brick  only,  making  the  joint  by  the  dexterous  shove 
he  gave  the  brick  as  it  was  put  into  place.  Work  is  well  done  by 
this  method,  and  joints  are  well  filled,  and  the*  surface  is  left 
smooth,  the  only  requirement  being  a  form,  or  cradle,  in  which  to 
place  the  brick. 

The  actual  construction  of  a  brick  sewer  involves  little  that  is 
unusual.  The  first  step  is  the  placing  of  the  row  of  brick  which 
is  to  form  the  invert.  In  good  soil  this  is  laid  on  a  bed  of  mor- 
tar placed  directly  on  the  ground.  Then  next  to  this  row,  on 
each  side  consecutively,  the  adjoining  rows  are  placed,  tamping 
dirt  underneath  to  bring  the  top  edge  to  line.  If  it  is  a  two-ring 
sewer,  the  second  ring  follows  three  or  four  courses  behind  the 


BRICK  SEWERS  51 

first,  both  stopping  at  the  horizontal  diameter,  where  the  two 
courses  are  brought  to  a  plane  and  leveled  up.  This  lower  part 
is  allowed  to  set  two  or  three  days,  when  the  arch  centering  is  placed 
and  the  brickwork  of  the  arch  is  built  up.  If  the  ground  is  soft, 
a  concrete  base  must  be  placed  first,  on  which  the  brick  may  be 
supported.  Or  a  timber  cradle  can  be  built,  the  ribs  of  2-inch 
lumber  spaced  about  4  feet,  and  2-inch  lagging  nailed  to  the 
inside,  so  that  it  has  the  form  of  the  outside  of  the  brickwork. 
These  cradles  are  best  made  in  place,  and  carefully  held  to  grade 
while  gravel  is  tamped  under  and  around  them.  The  brick  is 
then  laid  against  these  forms.  The  arch  forms  are  made  in 
lengths  of  from  8  to  16  feet,  so  designed  that  they  can  be  readily 
lowered  from  their  position  against  the  arch,  taken  out,  and  used 
again.  Some  examples  of  arch  forms  are  shown  under  concrete. 


CHAPTER  IV. 
CONCRETE  SEWERS. 

THE  use  of  concrete  in  sewer  construction  is  growing  con- 
stantly, both  in  connection  with  brickwork,  either  for  backing 
or  as  an  integral  part  of  the  sewer  ring,  and  also  separately  in 
cases  where  brick  or  pipe  is  not  easily  available.  For  build- 
ing small  sewers  the  Chenoweth  process  is  convenient,  allowing, 
as  it  does,  a  continuous  mixing  and  placing  of  the  concrete  with- 
out stopping  to  make  or  move  the  necessary  forms.  This 
process  was  used  in  1894  for  building  900  feet  of  24-inch  pipe 
and  a  mile  of  lo-inch  pipe  at  Scarborough-on-the-Hud- 
son.1  The  concrete  was  composed  of  5  parts  broken  stone, 
2  parts  sand,  and  i  part  cement,  and  was  reported  to  have  cost 
for  the  larger  size,  95  cents,  and  for  the  smaller,  30  cents,  per 
foot,  for  the  conduit  alone  in  place,  as  compared  with  97  cents 
and  23  cents  for  the  corresponding  sizes  of  vitrified  tile.  The 
process,  invented  by  Mr.  Alexander  Chenoweth,  of  New  York 
City,  is  described  as  follows:  A  collapsible  mandrel,  held  apart 
by  wedges,  is  placed  on  grade,  and  a  thin  galvanized  ribbon  is 
wound  spirally  around  the  mandrel.  The  concrete  is  tamped 
around  the  mandrel  to  the  proper  thickness.  The  mandrels 
are  then  loosened  and  drawn  forward,  while  the  ribbon  is 
left  in  place  supporting  the  green  concrete.  A  new  piece  of 
ribbon  is  attached  to  that  in  place,  and  wound  around  the  man- 
drels. The  trench  is  filled  with  the  ribbon  of  steel  in  place,  and 
the  ribbon  is  not  moved  for  about  10  days,  when  it  is  with- 
drawn from  the  rear  through  a  manhole.  The  inventor  claims 
that  a  length  of  several  hundred  feet  of  pipe  can  be  freed 

1  Eng.  News,  Vol.  26,  p.  369;  Vol.  31,  p.  81;  Vol.  33,  p.  223;  Vol.  51, 
p.  164. 

52 


CONCRETE  SEWERS  53 

from  the  ribbon  in  this  way.  An  experimental  piece  of  sewer 
built  after  this  patent  in  1891  at  High  Bridge  *,  is  still  in  good 
condition. 

Another  invention  for  making  concrete  pipe  continuously  is 
that  of  Mr.  W.  L.  Ransome,  of  Chicago,  which  has  the  advan- 
tage that  all  the  concrete,  even  that  of  the  invert,  can  be  tamped 
in  place.  The  essential  part  of  the  invention  is  the  mold, 
which  is  cylindrical  but  cut  off  obliquely  at  the  front.2  When 
placed  in  position  in  the  trench,  which  is  trimmed  properly  to 
grade,  the  prow  of  the  mold  is  located  at  the  beginning  of  the 
sewer.  A  cover  box  or  outside  mold  is  laid  on  the  trench 
bottom  at  such  a  depth  below  the  core  mold  as  will  give  the 
proper  thickness  to  the  pipe.  The  cover  box,  drawn  ahead, 
slowly  smooths,  and  by  its  weight  compresses  the  earth  bottom. 
The  core  mold  following,  with  its  long,  oblique  prow,  gives  the 
thickness  to  the  concrete,  which  is  tamped  from  the  front  end. 
A  cover  mold,  also  cut  off  obliquely,  gives  the  thickness  to  the 
top  of  the  pipe.  The  three  molds  are  drawn  ahead  at  a  rate 
corresponding  to  the  rate  of  placing  the  concrete,  and  the  green 
concrete  is  found  to  be  self-sustaining  in  the  smaller  sizes  of  pipe. 
When  the  pipe  is  larger  than  24-inch  diameter  a  modification 
has  to  be  made.  The  top  part  of  the  core  mold  is  made  with 
a  projecting  horn,  on  which  are  strung  half-rings  of  iron.  These 
rings,  supported  by  small  iron  struts,  are  left  behind  at  intervals 
as  the  mold  moves  ahead.  The  struts  are  placed  vertically  and 
horizontally  by  a  boy  who  stays  inside  for  this  purpose. 

This  form  of  mold  has  been  used  at  Oakland,  Cal.,  where 
400  feet  of  cable  conduit  were  laid  per  day,  and  at  Denver, 
Col.,  where  it  was  employed  for  making  7000  feet  of  38-inch 
water  pipe.  In  this  latter  city,  with  a  gang  of  30  men,  perform- 
ing all  their  various  duties  systematically,  the  machine  was 
capable  of  making  about  600  feet  of  pipe  daily,  although  on 
account  of  stoppages  and  delays  the  average  daily  rate  did  not 
exceed  300  feet.  The  proportions  used  were  three  and  three 

1  Eng.  News,  Vol.  26,  p.  369. 

2  Eng.  Rec.,  Vol.  53,  p.  349. 


54  SEWER  CONSTRUCTION 

and  one-half  parts  of  river  gravel  to  one  part  of  cement.  The 
cost  of  the  pipe  was  $1.35  to  $1.50  per  foot,  with  cement  at 
$3.75  per  barrel,  gravel  $1.25  per  yard,  and  wages  $1.75  to  $2.00 
per  day.  The  cost  of  the  same  size  vitrified  pipe,  if  it  could  be 
bought,  would  be  about  $3.00  per  foot  in  place. 

There  has  been  some  attempt  in  the  past  to  make  and  use 
cement  pipe  in  the  same  way  that  sewer  pipe  are  made,  viz., 
singly  in  molds,  afterwards  to  be  jointed  together  in  the  trench. 
Brooklyn  for  many  years  had  the  distinction  of  being  the  one 
city  which  demanded  cement  pipe  for  all  its  sewer  extensions. 
Washington,  D.C.,  uses  cement  in  the  form  of  concrete  largely, 
making  the  pipe  in  place,  and  generally  of  larger  sizes  than 
vitrified  pipe  are  made. 

There  has  been  a  prevalent  opinion  that  a  cement  pipe  was 
likely  to  be  more  porous  and  more  brittle  than  vitrified  pipe, 
and  therefore  to  be  shunned.  Of  late  years,  however,  several 
cement  sewer  pipe  machines  have  been  devised  and  put  on  the 
market,  which  will  probably  result  in  the  increasing  use  of 
cement  pipe.  Formerly,  the  high  price  of  cement  prevented 
competition  with  clay  pipe,  but  in  the  past  few  years  this  does 
not  hold.  There  seems  to  be  no  reason  why  well-constructed 
cement  sewer  pipe  should  not  last  as  long  as  vitrified  pipe, 
unless,  indeed,  subjected  to  acids  which  attack  the  concrete 
matrix.  There  are  good  and  bad  grades  of  cement  pipe, 
and  the  pipe  must  be  properly  made  and  used,  or  the  results 
will  prove  unsatisfactory.  The  possibility  of  weak  and  porous 
spots  in  cement  or  concrete  pipe  is  probably  the  greatest  fault. 
One  shovelful  of  gravel  deficient  in  or  poorly  mixed  with  cement 
makes  a  defect  in  the  pipe  line  which  cannot  be  remedied. 
Where  the  cement  layer  is  as  thin  as  it  must  be  in  a  cement  pipe 
to  compare  with  a  vitrified  clay  pipe,  the  danger  is,  of  course, 
greater  than  with  concrete  in  thicker  layers.  Not  for  a  moment 
even  must  the  vigilance  of  the  inspector  or  the  faithfulness  of 
the  workmen  be  relaxed  if  good  pipe  are  to  be  obtained.  Even 
under  these  conditions,  some  imperfections  are  likely  to  be 
found  in  the  pipe. 


CONCRETE  SEWERS  55 

During  1904,  the  United  States  Geological  Survey  1  conducted 
a  series  of  experiments  on  concrete  pipe,  reinforced  with  steel 
rods.  Seven  pipes  were  made,  each  5  feet  in  diameter,  20  feet 
long,  the  concrete  being  6  inches  thick  in  all  pipes.  The  tests 
were  made  with  the  hope  that  the  pipes  would  show  themselves 
capable  of  withstanding  an  interior  pressure  of  at  least  100  feet 
without  excessive  leakage.  The  materials  were  carefully  mixed 
and  placed,  and  every  precaution  taken  to  secure  good  pipes. 
The  results  of  testing  the  first  two  pipes  were  such  that  the  engi- 
neer in  charge  concluded  that  it  was  practically  impossible  to 
make  a  concrete  pipe  non-porous  without  some  water-proof 
plaster  on  the  inside.  Without  the  plaster,  the  pipes,  though  six 
inches  thick,  leaked  so  much  that  it  was  not  possible  to  get  any 
pressure  in  them.  The  water  leaked  away  faster  than  the 
pumps  could  supply  it.  He  found  the  greatest  leakage  where 
tamping  seams  occurred,  places  where  different  batches  of  con- 
crete met,  and  where  the  tamping  was  not  sufficient  for  thorough 
incorporation.  He  found  it  difficult  to  get  water-tight  joints  with 
short  lengths,  and  insists  that  concrete  pipe  must  have  imperfec- 
tions, many  of  which  cannot  be  easily  avoided.  Altogether  the 
experiments  were  not  favorable  to  concrete  or  cement  pipe,  prov- 
ing without  question  the  supreme  importance  of  eternal  vigilance, 
and,  even  with  it,  the  impossibility  of  obtaining  pipe  good  enough 
to  withstand  any  internal  pressure  without  good  plaster  coating 
on  the  inside. 

Cement  pipes  are  made  by  tamping  a  dry  mixture  of  sand  and 
cement,  either  i  :  3  or  i  :  4,  into  a  vertical  mold.  The  molds 
can  be  removed  at  once  and  are  ready  for  a  second  pipe.  Three 
men  can  mold  and  set  aside  about  4  twenty-four  inch  pipes  and 
9  twelve-inch  pipes  per  hour. 

The  following  table  shows  the  thickness  of  cement  pipe  as  made 
by  the  Miracle  Company,  with  their  estimate  of  quantities  and 
cost.2 

These  figures  were  computed  for  a  i  :  3  mixture,  the  pipe  made 

1  Water  Supply  Papers,  No.  143. 

2  Catalogue  Cement  Machinery  Manufacturing  Company,  Columbus,  Ohio. 


SEWER   CONSTRUCTION 


in  two-foot  lengths,  the  sand  costing  75  cents  per  cubic  yard, 
and  the  cement  $2.00  per  barrel.  Twenty-four-inch  pipe  in  three- 
foot  lengths,  made  by  the  author  for  testing  purposes,  a  few  at  a 
time,  cost  at  the  rate  of  about  50  cents  per  foot. 


Size. 

Thickness. 

Cubic  Feet  of 
Sand  per  Pipe. 

Cost  of  Labor. 

Total  Cost 
per  Foot. 

Inches. 

Inches. 

Feet. 

Dollars. 

Dollars. 

6  

o  324 

o  08 

o  oco 

8  

O    4?2 

o  08 

o  06? 

10  

o  8to 

O    IO 

O    II? 

12  

I  .100 

O  .10 

°-I55 

15  

I  .400 

O.II 

o  .192 

18  

j 

1  .840 

0.13 

0.237 

20  

1.950 

0.13 

°-255 

24  

2 

2.750 

o-i5 

°-343 

3°  

a* 

3.700 

0.17 

0-443 

36  

3 

4.900 

o  .20 

0-575 

At  Coldwater,  Mich.,1  in  the  summer  of  1901,  use  was  made 
of  molded  blocks  for  the  construction  of  the  arch  of  a  3J-foot 
circular  sewer.  The  invert  up  to  the  horizontal  diameter  was  of 
gravel  concrete,  the  roughly  shaped  trench  bottom  serving  as  the 
outside  form.  The  blocks  were  molded  in  advance  of  field  con- 
struction, each  block  being  solid,  24  inches  long  along  the  line  of 
the  sewer,  5!  inches  on  the  intrados,  8  inches  on  the  extrados,  and 
8  inches  through,  or  thick.  The  gravel  cost  but  little,  the  molds 
were  of  wood  lined  with  tin,  and  the  cement  cost  $1.35  per  barrel. 
The  blocks  cost  about  12  cents  each  under  those  conditions,  or  at 
the  rate  of  about  $4.20  per  cubic  yard  for  the  concrete  in  the  form 
of  blocks.  This  is,  of  course,  a  low  price  for  concrete  in  such 
small  forms,  and  it  is  possible  that  under  other  conditions  the  use 
of  brick  might  be  cheaper.  The  only  advantage  of  the  blocks 
over  the  concrete  placed  in  mass  in  the  arch  is  that  the  forms  can 
be  made  somewhat  cheaper,  and  can  be  moved  ahead  as  soon  as 
the  key  block  is  placed.  Otherwise,  this  method  has  no  advan- 
tage over  other  methods. 

The  greatest  use  of  concrete  in  sewer  construction,  however, 
is  not  in  the  form  of  molded  pipe,  nor  yet  of  blocks,  both  made 

1  Eng.  Rec.,  Vol.  48,  p.  101. 


CONCRETE  SEWERS  57 

in  a  factory  and  brought  on  to  the  work,  but  is  in  its  use  at  the 
site  of  the  work.  For  convenience  in  description  its  use  there 
may  be  divided  into  three  classes: 

(1)  Used  alone  in  monolithic  construction. 

(2 )  Used  in  connection  with  brickwork. 

(3 )  Used  in  connection  with  steel. 

The  following  examples  may  be  cited  of  sewers  built  of  con- 
crete alone. 

Fig.  35  shows  concrete  sections  used  at  Washington,  B.C., 
for  12  and  24-inch  pipes.  The  inside  lining  is  a  if -inch  plaster 
coat,  depended  on  to  make  the  sewer  impervious. 

A  monolithic  concrete  storm  sewer  was  built  in  1900  by  the 
Chicago  Transfer  and  Clearing  Company1  to  carry  off  storm 
water  from  their  extensive  railroad  yards.  (See  Fig.  36.)  The 
mixture  was  in  the  ratio  of  92  cubic  yards  stone,  51.5  cubic  yards 
sand,  and  18  cubic  yards  cement.  The  bottom  of  the  trench 
was  trimmed  to  the  outside  of  the  sewer  ring.  The  invert  con- 
crete was  then  put  in  and  tamped  and  carried  up  on  the  sides 
without  outside  forms  until  the  invert  had  an  angle  of  about  140 
degrees.  Then  arch  forms  were  put  in,  the  lagging  being  3  X 
2-inch  stuff,  edges  chamfered.  The  lagging  was  loose  and 
merely  laid  in  place.  Where  necessary,  planks  were  used  to  set 
out  the  side  of  the  trench  and  keep  the  side  concrete  of  the  speci- 
fied thickness.  No  outside  forms  were  used  on  the  arch.  The 
centers  were  easily  removed  by  swinging  about  their  vertical 
diameter.  A  plaster  coat  of  i  :  3  was  used  to  smooth  up  the 
inside  and  to  insure  imperviousness.  The  9o-inch  and  84-inch 
mains  had  a  uniform  thickness  of  wall  of  12  inches;  the  48- 
inch  main,  a  ring  10  inches  thick;  and  the  42  and  36-inch  mains, 
rings  8  inches  thick.  The  excavation  was  mostly  in  blue  clay. 

A  solid  concrete  sewer  3  feet  6  inches  X  2  feet  4  inches  was 
built  in  New  York  City  along  the  subway  between  Fifty-fourth 
and  Fifty-eighth  Streets.2  (See  Fig.  37.)  For  this  sewer,  the 

1  Assn.  Engrs.  Cornell  University,  Vol.  10,  p.  47. 

2  Eng.  News,  Vol.  47,  p.  201. 


SEWER  CONSTRUCTION 


CONCRETE  SEWERS 


59 


concrete  was  placed  in  the  bottom  of  the  trench  until  its  top 
surface  was  within  one-fourth  inch  of  flow  line  grade.  An  inside 
form  was  then  set  and  planks  used  to  form  the  outside  of  the 


Fig.  36 

spandrel.  The  invert  concrete  was  1:2:4,  the  stone  being  broken 
to  pass  through  a  i-inch  ring.  After  the  invert  was  set  and  the 
form  withdrawn,  a  thin  wash  of  cement  was  given  the  inside  to 
perfect  the  smooth  interior.  The  arch  forms  were  then  placed, 
and  filling  was  held  in  place  by  battered  side  boards  braced 
against  the  sides  of  the  trench.  It  was  reported  that  these  sewers 
cost  one-third  less  than  brick  sewers  of  the  same  dimensions, 
and  that  no  variation  from  the  true  grade  was  found  to  be  as 
much  as  .01  foot. 

Fig.  38  shows  the  cross-sections  of  the  concrete  sewers  used 
as  mains  in  Victoria,  B.C.,  as  designed  by  Mr.  Edward  Mohun.1 

The   concrete   was   made   in   the   proportion   of   2j   shingle, 

1  Can.  Soc.,  Vol.  10,  p.  80. 


Fig.  37 


m 

/If 

*  . 


Fig.  38 


CONCRETE  SEWERS 


6l 


2§  sand,  and  i  cement,  the  shingle  and  sand  being  both  taken 
directly  from  the  sea  beach.  The  trenching  was  largely  in  sand, 
and  planks  were  placed  inside  the  trenches  to  form  the  outside 
of  the  concrete  walls.  The  channel  pipe  was  laid  to  grade  and 
the  concrete  tamped  in  tight.  Forms  for  the  inner  surface 
were  then  set,  the  invert  part  first,  and  when  the  concrete 
was  set  and  that  part  moved  ahead,  the  arch  form  was 
placed  and  the  concrete  filled  in.  It  was  stated  that  the  addi- 
tional cost  of  the  concrete  in  this  method  was  more  than  saved 
by  the  use  of  unskilled  labor  in  moving  and  preparing  the  out- 
side forms,  the  lumber  being  removed  and  used  over  and  over. 


14-2  Bricks 


Fig.  39 

A  storm- water  sewer  was  constructed  in  Truro  in  1902,*  which 
possesses  some  noteworthy  features,  the  engineers  being  Lea  & 
Coffin,  of  Montreal  and  Boston.  (See  Fig.  39.) 

The  concrete  used  consisted  of  i  part  cement,  2|  parts  sand, 
and  4^  parts  gravel,  passing  a  2-inch  screen  and  caught  on  a 
sand  screen.  The  determination  of  the  proportions  was  such 

1  Eng.  Rec.,  Vol.  46,  p.  196. 


62 


SEWER   CONSTRUCTION 


Fig.  40 


Fig.  41 


CONCRETE  SEWERS  63 

as  to  give  a  slight  excess  of  sand  and  cement  in  the  voids  of  the 
gravel.  The  centering  was  of  i-inch  planed  and  matched 
pine,  nailed  to  ribs  of  2-inch  planking  spaced  2  feet  apart. 
Along  the  top  on  each  side  of  the  centering  were  placed  two 
2  X  4-inch  hard  wood  "stringers,  between  which  at  every  second 
rib  was  a  2  X  3 -inch  removable  hardwood  brace.  The  centering 
was  made  in  10  and  1 2-foot  lengths,  and  in  halves  hooked 
together  at  the  bottom  and  held  in  place  at  the  top,  while  in 
use,  by  the  hardwood  braces  (shown  in  Fig.  40).  The  concrete 
was  laid  to  grade  in  the  bottom.  The  forms  were  then  set,  and 
planks  laid  on  edge  along  each  side  of  the  trench  as  a  mold 
for  the  outside  of  the  concrete,  held  in  place  by  iron  pins 
driven  into  the  ground.  The  arch,  of  about  124  degrees,  was  of 
brick  laid  on  light  forms. 

A  20  X  30-inch  concrete  sewer,  shown  in  Fig.  41,  was  built  in 
Swampscott,  Mass.,  in  1903,  partly  in  tunnel  and  partly  in  soft 
ground.1  The  concrete  was  1:2:4  gravel.  The  foundation 
concrete  was  first  laid,  then  the  invert  was  built,  its  outside  being 
braced  against  the  sides  and  bottom  of  the  tunnel  or  sheeting. 
The  concrete  backing  was  then  put  in  place  and  the  arch  of  the 
sewer  put  in.  The  lagging  of  i-inch  boards  was  covered  with 
zinc  for  smoothness,  the  sections  being  10  feet  long.  After  the 
concrete  had  fully  set  in  the  tunnel  work,  the  space  was  filled 
with  gravel. 

The  following  additional  typical  cross-sections  are  given  (see 
Fig.  42  and  Fig.  43),  taken  from  the  catalogue  of  the  Blaw  Col- 
lapsible Steel  Centering  Company,  of  Pittsburg,  the  thickness  in 
each  case  being  that  recommended  by  William  B.  Fuller,  City 
Engineer  of  Newport  City,  for  average  practice  in  both  hard  and 
soft  material.  The  same  engineer  gives  the  following  directions 
for  determining  the  proper  proportions  of  concrete,  a  method 
which  is  so  definite  and  direct,  and  at  the  same  time  so  convinc- 
ing, that  it  deserves  the  widest  circulation. 

On  important  work,  where  the  greatest  strength  and  water-tightness  are  desired 
from  the  given  cement,  sand  and  stone,  the  right  proportions  should  be  obtained 

1  Eng.  Rec.,  Vol.  47,  p.  550. 


SEWER  CONSTRUCTION 


Sheet 
vPiles 


Jl  +  C  CHin.3) 


Gravel 


Sheet 


Fig. 42 


CONCRETE   SEWERS 


66  SEWER  CONSTRUCTION 

by  trial  as  follows:  Procure  a  hollow  cylinder,  such  as  a  piece  of  12-inch  pipe, 
and  an  accurate  set  of  weighing  scales.  Weigh  out  the  proportions  you  think 
right  of  cement,  sand  and  stone,  and  mix  thoroughly  with  water  on  an  impervious 
platform,  such  as  a  sheet  of  iron;  then  put  all  the  concrete  in  the  pipe,  stood  on 
end,  tamping  it  thoroughly,  and  measure  the  depth  of  the  concrete  in  the  pipe. 
Now  throw  this  concrete  away  and  clean  the  pipe  and  make  up  another  batch, 
with  the  total  weight  of  cement,  sand  and  stone  the  same  as  before,  but  with  the 
proportions  of  the  sand  to  the  stone  slightly  different.  Measure  the  depth  as 
before,  and  if  the  depth  is  less,  and  the  concrete  still  looks  nice  and  works  well, 
this  is  a  better  mixture  than  the  first.  Continue  trying  in  this  way  until  you  get 
the  least  depth  in  the  pipe. 

This  simply  shows  to  you  that  you  are  getting  the  same  amount  of  material 
into  a  smaller  space,  and  that  consequently  the  material  is  more  dense,  and,  as 
has  been  proved  by  many  experiments,  is  both  the  strongest  and  most  water- 
tight material  possible  to  obtaia  from  the  kind  of  sand  and  stone,  and  the  propor- 
tion of  cement  used  in  the  experiments. 

A  little  trouble  taken  in  this  way  will  often  be  productive  of  very  important 
results.  I  have  known  concrete  to  be  increased  in  strength  fully  200  per  cent  by 
simply  changing  the  proportions  of  the  sand  to  the  stone,  and  not  changing  the 
amount  of  cement  used  in  the  least. 


CHAPTER    V. 
CONCRETE   AND  BRICK  SEWERS. 

THE  use  of  concrete  in  connection  with  brick  marks  a  transition 
stage  between  the  use  of  brick  alone  and  the  use  of  concrete  alone. 
It  allows  the  use  of  the  cheaper  material,  concrete,  in  the  bottom 
where  the  inequalities  of  the  trench  require  adjusting,  and  assigns 
the  brickwork  to  the  arch,  where  such  work  may  be  done  more 


Fig.  44 

easily  and  expeditiously.  The  fact  that  the  invert  is  sometimes 
lined  with  brick  goes  to  show  that  the  designing  engineer  is  still 
afraid  of  the  new  material,  as  to  its  ability  both  to  withstand 
erosion  and  to  present  a  smooth  surface,  a  fear  entirely  unfounded. 
Since  concrete  is  intrinsically  cheaper  than  brick,  and  has 

67 


68 


SEWER   CONSTRUCTION 


besides  the  other  economic  advantages  named,  it  seems  almost 
puerile  to  hesitate  about  its  use  throughout,  and  probably  the 
use  of  brick  and  concrete  together  will  rapidly  decrease. 

The  following  examples  of  the  use  of  concrete  and  brick  may 
be  cited: 

Fig.  44  shows  a  combination   brick   and    concrete   sewer   as 


Fig.  45 


built  in  Medford,  Mass.,  in  1903,  and  Fig.  45  shows  the  forms 
used  in  construction.  The  material  for  the  invert  was  concrete 
1:3:6  bank  gravel,  and  the  arch  was  built  of  one  ring  of  hard- 
burned  brick.  The  forms  used  involved  some  peculiar  features. 
They  were  so  designed  that  the  invert  template,  instead  of  stopping 
at  the  springing  line  of  the  arch,  extended  up  to  planes  at  30 


CONCRETE  AND  BRICK  SEWERS 


69 


degrees  with  the  horizontal.  This  was  done  to  save  brickwork 
of  which  the  arch  was  built,  but  it  resulted  in  the  use  of 
unusually  simplified  forms.  These  were  in  two  parts,  invert 
form  and  arch  form,  both  10  feet  long.  The  invert  forms  were 
made  in  halves,  but  were  firmly  held  together  by  means  of 
malleable  iron  clamps,  which  fitted  over  the  stringers  on  the  inside. 
The  tops  were  held  firmly  and  at  the  proper  distance  apart  by 
iron  rods,  with  turn-buckles  which  allowed  the  forms  to  be  most 
carefully  separated  from  the  concrete.  The  arch  forms  were 
made  of  2-inch  ribs,  spaced  2  feet  apart  and  covered  with  J-inch 
lagging.  This  form  was  held  in  place  at  the  rear  by  heavy  wedges 
on  the  bottom  of  the  form  behind,  and  the  front  end  was  held  up 
by  a  screw  jack  from  the  invert.  These  centers  proved  entirely 
satisfactory,  were  readily  set  up  and  removed,  and  were  handled 
without  the  least  injury  to  the  comparatively  fresh  concrete. 


Concrete 


Fig.  46  and  Fig.  47  show  additional  sections  of  sewers  where 
combinations  of  concrete  and  brick  have  been  used.  Fig.  46 
shows  a  24-inch  sewer  in  soft  ground,  the  concrete  resting  on  a 
timber  platform  and  filling  the  entire  space  between  sheeting 
boards.  The  arch  of  one  row  of  brick  starts  on  a  row  of 


70  SEWER   CONSTRUCTION 

headers  which  mark  its  springing  line.  The  concrete  is  12 
inches  thick  on  the  sides  and  6  inches  thick  on  the  bottom  of  the 
sewers. 


0^4607 


Cement  Mortor 


^_  --75--  "»j 

Fig.  47 

Fig.  47  shows  a  64-inch  sewer  in  firm  ground.  The  concrete 
is  brought  up  higher  than  in  Fig.  39,  the  concrete  is  12  inches 
thick  on  both  bottom  and  sides,  and  fills  the  trench  which  has 
been  carefully  trimmed  out  to  grade. 

At  Altoona,  Pa.,1  a  combination  brick  and  concrete  sewer 
33}  X  44-inch  oval  was  built,  one  ring  of  vitrified  shale 
paving  brick  being  surrounded  by  from  4  to  8  inches  of  con- 
crete. Many  engineers  believe  that  paving  brick  resist  wear 
and  erosion  better  than  concrete,  and  hence  prefer  the  section 
shown  to  one  all  concrete,  the  combination  being  cheaper  than 
two-ring  brick.  (See  Fig.  48. ) 

The  rich  plaster  coat  on  the  outside  of  the  brick  is  of  advantage 
as  tending  to  make  the  walls  of  the  sewer  less  pervious. 

Fig.  49  shows  the  outfall  sewer,  15!  miles  long,  at  Mel- 
bourne, Australia.  This  is  a  circular  sewer  built  of  concrete 

1  Proc.  Engineers'  Club  of  Philadelphia,  Vol.  14,  p.  92. 


CONCRETE  AND  BRICK  SEWERS 


and    brick    as   shown.      A  wooden    platform    is    built    in   the 
bottom    of  the    trench,    and    the  concrete  invert  laid,  with  a 

I 


Stringer  12\  4  " 
V  Stringer  12 'x  4' 

12  "x  3"Planking 
13  '0* 


Fig.  49 

plaster  coat  under  the  brick  lining.      The  arch  is  a  three-ring 
brick  arch,  backed  with  concrete  at  the  haunches.     The 


72  SEWER   CONSTRUCTION 

shaped  section,  shown  in  Fig.  50,  was  also  used  as  a  portion  of 
the  main  sewer.1 


Fig. 50 

Fig.  51  shows  a  section  of  a  large  storm-water  outfall  12  to  14 
feet  wide  by  8  feet  high.  The  arch  is  13  inches  thick,  backed 
with  additional  rings  of  brickwork  at  the  haunches.  The  con- 
crete is  8  inches  thick  at  the  bottom  and  24  inches  thick  on  the 
sides. 

Fig.  52  shows  a  combined  brick  and  concrete  sewer  built  in 
lagging  in  very  wet  sandy  soil.  The  invert  was  first  laid  between 
the  2-inch  sheeting  driven  obliquely  to  shut  off  the  flow  of  sand. 
The  brickwork  was  then  carried  up,  the  concrete  backing  being 
placed  between  the  brickwork  and  the  lagging  as  the  former 
advanced. 

1  Eng.  Rec.,  Vol.  44,  p.  587. 


CONCRETE  AND   BRICK  SEWERS 


73 


^^^^^^^^^^^^^^s^  o— 


Fig.  51 


Portland 
Concrete 


2  Plank 

Tongued  and 

Grooved 


Sand 


Sand 
Very-Wet 


74 


SEWER  CONSTRUCTION 


Fig.  53  shows  a  section  of  the  basket-handled  arch  adopted 
for  the  aqueduct  from  the  Wachusett  Dam  on  the  Nashua  River, 
to  the  Sudbury  River.  The  aqueduct,  about  9  miles  long,  is  n 
feet  6  inches  wide  by  10  feet  5  inches  high,  and  has  a  slope  of  i 


Fig.  53 

in  2500,  and  an  estimated  capacity  of  300,000,000  gallons  per 
day.  The  arch  has  three  rows  of  brick,  cut  down  to  one  where 
the  concrete  backing  is  added.  The  entire  masonry  is  3  feet 
thick  at  the  springing  line  and  about  6  feet  thick  at  the  base. 
This  backing  was,  however,  reduced  in  tunnel  and  in  rock  cuts. 


CHAPTER  VI. 
REINFORCED  CONCRETE   SEWERS. 

THE  tendency  of  construction  is  towards  the  use  of  reinforced 
concrete  for  all  large  sewers.  It  has  many  advantages;  and 
the  great  disadvantage,  the  porosity,  has  not  been  emphasized 
sufficiently  to  act  as  a  drawback.  The  saving  of  expense  is 
very  great,  since  the  additional  cost  of  steel  does  not  equal  the 
cost  of  the  concrete  saved,  except  for  small  sewers,  i.e.  up  to 
3  feet  diameter.  For  these  smaller  sizes  it  is  cheaper  to  increase 
the  amount  of  concrete  slightly  and  omit  the  reinforcement. 
The  steel  is  supplied  in  two  forms,  either  as  a  wire  mesh 
wrapped  around  the  pipe  and  buried  in  concrete,  the  size  of 
mesh  being  from  3  to  6  inches,  or  as  rods  placed  around  the 
pipe  at  intervals  of  about  12  inches  with  longitudinal  rods 
spaced  twice  that  distance.  The  amount  of  metal  needed, 
empirical  entirely,  is  about  the  same  in  the  two  cases,  and  the 
more  intimate  association  of  the  steel  and  concrete  afforded  by 
the  mesh  gives  that  form  of  reinforcement  a  decided  advantage. 
As  a  guide  to  the  amount  of  steel  used,  the  table  on  the  following 
page,  taken  from  the  catalogue  of  the  Jackson  Reinforced  Pipe 
Company,  is  given,  there  being  two  circular  bands  in  each  two 
feet,  and  five  longitudinal  rods  in  the  circumference. 

The  following  examples  of  actual  construction  are  given, 
where  expanded  metal  has  been  used. 

Fig.  54  shows  a  cross-section  of  the  reinforced  concrete 
aqueduct  which  was  built  in  1906  to  supply  the  City  of  Mexico 
with  water.  This  aqueduct  is  about  1 7  miles  long,  and  is  laid  on 
a  grade  of  3  feet  in  10,000,  its  capacity  being  estimated  at 
about  60  cubic  feet  per  second.  The  rock  used  was  a  hard 
basalt,  mixed  in  the  proportion  of  1:3:3,  fine  screenings  being 

75 


76 


SEWER  CONSTRUCTION 


used  in  place  of  sand.  The  maximum  width  is  6  feet  8  inches, 
and  the  maximum  height  is  8  feet  5  inches.  The  thickness  of 
the  crown  is  7  inches  and  of  the  base  12  inches,  the  haunches 
being  thickened  as  shown.  One  layer  of  expanded  metal  was 
used  by  way  of  reinforcement,  and  was  located  in  the  section  as 
shown  in  the  drawing. 


Fig.  54 

A  concrete  sewer  in  Providence  shown  in  Fig.  55  is  reinforced 
with  expanded  metal.  The  sewer  is  36,  48,  and  56-inch  diameter, 
and  for  the  smaller  size  is  but  4  inches  thick  at  the  crown. 
The  expanded  metal  is  No.  14  gauge,  4-inch  mesh.  A  piece 
of  the  metal  18  inches  wide  is  embedded  in  the  invert,  and  then 
the  arch  form  placed.  The  arch  reinforcement  is  then  placed  so 
as  to  lap  the  invert  metal  about  6  inches.  The  concrete  was 
made  of  i  cement  to  9  bank  gravel.  A  portion  of  the  invert, 
where  the  scour  is  greatest,  is  finished  with  a  rich  mixture  and 
troweled  down  like  a  sidewalk. 

During  the  year  1903  a  reinforced  concrete  sewer  was  built  in 
the  city  of  Wilmington,  the  entire  length  being  7436  feet. 


REINFORCED    CONCRETE  SEWERS 


77 


Of  this,  1726  feet  was  9  feet  3  inches  in  diameter,  2426  feet, 
6  feet  6  inches  in  diameter,  1374  feet,  6  feet  in  diameter,  804 
feet,  5  feet  in  diameter,  and  64  feet,  4  feet  9  inches  in  diameter. 


Fig-  55 


The  accompanying  drawings,  Fig.  56,  show  the  cross-sections 
of  the  different  sizes.  The  engineer,  Mr.  Hatton,  calls  atten- 
tion to  the  thin  crown,  only  8  inches  for  9  feet  3  inches  diameter, 
and  to  the  fact  that  it  proved  strong  enough  to  withstand  the 
shock  resulting  from  dumping  a  cubic  yard  of  dirt  and  rock 
from  the  cable  buckets  from  heights  of  from  3  to  10  feet,  and 
the  weight  of  25  feet  of  loose  filling,  without  any  apparent 
fracture.  In  construction,  both  inner  and  outer  forms,  and 


SEWER  CONSTRUCTION 


Fig.  56 


Fig.  57 


REINFORCED    CONCRETE   SEWERS  79 

lagging,  were  used,  the  latter  being  movable  and  placed 
consecutively  from  the  invert  up,  as  the  concrete  was  deposited. 
The  concrete  consisted  of  ij-inch  stones  mixed  with  stone  dust 
and  cement  in  proportion  of  i  cement,  2  dust,  and  6  stone. 
The  reinforcements  for  the  largest  size  consisted  of  expanded 
steel  6  inches  No.  6  gauge,  lapped  i  inch.  The  other  sizes  were 
reinforced  with  a  woven-wire  fabric,  mesh  6  inches  X  4  inches, 
the  wire  being  No.  8  gauge. 

The  Paxton  Creek  intercepting  sewer  at  Harrisburg,  Pa.,1  was 
built  in  1903  to  take  the  sewage  out  of  Paxton  Creek  and  at  the 
same  time  carry  creek  water  enough  to  give  a  self-cleaning 
velocity  on  the  necessarily  small  grade.  The  invert  of  this  sewer 
is  a  short  arc  of  a  circle  with  tangents  on  each  side  which  have  an 
inclination  of  3  to  i  as  shown  in  Fig.  57.  The  larger  section, 
shown  in  the  figure,  is  5  feet  high  by  6  feet  wide,  the  arch 
being  a  parabola  to  the  invert.  The  reinforcement  is  3-inch 
No.  10  gauge  expanded  metal.  The  concrete  was  1:2^:  4^, 
and  the  invert  was  finished  to  the  lines  of  templates  set 
12  feet  apart.  The  arch  centers  were  2j  X  z\  X  J-inch  steel 
angle  bent  to  proper  shape,  spaced  3  feet  4  inches  apart, 
the  lagging  being  2-inch  pine  plank  10  feet  long.  The  thin 
arch  was  subjected  to  a  severe  test  when  a  coal  train  was  derailed 
on  to  the  ground  directly  over  the  trench  with  only  about  5  feet  of 
filling,  but  no  damage  resulted. 

The  following  examples  are  given  to  show  the  construction 
where  longitudinal  and  transverse  rods  have  been  used. 

Fig.  58  shows  a  section  of  reinforced  concrete  conduit  used 
by  the  Jersey  City  Water  Supply  Company.2  The  construction 
was  of  Portland  cement  concrete,  reinforced  with  Ransome  steel 
rods.  The  thickness  of  the  sections,  the  size  of  the  rods  and 
their  spacing,  were  modified  according  to  the  character  of  the 
soil  and  the  depth  of  the  cutting.  Ninety  per  cent  of  the 
conduit,  however,  had  the  arch  5  inches  thick,  the  haunches  n 
inches  thick,  and  the  base  6  inches  thick.  The  reinforcement 
consisted  of  cold  twisted  f-inch  square  steel  rods  bent  to  the 

1  Eng.  Rec.,  Vol.  50,  p.  444.  2  Eng.  Rec.,  Vol.  49>  P-  73- 


8o 


SEWER  CONSTRUCTION 


form  shown  in  the  drawings,  spaced  i  foot  apart,  and  of  J-inch 
longitudinal  rods  spaced  2  feet  apart  and  wired  to  the  transverse 
rods.  The  transverse  rods  were  made  of  such  lengths  as  to 
extend  i  foot  below  the  bottom  of  the  outside  forms,  below 
which  the  concrete  was  built  against  the  hard  earth  or  rock  sides 
of  the  trench. 

TABLE  OF  SIZES  AND  REINFORCEMENT. 


Size  of  Pipe. 

Thickness  of  Wall. 

Size  of  Rods. 

Size  of  Bands. 

Inches. 
24 

Inches. 

Inches. 

IX  J 

Inches. 

27 

3 

X  5 

^j 

X  i 

3° 

3z 

xl 

;X  I 

36 

4 

xl 

;X  I 

42 

4i 

X' 

iXl 

48 

5 

X: 

X  i 

g 

Si 

6 

X: 
X 

1 

^Xi: 
:X  2 

66 

6* 

X 

;X2 

72 

7 

X 

No.  10X2; 

78 

7 

X 

'    No.  10X2: 

84 

7i 

« 

X  \ 

No.  10X2. 

9° 

8 

• 

X: 

No.  10X2; 

96 

»i 

Xi 

No.  10X3 

Fig.  59  shows  the  cross-section  of  a  large  reinforced  concrete 
sewer  built  (1907)  in  the  borough  of  Queens,  New  York  City. 
This  sewer,  nearly  two  miles  long,  varies  in  size  from  2\  to  15 
feet  in  diameter.  The  drawing  shows  the  lo-foot  section, 
larger  sizes  having  a  double  reinforcement,  one  row  at  the 
extrados  and  one  row  at  the  intrados.  In  the  section  shown  the 
transverse  rods  are  ij-inch  Johnson  corrugated  bars  spaced  12 
inches  center  to  center.  The  longitudinal  bars  are  f-inch  and 
are  spaced  18  inches  center  to  center.  The  thickness  of  the 
crown  in  the  section  shown  is  12  inches,  of  the  springing  line 
24  inches,  and  of  the  base  15  inches,  the  minimum  thickness  of 
crown  for  the  smallest  size  being  6  inches. 

Fig.  60  shows  a  storm-water  sewer,  7  feet  in  diameter,  built  in 
Des  Moines,  Iowa,  in  1906,  and  known  as  the  Ingersoll  Run  Sewer. 
In  construction  the  trench  was  dug  to  the  form  of  the  outside  of 
the  invert,  and  transverse  J-inch  steel  bars  were  then  placed  i  foot 


REINFORCED   CONCRETE  SEWERS 


81 


Fig.  58 


Fig.  59 


82  SEWER  CONSTRUCTION 

apart.  The  template  was  then  placed  in  position,  and  the  con- 
crete, a  i  :  2  : 4  mixture,  was  placed  between  the  trench  and  the 
template.  The  invert  being  completed,  the  top  template  was 
placed  upon  the  lower  one,  and  the  steel  bars  were  bent  over  this 
and  wired  together.  Longitudinal  bars,  \  inch  square,  were  laid 
in  the  concrete  as  it  was  built  up. 

Fig.  6 1  shows  the  cross-section  of  the  Harlem  Creek  sewer  in 
St.  Louis,  now  (1908)  under  construction.  The  width  at  the 
point  where  it  empties  into  the  Mississippi  River  is  29  feet  and 
its  center  height  is  19  feet,  making  it  probably  the  largest  con- 
crete sewer  in  this  country.  The  thickness  of  the  arch  is  14 
inches  at  the  center  and  26  inches  at  the  springing  line.  The 
invert  in  earth  is  16  inches  thick  at  the  center  with  a  lining  of 
one  row  of  vitrified  brick.  The  transverse  rods  are  in  double 
rows,  spaced  10  inches  apart  and  J-inch  Johnson  corrugated 
bars  used.  The  longitudinal  rods  are  also  in  double  rows, 
about  3  feet  apart,  and  are  J-inch  bars. 

A  reinforced  concrete  sewer  of  unusual  section  and  strength 
was  built  in  McKean  Street,  Philadelphia,1  in  1901.  As  shown 
in  Fig.  62,  the  bottom  concrete,  supported  on  piles,  was  very  thick, 
and  was  heavily  reinforced  with  steel  bars  in  both  directions,  while 
the  roof  was  a  combination  beam  and  slab  construction.  The  con- 
crete in  the  bottom  and  sides  was  1:3:6,  the  stone  screened  to 
exclude  pieces  of  more  than  i  J  inch,  and  less  than  J  inch.  The  roof 
was  mixed  1:2:5,  an<^  tne  granolithic  coating  was  i  :  i.  The 
reinforcement  in  the  bottom  consisted  of  four  longitudinal  f -inch 
rods,  one  directly  over  each  pile,  with  transverse  J-inch  rods, 
spaced  12  inches  apart.  The  side  reinforcement  consisted  of 
vertical  f-inch  rods,  spaced  12  inches  apart.  The  roof  of  the 
sewer  was  made  up  of  concrete  beams  2  feet  apart,  spanned  with 
slabs  of  concrete  5  inches  thick.  The  beams  have  one  ij-inch 
rod  in  the  bottom,  and  are  13  inches  deep  by  2\  inches  wide. 
This  is  unusually  heavy  construction,  justified  by  the  poor  founda- 
tion, and  by  the  heavy  loading  on  the  surface  just  above  the 
sewer. 

1  Eng.  Rec.,  Vol.  45,  p.  342. 


REINFORCED   CONCRETE  SEWERS 


L,J.  >  L 


Fig.  60 


Fig.  61 


84 


SEWER  CONSTRUCTION 


b) 

£ 


REINFORCED  CONCRETE  SEWERS  85 

Fig.  63  shows  the  forms  and  section  used  in  a  storm-water 
sewer  at  South  Bend,  Ind.,1  built  during  the  year  1906.  This 
sewer  was  from  66  to  81  inches  in  diameter,  the  average 
depth  of  trench  being  about  18  feet.  The  arch  of  the  sewer 
barrel  is  reinforced  with  -j3^  X  i-inch  steel  bands  placed  trans- 
versely 12  inches  apart  on  centers.  These  bands  extend  by 
means  of  a  pin  connection  and  short  anchor  pieces  into  the  con- 
crete of  the  abutment.  The  bottom  of  the  trench  was  shaped 
as  nearly  as  possible  to  the  grade  and  form  of  the  outside 
of  the  sewer.  Braces,  3  feet  apart,  were  cut  and  nailed  on  to  the 
rangers  across  the  trench.  A  vertical  form  shown  in  Fig.  (a)  was 
then  set  up  in  1 2-foot  lengths,  and  fastened  to  stakes  which  were 
driven,  one  on  each  side  at  each  brace  to  further  hold  the  forms 
in  exact  position.  A  template  for  the  invert  of  the  barrel  was  sus- 
pended from  the  cross-braces  and  fastened  as  shown  by  the 
diagonals.  Concrete  was  then  tamped  in  between  the  bottom  of 
the  trench  and  the  invert  form,  and  between  the  two  vertical  side 
forms,  the  concrete  being  left  horizontal  as  shown  in  Fig.  (b). 
The  side  pieces  of  the  reinforcement  bands  were  then  set  in  place, 
and  firmly  held  at  points  A,  Fig.  (b).  Then  two  additional  sec- 
tions were  placed,  one  on  each  side,  and  extending  from  the  inside 
template  up  to  the  springing  line  of  the  arch.  These  pieces  were 
held  in  place  by  a  cross-brace  nailed  to  the  ribs  on  each  side,  and 
by  a  notched  brace  which  fitted  into  the  lower  ends  of  the  ribs. 
The  concrete  was  then  filled  in  between  this  template  and  the  verti- 
cal form  until  it  reached  the  springing  line,  all  as  shown  in  Fig.  (c). 
The  two  sections  of  the  arch  form  were  then  put  in  place,  the  other 
pieces  of  reinforcement  fastened  on,  and  the  forms  on  each  side 
to  hold  the  extrados  were  set.  The  concrete  for  the  arch  was  then 
deposited.  Two  features  of  these  forms  are  noteworthy;  namely, 
the  number  of  sections  into  which  the  forms  are  divided,  conducive 
to  easy  handling  and  rapid  work,  and  also  the  light  sections  of  the 
forms.  The  lagging  is  all  f-inch;  the  ribs  are  4  inches  deep,  cut 
from  2-inch  lumber,  and  are  spaced  3  feet  apart.  Concrete  in  the 
invert  and  in  the  bench  walls  of  the  arch  is  mixed  in  the  propor- 

1  Eng.  Rec.,  Vol.  53,  p.  736. 


86 


SEWER  CONSTRUCTION 


Fig.  63 


REINFORCED   CONCRETE   SEWERS 


Fig.  630 


Fig.  64 


88  SEWER   CONSTRUCTION 

tion  of  i  part  of  cement,  3  parts  sand,  and  6  parts  gravel,  the 
invert  coated  with  J  inch  of  i  to  i  cement  mortar.  The  arch 
concrete  is  made  of  i  part  cement,  2  parts  sand,  and  4  parts 
gravel. 

The  main  intercepting  sewer  of  Cleveland,  extending  along  the 
lake  front  for  a  distance  of  3!  miles,  is  built  of  reinforced  con- 
crete, under  the  Parmlee  patent.1  Figure  64  shows  the  section 
used,  having  2  X  J-inch  steel  bars  as  reinforcement  15  inches 
apart,  with  i|  X  J-inch  longitudinal  bars.  The  feature  of  the 
design  and  of  the  patent  is  the  method  of  inserting  anchor  bars 
in  the  invert  which  are  bolted  to  the  tension  bars  of  the  arch  so 
that  the  form  for  the  arch  can  be  put  in  place  without  difficulty. 

The  concrete  for  the  arch  was  1:3: 7J  with  i  J-inch  screened 
broken  stone,  but  where  the  voids  in  the  stone  exceeded  40  per 
cent  it  was  made  1:3:6. 

1  Eng.  Rec.,  Vol.  48,  p.  247. 


CHAPTER   VII. 
MANHOLES. 

MANHOLES,  as  the  name  would  imply,  are  built  to  allow  access 
to  the  sewer  for  the  purposes  of  inspection  or  cleaning.  For 
this  reason  they  must  be  built  large  enough  to  admit  cleaning 
tools  into  the  sewer;  they  must  be  near  enough  together  to 
admit  of  an  examination  of  the  intermediate  pipe;  and  they 
must  not  introduce  any  element  of  weakness  in  the  sewer  line, 
either  in  the  matter  of  settlement  or  the  admission  of  ground 
water.  Their  construction,  for  purposes  of  description  and 
estimation  of  cost,  may  be  divided  into  three  parts,  —  the  bot- 
tom, the  side  walls,  and  the  cover.  The  cover  of  cast  iron  is 
often,  in  contracts,  separated  from  the  rest  of  the  manhole  work 
and  bought  at  a  fixed  price  per  pound.  The  equity  of  this  is 
evident  when  it  is  noted  that  the  cost  of  the  cover  is  constant 
for  all  manholes,  while  the  cost  of  the  side  walls  varies  with  the 
depth.  Manholes  are  usually  located  over  the  axis  of  the  sewer 
line,  but  with  large  sewers  they  may  be  eccentric,  and  occasion- 
ally they  may  be  built  entirely  separate  and  connected  into  the 
side  of  the  sewer  by  a  horizontal  tunnel  or  by  a  descending 
stairway.  On  pipe  sewers  their  location  is  governed  by  the 
requirements  of  alignment  and  of  grade.  It  is  generally  agreed 
that  the  pipe  should  run  in  a  straight  line  from  manhole  to  man- 
hole (both  vertically  and  horizontally),  and  that  all  connecting 
curves  should  be  entirely  in  manholes.  The  sewer  line  is, 
therefore,  plotted,  on  the  street  plan  (in  chords  where  the 
streets  are  curved),  and  the  manholes  located  at  the  angles. 
The  changes  of  grade  are  fixed,  if  possible,  to  take  place  at 
these  points;  otherwise  additional  manholes  must  be  located. 
Manholes  are  always  placed  at  the  intersections  of  sewers,  and 

89 


90  SEWER  CONSTRUCTION 

generally  at  street  intersections.  Finally,  they  should  not  be 
more  than  400  feet  apart,  although,- to  save  expense  on  trunk 
lines  with  good  grade,  this  distance  is  often  increased  to  600 
feet.  On  brick  sewers,  large  enough  for  a  man  to  enter,'  man- 
holes are  less  frequent.  The  depth  of  the  sewer  affecting  the 
cost  of  the  manholes  should  be  a  factor  in  determining  their 
frequency.  One  thousand  feet  may  be  fixed  as  the  maximum 
distance  under  the  best  conditions. 

The  cross-section  of  a  manhole  is  generally  bottle-shaped 
(see  Fig.  65),  carried  up  vertically  from  the  bottom  for  about 
five  feet,  and  then  in  the  remaining  distance  contracted  in  a 
reversed  curve  so  that  at  the  top  it  will  be  about  2  feet  in  diam- 
eter. Generally  the  ends  of  the  brick  are  kept  horizontal, 
although  some  engineers  prefer  to  keep  the  ends  normal  to  the 
side  lines,  a  method  which  the  author  believes  to  give  the  better 
construction. 

In  very  cold  climates  it  is  advisable  to  avoid  vertical  walls  at 
the  top,  and  to  bring  the  side  walls  up  as  the  frustum  of  a  cone. 
At  Brockville,  Ont.,1  during  a  severe  winter,  the  frost  in  its 
expansion  by  holding  the  earth  tightly  against  the  cover  cracked 
the  brickwork  just  below  the  cover  in  a  manhole  shaped  like 
Fig.  656,  and  the  manholes  were  taken  down  and  rebuilt  as  in 
Fig.  650,  in  order  to  avoid  future  trouble  of  that  sort. 

In  shallow  trenches  it  is  difficult  to  form  any  reversed  curve, 
and  in  such  places  the  beds  are  kept  perpendicular  to  the  side 
lines  of  the  manholes,  and  the  covers  cast  with  the  bottoms 
inclined  so  that  the  covers  will  form  a  keystone  of  a  vault.2  (See 
Fig.  66.) 

The  bottom  may  be  formed  of  either  brick  or  concrete,  and 
consists  of  a  channel  for  the  flow  of  the  sewage,  with  a  platform 
or  floor  on  each  side  of  this  channel  on  which  to  stand.  If  the 
manhole  is  located  by  the  requirements  of  distance  alone,  allow- 
ing access  to  a  straight  line  of  pipe,  and  there  are  no  lateral 
sewers  entering,  the  most  convenient  channel  is  formed  of  a 

1  Eng.  Rec.,  Vol.  27,  p.  97. 

2  Report  on  Sewerage  of  Santos,  Brazil. 


MANHOLES 


bo 


92  SEWER   CONSTRUCTION 

split  pipe  bedded  in  concrete,  the  smooth  interior  of  the  pipe 
making  a  most  desirable  surface.  (See  Fig.  67.)  In  other  cases 
the  channel  must  be  formed  of  brick  or  shaped  in  concrete. 


Fig.  66 


Fig.  67 

When  of  brick,  the  bottom  is  formed  by  laying  the  lowest  course 
through  first  on  edge,  the  top  of  this  course  being  lined  in 
between  the  ends  of  the  pipe  already  in  place.  Other  rows 


MANHOLES 


93 


conforming  to  the  curvature  of  the  pipe  are  added  on  each  side 
up  to  the  horizontal  diameter.  (See  Fig.  68.)  The  bricks  are 
then  laid  up  vertically  as  far  as  the  top  of  the  pipe.  At  this 
level  the  floor  is  paved  out  horizontally  far  enough  to  make  a 
foundation  for  the  side  walls.  When  concrete  is  used,  it  is 


Fig.  68 

thrown  in  to  a  depth  of  about  six  inches  under  the  invert  grade 
and  then  shaped  to  form  the  channel  and  the  floor.  Exact 
forms  may  be  used  for  this,  but  if  the  concrete  is  dry  it  may 
readily  be  formed  by  hand  into  the  shape  required. 

The  size  of  the  floor  area  varies,  according  to  the  size  of  the 
pipes  entering  the  manholes,  the  smallest  size  being  that  on  a 


94  SEWER   CONSTRUCTION 

straight  line  of  6-inch  pipe.  The  limit  is  placed  by  the  room 
required  for  entering  and  working  in  the  manhole,  and  this  may 
be  fixed  at  an  oval  shape,  3  feet  by  4  feet  inside,  the  longer  dimen- 
sion being  along  the  axis  of  the  pipe.  Manholes,  where  laterals 
enter,  require  more  room,  and  a  circular  plan,  4  feet  in  diameter, 
may  be  fixed  as  the  minimum.  Rectangular  sections,  while  more 
symmetrical  and  capacious  in  appearance,  have  really  additional 
room  only  in  the  corners,  where  it  is  not  useful,  and  since  they 
require  more  brick  and  are  not  as  strong  as  the  other  forms,  they 
are  little  used.  The  choice  between  the  circular  and  oval  shape 
must  be  made  according  to  the  special  requirements  of  each  man- 
hole. As  the  sizes  of  sewers  increase  from  a  6-inch  sewer,  the 
size  of  the  manholes  must  also  be  increased,  a  plan  drawn  to 
scale  of  the  pipes  entering  the  manholes  being  a  satisfactory  way 
of  determining  the  proper  size.  For  example,  to  determine  the 
proper  size  of  a  manhole  to  be  built  where  a  24-inch  sewer 
turned  at  right  angles,  and  at  the  same  time  was  entered  by  a 
i6-inch  pipe,  a  sketch  was  made  and  the  plans  as  shown  adopted. 
(See  Fig.  69.)  To  secure  good  results  in  the  flow,  the  con- 
necting curves  in  the  laterals  and  main  should  be  of  such 
radius  as  to  carry  the  flow  line  well  into  the  main,  allowing  the 
streams  to  mingle  smoothly.  Care  should  be  taken  that  the 
brickwork  in  the  projecting  tongue  be  not  too  sharp  to  be  strongly 
built.  As  small  pieces  of  brick  are  easily  dislodged,  cut  stone 
may  be  used  to  advantage  to  give  stability  to  the  end  of  the 
tongue. 

The  walls  of  a  manhole  are  generally  9  inches  thick,  though 
occasionally,  where  there  is  no  frost  and  where  the  soil  is  firm, 
4§-inch  walls  have  been  used.  Where  the  manhole  is  deep,  how- 
ever, or  where  the  soil  is  wet  and  unstable,  13  or  ly-inch  walls 
should  be  used.  The  author  had  an  experience  of  a  9-inch  man- 
hole wall  broken  entirely  across  just  above  the  sewer  and  the 
manhole  itself  moved  laterally  a  few  inches  by  unequal  filling 
around  the  manhole.  Another  experience  was  with  a  manhole 
built  on  the  edge  of  a  stream,  the  manhole  being  13  inches  thick 
to  within  $  feet  of  the  top  and  9  inches  thick  for  that  distance.  A 


MANHOLES 


95 


'\    < 


Fig.  69 


96  SEWER   CONSTRUCTION 

period  of  high  water  in  the  fall  brought  ice  pressure  to  bear 
against  the  manhole  at  the  top,  and  the  wall  was  broken  just  above 
the  point  where  the  p-inch  wall  began. 

In  soft  ground  it  may  be  necessary  to  provide  artificial  founda- 
tion for  the  manhole,  and  care  must  be  taken  to  have  the  manhole 
bring  the  same  unit  loads  on  the  ground  as  the  pipe.  For  example, 
a  24-inch  pipe  half  full  weighs  about  700  pounds  per  running  foot, 
or  has  a  pressure  of  350  pounds  per  square  foot  on  the  soil.  A 
manhole  20  feet  deep,  6  feet  in  diameter,  weighs  about  22,000 
pounds,  and  if  uniformly  distributed  over  the  bottom  gives  a 
pressure  of  about  800  pounds  per  square  foot,  or  more  than  double 
the  pipe  load.  In  soft  ground  this  would  cause  the  manhole  to 
settle  away  from  the  pipe,  breaking  it  off  where  it  enters  the  man- 
hole. This  can  be  avoided  only  by  increasing  the  area  of  the 
manhole  floor,  either  by  a  concrete  steel  foundation,  or  by  a  timber 
platform.  With  a  smaller  pipe  the  difference  is  still  greater, 
and  when  the  ground  is  soft  special  precautions  must  be  taken 
to  equalize  the  pressure. 

When  a  manhole  is  built  into  a  sewer  3  feet  or  more  in  diameter, 
no  special  foundation  for  the  manhole  is  needed,  but  the  side  walls 
start  from  the  side  walls  of  the  sewer.  The  bonding  of  the  lower 
courses  of  the  manhole  into  the  brickwork  of  the  sewer  must  be 
carefully  done,  the  mere  setting  of  a  manhole  on  top  of  the  sewer 
and  a  hole  broken  in  the  top  of  the  sewer  not  being  admissible 
construction.  Where  the  sewer  is  larger  than  6  feet,  the  man- 
hole has  one  side  wall  tangent  to  the  sewer  barrel,  and  the  other 
side  ends  on  top  of  the  sewer.1  (See  Fig.  70.)  For  this  con- 
struction two  rings  of  brick  should  be  built  in  the  sewer  arch  to 
such  a  template  that  they  will  form  the  bottom  of  the  manhole. 
See  Fig.  71  for  drawing  of  such  a  construction  as  is  here  described. 
A  wooden  cylinder  may  be  set  vertically  at  the  right  position  pro- 
jecting up  through  the  arch,  and  the  regular  courses  of  brick 
brought  up  against  the  rows  of  brick  set  around  the  cylinder. 
A  pattern  could  be  made  for  the  line  of  intersection  of  the  two 
cylinders,  which  would  answer  the  same  purpose. 

1  Eng.  News,  Vol.  49,  p.  8. 


MANHOLES 


97 


Occasionally,  engineers  prefer  to  place  the  axis  of  the  manhole 
directly  over  the  center  line  of  the  sewer,  as  shown  in  Fig.  72.* 
The  intersection  in  this  case  probably  contributes  less  to  the  weak- 
ness of  the  sewer  arch,  but  the  function  of  the  manhole  in  giving 
ready  access  to  the  sewer  is  much  decreased  in  value.  A  portable 
ladder  is  necessary  to  get  to  the  invert,  while  with  the  side  support 
the  steps  are  built  in  to  the  bottom. 


5'0 


CROSS  SECTION 


LONGITUDINAL  SECTION 


Fig.  70 


Special  forms  of  manholes  are  needed  when  the  entering  pipes 
are  on  different  levels,  that  is,  when  some  special  device  is  needed 
to  bring  the  sewage  from  the  laterals  into  the  main.  The  most 
common  method  is  to  bring  the  sewage  down  through  a  vertical 

1  Eng.  News,  Vol.  49,  p.  8. 


98 


SEWER   CONSTRUCTION 


MANHOLES 


99 


pipe,  and  then  through  a  go-degree  bend  into  and  in  the  direction 
of  the  flow  of  the  mainstream.1  (See  Fig.  73.)  This  vertical  pipe 
may  be  brought  down  either  on  the  inside  or  on  the  outside  of  the 


Fig.  72 


manhole,  in  both  cases  the  horizontal  pipe  being  prolonged  by  a 
T  through  the  manhole  wall  for  inspection  purposes.  The  advan- 
tage of  the  first  method,  Fig.  73,  is  that  the  vertical  pipe  is  secured 
to  the  manhole  and  is  supported  by  it  so  that  the  connection  is 
more  stable.  On  the  other  hand,  it  occupies  a  large  amount  of 
room  in  the  manhole,  requiring  the  latter  to  be  built  larger  than 
where  no  such  construction  exists.  The  advantage  of  the  second 
method,  Fig.  74,  is  that  no  room  in  the  manhole  is  usurped,2 

1  Report  on  Sewerage  of  Santos,  Brazil. 
.2  Eng.  News,  Vol.  35,  p.  338. 


IOO 


SEWER  CONSTRUCTION 


ELEVATION 


Fig.  73 


MANHOLES 


IOI 


but  unless  the  bottom  of  the  vertical  pipe  is  well  supported  the 
settlement  of  the  pipe  is  different  from  that  of  the  manhole,  and 
they  break  apart.  In  both  cases 
the  invert  of  the  bend  should  be 
placed  at  the  height  of  the  average 
surface  in  the  main  in  order  to  pre- 
vent deposits  in  the  bend.  Instead 
of  a  vertical  pipe,  an  inclined  pipe 
coming  out  of  the  lateral  by  a  Y  may 
be  used.  Thus  greater  velocity  on 
entering  the  main  is  secured,  but 
this  advantage  is  discounted  by  the 
great  difficulty  of  supporting  the 
inclined  pipe  (Fig.  75).  To  avoid 
the  erosion  which  takes  place  when 
a  free  fall  of  water  occurs,  a  pool 
of  sewage  may  be  provided  at  the 
bottom  of  the  manhole  into  which 
the  fall  is  made,  as  shown  in  Fig. 
76.  This  is  the  design  adopted  at 
Melbourne,  Victoria,  and  provides 
a  pocket,  in  which  an  accumula- 
tion of  water  is  retained.1 

In  some  cases,  as  in  Fig.  77,  a 
series  of  steps  are  provided  to  re- 
duce the  fall,  the  illustration  show- 
ing it  in  one  of  the  main  sewers 
at  St.  Louis.  For  laterals  the  same 
principle  may  be  used,  dropping 
the  grade  in  steps  instead  of  by  a 
vertical  pipe.  The  St.  Louis  steps 
shown  were  in  an  8-foot  sewer, 

r  ig.  74 

ii J    feet    high,    with   the    bottom 

steps  on  which  the  scour  would  occur,  of  oak.     The  steps  them- 
selves were  stone.2 

1  Eng.  Record,  Vol.  44,  p.  586. 
1  Eng.  Rec.,  Vol.  26,  p.  345. 


102 


SEWER  CONSTRUCTION 


Fig.  78  shows  a  manhole  65.8  feet  deep,  as  built  at  Cleveland, 
Ohio.  To  prevent  the  erosion  that  would  be  caused  by  a  stream 
of  sewage  falling  freely  through  that  distance,  slabs  of  stone 
flagging  were  built  into  the  manhole  in  such  a  way  that  the  sewage 
would  be  checked  constantly  in  velocity  as  it  fell  from  one  to 
another  of  the  stone  slabs.  The  stone  was  2  brick  thick,  and  the 
slabs  were  spaced  5  feet  apart  vertically. 


;  •<       '      :-~::'i£.*:.+- 

L__ ^_:_^ j^i-^'.  \ 


Fig.  75 

Manholes  in  which  gates  or  valves  are  to  be  placed  have  usually 
to  be  built  with  one  side  wall  vertical,  as  in  Fig.  73,  and  such 
special  manholes  should  always  be  carefully  drawn  out  before 
construction  commences. 

The  frames  and  covers  of  manholes  are  made  of  cast  iron, 
and  together  weigh  from  300  to  400  pounds.  They  have  various 
shapes  according  to  the  fancy  of  the  designer,  and  their  weight 


Fig.  77 


103 


104  SEWER  CONSTRUCTION 

varies  with  the  thickness  and  amount  of  ribbing  in  the  cover, 
and  also  with  the  height  of  the  frame.  The  cover  is  usually 
made  one  inch  thick,  is  stiffened  with  ribs  underneath,  roughened 
with  knobs  on  top.  It  may  be  pierced  with  i-inch  holes,  as  the 
engineer  believes  in  sewer  ventilation  or  not.  The  frame  for 
paved  streets  is  made  deep  enough  to  take  a  paving  block  between 
its  top  and  base,  or  about  8  inches  for  stone.  For  a  brick  or 
asphalt  pavement  this  depth  might  well  be  reduced  to  4  or  5 
inches,  some  depth  being  necessary  to  secure  enough  weight  to 
keep  the  frame  from  being  displaced  and  to  spread  its  base  on 
to  the  top  of  the  brick  walls.  Figs.  79,  80,  and  81  show  three 
different  patterns  of  frame  and  cover. 

Fig.  79,  from  the  Report  on  the  Sewerage  of  Santos,  Brazil,  by 
E.  A.  Fuertes,  shows  the  top  and  bottom  of  the  cover  designed  for 
that  city.  It  has  an  elaborate  system  of  ribbing,  and  a  lock  to 
be  described  later. 

Fig.  80  shows  a  Standard  form  of  manhole  made  by  the  Sessions 
Foundry  Company  of  Bristol,  Conn.,  known  as  the  New  York 
Standard  Manhole.  As  made,  the  total  weight  is  650  pounds, 
exceptionally  heavy,  and  massive. 

Fig.  81  shows  the  manhole  cover  recently  shown  in  contract 
drawings  for  the  construction  of  a  part  of  the  sewer  system  of 
Auburn,  N.Y. 

Provided  the  freight  is  not  excessive,  it  is  entirely  feasible  to  buy 
frames  and  covers  direct  from  large  foundries,  where  it  is  cheaper 
than  buying  from  local  foundries.  By  specifying  the  required 
weight  of  cover  and  frame  they  may  be  made  as  strong  as  desired. 
If  they  are  designed  by  the  engineer  to  be  cast  in  local  foundries, 
care  must  be  taken  to  so  arrange  the  sections  and  surfaces  that 
they  may  be  readily  molded  and  cast;  and  it  is  wise  foresight  on 
the  part  of  the  engineer,  unless  he  has  had  special  experience  in 
designing  castings,  to  submit  his  plans  to  a  practical  foundry- 
man  before  their  formal  adoption.  To  facilitate  molding,  the 
stiffening  ribs  should  not  be  so  deep  or  so  close  together  that  the 
sand  clings  and  breaks  off  from  the  rest  of  the  mold,  as  will  be 
the  case  unless  the  ribs  have  a  good  batter  and  are  separated 


MANHOLES 


105 


Fig.  79 


II      \  ^   /        \    ^  ^  I       \-  II    :^v| 


I 


Fig.  80 


io6 


SEWER   CONSTRUCTION 


enough  to  give  adhesion  at  the  bases  of  the  projecting  sand.  It 
may  also  be  noted  that  if  patterns  have  to  be  made  for  the  covers 
of  special  manholes  of  which  only  one  or  two  are  wanted,  a  large 
proportion  of  the  cost  of  the  cover  is  the  cost  of  the  pattern,  and  by 


Fig.  8 1 


simplifying  the  latter,  a  noticeable  saving  may  be  effected.  For 
example,  over  screening  chambers  or  tanks,  where  a  large  opening 
may  be  wanted,  a  square  cover  would  cost  from  $5.00  to  $10.00 
less  than  a  round  one,  on  account  of  the  relative  cheapness  of 


MANHOLES 


107 


the  square  pattern.  In  places,  also,  where  heavy  traffic  is  not 
anticipated,  as  in  fields  or  over  filter  beds,  the  weight  of  the  regular 
cover  may  be  much  reduced.  There  are  occasional  instances  of 
broken  covers,  but  the  breakage  is  due  generally  to  frost,  and 
only  occasionally  to  a  sharp  blow  from  a  heavily  loaded  wagon. 

There  is  a  story  of  a  horse  breaking  the  cover  of  a  large  man- 
hole in  Washington  with  his  hind  feet,  and  thereby  precipitating 
himself  backwards  into  the  sewer;  but  such  accidents  are  rare. 


Fig.  82 

Covers  should  be  loose,  not  wedged  fast  in  the  frame,  and 
should  be  supported  at  three  points,  so  that  they  will  rest  firmly 
in  place. 

Some  engineers  have  designed  covers  with  simple  locks,  so 
that  mischievous  men  and  boys  may  not  lift  them  from  place. 
The  author  believes  from  his  experience  that  a  lock  is  unneces- 
sary, the  i5o-pound  weight  being  ample  insurance  against 
careless  interference.  Locks  will  rust  or  otherwise  stick.  A 
cover  must  sometimes  be  removed  when  a  key  is  not  at  hand, 
and  the  mechanism  adds  to  the  cost.  Figs.  82  and  83  show 
two  of  the  simplest  forms  of  such  locks. 


io8 


SEWER  CONSTRUCTION 


Fig.  82  is  the  lock  designed  by  Rudolph  Hering  for  the  manholes 
at  Ithaca,  N.Y.,  the  eccentric  lug  shown  falling  by  its  own  weight 
so  as  to  engage  in  a  hole  left  in  the  casting  of  the  manhole  frame. 


Wrought;  Iron 


Sliding  Bar 


To  unlock,  a  curved  lever  is  inserted  through  an  opening  left  for 
the  purpose  and  the  lug  pushed  back  until  the  cover  is  lifted. 
Fig.  83  shows  the  lock  used  at  Salt  Lake  City1  similar   in 

1  Eng.  News,  Vol.  31,  p.  10. 


MANHOLES 


I09 


principle,  but  the  lock  in  this  case  is   a   sliding   bar,   working 
through  slots  on  bolts  attached  to  the  manhole  cover. 

Where  the  covers  are  perforated,  it  is  customary  to  suspend 
pans  just  below  the  cover  in  order  to  arrest  the  street  dirt  from 


Fig.  84 

falling  into  the  sewer.  The  author  doubts  the  necessity  for 
this  practice,  since  the  amount  thus  reaching  the  sewer  is  ordi- 
narily very  small,  and  should  be  carried  on  by  the  sewage  with- 
out causing  any  difficulty.  If  water  finds  its  way  through 


Fig.  85 

the  covers,  it  fills  the  pans,  and  in  overflowing  carries  the  street 
dirt  with  it  into  the  sewer.  Small  openings  in  the  pan  about 
3  inches  above  the  bottom  are  of  advantage  in  getting  rid  of  the 
water  and  leaving  the  dirt.  Figs.  84  and  85  show  the  pans 


no 


SEWER   CONSTRUCTION 


designed  for  Ithaca,  N.Y.,  for  deep  and  shallow  manholes 
respectively,  and  Fig.  86  shows  the  pan  as  built.  It  is  made  of 
galvanized  iron,  No.  20  gauge,  and  is  suspended  by  three  straps 


Fig.  86 


Fig.  87 

resting  on  the  top  of  the  frame  in  depressions  cast  there  for 
that  purpose.  These  pans  cost  about  50  cents  each  and  have 
proved  satisfactory.  Fig.  87  shows  a  more  elaborate  and 
heavier  type.1 

1  Baumeister,  p.  244. 


MANHOLES 


III 


Lampholes  are  occasionally  used  to  reduce  the  expense,  but 
in  the  opinion  of  the  author  their  use  is  seldom  justified.  They 
consist  of  a  6-inch  or  8-inch  pipe  brought  up  vertically  (by 


Fig.  88 

means  of  a  T  branch)  to  the  surface  and  protected  there  by  a 
cast-iron  cover.  The  lamphole  is  supposed  to  have  two 
functions,  viz.,  to  allow  a  lantern  to  be  lowered  into  the  sewer, 
the  light  of  which,  seen  from  a  manhole  each  side,  assures  the 


112 


SEWER  CONSTRUCTION 


freedom  of  the  pipe  from  obstructions;  and  to  enable  fire  hose  to 
discharge  water  for  flushing  into  the  sewer.  For  such  purposes 
lampholes  are  placed  at  points  intermediate  between  manholes 
where  the  grade  or  line  changes  and  where  the  distance  between 
the  manholes  is  so  short  that  an  intermediate  manhole  seems  an 
unnecessary  expense.  In  the  experience  of  the  author,  lamp- 
holes  are  little  used,  and  the  economy  is  not  proved.  He 
would  always  use  manholes  as  being  altogether  more  satisfac- 
tory, as  will  readily  be  acknowledged  should  any  obstruction 
occur  in  the  line  in  question.  The  additional  expense  of  man- 
holes over  that  of  lampholes  is  only  a  very  small  percentage  of 
the  total  cost  of  the  system.  As  temporary  endings  for  laterals 
which  will  later  be  prolonged,  he  believes  lampholes  are  useful, 
but  elsewhere  he  prefers  manholes.  Fig.  88 l  shows  the  con- 
struction of  a  lamphole,  and  how  the  weight  of  the  vertical  pipe, 
which  might  otherwise  crush  down  the  sewer  pipe,  is  supported 
by  concrete.  To  still  further  save  expense,  the  upper  end  of  the 


Fig.  89 

pipe  is  sometimes  covered  with  a  stone  and  left  buried  a  foot  or 
so  below  the  street  surface,  the  place  being  referenced  so  as  to 
be  found  readily.  Otherwise  a  cast-iron  cover  must  be  pro- 
vided, not  touching  the  pipe,  but  free  to  settle  independently,  as 
shown  in  Fig.  89.* 

1  From  Auburn  contract  drawings.     J.  W.  Ackerman,  City  Engineer. 


CHAPTER   VIII. 
CATCH-BASINS. 

WHERE  the  system  of  sewers  is  "combined,"  i.e.  designed  to 
receive  both  domestic  sewage  and  storm  water,  or  where  the 
system  is  for  storm  water  alone,  adequate  means  must  be  pro- 
vided for  the  admission  of  such  storm  water  into  the  sewer. 
This  is  commonly  done  by  making  openings  in  the  gutter  so 
that  the  water  flowing  there  will  be  intercepted  and  led  off  in  a 
pipe  to  the  sewer.  There  are  a  number  of  variations,  however, 
in  the  method  by  which  this  is  done,  as  the  following  discussion 
and  illustrations  will  show: 

The  location  of  the  inlet  is  usually  at  or  near  the  street  corner 
in  order  that  the  rush  of  storm  water  across  a  street  may  be 
avoided.  For  example,  in  Fig.  90,  the  grades  of  the  street  being 
represented  by  the  arrows,  water  coming  down  the  gutters  on 
A  Street  would  flow  across  B  Street  unless  intercepted  at  the 
points  C  and  D.  If  so  intercepted  no  inconvenience  is  experi- 
enced by  pedestrians  on  the  crossing  below,  and  no  channel  is 
required  across  B  Street,  a  great  advantage  to  drivers.  Simi- 
larly, to  avoid  a  rush  of  water  across  A  Street  from  left  to  right 
inlets  should  be  provided  at  E  and  F.  One  inlet  at  G  might 
take  the  place  of  E  and  C,  but  the  water  would  then  have  to  be 
led  across  or  under  both  cross-walks. 

This  arrangement  will  be  modified  by  the  topographical  con- 
ditions. On  the  summit  of  a  hill  no  inlets  would  be  needed. 
In  the  center  of  a  depression  8  inlets  would  be  needed,  and 
intermediate  numbers  would  correspond  to  intermediate  con- 
ditions. The  method  of  construction  of  these  inlets  depends 
upon  the  use  or  non-use  of  catch-basins.  Since  gutter  water 
presumably  carries  large  quantities  of  sand,  gravel,  leaves, 

"3 


114  SEWER  CONSTRUCTION 

sticks,  manure,  and  other  street  debris,  engineers  in  the  past 
have  constructed,  in  connection  with  the  street  inlets,  pits  or 
basins  through  which  the  gutter  water  should  pass,  and  by  the 
reduced  velocity  deposit  such  debris.  But  in  view  of  the 
expense  of  such  basins,  it  is  desirable  to  eliminate  their  con- 
struction if  possible.  In  many  cities  such  a  basin  is  built  in 


Fig.  90 

connection  with  each  inlet,  but  it  is  manifestly  possible  to  bring 
the  two  inlets  at  each  corner  into  one  basin,  as  in  Fig.  91,  and 
this  economical  plan  would  reach  its  logical  limit  by  having  one 
basin  into  which  all  the  inlets  should  discharge,  as  in  Fig.  90  or 
Fig.  92.  Many  engineers  to-day  believe  that  with  sewers  of 
good  grades,  discharging  freely  into  deep  water,  the  basins  are 
unnecessary,  and  that  any  material  passing  through  the  inlet 
grating  will  readily  be  carried  to  the  outlet.  Where  the  velocity 
of  the  sewage  is  less  than  2  feet  per  second,  or  where  a  light- 
grade  sewer  succeeds  a  steep-grade  gutter,  so  that  the  velocity  is 


CATCH-BASINS 


j 

1                                    1 

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~^i 

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/   A 

\\mm\c 

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O'    O 

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WM1 

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Fig.  91 


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iifl- 


Fig.  92 


Il6  SEWER  CONSTRUCTION 

much  diminished,  or  if  in  the  same  sewer  itself  a  steep  grade 
precedes  a  light  one,  a  catch-basin  is  desirable  to  prevent  deposits 
of  silt  in  the  sewer.  When  the  inlets  are  from  dirt  or  macadam 
streets,  catch-basins  should  be  provided. 

The  size  of  the  basin  or  pit  is  determined  by  the  condition  of 
the  surface  drained  and  by  the  frequency  of  cleaning  both 
streets  and  basins.  If  the  pavement  on  the  street  drained  is 
brick  or  asphalt,  the  pit  need  not  contain  more  than  two  or  three 
cubic  feet.  If  the  street  surface  is  macadam,  it  should  be  of 
twice  that  size.  It  is  better  to  have  basins  cleaned  frequently 
to  avoid  the  accumulation  of  decaying  organic  matter,  and, 
therefore,  too  large  a  basin  is  objectionable.  When  the  basin 
is  too  small,  on  the  other  hand,  it  may  fill  up  in  the  first  rain, 
and,  if  not  at  once  cleaned  out,  become  perfectly  useless. 

The  author  believes  that  basins  should  be  avoided  when 
possible,  but  that  the  conditions  of  grades  and  street  surface 
may  sometimes  require  them,  and  that  old  sewers,  or  sewers 
badly  designed  or  laid,  may  make  the  construction  of  basins 
imperative  to  prevent  filling  up  the  sewer. 

Gratings  to  hold  back  floating  matter  can  generally  be  bought 
of  any  local  foundry,  although  the  forms  of  casting  will  differ 
materially. 


Fig.  93 

Fig.  93  shows  a  rectangular  flat-top  grating  manufactured  by  a 
foundry  in  Dayton,  Ohio;  94  shows  a  circular  flat-top  grating  made 
by  a  foundry  in  South  Bend,  Ind.;  and  Fig.  95  a  circular  elevated 
top;  in  fact,  these  gratings  are  formed  of  every  conceivable  design 


CATCH-BASINS 


117 


or  pattern.  It  may  be  safely  said,  however,  that  in  spite  of 
the  large  number  of  these  gratings  on  the  market,  such  hori- 
zontal openings  will  inevitably  become  clogged,  since  leaves, 
paper,  sticks,  etc.,  which  are  arrested  on  the  grating,  soon  form 
an  impenetrable  coating,  and  the  gutter  water  then  flows  over  the 
grating.  There  should,  therefore,  unless  the  inlet  is  in  the 


Fig.  94 


Fig-  95 

center  of  the  street,  be  a  vertical  opening  into  the  curb.  The 
horizontal  grating  may  be  retained  or  not.  Fig.  96  shows  a 
horizontal  grating  and  vertical  opening,  furnished  by  a  foundry 
in  Cleveland.  Fig.  97  shows  the  casting  by  itself.  Fig.  98 
shows  the  opening  arranged  for  a  corner  inlet  instead  of  at  the 


n8 


SEWER  CONSTRUCTION 


middle  of  the  block.  Fig.  99  shows  another  design,  for  straight 
curb.  Frequently  f-inch  rods  fastened  into  the  stone  curb 
are  used  satisfactorily.  About  a  2-inch  opening  seems  to 


Fig.  96 


Fig.  97 

be  the  approved  spacing  of  the  grating  bars.  The  size 
of  the  grating  varies  from  about  20  inches  in  diameter  to 
20  X  30  inches  rectangular.  The  vertical  opening  is  commonly 


CATCH-BASINS  1 19 

about  6  inches  high,  by  from  12  to  24  inches  wide.  On  steep 
grades  the  grating  may  be  carried  into  a  recess  in  the  curb,  or 
the  opening  may  be  depressed  below  the  gutter  to  induce  the 
flow  to  enter,  otherwise  the  velocity  of  the  water  may  cause  it 
to  shoot  by. 


Fig.  98 


Fig.  99 

Traps  have  been  built  into  catch-basins  with  a  view  to  avoid 
the  escape  of  gases  from  the  sewer,  but  opinion  is  much  divided 
as  to  their  necessity.  Folwell,  for  example,  holds  that  the  inlet 
to  a  storm  sewer  should  be  without  traps,  so  as  to  assist  in  venti- 


120 


SEWER   CONSTRUCTION 


lating  the  sewer,  but  the  test  of  present-day  practice  is  that  they 
are  generally  used. 

The  avowed  purpose  of  the  trap  is  to  prevent  the  escape  of 
noisome  gases  generated  in  the  sewer.  But  such  formation  of 
gas  does  not  or  should  not  occur,  and  the  trap  really  remains 
as  an  evidence  of  the  time  when  sewers  were  elongated  cess- 
pools, and  had  to  be  cleaned  out  with  shovels.  The  smell  some- 
times detected  from  a  catch-basin  is  due  generally  to  the  organic 


Fig-  ioo 

decay  in  the  basin  itself,  and  not  to  any  gases  rising  from  the 
sewer.  Where  a  proper  velocity  is  maintained  in  a  sewer  there 
is  no  opportunity  for  deposits  to  form  nor  for  decomposition  to 
take  place,  and  therefore,  no  gases  being  generated,  the  purpose 
of  the  trap  is  defeated.  It  would  be  equally  necessary  to  trap 
the  openings  in  manhole  covers  if  traps  were  necessary  at  storm 
inlets.  There  is,  however,  a  function  of  the  trap  which  has 
value,  namely,  its  power  of  holding  back  floating  material,  such 
as  paper,  sticks,  banana  skins,  etc.  The  advantage  is  lost, 
however,  in  the  mind  of  the  author,  by  the  obstruction  which  is 


CATCH-BASINS 


121 


introduced  into  the  flow  of  the  water,  the  fundamental  axiom  to 
keep  everything  moving  in  an  unobstructed  waterway  to  the 
outfall,  being  violated.  Traps  are  used,  however,  in  a  num- 
ber of  cities.  Folwell  found,  out  of  43  cities,  26  with  traps  on 
all  connections,  14  with  traps  on  important  connections,  and 
only  3  with  no  traps  at  all.  In  view  of  such  general  practice, 
the  elimination  of  the  traps  ought  to  be  carefully  studied  in  the 
light  of  a  complete  examination  of  the  sewers  themselves. 


Fig.  101 

There  are  three  general  types  of  traps,  viz.: 

(i)  A  pipe  trap  formed  by  an  elbow  or  special,  in  continu- 
ation of  the  basin  outlet  pipe,  as  shown  in  Fig.  100,  forms  the 
simplest  trap.  Here  there  is  an  elbow  of  the  1 2-inch  pipe  used, 
which  is  built  into  the  brick  wall  and  cemented  into  the  main  pipe. 


122 


SEWER  CONSTRUCTION 


To  remove  any  possible  obstruction  under  the  elbow,  a  work- 
man must  reach  down  under  the  water,  or  must  pump  out  the 
basin  from  the  top,  or  else  there  must  be  provided  an  elbow, 
with  a  clean-out,  as  is  shown  here.  This  represents  the  type 
in  use  at  Columbus,  Ohio,  and  gives  satisfaction. 

Fig.  101  (Baumeister)  shows  a  special  tile  trap,  which  is  used  in 
Providence,  R.I.  There  is  an  improvement  over  Fig.  100,  in 
that  the  space  in  the  basin  is  not  so  encroached  upon,  but  there  is 
no  way  of  cleaning  out  the  trap  nor  of  removing  the  trap  from 
the  brickwork.  The  section  also  shows  in  detail  the  method  of 
placing  the  stonework,  and  of  forming  the  inlet. 

Fig.  1 02  shows  this  type  of  construction  carried  to  the  extreme, 
where  the  trap  has  been  reduced  in  size  until  it  is  compressed  into 


Fig.  102 

the  thickness  of  the  wall,  forming  an  integral  part  of  it.  No 
provision  is  made,  whatever,  for  cleaning  the  trap,  but  the  basin 
is  free  from  any  obstruction.  This  is  used  at  Margate,  England. 
Fig.  103  shows  a  basin  used  at  Michigan  City,  Ind.,1  where 
the  trap  has  been  removed  from  the  basin  entirely.  The  con- 

1  Paving,  Vol.  20,  p.  10. 


CATCH-BASINS 


123 


struction  is  ingenious  —  a  24-inch  tile  sewer  on  end,  the  8-inch  Y 
forming  the  outlet.  A  concave  bottom  is  formed  in  concrete 
and  a  cast-iron  cover  is  supported  on  brickwork.  The  chief 
advantage,  however,  of  this  type,  is  its  economy. 

(2)  A  cast-iron  hood,  protecting  the  end  of  the  basin  outlet 
pipe,  so  arranged  that  it  can  be  removed  for  cleaning,  is  the  next 
type.  This  is  the  simplest  and  best  trap  if  one  must  be  built, 


Fig.  103 

since  it  leaves  the  entire  catch-basin  available  for  deposit,  and 
does  not  restrict  the  area  at  times  of  cleaning. 

Fig.  104  shows  the  trap  used  in  Boston  as  made  by  one  of  the 
Boston  foundries.  When  the  hood  is  down,  the  sides  form  a  joint 
sufficiently  tight  to  enable  the  trap  to  hold  back,  or  at  least 
restrain,  the  escaping  gases,  so  that  they  are  not  objectionable. 
When  cleaning  is  necessary  the  hood  is  lifted,  hung  on  the  hook 
provided,  and  rods  may  be  forced  directly  down  the  sewer. 


124 


SEWER  CONSTRUCTION 


Fig.  105  shows  the  catch-basin  in  use  at  Wilmington,  Del.  This 
is  made  of  brick,  circular  in  plan,  2  feet  8  inches  in  diameter, 
and  8  feet  8  inches  deep.  A  cast-iron  hood  which  is  hooked  on 
over  projections  left  for  the  purpose,  serves  for  the  trap.  Inside 


Fig.  104 


the  basin  is  a  bucket,  2  feet  5  inches  in  diameter,  which  can  be 
lifted  out  with  its  contents  and  the  basin  thus  cleaned  at  one 
operation.  The  bucket  is  made  of  heavy  oak  staves,  very  sub- 
stantially, and  a  windlass  is  used  to  raise  it  to  the  sidewalk. 


CATCH-BASINS 


125 


(3)  A  division  wall  in  the  basin  built  from  the  top  down  to 
about  6  inches  below  the  water  level,  making  the  trap  an  integral 
part  of  the  basin,  constitutes  the  third  type.  This  is.  a  clumsy 
arrangement,  making  the  basin  unduly  large,  making  cleaning 


Fig.  105 

difficult,  and  increasing  the  cost,  both  of  construction  and  main- 
tenance. 

The  following  example  may,  however,  be  given  of  this  form  of 
construction.  Fig.  106  shows  the  elaborate  basin  at  Peoria,1  as 
designed  by  Mr.  Parmley.  This  basin  is  6  feet  long,  2  feet  wide, 

1  Eng.  News,  Vol.  34,  p.  432. 


126 


SEWER   CONSTRUCTION 


Fig.  1 06 


&*#2&y*          .  -•       U    U    U   U    U   LJ   U..U    U  U  U   U   LJ    U   U 

'.->&;&:\h:-'  '"s-  -'-.-.  '..     <  "      '    '    '    "  ^11 


Fig.  107 


CATCH-BASINS 


127 


and  3  feet  deep.  It  has  two  interior  gratings  as  shown,  so  that 
no  floating  or  suspended  matter  larger  than  the  screen  space  can 
pass  to  the  sewer.  A  clean-out  is  provided  for  the  apparent 
purpose  of  admitting  the  retained  silt  to  the  sewer,  but  a  gravel 


Fig.  1 08 

filter  allows  the  water  to  escape,  after  which  the  silt,  etc.,  is 
shoveled  out. 

Fig.  107  shows  a  similar  construction  used  at  Burlington,  Iowa. 
As  in  the  preceding  figure,  no  trap  is  shown  because  the  lip  of 


128 


SEWER  CONSTRUCTION 


the  trap  is  made  a  grating,  but  the  principle  in  each  case  is  that 
of  a  trap.     In  both  of  these  cases,  the  facility  with  which  the 


Fig.  109 

basins,  on  account  of  their  size,  can  be  cleaned  out,  is  probably 
not  the  least  of  their  advantages. 

Fig.  108  shows  the  old  standard  type  used  in  Philadelphia. 


CATCH-BASINS 


129 


The  plan  of  the  basin  shows  two  intersecting  cylinders,  one  that 
part  of  the  basin  carrying  the  cover,  and  the  other  the  trap  part. 


Fig.  1 10 

To  avoid  carrying  up  both  cylinders  to  the  surface,  the  cylinder 
containing  the  trap  is  arched  over  against  the  other,  involving 
some  elaborate  forms  and  masonry.  The  trap  wall  is  a  slab  of 


130 


SEWER   CONSTRUCTION 


bluestone  set  on  edge  in  the  brick  walls,  and  projecting  about 
3  inches  below  the  water  level. 

Fig.  109  shows  the  plain  and  substantial  catch-basin  built  in 
Washington.  It  is  about  4  feet  long,  4  feet  deep,  and  2  feet  wide, 
containing  a  little  more  than  a  cubic  yard.  The  trap  is  formed 
by  supporting  one  wall  on  a  stone  sill  about  5  inches  below  the 
water  level.  It  is  necessary  in  both  these  last  to  pump  out  the 
basin  to  remove  any  obstruction  beyond  the  trap. 

Fig.  no  shows  a  catch-basin  used  at  Louisville,  which  is  a 
combination  of  types  (i)  and  (3).  AT  pipe  is  used,  the 
vertical  pipe  forming  the  trap.  In  addition  there  is  a  stone  slab 
set  vertical,  its  lower  edge  flush  with  the  bottom  of  the  pipe.  To 
prevent  any  disturbance  to  the  brick  floor  a  false  bottom  of  2-inch 
oak  plank  is  laid  down. 

If  no  pits  or  traps  are  deemed  necessary,  then  an  inlet,  so  called, 
is  alone  needed.  The  simplest  way  of  accomplishing  this  is 


'  •  . 


• 

.    , 

"•«  •  ^Ztetifr 


Fig.  in 


shown  in  Fig.  in,  as  used  in  Warsaw,  N.Y.  The  curb  is  of 
stone,  but  the  rest  of  the  masonry  shown  is  brick  and  concrete, 
all  surrounding  the  end  of  the  sewer  pipe  and  directing  the  flow 
of  the  gutter  into  the  sewer. 


CATCH-BASINS 


Fig.  112  shows  a  similar  construction  for  Tarrytown,  where  a 
T  pipe  is  used  at  some  depth  below  the  surface  of  the  ground. 
The  author  believes  that  with  a  go-degree  bend,  substituted  for 
the  T  pipe,  and  then  enlarged  to  the  size  necessary  to  fit  the 


Fig.  112 

bottom  of  the  inlet  casting,  an  ideal  inlet  connection  would  be 
made. 

In  the  construction  of  catch-basins,  brick,  stone,  and  con- 
crete have  been  used.  Brick  was  used  in  curved  forms  like 
those  at  Philadelphia  on  account  of  the  ease  of  working,  but 
because  of  the  porosity  of  ordinary  brick  and  their  behavior 


132  SEWER  CONSTRUCTION 

under  frost,  they  are  not  now  generally  considered  good  mate- 
rial. Their  porosity  also  permits  leakage  through  the  walls 
of  the  basin,  which  is  not  desirable.  The  trap,  to  be  effective, 
requires  that  the  water  level  be  constantly  maintained,  and  if 
the  basin  leaks,  this  cannot  be  done. 

In  Fig.  no,  the  drawing  indicates  the  special  requirements  at 
Louisville  in  the  matter  of  interior  layers  of  cement  plaster.  It 
is  generally  specified  that  the  basins  shall  be  plastered,  one- 
half  inch  thick,  inside  and  out,  to  prevent  leakage,  and  some- 
times tar  or  asphalt  is  used. 

Concrete  is  the  cheapest  material  of  which  to  construct  catch- 
basins,  and,  except  for  the  matter  of  perviousness,  is  entirely 
satisfactory. 

In  the  matter  of  cleaning  catch-basins,  each  city  is  a  law 
unto  itself.  Folwell  thinks  that  every  catch-basin  should  be 
cleaned  after  every  rainfall.  This  may  be  ideal,  but  seems 
entirely  impracticable.  For  example,  one  of  the  New  England 
cities  has  600  catch-basins,  so  that  if  one  gang  of  three  men  and 
a  one-horse  cart  cleaned  six  basins  a  day,  it  would  take  100 
days  to  cover  the  city,  or,  the  gang  would  reach  each  basin  3 
times  a  year.  As  a  matter  of  fact,  in  this  city  the  basins  were 
cleaned  on  an  average  of  1.84  times  per  year,  and  that  in  a  New 
England  city,  where  municipal  housekeeping  is  acknowledged  to 
be  carefully  looked  after.  It  follows  that  in  this  city,  and  in 
others  under  similar  conditions,  the  basins  must  soon  become 
filled  to  their  capacity,  and  then  further  amounts  of  sediment 
are  carried  over  into  the  sewer,  and  the  inference  is  that  the 
retention  of  a  small  portion  only  of  the  sediment  in  the  basin 
is  not  worth  while.  It  is  cheaper  to  dig  out  the  sediment  when 
brought  together  to  one  large  sedimentation  basin  at  the  outlet 
if  it  has  to  be  dug  out,  than  to  collect  it  from  hundreds  of  small 
receptacles.  In  severe  winters  trouble  is  had  from  the  forma- 
tion of  ice  on  the  water  in  the  basin.  A  movable  boiler  is  used 
to  furnish  steam  by  which  the  basins  are  restored  to  usefulness. 
11  below  ground  and  untrapped,  no  trouble  need  be  feared 
except  in  extreme  weather. 


CHAPTER   IX. 
SIPHONS. 

IN  laying  out  the  lines  of  pipe  through  a  town,  it  is  often 
convenient,  in  order  to  avoid  excessive  cuttings,  to  arrange  a 
portion  of  the  pipe  line  to  act  as  a  siphon.  For  this  purpose, 
the  line  must  be  air-tight,  and  therefore  either  of  wrought  iron  or 
of  cast  iron.  Precautions  must  be  taken  to  prevent  the  siphon 
emptying  itself,  and  so  having  to  be  primed  and  started  fre- 
quently. Some  automatic  device  for  freeing  the  siphon  of  air  is 
of  great  help  in  maintaining  a  constant  flow,  since  the  entrained 
air  collecting  at  the  highest  point  will  gradually  reduce  the  flow 
until  it  stops  altogether.  An  excellent  example  of  the  use  of  a 
true  siphon  is  found  at  Norfolk,  Va.,  the  siphon  having  been 
designed  by  the  late  Colonel  Waring,  and  installed  and  operated 
by  the  city  engineer,  Mr.  W.  T.  Brooke.  The  illustration,  Fig.  113, 
shows  the  arrangement.  The  main  on  Brewer  Street,  18  inches 
in  diameter,  was  so  designed  that  for  a  distance  of  about  half  a 
mile  the  pipe  was  from  16  to  19  feet  deep.  The  soil  was  a 
quicksand,  very  troublesome  and  expensive  for  such  work.  A 
large  brick  building  on  the  narrow  street  was  additional  cause 
for  avoiding,  if  possible,  the  deep  trenching  in  quicksand. 
Colonel  Waring  recommended  the  use  of  a  siphon  of  14-inch 
cast-iron  pipe,  its  intake  at  the  bottom  of  a  manhole  at  the 
upper  end,  and  its  outlet  into  a  manhole  at  the  lower  end.  To 
prevent  unsealing  of  the  siphon  the  lower  end  was  provided 
with  a  return  bend  which  overflowed  at  a  point  5  inches 
higher  than  the  intake  end,  insuring  a  5-inch  seal  on  the 
siphon.  The  summit  of  the  siphon  is  connected  by  a  2-inch 
pipe  with  an  air-pump  so  that  accumulations  of  air  may  be 
readily  removed.  It  is  said  that  this  pump  has  to  be  worked  a 

133 


134 


SEWER   CONSTRUCTION 


SIPHONS  135 

few  minutes  every  day  to  remove  bubbles  of  air,  but  otherwise 
the  success  of  the  design  is  unquestionable. 

About  the  same  time  that  the  Norfolk  siphon  was  installed, 
an  engineer  of  Breslau,  Germany,  designed  and  built  a  similar 
pipe  line  to  carry  the  sewage  from  an  island  forming  part  of  the 
city  of  Breslau.  The  population  was  about  2000,  and  inas- 
much as  the  channels  on  both  sides  of  the  island  were  wide  and 
deep,  it  was  decided  to  use  a  direct  siphon  instead  of  the  usual 
submerged  pipe.  Use  was  made  of  a  bridge,  the  6-inch  sewer 
pipe  of  cast  iron  with  flanged  joints  and  rubber  packing  being 
brought  up  to  the  lower  chord  of  the  bridge  and  so  across  the 
river.  The  rise  in  the  siphon  is  10.7  feet,  and  the  distance 
between  the  manholes  at  each  end  of  the  bridge  is  375  feet. 
The  fall  or  head  available  for  working  the  siphon  is  10  inches. 
To  remove  the  entrained  air  an  automatic  air-valve  was  installed 
at  the  summit  which  acts  as  an  aspirator  through  the  agency  of 
a  small  stream  of  water  from  the  city  supply.  It  is  entirely 
automatic,  the  water  being  turned  on  by  a  float  in  the  air 
chamber.  The  usual  conditions  required  the  city  water  to  flow 
(under  city  pressure  through  an  inch  pipe)  about  two  minutes 
at  a  time  and  five  or  six  times  in  24  hours.  It  is  said  that  the 
arrangement  is  satisfactory  and  works  without  interruption.1 

On  the  other  hand,  unless  perfectly  air-tight  pipes  are 
used,  continual  difficulty  must  be  expected.  The  Journal 
of  the  Association  of  Engineering  Societies,  November,  1900, 
describes  difficulties  due  to  air  leaking  through  a  small  i-inch 
iron  pipe  siphon  used  for  a  private  water  supply  system,  and  it 
was  not  till  a  continuous  lead  pipe  was  substituted  that  the 
troubles  ceased.  The  inference,  therefore,  is  that  while  direct 
siphons  can  be  made  to  work,  the  construction  must  be  excep- 
tionally good,  maintenance  charges  will  be  continuous,  and  their 
combined  cost  should  be  compared  with  the  cost  of  other 
methods  of  construction. 

For  crossing  gulleys  and  gorges  a  bridge  may  be  the  cheapest 
and  the  most  convenient  arrangement.  Fig.  114  shows  a  design 

1  Inst.  of  C.  E.,  Vol.  85,  p.  464. 


136 


SEWER   CONSTRUCTION 


SIPHONS  137 

of  Rudolph  Hering  for  such  a  structure  to  cross  Cascadilla  Gorge 
in  Ithaca,  N.Y.  This  bridge  was  to  be  120  feet  long,  4  feet  wide, 
and  6  feet  deep,  of  a  simple  Warren  girder  type  as  shown.  This 
was  never  built,  the  estimated  cost  being  $1500.  Instead  the  sewer 
pipe  was  carried  in  a  wooden  box  attached  to  the  upper  chord  of 
a  highway  bridge,  which  crossed  the  gorge  at  that  place.  To 
avoid  the  vibration,  which  is  the  great  objection  to  such  construc- 
tion, the  pipe  line  on  the  bridge  was  made  of  heavy  wrought-iron 
pipe  with  screw  joints.  Expansion  was  provided  for  by  fastening 
the  upper  end  firmly  in  masonry,  and  arranging  a  slip  joint  in  the 
masonry  of  the  lower  end.  This  has  been  working  satisfactorily 
for  ten  years  without  any  repairs  or  special  attention. 

Other  devices  for  crossing  a  ravine  will  readily  suggest  them- 
selves. For  example,  a  light  wooden  pony  truss  may  be  built, 
on  which  the  pipe  may  rest.  The  sewer  pipe  itself,  if  of  iron, 
may  serve  as  the  compression  member  of  a  truss  to  which  struts 
and  diagonals  may  be  attached.  Since,  however,  it  is  customary 
to  box  in  the  sewer  pipe  on  account  of  frost,  this  last  method 
would  answer  only  in  the  south.  Finally,  the  sides  of  the  box, 
which  would  naturally  be  of  2-inch  plank,  may  be  made  the 
upper  chord  of  a  truss,  the  floor  of  the  box  being  laid  on  a  plat- 
form hung  between  the  two  chords.  This  method  is  undoubt- 
edly the  cheapest  for  short  spans.  For  protection  against  frost, 
the  sewer  should  be  surrounded  with  about  six  inches  of  some 
non-conducting  material  like  sawdust,  tan  bark,  or  straw. 
Mineral  wool  is  a  highly  desirable  non-conductor,  and  has  the 
additional  advantages  of  neither  decaying  nor  rotting  like  saw- 
dust, nor  settling  to  the  bottom  of  the  box  as  other  material  is 
likely  to  do.  The  sides  of  the  box  ought  to  be  carefully  pro- 
tected from  the  weather,  a  J-inch  tongue  and  grooved  sheathing 
on  the  outside  of  the  box  being  a  common  arrangement.  A  tin 
roof  is  desirable  as  a  further  protection. 

If  the  pipe  line  is  carried  down  one  side  of  the  valley,  across, 
and  up  the  other  side,  there  is  formed  what  is  known  as  an 
"inverted  siphon,"  though  there  is  nothing  present  involving  the 
principle  of  the  siphon.  The  pipe  in  the  bottom  of  the  valley  is 


138 


SEWER   CONSTRUCTION 


merely  working  under  pressure,  and  the  flow  will  always  take 
place,  provided  the  outlet  end  is  lower  than  the  inlet  end.  On 
account  of  the  pressure  it  is  usual  to  construct  the  siphon  of  either 
cast  or  wrought  iron,  although  wood  and  concrete  have  been 
used.  Several  accessories  are  common,  viz.,  an  overflow  at  the 
inlet  end  to  discharge  the  sewage  into  the  stream  if  the  siphon 
becomes  clogged;  an  inlet  pipe  to  admit  water  from  the  stream 


Inlet 


Fig.  115 

for  flushing  purposes;  and  a  double  or  triple  system  of  pipes,  so 
that  the  variations  of  flow  may  be  taken  care  of  without  a  serious 
reduction  of  the  velocity  in  the  siphon.  It  should  be  noted  that 
since  the  sewer  in  open  channel  is  designed  to  flow  half  full,  and 
since  the  siphon  flows  full,  the  area  of  the  latter  should  be  at  most 
only  half  that  of  the  former.  Also,  since,  at  times  of  minimum 
flow,  the  velocity  becomes  much  reduced,  it  is  necessary  to  have  the 
siphon  pipe  of  even  smaller  capacity,  or  else  deposits  in  the  siphon 
may  be  expected.  It  is  advantageous,  therefore,  to  provide  either 
an  automatic  overflow,  or  else  a  second  pipe,  coming  into  use  when 
the  capacity  of  the  siphon  is  exceeded,  in  order  to  care  for  the 


SIPHONS 


139 


140  SEWER  CONSTRUCTION 

maximum  flow,  and  usually  both  are  provided.  The  following 
examples  are  cited. 

Fig.  115  shows  the  arrangement  adopted  at  Roanoke,  Va. 
Two  i2-inch  pipes  are  provided,  rising  vertically  through  the 
bottom  of  the  manhole,  one  to  a  height  of  6  inches  and  one  to  a 
height  of  14  inches  above  the  bottom.  In  this  way  the  small  flows 
are  all  taken  through  one  pipe,  and  it  is  not  until  that  pipe  becomes 
overtaxed  that  the  sewage  in  the  manhole  rises  to  the  level  of  the 
higher  pipe,  and  the  second  pipe  begins  to  flow.  The  overflow 
pipe  is  also  shown.1 

Mr.  Farnham,  City  Engineer  of  Newton,  Mass.,  referring  to 
the  maintenance  of  siphons,  says  that  in  the  course  of  operation, 
lasting  six  years,  no  emergency  has  ever  arisen  which  required 
the  opening  of  the  siphons  in  that  city.  They  have  been  scraped 
out  once  in  each  year,  but  the  amount  removed,  grease  and  sand, 
is  hardly  sufficient  to  justify  the  trouble.  He  describes  one 
siphon  as  follows: 

The  sewer  is  brick,  24  X  30  inches,  egg-shaped,  up  to  the  point 
where  it  became  necessary  to  carry  the  flow  across  the  Charles 
River.  Between  the  manholes  on  the  banks,  245  feet  apart  (see 
Fig.  116),  two  iron  pipes  were  laid,  one  6  inches  and  one  8  inches, 
each  pipe  being  provided  with  a  gate,  so  that  either  pipe,  or  both, 
can  be  used  at  will.  An  overflow  pipe  is  also  provided.  The 
horizontal  portion  of  the  siphon  is  given  a  good  grade,  and  the 
manhole  on  the  lower  end  extends  to  the  low  point,  so  that  by 
means  of  a  special  flange  casting  (not  shown)  supplied  for  the 
purpose,  access  may  be  had  to  the  siphon  pipe  for  cleaning.  A 
T  pipe  is  also  provided,  closed  with  a  valve,  but  so  arranged  that 
a  vertical  pipe  can  be  screwed  on  above  the  valve.  By  observing 
the  height  of  water  in  this  pipe,  and  comparing  with  the  water 
level  of  the  upper  manhole,  an  idea  of  the  freedom  from  obstruc- 
tion in  the  siphon  can  be  obtained.  A  flushing  pipe  not  shown 
in  the  drawing  was  also  provided.2 

Fig.  117  shows  a  siphon  used  at  New  Orleans,  by  which  the 
sewage  is  carried  under  one  of  the  drainage  canals.  Three 

1  Paving,  Vol.  6,  p.  154.  2  Paving,  Vol.  25,  p.  410. 


SIPHONS 


141 


142  SEWER  CONSTRUCTION 

sewers,  one  lo-inch,  one  1 2-inch,  and  one  1 5-inch,  meet  at 
the  upper  manhole,  while  a  1 5-inch  sewer  leads  out  from  the  lower 
manhole.  Two  lo-inch  pipes  are  provided  under  the  canal,  one 
being  3  inches  higher  than  the  other  in  the  upper  manhole.  Only 
.05  foot  fall  is  given  the  lower  pipe  in  the  length  of  the  siphon 
(92.45  feet),  an  unusually  low  gradient.  Besides  the  difference 
in  the  levels,  valves  are  provided  in  the  upper  manhole  to  direct 
the  flow  from  one  pipe  to  the  other  at  will.1 

At  Woonsocket,  R.I.,  the  main  sewer,  just  before  reaching 
the  disposal  works,  passes  under  the  Blackstone  River  by  means 
of  an  inverted  siphon.  The  main  sewer  entering  the  upper 
manhole  is  36  inches  diameter;  and  for  the  siphon  pipes,  use 
is  made  of  three  lines  of  vitrified  pipe  buried  in  concrete,  one 
8  inches,  one  12  inches,  and  one  18  inches  diameter.  Fig.  118 
shows  the  plan,  elevation,  and  the  relative  position  of  the  three 
pipes.  The  grade  of  all  three  pipes  is  6  inches  in  100  feet.  The 
sewage  at  the  upper  manhole  on  the  right  falls  into  a  sump,  and 
there  enters  one  or  more  of  the  siphon  pipes  depending  on  the 
opening  of  valves.  In  the  lower  manhole  the  sewage  rises  and 
overflows  into  the  36-inch  brick  sewer  which  is  continued.  A 
24-inch  by-pass  is  also  provided,  controlled  by  a  valve  on  the 
36-inch  pipe  just  beyond  the  by-pass.2 

Fig.  119  shows  a  combined  storm- water  and  house-sewage 
siphon  built  at  Springfield,  Mass.,  in  1900.  The  sewer  enter- 
ing the  upper  manhole  is  five  feet  in  diameter,  the  dry-weather 
flow  occupying  but  a  small  part  of  the  total  area.  To  care  for 
this  small  flow  two  lo-inch  cast-iron  pipes  were  laid,  opening 
out  of  a  sewage  basin  in  the  upper  manhole.  To  divert  the 
domestic  flow  into  this  basin  a  depression  in  the  large  sewer 
was  arranged,  a  large  flow  discharging  equally  into  that  basin 
and  into  the  storm-water  basin  by  its  side.  The  storm-water 
siphon,  a  low  oval  cross-section  5  feet  wide  by  2  feet  i  inch  high 
opens  out  of  the  storm-water  basin.  An  overflow  is  provided.8 

1  Assn.  Eng.  Soc.,  Vol.  27,  p.  211,  Figs.  9  and  n. 

2  Eng.  Rec.,  Vol.  39,  p.  251,  Fig.  i. 
8  Eng.  Rer.,  Vol.  43,  p.  551. 


SIPHONS 


143 


144 


SEWER   CONSTRUCTION 


SIPHONS 


145 


J— i  r 


in 
Hit- 


bfl 


146 


SEWER   CONSTRUCTION 


Fig.  1 20  shows  the  method  of  separating  the  dry-weather  flow 
from  the  storm  water,  in  one  of  the  siphons  of  the  New  York  City 
sewers.1  It  was  necessary  to  carry  the  sewage  from  a  5-foot 
5-inch  sewer  under  the  subway,  the  domestic  flow  being  very 
small.  A  small  curved  dam  was  built  in  the  upper  manhole, 


Fig.  i2i 

through  which  the  1 4-inch  cast-iron  pipe  for  dry- weather  flow 
was  laid.  The  storm-water  siphon  consisted  of  two  42-inch 
cast-iron  pipes,  but  to  reach  these  the  flood  had  to  overtop  the 
curved  dam.  The  1 4-inch  pipe  was  laid  between  the  two 

1  Eng.  News,  Vol.  47,  p.  239. 


SIPHONS 


147 


larger  ones  and  all  three 
bedded  in  concrete.  No 
valves  are  provided,  and 
there  is,  of  course,  no  oppor- 
tunity for  an  overflow. 

Fig.  121  shows  the  device 
designed  for  sewers  in  Ith- 
aca, N.Y.,  where  two  6-inch 
wrought-iron  pipes  incased 
in  concrete  were  used  to 
carry  a  jo-inch  sewer  under 
Cayuga  Inlet.  An  open 
cast-iron  Y  was  used  at  the 
upper  manhole,  a  piece  of 
brass  plate  being  cut  to  fit 
across  the  branch  to  divert 
the  flow  from  one  line  to 
the  other.  A  feature  of  this 
design  is  the  clean -out 
bucket  at  the  bottom  of 
the  ascending  leg  which 
was  supposed  to  collect 
sediment.  An  overflow 
and  flushing  inlet  were  pro- 
vided, as  is  shown  in  the 
figure.  This  design  was 
never  carried  out. 

In  the  construction  of  the 
sewerage  system  of  Buenos 
Ayres,  it  was  necessary  to 
carry  the  main  intercepting 
sewer,  6  feet  9  inches  diam- 
eter, under  the  Riachuelo 
River.  The  details  are 
shown  in  Fig.  122.  That  portion  under  the  river  consists  of  three 
elliptical  tubes  of  cast  iron,  surrounded  with  concrete  18  inches 


148  SEWER  CONSTRUCTION 

thick.  These  pipes  end  in  massive  abutments,  which  also 
form  the  end  of  the  main  sewer.  Between  the  pipes  and  the 
sewer  are  placed  6  30-inch  cast-iron  pipes  each  controlled  by  a 
valve,  the  arrangement  being  the  same  at  each  end.  The  tubes 
are  5  feet  high  by  2  feet  3  inches  wide,  so  that  they  can  readily 
be  cleaned  out  by  hand.  An  interesting  detail  of  construction 
is  that  in  the  concrete  between  the  .tubes  were  embedded 
lattice  girders  computed  to  carry  the  entire  weight  of  tubes  and 
concrete  from  one  abutment  to  the  other,  a  distance  of  52  feet. 

On  account  of  delay  in  the  construction  of  the  permanent 
inverted  siphon  at  Buenos  Ayres,  it  was  found  necessary  to 
adopt  a  temporary  method  of  crossing  the  river.  For  this 
purpose  a  direct  siphon  was  used.  Four  wrought-iron  pipes, 
1 8  inches  diameter,  were  carried  across  the  river  on  a  light 
wooden  bridge  constructed  for  the  purpose.  A  circular  well, 
12  feet  diameter,  was  sunk  on  the  northern  bank  of  the  river, 
and  one  7  feet  diameter  on  the  southern  bank,  the  two  ends  of 
the  siphon  dipping  into  these  two  wells.  The  siphon  was 
started  by  filling  it  with  water  from  the  city  mains  (by  means  of 
temporary  valves).  The  siphon  being  started,  the  air  which 
accumulated  was  expelled  once  a  day  through  a  chamber  acted 
on  by  running  water  from  the  city  mains.  This  siphon  was 
368  feet  in  length,  the  head  available  to  work  the  siphon  being 
1 8  inches.  It  is  said  to  have  worked  well  and  without  a  single 
interruption  for  two  years.1 

In  the  construction  of  the  i3~mile  outfall  sewer,  of  Los 
Angeles,  two  inverted  siphons  became  necessary  on  account  of 
the  intermediate  topography.  They  are  both  built  of  wooden 
staves,  one  38  inches,  one  36  inches  diameter,  and  are  each  about 
3  miles  long.  There  is  little  that  requires  comment  in  the  con- 
struction. The  sewers  outside  of  the  siphon  are  brick,  40  inches 
diameter,  and  a  sand  pit  is  built  in  the  manhole  at  the  upper 
end  of  each  siphon  to  arrest  the  sand  which  might  otherwise  be 
carried  into  the  siphon  and  cause  trouble.  These  were  not 
satisfactory  in  that  they  caught  too  much  sand,  and  the  engineer 

1  Inst.  C.  E.,  Vol.  124,  p.  37. 


SIPHONS 


149 


has  recommended  that  they  be  cut  out,  trusting  that  the  sand 
will  be  carried  through  the  siphon  and  not  deposited.  The 
most  interesting  feature  of  these  siphons  is  the  opportunity 
furnished  for  anaerobic  bacterial  action,  and  the  effect  of  the 
gases  produced  thereby  on  the  brickwork  of  the  sewer  is  a  matter 
deserving  serious  consideration. 

Fig.  123  shows  a  very  simple  type  of  siphon,  as  built  at  Provi- 
dence, R.I.1     A  68-inch  brick  sewer  passes  under  the  Woonasqua- 


Fig.  123 

tucket  River,  changing  to  a  4O-inch  circular  pipe,  and  then  rising 
into  a  yo-inch  sewer.  No  accessories  of  any  sort  are  provided, 
except  that  there  is  a  20-inch  overflow. 

Summary.  It  may  be  well  to  repeat  the  variations  in  design 
exemplified  by  the  figures  given.  There  are  five  different  methods 
of  managing  the  variations  in  flow. 

First.  As  at  Roanoke,  Fig.  115,  by  having  the  vertical  legs  of 
descending  pipes  of  different  lengths,  so  that  one  only  will  work 
with  a  low  flow. 

1  City  Report,  1893. 


ISO 


SEWER   CONSTRUCTION 


Fie. 124 


SIPHONS  151 

Second.  As  in  Ithaca,  Fig.  121,  by  having  an  open  Y-pipe  at 
the  inlet  so  that  by  a  low  dam  the  sewage  may  be  deflected  into 
one  or  the  other  for  low  flows,  and  may  overflow  the  dam  in  times 
of  high  flow. 

Third.  As  in  Woonsocket,  Fig.  118,  by  providing  valves  at  the 
entrance  of  a  number  of  horizontal  lines  so  that  one  or  more  may 
be  brought  into  use  as  desired. 

Fourth.  As  in  Springfield,  Fig.  119,  by  forming  a  depressed 
channel  in  the  main  sewer,  through  which  the  minimum  flow  can 
be  led  away  into  a  small  pipe,  any  excess  continuing  through  a 
larger  siphon  pipe. 

Fifth.  As  in  New  York,  Fig.  120,  by  building  a  dam  in  the 
main  sewer,  through  which  a  small  pipe  is  led  to  care  for  the  low 
flow.  The  excess  overflows  this  low  dam  and  enters  the  larger 
pipe  or  pipes. 

Another  point  to  be  noted  is  that  in  some  of  the  designs,  as  at 
Springfield  and  Woonsocket,  sump-holes  are  built,  apparently 
inviting  sedimentation,  whereas  in  Roanoke  and  in  Newton,  the 
inlet  pipes  are  so  arranged  that  no  sedimentation  can  occur. 
The  only  advantage  of  the  sump  is  that  by  pumping  it  out,  access 
may  be  had  to  the  horizontal  line  of  the  siphon,  an  impossibility 
in  the  Roanoke  design. 

In  building  the  Ithaca  siphon,  Fig.  121,  the  inlet  end  was 
modified  so  that  the  manhole  was  brought  down  to  the  horizontal 
line  of  the  siphon,  and  a  clean-out  provided,  as  shown  in  Fig.  124. 
A  similar  manhole  at  the  outlet  end  made  it  possible  to  run  clean- 
out  rods  directly  from  one  side  of  the  stream  to  the  other,  and 
thoroughly  brush  out  the  pipe. 

Nearly  all  of  the  designs  provide  for  an  overflow  pipe,  through 
which  the  sewage  can  be  discharged  if  the  siphon  becomes  stopped 
up,  or  if  repairs  are  necessary,  and  this  would  seem  to  be  a  wise 
precaution  wherever  possible. 

A  flushing  gate  is  also  a  wise  addition  if  the  level  of  the  water 
in  the  stream  makes  it  possible.  It  will  then  be  easy  occasionally 
to  run  clean  water  through  the  siphon  pipes,  and  thus  wash  out 
any  sediment  which  may  have  accumulated.  The  author  has 


152  SEWER  CONSTRUCTION 

seen  a  design,  never  built,  where  automatically  such  a  flush  of 
clean  water  was  provided  whenever  any  one  of  the  several  pipes 
making  up  the  siphon  stopped  running  on  account  of  a  decrease 
of  flow  in  the  sewer.  The  idea  was  evidently  to  wash  out  the 
matter  in  suspension  before  the  stagnant  sewage  had  an  oppor- 
tunity to  deposit  it  in  the  horizontal  part  of  the  siphon. 


CHAPTER   X. 
SCREENS. 

SCREENS  play  an  important  part  in  the  process  of  sewage  purifi- 
cation. Indeed,  they  may  be  said  to  constitute  the  first  or 
primary  step  in  the  process.  Their  function  is  to  arrest  and  hold 
back  the  coarse  material  which  is  naturally  brought  down  in  the 
sewage  flow,  such  as  undigested  paper,  rags,  corks,  sticks,  leaves, 
and  similar  material,  which  is  not  offensive  in  itself,  and  which 
may  therefore  be  removed  before  the  disposal  plant  proper  is 
reached.  For  example,  on  filter  beds  or  contact  beds,  the  forma- 
tion of  a  surface  coating  is  to  be  avoided  on  account  of  its  action 
as  an  air-tight  blanket,  and  a  preliminary  screening  is  of  great 
service  in  this  regard.  Screens  are  also  to  be  used  wherever  the 
sewage  has  to  pass  through  any  moving  machinery,  such  as 
pumps,  valves,  and  siphons,  where  coarse  material  would  inter- 
fere with  the  proper  working  of  such  mechanism.  For  example, 
if  the  sewage  is  to  be  lifted  by  a  piston  pump,  screens  are  essential 
just  in  front  of  the  pump,  or  the  valves  will  be  caught  by  bits  of 
wood,  corks,  bones,  etc.,  and  the  capacity  of  the  pumps  much 
reduced.  Screens  are  also  to  be  used  in  places  where  the  admis- 
sion of  water  to  the  sewer  is  to  be  provided  for,  as  at  flushing 
inlets  or  at  storm-water  inlets,  and  where  discharge  is  made,  as 
at  the  mouth  of  the  outlets.  In  fact,  the  proper  use  of  screens  in 
sewer  construction  may  make  the  difference  between  a  system 
working  satisfactorily  and  a  system  constantly  needing  repairs  or 
overhauling. 

In  using  screens  it  must  be  remembered  that  the  solid  portion 
obstructs  the  channel  to  the  extent  of  its  area,  and  that,  besides, 
a  considerable  loss  of  head  is  introduced  by  the  frictional  resist- 
ance of  the  passages  of  the  screen.  For  example,  a  rectangular 

153 


154  SEWER  CONSTRUCTION 

screen  made  up  of  f-inch  bars,  with  f-inch  clear  spaces,  reduces 
the  area  of  free  flow  in  the  channel  by  one-half;  and  the  cross- 
section  of  the  channel,  where  the  screen  is  to  be  placed,  ought, 
therefore,  to  be  doubled,  merely  to  compensate  for  the  solid  screen 
area.  The  resistance  to  the  flow  on  account  of  the  loss  of  head 
in  passing  through  the  screen  is  not  known.  Mr.  Kuichling,  in 
a  lecture  at  Cornell  University  in  1898,  noted  the  lack  of  informa- 
tion on  this  point,  and  mentioned  his  uncertainty  in  providing 
screening  area  for  the  intake  pipe  for  the  Rochester  Water  Supply. 
In  sewage  screens  the  resistance  is  greatly  increased  by  the 
accumulation  on  the  screen  of  foreign  matter,  so  that  the  excess 
of  area  provided  is  largely  a  matter  of  maintenance;  the  larger 
the  screen  area,  the  less  labor  to  be  expended  on  cleaning,  and 
vice  versa.  Probably  a  free  area,  at  least  50  per  cent  in  excess 
of  the  area  of  the  sewer  channel,  or  a  screen  area  three  times  the 
channel  area,  should  be  provided. 

The  forms  of  screen  chamber  in  general  use  are  two  in  number. 
The  first  and  most  common  is  to  enlarge  the  cross-section  of  the 
sewer  into  a  screen  chamber,  in  which  screens  are  placed  at 
right  angles  to  the  flow.  Fig.  I25,1  shows  the  arrangement  of 
one  of  the  Boston  main  sewers,  the  area  of  the  sewer  flowing 
full  being  28  square  feet,  and  the  total  screen  area  being  56  square 
feet.  The  screens  are  made  of  f-inch  vertical  rods  with  i-inch 
clear  space  between.  These  screens  are  really  eight  screens, 
?i  X  7J  feet,  two  pairs  of  double  screens  being  provided;  one 
set  of  each  pair  is  left  in  place,  while  the  other  is  being  hoisted 
up  for  cleaning. 

Fig.  126  shows  the  Ithaca  screen  chamber,  plan  and  eleva- 
tion, similar  in  design. 

The  screen  chamber,  in  the  latter  case,  is  built  within  the  pump- 
ing station  building,  the  walls  of  which  appear  in  the  draw- 
ing. The  entering  sewer  is  3J-feet  diameter,  and  the  screen 
chamber  is  9  feet  wide  and  30  feet  long.  The  screens,  9  feet 
wide  X  8  feet  high,  are  in  duplicate  as  shown.  They  are  de- 
signed with  hoisting  apparatus,  and  a  horizontal  apron  at  the 

1  Boston  Main  Drainage,  p.  54. 


SCREENS 


155 


bottom  to  hold  and  bring  up  material  which  might  otherwise  be 
washed  off.  The  small  pipes  on  the  right  of  the  figure  lead 
directly  to  the  pumps.  Experience  with  these  screens  has 


Fig.  125 

shown  that  the  design  was  faulty  in  that  the  sudden  enlarge- 
ment of  section  from  the  sewer  into  the  chamber  caused 
deposits  in  the  corners.  It  was  necessary  to  build  a  wooden 
flume  in  the  chamber,  changing  the  section  gradually  from  the 
sewer  section  to  the  screen  section.  The  screens  were  rriade  of 


i56 


SEWER   CONSTRUCTION 


an  oak  frame,  10  feet  wide  X  8  feet  high,  the  framework  being 
made  of  2  X  6  pieces  bolted  together  at  the  corners.  The 
screen  itself  was  made  of  round  iron  f  inch  in  diameter 
fastened  to  the  frame  at  top  and  bottom  and  to  a  center 


piece  by  staple  bolts.  The  screen  was  arranged  to  drop  into 
place  between  two  wooded  strips  2X4  inches  bolted  to  the  con- 
crete walls  of  the  screen  chamber.  The  second  screen  had  a 
horizontal  extension,  reaching  from  its  top  to  the  end  wall  of 
the  chamber,  so  that  if  the  pumps  shut  down  and  the  chamber 


SCREENS  157 

filled  to  a  depth  greater  than  8  feet  the  horizontal  screen  would 
prevent  any  solid  getting  in  behind  the  vertical  screen.  No 
trouble  has  been  found  with  the  screens,  nor  has  it  been  neces- 
sary to  raise  them  from  place  in  the  twelve  years  they  have 
been  installed.  The  strength  of  the  oak  frame,  however,  has 
been  found  to  be  insufficient,  since,  with  an  accumulation  of 
debris  on  the  screen,  the  difference  of  level  of  the  sewage  has 
been  at  times  as  much  as  3  feet.  This  head  of  water  acted 
against  the  screen  as  against  a  dam,  and  the  timbers  2  inches 
thick  were  bent  and  threatened  to  break.  Braces  have  there- 
fore been  inserted  from  the  screen  to  the  back  wall  of  the  cham- 
ber to  counteract  this  unexpected  water  pressure. 

Fig.  127  shows  the  elaborate  screening  chamber  in  use  at 
Manchester,  England.  The  following  description  is  taken 
from  a  report  of  Dr.  Fowler,  and  Mr.  Wilkinson,  superintendent 
and  engineer  to  the  Manchester  Corporation,  in  1902. 

"  The  plant  consists  of  a  system  of  screens,  catchpits,  and  ele- 
vators, which  is  in  duplicate,  one  set  on  each  side  of  a  central 
storm-relief  channel.  One  set  only  is  used  when  the  flow  is 
at  its  lowest,  or  when  repairs  are  necessary.  Both  sets  of 
machinery  are  used  during  the  hours  of  heavier  flow  or  during 
storms. 

"  At  the  entrance  to  the  screening  chamber  is  a  fixed  screen 
formed  of  bars  4!  X  i  inch,  with  6-inch  space.  This  screen 
serves  to  arrest  all  large  pieces  of  timber,  etc.,  which  may  be 
carried  down  the  sewer  from  where  constructional  work  is  in 
progress,  or  any  other  large  floating  matters  which  might  tend 
to  injure  the  finer  screens.  This  screen  is  cleared  by  hand. 

"  Between  this  screen  and  the  next  is  a  cutwater  of  concrete 
cased  in  iron  plates  for  the  better  distribution  of  the  sewage 
over  the  screens  and  catchpits. 

"  The  second  screen  extends  the  whole  width  of  the  screening 
chamber,  viz.  37  feet,  but  is  formed  in  three  sections,  each  of 
which  can  be  worked  independently.  It  is  constructed  of  f-inch 
iron  bars  with  i^-inch  openings.  This  screen  is  mechanically 
cleaned  by  tines  attached  to  channel-iron  bars,  which  are  fixed 


158 


SEWER  CONSTRUCTION 


3BBBB0QQQ 
BBBQBBBBE 


30QBBBBBB 
BBBBBBBB0 


Fig.  127 


SCREENS  159 

to  endless  chains  working  on  sprocket  wheels  at  each  end  of 
the  section  of  the  screen.  As  the  chains  revolve,  the  tines  pass 
between  the  openings  in  the  screen.  The  distance  between  the 
tined  bars  is  such  that  two  of  them  traverse  the  screen  at  the 
same  time.  The  rate  of  speed  of  the  cleaning  bars  with  tines 
is  ij  feet  per  second.  The  floating  matter  arrested  by  the 
screen  is  carried  by  the  tined  bars  to  a  point  above  the  screen- 
ing-chamber floor  immediately  over  a  wrought-iron  channel. 

"  On  passing  over  the  sprocket  wheels  the  tines  recline  to  a  verti- 
cal position,  and  any  matters  which  tend  to  adhere  to  the  tines 
are  swept  off  by  means  of  a  brush  into  the  wrought-iron  chan- 
nel. The  brush  extends  the  whole  length  of  the  section  of 
screen,  and  is  fixed  on  a  shaft  actuated  by  a  lever  and  counter- 
weight for  reversing  the  motion. 

"  The  wrought-iron  channel  is  cleaned  with  a  squeegee,  and 
its  contents  loaded  into  wagons  which  pass  through  the  center 
of  the  chamber  immediately  over  the  storm-relief  channel. 

"  The  third  screen  is  very  similar  to  No.  2  (described  above), 
with  the  exception  that  the  mesh  of  the  screen  is  |-inch,  the 
bars  being  of  f-inch  metal.  The  screen  is  divided  into  four 
independent  sections." 

The  other  method  of  providing  screen  area  is  to  build  the  screen 
into  the  side  of  the  sewer,  the  length  of  the  screen  being  six  or  eight 
times  the  width  of  the  sewer,  and  then  to  build  an  adjoining 
section  or  sewer  to  intercept  the  flood  after  passing  the  screen. 

Fig.  128  shows  the  general  arrangement  as  used  at  Provi- 
dence: Here  the  sewage  is  subjected  to  a  double  screening. 
The  sewage  first  passes  through  the  filth  hoist  cages,  of  which 
there  are  four,  each  about  3  feet  wide  and  8.5  feet  high. 
They  are  semicircular  in  plan,  and  are  made  of  f-inch  steel 
rods  set  vertically  with  2  inches  spac.e  between  the  same,  the 
bottom  being  of  boiler  plate.  These  cages  slide  vertically  in 
channel  irons,  a  gate  in  front  being  shut  to  deflect  the  flow 
through  the  other  cage  when  one  is  raised  for  cleaning.  These 
cages  are  intended  to  retain  all  coarse  and  bulky  material  over 
two  inches  in  diameter. 


i6o 


SEWER   CONSTRUCTION 


The  screen  chamber  proper  is  16  feet  wide  by  69  feet  long, 
the  sewer  entering  being  8.5  feet  in  diameter.  The  screen, 
standing  at  an  angle  of  about  17  degrees  from  the  vertical,  runs 
lengthwise  about  in  the  middle  of  the  chamber.  The  screen  is 


Fig.  128 

made  of  oak  slats  10  inches  wide,  n  feet  3  inches  long,  and  i 
inch  in  thickness,  the  bronze  spacing  pieces  which  separate  the 
slats  being  J  inch  wide.  The  screen  is  kept  clean  by  men  with 
hand  rakes.  Behind  the  screens  are  the  four  inlets  to  the  pump 
wells,  each  48  inches  diameter. 

The  screens  themselves  may  be  made  in  one  of  four  ways,  viz. : 
(i)  of  a  rectangular  mesh;  (2)  of  perforated  plates;  (3)  of 
vertical  rods;  (4)  of  a  chain  or  link  combination  which  by  a 
suitable  mechanism  is  kept  in  motion  and  automatically  cleaned. 


Fig.  129 

An  example  of  the  rectangular  mesh   screen   used   at  White 
Plains  is  shown  in  Fig.  129.' 

1  Rafter  and  Baker,  p.  377. 


SCREENS 


161 


Fig.  130  shows  a  similar  screen  used  at  Marlborough.1  Both 
were  of  galvanized  iron  with  selvedge  edge,  i-inch  mesh,  and 
made  of  J-inch  (or  No.  8)  wire.  Such  a  screen  has  to  be  specially 
made,  since  the  standard  screening  is  of  lighter  wire.  The  former 
screen  is  7  feet  6  inches  X  4  feet  9  inches,  strengthened  by  the 
diagonal  tie,  as  shown,  to  allow  swinging  on  hinges  for  cleaning. 


No.2  Galvanized  Iron  Wire  Screen  with 
Selvedge  Edge  I'Slesh 


-411 


Fig.  130 

The  latter  is  4  feet  3  inches  X  2  feet  4  inches,  but  proved  to  be 
of  little  practical  value,  since  the  screen  is  placed  below  the 
precipitation  tank  beyond  which  few  solids  passed. 

A  unique  form  of  mesh  screen  was  used  at  the  Cranston,  R.I., 
outlet  (see  Fig.  13 1),2  where  the  wire  mesh  was  made  up  in  the 
form  of  a  basket  with  a  capacity  of  about  a  bushel,  the  basket 

1  Rafter  and  Baker,  p.  505.  2  Rafter  and  Baker,  p.  477. 


162 


SEWER   CONSTRUCTION 


SECTION-AB 


SCREENS 


163 


being  suspended  under  the  end  of  the  outlet  pipe  which  had  a 
free  fall.  To  clean  the  screen  it  was  only  necessary  to  take  off 
the  basket  and  turn  it  upside  down. 

At  Wayne,  Pa.,1  a  horizontal  wire-mesh  screen  was  used,  a 
loss  of  head  being  permissible.  (See  Fig.  132.)  The  screens 
first  used  had  a  mesh  2  inches  square,  but  this  was  found  to  be 


LONGITUDINAL-SECTION 


PLAN 

Fig.  132 

too  coarse  to  properly  protect  the  irrigation  area,  and  a  J-inch 
mesh  was  substituted  with  satisfactory  results.  From  a  sewage 
flow  of  one-fourth  million  gallons  about  two  barrels  of  screen- 
ings per  day  were  obtained. 

The  effects  of  a  mesh  screen  are  admirable,  but  its  disadvan- 
tage is  that  fibrous  material  clings  so  persistently  to  the  meshes 
that  it  is  difficult  to  keep  such  a  screen  clean.  A  rake  cannot 
be  used,  and  a  brush  working  only  on  the  surface  fails  to  clean 
the  wires  properly.  For  this  reason  slat  screens  are  preferred. 

1  Rafter  and  Baker,  p.  534. 


1 64  SEWER  CONSTRUCTION 

The  second  class  of  screens,  perforated  plates,  is  open  to  the 
same  objection  —  difficulty  of  cleaning  —  and  although  many 
examples  of  their  use  may  be  found  in  Europe,  there  are  very 
few  in  this  country. 

At  the  Worcester  State  Hospital  such  a  screen  is  used  at  the 
entrance  to  the  receiving  tank.  Four  brass  plates,  about  10 
feet  X  18  inches,  are  set  into  the  brick  side  walls,  each  plate 
perforated  with  60  holes  J  inch  in  diameter.  Above  the  walls 
and  over  these  plates  is  a  galvanized  wire  screen  with  J-inch 
mesh  to  intercept  the  overflow  in  times  of  flood. 

At  the  outlet  chamber  of  the  Pequannock  River  reservoir  at 
Newark,  N.J.,  a  plate  screen  is  used  in  connection  with  the 
waterworks.  Four  wells,  each  8  X  6  X  50  feet  deep,  are  built 
in  the  outlet  chamber,  two  of  which  contain  the  screens.  These 
are  built  on  steel  frames  formed  of  T  iron,  2\  X  2\  X  f,  bent 
to  form  a  square  4  feet  7  inches  on  a  side.  On  this  frame  is 
riveted  a  sheet  of  No.  18  hard  copper,  punched  with  j^-inch 
holes,  spaced  -/g  inch  apart.  The  screens  slide  in  grooves,  and 
are  raised  to  the  surface  for  cleaning  by  a  4-horsepower  gasoline 
engine  running  an  endless  sprocket  chain  to  which  the  screens 
are  attached.1 

An  English  device  employing  plate  screens  may  be  mentioned, 
which  is  the  cylindrical  screen,  consisting  of  a  hollow  cylinder 
of  sheet  metal  punched  full  of  holes  and  immersed  across  the 
channel,  which  the  screen  is  made  to  fit  tightly.  The  screen 
revolves  and  continually  presents  a  clean  surface  to  the  flow 
which  passes  across  the  cylinder.  A  brush  on  the  top  auto- 
matically keeps  the  surface  clean. 

Slat  screens  are  the  most  common,  and,  on  the  whole,  the  most 
satisfactory.  They  may  be  made  of  round  iron  or  of  flat  iron, 
and  are  usually  set  vertically  or  inclined  at  a  small  angle.  Fig.  133 
shows  the  screen  in  use  at  Ithaca,  which  has  proved  satisfactory, 
except  that  the  rods  lack  stiffness.  The  frame  of  oak'  is  so 
arranged  that  the  entire  screen  may  be  removed  from  the  chamber 
if  desired.  Ordinarily,  however,  a  rake,  so  made  that  the  teeth 

1  Eng.  Rec.,  Vol.  51,  p.  625. 


SCREENS 


I65 


Fig.  133 


166 


SEWER   CONSTRUCTION 


fit  between  the  rods,  is  ample  provision  for  keeping  the  screen 
clear.  The  unsupported  length  of  the  f -inch  rods  is  4  feet,  and 
it  has  been  found  that  in  this  distance  the  rods  are  so  flexible  that 
two  proximate  rods  may  touch,  and  the  adjacent  openings  in- 
crease to  nearly  double  the  intended  space. 


c   o    o  oj 


-a-  c 


o   o    o  o   o 


O  -6  -6-6!  o 


o-  o 


Fig.  134 

In  the  plans  for  the  Ontario  Insane  Hospital,  Colonel  Waring 
designed  a  screen  across,  an  opening  into  one  of  the  tanks  8.3  X  4. 5 
feet,  the  screen  to  be  made  of  wrought  iron,  galvanized.  The 
bars  of  the  screen  were  to  be  vertical,  of  J-inch  round  iron  spaced 
one  inch  in  the  clear;  the  height  of  the  screen,  and  apparently 
the  unsupported  length  of  the  rods,  being  4.5  feet.  The  author, 


SCREENS 


I67 


in  view  of  his  experience  with  |-inch  rods,  with  an  unsupported 
length  of  4  feet,  believes  that  the  Ontario  construction  was  too 
light. 

Sometimes  instead  of  iron  rods,  wooden  slats  are  employed, 
making  a  screen  similar  to  those  used  in  racks  for  waterpower. 
At  Providence,  for  example,1  a  wooden  screen  is  described  which 
is  placed  in  manholes  to  intercept  mill  refuse.  This  same  form 
of  screen  is  used  on  the  large  screen  chamber  shown  in  Fig.  119. 

Fig.  134  shows  the  design. 

At  Pullman,  111.,  an  elaborate  screening  tank  was  built,  a  sec- 
tion of  which  is  shown  in  Fig. 
i35.2  The  tank  is  boiler  iron 
6  feet  in  diameter  and  24  feet 
high,  the  bottom  being  set  up 
from  the  ground  high  enough 
to  allow  a  wagon  to  drive 
underneath  and  receive  the 
screenings,  which  are  allowed 
to  fall  through  a  door  in  the 
bottom  of  the  tank.  The 
screen  is  of  rectangular  mesh 
with  J-inch  openings. 

In  front  of  the  wheel  pits  of 
a  power  plant  at  Richmond, 
Va.,  is  a  fixed  screen,  with  a 
mechanical  cleaning  device 
which  merits  attention.  The 
screen  is  vertical,  made  up  of 
3!  X  f-inch  steel  bars  spaced 
if -inch  centers,  18  feet  wide 
and  21  feet  high.  In  front  of 
this  screen  is  a  movable  rake, 


Fig.  135 


supported  on  shafts  at  the  top  and  bottom  of  the  screen.  The 
cleaning  device  consists  of  a  number  of  pieces  of  angle  iron, 
fastened  to  endless  chains,  which  are  revolved  by  sprocket  wheels 

1  City  Report,  1894.  2  Rafter  and  Baker,  p.  460. 


i68 


SEWER   CONSTRUCTION 


on  the  shafting,  through  three  vertical  legs.  Riveted  to  the  hori- 
zontal leg  are  projecting  teeth,  so  spaced  that  they  fit  between 
the  bars,  just  passing  the  cross-bars  through  which  the  screen 
bars  are  fastened.  These  teeth  are  of  J  X  i-inch  iron.  Fig. 
136  shows  the  general  arrangement.1 


SECTION 


ELEVATION 


Fig.  136 


PLAN 


The  third  type  of  screens,  characterized  as  mechanical,  are 
commonly  used  in  England,  but  have  found  little  favor  in  this 
country.  Mr.  John  D.  Watson,  engineer  in  Birmingham,  has 
recently  installed  a  mechanical  screen  described  as  follows: 

The  screens  are  perforated,  flexible,  endless  metal  belts  inclined  at  an  angle 
of  30  degrees  and  running  over  a  horizontal  revolving  drum  at  each  end,  the  lower 

1  Eng.  Rec.,  Vol.  49,  p.  12. 


SCREENS 


169 


end  immersed  in  the  sewage.  The  drums  are  placed  transversely  across  the 
channel  through  which  the  sewage  is  passed,  and  are  operated  by  a  Poncelet  water 
wheel,  driven  by  the  flow  of  the  sewage,  the  speed  at  which  they  revolve  and  the 
capacity  of  the  screens  varying  with  the  changes  in  the  amount  of  sewage  flowing. 
The  intercepted  material  is  lifted  out  of  the  sewage  and  carried  around  the  drum, 
where  a  rotary  brush  cleans  it  off  and  transfers  it  to  a  worm  conveyor  placed 
transversely  in  the  rear  of  the  screens  and  discharging  in  a  barrow  or  truck  at  one 
end. 

Fig.  137  shows  dia grammatically  the  general  arrangement. 
In  conclusion  it  may  be  said  that  the  importance  of  screening 
as  the  first  step  towards  the  purification  of  sewage  is  becoming 


Fig.  137 

more  and  more  recognized.  Before  any  biological  process  can 
be  successfully  carried  on,  all  coarse  and  unresponsive  material 
must  be  eliminated;  and  while  grit  chambers  or  roughing  filters 
may  be  used,  engineers  are  appreciating  more  and  more  the 
efficiency  and  economy  of  the  use  of  screens.  At  Columbus, 
Ohio,  for  example,  the  engineer  in  charge  of  the  experimental 
plant,  after  experimenting  with  various  types  of  screens  and  size 
of  mesh,  adopted  two  screens  of  diamond  mesh  wire  cloth  woven 
with  No.  12  wire.  The  first  screen  had  a  clear  opening  of  J  inch, 
and  the  second  of  f  inch,  and  the  action  of  the  screens  was  con- 
sidered to  be  of  great  importance  as  a  part  of  the  entire  method 
of  treatment. 


CHAPTER  XL 

STORM-WATER   OVERFLOWS   AND  REGULATORS. 

IN  the  construction  of  combined  sewers,  that  is,  sewers  which 
carry  both  storm  water  and  house  drainage,  there  are  two  methods 
or  opportunities  for  reducing  the  expense  involved  in  the  con- 
struction of  large  storm  sewers:  First,  by  diverting  the  storm 
water,  in  excess  of  a  certain  amount,  from  the  trunk  sewer  into 
a  convenient  stream,  thereby  avoiding  the  first  cost  of  a  long  and 
large  trunk  sewer;  and  second,  by  diverting  the  excess  storm 
water  before  it  passes  through  a  pumping  station  or  on  to  a 
purification  bed,  thereby  avoiding  the  continual  expense  of  han- 
dling a  large  amount  of  storm  water. 

To  illustrate  a  suitable  use  of  these  storm-water  overflows, 
the  following  example  is  given:^ 

The  city  of  Rochester  has  a  long  intercepting  sewer,  surround- 
ing the  city  on  three  sides,  as  shown  in  Fig.  138.  This  sewer 
collects  a  large  part  of  the  city  sewage,  both  domestic  and  storm 
water,  and  prevents  the  contamination  of  the  small  streams 
shown.  When  this  sewer  has  reached  the  point  A,  the  diameter 
is  8  feet,  and  the  capacity  is  340  cubic  feet  per  second,  although 
the  house-sewage  flow  is  only  10  cubic  feet  per  second.  In  order 
to  avoid  the  cost  of  building  this  large  sewer  further,  it  is  reduced 
to  4  feet  in  diameter,  and  capacity  of  40  cubic  feet  per  second, 
and  provision  made  by  which  the  difference  between  40  cubic 
feet  and  340  cubic  feet  can  escape  through  a  special  channel  into 
the  waters  of  Thomas  Brook,  as  shown.  This  has  worked  well 
for  ten  years,  but  there  are  indications  that  the  overflow  comes 
into  more  frequent  use  than  was  intended,  that  the  result  is  likely 
to  be  a  nuisance  in  Thomas  Brook,  and  that  some  remedy  must 
soon  be  provided.  A  second  overflow  is  also  provided,  at  the 

170 


STORM-WATER   OVERFLOWS  AND   REGULATORS       1 71 

point  B,  under  similar  circumstances,  also  at  three  other  con- 
venient points. 

The  propriety,  from  the  sanitary  standpoint,  of  the  use  of 
this   arrangement    depends    on   the   local   conditions.      If    the 


Fig.  138 

stream  is  small,  tortuous  and  sluggish,  with  shallow  ponds, 
the  storm  overflow  should  not  be  used.  But  if  the  discharge 
is  to  be  into  a  large  river,  already  organically  polluted,  and 
thereby  unfitted  for  drinking  water,  such  a  device  is  proper 
and  economical. 
This  separation  of  sewage  from  storm  water  is  accomplished 


1/2  SEWER   CONSTRUCTION 

in  one  of  three  ways,  viz.,  by  a  so-called  leaping  weir,  by  an 
overflow  weir,  or  by  a  mechanical  regulator. 

The  leaping  weir  has  been  little  used  in  this  country,  although 
there  are  many  references  to  it  in  English  works.  It  was  first 
used  in  waterworks  at  Bradford  to  allow  highly  discolored 
waters  of  storms  to  pass  by  the  purer  water  of  other  stages. 
Baldwin  Latham  also  used  the  device  many  years  ago. 

Fig.  139  shows  the  principle  on  which  it  works,  as  well  as  its 
practical  application.  The  construction  illustrated  was  built 
in  Milwaukee,  where  it  was  necessary  to  divert  the  dry-weather 
sewage  flow  of  some  twelve  old  outlet  sewers  from  the  Menom- 
inee  River  into  the  new  intercepting  sewer,  the  storm  water 
being  allowed  to  continue  through  the  old  sewer  to  the  river. 
It  is  said  that  the  device  works  admirably  and  with  little  need 
for  repairs.1  In  general,  with  small  dry-weather  flow,  the  con- 
centrated sewage  falls  through  the  opening  into  the  intercepting 
sewer,  which  goes  to  the  pump  or  to  the  disposal  works.  In 
time  of  storm,  however,  the  width  of  opening  being  properly 
adjusted,  the  heavy  flow  leaps  the  opening  and  is  discharged 
directly  into  the  river  or  tide  water.  Moore 2  assumes  that  the 
mean  velocity  of  the  water  flowing  over  this  weir  is  expressed  by 
the  equation  V.  =  .66  \/2g  H.  He  then  computes  the  hori- 
zontal width  of  the  weir  by  assuming  that  a  particle  will  pass 
horizontally  from  A  to  B  in  /  seconds,  or,  if  the  velocity  is  F,  the 
width  AB  must  be  V.  t,  or  .66  \/2g  H  X  /.  But  the  vertical 
velocity  is  that  due  to  a  free  fall,  so  that  the  distance  AD  will  be 
by  mechanics  =  J  gt2.  From  these  two  equations  /  may  be 
eliminated  and  the  depth  expressed  in  terms  of  the  width,  as 

o    W2 

D  =  -  -  — •    This  is  for  a  definite  head,  H,  in  the  sewer,  fixed 
10    ri 

as  that  depth  when  the  weir  shall  come  into  action,  and  will 
enable  the  parabolic  path  of  the  overflow  to  be  plotted,  just  under 
which  the  weir  may  be  built  wherever  desired.  (See  Fig.  140.) 
However,  it  is  safer  to  provide  for  a  final  adjustment  by  having 

1  Eng.  News,  Vol.  30,  p.  401. 

8  Moore's  Sanitary  Engineering,  p.  72,  Fig.  49. 


STORM-WATER   OVERFLOWS  AND   REGULATORS       173 


174 


SEWER   CONSTRUCTION 


the  stone  or  iron  weir  at  the  opening  movable,  and  only  fastened 
permanently  after  the  capacity  has  been  tested. 

An  overflow  weir,  as  the  name  indicates,  provides  that  when 
the  flow  of  storm  water  has  reached  a  certain  volume,  the  excess 
shall  pass  over  a  weir  whose  height  has  been  carefully  deter- 


Fig.  140 

mined.  By  such  a  device  the  quantity  passing  to  the  disposal 
plant  can  be  restricted  to  a  certain  volume,  although  there 
must  always  be  a  certain  flow,  varying,  however,  in  concen- 
tration. Fig.  141  shows  the  overflow  weir  at  Cleveland,  Ohio.1 

A  large  sewer  14  feet  9  inches  in  diameter,  known  as  the  Wai- 
worth  Run  Sewer,  drains  about  3000  acres,  and  carries  both 

1  Eng.  Rec..  Vol.  40,  p.  60. 


STORM-WATER   OVERFLOWS  AND   REGULATORS       175 

house  sewage  and   storm  water.      To   avoid   the  discharge  of 
the   concentrated  house  sewage  into  the  Cuyahoga  River,  an 


overflow  chamber  was  built;  the  small  sewer  at  the  bottom 
of  the  figure,  5  feet  in  diameter,  leads  to  the  main  intercept- 
ing sewer,  and  any  excess  escapes  over  the  long  curved  weir 


176  SEWER  CONSTRUCTION 

into  the  outlet  sewer,  which  is  13  feet  6  inches  in  diameter.  The 
short  connecting  sewer  shown  is  a  by-pass  to  be  used  until  the 
intercepting  sewer  is  completed.  The  estimated  maximum  flow 
in  the  i4J-foot  sewer  was  2500  cubic  feet  per  second.  The 
domestic  sewage  flow  was  estimated  at  60  cubic  feet  per  second, 
the  5-foot  sewer  having  that  capacity  when  nine-tenths  full. 
The  weir  then  is  designed  to  discharge  2440  cubic  feet  per 
second  without  allowing  the  5-foot  sewer  to  flow  under  a  head. 
The  weir  sill  is  4^  feet  above  the  invert  of  the  sewer.  The 
overflow  sill  is  built  of  hard  sandstone,  and  is  secured  in  place 
by  anchor  bolts  reaching  into  the  concrete  below.  The  inverts 
of  the  sewers  are  lined  with  hard  shale  brick,  and  the  rest  of 
the  arch  built  of  softer  material. 

The  points  specially  considered  in  arranging  the  different 
details  were: 

(1)  The  weir  must  act  positively  to   prevent  internal  pres- 
sure in  the  5-foot  sewer,  or  to  prevent  any  flow  greater  than  it  is 
intended  to  carry. 

(2)  The  effect  of  the  full  flow  in  the  5-foot  sewer  must  not 
reduce   the   hydraulic   grade   or   the   predetermined    minimum 
velocity  in  the  combined  sewer. 

(3)  The  weir  must  not  become  submerged,  and  the  flow  be 
thus  checked. 

(4)  The  fall  over  the  weir  must  not  be  too  abrupt,  or  forces 
will  be  set  in  action  which  tend  to  destroy  the  masonry. 

The  article  from  which  the  figures  are  taken  gives  further 
interesting  details  of  construction. 

Fig.  I421  shows  a  similar  construction  used  at  Providence, 
R.I.,  the  diversion  in  this  case  being  to  relieve  the  overtaxing  of 
two  48-inch  cast-iron  pipes  which  carry  the  normal  effluent  out 
into  the  deep-water  channel.  The  main  twin  sewers  shown  in 
the  drawing  are  86  X  94  inches.  The  lower  of  the  two  goes 
directly  to  the  storm  outlet.  The  upper  sewer,  carrying  the 
domestic  flow,  ordinarily  extends  to  the  intercepting  sewer  (not 
shown)  through  a  pipe  70  X  76  inches,  but  when  this  becomes 

1  Prov.  Kept.,  1891. 


STORM-WATER   OVERFLOWS  AND   REGULATORS       177 

overtaxed,   the  excess  flows  over  the   curved  weir  and   to   the 
storm-water  outlet.     The  arch  construction  for  the  three  sewers 


Fig.  142 

at  the  junction  chamber  is  particularly   interesting,   the  large 
arch  having  a  span  of  20  feet. 

Fig.  143  shows  the  plan  and  section  of  the  overflow  weir  pro- 
vided at  point  A  in  the  Rochester  East  Side  Trunk  Sewer, 
above  referred  to.  The  section  on  the  right,  8  feet  diameter,  is 


SEWER  CONSTRUCTION 

the  main  sewer  before  the  reduction  in  size,  while  the  section  on 
the  left,  3  feet  diameter,  is  the  overflow  pipe. 

The  third  class  of  regulators  are  mechanical  in  action,  valves 
which  work  automatically  opening  or  shutting  with  the  rise  and 
fall  of  the  sewage. 

Fig.  144  l  shows  one  in  use  in  the  Boston  Metropolitan  System, 
by  means  of  which  the  discharge  into  the  interceptor  can  be  kept 
constant.  It  was  desired  in  this  case  to  take  from  the  main  brick 
sewers,  3  feet  6  inches  in  diameter,  a  certain  uniform  quantity, 


Fig.  143 

the  surplus  continuing  in  the  sewer.  On  account  of  the  limited 
capacity  of  the  interceptor,  a  rectangular  chamber  3  feet  6  inches 
by  6  feet  6  inches  is  entered  by  the  1 2-inch  connecting  pipe,  to 
which  is  attached  the  regulating  device.  This  consists  of  two 
copper  floats,  connected  by  a  cast-iron  beam.  Between  these 
floats,  and  attached  to  the  beam  connecting  them,  is  a  vertical 
brass  pipe  with  open  mouth,  which  slides  up  and  down  in  the 
12-inch  pipe.  As  the  floats  rise  and  fall,  the  brass  pipe  also  rises 
and  falls,  the  open  mouth  maintaining  always  the  same  submer- 
gence. By  changing  the  relative  position  of  the  brass  pipe  and 
the  floats,  a  different  quantity  can  be  discharged. 

1  Eng.  Rec.,  Vol.  40,  p.  74. 


STORM-WATER   OVERFLOWS  AND   REGULATORS       179 


ELEVATION 


1 8o 


SEWER   CONSTRUCTION 


A  different  type  used  in  Worcester,  Mass.,  is  shown  in  Fig.  145.* 
The  sewage  enters  the  manhole  from  which  an  overflow  leads  into 
the  brook.  A  special  regulator  manhole  is  built  near  by,  connected 
with  the  former  by  an  8-inch  pipe.  A  catch-basin  or  sand  pit 
2\  feet  deep  is  provided  to  eliminate  the  sand,  etc.,  which  the 
combined  sewer  brings  down.  The  regulator  is  operated  by  a 
float  resting  in  the  water  at  the  same  level  as  in  the  main  inter- 
cepting sewer.  As  that  water  rises,  the  float  rises,  exerting  a  pull 
on  the  strap  attached  to  the  end  of  the  valve,  which,  of  course, 
tends  to  close  the  valve. 


0 


Fig.  145 

Fig.  146  2  shows  a  regulating  device  used  at  Harrisburg,  Pa. 
The  problem  here  was  to  admit  to  the  intercepting  sewer  in  dry 
weather  a  certain  amount  of  creek  water,  in  order  to  increase 
the  velocity  of  flow.  In  case  of  rain,  however,  it  was  necessary 
to  shut  this  off.  There  are  two  sets  of  three  1 2-inch  vitrified  pipes 
laid  through  the  concrete  head  wall  to  serve  as  inlets  for  the 
creek  water,  one  set  four  feet  higher  than  the  other.  A  silt  basin 
20  X  8  X  12  feet  deep,  with  a  bar  grate,  is  introduced  for  the 
purpose  of  settling  and  screening  out  silt,  leaves,  etc.  The 
water  then  passes  through  a  rectangular  cast-iron  orifice  into 
the  regulating  chamber.  A  galvanized  iron  float  is  so  arranged 

1  Eng.  Rec.,  Vol.  44,  p.  395.  '  Eng.  Rec.,  Vol.  46,  p.  342. 


STORM-WATER   OVERFLOWS  AND   REGULATORS       181 

as  to  rise  and  fall  with  the  level  of  the  water  in  the  interceptor 
at  a  point  about  10  feet  down  stream;  connection  between  the 
well  and  this  point  is  made  by  means  of  a  4-inch  pipe.  As 


the  float  rises,  the  bell-crank  connection  with  the  sliding  valve 
causes  the  valve  to  close,  and  vice  versa.  This  connection  arm 
is  fastened  into  the  concrete  wall  of  the  chamber  by  means  of  a 
short  piece  of  angle  iron,  the  holes  for  the  anchor  bolts  being 
slotted  to  allow  of  a  vertical  adjustment.  The  attachment  to 


182 


SEWER   CONSTRUCTION 


the  arm  is  made  by  slotted  holes  on  the  horizontal  leg  of  the  angle, 
so  that  the  adjustment  for  position  may  be  exactly  made.  The 
face  of  the  valve  and  all  wearing  parts  are  made  of  bronze,  the 
rest  being  of  cast-iron. 

Fig.  147  shows  the  simple  regulator  used  on  the  Brookline 
sewers.  A  bent  arm  acts  as  a  lever,  one  end  forming  a  sliding 
gate,  which  opens  or  closes  the  exit  from  the  main  village  sewer. 
The  other  end  is  attached  to  a  float  which  moves  up  and  down  in 
a  float  chamber.  When  the  level  of  the  sewage  in  the  intercepting 
sewer  rises  to  a  point  where  it  overflows  into  the  chamber,  the 


Fig.  147 

float  is  lifted  and  the  valve  closes,  forcing  the  sewage  into  an  over- 
flow pipe  leading  out  from  a  manhole  on  the  left  (not  shown).  A 
small  drain  pipe  leads  out  from  the  chamber  so  that  as  the  level 
in  the  intercepting  sewer  falls,  the  float  descends,  opening  the  gate. 
This  device  has  worked  admirably  for  twelve  years. 

Fig.  148  shows  a  regulating  device  furnished  by  the  Coffin 
Valve  Company.  A  copper  float  moves  up  and  down  in  its 
chamber,  the  motion  being  communicated  through  a  rocker  arm 
to  a  valve  which  slides  across  the  entrance  to  the  intercepting 
sewer  as  the  float  rises.  The  cut  apparently  shows  the  outlet 
to  the  outfall,  which  then  comes  into  play,  the  inlet  not  being 


STORM-WATER   OVERFLOWS  AND   REGULATORS       183 

visible.     The  side  motion  of  this  valve  differs  markedly  from  the 
other  valves,  which  are  all  of  the  flap-valve  type. 

Fig.  149 l  shows  a  regulator  installed  at  Woburn,  Mass.,  about 
twenty  years  ago.  A  large  copper  float  rises  and  falls  in  a  well, 
built  by  the  side  of  the  manhole.  The  float  is  attached  to  a  lever 
which,  working  through  an  opening  in  the  manhole  wall,  causes 


Fig.  148 

the  flap  valve  to  open  and  shut  as  the  sewage  in  the  well  falls 
and  rises. 

The  use  of  overflows  or  regulators  is  a  relic  of  the  time  when 
storm-water  sewers  formed  the  general  type  of  sewers,  and  is 
really  a  makeshift,  to  adjust  the  undesirable  conditions  thus 
formed  to  the  modern  necessities  for  purification.  Except  for 

1  Eng.  Rec.,  Vol.  22,  p.  41. 


1 84 


SEWER   CONSTRUCTION 


the  need  of  purification,  or  for  the  construction  of  long,  inter- 
cepting sewers  to  relieve  excessive  local  pollution,  no  such  devices 
would  be  needed.  Nor  would  they  be  needed  if  house  sewage 
had  been  kept  out  of  the  storm  sewers.  It  is  not  likely  that  in 


LONGITUDINAL   SECTION 


TRANSVERSE   SECTION 


PLAN 


Fig.  149 


the  future  the  construction  of  combined  sewers  will  be  permitted 
by  the  state  sanitary  authorities,  so  that  the  devices  here  described 
will  be  limited  in  their  application  to  old  sewers  built  on  the  com- 
bined plan,  the  proportional  number  of  which  must  steadily 
decrease. 


CHAPTER    XII. 
BELL  MOUTHS. 

WHEN  sewers  are  over  three  feet  in  diameter  it  is  not  neces- 
sary to  make  bends  entirely  within  the  manhole  walls,  since  work- 
men can  readily  enter  such  sewers  and  remove  obstructions  by 
hand.  Also  the  junction  of  two  large  sewers  need  not  be  made 
within  the  manhole,  but  the  sewer  walls  can  be  brought  to  an 
intersection.  When  the  angle  between  the  axes  of  the  intersect- 
ing sewers  is  greater  than  about  30  degrees,  the  walls  are  brought 
into  each  other,  the  weight  of  the  arches,  with  their  loadings, 
being  safely  carrie^J  down  through  the  walls  of  one  of  the  two 
sewers  to  the  foundation.  For  this  construction  a  template  of 
the  line  of  intersection  of  the  inside  walls  should  be  made,  and 
the  brickwork  carefully  laid  up  to  this  on  the  main  sewer,  the 
other  being  afterward  tied  on  along  this  line.  When  the  angle 
is  less  than  about  30  degrees,  the  arch  thrust  cannot  be  taken  up, 
and  a  construction  known  as  a  bell  mouth  must  be  resorted  to. 
In  this  (and  the  same  construction  applies  when  one  sewer  is 
brought  into  the  other  in  a  curve) ,  the  side  walls  nearest  each  other 
are  stopped  where  the  springing  lines  intersect,  and  a  vertical 
wall  is  built  across  in  the  triangular  spaces  above.  Then  from 
the  outside  walls  at  the  springing  lines  a  large  cover  arch  is 
thrown  from  outside  to  outside,  the  former  small  arches  being 
omitted.  This  large  arch  is  then  gradually  reduced  in  span  in 
the  form  of  a  trumpet  until  it  coincides  with  the  arch  of  the  main 
sewer  below  the  junction.  The  object  of  this  construction  is  to 
avoid  a  reentrant  intersection  of  the  two  arches  which  would  be 
entirely  unsupported  and  unstable.  The  section  on  KK  in 
Fig.  141  shows  the  conditions,  the  intersection  of  the  arches 
evidently  introducing  unbalanced  and  unsupported  vertical 

185 


1 86 


SEWER  CONSTRUCTION 


forces.  The  dotted  lines  in  that  figure  show  the  relative  posi- 
tion of  the  enveloping  arch  which  would  be  used  in  a  bell-mouth 
construction. 

The  plan  of  the  intersecting  sewers  should  show  a  connect- 


ing  curve  even  if  the  angle  between  the  two  lines  is  as  small  as 
25  or  30  degrees.  An  ideal  intersection  will  bring  the  central 
threads  of  the  surface  flow  in  the  two  sewers  together  tangen- 
tially,  so  that  the  connecting  curve  is  always  desirable.  Such 
an  intersection,  however,  makes  the  quoin,  or  wedge-shaped 


BELL  MOUTHS  187 

masonry,  forming  the  edge  of  the  intersecting  surfaces,  too 
acute  to  be  substantially  built  of  brickwork.  It  has  therefore 
been  customary  to  replace  the  brickwork  with  a  cut  stone 
quoin,  ending  with  a  flat  top  at  the  spring-line  level.  Theo- 
retically this  quoin-stone  extends,  wedge-shaped,  from  the  point 
where  the  spring  lines  intersect  along  a  curve  to  the  point  where 
the  invert  of  the  upper  sewer  intersects  the  inner  surface  of  the 
other  sewer.  The  following  drawing  (see  Fig.  150),  prepared  by 
one  of  the  author's  students,  will  make  this  clear.  The  plan  and 
elevation  of  the  two  intersecting  sewers  were  drawn,  and  hori- 
zontal elements  of  the  two  surfaces  at  the  same  level  (bearing 
the  same  numbers  in  the  figure)  were  produced  to  an  intersec- 
tion. The  elements  of  the  lower  part  of  the  sewers  show  the 
line  of  the  quoin  referred  to,  that  is,  from  M  to  AT".  An  eleva- 
tion of  this  line  is  shown  in  detail,  and  cross-sections  at  a 
number  of  points  show  the  wedge  angle.  If  the  arch  of  the 
smaller  sewer  enters  the  larger  sewer  above  the  springing  line, 
a  reentrant  angle  referred  to  above  is  formed,  and  the  trumpet- 
shaped  arch  should  be  thrown  across  both  sewers,  i.e.,  from 
A-i  to  P-R. 

Fig.  151  shows1  the  horizontal  considerations  just  discussed 
illustrated  by  a  concrete  example.  The  main  sewer  shown  is 
known  as  the  Wingohocking  sewer  in  Philadelphia,  and  the 
intersection  is  with  a  lateral  at  the  corner  of  Eighteenth  Street 
and  Bellfield  Avenue.  Three  cross-sections  are  shown,  illus- 
trating both  the  shape  of  the  floor  intersection  and  also  the 
arch  spanning  both  sewers.  In  the  longitudinal  section  the 
heavy  line  shows  the  curve  of  invert  intersection. 

Fig.  152  shows  a  similar  construction  in  the  case  of  the  basket- 
handle  sections  used  on  the  Metropolitan  Sewerage  System  of 
Massachusetts.  The  plan  and  two  cross-sections  are  given  to 
show  the  gradual  change  in  the  line  of  division  between  the  two 
channels,  and  to  show  the  unusual  form  of  the  pointed  arch  used 
as  a  cover  arch.  The  section  showing  the  manhole,  at  the  top 
of  the  quoin,  shows  also  the  curvature  of  the  quoin  in  a  vertical 

1  Eng.  News,  Vol.  35,  p.  163. 


i88 


SEWER   CONSTRUCTION 


BELL  MOUTHS 


189 


plane.1     The  figure  also  shows  more  clearly  than  the  preceding 
one  that  the  plan  of  this  line  is  not  straight.     Only  when  the 


two  sewers  joining  are  of  the  same  size  and  elevation  would  the 
plan  be  truly  straight,  although  in  many  other  cases  the  approxi- 
mation is  very  great. 

Fig.  153  shows  another  intersection,  also  on  the  Metropolitan 

1  Eng.  News,  Vol.  31,  p.  386. 


190 


SEWER   CONSTRUCTION 


BELL  MOUTHS 


191 


system  at  Boston,  with  the  same  basket-handle  sewers,  but 
with  a  semicircular  arch  instead  of  a  pointed  arch.  The  effect 
of  the  flat  invert  and  the  vertical  side  walls  on  the  shape  of  the 
quoin  curve  may  be  clearly  seen  by  comparison  with  Figs.  150 
and  151. 

Fig.  142,  showing  the  overflow  at  Providence,  shows  also  the 
cross-section  of  the  bell-mouth  chamber  and  the  large  cover 
arch,  20  feet  in  diameter.  Fig.  154  shows  a  photograph  of  the 


Fig.  154 


same  bell  mouth  looking  up  stream  at  the  quoin,  which  on 
account  of  the  weir  is  here  made  vertical.  One  difficulty  which 
may  arise  in  this  construction  is  the  lack  of  head  room,  since 
the  large  cover  arch,  if  made  semicircular,  rises  above  the  arches 
of  the  connecting  sewers.  If  the  arch  is  flattened  as  in  Fig.  141, 
heavy  abutment  pressures  are  introduced,  and  additional 
masonry  at  extra  cost  is  required.  In  many  cases,  however, 
any  form  of  cover  arch  would  be  out  of  the  question,  and  a  sub- 
stitute must  be  found. 

Fig.  155  shows  the  alternate  construction  as  recommended  by 


SK\VER   CONSTRUCTION 


I   C    r-         '  .°  •-         V^~"__. 


Fig.  155 


BELL   MOUTHS 


193 


Mr.  E.  H.  Bowser,  of  Louisville,  Ky.1  Below  the  spring  line  the 
connection  is  made  as  before  described.  Above  the  spring 
line,  the  walls,  instead  of  being  arched  across  the  opening,  are 
built  straight  up  to  the  height  of  the  intrados  of  the  larger 
sewer.  On  top  of  these  walls  across  the  bell  mouth  I  beams  are 
laid  about  3  feet  apart,  and  the  spaces  between  the  beams  filled 
with  brick  arches  backed  with  concrete,  or  with  reinforced  con- 
crete slabs.  Mr.  Bowser  says  that  the  crowns  of  these  small 


Fig.  156 

arches  should  not  be  made  higher  than  the  crown  of  the  larger 
sewer,  although  the  reason  for  such  a  limitation  is  not  plain  to 
the  author.  Fig.  156  shows  a  sketch  drawing  to  illustrate  a 
junction  chamber  in  Minneapolis,  redrawn  from  Engineering 
News.2 

Care  must  be  taken  to  secure  good  construction,  even  with  the 
bell  mouth  carefully  designed.  There  is  danger,  otherwise,  of 
the  arch  structure  failing,  as  at  Nashville,  Tenn.,  where  the 

1  Eng.  News,  Vol.  35,  p.  163.  2  Vol.  31,  p.  268. 


194  SEWER  CONSTRUCTION 

centers  were  pulled  after  twenty-four  hours,  and  the  whole  bell 
mouth  caved  in. 

A  large  proportion  of  the  cost  of  the  bell  mouth  is  the  value  of 
the  labor  employed,  and  as  this  is  ever  increasing  it  is  likely  that 
the  construction  shown  in  Fig.  145  will  be  hereafter  the  most 
common.  With  reinforced  concrete,  a  flat  roof  of  girders  and 
slabs  can  be  substituted  for  the  I  beams  and  small  brick  arches, 
and  unless  the  sewers  flow  full,  no  advantage  belonging  to  the 
bell  mouth  is  lost.  If  the  sewer  flows  full,  the  bell  mouth  is 
the  most  satisfactory  method  of  construction,  because  thereby  the 
two  flows  are  brought  together  into  one  stream  in  a  manner  most 
free  from  disturbances. 


CHAPTER    XIII. 
FOUNDATIONS. 

IF  the  ground  through  which  a  sewer  is  to  pass  is  loam,  dry 
clay,  sand  or  gravel,  no  special  foundation  is  needed  for  the 
pipe,  even  in  the  case  of  the  largest  sewers.  The  trench  is  exca- 
vated to  subgrade,  and  trimmed,  when  possible,  to  conform  to 
the  outer  circumference  of  the  pipe,  special  excavations  being 
made  for  the  bells.  But  if  the  bottom  is  mud,  or  running  sand 
or  silt,  or  a  clay,  which,  when  wet  and  disturbed,  softens  and 
slides,  some  special  preparation  for  the  pipe  is  needed. 

The  simplest  means  of  adding  to  the  stability  of  the  pipe  line 
is  to  excavate  enough  below  the  pipe  to  place  a  wide  plank 
underneath,  butting  the  plank  at  the  end  joints,  and  nailing  on 
a  splice  piece.  It  is  best  to  have  this  plank  low  enough  so  that 
at  least  three  inches  of  gravel  or  ashes  can  be  placed  between 
the  plank  and  the  pipe  to  give  the  latter  a  good  bed,  and  avoid 
a  bearing  on  the  hubs  alone.  This  is  a  suitable  construction 
when  the  soft  material  occurs  in  pockets,  the  plank  aiding  to 
bridge  the  pocket  without  abrupt  settlement.  The  plank  should 
be  well  below  the  level  of  the  ground  water,  so  that  there  may 
be  no  decay  of  the  plank,  a  condition  which  usually  exists,  how- 
ever, when  any  artificial  foundation  is  needed.  Often  the  plank 
can  be  omitted  and  the  foundation  improved  by  extra  excavation 
and  refilling  with  gravel.  The  pressure  per  unit  area  on  the  mud 
is  thus  reduced,  and  at  the  same  time  a  good  drainage  is  provided. 
Whether  this  is  an  advisable  method  depends  on  the  weight  of 
the  pipe  and  on  the  bearing  power  of  the  soil.  If  the  width  of 
the  pressure  area  is  increased  along  45-degree  lines,  the  bearing 
area  is  increased  by  twice  the  thickness  of  the  gravel  bed,  or  a 
bed  one  foot  deep  reduces  the  unit  pressure  on  the  natural  soil  to 

'95 


196  SEWER   CONSTRUCTION 

about  one-third.  A  15 -inch  pipe  weighs,  when  half  full  of  water, 
65  +  40  =  105  pounds  per  running  foot,  and  a  24-inch  pipe 
weighs  170  4-  205  =  375  pounds  per  running  foot.  If  the  natural 
soil  will  not  hold  up  the  loads  in  either  case,  without  undue  or 
unequal  settlement,  the  gravel  bed  will  reduce  these  loads  to  35 
and  125  pounds  respectively.  The  level  of  the  ground  water 
need  not  be  considered,  and  the  cost  is  that  of  the  extra  excava- 
tion and  the  value  of  the  gravel  for  refilling. 

If  the  sewer  is  brick  or  concrete,  and  the  earth  is  soft,  or  the 
bottom  a  running  sand,  a  wooden  bottom  should  be  put  in  either 
as  a  platform  or  as  a  cradle.  Care  must  be  taken  to  have  gravel, 
sand,  or  "ashes  well  tamped  under  and  behind  such  wooden  sup- 
ports, and  the  wood  must  be  below  the  permanent  level  of  the 
ground  water. 

There  is  not  any  basis  for  computation  of  sizes  of  timbers  in 
the  design  of  such  a  timber  platform,  base,  or  cradle,  since  the 
supporting  power  of  the  natural  soil  is  quite  uncertain.  It  is 
necessary  to  provide  ample  stiffness,  and  it  is  better  to  err  by 
burying  too  much  timber  rather  than  not  enough.  For  an 
average  platform,  cross-timbers  in  a  trench  about  3  feet  wide 
should  be  about  4X4,  and  in  a  trench  8  or  10  feet  wide  they 
should  be  about  6X8. 

The  wooden  platform  used  under  30-inch  sewers  in  Manila 
consisted  of  cross-timbers  4X8  inches,  laid  across  the  bottom 
of  the  5-foot  trench,  and  the  floor  was  made  of  2-inch  plank, 
laid  longitudinally  on  these  stringers.  The  planking  running 
longitudinally  in  a  trench  should  be  spiked  to  the  cross-timbers, 
the  latter  spaced  about  5  feet  apart.  Great  care  should  be  taken 
to  pack  gravel  around  the  timbers  and  under  the  floor  plank,  in 
order  to  secure  good  bearing. 

Fig.  157  shows  a  wooden  cradle  suitable  for  the  outside  of 
either  brick  or  concrete  work.  Such  a  cradle  will  usually  be 
from  8  feet  to  10  feet  long,  depending  on  the  size  of  the  sewer, 
large  sizes  requiring  shorter  lengths  in  order  to  keep  the  weight 
of  the  cradle  within  reasonable  limits. 

The  frames  are  sawed  from  2  X  lo-inch  plank,  and  are  spaced 


FOUNDATIONS 


197 


about  4  feet  apart  if  2-inch  lagging  is  used,  and  about  18  inches 
apart  if  i-inch  lagging  is  used.  These  cradles,  in  continuous 
line,  are  carefully  set  to  grade,  the  space  between  their  outside 
and  the  trench  sides  is  thoroughly  filled  with  sand  or  gravel,  and 


Fig.  157 

often  the  top  of  the  frames  is  nailed  to  the  bracing  of  the  trench. 
They  are,  of  course,  left  in*  place  permanently,  and,  therefore, 
ought  to  be  used  only  under  the  level  of  ground  water. 

Instead  of  the  plank  in  the  bottom,  or  sometimes  on  the  plank, 
if  the  bottom  is  so  soft  that  concrete  thrown  directly  on  to  the 
mud  would  be  injured,  concrete  is  used  as  a  foundation.  This 


198  SEWER   CONSTRUCTION 

may  be  either  as  a  part  of  the  sewer  itself,  the  invert  being 
increased  in  thickness,  or  as  a  separate  construction.  The  use 
of  an  added  mass  of  concrete  for  a  foundation  course  is  generally 
not  to  be  advised,  since  the  weight  of  the  concrete  itself  adds  to 
the  insecurity  of  the  foundation.  The  lighter  weight  of  the 
timber  has  a  decided  advantage.  If  concrete  is  to  be  used,  as 
it  should  be  in  all  cases  above  ground-water  level,  the  thickness 
should  be  reduced  as  much  as  possible,  and  the  resistance  to 
flexure,  both  longitudinal  and  transverse,  obtained  by  metal 
reinforcement.  By  this  means  a  tough,  stiff,  and  permanent 
light  platform  may  be  placed,  which  does  not  need  to  be  below 
water  level,  and  the  cost  of  which  is  but  little,  if  any,  more  than 
a  timber  one.  The  thickness  need  not  be  more  than  6  inches, 
and  the  various  forms  of  wire  cloth  or  similar  metal  reinforcement 
are  suitable. 

A  last  resort,  when  the  earth  seems  to  have  little  or  no  sus- 
taining power,  or  is  so  variable  as  to  indicate  that  the  vertical 
alignment  of  the  sewer  would  be  quite  destroyed,  is  to  drive 
piles  and  thus  support  the  sewers.  Colonel  Waring  *  invented 
and  made  use  of  so-called  saddle  piles,  which  were  pieces 
of  2-inch  plank  10  to  12  inches  wide  sharpened  at  the  lower 
end  and  so  driven  in  the  bottom  of  the  trench  that  the  pipe 
would  rest  in  notches  cut  in  the  upper  end,  a  pile  coming  just 
behind  the  bell  of  each  pipe.  Mr.  Hastings,  at  Cambridge, 
has  driven  lo-inch  piles  4  feet  apart  in  the  bottom  of  the  trench, 
capping  them  with  a  4  X  1 2-inch  spruce  timber,  and  resting 
the  lo-inch  pipe  on  triangular  blocks  spiked  to  the  longitudinal 
timbers.  See  Fig.  158  for  drawings  showing  the  construction 
when  the  pipe  is  reinforced  with  a  brick  arch,  as  well  as  when  it 
is  not. 

Fig.  159  shows  a  more  elaborate  design  intended  for  an 
1 8-inch  pipe,  the  piles  being  double  in  the  bent,  and  the  bents 
spaced  5  feet  apart. 

Fig.  160  shows  the  design  by  the  same  engineer,  Mr.  Hastings,2 
for  an  egg-shaped  sewer  24  X  30  inches.     The  timbering  in  all 
1  Sewerage,  pp.  58  and  108.  '  Assn.  Eng.  Soc.,  Vol.  22,  p.  92. 


FOUNDATIONS 


199 


these  cases  is  about  the  same,  —  a  4-inch  floor,  8-inch  longitudinal 
timbers,  and  pile  bents  spaced  5  feet  apart. 

Fig.  I6I1  shows  the  construction  adopted  in  the  case  of  an  egg- 
shaped  26  X  39-inch  sewer  in  Lynn,  Mass.  A  single  row  of  piles 
were  driven  longitudinally,  6  feet  apart,  capped  with  6  X  6-inch 
timbers  as  shown,  braced  by  3  X  4-inch  diagonals.  The 


X  Drift-Bolt 
IIIJjLXx  6 'spruce 
g  4  x  8  Spruce 
N   4  x  10  Spruce 

Tree  Nail 
Piles  4 'apart 


Fig.  158 

stringers  are  4X6  inches  on  the  ends  and  6X6  inches  in  the 
middle,  covered  with  a  2-inch  spruce  floor.  The  concrete  foun- 
dation was  placed  on  this  floor,  confined  between  the  2-inch 
sheeting  shown.  The  piles  were  from  35  to  38  feet  long,  and 
in  spite  of  this  support,  filling  to  one  side  of  the  sewer  has 
crowded  the  sewer  sideways  about  4  feet  for  a  distance  of  125 
feet. 

Fig.  162  shows  the  design  adopted  in  Troy,  N.Y.,  some  years 
ago.2  The  egg-shaped  brick  sewer,  24  X  30  inches,  was  to  be 
carried  across  a  marsh;  and  a  timber  cradle,  supported  directly 
on  piles,  was  built.  The  frames  are  the  same  as  shown  in  Fig. 

1  Eng.  News,  Vol.  35,  p.  103.  2  Paving,  Vol.  8,  p.  314. 


2OO 


SEWER   CONSTRUCTION 


bO 

£ 


FOUNDATIONS 


201 


157;  but  instead  of  the  parts  being  fastened  together  into  one 
continuous  frame,  the  two  side  pieces  are  bolted   to   the  piles 


Fig.  1 60 

and  to  the  cross-timber,  and  then  the  lagging  is  nailed  on  as 
before.     This  is  all,  of  course,  below  ground-water  level. 

Fig.  163  shows  the  supports  for  a  sewer,  the  barrel  of  which 
is  wood  staves,  3X8  inches.  In  this  case  no  longitudinal 
stringers  are  necessary,  and  the  pile  bents  are  spaced  8  feet 


202 


SEWER  CONSTRUCTION 


apart  instead  of  5.     This  construction,  also  a  design  of  Mr. 
Hastings,  is  adapted  for  an  outfall  in  shallow  water,  where 


the  bolts  required  may  be  placed,  by  a  diver  if  necessary,  where 
the  wooden  barrel  is  under  water  continually,  and  where  the 
upper  cross-piece  keeps  the  sewer  from  being  floated  away. 


FOUNDATIONS 


203 


Fig.  164  shows  the  construction  used  to  support  an  8  X  8J-foot 
and  a  9  X  i3~foot  sewer  at  Boston.1  There  are  5  and  7  piles 
respectively  in  the  bents,  driven  closer  together  in  the  bent  under 
the  abutments.  Both  sections  are  admirable  examples  of  type 


Fig.  162 

forms  of  self-contained  sewers,  i.e.,  sewers  built  above  ground, 
or  in  such  soft  material  that  no  dependence  can  be  placed  on 
the  soil  for  backing  or  support. 

1  Eng.  News,  Vol.  27,  p.  512. 


204 


SEWER   CONSTRUCTION 


Fig.  165  shows  the  cross-section  of  a  sewer  at  the  foot  of 
Canal  Street,  New  York  City.1  It  is  7  feet  high  by  16  feet  wide, 
and  supported  on  pile  bents,  containing  8  piles,  the  bents  being 


Fig.  163 

3  feet  apart.  The  timbering  on  the  piles  was  12  X  12  caps, 
floored  over  with  4-inch  plank,  and  protected  with  a  flagstone 
cover  of  3-inch  bluestone.  The  side  walls  were  large  concrete 

1  Trans.  Am.  Soc.  C.  E.,  Vol.  31,  p.  569. 


FOUNDATIONS 


205 


Fig.  164 


206 


SEWER   CONSTRUCTION 


blocks  molded  in  forms  and  weighing  from  4  to  10  tons  each. 
The  roof  was  made  of  lo-inch  I  beams  spaced  3  feet  apart  with 
concrete  arches  between. 

Fig.  1 66  shows  a  similar  construction  at  St.  Paul,  Minn.,1 
the  sewer  being  16  feet  wide  by  12  feet  high.  Here  there  are 
9  piles  to  the  bent,  and  the  bents  are  6  feet  apart.  The  caps 
are  12X12  and  the  stringers  12  X  10  on  the  sides  and  10  X  10 
in  the  center.  The  side  walls  are  built  up  of  coursed  rubble,  and 

-T~  i    1    j    (    !' 


Fig.  165 

the  invert  of  the  sewer  is  formed  of  vitrified  paving  brick  set  in 
cement.  The  roof  is  formed  of  20-inch  I  beams,  spaced  5  feet 
apart  with  2 -ring  brick  arches  thrown  between.  These  latter 
have  a  radius  of  43  J  inches. 

In  all  these  designs  special  attention  should  be  paid  to  dis- 
tributing the  pressure  among  the  different  piles,  since  with  the 
sewer  flowing  only  part  full  the  pressure  under  the  abutments 
is  much  greater  than  at  the  center.  This  is  taken  care  of 
partly  by  the  spacing  of  the  piles  in  the  bent,  and  partly  by  the 
use  of  heavy  transverse  timbers.  It  is  easy  to  see  that  careless- 
1  Eng.  News,  Vol.  31,  p.  268. 


FOUNDATIONS 


207 


208 


SEWER   CONSTRUCTION 


ness  in  this  regard  might  result  in  a  longitudinal  break  at  the 
invert  and  at  the  crown. 

Sometimes  it  becomes  necessary  to  deliberately  allow  the  sewer 
to  settle,  making  due  provision  for  the  same,  as  was  done  in  Boston 
about  iSSo.1  The  outfall  sewer  from  Squantum  to  Moon  Island 
was  planned  to  be  built  in  an  embankment  20  feet  wide  on  top,  and 
about  30  feet  high  (see  Fig.  167),  the  embankment  being  formed 
by  newly  made  fill  on  the  mud  flats,  whose  elevation  was  about  that 
of  low  tide.  It  was  at  first  supposed  that  the  mud  was  underlaid 
by  gravel,  and  that  no  difficulty  would  be  encountered  in  making 


Position  1883, 


tion  1890 


130 
120 
110 
100 
90 
80 
70 


Fig.  167 

the  embankment  stable  from  the  first.  But  it  developed  that  the 
gravel  was  only  a  thin  stratum,  and  that  it  in  its  turn  was  under- 
laid by  mud.  A  temporary  box  sewer  was  built  on  piles  along- 
side, and  the  embankment  was  built  and  allowed  to  settle,  careful 
observations  being  made  as  to  the  rate  of  settlement.  For  this 
purpose  six  rods  were  placed  vertically  in  position  in  the  longi- 
tudinal axis  of  the  filling,  with  iron  plates  2  feet  square  at  their 
lower  ends,  which  were  set  at  the  top  of  the  embankment  as 
soon  as  it  was  brought  up  to  grade.  Additional  rods  were 
screwed  on  where  necessary,  and  levels  read  regularly  from 
above  on  each  of  the  six  rods.  For  nine  years  the  fill  was  allowed 
1  Assn.  Eng.  Soc.,  Vol.  11,  p.  355. 


FOUNDATIONS 


209 


to  settle,  and  Fig.  168  shows  the  settlement  from  1885  to  1890, 
the  total  settlement  in  the  four  years  prior  to  1885  being  as 
follows : 

Plate  at  Station  369  +    o 17  .09 


Plate  at  Station  374  .... 
Plate  at  Station  382  +  50..  .  . 
Plate  at  Station  389  +  22..  .  . 
Plate  at  Station  396+54..  .  . 
Plate  at  Station  401  +  79. ... 


3.89 

30-55 

1.26 

J-53 
i  .42 


1885 


0.1 


0.0 


0.3 


0.1 


0.5 


0.0 


o  Reliable  Observation 
•V  Unreliable  Observatioi 


Fig.  168 

The  diagram  shows  that  the  curves  are  all  gradually  approach- 
ing a  direction  parallel  to  the  axis  of  the  curves,  and  that  in  time 
the  settlement  would  cease.  In  this  case  the  construction  of  the 
masonry  sewer  was  begun  before  the  end  of  the  settlement, 
since  the  wooden  temporary  sewer  was  rotting  away,  and  the 
grade  of  the  sewer  was  raised  to  provide  for  an  estimated  future 
settlement. 

The  proper  design  of  a  foundation,  and  a  reasonable  adjustment 
of  the  character  of  the  foundation  to  the  necessities  of  the  particu- 
lar case  in  hand,  call  for  the  best  judgment  of  the  engineer,  and 
should  be  based  on  experience  and  observation.  Elaborate 


210  SEWER  CONSTRUCTION 

foundations  in  soils  which  may  not  require  them  may  indicate 
the  anxious  conservatism  of  the  constructing  engineer,  but  they 
are  extravagantly  expensive,  and  may  expose  the  ignorance  of 
the  engineer  quite  as  much  as  a  failure  of  a  sewer  due  to  insuffi- 
cient foundation.  A  municipality  before  entering  into  any 
extensive  foundation  work  for  sewer  construction  can  well  afford 
to  secure  advice  from  engineers  experienced  in  such  work,  rather 
than  follow  the  designs  of  a  local  engineer  whose  training  has  not 
given  him  the  special  knowledge  obtained  in  wider  practice. 


CHAPTER  XIV. 
OUTFALL  SEWERS. 

FREQUENTLY  the  term  "outfall  sewer"  is  applied  to  that  part  of 
the  sewer  system  between  the  point  of  discharge  and  the  last 
lateral,  or  between  the  point  of  discharge  and  a  pumping  station 
or  a  disposal  plant,  in  which  cases  no  special  construction  is 
required.  On  the  other  hand,  there  are  definite  and  peculiar 
forms  of  construction  used  in  the  building  of  the  discharge  end 
of  a  sewer  system. 

In  the  simplest  form  of  discharge  the  sewer  is  led  in  its  trench 
to  the  bank  of  the  stream  and  there  ended,  and  the  only  special 
construction  is  the  masonry  wall,  which  should  always  be  built 
around  the  end  of  the  pipe  to  protect  it  against  blows  from  above, 
and  from  erosion  of  the  water  from  beneath.  Fig.  169  shows  the 
design  of  Mr.  Hering  for  such  a  construction.1  Frequently  this 
form  of  construction  does  not  have  the  end  of  the  pipe  submerged, 
and,  the  pipe  being  high  out  of  water,  the  construction  of  the  wall 
is  a  simple  affair.  Proper  construction,  however,  demands  that 
the  outlet  be  submerged,  or,  if  the  sewer  is  a  combined  one,  that 
that  portion  which  carries  the  dry-weather  flow  be  submerged. 
This  may  conveniently  be  done  by  taking  out  a  smaller  pipe  from 
the  invert  of  the  large  sewer,  for  the  dry-weather  flow.  This 
small  pipe  can  be  carried  out  to  deep  water,  or  to  a  point  where  it. 
is  submerged  in  a  good  current,  far  more  easily  than  could  the 
larger  sewer.  In  Harrisburg,  Pa.,  for  example,  the  sewers  end 
at  the  foot  of  a  bank,  at  the  edge  of  the  Susquehanna  River.  In 
summer,  there  is  only  a  foot  or  so  of  water  flowing  over  the  rocky 
bed.  It  would  be  manifestly  impossible  to  carry  out  a  4-foot 
sewer  to  be  submerged  in  a  foot  of  water,  but  two  lengths  of 

1  Ithaca,  N.Y.,   1892. 


212 


SEWER   CONSTRUCTION 


lo-inch  pipe  carry  out  the  house  sewage,  and  the  large  sewer 
discharges  the  storm  water,  and  both  operate  without  producing 
any  nuisance. 

Fig.  170  shows  a  design  for  an  outfall  of  this  sort  in  Bingham- 
ton.  The  combined  sewer  is  4  feet  in  diameter,  and  the  outfall 
pipe  is  12  inches.  To  secure  a  freedom  from  flow  out  of  the 
big  sewer  except  in  time  of  storm,  a  concrete  dam  is  built  in  the 
big  sewer,  6  inches  high,  to  force  the  sewage  to  drop  through 


Fig.  169 

the  opening  into  the  smaller  pipe.  This  dam  is  not  usually 
necessary,  however,  unless  the  grade  is  very  high.  This  plan  is 
often  adopted  to  avoid  the  necessity  of  building  a  large  sewer  in 
a  deep  trench  or  down  a  steep  bank. 

Fig.  171  shows  a  conventional  design  recommended  by 
Moore,  and  Fig.  172  shows  the  actual  construction  of  the 
Niagara  Falls  outlet.  The  main  trunk  sewer  is  38  X  48-inch 
brick,  and  at  the  disposal  point  a  shaft  5X7  feet  is  sunk  below 
the  sewer  to  a  point  level  with  the  bottom  of  the  cliff,  exposed  in 
the  gorge  a  depth  of  about  50  feet.  A  sump  hole  allows  the 


OUTFALL   SEWERS 


213 


214 


SEWER  CONSTRUCTION 


falling  water  to  strike  without 
causing  damage.  From  the 
face  of  the  cliff  a  tunnel  is 
driven  5X6  feet  in  section 
to  the  bottom  of  the  shaft,  on 
a  10  per  cent  grade.  This 
tunnel  is  smoothed  up  on  the 
bottom  with  concrete  and 
brick  into  a  semicircular 
channel,  but  the  arch  is  left 
unlined.  The  mouth  of  the 
tunnel  is  protected  by  a  heavy 
masonry  arch  and  retaining 
wall.  Then  down  the  slope 
at  an  angle  from  the  horizon- 
tal of  38  degrees  is  laid  a 
3 -foot  circular  wood  pipe. 
This  pipe  is  anchored  at  the 
bottom  of  a  mass  of  70  cubic 
yards  of  stone  masonry 
thoroughly  tied  together  with 
iron  straps  and  collars.  A 
water  cushion  is  provided  at 
the  lower  end  of  the  pipe. 

Figs.  173*  and  174  show  a 
more  elaborate  construction  at 
the  mouth  of  the  Aramingo 
Canal  Sewer  in  Philadelphia, 
the  invert  at  the  outfall  being 
three  feet  below  low  water. 
Piles  were  driven  in  bents  in  a 
trench  from  which  the  soft 
mud  had  been  dredged  and 
which  was  then  refilled  with  gravel  and  cobbles.  On  top  of  the 
cobbles  was  a  cement  mattress  made  of  two  sheets  of  burlap  with 

1  Eng.  Rec.,  Vol.  44,  p.  614. 


OUTFALL  SEWERS 


Fig.  172 


173 


OUTFALL  SEWERS 

a  layer  of  cement  and  sand  between.  Then  on  this  mattress  con- 
crete blocks,  already  formed,  6  X  11X4  feet,  weighing  about 
1 6  tons  each,  were  set  by  a  derrick,  two  blocks  forming  the 
entire  bottom.  The  top  of  these  blocks  was  above  low  water, 
and  concrete  in  situ  was  used  for  the  side  walls.  At  the  extrem- 
ity an  end  wall  was  carried  to  the  bottom,  24  feet  below  low 
water.  For  this,  large  molded  concrete  blocks,  weighing  88 
tons,  were  used,  the  third  row  of  blocks  bringing  the  surface 
well  above  water. 

The  sewer  outlet  of  the  South  Metropolitan  District  of 
Boston l  is  an  example  of  a  submerged  outfall  of  unusually 
large  size.  (See  Fig.  175. )2  From  the  outlet  end  of  the  main 
sewer  on  Nut  Island,  five  6o-inch  cast-iron  pipes  extend  out  into 
the  tide  water  to  a  depth  of  about  38  feet  at  high  water.  These 
pipes  are  standard  1 2-inch  lengths  of  ball  and  socket  pipes, 
weighing  12,000  pounds  each,  and  extend  out  from  low- water 
line  about  one  mile.  The  pipes  were  jointed  in  48-foot  sections, 
and  floated  out  to  place  under  a  specially  designed  caisson. 
When  at  the  proper  point,  the  pipe  was  slowly  lowered  into  the 
trench  dredged  for  it.  The  joint  is  a  conical  lead  joint,  and 
the  pipes  were  aligned  and  drawn  together  by  divers  who  had 
powerful  ratchet  jacks  for  that  purpose.  To  aid  in  guiding 
the  pipe  into  place,  short  piles  were  driven  6  feet  apart  longitu- 
dinally, and  5  feet  apart  transversely.  The  outer  end  fits  into 
a  special  6o-inch  elbow  surrounded  by  a  rectangular  timber 
casing  resting  on  piles.  The  horizontal  flange  of  the  outlet  pipe 
is  capped  by  a  cut  granite  ring,  and  outside  of  this,  resting  on 
piles,  is  heavy  slab  paving. 

The  Broadway  outfall  sewer  of  New  York,  discharging  into 
the  Harlem  River  at  iQ2d  Street,3  is  a  twin  horseshoe-shaped 
sewer,  the  combined  capacity  of  which  is  equal  to  that  of  a 
1 6-foot  circular  sewer.  This  section  was  adopted  because  the 
sewer  grade  was  for  long  distances  above  the  level  of  the  ground, 
and  a  low,  flat  sewer  reduced  the  amount  of  filling  necessary. 

1  Eng.  Rec.,  Vol.  48,  p.  217.  2  Report  1899,  Plate  5. 

8  Eng.  Rec.,  Vol.  52,  p.  550. 


218 


SEWER  CONSTRUCTION 


OUTFALL  SEWERS 


219 


A  concrete  cradle  is  built  under  the  invert  with  two  layers 
of  brick  forming  the  invert.  At  the  extremity,  and  at  inter- 
mediate points,  piles  are  freely  used  to  support  the  weight  of  the 
masonry.  A  large  outlet  chamber  has  been  built  at  the  end,  so 
arranged  that  the  discharge  openings  are  submerged  i  foot  at 
low  tide  and  7  feet  at  high  tide.  The  chamber  (see  Fig.  176)  is 
trapezoidal  in  form,  57  feet  long  on  its  outer  side,  41  feet  long 


c 


Fig.  176 

on  its  inner  side  (the  width  of  each  sewer  is  15  feet),  and 
21.5  feet  wide.  The  height  is  22  feet,  the  heavy  concrete  roof 
being  carried  on  I  beams.  The  inverts  of  the  sewers  are  at 
mean  low  water,  but  in  the  chamber  a  flight  of  steps  brings  the 
sewage  down  and  out  through  openings  in  the  face.of  the  cham- 
ber which  are  entirely  submerged.  The  masonry  chamber  was 
built  in  a  timber  caisson,  floated  out  to  place,  and  sunk  on  to  the 


22O 


SEWER  CONSTRUCTION 


concrete  and  pile  foundation,  which  had  been  previously  placed 
directly  in  the  water. 

New  Rochelle,1  situated  on  an  arm  of  Long  Island  Sound,  has 
carried  its  outfall  sewer  across  Echo  Bay  and  through  tidal 
flats  whose  surface  is  only  a  few  feet  above  low  water.  The 
outlet,  a  30-inch  cast-iron  pipe  with  ordinary  lead  joints,  was 
laid  by  a  diver.  Four  lengths  of  pipe  were  placed  on  planks 
between  two  scows  and  the  three  joints  made  up.  A  chain  sling 
was  provided  for  each  pipe  so  that  by  attachment  to  overhead 
cross-timbering  the  pipes  were  lifted  off  the  plank  and  then 
lowered  into  the  trench.  The  joints  between  the  sections  were 
made,  by  the  diver,  with  jute  and  cold  lead. 

A  small  outlet  discharging  on  to  an  ocean  beach  was  installed 


Fig.  177 

at  Spring  Lake,  N.J.2  (See  Fig.  177.)  The  outlet  pipe  is  8-inch 
wrought  iron  with  screw  connections,  provided  with  flexible  joints 
at  intervals  of  40  and  80  feet.  It  is  650  feet  long  and  ends  in  20 
feet  of  water.  At  the  outer  end  is  a  heavy  cast-iron  anchor  plate, 
weighing  f  ton.  The  construction  is  simplicity  itself.  The  joints 
were  made  on  shore,  and  the  pipe  was  floated  out,  supported  on 
buoys,  and  sunk  by  cutting  loose  the  floats.  An  emergency  lo-inch 
wrought-iron  pipe  is  also  provided,  its  outer  end  fastened  to  a 
timber  pile  work  at  about  low  water  level.  Connection  with  the 
city  water  supply  is  provided,  so  that  if  necessary  a  strong  flush 
of  water  may  be  had  through  the  outlet. 

A  wooden  pipe  has  been  employed  where  the  outfall  is  to  be 
carried  out  into  deep  water,  as,  for  example,  at  New  London  in 

1  Eng.  Rec.,  Vol.  52,  p.  443.  a  Eng.  Rec.,  Vol.  42,  p.  617. 


OUTFALL   SEWERS 


221 


1892,  and  at  Ithaca  in  1894.  The  advantages  are  that  wood 
pipe  is,  or  has  been,  cheaper  than  cast  iron,  and  that  it  lends 
itself  to  launching  and  floating  into  place  more  readily.  Fig.  178 
shows  a  cross-section  of  the  New  London  pipe.  At  Ithaca, 
the  outfall  pipe  extended  6000  feet  into  Cayuga  Lake,  into  a 
depth  of  water  of  27  feet.  The  pipe  was  built  on  ways  at 


Fig.  178 


right  angles  to  the  shore  line  and  the  forward  end  carried  out 
into  the  lake  as  fast  as  the  pipe  was  built  in  the  rear.  The  pipe 
was  loaded  with  railroad  rails  for  sinking,  and  temporarily  held 
up  by  oil  barrels,  which  were  cast  off  when  it  had  reached  its 
place  and  was  ready  for  sinking.  It  was  shoved  forward  from 
behind  and  was  lined  up  with  temporary  piles.  A  detached 
section,  1500  feet  long,  was  readily  pulled  around  by  a  man  in  a 


222  SEWER   CONSTRUCTION 

row-boat.  At  New  London,  the  end  of  the  wood  pipe  ended  in  a 
heavy  anchor  plate,  and  an  elbow  with  a  conical  diverter.  In 
Ithaca  the  end  of  the  pipe  was  raised  on  a  box  of  stones,  just 
high  enough  to  give  a  clearance  of  three  feet  above  the  bottom. 

The  original  outfall  pipe  at  Old  Orchard  Beach,  Me.,  was  a 
six-inch  cast-iron  pipe,  joints  leaded  in  ordinary  fashion,  and  the 
line  of  pipe  $00  feet  in  length  held  together  by  a  chain  fastened 
to  each  pipe  and  running  from  end  to  end.  A  steamer  off  shore, 
by  means  of  a  long  hawser,  and  the  aid  of  small  toboggans  placed 
underneath  the  bells  to  make  the  sliding  easier,  pulled  the  pipe 
down  the  beach,  where  it  had  been  put  together,  until  the  outer 
end  was  in  about  8  feet  of  water  at  low  tide,  and  there  it  was  left. 

It  is  important  that  the  outer  end  of  the  pipe  be  so  arranged 
that  the  flow  of  sewage  does  not  cut  into  the  beach  and  undermine 
the  pipe. 

At  Burlington,  Iowa,  for  example,1  where  the  main  trunk  sewer 
discharges  into  the  Mississippi  River,  a  stone  spillway  was  entirely 
washed  away  in  1898.  The  sewer  in  two  parts,  one  10  feet 
and  one  12  feet  in  diameter,  ended  about  200  feet  back  from  the 
water's  edge,  and  about  20  feet  above  low-water  stage.  The 
sewage  was  supposed  to  flow  from  the  sewers  down  a  specially 
prepared  spillway  into  the  river.  A  number  of  piles  were  irregu- 
larly driven  into  the  slope,  and  stone  filling  placed  between.  The 
piles  were  capped  by  stringers,  and  a  wooden  floor  of  3  X  1 2-inch 
pine  planks  laid  on  top.  Then  paving  stones  on  edge  were  laid 
on  the  plank,  the  spillway  thus  formed  being  25  feet  wide  and 
about  ico  feet  long.  The  side  walls  were  4  feet  thick.  A 
summer  rainstorm  gorged  the  sewers,  and  tore  out  the  flume 
completely,  the  estimated  velocity  of  the  sewage  down  the  spillway 
being  20  feet  per  second.  The  repairs  were  most  thorough, 
and  the  construction  is  shown  in  Fig.  179;  438  piles  were  driven 
under  the  new  spillway,  with  an  average  length  of  137  feet.  Rip- 
rap was  then  placed  by  hand  between  the  piles,  and  the  voids  were 
filled  with  gravel.  Above  the  riprap  was  a  bed  of  concrete, 
3  feet  thick,  with  paving  blocks  for  the  wearing  surface.  Heavy 

1  Paving,  Vol.  19,  p.  267. 


OUTFALL  SEWERS  223 

side  walls  8  feet  thick  were  built  to  confine  the  flow,  and  a  seg- 
mental  arch  cover  turned  between,  the  whole  carried  down  to 
low  water.  The  flow  line  was  in  the  form  of  a  reversed  curve 
instead  of  an  inclined  line,  in  order  to  deliver  the  flow  horizon- 
tally, and  not  cut  into  the  bottom.  Such  a  structure  is  expensive, 
the  published  cost  of  this  being  $22,419. 

At  Los  Angeles,  the  outfall  was  a  line  of  24-inch  cast-iron 
flanged  pipe  extending  600  feet  into  the  ocean,  laid  on  the  slop- 
ing beach.  Rings  of  pure  rubber  f  inch  square  were  laid 
between  the  flanges  of  these  pipes.  The  pipe  was  put  together 
on  timber  stringers,  resting  on  rollers,  so  that  by  capstans  the 
whole  could  be  forced  out  into  the  water.  No  method  of  anchor- 
ing or  fastening  the  pipe  was  adopted,  although  it  was  exposed 
to  the  full  action  of  the  Pacific  Ocean.  The  outer  end  was  sub- 
merged in  about  20  feet  of  water.  This  pipe  was  put  in  place  in 
November,  1893,  but  within  two  years  the  strong  littoral  currents 
shifted  the  pipe  15  feet  out  of  alignment,  and  broke  it  at  a  point 
about  100  feet  from  shore.  The  sewage,  coming  through  the 
pipe  at  high  velocity,  due  to  the  8  per  cent  grade,  cut  out  a  large 
basin,  into  which  section  after  section  of  the  pipe  fell,  finally 
affecting  the  brick  sewer  on  land  and  the  very  bluff  itself,  which 
was  rapidly  undermined.  The  cutting  was  temporarily  stopped 
by  driving  sheet  piling  at  the  toe  of  the  bluff,  and  carrying  the 
sewage  out  through  a  wooden  trough  into  deep  water.  Within 
the  past  few  years  an  entirely  new  outlet  has  been  laid  in  connec- 
tion with  an  overhauling  of  the  long  outfall  from  the  city  to  the 
ocean. 

Fig.  1 80  shows  a  riveted  steel  pipe  4  feet  in  diameter,  built 
in  Toronto  in  1892,  to  carry  the  Parliament  Street  sewer  out 
into  the  deep  waters  of  Lake  Ontario.  The  entire  structure  is 
below  water  and  was  put  together  by  a  diver.  The  author 
has  seen  similar  construction  used  to  carry  sewers  into  Lake 
Michigan. 

As  the  summary  of  this  chapter  it  may  be  said  that  there  are 
a  number  of  ways  of  making  the  final  discharge  of  sewage  into 
the  body  of  water  which  is  to  receive  it. 


224 


SEWER  CONSTRUCTION 


OUTFALL   SEWERS 


225 


226  SEWER    CONSTRUCTION 

It  may  be  enough  to  let  the  sewer  project  through  a  small 
retaining  wall  on  the  bank  of  the  stream. 

It  may  be  necessary  to  enter  the  invert  of  the  main  sewer 
with  a  small  pipe  in  order  to  carry  the  dry-weather  flow  out 
under  water. 

It  may  be  necessary  to  carry  the  sewer  full  size  out  into  deep 
water,  supporting  the  sewer  on  piles  and  grillage,  or  laying  one 
or  more  large  submerged  pipes. 

Submerged  pipes  may  be  jointed  on  shore  and  pulled  out 
into  the  water  lengthwise,  or  they  may  be  put  together  from 
scows  and  sunk,  or  they  may  be  jointed  in  sections,  floated  out  to 
place  in  caissons,  sunk  and  jointed  by  divers. 

By  the  use  of  wooden  outfalls  for  small  sewers,  some  advan- 
tage is  gained  over  iron  pipe,  since  the  wood  pipe  can  be  floated 
in  great  lengths.  It  has  to  be  weighted,  however,  to  sink  it. 
The  author  remembers  one  large  box  sluice  built  a  half-mile 
long  to  carry  sewage  from  the  en4  of  the  pipe  sewer  to  the  dry- 
water  channel  across  a  mud  flat.  It  was  supposed  that  the 
box  was  properly  fastened  down,  but  a  high  tide  lifted  it  from 
its  fastenings  and  floated  it  out  to  sea. 

Finally,  the  sewer  may  end  at  the  bank,  and  a  pipe  or  a  paved 
incline  may  be  built,  but  care  must  be  taken  or  the  velocity  of 
the  flow  will  tear  out  the  structure.  There  is  also  danger  that 
in  shallow  water  the  flow  will  undermine  the  bank  and  so 
endanger  the  structure,  even  if  a  pipe  line  is  used  extending 
many  feet  out  from  the  water's  edge. 


CHAPTER  XV. 
HOUSE  CONNECTIONS. 

THE  purpose  of  a  sewer  system  is  the  removal  of  storm 
water  from  the  streets  and  the  removal  of  domestic  sewage  from 
the  houses.  For  the  former  purpose  catch-basins  in  the  streets 
as  already  described  afford  the  connection.  For  the  latter,  lines 
of  pipes  known  as  house  drains  must  be  built  from  the  street 
sewer  to  the  house  plumbing.  The  house  drains  are  usually 
of  sewer  pipe  and  connect  with  the  sewer  by  means  of  a  Y  or  a 
T  branch.  The  latter,  while  more  convenient  in  laying,  does 
not  permit  as  smooth  an  entrance  of  the  house  drainage  into  the 
sewer,  and  Y  branches  are  therefore  always  to  be  preferred. 
To  connect  properly  such  a  branch,  a  one-eighth-bend  must  be 
used,  and  the  house  drain  is  thereby  set  over  sideways  about 
fifteen  inches,  as  shown  in  Fig.  181,  due  allowance  for  which 
must  be  made  in  opening  the  house-drain  trench.  For  this 
reason  it  is  important  to  record  the  kind  of  branch  used, 
whether  Y  or  T,  for  the  benefit  of  drain  layers.  The  prelim- 
inary location  of  the  branches  is  largely  a  matter  of  estimate, 
but  before  the  contractor  orders  his  material  he  must  be  given 
the  exact  number.  The  general  rule  is  to  place  a  branch  for 
each  lot  on  each  side  of  the  street,  and  for  a  preliminary 
estimate  the  distance  apart  of  the  branches  on  each  side  of 
the  sewer  may  be  taken  as  the  average  width  of  the  city  lots. 
For  exact  determination  the  number  of  lots  must  be  counted  for 
each  line  of  sewers,  keeping  those  of  each  block  separate.  In 
undeveloped  areas  the  probable  future  width  of  the  lots  must 
be  assumed.  A  final  statement  can  then  be  prepared  giving 
the  number  of  branches  for  each  size  of  pipe. 

For  brick  sewers  the  house  connection  is  made  by  means  of 

227 


228 


SEWER   CONSTRUCTION 


"slants"  built  into  the  brickwork  at  the  proper  points.  These 
are  properly  located  above  the  horizontal  diameter  of  the 
sewer,  that  is,  in  the  arch,  and  should  slant  in  the  direction  of 
the  flow  of  the  sewer,  so  that  a  one-eighth-bend  is  also  needed 
here.  In  the  brick  sewers  as  well  as  in  pipe,  the  branch  should 
be  inclined  upward  slightly,  both  to  save  excavating  in  the  house- 
drain  trench  and  to  give  the  house  drainage  a  good  entering 
velocity.  In  both  cases  the  refilled  earth  must  be  well  tamped 
under  the  branch  to  prevent  its  breaking  off,  and  if  the  trench  is 


Fig.  181 


deep  or  the  ground  soft,  a  shovelful  of  concrete  should  be 
added  under  the  branch.  The  one-eighth-bend  is  not  laid  until 
the  house  connection  is  made,  since  it  extends  out  beyond  the 
sides  of  the  trench,  and  the  Y  branch  is  closed  with  a  tile  cap. 
These  caps  are  cemented  in,  either  by  means  of  a  narrow  fillet 
around  the  edge,  or  by  filling  in  over  the  entire  cap,  first  with  a 
thin  layer  of  clay,  and  then  with  cement  mortar.  Where  clay 
is  used  the  cap  is  easily  removed  when  necessary.  In  wet  ground 
the  cap  should  be  carefully  set  and  never  omitted,  since  a  large 
amount  of  ground  water  may  enter  the  sewer  through  Y's  unless 
they  are  made  water-tight.  Since,  presumably,  all  the  Y's  will 
be  dug  up  later,  their  location  must  be  exactly  recorded.  This 


HOUSE   CONNECTIONS 


229 


is  best  done  by  measurement  from  the  center  of  the  nearest 
manhole  up  stream.  It  is  of  great  service  further  to  stand  a 
piece  of  wood  edging,  or  a  piece  of  2  X  4  vertically  in  the 
trench  directly  in  front  of  the  Y,  the  top  4  or  5  inches  below 
the  surface.  In  this  way  the  Y  is  located  at  the  surface  and 
the  strip  of  wood  can  be  followed  down  to  the  Y.  A  piece  of 
wire  has  also  been  used  for  this  purpose.  On  a  curbed  street 
a  mark  cut  in  the  curb  opposite  the  Y  will  aid  in  the  recovery. 


Fig.  182 


The  record  is  sometimes  made  by  noting  the  distance  up  stream 
from  where  the  side  lines  of  a  house  or  where  a  fence  line  pro- 
duced cut  the  sewer  line.  (See  Fig.  182.)  The  objection  to 
this  method  is  that  in  the  record  the  houses  and  their  respective 
side  lines  are  apt  to  be  confused. 

The  size  of  the  house  drain  is  determined  by  experience  and 
not  by  computation.  Probably  a  2-inch  pipe  would  carry  off 
the  sewage  of  the  average  house  at  a  reasonable  rate,  but  it  has 
been  found  that  the  danger  of  obstruction  in  small  drains,  both 
from  grease  and  from  cloths,  brushes,  etc.,  is  very  great,  and  the 
minimum  size  may  therefore  be  taken  at  4  inches.  Five-inch 
drains  are  common,  that  size  being  a  compromise  between  a 
four-inch  and  a  six-inch  pipe  and  also  just  large  enough  to 


230  SEWER   CONSTRUCTION 

admit  the  4-inch  cast-iron  soil  pipe  and  give  a  good  joint.  Prob- 
ably 6-inch  pipe  is  most  used,  however,  since,  it  is  argued,  if  the 
pipe  is  to  be  large  enough  to  prevent  obstructions,  there  ought 
to  be  no  half-way  measure  about  it.  The  Y  branches  on  the 
sewer  line  must,  of  course,  correspond  to  the  size  of  house  drain 
adopted.  In  cities  where  plumbing  regulations  are  in  force,  the 
size  of  the  house  drain  is  a  matter  of  law,  and  is  determined  by 
the  board  making  those  regulations.  The  grade  of  the  house 
drain  should  be  at  least  2  per  cent,  or  J  inch,  to  one  foot,  although 
the  drain  will  work  (but  with  constant  danger  of  stoppage),  at 
half  that  grade.  The  drain  should  be  as  carefully  laid  as  for  a 
sewer,  true  to  line  and  grade.  In  England  running  traps  at  the 
houses  are  made  of  terra  cotta,  and  are  provided  with  a  clean- 
out  branch  located  in  a  manhole,  so  that  rods  can  be  run  down 
the  drain  —  an  admirable  construction,  especially  on  flat 
grades.  In  this  country  the  running  trap  is  made  of  iron,  and 
if  the  drain  gets  stopped  up,  the  trench  must  be  reopened,  the 
pipe  taken  up,  cleaned  out,  and  relaid.  In  passing,  it  may  be 
noted  that  there  is  little  or  no  danger  of  house  drainage  freezing 
and  if  the  house  fixtures  permit,  and  the  grade  of  the  drain 
makes  it  desirable,  the  pipe  may  with  safety  come  to  within  a  foot 
of  the  surface  of  the  ground. 

Where  the  street  sewer  is  deep,  i.e.,  10  feet  or  more  below  the 
surface,  it  is  customary  to  extend  the  Y  connections  by  means  of 
a  vertical  pipe  up  to  within  about  6  feet  of  the  surface  in  order  to 
make  the  matter  of  house  connections  more  economical.  This 
is  done  either  by  using  T's  on  the  main  pipe,  and  setting  one  or 
more  lengths  of  vertical  pipe  on  them  (Fig.  183),  or  by  using 
vertical  elbows  on  the  Y  branches  (Fig.  184),  which  are  then  set 
horizontally.  The  author  prefers  the  former  method,  although, 
theoretically  perhaps,  the  latter  commends  itself.  Where  the  Y 
and  elbow  are  used,  the  weight  of  the  vertical  pipe  is  eccentric  to 
the  main  sewer  and  tends  to  break  away,  thus  letting  ground  water 
readily  enter  the  sewer.  If  the  side  connection  is  used,  concrete 
should  be  well  tamped  in  under  each  Y  and  elbow,  so  that  they  are 
firmly  held  in  position  to  carry  away  the  vertical  load.  Then 


HOUSE   CONNECTIONS 


23l 


again,  the  side  connection  in  a  trench  which  is  sheeted  will  usually 
extend  out  into  the  sheeting,  requiring  a  wide  trench  at  the  start, 
or  else  much  cutting  and  waste  of  lumber  to  set  the  connection. 
With  T  branches  on  the  top,  on  the  other  hand,  no  such  difficulty 
occurs.  Again,  a  T  branch  on  top  can  be  used  for  a  connection 
from  either  side  of  the  street,  and  no  confusion  in  the  records  can 
be  made  by  substituting  a  Y  on  one  side  for  one  on  the  other.  A 


Fig.  183 


double  Y  may  be  used,  as  shown  in  Fig.   185,  from  plans  for 
Manila,  P.I. 

Since  Y  or  T  pipes  are  expensive,  since  the  number  of  house 
connections  that  will  be  used  is  uncertain,  and  since  the  vertical 
pipe  needed  with  a  deep  sewer  adds  to  the  cost,  it  is  possible  that 
the  construction  of  house  connections  at  the  time  the  main  sewer 
is  built  may  involve  a  large  and  perhaps  unnecessary  expense. 
The  author  has  occasionally  built  a  deep  outfall  sewer  without 
house  connections,  and  later,  when  the  growth  of  the  city  demanded 
it,  built  a  shallow  6-inch  line,  one  block  at  a  time,  emptying  into 
the  deep  sewer  at  the  manhole,  and  so  saved  money.  For  exam- 


232 


SEWER   CONSTRUCTION 


ELEVATION 


pie,  a  4-inch  branch  out  of  a  2-foot  length  of  24-inch  sewer  costs 
about  $5.00.  A  block  600  feet  long,  the  sewer  15  feet  deep, 
would  require 

24  branches  at  $5.00  each $120  .00 

24  elbows  at  50  cents  each 12  .00 

24  risers,  9  feet  long,  at  10  cents  per  foot 21  .60 

Concrete,  J  yard  each  at  $6.00  per  yard 48  .00 

Extra  excavation 50  .00     $251  .60 

Interest  for  10  years 125.80 

$377  .40 

Small  lines,  552  feet  of  6-inch  pipe  laid  at  30  cents $165  .60 

24  Y's  at  50  cents 12  .00 

24  elbows  at  50  cents 12  .00     $189  .60 


HOUSE   CONNECTIONS 


The  author  believes  that  in  many  cases 
economy  would  be  served  if  no  connec- 
tions were  provided  for  at  the  time  of 
construction,  but  that  a  two-story  line 
should  be  built,  the  construction  of 
the  upper  pipe  being  deferred  until  the 
development  of  the  territory  demanded 
it. 

Where  the  trench  is  in  rock  and  shal- 
low, so   that  Y  branches  are  to  be  built, 
it  is   well  to  put  a  charge  of  blasting 
powder  into  the  side  of  the  trench,  where 
the  house  connection  will  come.     Other- 
wise, when  the  blasting  for  the   house- 
connection  pipe  is  done,  the  main  sewer 
may   be    injured.      If, 
on  the  other  hand,  the 
rock  for  three  or  four 
feet    from    the    main 
sewer    is    all     broken, 
though    undisturbed 
otherwise,    this    loose 
rock  protects  the  main 
sewer  from  future  oper- 
ations. 

Where  the  street  in 
which  the  sewer  is 
ordered  is  to  be  paved 
in  the  near  future,  the 
house-connection  pipes 
should  be  laid  to  a 
point  just  within  the 
line  of  the  proposed 
curb.  This  causes 


Fig.  185 


some  loss,  since  not  all  of  the  connections  will  be  used,  but  the 
territory  will  be  well  built  up  if  paving  is  contemplated;  and  if 


234  SEWER  CONSTRUCTION 

the  wishes  of  the  property  owners  are  considered,  the  connec- 
tions will,  for  the  most  part,  be  adapted  to  immediate  use.  If 
these  cross-pipes  are  not  laid,  the  pavement  will  have  to  be  torn 
up  for  each  connection  made,  which  destroys  the  value  of  the 
pavement. 


CHAPTER   XVI. 
SURVEYING. 

THE  methods  of  surveying  outlined  in  this  chapter  are  those 
to  be  practiced  by  the  constructing  engineer.  The  chapter  will, 
therefore,  exclude  the  topographical  methods  required  to  prepare 
the  maps  from  which  the  design  is  made. 

The  first  task  of  the  engineer,  is  to  locate  the  sewer  line  on  the 
ground,  guided  by  the  paper  location  which  has  been  made  on 
a  scale  of  about  40  feet  to  an  inch,  such  a  map  showing,  as  far 
as  possible,  all  the  underground  structures.*  The  sewer  line  i*f 
located  with  due  reference  to  other  pipes,  in  some  streets  coining 
between  the  gas  and  water,  in  others  on  one  side,  avoiding  also  as 
far  as  may  be  the  storm  water  drains,  the  electrical  ducts,  and  any 
other  subsurface  pipes.  Under  ordinary  conditions,  for  an  inter- 
mediate trench,  there  ought  to  be  about  8  feet  between  pipes 
already  laid,  in  order  that  the  new  trench  may  not  cause  caving. 
If  the  old  trenches  were  each  3  feet  wide  there  would  be  5  feet  of 
undisturbed  earth  between  them,  and  a  3 -foot  intermediate  trench 
would  give  on  each  side  one  foot  only  of  stable  earth.  In  material 
like  sand,  which  needs  close  sheeting  under  all  conditions,  width 
enough  for  driving  the  sheeting  is  all  that  is  necessary.  In  a 
gravelly  loam  or  hard-pan,  the  undisturbed  solid  earth  will  probably 
stand  up  without  sheeting,  but  if  such  material  is  refilled  into  the 
side  trenches,  it  will  all  cave  into  the  intermediate  trench  unless  a 
wall  of  undisturbed  earth  intervenes. 

The  manhole  location  is  determined  by  the  position  of  the  pipe 
lines  of  the  side  streets.  For  convenience,  with  the  new  sewer 
located  on  the  map,  the  distances  to  the  curb  or  to  the  housefronts 
are  scaled  and  noted,  and  then,  by  making  these  measurements  on 
the  street,  stakes  may  be  set  on  line.  The  approximate  location 

*  See  Plate  II  of  Sewer  Design. 
235 


236  SEWER  CONSTRUCTION 

of  the  point  of  intersection  can  be  found  by  marking  the  lines  in  the 
cross  street  by  a  couple  of  stones  or  even  by  pieces  of  sod,  and  lining 
in  these  two  points  by  eye  as  the  engineer  stands  on  the  line  of  the 
main  sewer.  A  variation  of  a  foot  is  not  important,  and  the  proper 
location  of  the  manhole  with  reference  to  the  laterals  can  easily 
be  made  to  a  less  distance  than  this.  A  nail  is  driven  in  the  street 
to  mark  the  center  of  the  manhole  thus  determined,  and  the  sewer 
line  is  carefully  chained,  beginning  at  the  lower  end  of  the  sewer  and 
recording  the  location  of  the  manholes  as  +  stations.  After  the 
main  sewer  from  end  to  end  has  been  chained,  then  each  lateral  is 
chained,  starting  at  the  junction  manhole  on  the  main  sewer. 

The  nails  marking  the  manholes  should  be  carefully  referenced 
to  nearby  objects,  so  that  they  may  be  easily  recovered.  At  least 
three  ties  should  be  taken  with  the  distances  recorded  to  tenths  of 
a  foot.  The  points  of  reference  should  be  clearly  denned,  for 
example,  not  merely  a  telegraph  pole,  but  the  center  of  the  head 
of  a  nail  driven  well  into  the  side  of  the  pole. 

The  nails  at  the  manholes  will  be  dug  up  when  the  trenches  are 
opened,  and  it  is  a  waste  of  time  to  leave  permanent  marks  on  the 
sewer  line.  Some  engineers,  however,  line  in  this  chaining  with 
a  transit,  leaving  nails  driven  at  the  50  or  25-foot  points,  and  also 
drive  offset  spikes,  which  are  measured  over  from  these  center 
line  nails.  The  stationing  of  such  spikes  will  of  course  not  be 
accurate,  but  no  very  great  discrepancy  should  exist.  A  better 
method,  the  author  believes,  is  to  have  on  the  sewer  line  only  the 
nails  marking  the  manhole  centers,  and  have  the  intermediate 
points  marked  altogether  on  the  offset  line.  To  do  this,  a  point  is 
located  on  an  offset  equal  to  two  feet  more  than  the  half  width  of 
the  trench,  that  is,  for  a  6-foot  trench,  the  offset  would  be  5  feet, 
always  on  the  same  side,  going  up  grade.  The  transit  is  then  set 
up  over  the  offset  point  and  spikes  lined  in  at  25-foot  distances, 
to  a  point  measured  over  at  right  angles  as  near  as  can  be  estimated 
from  the  nail  at  the  next  manhole.  When  the  distance  to  that 
manhole  has  been  measured,  the  transit  must  be  set  over  the 
manhole  center  again,  the  new  offset  point  set,  the  transit  set  up 
over  the  point  and  the  next  block  lined  in.  If  there  were  no  angles 


SURVEYING 


237 


at  the  manholes,  the  chaining  and  stationing  would  not  have  to 
be  interrupted,  but  as  there  always  is  an  angle,  greater  or  smaller, 
the  offset  chaining  is  always  broken.  (See  Fig.  186.)  It  is  con- 
venient to  have  the  two  offset  spikes,  necessary  at  each  manhole, 
set  when  the  first  chaining  is  done, 
if  a  transit  is  used  then.  But  if  no 
transit  is  used,  it  must  be  done  when 
the  offset  lines  are  established.  It 
saves  a  large  amount  of  time  later, 
if  the  trenching  is  soon  to  follow,  to 
protect  the  offset  spikes  and  enable 
them  readily  to  be  found,  and  if 
sewer  pipe  has  been  brought  onto 
the  ground,  a  pipe  set  vertically 
around  and  over  each  nail  keeps  it 
from  being  covered  or  injured.  The 
contractor  may  be  confused  in 
opening  the  trench  by  working  from 
offset  spikes,  and  he  must  be  watched 
until  his  understanding  has  been 
made  perfect. 

To  mark  the  offset  point  the 
author  has  found  railroad  spikes 
the  most  convenient  for  macadam 
and  asphalt,  although  a  4openny 
wire  nail  will  answer.  In  brick 
and  stone  block  pavement,  a  small 
movement  of  the  point  in  distance 
may  be  allowed  to  bring  the  spike  into  a  crack,  although  the 
line  must  be  held,  since  this  line  is  used  to  give  the  sewer 
line.  In  dirt  streets  a  spike  may  not  be  stable  enough  and  pins 
a  foot  long — made  of  one-quarter  inch  iron  —  may  be  necessary. 
If  the  road  has  been  metalled  at  all,  the  4o-penny  nails  will  stay  in 
place  when  driven  well  into  the  metal. 

The  trench  is  opened  from  these  offset  spikes  and  the  contractor 
should  be  furnished  with  a  profile  to  good  scale  showing  the  depth, 


Fig.  1 86 


238  SEWER   CONSTRUCTION 

marked  in  figures,  to  which  the  trench  is  to  be  dug.  When  the  trench 
is  within  a  foot  or  so  of  bottom,  grade  boards  should  be  set,  but  it 
is  not  desirable  to  set  them  earlier,  since  they  are  in  the  way. 

In  a  narrow  and  stable  earth  trench  no  sheeting  may  be  required. 
In  that  case  the  grade  boards  are  independent  of  the  sheeting. 
There  are  a  number  of  methods  of  placing  these  boards.  The 
simplest  is  to  place  on  edge  across  the  trench  a  two-inch  plank 
long  enough  so  that  it  may  have  about  two  feet  on  the  solid  ground 
on  each  side.  These  ends  are  then  covered  with  dirt,  or  piled  up 
with  stone  to  hold  the  boards  firmly  in  place.  Sometimes,  in  order 
to  get  these  planks  and  the  grade  line  attached  to  them  up  out  of  the 
way  of  the  shovellers,  the  planks  are  set  up  on  top  of  pipes  which 
are  placed  vertically,  and  filled  with  dirt  in  which  are  set  2-inch 
by  4-inch  sticks  well  down  into  the  pipes.  The  planks  are  then 
rested  on  the  pipes  and  fastened  to  the  2  by  4-5.  Sometimes  a  frame 
is  made  as  shown  in  the  sketch,  Fig.  187.  The  base  of  the  frame 
gives  stability,  large  stones  are  superimposed,  if  necessary,  and 
the  plank  are  held  by  pins.  Sometimes,  instead  of  the  ends  of 
the  plank  being  held  by  earth  or  stones,  stakes  are  driven  into  the 
ground,  one  on  each  side  of  the  trench,  and  the  plank  fastened  by 
nails.  (See  Fig.  188.)  An  iron  rod  is  preferable,  since  a  stake 
may  disturb  the  ground  sufficiently  to  cav£  the  bank  of  the 
trench.  Usually  the  plank  is  allowed  to  rest  directly  on  the 
ground  and  to  take  its  slope.  But  when  stakes  are  driven  on 
each  side,  points  are  often  marked  on  these  stakes  at  the  same 
level,  a  definite  and  convenient  integral  number  of  feet  above  the 
sewer  invert.  The  plank  is  then  nailed  with  its  top  edge  on 
these  marks  and  therefore  having  its  entire  edge  uniformly  at 
the  level  desired.  With  square  iron  pins  a  clamp  screw  is 
used  to  fasten  the  plank  to  the  pins,  the  grade  having  been 
first  marked  on  both  pins.  The  plank  in  all  cases  should  be 
about  25  feet  apart,  although  this  may  be  increased  to  50  feet  on 
a  good  grade.  The  sag  of  even  a  light  line  in  50  feet  is  quite 
appreciable,  and  if  the  grade  is  low,  one-eighth  inch  in  50  fcc-t, 
the  effect  of  the  sag  on  the  grade  is  very  apparent.  If  offset 
spikes  have  been  driven  every  25  feet  and  grade  boards  are 


SURVEYING 


239 


placed  by  these  spikes,  the  line  is  easily  obtained  by  simply 
measuring  over  with  a  tape  from  the  spikes.  Otherwise,  a  tran- 
sit must  be  used  either  on  the  offset  line  to  cut  in  intermediate 


points  or  by  setting  up  ahead  to  line  in  points  directly  on  the  grade 
boards.  Where  the  planks  have  not  been  set  level,  a  vertical  board 
must  be  nailed  onto  the  plank,  one  edge  on  line.  This  is  readily 


240 


SEWER   CONSTRUCTION 


done  by  marking  the  line  on  the  top  edge,  offsetting  from  the  spike, 
and  swinging  a  vertical  strip  of  wood  around  this  point  until  by 
a  plumb  bob  it  is  vertical.  The  strip  is  then  nailed  fast  and  the 
level  used  to  mark  a  point  on  the  strip,  either  cutting  a  small  notch 
in  the  corner  of  the  strip  or  driving  a  small  finishing  nail  in  side- 
ways at  the  right  level.  If  the  plank  has  been  set  at  the  right  level 
the  vertical  strip  is  not  needed  and  the  small  nail  is  driven  vertically 
into  the  top  of  the  plank,  the  line  being  found  from  offset  measure- 
ments or  from  direct  transit  alignment.  The  grade  points  being 
thus  established,  a  line  is  stretched  from  nail  to  nail,  the  invert 
grade  being  a  certain  number  of  feet  directly  below. 


WASHINGTON    STREET, 
at  Center  of  Main  St.      Elevation,   16.470.  Grade  to  Center  St.  0.50. 


Sta. 

Surf 
Elev. 

B.  S. 

H.  I. 

F.  S. 

Sewer 
Elev. 

Depth 
Below 
Sur- 
face. 

Cut  on 
Grade 
Stake. 

H.  I. 

Rod 
Set- 
ting. 

B.  M. 

2O  04 

7   24 

28  18 

B.  S. 

o 

23    7 

4    5 

16  47 

7   2 

8 

6  17 

2   64 

20.94 

4-25 

2  ?    O 

4-1 

1  6  505 

7   7 

8 

27     II 

2    5I< 

4-  5o 

24    4 

16   72 

7   7 

8  &Q 

12    3.0 

+  <jc 

24    Q 

-7      •? 

16.845 

8    i 

o 

-jy 

1-39 

i  261? 

I4-O 

2^     2 

3.     O 

16  .07 

8.2 

9 

I    14 

+  25 

5 

26.1 

2  .1 

i7-°95 

9.0 

9  &  10 

{I    QIC 

M.  H.  +  3I 

26.  5 

I  .7 

17  .125 

0  -4 

IO 

B.  S. 

0.015 
4  .241? 

4-  so 

27    2 

I    O 

17    22 

IO    O 

IO  &  1  1 

4  16 

!4    15 

>   Ow 

27.21 

4  -AS 
3-15 

T  P 

27     21 

3    71 

3.0  02 

O  .07 

I  . 

21    .27 

4-  7C 

27    8 

31 

1  7    345 

IO    5 

1  1 

3O25 

>    /D 

28    4 

2    5 

1  7    47 

IO   O 

II    &  12 

!2    OO 

4-25 

2Q     I 

i  .8 

17  .505 

II  .5 

12    &  13 

>y 
I  .90 

(  I  .775 

4-  50 

?o  o 

o  o 

17    72 

12    3 

1  1 

*  Q-775 
o  65 

•  y 

4-7C 

2O    7 

I    2 

*/•/•' 

I  -    Sic 

110 

I  3 

o  525 

M   H  4-89 

2O    3. 

i  6 

17   015 

114 

o>5 
13    &  12 

!O   455 

l+O 

28  4 

2    5 

1  7  .07 

IO  .4 

12    &  II 

i-455 
11  40 

4-  25 

27    4 

7      C 

18  OQ5 

O    3 

II    &  IO 

•^ 

2  .40 
{2    275 

r  *$ 

3  275 

SURVEYING  241 

The  preceding  shows  a  page  of  the  author's  notebook  for  setting 
grades  on  Washington  Street.  At  station  o  +  50,  the  bottom  of 
the  rod,  for  an  8-foot  cut  has  reached  the  top  of  the  stake,  and  it 
is  necessary  to  decrease  the  rod  reading  and  increase  the  length 
of  grade  rod  each  by  a  foot.  The  cut  to  be  used  at  each  nail  or 
notch  ought  to  be  plainly  marked  on  the  stakes,  especially  where 
two  nails  for  two  cuts  are  driven  into  the  same  stake.  On  steep 
grades  it  is  more  rapid  to  use  a  transit,  setting  up  on  the  sewer 
line  ahead  of  the  work  on  solid  ground,  getting  the  elevation  of  the 
instrument  and  its  height  above  grade,  and  sighting  on  a  point 
down  grade  set  at  the  same  distance  above  grade.  Intermediate 
points  are  all  set  with  the  same  rod  reading,  which  is  the  distance 
above  grade  less  the  distance  desired  for  the  grade  line  to  be  above 
the  invert  grade. 

It  often  happens  that,  using  one  bench  mark  in  one  block  and 
another  in  the  next,  some  discrepancy  is  introduced  into  the  grade 
by  the  lack  of  agreement  between  bench  marks,  and  it  cannot 
be  too  thoroughly  urged  that  the  bench  marks  be  checked  and 
adjusted  before  any  construction  is  begun. 

Where  the  sewer  is  wide,  or  where  bracing  is  used  it  is  often 
more  convenient  to  nail  the  vertical  grade  boards  to  the  bracing 
instead  of  to  the  cross  planks  set  for  that  purpose.  Indeed  it  is 
usually  impossible  with  both  sides  of  the  trench  lined  with  sheeting 
to  find  any  place  to  put  the  cross  planks.  The  line  on  the  pieces 
of  bracing  is  found  just  as  before  described,  and  the  vertical  strips 
nailed  on,  and  the  grade  line  set  —  all  as  in  the  other  case.  The 
only  complication  comes  from  the  fact  that  the  distance  between 
grade  boards  is  irregular,  that  the  bracing  will  settle  as  the 
sheeting  is  driven,  and  so  the  grade  points  must  be  reset  after 
each  driving.  A  soft  bottom  or  caving  banks  will  also  carry 
these  grades  out  of  position,  and  in  quicksand  the  level  must 
be  in  constant  use  to  revise  the  grades  set  even  on  the  same 
day. 

The  preparation  of  estimates  is  the  remaining  work  to  be  con- 
sidered in  the  way  of  surveying.  Specifications  generally  read 
that  on  or  about  the  first  of  each  month  an  estimate  shall  be  made 


242  SEWER   CONSTRUCTION 

of  the  work  done  by  the  contractor  during  the  month  just  past. 
This  involves  the  measurement  of  the  number  of  feet  of  pipe  laid 
and  the  number  of  cubic  yards  of  excavation  made  both  of  earth 
and  rock,  with  the  number  of  manholes,  lampholes  and  other 
appurtenances.  The  method  of  computing  the  excavation  depends 
on  the  specifications,  but  the  most  reasonable  method  is  for  the 
specifications  to  prescribe  the  width  of  the  trench  that  will  be  paid 
for,  in  terms  of  the  diameter  of  the  pipe  and  of  the  depth  of  the 
pipe  invert.  There  should  be  room  on  the  outside  of  the  bell  for 
the  workman's  hands,  with  a  small  margin  for  alignment  of  the 
pipe,  a  width  of  12  inches  more  than  the  outside  diameter  of  the 
bells  being  a  reasonable  amount.  The  outside  diameter  of  the 
bell  for  a  12 -inch  pipe  is  17  inches,  so  that  the  trench  width  for  a 
i2-inch  pipe  should  be  29  inches,  the  width  to  be  used  in  estimating. 
A  6-inch  pipe  would  in  the  same  way  be  estimated  as  21 J  inches 
and  a  24-inch  pipe  as  43  inches.  These  are  minimum  widths  and 
would  probably  be  narrower  than  the  trench  would  actually  be 
dug.  This  would  be  particularly  applicable  if  sheeting  were  used, 
since  sheeting  as  ordinarily  driven  requires  for  one  row  6  inches 
additional  on  each  side.  Strictly,  then,  two  feet  should  be  added 
where  sheeting  is  to  be  used,  and  one  foot  where  the  trench  is  stable 
without  it.  The  specifications  might  therefore  well  differentiate 
except  for  the  opportunity  of  collusion  with  the  contractor,  who  by 
sticking  up  an  occasional  brace  in  the  trench  could  secure  a  measure- 
ment of  an  additional  foot,  the  engineer  being  willing.  It  would 
introduce,  without  collusion,  an  uncertainty,  the  contractor  being 
able  to  claim  the  additional  foot  whenever  he  decided  sheeting 
was  necessary  and  placed,  even  if  it  were  placed  only  for  the 
purpose  of  getting  the  extra  measurement.  It  is  better  then, 
in  ground  where  sheeting  will  probably  be  used,  to  make  the 
additional  width  two  feet,  but  where  the  ground  is  stable  to 
reduce  this  to  one  foot.  This  will  hold  to  depths  of  about 
10  feet.  Below  this  two  rows  of  sheeting  would  have  to  be  driven, 
so  that  the  upper  sheeting  would  require  another  foot  of  width, 
adding  three  feet  to  the  diameter  of  the  outside  of  the  bell.  It  is 
probably  fair  also,  since  the  cost  of  excavation  increases  with  the 


SURVEYING  243 

depth,  to  assume  this  width  to  continue  to  the  bottom  of  the 
second  row  of  sheeting,  even  though  the  actual  width  of  the 
trench  is  reduced.  In  rock,  where  no  sheeting  is  needed,  it  is 
simplest  and  at  the  same  time  is  perfectly  fair  to  assign  some 
width  for  all  sizes  of  pipe  up  to  12  inches,  the  width  varying 
with  the  depth  of  the  trench.  In  sedimentary  rock  this  can 
properly  be  made  3  feet  for  depths  up  to  8  or  10  feet.  For 
greater  depths,  that  is  8  to  16  feet,  4^  feet  and  over  16  feet  6 
feet  are  fair  widths  to  be  used  in  computation,  irrespective  of 
the  actual  width  of  excavation,  provided  the  specifications  have 
been  so  drawn.  For  sizes  12  to  24  inches,  ij  feet  should  be 
added  to  the  above.  With  the  widths  thus  fixed  by  the  speci- 
fications, the  computation  of  earth  work  consists  of  multiplying 
this  width  by  the  length  of  trench  excavated  and  by  the  depth. 
The  latter  is  usually  taken  from  the  profile. 

Records  of  Y  branches  is  another  important  part  of  the  sur- 
veying to  be  done  during  construction,  and  accuracy  here  is  most 
important.  There  are  two  methods  in  use.  One  is  to  measure 
carefully  from  the  nearest  manhole  up  grade,  afterwards  giving 
the  proper  station  number  to  the  Y  with  an  R  or  L  to  indicate 
which  way  it  looks.  The  objection  to  this  is  that  usually  the 
Y's  are  laid  before  the  manhole  is  built,  and  the  mason,  in  building 
up  the  manhole,  may  bring  the  center  of  the  cover,  presumably 
the  center  of  the  manhole,  a  foot  or  more  out.  Measurements, 
therefore,  taken  from  the  assumed  center  before  building,  and  the 
cover  center  after  building  will  not  agree,  and  will  make  Y's  hard 
to  find.  A  stake  may  be  driven  at  the  assumed  center  from  which 
measurements  are  made,  or  the  offset  spikes  may  be  used  to  locate 
the  Y's,  but  the  center  of  the  cover,  or  the  stake  driven,  must  have 
the  correct  station  number  determined  or  recorded  before  the 
stationing  of  the  Y's  is  made. 

Another  method  of  locating  the  Y's  is  by  reference  to  side 
lines  of  houses  which  are  built  near  the  Y.  The  record  book 
would  then  show  a  sketch  as  in  Fig.  182  and  to  recover  the  Y's 
the  side  line  of  the  house  shown  is  produced  by  eye  to  the  middle  of 
the  street  or  to  a  point  about  over  the  sewer  pipe,  and  then  the 


244  SEWER   CONSTRUCTION 

proper  distance  measured.  For  greater  certainty,  strips  of  wood 
such  as  edgings  from  a  saw  mill,  or  pieces  of  lath  or  pieces  of 
telegraph  wire,  are  often  left  vertically  in  the  trench  at  the  Y  so 
that  subsequent  excavation  may  first  find  the  upper  end  a  few 
inches  below  the  ground  surface  and  then  follow  down  to  the  Y 
with  perfect  certainty  of  finding  it. 


CHAPTER   XVII. 
TRENCHING. 

ORDINARILY  the  methods  used  in  laying  pipe  interest  the 
engineer  only  in  so  far  as  the  safety  of  the  pipe  line  and  the  water- 
tightness  of  the  joints  are  concerned.  Since,  however,  it  is  some- 
times required  that  the  engineer  act  as  contractor  and  immediately 
supervise  the  work,  some  reference  to  this  part  of  construction 
may  be  made. 

The  variations  in  methods  of  trenching  depend  on  the  charac- 
ter of  the  soil,  on  the  depth  of  the  trench,  and  on  the  amount  and 
depth  of  the  ground  water.  The  center  line  of  the  trench  being 
laid  out,  the  side  lines  are  marked  with  a  pick,  making  grooves 
in  the  surface,  and  the  laborers  are  strung  out  to  open  up.  The 
width  of  the  trench  is  determined  by  the  diameter  of  the  pipe,  and 
by  the  size  of  the  sheeting,  if  used.  The  full  outside  width  of  an 
8-inch  sewer  pipe  at  the  hubs  is  12  inches,  and  since  room  must 
be  left  outside  the  hubs  for  making  joints  and  for  correcting  the 
alignment  of  the  trench,  a  trench  two  feet  wide  is  the  least  width  to 
be  opened.  If  sheeting  has  to  be  used,  assuming  2-inch  sheeting 
with  4-inch  rangers,  another  foot  is  added,  making  a  3 -foot 
opening,  the  narrowest  where  sheeting  is  used. 

Some  contractors,  in  order  to  minimize  the  danger  of  banks 
caving,  open  the  trench  about  4  feet  wide  on  top,  narrowing  to 
1 8  inches  at  the  bottom  of  an  8-foot  trench,  thus  adding  about 
6  cubic  feet  of  excavation  per  linear  foot,  or  22  cubic  yards  per 
ico  foot  length,  an  additional  cost  of  about  $10.00.  The  sheeting 
for  100  feet  may  be  estimated  to  cost  about  $50.00,  so  that  the 
additional  excavation  is  apparently  justified,  if  the  sloping  banks 
allow  sheeting  to  be  discarded.  But  practically  any  trench  that 
will  stand  with  side  slopes  at  such  an  angle  will  stand  with  ver- 

245 


246  SEWER  CONSTRUCTION 

tical  sides  and  if  sheeting  is  needed  with  the  vertical  trench  it  will 
also  be  needed  with  the  sloping  sides.  It  is  better,  then,  to  have  the 
trench  sides  always  truly  vertical,  and  then,  if  bracing  becomes 
necessary,  it  can  be  put  in. 

In  rock  trenches,  the  width  depends  on  the  character  of  the 
rock,  on  the  depth  of  trench,  and  on  the  manner  of  excavation. 
If  the  rock  is  granite,  or  igneous  formation,  without  seams,  blast- 
ing will  remove  large  irregular  masses,  and  the  width  on  top  will 
be  nearly  equal  to  the  depth  of  the  trench.  In  sedimentary  rock, 
the  strata  may  be  kept  broken  off  so  that  the  width  is  but  little 
more  than  that  of  an  earth  trench.  In  deep  trenches,  however,  a 
batter  is  gradually  acquired,  a  trench  10  feet  deep  having  a  top 
width  of  about  4  feet.  If  blasting  is  freely  resorted  to,  with  deep 
holes  and  large  charges,  the  width  becomes  greater  than  with 
shallow  holes  and  small  charges,  though  it  is  possible  without  any 
blasting,  in  soft  sedimentary  rock,  to  carry  down  a  trench,  with 
picks,  bull  points,  wedges,  and  hammers,  and  have  a  trench  of  about 
the  same  width  from  top  to  bottom.  If  the  soil  is  dry  clay,  or 
dry  clay  loam,  a  trench  can  be  carried  down  without  any  sheet- 
ing, but  a  rain  storm  may  flood  the  trench,  soften  the  clay,  and 
cause  the  banks  to  fall  in.  A  dry  gravel,  or  sand  without  any  clay 
mixture,  will  need  tight  sheeting  to  hold  up  the  banks.  Wet  clay, 
or  sand,  will  also  need  tight  sheeting,  and  in  the  latter  cases  a  con- 
siderable pressure  is  exerted.  A  wet  trench  will  always  need  sheet- 
ing, which,  in  running  sand,  should  be  tongue-and-grooved,  or 
provided  with  splines. 

In  placing  the  sheeting,  the  trench  is  first  excavated  to  a  depth 
of  about  three  feet,  or  through  the  top  soil  and  into  the  water- 
bearing strata.  Then  the  two  rangers,  usually  16  feet  long,  their 
size  dependent  on  the  estimated  pressure,  and  varying  from  4  by 
4-inch  to  10  by  1 2-inch,  are  laid  along  the  trench,  one  on  each  side. 
Between  each  of  these  and  the  side  of  the  trench  are  placed  three 
pieces  of  sheeting  plank,  vertical,  one  at  each  end  and  one  in  the 
middle;  the  rangers  are  crowded  back  against  the  three  planks  and 
cross  struts,  or  braces,  wedged  in  tightly  and  driven  into  place. 
Then  the  trench  sides  are  lined  with  vertical  plank  driven  down 


TRENCHING  .  247 

behind  the  rangers.  When  these  are  all  in,  the  plank  standing  up 
out  of  the  trench  5  or  6  feet,  they  are  driven  down,  one  by  one,  as 
fast  as  the  trench  is  excavated,  special  care  being  taken  to  have  the 
sides  dug  vertical,  and  to  keep  the  bottom  ends  of  the  plank  back. 
When  the  trench  is  about  7  feet  deep,  another  set  of  rangers  or 
braces  is  put  in  to  hold  the  bottom  back,  and  the  plank  may  be 
driven  two  or  three  feet  below  these.  About  12  feet  is  the  maxi- 


Fig.  189 


mum  depth  for  a  trench  with  one  row  of  sheeting.  For  a  greater 
depth  an  inner  row  must  be  driven  with  the  first  ranger  of  the 
second  sheeting  holding  the  sheeting  back  against  the  bottom 
ranger  of  the  first  sheeting.  The  excavation  is  narrowed  up  in 
this  way  and  the  width  of  the  top  has  to  be  increased  on  this 
account.  Figure  189  shows  a  perspective  sketch  of  the  sheeting 
arranged  as  described.  For  ordinary  sewer  work  2-inch  sheeting 


248  SEWER  CONSTRUCTION 

is  generally  used,  and  for  the  braces  patented  screw  posts  are 
frequently  used.  Where  the  driving  is  heavy,  as  in  quicksand,  3 
or  4-inch  sheeting  is  often  necessary,  particularly  if  the  sheeting 
has  to  be  driven  ahead  of  the  excavation.  The  bottoms  of  the 
sheeting  plank  are  usually  sharpened  on  one  corner  and  along 
one  side,  so  that  the  driving  forces  them  sideways  against  the 
last  plank  driven,  and  back  against  the  bank.  An  iron  cap  is 
often  used  to  protect  the  ends  of  the  plank  from  brooming;  without 
the  caps,  a  wooden  maul  is  essential;  with  the  caps,  particularly 
when  a  hard  wood  block  forms  the  head,  an  iron  maul  may  be 
used,  or  the  plank  may  be  driven  with  a  small  pile  driver  rigged 
for  the  purpose. 

In  beginning  excavation,  it  is  often  possible  to  reduce  the  labor 
cost  of  the  top  three  feet,  where  the  width  permits,  by  using  horse 
scrapers,  ploughing  and  scraping,  instead  of  picking  and  shoveling. 
When  the  sheeting  and  bracing  is  in,  hand  work  is  necessary, 
although  machinery  may  be  used  for  conveying  the  dirt.  Machin- 
ery used  to  facilitate  sewer  excavation  is  usually  of  the  conveying 
rather  than  of  the  excavating  type,  although  rapid  advances  are 
being  made  in  the  effectiveness  of  the  latter.  The  former  machines 
are  employed  to  raise  loaded  buckets  from  the  bottom  of  a  trench, 
carry  them  the  necessary  distance  along  the  trench,  and  dump  the 
contents  wherever  backfilling  is  desired.  These  machines  are  of 
three  types  illustrated  by  the  Carson  Machine,  the  Lidgerwood 
Machine,  and  the  Moore  (or  Potter)  Machine.  The  Carson 
machine  (see  Figure  190)  *  consists  of  a  series  of  "A"  frames  which 
straddle  the  trench  and  are  connected  at  the  top  by  an  "I"  beam, 
which  serves  as  a  track  on  which  the  travellers  run.  A  hoisting 
engine  at  one  end  of  the  track,  with  a  return  pulley  at  the  other 
end,  supplies  power  by  which  the  buckets  attached  to  the  travellers 
can  not  only  be  moved  back  and  forth,  but  also  raised  and  lowered 
from  the  trench.  On  account  of  the  rental  and  maintenance 
charges  it  is  not  profitable  to  use  this  machine  until  the  trench  is 
over  8  feet  deep,  and  a  greater  saving  is  effected  the  deeper  the 
trench,  since  the  excavation  costs,  with  the  machine,  very  nearly  the 

1  From  Catalogue  of  Carson  Trench  Machine  Co. 


bh 


249 


250  SEWER  CONSTRUCTION 

same  amount  per  lineal  foot  of  trench  without  regard  to  depth. 
The  back-filling  is  done  without  additional  cost,  since  each  load  of 
the  machine,  instead  of  being  deposited  on  the  bank,  is  carried  to 
the  rear  and  dumped  back  into  the  trench.  The  cost  of  excava- 
ting and  refilling  by  these  machines  is,  in  deep  trenches,  much  less 
than  the  cost  by  hand  work.  The  Carson  catalogue  gives  the 
following  non-committal  statement: 

"  The  rate  per  cubic  yard  at  which  material  has  been  handled  by  our  machines  is 
a  matter  of  much  interest  to  contractors,  and  several  customers  have  told  us  that  they 
have  excavated  and  refilled  sand,  gravel,  and  clay  trenches  at  rates  varying  from 
fifteen  to  twenty-five  cents  per  cubic  yard.  These  figures,  however,  cannot  be  taken 
as  a  basis  for  general  estimates,  as  they  were  deduced  from  short  observations  only, 
and  do  not  include  the  cost  of  sheeting  and  bracing  the  trench,  pumpage,  loss  and 
wear  on  plant,  tools,  wastage  of  lumber,  or  miscellaneous  expenses,  all  of  which 
items  properly  come  under  the  head  of  excavation." 

"Again,  on  the  same  trench  there  is  often  considerable  difference  in  the  amount 
of  work  accomplished  from  day  to  day,  and  on  a  trench  in  one  locality,  where  the 
excavation  was  in  damp  sand,  we  have  seen  the  "Bolt  Machine  "  pushed  to  above 
its  rated  daily  capacity  (three  hundred  cubic  yards)  by  eight  shovellers,  yet  on  the 
same  trench  further  along,  where  clay  was  encountered,  it  took  sixteen  men,  or  four 
to  each  tub,  to  enable  the  machine  to  handle  one  hundred  and  fifty  cubic  yards  per 
day.  It  may  thus  be  seen  that  in  one  case  each  man  shovelled  nearly  four  yards  per 
hour,  while  in  the  other,  less  than  one  yard,  due  wholly  to  geological  variation." 

"  As  the  ability  of  those  using  the  machine  to  keep  it  in  running  order  is  another 
important  item,  it  can  easily  be  seen  that,  while  we  can  give  figures  as  to  the  cost 
per  cubic  yard  on  certain  jobs,  there  is  no  safe  general  average,  on  account  of 
variation  in  soil  and  circumstances." 

"We  have  had  several  contractors  tell  us  that  upon  the  same  trench  they  found 
that  with  our  machine  they  could  handle  excavation  at  about  one-third  of  the  rate 
per  yard  which  it  cost  them  in  their  experience  previous  to  using  machinery." 

The  Lidgerwood  Cableway  may  be  advantageously  used  where 
the  trench  is  too  wide  to  span  with  the  "A"  frames  of  the  Carson 
Machine,  or  where  for  any  reason  the  use  of  the  frames  is  not 
permissible.  Figure  igi1  shows  the  general  arrangement.  A 
frame  or  tower  at  the  rear  carries  a  loose  pulley  and  supports  the 
main  cable,  which  is  anchored  somewhere  in  the  rear  of  the  frame. 
The  head  end  has  its  tower  and  anchor  and  has  a  hoisting  engine 
which  moves  the  carriage  back  and  forth  with  the  tub.  The  usual 
span  is  from  225  to  300  feet,  so  that  the  apparatus  on  a  large  sewer 
does  not  have  to  be  moved  frequently.  It  is  not  difficult  to  move, 

1  From  Catalogue  of  Carson  Trench  Machine  Co. 


TRENCHING 

a  few  hours  sufficing  to  make  the 
necessary  change.  It  is  particularly 
useful  where  blasting  has  to  be 

done,  since  the  cable  is  not  likely?^ 

'  u 

to  be  damaged,  and  nothing  else  is  | 
in  danger.  Then,  too,  in  cities  it  is 
possible  to  cover  a  large  part  of  the 
sewer,  leaving  open  only  that  part 
where  excavation  is  being  carried 
on  and  that  part  where  dumping  is 
done.  It  does  not  place  any  load 
on  the  sides  of  the  trench,  either 
from  the  excavated  dirt,  or  from  the 
weight  of  the  apparatus.  There  is 
side  motion  enough  so  that  material 
can  be  placed  on  the  side  of  the 
trench,  or  material  can  be  picked  up 
from  the  side  and  placed  in  the 
bottom.  It  can  even  be  used  to 
draw  a  plough  or  scraper  and  exca- 
vate the  trench  without  picks  and 
shovel.  The  objection  to  its  use, 
aside  from  the  expense  of  installa- 
tion, is  that  it  can  handle  only  one 
thing  at  a  time,  and  that  it  is  pos- 
sible, without  good  superintendence, 
for  the  men  filling  a  bucket  at  one 
point  in  the  trench  to  do  a  good  deal 
of  waiting  for  their  bucket  to  be 
lifted.  The  machine  is  capableof  mak- 
ing 30  or  40  trips  per  hour,  but  without 
good  management  it  may  stand  idle 
half  the  time.  For  wide  trenches,  for 
rock  cuts,  and  for  excavation  in  quick- 
sand, the  cableway  has  manifest  ad- 
vantages over  the  Carson  Machine. 


252  SEWER  CONSTRUCTION 

The  Moore  Machine  and  the  Potter  Machine  are  similar  to  each 
other,  and  partake  of  both  of  the  characteristics  of  the  machines 
already  described,  that  is,  they  require  a  rail  laid  on  each  side  of 
the  trench  to  form  a  track  as  in  the  Carson  Machine,  and  the  opera- 
tion is  limited  to  one  action  at  a  time  as  in  the  Lidgerwood  Machine. 
Instead  of  providing  an  aerial  cableway  on  which  the  single  car 
can  move,  a  tower  car,  with  a  wheel  at  each  corner  post,  is  provided 
to  run  on  the  track  over  the  trench.  The  car  is  moved  back  and 
forth  by  an  endless  rope  attached  to  a  hoisting  engine  at  the  front 
end  supported  on  wheels,  and  to  a  dead  man  at  the  rear  end.  The 
Moore  Machine  has  a  carriage  about  8  feet  square  and  15  feet 
high,  which  carries  a  bucket  man,  who  directs  operations,  and  is  re- 
sponsible for  the  economical  use  of  the  time  of  the  machine.  The 
velocity  of  motion  attainable  is  high,  a  round  trip  of  the  carriage 
being  made  in  about  one  minute,  including  the  time  necessary  to 
raise  the  bucket  from  the  trench  and  to  dump  its  load.  The 
Potter  Machine  differs  from  the  Moore  in  that  the  track  on  which 
the  carriage  runs  is  elevated,  requiring  a  more  expensive  track  and 
a  less  extensive  carriage.  They  make  a  so-called  surface  track 
car,  which  then  in  principle  is  practically  the  Moore  Machine. 
In  a  lawsuit  between  the  two  companies,  tried  before  the  United 
States  Circuit  Court  of  Appeals,  March  5,  1901,  the  Potter  patents 
were  upheld,  so  that  no  danger  is  to  be  feared  in  using  their 
machines.  Figure  192  shows  a  photograph1  of  a  Moore  Machine 
track  in  use  at  Binghamton,  N.Y.  The  advantages  of  these 
machines  over  the  others  is  chiefly  in  the  greater  simplicity  of  the 
machinery,  most  marked  in  the  Moore  Machine.  The  hoist  is 
simple  and  the  engine  so  easily  handled  that  any  engineer  can 
operate  it.  These  machines  handle  only  one  bucket  or  two 
together,  but  they  are  more  easily  moved  ahead,  on  account  of  the 
lighter  engines  needed. 

The  matter  of  trenching  in  rock  introduces  uncertainty  on 
several  points.  The  cost,  the  time,  and  the  proper  method  of 
excavation  are  all,  in  the  minds  of  many  engineers,  indefinite  and 
uncertain.  The  kind  of  rock  determines  the  character  and  fre- 

1  Furnished  by  Thos.  F.  Moore,  President  Moore  Machine  Co. 


TRENCHING 


253 


254  SEWER  CONSTRUCTION 

quency  of  the  seams,  which  greatly  affect  the  ease  of  excavation. 
Limestones  and  shales  have  horizontal  strata,  usually  with  a  hard 
layer  overlying  a  softer  one.  The  vertical  joints  are  regular  and 
close  together,  so  that  it  is  possible  by  the  use  of  wedges,  bars,  and 
picks  to  excavate  in  sedimentary  rock  without  blasting.  Igneous 
rocks,  on  the  other  hand,  have  their  joints  so  far  apart  that  blasting 
is  necessary.  For  preparing  the  drill  holes  for  blasting  two  methods 
of  drilling  by  hand  are  available,  viz.,  by  a  churn  drill,  and  by  a 
hammer  drill. 

The  churn  drill  is  a  bar  of  iron  about  6  feet  long  with  steel  bits 
at  both  ends  and  weighted  with  a  ball  of  iron  in  the  middle.  It  is 
a  matter  of  some  skill  to  start  a  hole  with  a  churn  drill,  but  once 
started  the  drilling  proceeds  very  rapidly.  The  weight  of  the 
drill  furnishes  the  necessary  impact,  and  in  sizes  of  drill  rod  over 
three-quarters  of  an  inch  two  or  three  men  are  required  to  lift 
the  weight  of  the  rod. 

Trautwine  gives  the  following  table  for  the  rate  of  drilling  vertical 
holes  .3  feet  deep,  one  man  drilling  with  a  ij-inch  bit. 

Solid  quartz 4     feet  in  10  hours. 

Tough  horn  blend 6     feet  in  10  hours. 

Granite 7.5  feet  in  10  hours. 

Limestone 8.5  feet  in  10  hours. 

Sandstone 9.5  feet  in  10  hours. 

In  hammer  drilling,  one-hand  drilling  or  two-  or  three-hand 
drilling  may  be  employed  for  holes  up  to  3  feet  deep.     One  man» 
with  a  4§-pound  hammer  can  usually  drill  small  holes  more  cheaply 
than  when  one  man  holds  the  drill  and  one  or  two  men  are  striking. 
In  very  hard  rock,  however,  the  latter  may  become  cheaper. 

Gillette  says  that  with  one  man  holding  the  drill  and  two  men 
striking,  the  depth  of  hole  per  man  is  as  follows  for  a  6-foot  hole: 

( Granite 2$  feet  in  10  hours. 

Trap  (basalt) T,\  fi-t-t  in   10  hours. 

Limestone 5$  fei-t  in  10  hours. 

In  hard  porphyry,  the  same  author  gives  2  feet  to  3  feet  per  man 
per  day  in  holes  20  feet  deep  —  one  man  holding  and  two  striking; 


TRENCHING  255 

and  in  tough  sandstone,  one-hand  drilling  averaged  about  6  feet 
per  day  of  8  hours. 

The  spacing  and  depth  of  the  holes,  as  well  as  the  amount  of 
the  charge,  will  depend  on  the  methods  employed  and  on  the 
specifications  followed.  The  behavior  of  different  kinds  of  rocks 
is  most  confusing  to  the  foreman  who  meets  a  new  formation.  In 
soft  rock  and  in  sedimentary  rock  in  thin  layers,  properly  dis- 
tributed blast  holes  will  carry  down  a  trench  with  regular  and 
smooth  sides,  but  granite  and  igneous  rocks  are  broken  out  in 
irregular  and  uncertain  lines,  often  loosening  the  dirt  cover  for 
many  feet  on  each  side  of  the  trench,  if  not  actually  filling  the 
trench  with  such  dirt.  Most  specifications  require  excavation  in 
rock  to  be  carried  to  a  depth  six  inches  below  the  bottom  of  the 
pipe.  In  sedimentary  rock,  in  thin  layers,  or  when  a  thick  layer 
comes  just  above  the  excavation  bottom,  it  is  only  necessary  to 
drill  the  blast  holes  to  the  bottom  of  the  desired  trench.  But  in 
tough  granites  and  thick,  hard  limestones,  with  strata  disadvan- 
tageously  placed,  it  is  frequently  necessary  to  drill  a  foot  below 
the  trench  bottom  in  order  to  have  every  point  of  the  bottom  at 
least  6  inches  below  the  pipe.  The  usual  practice  of  placing  the 
holes  in  a  trench  is  to  space  them  about  three  feet  apart  longitu- 
dinally and  transversely  about  the  same  distance.  Thus,  in  a 
trench  3  feet  wide,  two  holes  are  drilled,  one  on  each  side  of  the 
trench.  In  a  trench  6  feet  to  8  feet  wide,  three  holes  would  be 
used,  one  on  each  side  and  one  in  the  middle.  In  a  trench 
14  feet  wide,  in  Newark,  N.  J.1,  five  holes  in  each  row  were  used, 
the  distance  apart,  longitudinally,  of  the  rows  being  4  feet.  In  soft 
limestone  the  author  has  for  trenches  for  6-inch  pipe  not  over 
8  feet  deep,  particularly  when  only  the  bottom  of  the  trench  was 
in  rock,  put  down  a  single  row  of  holes  in  the  middle  of  the  trench, 
but  a  large  amount  of  picking  and  hammering  is  always  necessary 
to  finish  up  the  work. 

As  to  the  depth  of  the  hole,  the  necessity  of  avoiding  accidents, 
excessive  noise,  and  rattling  in  nearby  houses,  limits  the  amount 
of  the  charge.  Usually  the  depth  of  the  holes  is  made  the  same 

1  Gillette. 


256 


SEWER  CONSTRUCTION 


as  the  distance  between  the  holes,  although  in  tough  rock  the  depth 
can  with  advantage  be  made  greater  than  that  distance.  The 
deeper  the  holes,  the  cheaper  the  work,  since  frequent  changing  of 
drilling  machines  means  loss  of  time.  Gillette  gives  the  follow- 
ing (theoretical)  table  to  show  the  effect  of  spacing  of  holes  upon 
the  cost  of  excavation,  tabulating  the  number  of  feet  of  hole 
drilled  per  cubic  yard  excavated: 


Distance  Apart  of  Holes. 

i 

2 

3 

4 

5 

6 

8 

10 

Cubic  yards  per  foot 
of  hole  

.04 

.iq 

.?? 

.CQ 

.03 

I    33 

2    37 

3    7O 

Foot  of  hole  per  cubic 
yard 

27 

6  8 

30 

I    7 

I    08 

7C 

42 

27 

Since  drilling  costs  from  10  cents  to  50  cents  per  lineal  foot,  an 
unwise  or  unforeseen  combination  of  high  cost  drilling  with  shallow 
holes  near  together,  may  very  easily  add  from  $1.00  to  $3.00  to  the 
cost  of  a  cubic  yard  of  rock  excavation.  In  loose  seamy  shale, 
shallow  holes  near  together  are  necessary  to  retain  the  force  of  the 
explosion. 

The  kind  of  explosive  which  may  be  used  varies  from  the  slow 
low-power  black  powder  to  the  rapid  high-power  nitroglycerine, 
the  many  forms  of  dynamite  and  high  grade  powder  in  use  being 
combinations  of  nitroglycerine  and  some  absorbent.  The  slow 
explosives  are  used  to  quarry  dimension  stone,  to  break  out  large 
blocks,  and  to  lift  clay,  hardpan,  or  shale.  The  rapid  explo- 
sives, on  the  other  hand,  are  used  in  tough  rock,  particularly  in 
rock  which  is  afterwards  to  be  shoveled,  and  therefore  needs  to  be 
broken  into  small  pieces.  Rapid  explosives  are  also  used  where 
the  rock  is  seamy,  or  cracked,  when  the  slow-forming  gases  might 
escape  without  shattering  the  rock.  The  most  efficient  blasting 
is  that  in  which  both  the  depth  and  spacing  of  the  holes  and  the 
grade  of  the  explosive  are  properly  adjusted  to  the  work  in  hand. 
Further  details  of  the  methods  of  placing  and  firing  the  blast  will 
be  found  in  the  standard  books  on  tunnelling  and  on  rock 
excavation. 


CHAPTER    XVIII. 
ESTIMATES  AND   COSTS. 

THE  matter  of  making  up  a  preliminary  estimate  of  the  cost  of 
sewer  construction  is  usually  most  unsatisfactory  for  the  engineer 
himself,  for  the  city  officials,  and  for  the  contractors  who  may  bid 
on  the  work.  Unless  the  engineer  has  had  large  experience  in  this 
line  of  work  and  in  the  particular  locality  where  the  sewer  system 
is  to  be  built,  the  estimates  may  vary  largely  from  the  actual  cost 
and  from  the  bids,  and  if  the  cost  must  come  within  an  appro- 
priation, an  estimate  which  is  too  small  is  certain  to  lead  to  future 
difficulties.  The  variation  in  the  estimate  as  a  whole  is  caused  by 
the  uncertainty  of  the  estimates  of  the  items  of  the  work.  Without 
a  series  of  borings  or  test  pits  the  character  of  the  soil  and  the 
cost  of  its  excavation  is  mere  guesswork.  For  example,  if 
rock  is  found  near  the  bottom  of  the  trench,  it  will  increase 
the  cost  of  the  trench  perhaps  50  cents  per  lineal  foot.  The 
engineer's  estimate  may  overlook  the  rock  and  count  the 
trench  at  perhaps  35  cents  per  running  foot,  whereas  with 
the  rock  he  would  estimate  the  cost  of  excavation  at  80  cents 
per  lineal  foot.  Similarly,  the  cost  of  sheeting  an  ordinary  trench 
with  single  sheeting  may  be  15  cents  per  running  foot,  and  while 
the  contractor  may  figure  on  sheeting,  the  engineer  may  omit  that 
cost.  Again  the  amount  of  ground  water  to  be  encountered  and 
the  consequent  cost  of  pumping  is  most  uncertain.  The  contractor 
may  figure  that  he  will  need  a  steam  pump  running  day  and  night 
at  a  daily  cost  (including  rent  of  boiler  and  pump,)  of  $18.00  per 
day,  or  an  additional  cost  for  pumping  of  10  cents  per  lineal  foot 
of  sewer.  The  estimated  cost  of  excavation  per  lineal  foot  for  a 
small  lateral  sewer,  then,  may  run  from  about  30  cents  in  good 
ground  to  $1.25  in  bad  ground,  the  difference  being  all  due  to  a 
different  opinion  as  to  the  amount  of  rock,  amount  of  sheeting,  and 
amount  of  pumping. 

257 


SEWER  CONSTRUCTION 

The  cost  of  excavation  of  earth  in  a  trench  is  somewhat  greater 
than  in  a  large  open  cut.  The  loosening  must  all  be  done  by  pick, 
and  some  extra  time  is  taken  in  trimming  and  preserving  the  line 
and  sides  of  the  trench. 

According  to  Gillette's  figures  revised  to  a  scale  of  wages  of  $1.50 
for  8  hours,  the  cost  of  loosening  earth  with  a  pick  ranges  from 
1 1  cents  per  cubic  yard  for  very  easy  earth  to  15  cents  per  cubic 
yard  for  very  stiff  clay  or  cemented  gravel,  and  for  average  earth 
the  cost  of  picking  may  be  taken  at  5  cents  per  cubic  yard.  He 
gives  the  cost  of  shoveling  dirt  which  has  been  loosened  at  13  cents 
per  cubic  yard. 

The  cost  of  picking  and  shoveling,  per  cubic  yard,  then,  from  a 
trench  will  be  as  follows,  the  cost  of  shoveling  increasing  also 
with  the  kind  of  soil: 


Picking. 

Shoveling. 

Total. 

Easy  earth,  sand,  and  loam                 .        

I  £  CtS. 

I3Cts 

i4Acts. 

Average  earth  

<T        " 

I<   " 

20      " 

Tough  clay  

10       « 

7  " 

27      " 

Hardpan  

30     " 

23  " 

53    " 

These  figures  are  confirmed  by  data  from  different  cities  and  are 
generally  applicable.  The  figures  do  not,  however,  include  any 
sheeting,  bracing,  pumping,  foreman,  contractor's  profit,  or  office 
expenses,  and  are  for  trenches  6  feet  deep  or  less. 

The  cost  of  back-filling  is  usually,  in  estimates  and  bids,  included 
in  the  cost  of  excavation,  and  should  therefore  be  added  to  the 
figures  given.  The  cheapest  method  of  returning  the  dirt  to  a 
trench  is  to  scrape  it  back,  the  horses  staying  on  the  side  of  the 
trench  opposite  the  bank,  the  scraper  having  a  rope  attached. 
In  good  soil,  this  may  cost  as  little  as  ij  cents  per  cubic  yard  if  no 
ramming  is  required.  The  cheapest  hand-filling  will  cost  without 
ramming  about  13  cents,  or  the  bare  cost  of  shoveling.  A  table 
from  the  Technic,1  1896,  gives  the  cost  of  back-filling  clay,  not 
including  ramming  as  21  cents,  27  cents,  28  cents,  and  34  cents,  this 

1  University  of  Illinois. 


ESTIMATES  AND  COSTS  259 

work  apparently  being  very  inefficient.  However,  if  clay  is  dug 
wet  and  piled,  and  allowed  to  dry,  it  becomes  so  hard  that  it  has  to 
be  picked  or  ploughed  before  it  can  be  shoveled,  which  may 
account  for  these  high  prices.  The  author,  refilling  trenches  in 
the  fall,  has  found  that  a  heavy  frost  adds  decidedly  to  the  cost  of 
refilling,  in  that  the  frozen  crust  has  to  be  picked  loose. 

If  the  trench  has  to  be  consolidated  by  ramming  or  puddling, 
something  more  has  to  be  added  to  the  cost.  A  common  specifi- 
cation is  that  there  shall  be  one  rammer  to  each  shoveler  employed 
in  back-filling,  in  which  case  the  cost  would  be  increased  by 
at  least  13  cents  per  cubic  yard.  In  city  streets,  where  the  con- 
solidation is  thorough  and  complete,  and  where  the  material  is 
clay  rammed  in  four  inch  layers,  the  cost  may  be  from  two  to 
four  times  this  amount,  in  fact  there  is  no  limit  to  the  amount  of 
ramming  that  may  be  put  into  a  clay  back-fill.  The  following 
summary  may  be  given : 

Excavation $o.  14^  to  $0.53 

Refilling ; ' oi£  to  .30 

Ramming,  if  done .13  to  .60 

Total $0.29  to  $1.43 

In  gravel  or  sand,  trenches  may  be  well  consolidated  by  refilling 
into  water.  A  firehose  may  be  allowed  to  run  as  the  refilling  is  in 
progress,  or  the  trench  may  be  half  filled  before  the  water  is  turned 
on.  Or,  again,  the  empty  trench  may  be  half  filled  with  water 
before  the  refilling  is  begun.  It  has  been  stated  by  an  experi- 
enced engineer  that  workmen  will  work  noticeably  faster  in  the 
latter  case  on  account  of  the  gratification  at  hearing  the  splash 
of  the  dirt. 

In  Vols.  27  and  28  of  the  periodical,  "  Engineering- Contracting/' 
some  complete  analyses  of  the  costs  of  trenching  and  back-filling 
were  given  for  Centerville  and  for  Atlantic,  both  in  the  state  of 
Iowa.  The  figures  were  compiled  by  Mr.  M.  A.  Hall,  engineer  in 
charge,  and  are  discussed  at  length  in  No.  20  of  Vol.  27,  and  in 
Nos.  8,  12,  16,  and  24  of  Vol.  28.  For  complete  understanding  of 
the  conditions  the  reader  is  referred  to  the  periodical,  and  the 
following  summary  is  given  chiefly  to  show  how  great  a  variation 


260  SEWER  CONSTRUCTION 

exists  in  the  cost  of  trenching  and  back-filling,  even  where  the 
conditions  are  apparently  approximately  uniform. 

At  Atlantic  *  on  eighteen  different  parts  of  the  work,  the  cost  of 
trenching  per  cubic  yard  varied  from  $0.131  for  a  lo-inch  pipe  in 
a  6.6-foot  trench  to  $0.347  for  a  15-inch  pipe  in  a  i2.6-foot  trench. 
The  back-filling  was  done  chiefly  by  scrapers,  and  cost  from 
$0.017  for  a  lo-inch  pipe  in  a  p.i-foot  trench  to  $0.066  for  an 
8-inch  pipe  in  a  9.6-foot  trench.  The  labor  of  pipe-laying  cost 
from  $0.013  for  a  lo-inch  pipe  to  $0.085  f°r  a  1 5-inch  pipe. 

At  Centerville 2  on  thirty-six  different  parts  of  the  work,  the  cost 
of  trenching  per  cubic  yard  varied  from  $0.239  f°r  an  8-inch  pipe 
in  a  6.6-foot  trench  to  $0.864  f°r  a  1 2-inch  pipe  in  a  12. 2-foot 
trench.  The  former  was  in  yellow  sand  clay,  easily  spaded,  and 
the  latter  in  dry,  hard  clay.  The  back-filling  cost  from  $0.041  for 
an  8-inch  pipe  in  an  8.7  foot  trench  to  $0.212  for  a  lo-inch  pipe  in 
an  8.8-foot  trench.  The  labor  of  pipe-laying  cost  from  $0.017  for 
an  8-inch  pipe  to  $0.099  for  a  1 2-inch  pipe  in  a  13 -foot  trench. 

On  thirty-nine  other  parts  of  the  work  at  Centerville 3  the  cost 
of  trenching  per  cubic  yard  varied  from  $0.173  f°r  a  1 5-inch 
pipe  in  a  5.6-foot  trench  to  $1.04  for  a  1 2-inch  pipe  in  a  9.9-foot 
trench.  The  former  was  in  black  loam  and  the  latter  was  through 
boulders  in  a  wet  ditch.  The  back-filling  cost  from  $0.033  f°r 
a  i5-inch  pipe  in  a  7.3-foot  trench  to  $0.244  f°r  an  8-inch  pipe 
in  a  10. 5-foot  trench,  this  latter  being  done  in  wet  weather.  The 
labor  of  pipe-laying  cost  from  $0.036  for  a  15-inch  pipe  to  $0.172 
for  a  lo-inch  pipe  in  a  1 2-foot  trench. 

On  fifty-three  other  parts  of  the  work 4  the  cost  of  trenching 
per  cubic  yard  varied  from  $0.141  for  a  i5~inch  pipe  in  a  7. 7-foot 
trench  to  $0.639  for  an  8-inch  pipe  in  a  9.i-foot  trench.  The 
former  was  in  good  easy  digging  and  the  latter  was  in  wet 
ground  with  some  quicksand.  The  back-filling  cost  from  $0.026 
for  a  i2-inch  pipe  in  an  8.2-foot  trench  to  $0.187  for  an  8-inch 
pipe  in  a  lo-foot  trench,  the  latter  being  due  to  wet  weather. 

1  Engineering-Contracting,  Vol.  27,  page  218. 

3  Engineering-Contracting,  Vol.  28,  page  114. 
8  Loc.  cit.  page  170. 

4  Loc.  cit.  page  223. 


ESTIMATES  AND   COSTS  261 

The  labor  cost  of  pipe-laying  varied  from  $0.035  for  a  lo-inch  pipe 
to  $0.124  f°r  an  8-inch  pipe  in  an  1 1.6-foot  trench  in  hard  clay. 

The  material  in  nearly  all  the  above  cases  was  clay,  very 
hard  when  dry,  and  very  slippery  when  wet.  The  laborers  worked 
10  hours  per  day  and  labor  is  computed  at  the  rate  of  20  cents  per 
hour. 

The  excavation  for  the  sewer  work  at  South  Bend  referred  to  on 
page  85,  was  done  largely  with  a  Potter  Trench  Machine.  With 
wages  at  18.5  cents  per  hour  for  laborers,  and  30  cents  per  hour 
for  the  engineer  on  the  machine,  the  cost  of  excavation  per  cubic 
yard  was  given  as  follows:1 

Pipe  for  sub-drain $0.047 

Labor  laying  this  pipe 0.050 

Pumping  water 0.065 

Excavation  and  back-filling 0.400 

Sheeting  and  shoring 0-150 

Tools  and  general  expenses 0.035 

$0.747 

This  does  not  include  the  rent  of  the  machine  nor  apparently  the 
cost  of  coal,  which  items  would  add  nearly  50  per  cent  to  the  cost 
given. 

This  same  kind  of  machine  was  used  for  the  deep  trenching  on 
Lawrence  Avenue,  Chicago,  where  a  sewer  was  built  in  1907. 2 
Here  laborers  were  paid  at  the  rate  of  34  cents  per  hour  and  the 
engineer  on  the  machine  75  cents  per  hour.  One-half  ton  of  coal 
was  consumed  each  day  by  the  machine  and  the  rent  of  the  machine 
was  given  as  $4.80  per  day.  The  total  daily  expense  was  as 
follows. 

One  engineer $  6.00 

One  fireman 2.50 

One  carriage-man 2.50 

One  carriage-man 3.25 

20  bottom  men 55-°° 

One  dump-man 2.75 

Foreman 3.50 

Coal  and  rent 7.30 

$8^80 

1  Engineering-Contracting,  Vol.  29,  page  70. 

2  Engineering-Contracting,  Vol.  28,  page  212. 


262  SEWER  CONSTRUCTION 

On  the  basis  that  175  cubic  yards  of  material  were  excavated 
each  day,  the  cost  would  be  about  47  cents  per  cubic  yard,  with  no 
allowance  for  sheeting. 

For  excavating  a  trench  for  a  water  pipe  for  the  city  of  Greely, 
Colorado,  a  Buckeye  Traction  digger  was  used  with  great  success.1 
The  trench  was  36  miles  long,  eight  of  it  through  a  stratum  of 
gravel  containing  many  stones,  some  of  the  gravel  cemented 
together.  The  material  in  the  rest  of  the  trench  was  clay,  rather 
hard  but  through  which  the  machine  dug  with  great  ease.  The 
trench  throughout  was  30  inches  wide  and  4^  feet  deep.  The 
description  of  the  work  allows  $6.00  per  day  for  repairs  and 
renewals,  for  interest  and  depreciation  on  the  machine,  and  the 
machine  is  said  to  have  used  on  an  average  one  ton  of  coal  per  day. 
Four  men  were  needed,  the  man  running  the  machine  receiving 
$5  per  day  and  the  other  three,  $3  each.  In  the  gravel,  the  machine 
excavated  from  600  to  1000  feet  of  trench;  while  in  the  clay  as  much 
as  2500  feet  was  dug  in  one  day  of  ten  hours.  The  cost  per  cubic 
yard  for  the  work  was  as  follows: 

Engineer $0.02 1 

Helpers 0.040 

Coal 0.021 

Plant 0.025 

$0.107 

The  author  has  been  informed  that  in  excavating  for  water 
pipes  in  the  city  of  Corning,  N.Y.,  a  Chicago  Sewer  Excavator,  of 
the  Chicago  Municipal  and  Contracting  Company  averaged  about 
600  feet  daily  through  a  hard  clay  with  many  boulders,  and  that 
the  maximum  distance  excavated  in  any  one  day  was  1200  feet,  all 
trenches  five  and  a  half  feet  deep. 

If  the  trench  is  in  rock,  the  following  items  are  to  be  considered : 
drilling,  explosives,  shoveling,  and  refilling.  Gillette  gives  the 
cost  of  hand  drilling  as  follows:  one  man  holding  and  two  men 
striking:  granite,  83  cents;  trap,  55  cents;  limestone,  38  cents,  per 
lineal  foot. 

1  Engineering-Contracting,  Vol.  29,  page  103. 


ESTIMATES  AND  COSTS  263 

The  cost  of  churn  drilling  is  given  by  Gillette  as  follows:  solid 
quartz,  55  cents;  granite,  30  cents;  limestone,  26  cents;  sandstone, 
22  cents. 

In  Engineering- Contracting  *  are  given  some  figures  of  the  cost  of 
drilling  in  open  cuts  on  the  Grand  Trunk  Pacific  Railroad.  The 
rock  encountered  was  granite,  trap,  and  diabase.  Three  men 
drilling  10  to  14  foot  holes  in  hornblende  averaged  29  lineal  feet 
per  day,  or  23  cents  per  foot,  labor  being  $2.25  per  10  hours.  In 
red  granite,  three  men  averaged  20  feet  per  day,  or  34  cents  per 
foot.  In  trap  and  diabase,  18  feet  per  day  was  the  average  rate, 
or  the  cost  was  37  cents  per  foot.  The  cost  of  sharpening  the  drills 
amounted  to  9  cents  per  foot  of  hole  drilled.  The  total  cost  there- 
fore varied  from  32  cents  to  46  cents  per  foot.  In  shallower  holes 
the  cost  of  drilling  per  foot  increased,  reaching  74  cents  per  foot 
for  shallow  block  holes  in  granite. 

In  the  same  volume2  are  given  similar  costs  for  drilling  in  sand- 
stone. Here,  as  before,  three  men  constituted  a  gang  and  the 
daily  average  varied  from  12  to  17  feet  per  day  with  the  different 
gangs.  The  entire  average  cost  of  drilling  per  lineal  foot,  including 
8J  cents  for  sharpening  drills,  was  40.3  cents. 

On  page  199  are  given  additional  values  for  the  cost  of  drilling 
into  the  mica  schist  in  New  York  City.  In  the  work  referred  to, 
15  lineal  feet  was  the  average  day's  work,  and  the  cost  of  drilling 
alone  was  40  cents  per  lineal  foot. 

If  a  steam  drill  is  available  these  costs  can  be  much  reduced, 
although  the  shallow  depth  of  the  holes  in  sewer  trenches  does  not 
bring  out  the  full  economy. 

A  steam  drill  operated  by  a  driller  and  helper  will  drill  holes  as 
follows : 3 

In  granite 45  to  50  feet  in  10  hours. 

In  mica  schist 50  to  60  feet  in  10  hours. 

In  hard  trap 40  feet  in  10  hours. 

In  red  sandstone 90  feet  in  10  hours. 

In  limestone 70  feet  in  10  hours. 

1  Engineering-Contracting,  Vol.  28,  p.  301. 

2  Engineering-Contracting,  Vol.  28,  p.  197. 

3  Gillette. 


264  SEWER  CONSTRUCTION 

The  cost  of  "operation  is  given  as  follows:1 

Driller  and  helper $4-75 

Fireman 2.00 

600  pounds  coal .90 

Water  hauled 75 

Hauling  and  sharpening  bits 1.20 

Repairs  to  drill  and  steam  piping .75 

Total  for  10  hours $10.35 

If  more  than  one  drill  is  to  be  run  by  the  same  boiler  the  cost  of 
fireman  and  coal  will  be  distributed.  But  the  rent  or  depreciation 
of  the  boiler  and  drills  should  be  added.  If  these  are  taken  at 
$3.00  per  day  the  total  cost  would  be  $13.35.  The  cost  then 
will  vary  from  14  cents  to  34  cents  per  lineal  foot,  much  less  than 
the  cost  of  hand  drilling.  In  the  open  cut  work  of  the  Grand 
Trunk  Pacific  Railroad  above  referred 'to  the  daily  expense  of 
working  one  steam  drill  from  a  boiler,  including  repairs  and  all 
incidental  expenses,  was  $14.43,  anc^  tne  average  number  of  feet 
drilled  daily  was  30,  making  a  cost,  including  sharpening,  of  48 
cents  per  foot.  If  two  drills  were  run  from  the  same  boiler,  the 
engineer  reports  that  this  amount  would  be  reduced  by  about  10 
cents  per  foot. 

The  amount  of  explosive  to  be  put  into  each  hole  varies  with  the 
depth  of  the  hole  and  the  kind  of  rock.  Estimates  are  usually 
made  on  the  basis  of  a  certain  amount  per  cubic  yard  of  rock 
loosened,  less  explosive  being  needed  per  hole  the  more  closely 
the  holes  are  drilled.  The  amount  of  40  per  cent  dynamite  needed 
per  cubic  yard  for  limestone  varies  from  one-half  to  i\  pounds  per 
cubic  yard,  the  larger  amount  being  used  in  shallow  holes  in  tough 
rock.  If  we  assume  a  trench  3  feet  wide  —  holes  staggered  on 
the  center  line  and  three  feet  deep  —  there  will  be  3  feet  of  hole 
per  cubic  yard,  costing  about  75  cents  for  drilling.  The  dynamite 
at  15  cents  a  pound  will  cost  about  20  cents,  or  95  cents  for  drilling 
and  explosive.  About  5  cents  more  should  be  added  for  placing  a 
mat  over  the  hole,  or  $1.00  per  yard  for  loosening  the  stone.  In 
throwing  the  stone  out  of  the  trench  the  amount  depends  largely 
on  the  size  of  the  pieces,  the  large  pieces  taking  a  great  deal  of  time, 

1  Gillette. 


ESTIMATES  AND  COSTS  265 

especially  if  a  bar  has  to  be  used  to  work  loose  any  separate  stones. 
One  man  ought  to  throw  out  a  cubic  yard  an  hour,  according  to 
Gillette,  although  loading  stone  into  cars  on  the  Chicago  Drainage 
Canal  required  an  hour  for  three-quarters  of  a  cubic  yard.  Not 
less  than  30  cents  per  cubic  yard  should  be  allowed  for  throwing 
out  and  about  20  cents  for  refilling,  making  the  labor  cost  50  cents. 
To  this  should  be  added  cost  of  superintendence,  office  expenses, 
and  contractor's  profit. 

The  cost  of  sheeting  is  determined  by  the  amount  of  lumber 
used,  in  the  first  instance  and  in  succession,  and  by  the  cost  of  the 
labor  for  placing  it.  It  is  seldom  worth  while  to  use  anything 
less  than  2-inch  material,  although  in  gravel,  when  little  driving 
has  to  be  done,  i-inch  stuff  can  often  be  used  to  advantage.  A 
trench  8  feet  deep  would  have,  if  close  sheeted,  the  following 
lumber  in  16  lineal  feet: 

Sheeting 2  inches  X  8  feet       X  16  feet  X  2  =  648  B.M. 

Rangers 4  inches  X  6  inches  X  16  feet  X  4  =  128  B.M. 

Braces 4  inches  X  6  inches  X    3  feet  X  6  =     36  B.M. 

Total  for  16  feet  =  812  B.M. 

or  51  feet  B.M.  per  running  foot  of  trench. 

The  cost  of  placing  lumber  of  this  sort  varies  from  $8.00  to 
$15.00  per  1000,  so  that  if  lumber  costs  $30.00  per  1,000,  the  cost 
in  place  will  be  about  $40.00  and  the  sheeting  driven  would  cost 
20  cents  per  lineal  foot;  but  the  lumber  would  be  used  two  or 
more  times  so  that  10  cents  per  lineal  foot  may  be  regarded  as  the 
minimum  cost  of  sheeting.  Larger  trenches  should  be  estimated 
in  the  same  manner,  although  in  wider  trenches  the  braces  must 
be  heavier,  10  by  12  being  sometimes  necessary.  With  care,  the 
rangers  and  braces  may  be  used  three  or  even  four  times,  but 
the  sheeting  seldom  more  than  twice.  For  comparison  the  follow- 
ing figures  are  given. 

At  Peoria,  111.,1  in  a  trench  13  feet  wide  by  45  feet  deep,  the 
labor  cost  of  sheeting  was  $3.00  per  lineal  foot  when  work  was  all 
done  by  hand,  and  $2.08  per  foot  when  steam  power  was  used  for 
driving  and  pulling  the  sheeting. 

1  Engineering  News,  Vol.  37,  p.  50. 


266  SEWER   CONSTRUCTION 

There  were  about  230  feet  B.M.  per  lineal  foot,  or  the  cost  of 
placing  and  pulling  the  sheeting  was  about  $13.00  in  the  first  case 
and  about  $9.00  in  the  second  case  per  1000  feet  B.M. 

Gillette  says  that  small  trenches  8  to  16  feet  deep  in  sand  cost 
from  10  to  25  cents  per  lineal  foot  for  labor  of  sheeting  with  2  by  8 
inch  hemlock. 

The  cost  of  excavation  in  tunnels  exceeds  and  bears  but  little 
relation  to  the  cost  of  excavation  in  open  cut.  The  laborers  work 
at  a  disadvantage,  the  cost  of  spoiling  the  material  is  large,  and  the 
cost  of  sheeting  or  timbering  is  heavy.  The  following  examples 
are  given  as  a  guide  for  estimates  of  this  kind. 

At  St.  Louis,  Mo.,  for  a  brick  sewer  30  by  42  inches,  with  9 
inches  of  brickwork,  the  cost  per  cubic  yard  was  as  follows, 1  the 
material  being  a  plastic  clay  which  would  drop  out  in  the  arch 
following  the  shovel: 

Foreman  at  50  cents $0.225 

Bottommen  at  50  cents 571 

Laborers  at  30  cents 1.946 

Carpenters  at  50  cents 359 

Labor,  timbering 161 

Timber  at  $20 381 

Watchman  at  1 7 J  cents 079 

Wasting  dirt,  585  loads  at  $i .506 

$4.228 

For  the  same  sewer  880  cubic  yards  were  in  rock  tunnel  and  the 
cost  of  this  was  given  as  follows: 

Foreman  at  50  cents $0.568 

Bottommen  at  50  cents   J-477 

Laborers  at  30  cents 3-402 

Engineer  at  50  cents 909 

Blacksmith 070 

Watchman  at  17$  cents 318 

Dynamite  at  15  cents  per  pound 682 

Caps  and  fuse 030 

Wasting  dirt,  445  loads  at  $i .500 

$7.956 

The  rock  was  a  stratified  limestone,  irregular  and  gnarly.     It 
varied  in  hardness  in  some  places  to  a  flinty  appearance.     No 

1  Engineering  Contracting,  Vol.  28,  p.  28. 


ESTIMATES  AND  COSTS  267 

charge  has  been  made  in  the  above  costs  for  plant,  coal,  oil  or 
depreciation ;  nor  are  office  expenses  or  insurance  included. 

In  Syracuse,  in  the  tunnel  sewer,  which  was  built  in  clay  rock  with 
some  slate,  most  of  which  was  thrown  down  by  blasting,  the  costs 
are  given  as  follows : *  The  entire  cost  of  the  tunnel  in  the  first  sec- 
tion was  $6.68  per  cubic  yard,  of  which  $1.67  was  for  sheeting, 
almost  equally  divided  between  labor  and  material.  The  size  of 
the  opening  was  6  feet  wide  by  7  feet  9  inches  high.  In  the  second 
section,  where  the  material  was  chiefly  a  gypsum  rock  of  a  flinty 
nature,  and  where  there  was  a  large  amount  of  water,  the  cost 
of  excavation,  exclusive  of  sheeting,  was  $7.00  per  cubic  yard, 
the  additional  cost  of  sheeting  being  $.66  for  lumber  and  $.40 
for  labor.  In  the  third  section2  the  material  was  clay  and  easily 
handled.  The  total  cost  of  excavation  is  given  as  $4.21  per  cubic 
yard,  of  which  $1.28  was  for  sheeting,  $.84  for  labor,  and  $.44  for 
material. 

In  driving  a  small  tunnel  in  Colorado,3  the  material  being  like 
ordinary  granite  and  the  size  of  the  tunnel  being  7  feet  high  by 
4.5  feet  wide,  the  costs  per  cubic  yard  were  given  as  follows: 


Sec.   i. 

Sec.  2. 

Machine  men  at  $4  

$0.0$ 

$1  .40 

^Machine  helpers  at  $3 

78 

Trammers  at  $3                                                                                        .    . 

8 

7O 

Pipe  and  track  men  at  $3                                                        

04 

.07 

Operating  machines                                        .        

.87 

.6< 

General  tramming  cost     

.02 

.02 

Explosives 

i   3? 

I     IO 

Pipe  and  track 

27 

•?r 

Hoisting                                                                                .              .... 

.48 

q7 

Supplies                                               .        .    .            

OI 

OI 

48 

r  7 

Total                                                                       

%.7? 

%44 

The  cost  of  pipe  is  determined  by  referring  to  the  list  price  issued 
by  the  Eastern  or  Western  Pipe  Manufacturing  Association  and 

1  Engineering-Contracting,  Vol.  26,  p.  139. 

2  Loc.  cit.,  page  196. 

3  Engineering-Contracting,  Vol.  26,  p.  6. 


268 


SEWER  CONSTRUCTION 


then  deducting  the  proper  discount.     The  following  are  the  list 
prices  referred  to: 


Standard  Sewer  Pipe. 

Double  Strength  Pipe. 

Diameter. 

Weight 
per  Foot. 

Price  per 
Foot. 

Diameter. 

Weight 
per  Foot. 

Price  per 
Foot. 

6 

Ibs. 

1C 

$0  .70 

Ibs. 

8 

2  3 

CQ 

28 

60 

10 

•7C 

7C. 

12 

A-l 

I    OO 

15 

60 

i-35 

15 

75 

Si  -35 

18 

85 

1.70 

18 

118 

1.70 

20 

IOO 

2.25 

20 

138 

2.25 

24 

140 

3-25 

24 

190 

3-25 

3° 

252 

5-5° 

3° 

290 

5-5° 

36 

35° 

7.00 

36 

375 

7.00 

The  discount  (1907)  is  about  75  per  cent  for  standard  pipe,  so 
that  8-inch  pipe,  for  example,  listed  at  50  cents  will  actually  cost 
I2|  cents  delivered.  If  deep  and  wide  socket  pipe  are  desired, 
the  discount  is  about  70  per  cent,  or  the  cost  per  foot  is  15  cents. 
If  double  strength  pipe  is  wanted,  the  discount  is  about  60  per  cent, 
or  the  cost  is  20  cents  per  foot.  In  estimating  the  cost  of  the  pipe 
laid,  the  cost  of  hauling  must  not  be  overlooked,  the  estimate  on 
this  being  made  by  the  distance  hauled  and  the  weight  as  given  in 
the  table.  A  team  will  walk  on  fairly  level  ground  at  the  rate  of 
2j  miles  per  hour,  not  including  time  for  loading  or  unloading, 
nor  time  taken  for  resting  or  hills,  which  in  summer  is  frequently 
extravagant.  On  a  long  hill,  for  example,  the  author  has  often  seen 
a  hired  team  take  an  hour  to  go  up  a  half-mile  hill  on  a  10  per  cent 
grade.  The  cost  of  lowering  the  pipe  into  the  trench,  placing  it 
and  packing  the  cement  into  the  joint  may  be  estimated  from 
figures  already  given  on  page  260.  The  amount  of  cement  and 
sand  needed  for  making  the  joints  can  be  determined  from  the 
following  table,1  and,  knowing  the  cost  of  both,  the  cost  of  the  joints 
is  easily  obtained. 

1  From  Engineering  News. 


ESTIMATES  AND  COSTS 


269 


-iJ 

Proportions  Based  on  Prof.  Baker's  Table  of  Material 

8, 

& 

•SI  I 

for  One  Cubic  Yard  of  Mortar,  viz.  : 

& 

"o 

£ 

•8 

1 

« 

\l\ 

a  «  J 

7.14 

6.43 

4.16   |   3.74 

0.58 

2.85 

2.57 

0.80 

rt 

5 

«i 

Ji 

"o 

"o. 

1 

s  § 

•S^i? 

Neat  Cement. 

One  Cement  to  One 
Sand. 

One  Cement  to  Two 
Sand. 

! 

.« 

!S 

H 

a 

K*     0     « 

c3  ^ 

Bbls. 
Port. 

Bbls. 
Ros. 

Bbls. 
Port. 

Bbls. 
Ros. 

Cu. 

Yds. 
Sand. 

Bbls. 
Port. 

Bbls. 
Ros. 

Cu. 

Yds. 
Sand. 

Standard. 

3 

i 

1 

1 

o  .142 

I  .01 

0.91 

0-59 

0-53 

O  .08 

0.4 

0.36 

0  .11 

4 

i 

0.174 

1.24 

I  .1 

0.7 

o-7 

0  .1 

0-5 

°-5 

0  .1 

5 

f 

o  .252 

1.8 

1.6 

I  .1 

0.9 

O  .2 

°-7 

0.7 

0  .2 

6 

1 

o  .290 

2  .1 

1.9 

I  .2 

i  .1 

0  .2 

0.8 

°-7 

0  .2 

8 

0-437 

3-i 

2.8 

1.8 

1.6 

°-3 

i-3 

i  .1 

0.4 

9 

Ji 

j 

0.514 

3.7 

3-3 

2  .1 

1.9 

°-3 

i-5 

J-3 

0.4 

10 

| 

0.618 

4.4 

4.0 

2.6 

2-3 

0.4 

1.8 

1.6 

°-5 

12 

2 

"| 

1.056 

7-5 

6.8 

4-4 

4-o 

0.6 

3-0 

2-7 

0.9 

15 

af 

1.487 

10  .6 

9.6 

6.2 

5-6 

0.9 

4-2 

3-8 

I  .2 

18 

j 

aj 

1.912 

13-7 

12.3 

8.0 

7-2 

i  .1 

5-5 

4.9 

i-5 

20 

af 

2-399 

17.1 

15-4 

10  .0 

9.0 

1-4 

6.8 

6.2 

i  .9 

24 

a| 

3-347 

23-9 

21-5 

13.9 

12  -5 

1.9 

9-5 

8.6 

2-7 

3° 

2 

3 

5-495 

39-2 

35-3 

22.9 

20  .6 

3-2 

iS-7 

14.1 

4-4 

Deep  and  Wide  Socket. 

6 

1 

af 

f 

0-585 

4-2 

3-8 

2.4 

2  .2 

°-3 

i-7 

i-5 

°-5 

8 

« 

af 

.... 

0.907 

6-5 

5-8 

3.8 

3-4 

0-5 

2.6 

2-3 

o-7 

10 

I 

al 

.... 

i  -134 

8.1 

7-3 

4.7 

4.2 

o-7 

3-2 

2-9 

o-9 

12 

I 

3 

1-594 

ii  .4 

10.3 

6.6 

6.0 

0.9 

4-5 

4-i 

1-3 

15 

if 

3f 

2.172 

J5-5 

14  .0 

9.0 

8.1 

1-3 

6.2 

5-6 

i-7 

18 

Ji 

3f 

.... 

2  .843 

20.3 

18.3 

ii  .8 

10  .6 

i-7 

8.! 

7-3 

2-3 

20 

!§ 

3l 

.... 

3.466 

24.8 

22.3 

14.4 

13-0 

2  .O 

9-9 

8.9 

2.8 

24 

If 

4 



4-797 

34-3 

30.8 

20  .O 

17.9 

2.8 

13-7 

12.3 

3-8 

Double  Strength. 

IS 

i} 

a} 

\ 

1.796 

12.8 

ii.  6 

7-5 

6-7 

I  .0 

5-i 

4-6 

1-4 

18 

l| 

af 

2.499 

17.8 

16.1 

10.4 

9-4 

I  .5 

7-i 

6.4 

2  .0 

20 

!§ 

3 

.... 

3.162 

22.6 

20.3 

13.2 

ii.  8 

i  .8 

9.0 

8.1 

2  .5 

24 

2 

3i 

.... 

4.801 

34-3 

3°  -9 

20  .0 

18.0 

2.8 

13-7 

12.3 

3-8 

3° 

a* 

4 

| 

9-095 

64.9 

58.5 

37-8 

34-0 

5-3 

25-9 

23.4 

7-3 

B.  &  P.  Standard. 

27 

aj 

4 

| 

7.847 

56.0 

5°-5 

32.6 

29.4 

4-6 

22  .4 

2O  .2 

6-3 

3° 

af 

4 

£ 

10.183 

72.7 

65-5 

42.4 

38.1 

5-9 

29  .0 

26.2 

8.2 

33 

a) 

4i 

I 

13  -541 

96.7 

87.1 

56.3 

50  .6 

7-9 

38.6 

34-8 

10.8 

36 

a| 

5 

I 

1  6  .007 

174.3 

102  .9 

66.6 

59-9 

9-3 

45-6 

41  .1 

12.8 

B.   &  P.   Double  Strength. 

27 

af 

4 

J 

8-333 

59-5 

53-6 

34-7 

31.2 

4.8 

23-8 

24-4 

6-7 

3° 

aj 

4 

| 

11  -371 

81.2 

73  -1 

47-3 

42.5 

6.6 

32-4 

29.2 

9.1 

33 

aj 

4i 

I 

14  -943 

106.7 

96  .1 

62.2 

55-9 

8-7 

42  .6 

38.4 

12  .0 

36 

af 

5 

I 

'7-57I 

125-5 

113.0 

73-i 

65-7 

IO  .2 

50.1 

45-2 

I4.I 

2/0  SEWER   CONSTRUCTION 

The  cost  of  brickwork  in  sewer  construction  must  be  esti- 
mated from  the  unit  prices  of  the  material  and  labor,  the  amount 
of  brickwork  per  lineal  foot  of  sewer  having  already  been  given 
on  page  34.  The  cost  of  brick  runs  from  $8.00  to  $12.00  per 
thousand  for  ordinary  building  brick,  and  from  $16.00  to  $20.00 
per  thousand  for  paving  brick.  They  must  be  hauled  to  the 
sewer,  1000  brick  being  a  load  on  level  ground  over  good  roads, 
and  500  brick  a  load  on  average  dirt  roads.  The  added  cost  per 
thousand,  therefore,  on  a  dirt  road  is  about  80  cents  per  mile  of 
haul,  to  which  should  be  added  the  time  lost  on  each  trip  while 
waiting  for  loading  and  unloading  —  or  50  cents  more  —  if  the 
wait  is  half  an  hour  at  each  end  and  the  haul  is  a  mile.  In  lay- 
ing, a  good  sewer-brick  mason  will  lay  2000  to  3000  brick  in  8 
hours,  instead  of  about  a  thousand  as  in  house-laying.  Gillette 
notes  a  case  of  a  man  laying  600  brick  an  hour,  but  this  is  too 
many  for  an  average  or  an  estimate. 

From  three-tenths  to  four-tenths  of  a  cubic  yard  of  mortar  are 
needed  for  each  cubic  yard  of  brickwork,  and  the  materials  needed 
for  each  yard  of  mortar  are  given  in  the  table  on  page  269. 1 

The  cost  of  cement  and  of  sand  will  vary  in  different  places, 
and  would  be  locally  determined  in  preparing  an  estimate  as  fol- 
lows, the  supposed  sewer  being  4  feet  diameter,  two  rings  thick: 

Brick  —  4  feet  dia.  2  ring  at  .415  cubic  yard  per  foot  X  $10.00  =      $5.00 
Hauling,  $1.30  per  500  brick,  or  i  cubic  yard  =  1.08 

Mortar  .17  cubic  yard  requires 

.39  barrel  cement  at  $2.00 $0.78 

.17  cubic  yard  sand  at  $1.00 17 

-95 

Labor  fc  day  of  mason  at  $4.80 96 

Labor  $  day  of  helper  at    1.75 70 

1.66 

Centers  cost  of  100  feet  used  ten  times,  $120.00,  or  about 

12  cents  per  foot  -15 

Total  cost  per  cubic  yard  =  8.84 

Total  cost  per  lineal  foot  =  $8.84  X  f&2  =  7-34 

In  shallow  trenches  two  laborers  may  be  able  to  supply  two 
masons,  or  three  laborers  may  supply  two  masons,  but  it  is  always 
wise  to  estimate  for  and  expect  a  large  number  of  helpers  in  sewer 

1  See  also  Baker's  "Masonry  Construction." 


ESTIMATES  AND   COSTS 

work.  The  brick  have  to  be  lowered  by  hand  and  often  carried 
by  hand  in  the  bottom  of  the  trench.  The  mortar  board  has  to 
be  frequently  shifted  and  its  position  is  usually  hard  to  reach,  and 
since  the  mason  should  not  be  expected  to  stop  his  work,  it  is 
necessary  to  provide  helpers  in  abundance. 

A  small  brick  egg-shaped  sewer  was  built  in  Worcester,  Mass.,  in 
1905  1  in  a  trench  whose  average  depth  was  9.8  feet.  The  soil  was 
gravel,  and  tight  sheeting  was  used  throughout.  The  invert  of 
the  sewer  was  8-inch  brickwork  and  the  arch  was  4-inch  work, 
plastered  outside  with  a  i-inch  coat  of  cement  mortar.  The  brick 
cost  $9.20  per  1000  and  the  cement  $1.55  to  $1.75  per  barrel;  the 
masons  were  paid  70  cents  per  hour  and  the  helpers  30  cents. 
There  were  57,200  brick  used,  and  the  total  cost  of  masons  and 
helpers  was  $375.20,  or  $6.56  per  1000  brick,  equivalent  to  $3.33 
per  cubic  yard  of  brickwork. 

At  St.  Louis,  in  1906-1907,  a  30-inch  by  42-inch  brick  sewer 
was  built  in  I3th  Street.2  The  work  was  in  tunnel  and  the  cost  of 
the  brickwork  might  be  expected  to  be  greater  than  at  Worcester; 
it  was,  in  fact,  considerably  less.  The  thickness  of  the  ring  was 
9  inches,  and  some  additional  brickwork  was  used  to  fill  in  the  open 
spaces  above  the  arch.  The  brick  cost  $9.00  per  1000  and  the 
cement  $1.80  per  barrel;  the  masons  were  paid  $1.00  per  hour 
and  the  helpers  30  cents.  There  were  340,000  brick  used  and  the 
total  cost  of  masons  and  helpers  was  $1900.00,  or  $5.58  per  1000 
brick,  equivalent  to  $2.46  per  cubic  yard  of  brickwork.  The 
cost  of  the  masonry  complete  was  given  as  $7.99  per  cubic 
yard. 

The  cost  of  concrete  in  sewer  work  is  high  because  it  is  often 
difficult  to  place  and  because,  in  thin  layers,  the  cost  of  forms 
and  finishing  is  a  large  proportion  of  the  total.  The  cost 
of  materials  and  the  labor  cost  of  mixing  are  easily  estimated, 
the  amount  of  each  ingredient  being  computed  separately  as 
follows : 

Assume  a  i  :  2  :  5  concrete  —  cement  at  $2.00  per  barrel,  sand 

1  Engineering-Contracting,  Vol.  27,  p.  28. 

2  Engineering-Contracting,  Vol.  28,  p.  28. 


2/2  SEWER   CONSTRUCTION 

at  Si. oo  per  cubic  yard,  and  broken  stone  at  $1.50  per  cubic  yard. 
The  cost  per  cubic  yard  of  concrete  then  is : 

1.3  barrels  cement  at  $2.00 $2.60 

.36  cubic  yard  sand  at  $1.00 36 

.90  cubic  yard  stone  at  $1.50 1.35 

Mixing  the  concrete  by  hand 75 


$5.06 

This  is  a  fair  price  for  the  concrete  mixed  and  ready  to  be  put 
in  place.  If  gravel  and  sand  are  used,  in  the  same  combination  in 
which  they  come  from  the  bank,  the  cost  of  sand  and  stone,  $1.71, 
may,  under  favorable  conditions,  be  cut  in  two,  reducing  the  cost 
of  the  mixed  concrete  to  $4.20.  If  a  mixing  machine  is  used  the 
cost  of  mixing  per  cubic  yard  may  be  as  little  as  5  cents,  with 
10  cents  added  for  interest  and  depreciation,  making  the  cost 
of  the  gravel  concrete,  machine  mixed,  $3.60  per  cubic  yard. 
The  cost  of  carrying  the  concrete  to  the  place  where  it  is  required, 
the  cost  of  ramming  into  place,  and  the  costs  of  forms  are  uncertain 
and  difficult  to  estimate,  although  they  form  a  large  part  of  the 
total  cost  of  the  concrete. 

Shoveling  l  into  wheelbarrows  will  cost  16  cents  per  cubic  yard. 
The  cost  of  wheeling  is  i  cent  for  every  25  feet  +  4  cents  for  lost 
time,  or  21  cents  if  the  haul  is  25  feet  and  24  cents  for  100  feet. 

Dumping  down  a  chute  which  has  to  be  frequently  moved  will 
cost  at  least  8  cents  per  cubic  yard,  and  additional  shoveling  of  the 
concrete  at  the  foot  of  the  chute  will  cost  10  cents  per  cubic  yard, 
adding  to  the  cost  given  above  of  $5.06,  42  cents,  or  a  total  of 
$5.48  for  the  concrete  in  place,  a  cost  which  may  be  modified  in 
the  several  items  by  the  judgment  of  the  engineer. 

The  cost  of  forms  is  largely  influenced  by  the  cleverness  of  the 
constructor.  If  the  ground  is  stable  there  need  be  no  forms  for 
the  invert,  only  frames  for  the  screed  boards  every  8  feet.  The 
centers  for  the  arch  can  be  used  over  and  over,  and  it  is  necessary 
to  build  enough  to  last  for  that  time  during  which  the  arch  must 
be  supported,  usually  a  length  equal  to  two  days'  work.  The 

1  These  estimates  are  taken  from  Gillette. 


ESTIMATES  AND  COSTS  273 

quantity  of  lumber  needed  may  be  computed  at  the  local  price  per 
1000,  with  about  $10.00  per  1000  added  for  carpenter  work. 

At  Wilmington,  Del.,  the  cost  of  forms  for  a  concrete-steel 
sewer,  ranging  from  9  feet  3  inches  to  6  feet  6  inches  radius,  through 
the  1800  lineal  feet  of  sewer,  was  8.2  cents  per  cubic  yard  of  con- 
crete laid,  and  the  cost  of  setting  the  forms  was  4.5  cents  per  cubic 
yard,  or  a  total  of  only  12.7  cents  per  cubic  yard,  a  very  small 
amount. 

In  building  a  5 -foot  concrete  steel  conduit  near  Newark,  N.J., 
the  cost  of  labor  in  merely  moving  the  forms  is  given  at  60  cents 
per  cubic  yard.  If  no  outside  forms  are  used  on  the  arch,  a  good 
deal  of  material  is  often  wasted  by  having  the  thickness  greater 
than  was  intended,  so  that  it  may  be  cheaper  to  provide  some 
outside  forms  even  if  these  are  only  boards  held  out  from  the  sides 
of  the  trench  by  stakes  or  props. 

In  the  construction  of  the  Harlem  Creek  sewer  in  St.  Louis,  in 
I906,1  about  1600  cubic  yards  of  concrete  were  used  in  connection 
with  43  tons  of  steel  rods.  The  sewer  is  29  feet  wide  by  18.6  feet 
high  and  the  thickness  of  the  arch  ring  is  thirty  inches.  The 
concrete  was  cement,  sand,  and  broken  limestone  in  the  pro- 
portions of  i  :  3  :  6  for  the  invert  and  1:2:5  f°r  tne  arch. 
It  was  machine  mixed  in  cube  mixers.  The  cement  cost 
$1.80  per  barrel,  the  sand  $0.75  per  cubic  yard,  the  broken  stone 
$1.00  per  cubic  yard,  and  the  steel  2  cents  per  pound.  Wages  ran 
from  17.5  cents  for  the  poorest  to  30  cents  for  the  best  labor  per 
hour.  The  cost  of  the  concrete  per  cubic  yard  was  as  follows: 

1.30  barrels  cement  at  $1.80 $2.34 

0.44  cubic  yard  sand  at  75  cents 33 

i  cubic  yard  broken  stone  at  $i i.oo 

55  pounds  steel  at  2  cents i.io 

Mixing  and  placing  concrete 74 

Forms,  labor  and  material 1.25 

Placing  steel  at  0.2  cent  per  pound n 

Bending  steel  at  0.06  cent  per  pound 03 

Moving  forms 25 

$7-i5 
1  Engineering-Contracting,  Vol.  27,  p.  76. 


274  SEWER   CONSTRUCTION 

The  figures  given  do  not  include  interest  or  depreciation  on  the 
extensive  plant  which  was  installed  nor  the  cost  of  running  the 
plant.  The  latter  item  was  $2000  for  this  part  of  the  work,  or  $1.25 
per  cubic  yard  if  this  cost  is  distributed  over  the  1600  yards.  This 
is  not  accurate,  however,  as  the  plant  was  used  for  purposes  of 
excavation  as  well  as  for  building  the  masonry. 

At  South  Bend,  Ind.,  where  a  half  mile  of  66-inch  reinforced 
concrete  sewer  was  built  in  1906,  already  described  on  page  85, 
the  concrete  was  made  with  gravel  and  mixed  in  a  Smith  mixer.1 
The  disposition  of  the  force  of  men  mixing  and  placing  concrete 
and  the  wages  were  as  follows: 

Six  wheelers  at  18.5  cents  per  hour. 
One  mixer  at  22.5  cents  per  hour. 
One  dumper  at  18.5  cents  per  hour. 
Four  placers  at  22.5  cents  per  hour. 

The  cost  of  the  concrete  per  cubic  yard  was  given  as  follows: 

Cost  of  — 

gravel $0.774 

sand 36 

cement 1.50 

steel  rods 84 

labor,  placing  and  mixing  concrete 1.094 

forms,  templates,  etc 589 

moving  forms,  templates,  etc 757 

finishing,  plastering,  etc 639 

tools  and  general  expenses .841 

$7-395 

During  the  summer  of  1906,  Mr.  O.  P.  Chamberlain  built  a 
number  of  concrete  culverts,  using  4  foot  concrete  pipes  molded 
in  the  form  of  hollow  cylinders  with  square  ends.  The  pipes  were 
6  inches  thick  and  were  made  of  limestone  screenings  and  crushed 
limestone  that  had  passed  through  a  f -inch  screen  and  was  caught 
on  a  J-inch  screen.  The  forms  were  of  wood,  the  inner  form 
having  a  wedge-shaped  loose  stave  which  could  be  withdrawn  after 
the  concrete  had  set.  The  outer  form  was  in  two  parts,  held 
together  by  pins  which  could  be  removed  to  separate  the  forms.2 

1  Engineering-Contracting,  Vol.  26,  p.  49. 

2  Engineering-Contracting,  Vol.  27,  p.  68. 


ESTIMATES  AND   COSTS  275 

Mr.  Chamberlain  estimates  the  cost  of  molding  the  four-foot  pipes 
as  follows: 

Depreciation  of  forms,  2  per  cent  of  $40 • $0.80 

i.i  cubic  yards  stone  and  screenings  at  $1.85 2.04 

0.8  barrel  cement  at  $2.10 1.68 

10  hours  labor  at  28  cents 2.80 

$7-32 

There  were  1.05  cubic  yards  per  length  of  pipe,  or  the  cost  of  con- 
crete molded  in  the  form  of  pipe  was  $7.00  per  cubic  yard. 

The  cost  of  manholes  must  be  estimated  from  the  separate 
parts.  It  takes  a  yard  of  concrete  for  the  bottom,  i.e.,  a  barrel  and 
a  third  of  cement,  or  usually  five  bags,  a  yard  of  broken  stone, 
and  a  half  yard  of  sand,  or  a  yard  of  gravel  containing  the  proper 
amount  of  sand.  The  brick  side  walls  are  laid  by  a  mason  who 
ought  to  lay  1000  brick  in  a  day  of  8  hours,  a  manhole  containing 
about  175  brick  in  each  vertical  foot  or  1000  brick  for  6  feet 
depth.  The  brick,  mortar,  and  labor  make  the  cost  of  the  brick- 
work in  a  6-foot  manhole  about  $16.00,  and  the  frame  and  cover 
will  cost  from  if  cents  to  3  cents  per  pound,  or  about  $8.00.  The 
total  cost  then  is,  for  a  6-foot  manhole,  approximately: 

Bottom $  4.00 

Sides 16.00 

Cover 8.00 

$28.00 

For  deeper  manholes  add  $3.00  per  lineal  foot  of  depth  greater 
than  6  feet. 

The  cost  of  cast  iron  and  steel  is  usually  estimated  at  a  certain 
price  per  pound,  the  cost  of  shop  work  being  added  to  the  cost  of 
the  raw  material.  Pig  iron  is  quoted  at  about  $20.00  per  ton,  and 
any  foundry  has  always  to  meet  that  cost  plus  the  cost  of  the  labor 
put  on  the  castings.  The  cost  of  the  latter  depends  on  the  cost 
of  the  pattern  in  proportion  to  the  cost  of  the  castings,  on  the  size 
and  weight  of  each  separate  casting,  and  on  the  intricacy  or  sim- 
plicity of  the  casting  itself.  For  example,  the  patterns  for  a  cast- 
iron  gate  might  easily  cost,  for  labor  alone,  $25,  while  the  gate 


276  SEWER  CONSTRUCTION 

itself  might  weigh  only  150  pounds  and  cost  about  $5.00.  The 
apparent  cost  of  the  iron  involved,  therefore,  would  be  the  quotient 
of  25  plus  5,  or  30,  divided  by  150,  or  20  cents  per  pound.  Patterns 
for  single  castings,  therefore,  ought  to  be  avoided  in  the  interests 
of  economy,  and  where  required  the  design  should  be  very  simple, 
without  curved  lines  or  surfaces  and  the  pattern  adapted  to  rapid 
carpenter  work. 

Then  again  the  cost  of  molding  per  pound  is  less  on  large, 
heavy  castings  than  on  small  and  light  ones.  The  hand  labor 
involved  in  repeated  moldings  of  a  small  casting  of  one  pound, 
making  up  one  ton,  for  example,  is  much  greater  than  in  a  single 
length  of  water  pipe  which  weighs  a  ton  in  one  piece.  Again,  a 
simple  rectangular  solid  can  be  molded  more  quickly  and  cheaply 
than  a  complicated  assemblage  of  pieces  requiring  cores  to  be 
made  and  several  flasks  to  be  used  to  form  the  required  casting. 
All  these  points,  as  well  as  the  degree  of  finish  called  for,  affect 
the  cost  per  pound,  and  the  estimated  cost  of  the  finished  casting 
will  vary  between  2  cents  per  pound  on  large  orders  of  simple  cast- 
ings to  10  cents,  or  even  20  cents  per  pound,  on  single  and  elaborate 
castings.  This  does  not  include  machine  finishing,  which  must  be 
liberally  allowed  for  in  the  time  of  the  machinist  at  50  cents  per 
hour.  The  ordinary  price  for  manhole  covers  varies  from  2  to 
4  cents  per  pound,  depending  on  the  size  of  the  order,  the  form  of 
the  section,  and  the  finish  required. 

Cast  iron  in  the  form  of  pipes  costs  about  2  cents  per  pound 
delivered  at  the  work.  But  the  current  price  of  pipe  should  always 
be  looked  up  (Engineering  News  publishes  the  current  prices  of 
steel  and  iron  regularly  each  month),  and  the  cost  of  freight, 
hauling  and  laying  added. 

Trautwine  gives  careful  analyses  of  the  cost  of  laying  cast  iron 
pipe,  as  does  also  Gillette,  to  whom  the  reader  is  referred  for 
greater  detail. 

The  cost  of  steel  used  in  concrete  reinforcement  should  also  be 
carefully  investigated  for  each  estimate.  Its  cost  is  usually  not 
far  from  2  cents  per  pound  delivered  at  the  work,  and  the  cost  of 
placing  is  to  be  added.  Expanded  metal  is  sold  by  the  square 


ESTIMATES  AND  COSTS 


277 


foot,  and  the  same  necessity  for  market  quotations  exists  in  this 
case.  Five  cents  per  square  foot  will  ordinarily  pay  for  and  place 
this  material. 

The  cost  of  flush  tanks  should  be  divided  into  the  cost  of  the 
manhole  and  the  cost  of  the  discharging  apparatus.  The  cost  of 
the  manhole  has  already  been  discussed.  The  cost  of  the  Miller 
Automatic  Siphon,  which  may  be  taken  as  a  fair  type  of  discharg- 
ing apparatus,  is  given  in  the  following  table,  about  20  per  cent 
discount  being  allowed  (1906). 


Size  and  Capacity  of  Tanks. 

Water  Re- 

Price f.  o.  b. 

Diameter 
of  Siphon, 
Inches. 

of  Sewer, 
Inches. 

Diameter, 
Feet. 

Discharg- 
ing Depth, 

Discharg- 
ing Ca- 
pacity, 

quired  to  Fill 
100  Lineal 
Feet  of  Sewer, 
Cubic  Feet. 

Chicago, 
Siphons  of 
Standard 
Length. 

Cubic  Feet. 

3 

4-  6 

2 

18 

4-5 

8.7-    20 

$20  .00 

5 

6-  8 

4 

28 

25 

20~  35 

26  .00 

6 

8-10 

4* 

37 

42 

35-  55 

30  .00 

8 

12-15 

5 

42 

65 

80-122 

40  .00 

The  cost  of  a  flush  tank,  therefore,  equipped  with  a  Miller  siphon 
and  proper  water  connection,  will  be  from  $50.00  upward.  If  the 
flush  tank  is  fitted  with  a  water  supply  faucet  and  a  flap  valve  to 
be  operated  by  hand,  this  cost  may  be  reduced  to  about  $10.00 
more  than  the  cost  of  the  manhole. 

The  amount  of  the  contractor's  profit  should  be  added  in  making 
the  estimate,  and  also  a  sum  for  contingencies.  The  percentage 
for  profit  ought  to  be  different  on  material  and  on  labor.  If  the 
contract  is  a  large  one,  involving  a  large  amount  of  material,  and 
but  little  labor  to  place  it,  as,  for  example,  where  the  pipe  are 
estimated  separately,  a  profit  of  from  5  per  cent  to  10  per  cent  is 
proper  and  ample.  But  when  the  contract  is  for  labor  alone,  as 
in  trenching,  the  percentage  ought  to  be  not  less  than  15  per  cent, 
and  with  uncertain  ground  even  more  than  this.  Contingencies 
are  usually  estimated  at  a  certain  percentage  of  the  entire  estimate, 
although  it  is  more  reasonable  to  base  the  contingencies  on  that 
part  of  the  work  only  where  contingencies  may  arise.  Ten  per  cent 


278  SEWER  CONSTRUCTION 

is  an  average  percentage  for  the  purpose,  being  less  when  the 
conditions  are  certainly  known  and  more  when  uncertainties  of 
soil,  of  water,  and  of  weather  will  seriously  affect  the  cost  of  the 
work. 

The  cost  of  engineering  is  difficult  to  predict.  About  6  per  cent 
of  the  estimated  cost  of  the  work  is  commonly  supposed  to  cover 
the  cost  of  necessary  surveys,  design,  superintendence,  and  con- 
struction. With  a  sewer  system  costing  $100,000  the  $6,000,  or 
6  per  cent,  would  then  be  divided  up  as  follows: 

Surveys  and  maps  —  25  miles  of  street  at  $30 $  750.00 

Design,  including  detail  plans 1500.00 

General  superintendence 2000.00 

Inspection  and  office  work 1750.00 

$6000.00 


CHAPTER  XIX. 
CONTRACT  AND   SPECIFICATIONS. 

SIDE  by  side  with  the  preparation  of  the  detail  plans  should  go 
the  drawing  up  of  the  specifications,  which  are  the  verbal  descrip- 
tion of  the  plans,  and  along  with  the  construction  of  the  work 
must  go  the  interpretation  and  application  of  those  specifica- 
tions. Much  has  been  written  on  this  subject,  and  Johnson's 
"Specifications"  or  Wait's  " Engineering  Jurisprudence"  or 
Waddell  and  Wait's  "Specifications  and  Contracts"  may  be 
referred  to  for  detailed  discussion  of  the  various  questions  which 
may  arise  both  as  to  the  form  of  the  contract  and  specification 
clauses  and  as  to  their  effect  upon  the  progress  of  the  work 
which  they  control.  There  is  a  growing  tendency  to  make 
specification  clauses  more  definite  and  to  give  up  the  time-hon- 
ored phrase,  so  comforting  to  the  engineer  who  was  preparing 
to  direct  work  of  the  details  of  which  he  knew  little  or  nothing, 
that  the  work  was  to  be  done  "according  to  the  satisfaction  of 
the  engineer."  A  capable  engineer  knows  before  the  work 
begins  exactly  what  he  wishes  and  how  the  work  should  be 
done,  and  the  substitution  of  exact  definition  for  the  former 
uncertainty  is  certainly  desirable.  One  exception  is  made  when- 
ever the  contract  is  designed  to  allow  the  contractor  full  liberty 
of  method  and  material  so  long  as  the  results  desired  are 
gained,  and  then  the  result  must  be  properly  obtained  to  the 
satisfaction  of  the  engineer. 

The  form  of  contract  and  specification  following  is  one  that 
has  been  used  by  the  author  for  several  pieces  of  work  and 
which  has  stood  the  test  of  dishonest  contractors  and  of  unrea- 
sonable lawsuits.  It  is  not  perfect,  as  the  author  himself  recog- 
nizes and  as  he  has  indicated  by  some  of  the  comments,  but  it 
will  serve  as  a  guide  to  the  inexperienced  engineer  who  is  under- 
taking for  the  first  time  to  prepare  such  a  document  for  work 

279 


280  SEWER   CONSTRUCTION 

under  his  direction.  It  would  be  wise,  after  it  has  been  carefully 
written  out,  to  have  it  submitted  first  to  a  local  attorney  to  be 
sure  that  it  conforms  to  all  the  local  legal  requirements,  and  second 
to  a  competent  engineer  experienced  in  municipal  or  sanitary 
work.  Each  clause  should  be  carefully  scrutinized  before  its 
incorporation  to  make  sure  that  it  applies  to  the  work  in  hand, 
that  it  will  secure  just  the  results  desired,  and  that  it  conforms 
to  local  usage.  The  specific  items  for  the  contractor's  unit  prices 
are  not  given  and  care  must  be  taken  that  none  be  omitted  from 
Section  O,  and  the  specification  clauses  should  be  carefully 
compared  with  those  items  to  make  sure  that  the  description  of 
each  item  is  incorporated  in  the  specifications. 

CONTRACT   AND    SPECIFICATIONS. 

FOR  BUILDING  SECTION OF  THE  SEWERAGE  SYSTEM  OF  THE 

CITY  OF  -  — ,  — , 

THIS  AGREEMENT,  made  and  entered  into  this 

day  of in  the  year  one  thousand  nine  hundred 

and ,  by  and  between  the  Board  of  Sewer  Commis- 
sioners of  the  City  of ,  party  of  the  first  part,  and 


party. ...  of  the  second  part, 

WITNESSETH,  That  the  parties  to  these  presents,  each  in  consider- 
ation of  the  undertakings,  promises,  and  agreements  on  the  part  of  the 
other  herein  contained,  have  undertaken,  promised  and  agreed,  and 
do  hereby  undertake,  promise  and  agree,  the  party  of  the  first  part,  for 
themselves,  their  successors  and  assigns,  and  the  party. ..  .of  the 

second  part ....  for and heirs,  executors  and 

administrators  as  follows: 

This  introductory  clause  is  the  legal  form  which  is  generally 
used.  The  "party  of  the  first  part"  is  conventionally  applied 
to  the  person  who  contracts  to  have  performed  the  subject- 
matter  of  the  contract,  and  "  the  party  of  the  second  part "  is 
applied  to  the  person  agreeing  to  perform  the  contract.  These 
terms  are  frequently  omitted  and  in  the  body  of  the  contract 


CONTRACT  AND  SPECIFICATIONS  281 

the  names  or  titles  of  the  parties  are  substituted,  or  reference  is 
made  by  such  terms  as  "  said  contractor/7  "  said  city,"  etc. 

The  word  "  assigns "  should  be  omitted  if  the  contract  con- 
tains a  clause  prohibiting  an  assignment,  or  if  the  contract  is 
for  special  work  in  the  successful  prosecution  of  which  the 
personal  skill  and  experience  of  the  contractor  are  considered 
essential. 

That  whenever  and  wherever  in  this  agreement  the  word  "Board" 
or  a  pronoun  in  the  place  of  it  is  used,  the  same  is  understood  to  refer 

to  the  Board  of  Sewer  Commissioners  of  the  City  of ,  and 

refers  to  and  designates  the  parties  of  the  first  part  to  this  agreement. 

That  whenever  the  word  "Engineer"  is  used  in  these  specifications 
or  in  this  contract,  it  refers  to  the  Engineer  employed  by  the  Board  for 
the  special  purpose  of  directing  and  having  in  charge  the  work,  the 
said  Engineer  acting  either  directly  or  through  any  assistant  or 
inspector  in  immediate  charge  of  a  portion  of  the  work,  limited  by  the 
particular  duties  intrusted  to  him. 

That  whenever  the  word  "  Contractor  "  or  a  pronoun  in  the  place 
of  it  is  used,  the  same  shall  be  taken  and  deemed  to  mean  and 
intend  the  party  or  parties  of  the  second  part  to  this  agreement. 

These  three  clauses  are  generally  inserted,  it  being  considered 
prudent  to  explain  who  is  intended  to  be  included  within  the 
terms. 

A.  The  Contractor  shall  at  his  own  cost  and  expense,  and  in  direct 
conformity  to  the  hereinafter  contained  specifications,  furnish  all  the 
materials  as  specified,  and  all  labor  necessary  or  proper  for  the  pur- 
poses; and  in  a  good,  substantial,  and  workmanlike  manner,  construct 

Section of  the  Sewerage  system  of  the  City  of do  all 

earth,  rock,  and  lumber  work,  construct  all  masonry,  build  in,  or  in 
connection  with  said  masonry,  all  iron,  timber  and  other  work  required 
or  ordered  to  be  so  built,  lay  all  pipes  and  iron  work,  and  do  all  work 
necessary  for  taking  care  of  any  water  that  may  interfere  with  the 
operations  of  construction,  and  do  all  work  necessary  to  construct  the 
said  work  in  accordance  with  the  plans  in  the  manner  and  under  the 
conditions  herein  specified. 

This  is  a  general  clause  summarizing  the  work  to  be  done. 
It  should  clearly  state  what  is  expected  of  the  contractor  and 
should  indicate  what  material,  if  any,  is  to  be  furnished  by  the 


282  SEWER  CONSTRUCTION 

party  of  the  first  part.     The  paragraph  given  above  is  unusu- 
ally condensed. 

B.  To  prevent  all  dispute  and  litigation,  it  is  further  agreed  by  and 
between  the  parties  to  this  contract  that  the  Engineer  shall  in  all  cases 
determine  the  amount  or  quality  of  the  several  kinds  of  work  which  are 
to  be  paid  for  under  the  contract,  and  he  shall  determine  all  questions 
in  relation  to  said  work  and  the  construction  thereof;  he  shall,  in  all 
cases,  determine  every  question  which  may  arise  relative  to  the  fulfill- 
ment of  this  contract  on  the  part  of  said  Contractor;  and  his  estimate 
and  decision  shall  be  final  and  conclusive  upon  said  Contractor;  and 
in  case  any  question  shall  arise  between  the  parties  hereto,  touching 
this  contract,  such  estimate  and  decision  shall  be  a  condition  precedent 
to  the  right  of  the  Contractor  to  receive  any  money  under  this  agree- 
ment. 

This  clause,  or  a  similar  one,  is  invariably  found  in  engineer- 
ing contracts,  although,  of  late  years  particularly,  much  oppo- 
sition to  the  clause  has  been  expressed.1  The  courts  are  not 
fully  agreed  upon  what  ground  to  support  it,  and  in  some 
exceptional  cases  whether  to  support  it  at  all.  The  clause  does 
not  prevent  the  contractor  from  applying  to  the  courts  for  relief 
if  he  believes  that  the  engineer  has  acted  dishonestly  or  has 
been  guilty  of  gross  mistakes.  The  courts  are  inclined  to  require 
the  engineer's  estimate  and  certificate  before  taking  up  the 
question  of  his  accuracy  and  honesty,  and  the  United  States 
courts  have  held  that  slight  errors  in  an  engineer's  estimates 
are  not  sufficient  to  imply  fraud  or  bad  faith,  and  that  his  esti- 
mate is  conclusive  upon  questions  of  count,  measurement,  or 
distance,  provided  he  has  exercised  an  honest  judgment.  In 
spite  of  the  apparently  one-sided  character  of  this  clause,  making 
the  agent  of  one  party  the  umpire  for  both,  the  clause, 
through  the  sense  of  fair  dealing  which  most  engineers  have, 
seldom  works  harm;  occasionally  there  is  an  instance  of 
outrageous  wrong  under  its  authority. 

C.  And  it  is  further  agreed  by  the  parties  to  this  agreement  that 
whenever  the  Engineer  aforesaid  shall  be  unable  to  act,  in  consequence 

1  Trans.  Am.  Soc.  C.  E.,  Vol.  58,  p.  345  et  seq.,  p.  380. 


CONTRACT  AND   SPECIFICATIONS  283 

of  absence  or  other  cause,  then  such  other  Engineer  or  assistant  as  the 
Board  of  Sewer  Commissioners  shall  designate,  shall  perform  all  the 
duties  and  be  vested  with  all  the  power  herein  given  to  said  Engineer. 

There  are  certain  duties  which  the  engineer  of  a  company 
cannot  delegate,  especially  if  the  work  is  of  considerable  impor- 
tance and  magnitude  and  the  engineer  has  been  selected  with 
special  reference  to  his  personal  skill,  judgment,  or  discretion. 
Such  work  as  drafting,  setting  grade  stakes,  or  other  mechanical 
work  may  properly  be  assigned  to  assistants,  custom  permitting 
it  and  no  special  judgment  being  exercised,  but  the  higher 
engineering  functions,  properly  called  judicial  acts,  cannot  be 
delegated. 

D.  It  is  expressly  understood  and  mutually  agreed  by  the  parties 
hereto  that  the  quantities  of  the  various  classes  of  work  to  be  done  and 
materials  to  be  furnished  under  this  agreement,  which  have  been 
estimated  as  stated  in  the  proposal  of  this  work,  are  approximate, 
and  only  for  the  purposes  of  comparing  on  a  uniform  basis  the  bids 
offered  for  the  work;  and  the  Contractor  further  agrees  that  neither 
the  City  nor  the  Board  is  to  be  held  responsible  that  any  of  the  said 
estimated  quantities  be  found  even  approximately  correct  in  the  con- 
struction of  the  work;  and  that  the  said  Contractor  will  make  no 
claim  for  anticipated  profits,  or  for  loss  of  profit,  because  of  difference 
between  the  quantities  of  the  various  classes  of  work  actually  done,  or 
of  materials  actually  delivered,  and  the  quantities  stated  in  the  bids, 
and  the  Contractor  hereby  undertakes  and  agrees  that  he  will  complete 
the  entire  work  to  the  satisfaction  of  the  Board  and  in  accordance 
with  the  specifications  and  plans  herein  mentioned  at  the  prices 
herein  agreed  upon  and  fixed  therefor. 

When  an  erroneous  preliminary  estimate  has  been  made  by 
an  engineer,  and  when  the  contractor  has  based  his  proposal 
on  such  an  estimate,  thereby  being  put  to  additional  expense, 
it  would  seem  in  justice  as  if  the  company  represented  by  the 
engineer  should  bear  the  additional  expense.  To  avoid  this, 
however,  the  clause  given  is  inserted,  under  which  the  con- 
tractor must  be  assumed  to  take  all  risk  of  the  quantities  turning 
out  larger  than  the  engineer  had  represented.  When  payment 
is  made  on  a  unit  price  basis,  and  where  the  bids  on  the  separate 


284  SEWER   CONSTRUCTION 

items  represent  fair  values  for  the  work,  the  interpretation  of 
this  clause  is  not  often  questioned.  Statements  of  quality  are 
more  uncertain,  and  an  engineer  always  hesitates  to  make  any 
statements  about  the  quality  of  earth  supposed  in  a  trench,  lest, 
for  example,  other  material  be  found  and  he  be  asked  for 
extra  compensation  because  of  his  misstatement.  A  sub- 
stantial change  in  the  quantities,  in  spite  of  this  clause,  might 
operate  to  extinguish  the  contract,  or  the  contractor  might 
recover  for  the  additional  work  at  the  unit  prices  named  in 
the  contract.  The  most  equitable  proceeding  is  certainly  for 
the  engineer  to  prepare  a  careful  and  complete  statement  of 
quantities  and  of  conditions  and  then  to  make  additional 
compensation  if  changes  are  made. 

E.  And  it  is  further  expressly  agreed  that  all  the  work,  labor  and 
materials  to  be  done  and  furnished  under  this  contract  shall  be  done 
and  furnished  strictly  pursuant  and  in  conformity  to  the  following 
specifications  and  to  the  direction  of  the  Engineer  as  given  from  time 
to  time  during  the  progress  of  the  work  under  the  terms  of  the  contract 
and  specifications,  which  said  specifications  form  part  of  this  agree- 
ment. 

The  plans  and  specifications  are  intended  to  be  explanatory  of  each 
other,  but  should  any  discrepancy  appear  or  any  misunderstanding 
arise  as  to  the  import  of  anything  contained  in  either,  the  parties  hereto 
further  agree  that  the  explanation  and  decision  of  the  Engineer  shall 
be  final  and  binding  on  the  Contractor,  and  all  directions  and  explana- 
tions required,  alluded  to,  or  necessary  to  complete  any  of  the  provi- 
sions of  this  contract  and  these  specifications  and  give  them  due  effect 
shall  be  given  by  the  Engineer.  Corrections  of  errors  or  omissions 
in  drawings  or  specifications  may  be  made  by  the  Engineer  when  such 
correction  is  necessary  for  the  proper  fulfillment  of  the  intention  of  such 
drawings  or  specifications,  the  effect  of  such  correction  to  date  from 
the  time  that  the  Engineer  gives  due  notice  thereof  to  the  Contractor. 

In  order  that  the  specifications  shall  be  equally  binding  with  the 
contract,  some  such  clause  as  the  above  is  necessary.  The  clauses 
of  the  specifications  are  often  general,  applicable  to  the  performance 
of  the  contract  rather  than  to  the  prosecution  of  the  construction, 
and  no  uncertainty  should  exist.  Often  the  specifications  and 
plans  are  not  attached  to  the  contract,  are  not  signed  nor 


CONTRACT  AND  SPECIFICATIONS  285 

described  nor  even  referred  to  in  the  contract.      In   such   cases 
they  have  no  bearing  on  the  interpretation  of  the  contract. 

There  is  a  tendency  to  give  more  weight  to  the  written  contract 
than  to  the  specifications  or  plans,  should  discrepancies  occur. 
Between  the  plans  and  specifications  there  is  no  room  for  choice. 
Both  are  prepared  presumably  by  the  same  engineer  and  with  the 
same  care.  Specifications  being  changed  more  easily,  it  is  reason- 
able to  expect  that  they  would  more  exactly  represent  tjie  true 
intentions  of  the  two  parties.  Written  matter  in  law  prevails  over 
printed  matter,  and  punctuation  is  interpreted  so  as  to  make  the 
instrument  rational  and  self-consistent.  Care  must  be  taken  not 
to  make  changes  in  the  plans  or  specifications  after  they  have  been 
signed,  without  the  consent  or  knowledge  of  both  parties,  since 
such  tampering  with  the  documents  may  be  legal  forgery.  Where 
plans  are  incomplete  or  insufficient,  the  contractor  in  general  is  not 
relieved  from  his  obligation  to  carry  out  the  evident  intention  of 
the  contract,  but  neither  is  the  contractor  liable  if  the  work  fails 
or  proves  worthless  after  having  been  faithfully  executed  according 
to  the  plans.  It  cannot  be  too  strongly  urged  that  complete 
detailed  plans  be  provided  far  enough  in  advance  of  the  execution 
of  the  contract  so  that  they  may  be  thoroughly  checked  and  all 
inconsistencies  with  the  specifications  eliminated. 

F.  It  is  further  agreed  that  the  said  Engineer  may  make  alterations 
in  the  line,  grade,  plan,  form,  position,  dimensions,  or  material  of  the 
work  herein  contemplated  or  of  any  part  thereof,  either  before  or  after 
the  commencement  of  construction  and  that  said  Board  may  at  any 
time  order  that  any  portion  of  the  sewer  shall  not  be  built.  If  such 
alterations  diminish  the  quantity  of  work  to  be  done  they  shall  not 
constitute  a  claim  for  damages  or  for  anticipated  profits  on  that  por- 
tion of  the  work  dispensed  with ;  if  they  increase  the  amount  of  work 
such  increase  shall  be  paid  for  according  to  the  quantity  actually  done, 
at  the  price  established  for  such  work  under  the  contract. 

Even  with  this  clause,  if  the  character  of  the  work  to  be  done 
is  so  changed  that  the  terms  of  the  contract  are  not  applicable, 
making  it  impossible  to  say  to  what  part  of  it  the  new  work  should 
be  applied,  the  contractor  would  be  entitled  to  recover  for  the 


286  SEWER   CONSTRUCTION 

value  of  all  the  work  as  if  there  had  been  no  contract.  A  verbal 
agreement  to  certain  changes  may  substitute  an  oral  agreement 
for  the  original  instrument,  and  the  authority  of  this  clause  does 
not  allow  the  engineer  to  arbitrarily  annul  the  contract.  The 
contractor,  to  an  extent,  loses  his  rights  to  claims  for  extra  com- 
pensation by  proceeding  to  execute  alterations  without  protest,  and 
his  right  to  recovery  often  depends  upon  his  having  given  notice  to 
the  company  that  he  considers  his  rights  invaded.  Where  extra 
work  is  the  result  of  the  engineer's  mistakes  in  lines  and  levels, 
and  the  contractor  is  required  to  follow  those  lines,  the  company 
which  employs  the  engineer  should  pay  for  it,  and  the  contractor  is 
not  limited  to  any  rate  fixed  by  the  contract.  Care  must  be  taken 
in  making  changes  that  they  are  not  of  such  a  character  as  to 
release  the  surety  bond  which  guarantees  the  performance  of  an 
express  contract  under  certain  definite  circumstances. 

SPECIFICATIONS. 

G.  (i)  The  Contractor  shall  make  all  requisite  excavation  for 
construction  of  foundation  walls,  screening  chambers,  pump  wells, 
sewer  and  drain  pipes  and  all  appertaining  structures;  do  all  pumping, 
bailing  and  draining;  all  sheeting  and  shoring;  all  fencing,  lighting  and 
watching;  furnish  and  drive  all  piles  required  and  as  directed;  put  in 
place  all  masonry  and  concrete;  construct  the  brick  sewer  as  shown 
on  the  drawings;  erect,  in  entire  conformity  to  the  plans  and  specifica- 
tions, the  brick  and  wooden  building  to  be  used  as  a  pumping  station ; 
furnish  and  put  in  place  the  cast  iron  force  mains;  furnish  and  put  in 
place  the  wrought  iron  air  pipes;  furnish  and  put  in  place  the  ejector 
chamber;  furnish  and  put  in  place  the  ejector  complete;  furnish  and 
put  in  place  the  flushing  and  overflow  pipes  from  the  pumping  station 
to  the  creek;  construct  the  chimney  complete,  as  specified;  refill  all 
trenches  and  excavation,  as  directed;  clear  away  all  rubbish  and 
surplus  material,  unless  claimed  by  the  Board,  and  bring  all  excavated 
material,  not  used  for  refilling,  to  a  smooth,  even  grade;  and  furnish 
all  materials,  tools,  implements  and  labor  required  for  the  complete 
construction  and  operation  of  Section. . .  .of  the  Sewerage  system  of 
the  City  of with  all  its  appurtenances. 

This  is  an  introductory  and  general  clause  of  the  specifications, 
rehearsing  the  general  obligation  of  the  contractor. 


CONTRACT  AND   SPECIFICATIONS  287 

(2)  All  necessary  lines,  levels  and  grades  will  be  given  by  the 
proper  marks,  and  the  Contractor  shall  provide,  at  his  own  expense, 
such  forms,  stakes,  plank  and  such  assistance  at  all  times  as  may  be 
required  by  the  Engineer  for  giving  the  same.     Material  ready  for 
immediate  use  in  setting  grades  shall  be  at  hand  when  required  by  the 
Engineer  or  his  assistants;  otherwise  they  may  pass  on  to  other  parts 
of  the  work  and  the  Contractor  shall  make  no  claim  for  damages  from 
consequent  delay.     If  the  Contractor,  through  wilfulness  or  careless- 
ness, removes  or  causes  the  removal  of  said  marks  before  the  prosecu- 
tion of  the  work  requires  it,  the  replacing  of  the  same  shall  be  at  the 
expense  of  the  Contractor. 

This  requirement  that  the  contractor  shall  provide  the  engineer 
with  stakes,  etc.,  is  customary.  The  second  sentence  of  the  clause 
is  for  the  purpose  of  expediting  the  work  of  a  level  party  with  many 
duties.  In  the  experience  of  the  author  it  has  been  very  useful. 
Thg  third  sentence  is  useful  rather  to  act  as  a  restraint  than  to  cause 
expense  to  the  contractor,  and  it  is  rarely  operative  as  it  reads. 

(3)  All  work  during  its  progress  shall  conform  truly  to  the  lines  and 
levels  given  by  the  Engineer  and  shall  be  built  in  accordance  with  the 
plans  and  directions  given  from  time  to  time  by  him,  subject  to  such 
modifications  and  additions  as  shall  be  deemed  necessary  by  him 
during  its  execution,  and  in  no  case  shall  work  in  excess  of  the  plans 
and  specifications  be  paid  for  unless  ordered  in  writing  by  him. 

This  clause  is  often  made  a  part  of  the  clause  just  preceding, 
except  for  the  last  phrase.  Section  H  of  the  contract  deals  with 
extra  work  more  specifically. 

(4)  The  Contractor  shall  not  (except  after  consent  from  the  proper 
parties)  enter  or  occupy  with  men,  tools,  or  materials,  any  land  except 
that  belonging  to  or  taken  by  the  city.     The  Contractor  shall,  when- 
ever so  required  by  the  Engineer,  erect  fences  along  the  roadways  and 
around  the  ground  occupied  by  him  and  of  such  a  character  as  will  be 
sufficient  for  the  protection  of  the  adjoining  property. 

This  clause  is  really  included  in  clause  Q,  since  a  violation 
involves  a  suit  for  trespass,  for  which  among  others  clause  H  is 
provided.  The  party  of  the  first  part  should  be  sure  that  rights 
of  way  are  secured  before  the  contractor  begins  work;  otherwise 
the  contractor  may  recover  for  the  inevitable  delay.  Without  this 


288  SEWER  CONSTRUCTION 

clause,  the  contractor  is  personally  liable  for  trespass  if  he  deposits 
earth  or  rubbish  on  an  adjoining  lot,  and  the  party  of  the  first 
part  is  liable  only  when  the  work  done  according  to  the  specifica- 
tions becomes  a  nuisance  or  a  permanent  injury  to  such  estates. 

(5)  Whenever  it  is  necessary  to  interfere  with  roads  or  railroads  the 
Contractor  shall,  at  his  own  expense,  provide  suitable  and  safe  bridges 
or  other  sufficient  accommodation  for  the  travel  on  said  roads  and 
shall  maintain  the  same  in  good  and  safe  condition  until  the  roads 
shall  be  restored,  when  he  shall  remove  all  bridges  and  other  temporary 
expedients  and  restore  said  road  to  conditions  suitable  for  use,  all  to  be 
satisfactory  to  the  Engineer. 

This  clause,  while  apparently  placing  the  burden  of  maintaining 
traffic  on  the  contractor  and  relieving  the  city  of  its  natural  obliga- 
tion to  keep  its  streets  in  a  safe  condition  for  travel,  has  been 
variously  interpreted  by  the  courts  on  the  ground  that  any  accident 
may  be  the  result  of  the  work  itself  and  not  of  its  unskillful  per- 
formance. The  courts  have  held  that  the  city  is  liable  if  injuries 
occur  on  account  of  neglect  of  proper  precautions.  This  does  not, 
however,  relieve  the  contractor  of  liability  if  he  or  his  servants  have 
been  negligent  or  careless  in  the  performance  of  his  contract. 

The  Contractor  shall  give  reasonable  notice  to  the  owners  of  rail- 
roads and  private  ways  before  interfering  with  them.  He  shall  provide 
watchmen,  red  lights,  and  fences,  at  his  own  expense,  and  take  such 
other  precautions  as  may  be  necessary  to  protect  life  and  property, 
and  shall  be  liable  for  all  damages  occasioned  in  any  way  by  his  act 
or  neglect  or  that  of  his  agents,  employees,  or  workmen. 

This  second  part  of  the  clause  is  probably  unnecessary.  The 
liability  for  accidents  or  damages  is  referred  to  in  clause  Q  of 
the  contract,  and  carelessness  or  negligence  would  make  him  liable 
in  the  eyes  of  the  law,  without  such  a  clause. 

EXCAVATION. 

(6)  Trenches  for  sewers  and  appurtenances  shall  be  excavated  in 
all  cases  in  such  manner  and  to  such  depths  and  widths  as  will  give 
proper  and  sufficient  room  for  building  the  structures  they  are  to  con- 
tain and  for  sheeting,  pumping,  draining,  or  placing  any  artificial 
foundation  for  the  structure. 


CONTRACT  AND   SPECIFICATIONS  289 

It  is  questionable  if  this  is  necessary.  The  contractor  ought  to 
be  allowed  to  open  and  dig  his  trenches  as  he  thinks  best,  provided 
the  structures  they  contain  are  not  interfered  with. 

Trenches  shall  be  opened  in  accordance  with  the  lines  and  grades 
given  for  the  work,  on  such  locations,  at  such  times,  and  only  so  far 
in  advance  of  the  work  as  may  be  required  by  the  Engineer.  But  no 
trench  shall  be  at  any  time  open  for  a  length  greater  than  three  hun- 
dred feet  from  the  point  where  the  back  filling  is  complete  to  the  solid 
ground  at  the  end  of  the  trench,  without  the  written  permission  of  the 
Engineer. 

Here  again  it  is  questionable  whether  the  engineer  ought  to  be 
allowed  to  dictate  to  the  contractor  how  the  work  shall  be  prose- 
cuted, in  what  order,  or  in  what  length  of  trench.  The  author, 
however,  had  great  trouble  with  one  contractor,  who  paid  sub- 
contractors for  trenching  and  pipe-laying  and  filled  in  the  trenches 
himself  at  his  convenience.  This  resulted  at  times  in  an  unneces- 
sary interference  with  travel  throughout  the  city,  and  this  clause 
has  been  used  with  good  effect  to  prevent  such  a  recurrence.  In 
streets  with  heavy  traffic  the  open  trench  distance  might  properly 
be  reduced  to  one  hundred  or  even  fifty  feet. 

All  excavations  shall  be  open  cut  from  the  surface  and  no  tunneling 
will  be  allowed  except  permission  be  previously  obtained  from  the 
Engineer. 

This  clause  is  intended  to  preserve  the  integrity  of  the  street. 
In  some  soils  it  saves  the  cost  of  sheeting  to  dig  an  open  trench 
about  eight  feet  long,  then  pass  by  four  feet  and  dig  again,  tunneling 
through  the  four  feet  of  solid  earth,  which  acts  as  a  brace  to  keep 
the  trench  from  caving.  The  objection  is  that  the  tunnel  is  not 
refilled  solidly  and  may  afterwards  settle.  If  it  does  not  settle, 
it  gives  a  different  surface  from  the  trench  part,  making  the  street 
uneven. 

(7)  All  surfacing  materials  from  excavations,  including  pavement, 
paving,  gravel,  road-metal,  soil,  turf,  etc.,  shall  be  carefully  removed 
and  kept  separate,  to  be  used  in  repairing  or  resurfacing  the  streets, 
road,  or  ground. 

This  clause  requires  the  contractor  to  throw  out  on  one  side  of 
the  trench  the  surface  material,  whether  that  be  loam  or  street 


290  SEWER   CONSTRUCTION 

surface,  so  that  it  may  be  used  separately  when  the  trench  is 
refilled.  It  usually  costs  the  contractor  nothing  but  a  little  fore- 
sight. 

(8)  The  materials  excavated  and  those  used  in  construction  shall 
be  so  placed  as  not  to  endanger  the  work,  and  so  that  free  access  may 
be  had  at  any  time  to  all  parts  of  the  trench  and  to  all  hydrants  and 
gates  in  the  vicinity.     They  shall  be  neatly  piled  and  trimmed  so  as 
to  inconvenience  as  little  as  possible  the  public  travel  or  the  adjoining 
residents.     All  streets,  roads,  railroads,  and  private  ways  shall  be  kept 
open  for  the  usual  travel,  and  the  materials  excavated  shall  be  so 
handled  and  placed  as  not  to  unnecessarily  interfere  therewith. 

This  clause  has  to  do  with  the  convenience  and  aesthetic  feelings 
of  the  public  rather  than  with  actual  dangers.  Sometimes  the 
contractor  is  obliged  by  this  clause  or  by  one  similar  to  place 
boards  or  canvas  on  a  lawn  before  excavation  is  begun.  Ready 
access  to  hydrants  and  water  gates  is  imperative,  although  without 
oversight  laborers  will  bury  a  hydrant  completely  if  placed  suit- 
ably. The  private  ways  are  usually  driveways  into  private  property 
which  may  be  blocked  by  a  pile  of  dirt. 

(9)  The  bottom  of  the  trench,  when  the  nature  of  the  earth  permits, 
shall  be  excavated  to  the  exact  form  and  size  of  the  pipe  to  be  laid 
therein.     Additional  excavation  shall  be  made  at  the  joints  of  pipe 
sewers  so  that  the  pipes  shall  have  a  continuous  and  even  bearing 
and  the  pressure  from  above  be  distributed  through  them  equally 
and  evenly. 

The  provisions  of  this  clause  ought  to  be  carried  out,  but  in  the 
case  of  pipe  sewers  it  is  rarely  done.  With  brick  and  concrete 
sewers,  it  is  for  the  interest  of  the  contractor  to  have  a  solid  bearing 
for  the  masonry,  and  the  excavation  is  made  as  desired.  But  it  is 
an  exception  even  with  this  clause  to  have  any  other  than  a  flat 
bottom  for  the  trench  and  satisfactory  bell  holes  are  equally  rare. 
Nevertheless  they  should  be  required. 

(10)  Should  excavation  below  grade  line  be  considered  necessary 
for  foundation  by  the  Engineer,  such  extra  excavation  shall  be  done  by 
the  Contractor,  for  which  he  shall  be  paid  as  provided  in  Article  O, 
item  — . 


CONTRACT  AND   SPECIFICATIONS  291 

Other  material  shall  be  deposited  in  place  of  that  removed,  as  pro- 
vided in  Article  G,  item — . 

It  is  manifestly  unfair  to  require  a  contractor  to  bind  himself  to 
excavate  an  unknown  amount  of  soft  material  from  the  bottom  of 
a  trench  at  the  bidding  of  the  engineer.  This  clause  provides  that 
he  shall  do  such  excavation  if  required,  that  he  shall  be  paid  for 
it  at  a  definite  prearranged  rate,  and  that  material  shall  be  sub- 
stituted for  that  removed,  also  at  a  definite  price. 

(n)  When  rock  is  encountered  it  shall  be  uncovered  and  after  it  has 
been  measured,  shall  be  taken  out  so  to  be  at  no  point  at  a  depth  less 
than  six  (6)  inches  below  the  grade  of  the  sewer. 

This  is  a  common  requirement.  It  is  supposed  to  give  a  better 
bearing  for  pipe  than  if  the  pipe  were  allowed  to  rest  at  one  point 
upon  rock  and  at  another  on  earth.  There  should  be  no  ambiguity 
possible,  however,  as  to  the  amount  of  rock  excavation  which  is 
to  be  paid  for  nor  as  to  the  cost  of  furnishing  and  placing  the 
dirt  necessary  for  the  six  inches  of  refill,  neither  of  which  is 
here  mentioned. 

(12)  All  excavation  will  be  measured  or  estimated  either  as  earth  or 
rock,  the  latter  to  include  all  boulders  of  one-half  (J)  cubic  yard  or 
more  in  volume.     All  other  materials  found  in  excavation,  however 
hard,  stiff  and  compact,  including  soft  and  disintegrated  rock,  which 
can  be  removed  with  a  pick,  will  be  estimated  and  paid  for  as  earth. 

In  some  cases  where  a  contract  for  excavation  of  earth  at  a  fixed 
rate  per  cubic  yard  has  been  made  and  where  it  has  been  shown 
by  contractors  and  engineers  that  the  material  excavated  was 
"hardpan,"  a  material  known  and  recognized  as  entirely  distinct 
from  common  earth,  and  that  it  is  customary  for  contractors  to 
receive  extra  compensation  for  excavating  it,  the  courts  have 
allowed  the  contractor  to  recover  what  it  is  reasonably  worth  to 
excavate  it. 

(13)  All  excavation  of  rock,  and  of  earth  over  rock,  will  be  esti- 
mated and  paid  for  as  three  (3)  feet  in  width  for  all  sizes  of  pipe. 
No  allowances  will  be  made  for  additional  width  at  manholes  or  else- 
where. 


292  SEWER   CONSTRUCTION 

This  width  should  vary  with  the  size  of  the  pipe  to  be  laid  and 
with  the  depth  of  the  trench.  In  shallow  trenches  for  6-inch  pipe 
2\  feet  width  may  be  more  equitable.  For  24-inch  pipe  in  a 
lo-foot  trench,  4  feet  would  be  nearer  the  width  actually  dug. 
It  is  self-adjusting,  however,  since  the  contractor  will  have  a  larger 
price  per  cubic  yard  if  he  thinks  the  width  given  is  not  as  wide  as 
he  will  excavate.  The  kind  of  rock  also  affects  the  width  to  be 
allowed,  the  sedimentary  rocks  allowing  a  narrower  trench  than 
the  igneous  rocks. 

(14)  The  prices  of  earth  excavation  shall  include  the  cost  of 
removal,  of  delay  from  or  damage  occasioned  by  any  timber  or 
masonry  structures,  logs,  trees  or  other  obstacles,  except  rock  as 
hereinbefore  specified. 

This  clause  makes  (12)  more  specific,  although  it  is  not  likely 
that  a  contractor  would  attempt  to  secure  extra  compensation 
because  of  buried  logs.  An  old  corduroy  road  a  few  feet  below 
the  surface,  however,  would  be  a  great  temptation  to  a  contractor 
for  a  claim  for  "extras"  except  for  this  clause. 

(15)  Blasts  shall  be  covered  with  mats  and  heavy  timber,  chained 
together,  and  other  necessary  precautions  shall  be  taken  for  the  protec- 
tion of  the  works,  buildings,  and  travel;  caps  or  other  exploders  shall 
in  no  case  be  kept  in  the  same  place  in  which  dynamite  or  other 
explosives  are  stored;  and,  in  general,  the  precautions  against  accident 
from  blasting  shall  be  entirely  satisfactory  to  the  Engineer.     No 
blasting  shall  be  done  within  thirty  (30)  feet  of  the  finished  sewer. 

The  courts  have  held  that  an  owner  cannot  perform  any  act 
on  his  own  premises  which  is  intrinsically  dangerous  and  where 
the  damage  would  be  a  necessary,  probable  or  natural  consequence. 
On  the  other  hand,  they  have  held  that  injury  occasioned  by 
negligent  blasting  of  rocks  by  a  contractor  did  not  make  the  city 
liable.  Probably  under  ordinary  conditions  the  contractor  would 
be  liable  for  damages  due  to  blasting  without  this  clause,  and  it  is 
wrong  in  principle  for  the  engineer  to  direct  the  work  of  the  con- 
tractor. The  last  sentence  is  due  to  the  one  instance  of  the  fracture 
of  a  lot  of  pipe  already  laid,  by  the  concussion  of  air  in  a  deep 


CONTRACT  AND   SPECIFICATIONS  293 

trench  due  to  a  heavy  blast.  A  good  many  blasts  are  fired,  how- 
ever, within  five  feet  of  a  finished  sewer,  the  end  being  covered, 
without  injury  to  the  sewer. 

(16)  The  Contractor  shall  be  liable  for  all  damages  to  persons  or 
property  caused  by  blast  or  explosives,  or  from  neglect  in  properly 
guarding  the  trenches,  and  no  compensation  to  said  Contractor  will, 
under  any  circumstances,  be  allowed  for  losses  thus  incurred. 

The  comment  on  the  preceding  clause  applies  also  here.  The 
clause  is  a  good  one  in  that  it  places  definitely  the  responsibility. 
The  author  remembers  a  case  of  a  gas  main  ignorantly  broken, 
just  before  work  stopped  for  the  night,  and  how  the  claim  of  the 
contractor  that  it  was  inevitable  on  account  of  the  location  and 
that  the  large  bill  of  the  gas  company  should  be  paid  by  the  city, 
was  effectually  resisted  by  reference  to  this  clause. 

(17)  The  Contractor  shall  at  his  own  expense  furnish,  put  in  place, 
and  maintain  such  sheeting,  bracing,  etc.,  as  may  be  required  to 
support  the  sides  of  all  excavation  (whether  above  or  below  the  sewer 
grade)  and  to  prevent  any  movement  which  could  in  any  way  diminish 
the  width  necessary  for  proper  drainage  or  otherwise  injure  or  delay 
the  work ;  all  slides  and  caves  shall  be  at  his  cost. 

Custom  and  usage  would  probably  require  a  contractor  who 
agreed  to  excavate  a  trench  at  a  certain  price  per  cubic  yard  to 
furnish  the  labor  and  material  for  sheeting  without  this  clause. 
However,  it  is  useful  as  making  the  sheeting  a  definite  part  of  the 
contractor's  work. 

(18)  If  it  is  necessary  to  interfere  in  any  manner  with  any  water 
or  gas  pipes,  drains,  catch-basins,  culverts,  or  other  similar  structures, 
public  or  private,  the  Contractor  shall,  at  his  own  expense,  sling,  shore 
up,  and  secure  and  maintain  a  continual  flow  in  said  structures,  and 
shall  repair  any  damages  done  to  any  of  said  structures  and  keep  them 
in  repair  until  the  final  acceptance  of  the  completed  work,  leaving 
them  in  as  good  condition  as  they  were  previous  to  this  interference, 
and  the  said  Contractor  shall  be  liable  for  all  damages  or  claims 
against  the  city  arising  from  neglect  or  carelessness,  or  in  any  way 
arising  from  any  interference  with  said  pipes.     While  it  is  supposed 
that  the  location  and  size  of  pipes,  drains,  etc.,  are  accurately  shown 


294  SEWER   CONSTRUCTION 

on  the  maps  in  the  Engineer's  office,  it  is  not  so  guaranteed,  and  no 
claim  shall  be  made  by  the  Contractor  on  account  of  any  pipe  being 
found  not  in  the  position  shown  on  the  map. 

The  larger  the  city  in  which  the  work  is  to  be  done  the  more 
important  does  this  clause  become.  In  connection  with  the  work 
on  the  New  York  subway,  for  example,  the  cost  of  keeping  water 
pipes,  gas  pipes,  sewers,  etc.,  all  properly  working  was  no  small 
item,  and  there  should  be  no  question  as  to  the  responsibility 
therefor. 

(19)  Care  shall  be  taken  not  to  move  without  the  consent  of  the 
proper  parties  any  water  or  gas  pipes,  culverts,  telegraph,  telephone, 
and  electric  poles  or  wires,  buildings  or  other   structures;   and  in 
crossing  these,  or  in  running  parallel  with,  or  near  them,  they  shall  be 
sustained  securely  in  place  until  the  work  is  complete  and  shall  then  be 
so  treated  as  to  render  their  condition  as  safe  and  permanent  as  before. 
If  so  directed  by  the  Engineer,  the  location  of  any  existing  work  shall 
be  changed  to  meet  the  requirements  of  the  sewer  and  appurtenances 
and  new  work  shall  be  added,  when  necessary,  to  leave  all  in  good 
working  order.     All  the  cost  of  such  changes  will  be  paid  for  as  extra 
work  solely  on  the  valuation  of  the  Engineer  and  depending  on  his 
decision  as  to  whether  the  work  is  or  is  not  incurred   under  this 
contract  in  the  work  required  of  the  Contractor. 

The  clause  discriminates  between  ordinary  care  of  structures 
referred  to  in  (18)  and  the  work  necessary  to  move  any  structure 
into  a  new  location  for  the  better  construction  or  maintenance  of 
the  new  work.  It  gives  opportunity  for  an  engineer  to  materially 
assist  the  contractor.  For  example,  if  a  water  pipe  line  is  curved, 
bringing  a  part  of  it  into  the  sewer  trench  where  it  must  be  sup- 
ported, the  engineer  might  direct  the  contractor  to  relay  the  water 
pipe  in  a  straight  line,  taking  it  away  from  the  sewer.  In  such  a 
case  the  cost  would  be  paid  for  as  extra  work.  Otherwise  the 
contractor  would  not  only  have  the  cost  of  slinging  the  pipe  in  his 
trench,  but  of  the  excavation  in  his  trench,  at  a  higher  rate  on 
account  of  the  obstruction  of  the  water  pipe. 

(20)  The  Contractor  shall  furnish  sufficient  pumping  plant,  and 
provide  and  maintain  drainage  in  the  trench  satisfactory  to  the  Kngi- 
neer.     In  wet  gravel  or  at  such  places  as  the  Engineer  may  direct, 


CONTRACT  AND   SPECIFICATIONS  295 

drain  tile,  to  be  furnished  by  the  city,  shall  be  laid  by  the  Contractor 
along  a  graded  bottom,  the  laying  to  be  paid  for  according  to  Article 

O,  item Water  shall  not  be  allowed  to  rise  on  any  masonry  until 

the  mortar  has  set  at  least  twenty-four  (24)  hours,  and  no  stream  of 
water  shall  flow  through  newly  laid  pipes  or  over  masonry  until  such 
time  as  the  Engineer  may  direct.  Sufficient  pumping  in  the  immedi- 
ate vicinity  of  the  new  pipe  joints  shall  be  at  all  times  maintained  so 
that  no  joint  shall  be  laid  in  water  or  have  water  on  or  around  it  until 
the  cement  shall  have  received  its  initial  set. 

The  more  the  risk  to  the  contractor  can  be  eliminated,  the 
nearer  the  proposals  and  the  contract  prices  will  be  to  the  actual 
cost.  The  contractor  should  not  be  required  to  furnish  an 
unknown  number  of  feet  of  drain  tile  without  special  compensation 
therefor.  It  is  unfortunate,  however,  that  the  clause  as  it  stands 
gives  opportunity  for  collusion  between  the  engineer  and  con- 
tractor. If  the  former  orders  drain  tile,  the  trench  drainage  costs 
the  contractor  nothing.  If  the  engineer  refuses  to  order  drain  tile, 
the  drainage  must  be  done  by  pumps  at  the  expense  of  the  con- 
tractor. It  is  to  be  hoped  that  in  a  clause  of  some  future  specifi- 
cations the  cost  of  pumping  will  be  allowed  the  contractor  at  so 
much  per  thousand  gallons,  so  that  there  may  be  no  inducement  to 
the  engineer  to  require  pumping  or  drain  tile  other  than  the  effect 
on  the  quality  of  the  work. 

(21)  All  water  from  the  sewer  trench,  and  from  any  sewers,  drains, 
water  courses,  etc.,  which  may  be  interfered  with,  shall  be  conveyed  to 
a  suitable  place  of  discharge  in  a  manner  satisfactory  to  the  Engineer. 

This  requirement  might  seem  unnecessary  except  that  a  con- 
tractor pumping  water  from  a  trench  is  not  usually  particular  as  to 
what  becomes  of  that  water.  The  clause  authorizes  the  engineer 
to  exercise  supervision. 

CEMENT. 

(22)  American  hydraulic  or  Portland  cement,  as  directed,  will  be 
furnished  to  the  Contractor  for  use  in  the  work. 

This  clause  assumes  that  the  city  will  furnish  the  cement.  If  the 
contractor  is  to  furnish  the  cement,  proper  specifications  may  be 
found  in  Baker's  "  Masonry  and  Foundations  "  or  in  Engineering 


296  SEWER   CONSTRUCTION 

Record  for  June  25,  1904,  page  791,  where  the  standard  specifica- 
tions proposed  by  the  American  Society  for  Testing  Materials  are 
given.  Excellent  specifications  for  the  care  and  control  of  cement 
on  work  are  given  in  Engineering  Record,  Vol.  50,  p.  243,  being 
those  used  on  a  concrete  arch  bridge  in  the  city  of  Hartford,  Conn. 

(23)  The  Contractor  shall  keep  all  cement  delivered  to  him  raised 
above  the  ground  several  inches  by  blocking  or  otherwise,  and  properly 
and  tightly  covered  from  exposure  to  the  weather  and  dampness. 
The  Contractor  will  be  held  responsible  for  any  loss  or  damage  to  the 
cement  after  its  delivery  to  him  at  the  railroad,  steamboat  or  store- 
house, as  the  Sewer  Board  may  select,  and  all  haulage  from  station, 
wharf  or  storehouse  shall  be  at  the  expense  of  the  Contractor. 

This  clause  is  essential  if  the  contractor  does  not  furnish  the 
cement,  since  otherwise  he  will  not  properly  care  for  it  after  it  has 

been  brought  on  the  work. 

« 

SAND. 

(24)  The  sand  for  use  in  the  mixture  of  cement  mortar  shall  be 
furnished  by  the  contractor.     It  shall  be  clean,  screened,  sharp  sand, 
free  from  loam,  vegetable  matter  or  other  foreign  substances,  and 
satisfactory  to  the  Engineer. 

There  is  a  growing  tendency  to  make  this  clause  more  definite 
by  naming  the  per  cent  of  foreign  matter  allowable  in  the  sand, 
thus  taking  from  the  engineer  the  absolute  power  given  by  the 
clause  as  it  stands.  Five  per  cent  of  clay  has  been  named  as  a 
suitable  maximum  amount. 

MORTAR. 

(25)  The  sand  and  cement  used  to  make  mortar  shall  be  thor- 
oughly mixed,  dry,  and  unless  otherwise  directed  by  the  Engineer, 
in  the  following  proportions:  for  sewer  pipe  joints,  one  part  by  meas- 
ure of  cement  to  one  part  of  sand;  for  covering  pipe  joints,  one  part  by 
measure  of  cement  to  three  parts  of  sand;  and  for  all  other  purposes 
one  part  by  measure  of  cement  and  two  parts  of  sand.     A  moderate 
amount  of  water  shall  afterwards  be  added  to  produce  a  paste  of 
proper  consistency,  and  the  whole  shall  be  thoroughly  worked  with 
hoes  or  other  tools.     A  fair  compensation,  as  determined  by  the 
Engineer,  will  be  made  to  the  Contractor  for  variations  of  the  above 


CONTRACT   AND   SPECIFICATIONS  297 

proportions.  The  Contractor  shall  at  his  own  expense  furnish  the 
water  for  mixing  mortar  and  for  all  other  purposes.  The  mortar  shall 
be  freshly  mixed  when  used,  that  is,  shall  be  made  only  in  sufficient 
quantity  for  the  work  in  hand  in  proper  boxes  made  for  the  purpose. 
No  mortar  shall  be  used  that  has  begun  to  set  or  become  hard.  All 
such  mortar  shall  be  thrown  away  and  not  used  in  any  capacity  on  the 
work. 

It  is  far  better  to  have  the  proportions  fixed  beforehand  than 
to  name  one  mixture  in  the  specifications  and  then  use  another 
on  the  work,  the  engineer  deciding  what  extra  compensation  the 
contractor  is  entitled  to  because  of  the  change.  See  also  comment 
on  (22). 

CONCRETE. 

(26)  Concrete  shall  be  used  in  the  foundations,  around  pipes,  and 
for  other  purposes  wherever  required  by  the  Engineer.     All  material 
necessary  to  make  the  concrete,  except  cement,  shall  be  furnished  by 
the  Contractor. 

Since  this  contract  assumed  a  unit  price  for  the  concrete  it  was 
important  to  specify  where  the  concrete  would  be  used,  since  its 
cost  would  vary  with  the  location.  In  some  kinds  of  work  there 
should  be  a  number  of  items  in  the  contract,  each  giving  the  price 
of  concrete  for  a  different  place. 

(27)  The  concrete  shall  consist  of  pebbles  or  broken  stones  of 
various  sizes;  and  shall  be  mixed  in  the  following  proportions:  five  (5) 
parts  by  measure  of  broken  stone  to  two  (2)  parts  of  sand  and  one  (i) 
part  of  cement.     The  broken  stone  shall  be  firm  and  sound  and  free 
from  clay  and  other  objectionable  material.     No  piece  shall  be  greater 
than  two  (2)  inches  or  less  than  one-quarter  (|)  inch  in  diameter. 
The  above  proportion  shall  be  varied,  if  so  desired  by  the  Engineer, 
and  a  fair  compensation  given  the  Contractor  for  said  change,  as 
determined  by  the  Engineer. 

This  again  allows  the  engineer  to  vary  the  proportions  and  to  be 
the  sole  judge  of  the  compensation,  if  any,  to  be  granted  the  con- 
tractor—  a  bad  principle.  This  is  not  a  complete  specification,  no 
distinction  being  made  between  gravel  and  broken  stone  and  no 
statement  being  made  as  to  whether  the  cement  is  to  be  measured 
in  the  original  package  or  loose. 


298  SEWER  CONSTRUCTION 

(28)  The  mixing  shall  be  done  in  proper  boxes,  in  a  manner  satis- 
factory to  the  Engineer,  and  after  the  materials  are  wet  the  work  must 
proceed  rapidly  until  the   concrete  is  in  place  and  so  thoroughly 
rammed  that  water  flushes  to  the  surface  and  all  the  interstices 
between  the  stones  are  entirely  filled  with  mortar.     Should  voids  be 
discovered,  when  the  forms  or  molds  are  removed,  the  defective 
work  shall  be  removed  and  the  space  refilled  with  suitable  material, 
satisfactory  to  the  Engineer.     It  shall  be  allowed  to  set  for  a  sufficient 
time,  to  be  determined  by  the  Engineer,  before  walking  over  or  work  ing 
upon  it  will  be  permitted.     Where  forms  are  required  to  hold  the 
concrete  in  place  they  shall  be  set  true  to  the  line  and  shall  be  securely 
fastened  so  that  they  will  not  get  out  of  place  while  the  concrete  is 
being  laid. 

This  clause  is  entirely  inadequate  for  any  large  work.  The 
method  of  mixing,  or  some  test  for  its  thoroughness,  should  be 
specified. 

(29)  The  quantity  of  concrete  to  be  paid  for  will  be  determined  by 
measurements  of  the  number  of  cubic  yards  of  concrete  deposited  in 
place,  in  conformity  with  the  plans  and  directionsof  the  Engineer.     An 
account  shall  be  kept  of  the  number  of  barrels  of  cement  used,  mixed 
as  above  specified,  and  the  Contractor  will  not  be  allowed  for  the  con- 
crete at  a  greater  rate  than  twenty-one  cubic  feet  of  concrete  per 
barrel  of  cement  used. 

This  clause  is  inconsistent  with  itself.  It  was  so  written  because 
it  was  expected  that  a  large  part  of  the  concrete  would  be  used  in 
and  around  sewer  pipes  where  exact  measurements  of  the  volume 
of  concrete  in  place  would  be  impossible,  but  it  was  not  satisfactory. 
It  would  be  better  to  have  the  amount  used  actually  measured  in 
a  box  if  place  measurement  is  not  feasible. 

BRICKWORK. 

(30)  All  brick  shall  be  of  good  quality,  hard  burned,  common  red 
brick.     The  brick  shall  be  thoroughly  wet  just  before  laying,  every 
brick  being  completely  bedded  in  mortar  on  its  bottom,  sides,  and 
top,  at  one  operation.     The  joints  shall  not  exceed  f  inch. 

The  outside  of  all  walls  or  sides  of  all  arches,  foundations,  or  man- 
hole walls,  or  where  directed  by  the  Engineer,  shall  be  plastered  with 
Portland  cement  mortar,  at  least  if  inch  thick.  All  internal  joints 


CONTRACT  AND  SPECIFICATIONS  299 

shall  be  raked  in  and  thoroughly  smoothed  with  mortar.  All  brick 
courses  shall  be  kept  level,  bonded,  and  laid  to  line,  either  plumb  or 
to  the  batter  required  by  the  drawing. 

This  clause  was  intended  for  manhole  brickwork  and  is  inade- 
quate for  the  brickwork  of  a  large  sewer.  The  quality  of  the  brick 
ought  to  be  more  specific.  The  thickness  of  joints  named  is  not 
possible  on  the  outside  of  a  manhole  wall,  much  less  of  a  small 
brick  sewer.  The  surfaces  to  be  plastered  ought  not  to  be  named 
by  the  engineer,  but  should  be  all  named  in  the  contract. 

IRON. 

(31)  The  cast  iron  used  for  manhole  covers  shall  be  tough  and 
have  a  tensile  strength  of  not  less  than  18,000  pounds  per  square  inch, 
with  a  light  gray  fracture.     The  castings  shall  be  free  from  cracks, 
blow-holes  or  other  imperfections,  straight,  true  to  pattern,  and  have  a 
workmanlike  finish.     The  castings  shall  be  thoroughly  cleaned  and 
coated  with  asphalt  varnish,  of  approved  composition,  and  shall  be  of 
the  weight,  shape  and  dimensions  shown  on  the  drawings. 

This  is  a  customary  clause  but  poor  in  many  respects.  No 
provision  is  made  for  test  pieces  and  therefore  it  is  not  likely  that 
the  tensile  strength  of  the  iron  will  ever  be  examined.  The 
strength  as  a  whole  might  well  be  tested  by  dropping  a  weight  of 
specified  amount  on  the  center  of  the  cover  as  it  rests  in  place  on 
the  frame.  The  possible  variation  in  weight  or  dimensions  from 
those  shown  on  the  drawings  should  be  stated  so  that  no  question 
of  the  proper  rejection  of  light-weight  castings  can  arise. 

SEWER  PIPE. 

(32)  The  main  sewer  shall  be  constructed  of  the  best  quality  of 
salt-glazed,  vitrified,  stoneware  sewer  pipe,  and  all  special  pieces  or 
specials  which  may  be  required  in  the  work  shall  be  of  the  same 
description  and  quality.     The  pipes  and  specials  must  be  submitted  to 
a  careful  inspection  and  must  conform  to  the  following  conditions, 
viz.: 

(33)  All  hubs  or  sockets  must  be  of  sufficient  diameter  to  receive 
for  their  full  depth  the  spigot  end  of  the  next  following  pipe  or  special 
without  any  chipping  whatever  of  either,  and  also  to  leave  a  space  of 


300  SEWER   CONSTRUCTION 

not  less  than  f  inch  in  width  all  around  for  the  cement  mortar  joint. 
Pipes  and  specials  which  cannot  be  thus  freely  fitted  into  each  other 
will  be  rejected. 

(34)  All  pipe  shall  be  in  sections  not  less  than  two  and  one-half 
(2$)  feet  in  length,  and  preference  will  be  given  to  sections  three  (3) 
feet  in  length.     The  sockets  for  six  (6)  and  eight  (8)  inch  pipe  shall  be 
at  least  two  and  one-half  inches  deep,  and  no  divergence  from  a  truly 
circular  cross  section  will  be  allowed. 

(35)  Any  pipe  or  special  which  exhibits  fire  cracks  of  a  size  calcu- 
lated, in  the  opinion  of  the  Engineer,  to  injure  the  pipe,  will  cause 
said  pipe  to  be  rejected. 

(36)  Any  pipe  or  special  which  is  found  to  be  cracked  through  its 
whole  thickness  from  any  other  cause  except  the  process  of  burning  in 
the  kiln  shall  be  rejected  at  once,  regardless  of  the  extent  of  such 
crack.     This  refers  particularly  to  damage  done  by  transportation,  by 
cooling,  or  by  frost. 

(37)  Irregular  lumps  or  unbroken  blisters  on  the  interior  surface 
of  a  pipe  or  special,  of  sufficient  size  and  number  to  form  an  appreci- 
able obstruction  to  the  free  flow  of  the  sewage,  will  be  cause  for  rejec- 
tion.     Small  broken  blisters  placed  at  the  top  of  the  pipe  will  not  be 
cause  for  rejection,  but  large  broken  blisters,  even  if  the  pipe  be  so  laid 
as  to  bring  such  blisters  on  the  top  of  the  sewer,  shall  be  cause  for 
rejection. 

(38)  Any  pipe  or  special  which  betrays  in  any  manner  a  want  of 
thorough  vitrification  or  fusion,  or  the  use  of  improper  materials  and 
methods  in  its  manufacture,  shall  be  rejected. 

(39)  All  pipe  and  specials  which  are  designed  to  be  straight  shall 
not  exhibit  any  material  deviation  from  a  straight  line  and  shall  not 
vary  more  than  three-eighths  (f )  inch  from  a  straight  line  in  a  length 
of  two  and  a  half  (2^)  feet.     Special  curves  and  bends  shall  substan- 
tially conform  to  the  degree  of  curvature  and  general  dimensions  that 
may  be  required. 

(40)  If  a  piece  be  broken  out  of  the  rim  forming  the  hub  or  socket 
of  a  pipe  or  special  without  injuring  the  body  of  such  pipe,  the  latter 
shall  be  rejected  if  the  length  of  said  broken  piece,  or  the  gap  left 
thereby,  is  greater  than  one-tenth  of  the  circumference  of  said  hub. 
In  case  a  defect  of  this  nature  and  within  the  limits  just  defined  occurs 
in  a  pipe  or  special,  the  latter  shall  also  be  rejected  unless  it  can  be  so 
fitted  in  the  sewer  as  to  bring  said  defect  on  the  upper  part  thereof. 


CONTRACT  AND   SPECIFICATIONS  301 

(41)  Pipe  to  be  used  in  the  work  shall  be  inspected  when  being  laid, 
and  the  Contractor  may  not  require  inspection  at  any  other  time  or 
place  nor  shall  an  inspection  at  any  other  time  relieve  the  Contractor 
from  his  responsibility  to  use  only  pipe  as  specified. 

In  Johnson's  "  Specifications "  may  be  found  details  of  the  per- 
missible size  of  fire  cracks  and  of  blisters,  the  original  specifications 
having  been  formulated  by  Emil  Kuichling  of  Rochester.  (35) 
and  (37)  would  by  his  specifications  be  perfectly  definite  and  not 
subject  to  the  opinion  of  an  individual.  If  the  clauses  above 
given  are  used,  the  Kuichling  detailed  definitions  might  well  be  given 
to  the  inspectors  to  guide  them  in  knowing,  for  example,  what  are 
"large  blisters."  (41)  is  inserted  because  the  contractor,  to  get 
his  rebate  on  pipe  broken  in  transit,  often  wishes  the  pipe  inspected 
as  they  are  taken  out  of  the  freight  car.  Then  he  demurs  if  pipe 
accepted  then  are  afterwards  rejected,  although  transportation  by 
wagon  from  car  to  trench  cracks  and  breaks  many  pipe. 

PIPE  LAYING. 

(42)  The  pipes  and  specials  shall  be  so  laid  in  the  trench  that  after 
the  sewer  is  completed  the  invert  shall  conform  accurately  to  the 
grades  and  alignments  fixed  and  given  by  the  Engineer. 

This  is  a  poor  clause.  The  pipe  is  continually  tested  as  it  is 
being  laid  by  the  inspector  or  engineer's  assistant,  and  the  contrac- 
tor might  very  well  say,  if  in  some  way  it  should  be  found  that  the 
pipe  after  being  laid  was  not  true  to  grade,  that  he  had  exercised 
no  control  and  therefore  could  not  be  held  responsible.  Again,  if 
settlement  occurs,  the  contractor,  under  the  specifications,  should 
not  be  held  responsible,  since  the  engineer,  not  he,  is  charged  with 
pronouncing  on  the  character  of  the  foundation.  This  question 
led  to  an  interesting  lawsuit  in  New  Orleans  (1907)  in  which  the 
opinion  of  the  contractor  was  upheld  by  the  courts. 

(43)  All  pipes  and  specials  shall  be  laid  to  the  grade  given  by  the 
Engineer  and  in  such  manner  as  he  directs,  with  joints  close  and  even, 
butting  all  around,  special  care  being  taken  that  there  is  no  sagging  of 
the  spigot  end  in  the  hub,  and  that  a  true,  even  surface  is  given  to  the 
invert  throughout  the  entire  length  of  the  sewer.     A  narrow  gasket 
of  jute  shall  be  provided  by  the  Contractor,  to  be  well  soaked  in  neat 


302  SEWER  CONSTRUCTION 

cement  grout  and  introduced  between  the  hub  and  spigot,  and  well 
and  properly  rammed.  It  shall  in  all  cases  be  driven  to  the  bottom  of 
the  hub  to  leave  room  for  the  mortar  as  specified.  The  space  between 
the  spigot  and  hub  shall  then  be  entirely  filled  with  mortar  thoroughly 
pressed  in  on  the  bottom,  sides,  and  top,  and  every  precaution  taken 
to  secure  a  water-tight  joint.  The  mortar  shall  be  applied  with  a 
rubber  mitten  and  rammed  or  compacted  with  a  wooden  calking  tool. 
The  joint  shall  be  finished  with  a  neat  and  generous  bevel  made  with 
the  mitten.  After  the  joint  is  thus  made,  a  covering  of  cement  mortar 
(one  to  three)  shall  be  placed  around  and  under  the  joint,  said  covering 
to  be  at  least  two  inches  in  thickness  from  the  bell  entirely  around  the 
pipe.  The  interior  of  each  joint  shall  be  scraped  clean  of  all  pro- 
jecting mortar,  and,  when  the  size  of  pipe  permits,  pointed.  No 
length  of  pipe  shall  be  laid  until  the  previous  length  laid  has  had  suffi- 
cient fine  earth  filled  and  tamped  around  it  to  securely  hold  it  in  place 
so  as  to  prevent  any  movement  or  disturbance.  If,  in  making  any 
joints,  previous  lengths  are  moved  or  disturbed  so  as  to  break  joints 
made  and  covered,  the  pipe  and  joints  shall  be  uncovered  and  the 
joints  remade. 

For  pipe  sewers,  this  is  the  most  important  clause  in  the  specifi- 
cations. The  value  of  the  sewer  system  depends  on  the  tightness 
of  the  joints.  Yet  contractors  usually  assume  that  so  long  as 
the  pipe  are  placed  in  the  trench  and  a  little  cement  wiped  over 
the  top  of  the  joint,  the  engineer  ought  to  be  satisfied.  If  only  the 
mortar  were  made  barely  plastic  and  then  rammed  into  the  joint 
with  a  wooden  stick  until  the  joint  space  was  filled,  a  tight  joint 
might  be  expected.  Similarly,  the  provision  that  pipes  newly 
laid  shall  not  be  disturbed  is  rarely  observed,  although  freedom 
from  disturbance  is  essential  if  the  joints,  once  made,  shall  set 
without  cracks  or  breaks. 

(44)  When  necessary,  in  order  to  facilitate  the  work  and  prevent 
disturbance  of  pipe  already  laid,  pipes  and  specials  shall  first  be 
properly  fitted  together  in  the  order  in  which  they  are  to  be  used,  and 
marked  before  being  lowered  into  the  trench. 

This  is  seldom  done,  although  if  two  pipes  were  fitted  together 
on  the  bank  and  cemented  together,  and  after  the  joints  had  set, 
lowered  into  the  trench  as  pieces  six  feet  long,  the  number  of  poor 
joints  would  be  much  reduced. 


CONTRACT  AND   SPECIFICATIONS  303 

(45)  The  drainage  of  the  trench  shall  be  so  effected  as  not  to  allow 
a  stream  of  water  to  run  through  the  newly  laid  pipe,  washing  the 
mortar  out  of  the  joints. 

This  clause  prohibits  what  is  a  very  common  practice  with  con- 
tractors. The  clause  should  be  strictly  enforced. 

(46)  The  price  for  laying  sewer  pipe  shall  include  the  placing  and 
laying  and  properly  plugging  with  stoppers  of  all  branches  or  other 
specials  in  the  manner  and  at  the  points  required  by  the  Engineer. 

In  wet  ground  a  large  amount  of  leakage  comes  from  poorly 
plugged  Y's.  Special  care  should  be  taken  to  see  that  every  Y 
and  T  is  plugged  and  that  not  any  are  overlooked. 

(47)  Before  leaving  the  work  at  any  time  the  sewer  shall  be  securely 
closed  at  its  open  end,  and  after  the  work  is  completed  the  pipe  shall 
be  carefully  and  thoroughly  cleaned  of  all  refuse,  earth,  stones  and 
rubbish. 

To  this  clause  might  properly  be  added  the  requirement  that  a 
cleaner  of  some  definite  description  be  kept  in  the  pipe  and  dragged 
ahead  as  the  work  progresses. 

(48)  The  length  of  pipe  to  be  paid  for  will  be  determined  by 
measurements  of  the  number  of  lineal  feet  actually  laid,  except  that  no 
deduction  will  be  made  for  pipe  left  out  at  manholes. 

This  is  incomplete  in  two  respects.  It  does  not  say  whether  the 
measurements  are  to  be  made  horizontal  or  on  the  grade  of  the 
sewer,  the  latter  being  proper,  nor  does  it  say  whether  the  lengths 
of  Y's  and  T's  are  to  be  included.  In  section  O  the  price  for  Y's 
is  stated  to  be  "in  addition  to  the  cost  of  straight  pipe,"  but  a 
statement  to  that  effect  should  properly  be  included  here. 

(49)  The  right  is  reserved  to  connect  any  lateral  sewer  or  sewers 
with  the  sewers  herein  specified  or  to  grant  permits  to  any  person  or 
persons  to  make  house  connections  therewith  at  any  time  before  the 
final  completion  of  the  work,  and  said  Contractor  shall  not  interfere 
with  or  place  obstruction  in  the  way  of  such  persons  as  may  be 
employed   in  building   such   sewer  or   sewers  or   in  making  such 
connections. 

Such  a  practice  as  is  suggested  by  this  clause  is  a  mistake  because 
it  gives  the  contractor  ground  for  claiming  that  his  work  has  been 


304  SEWER   CONSTRUCTION 

accepted  when  connections  are  made  to  it,  and  because  it  may 
allow  the  contractor  to  claim  damages  or  avoid  his  own  obligations, 
in  the  case,  for  example,  of  a  connection  bringing  a  deposit  of  mud 
into  a  sewer  line  which  has  itself  not  been  properly  cleaned  out. 

(50)  Manholes    of  hard  brick  laid  in  cement   mortar  shall  be 
constructed  at  such  points  as  may  be  designated,  by  and  according  to 
directions  and  plans  given.     The  brick  shall  have  a  crushing  strength 
of  at  least  5,000  pounds  per  square  inch  and  shall  be  laid  with  lines  and 
templates  to  agree  with  the  drawings  provided  by  the  Engineer.     The 
manholes  will  generally  be  four  (4)  feet  in  diameter  at  the  bottom  in 
the  clear  and  diminish  to  two  (2)  feet  in  diameter  at  the  top  of  the 
masonry,  which  shall  be  eight  (8)  inches  below  the  grade  of  the  street, 
and  they  shall  be  fitted  with  a  cast-iron  head  and  cover,  and  such  other 
metal  work  shall  be  used  as  may  be  directed.     The  Contractor  shall 
furnish    the    iron    and  metal    work    as    provided   in    Section    31 
according  to  the  drawings  of  the  Engineer,  the  manhole  covers  to  be 
paid  for  according  to  section  O,  item  — . 

Some  of  this  is  included  in  section  30,  and  except  that  it  is  desir- 
able to  have  a  section  specifying  the  use  of  manholes,  this  whole 
clause  might  be  omitted.  The  first  and  last  sentences  are  the 
important  ones. 

(51)  The  Contractor  shall  build  into  each  manhole,  at  points  as 
directed,  one  or  two  lengths  of  eight  (8)  inch  pipe  for  future  connec- 
tions with  the  lateral  sewers,  to  be  closed  with  a  stoneware  cap  set  in 
cement.     The  cost  of  such  pipes  and  caps  and  all  the  labor  connected 
therewith  shall  be  included  in  the  cost  of  the  manhole  and  no  addi- 
tional compensation  will  be  allowed  therefor. 

This  clause  applies  to  trunk  sewers  where  the  connecting  laterals 
are  not  to  be  built  at  the  same  time.  The  matter  of  steps  should 
be  included  in  this  clause  or  in  the  one  preceding. 

(52)  The  floor  and  invert  shall  be  built  of  concrete  or  brick,  as 
directed  by  the  Engineer,  the  invert  having  a  cross  section  of  the  exact 
shape  of  the  inverts  of  the  sewers  which  it  connects;  changes  in  size 
shall  be  made  evenly  and  gradually,  and  shall  in  all  ways  conform  to 
the  drawings  furnished. 

It  might  be  desirable  to  specify  whether  the  contractor  would 
be  allowed  to  form  the  inverts  by  hand  or  whether  the  engineer 


CONTRACT  AND   SPECIFICATIONS  305 

would  require  the  use  of  forms.     The  use  of  split  pipe  might  also 
be  included. 

(53)  The  brickwork  in  the  walls  shall  be  eight  (8)  inches  thick 
throughout,  unless  otherwise  ordered  by  the  Engineer,  and  shall  be 
smoothly  plastered   on   the   outside  with  a   three-eighths   (f)   inch 
coating  of  Portland  Cement  mortar. 

If  manhole  walls  thicker  than  8  inches  are  to  be  used  with  deep 
manholes,  it  ought  to  be  specified  and  not  left  to  the  engineer, 
who  by  this  clause  might  require  the  contractor  to  build  them  all 
with  12-inch  walls,  although  the  contractor's  price  was  based  on 
8-inch  walls. 

(54)  Each  manhole,  on  its  completion,  shall  be  thoroughly  cleansed 
of  all  refuse  or  rubbish  and  shall  be  so  kept  until  the  final  acceptance 
of  the  completed  work. 

This  is  to  prevent  the  dirt  being  gradually  washed  into  the  sewer 
pipe  where  it  may  lie  undiscovered. 

BACK  FILLING. 

(55)  The  trench  and  other  excavations  shall  be  refilled  with  such 
excavated  material,  and  in  such  order,  as  may  be  from  time  to  time 
directed  by  the  Engineer.     In  covering  the  sewers  and  filling  around 
manholes,  the  earth  shall  be  brought  up  evenly  on  both  sides  of  the 
sewers  and  around  manholes  so  that  no  unbalanced  pressure  is  brought 
to  bear  upon  the  masonry  or  pipe.     The  filling  about  all  pipes,  and 
for  a  depth  of  two  (2)  feet  over  them,  shall  be  made  of  earth,  free  from 
stones,  thoroughly  and  carefully  rammed,  in  layers  not  exceeding  four 
(4)  inches,  and  special  care  shall  be  taken  in  filling,  about  and  under 
as  well  as  over  all  pipe,  that  the  earth  is  thoroughly  compacted  to  the 
full  width  of  the  trench,  and  no  voids  or  pockets  of  soft,  compressible 
material  left  under  or  about  the  sewer.     Back  filling  shall  be  spread 
in  layers  not  exceeding  one  (i)  foot  in  thickness,  unless  otherwise 
specified,  and  shall  be  well  watered  and  rammed.     Or,  when  an 
abundance  of  water  can  be  obtained  and  the  Engineer  so  directs,  the 
filling  shall  be  thrown  into  the  trench  and  allowed  to   settle  into 
place  through  a  suitable  depth  of  water.     A  careful  and  thorough 
settling  of  the  earth  back  into  the  trench,  by  ramming  or  otherwise, 
will  be  insisted  upon,  and  the  amount  of  surplus  dirt  over  the  refilled 
trench  shall  not  be  such  at  any  time  as  to  offer  any  obstruction  to 


306  SEWER   CONSTRUCTION 

driving  or  to  such  a  complete  use  of  the  street  as  was  had  before  the 
excavation.  No  stones  larger  than  one  foot  in  diameter  shall  be  used 
in  back  filling,  and  all  stones  used  in  filling  must  be  separately  sur- 
rounded with  earth  filling.  No  frozen  earth  shall  be  used  for  filling. 

This  clause  is  not  entirely  satisfactory  but  neither  is  any  other 
on  this  subject.  Some  engineers  specify  the  number  of  rammers 
to  be  employed;  others  require  all  the  dirt  excavated  or  a  certain 
part  of  it  to  be  replaced ;  and  others  require  the  contractor  to  keep 
the  surface  in  good  order  for  a  long  period.  It  is  impossible  in  a 
rock  trench  to  have  the  stones  used  in  filling  separately  surrounded 
with  earth,  though  it  is  a  proper  requirement  for  boulders  found 
in  clay  loam.  The  last  sentence  also  has  to  be  often  violated, 
although,  when  the  lumps  thaw  out,  the  trench  generally  settles. 

(56)  That  portion  of  the  sheeting  extending  below  the  top  of  the 
pipe  must  be  withdrawn,  unless  otherwise  ordered  by  the  Engineer, 
and  before  the  back  filling  has  been  carried  more  than  one  foot  above 
the  top  of  the  pipe.     As  the  trench  is  being  refilled,  the  sheeting,  etc. 
shall  be  so  removed  as  to  avoid  the  caving  in  of  the  trench.     The 
vacancies  left  by  the  sheeting  shall  be  carefully  refilled  by  ramming 
with  tools  especially  adapted  for  the  purpose,  and  by  watering  or 
otherwise  as  may  be  directed. 

This  clause  is  intended  to  prevent  holes  being  left  on  one  side 
of  the  pipe  so  that  by  unbalanced  pressure  the  pipe  might  be 
crowded  out  of  line.  If  the  sheeting  is  not  withdrawn  before  the 
filling  has  progressed  very  far,  the  holes  left  will  not  be  well  filled. 
In  a  recent  case  which  came  to  the  attention  of  the  author,  the 
contractor  was  allowed  to  leave  about  $4000  worth  of  sheeting  in 
a  trench,  where  this  clause  might  have  been  enforced  and  that 
amount  saved. 

(57)  When  the  Engineer  decides  that  the  sheeting  or  bracing  cannot 
be  removed  without  injury  to  the  work,  it  shall  be  left  in  place  and 
the  Contractor  will  be  paid  for  the  same  as  provided  in  Article  O,  item 
13.     But  no  sheeting  will  be  paid  for  unless  a  bill  for  the  same  accom- 
panied by  the  written  order  of  the  Engineer  be  presented  within  one 
month  from  the  time  that  the  sheeting  is  placed  in  the  trench. 

The  question  of  extra  work,  to  which  this  clause  pertains,  is 
taken  up  under  Section  H.  A  contractor  will  leave  sheeting  in 


CONTRACT  AND   SPECIFICATIONS  307 

place  rather  than  draw  it  if  he  has  hopes  that  the  engineer  may 
approve  his  bill  for  it.  The  engineer  on  construction  ought  to 
make  it  very  clear  whether  he  means  to  indorse  such  a  claim,  since 
silence  is  often  taken  by  the  courts  to  mean  assent. 

(58)  In  case  sufficient  suitable  material  for  the  refilling  is  not 
furnished  by  the  excavation  of  the  trenches,  that  which  is  suitable  will 
be  provided  by  the  city  and  shall  be  hauled  and  placed  by  the  Con- 
tractor.    If  the  haulage  of  such  material  exceeds  a  distance  of  five 
hundred  feet  an  allowance  of  three-quarters  of  a  cent  per  cubic  yard 
will  be  made  for-each  one  hundred  feet  of  haul  over  and  above  five 
hundred  feet. 

This  clause  is  a  logical  necessity  if  the  provisions  of  (55)  and  (n) 
requiring  the  pipe  to  be  bedded  in  earth  even  in  rock  trenches  where 
excavation  has  been  carried  six  inches  below  the  pipe  are  to  be 
carried  out.  Practically  it  is  seldom  enforced.  If  frozen  clay 
should  be  objected  to  for  back  filling,  this  clause  might  be  used  to 
have  the  filling  made  with  sand  or  gravel. 

(59)  All  surplus  earth  or  other  material  shall  be  removed  by  the 
Contractor  unless  claimed  by  the  city.     If  such  extra  material  be 
claimed  by  the  city,  it  shall  be  hauled  and  deposited  at  such  points  as 
the  Engineer  may  direct,  within  a  distance  of  five  hundred  (500)  feet, 
without  extra  compensation  to  the  Contractor.     If  the  length  of  such 
haulage  exceeds  five  hundred   (500)   feet,  an  allowance  of  three- 
quarters  (f )  of  a  cent  per  cubic  yard  will  be  made  for  each  one  hundred 
feet  of  haul  over  and  above  the  five  hundred  (500)  feet.     If  excavated 
rock  or  sand  be  removed  by  the  city,  making  a  deficiency  of  back 
filling  at  those  particular  points,  such  deficiency  of  back  filling  will  be 
made  good  by  the  city. 

As  a  matter  of  law,  any  extra  material  excavated  by  the  contractor 
is  the  property  of  the  abutters  if  their  title  extends  to  the  center  of 
the  street,  and  this  clause  would  hold  only  by  the  waiver  of  the 
abutter's  rights.  If  the  contractor,  for  example,  should  dig  up  a 
lot  of  sand  or  gravel  to  use  on  other  parts  of  the  work,  the  abutters 
could  appropriate  it,  pile  it  up  on  their  lots,  and  defy  both  the 
city  and  the  contractor  to  touch  it. 


308  SEWER  CONSTRUCTION 

(60)  The  surface  of  the  ground  in  streets  and  elsewhere  shall  in  all 
cases  be  left  in  as  good  condition  as  it  was  before  the  commencement 
of  the  work,  and  except  by  written  permission  of  the  Engineer,  the 
street  surface  in  a  given  block  shall  not  be  disturbed  for  a  longer  time 
than  six  days,  and  no  new  trench  in  any  part  of  the  work  called  for  in 
this  contract  shall  be  opened  without  special  direction  from  the 
Engineer,  should    the  surface  of    the  street  within  said   block  be 
disturbed  for  more  than  the  specified  period  of  six  days.     When  the 
surface  is  of  gravel  or  broken  stone,  it  shall  be  well  rolled  with  a  heavy 
roller;  the  whole  work  of  refilling  and  resurfacing,  of  relaying  brick 
or  other  pavement  with  their  foundations,  shall  be  done  in  a  manner 
to  prevent,  as  far  as  possible,  after-settlement.     The  Contractor  shall 
keep  the  street  service  over  and  along  the  trench  and  other  excavations 
in  a  safe  and  satisfactory  condition,  and  shall  be  responsible  for  any 
accident  that  may  occur  on  account  of  any  defective  condition  of  said 
surface.     All  fences  and  other  structures  in  the  vicinity  shall  be 
repaired  or  replaced.     All  trees  in  the  vicinity  shall  be  protected. 

This  requirement  that  work  shall  be  completed  within  six  days 
in  one  block  cannot  be  strictly  adhered  to  and  therefore  perhaps 
should  not  be  included.  But  it  is  of  great  service  in  the  case  of  a 
contractor  who  finds  one  part  of  the  work  difficult  and  therefore 
wishes  to  let  it  drag  while  he  pushes  other  and  more  profitable 
parts  of  the  work  to  completion. 

(61)  Whenever  the  sewer  is  laid  under  a  brick  pavement  which  is 
required  to  be  taken  up  and  relaid,  an  allowance  to  the  Contractor  of 
eight  (8)  cents  will  be  made  for  each  linear  foot  of  pavement  relaid. 

It  was  expected  that  eight  cents  would  be  a  fair  compensation  for 
relaying  the  pavement,  but  it  was  too  low.  Probably  twelve  cents 
would  be  a  better  estimate  of  its  cost. 

(62)  As  the  work  progresses,  all  rubbish  and  refuse  and  all  unused 
material  and  tools  shall  be  removed  at  once  from  the  ground.     When- 
ever this  cleaning  of  rubbish  from  the  street,  or  the  repairing  of  the 
street  surfaces,  fences,  or  other  damages  is  neglected,  the  Engineer  will 
give  notice  to  that  effect  to  the  Contractor,  and  if  such  rubbish  is  not 
removed,  or  if  said  repairs  are  not  done  within  two  days  thereafter,  or 
if  the  said  Contractor  does  not  at  once  take  the  necessary  precautions 
to  ensure  the  safety  of  travel,  the  Engineer  may  employ  other  parties 
to  do  such  work  and  the  expense  thus  incurred  will  be  deducted  from 
any  money  due  or  that  may  become  due  the  Contractor. 


CONTRACT  AND   SPECIFICATIONS  309 

The  process  of  cleaning  up  is  one  which  seems  generally  obnox- 
ious to  a  contractor.  The  clause  gives  to  the  engineer  power  to 
remedy  dangerous  conditions,  but  he  should  be  slow  to  do  anything 
not  immediately  needed.  Otherwise  the  contractor  may  claim 
excessive  cost  or  undue  refinement  in  the  work,  and  it  is  a  tempta- 
tion sometimes  for  the  engineer  to  make  the  street  surface  even 
better  than  at  the  beginning  at  the  expense  of  the  contractor. 

(63)  When  for  any  reason  the  work  is  left  unfinished,  all  trenches 
and  excavations  shall  be  filled  and  the  roadway  and  sidewalks  be 
left  unobstructed  and  with  the  surface  in  a  safe  and  satisfactory 
condition. 

If  this  happens  on  account  of  a  change  of  plans  or  is  the  fault 
of  the  city  or  its  engineer,  the  city  should  pay  for  it.  Nothing  is 
said  in  the  clause  about  who  is  to  pay  for  the  refilling. 

GENERAL. 

(64)  The  Contractor  shall  use  such  appliances  for  the  performance 
of   all  the  operations  connected  with   the  work  embraced   in  this 
contract  as  will  secure  a  satisfactory  quality  of  work  and  maintain  a 
rate  of  progress  which,  in  the  opinion  of  the  Engineer,  will  secure  the 
completion  of  the  work  within  the  time  herein  specified.     If  at  any 
time  before  the  commencement  or  during  the  progress  of  the  work 
such  appliances  appear  to  the  Engineer  to  be  inefficient  or  inappro- 
priate for  securing  the  quality  of  work  required,  or  the  said  rate  of 
progress,  he  may  order  the  Contractor  to  increase  their  efficiency  or  to 
improve  their  character  and  the  Contractor  must  conform  to  such 
order.     But  the  failure  of  the  Engineer  to  demand  such  increase  of 
efficiency  or  improvement  shall  not  relieve  the  Contractor  from  his 
obligation  to  secure  the  quality  of  work  and  the  rate  of  progress 
established  in  these  specifications. 

This  clause  is  a  warning  clause  of  which  section  P  is  the  logical 
sequence  if  no  improvement  is  secured.  It  is  a  useful  club,  although 
of  itself  it  probably  would  have  but  little  weight. 

(65)  Whenever  the  Contractor  is  not  present  on  any  part  of  the 
work  where  it  may  be  necessary  to  give  directions,  orders  will  be  given  •   . 
by  the  Engineer  to,  and  will  be  received  by,  the  superintendent, 
overseer,  or  foreman  of  the  Contractor  who  may  have  charge  of  the 
particular  work  in  relation  to  which  the  orders  are  given. 


310  SEWER  CONSTRUCTION 

In  spite  of  this  clause,  directions  should  always  be  given  to  the 
contractor  rather  than  to  his  employees.  Responsibility  for  the 
work  hinges  upon  its  control,  and  if  the  contractor  is  to  be  held 
responsible  he  must  not  be  unwisely  interfered  with,  nor  orders 
given  to  his  employees  differing  from  those  he  has  already  given 
except  by  virtue  of  pressing  necessity. 

(66)  Any  unfaithful  or  imperfect  work  that  may  be  discovered 
before  the  final  acceptance  of  the  work  shall  be  corrected  immediately 
on  the  requirement  of  the  Engineer,  notwithstanding  that  it  may  have 
been  overlooked  or  approved  by  the  proper  inspector. 

(67)  The  inspection  of  the  work  shall  not  relieve  the  Contractor  of 
any  of  his  obligations  to  perform  sound  and  reliable  work  as  herein 
described.     And  all  the  work,  of  whatever  kind,  which  during  its 
progress  and  before  it  is  finally  accepted  may  become  damaged  for  any 
cause,  shall  be  properly  taken  up  or  removed,  so  much  of  it  as  may 
be  objectionable,  and  be  replaced  by  good  and  sound  work  satisfac- 
tory to  the  Engineer. 

The  courts  have  held  that  if  the  inspectors  are  clothed  with  the 
authority  usually  bestowed  upon  engineers  in  construction  contracts 
and  the  work  has  been  accepted  and  no  fraud  has  been  practiced 
by  the  contractor,  the  city  cannot  recover  for  defective  work  or 
materials  afterwards  discovered.  But  the  failure  of  an  inspector 
to  note  defects,  or  the  monthly  certificates  of  the  engineer,  do  not 
constitute  a  waiver  of  defects  in  quality. 

(68)  And  it  is  further  agreed  that  if  the  work,  or  any  part  thereof, 
or  any  material  found  or  brought  on  the  ground  for  use  in  the  work, 
shall  be  condemned  by  the  Engineer  as  unsuitable  or  not  in  conformity 
with  the  specifications,  the  Contractor  shall  forthwith  remove  such 
materials  from  the  work,  and  rebuild  or  otherwise  remedy  such  work 
as  may  be  directed  by  the  Engineer. 

In  order  to  make  this  clause  effective,  there  must  be  definite 
specifications  as  to  the  quality  required.  If  the  materials  or  work- 
manship meet  the  spirit  of  the  specifications,  the  engineer  cannot 
order  changes  when  he  finds  that  the  results  are  not  as  good  as  he 
wished. 


CONTRACT  AND   SPECIFICATIONS  311 

(69)  The  Contractor  shall  neither  bring  nor  allow  others  to  bring 
any  spirituous  or  fermented  liquor  or  other  intoxicants  upon  the 
ground  occupied  for  the  prosecution  of  the  work.     Neither  shall  he 
furnish  or  allow  others  to  furnish  liquor  or  other  intoxicants  to  the 
workmen  in  his  employ  or  to  any  person  or  persons  in  the  vicinity. 

This  clause  is  probably  not  usually  justifiable.  The  police 
power  of  a  city  can  deal  with  drunkenness,  and  the  engineer  needs 
this  clause  only  when  the  employment  of  a  drunkard  endangers 
the  quality  of  the  work. 

(70)  Any  workman,  in  the  employ  of  the  Contractor,  who  shall  be, 
in  the  opinion  of  the  Engineer,  either  detrimental  to  the  good  of  the 
work  by  willful  disobedience  or  careless  disregard  of  orders,  or  who 
shall  be  persistently  offensive  to  the  community  where  work  is  being 
carried  on,  in  his  language  or  habits,  shall    be  dismissed   by  the 
Contractor  and  not  again  be  employed. 

"  If  the  party  of  the  first  part  retains  the  power  to  select  and 
discharge  the  workmen  and  can  control  them  in  the  discharge  of 
their  duties,  it  may  justly  be  regarded  as  responsible  for  their 
misconduct  and  negligence"  and  this  in  spite  of  clauses  to  the 
contrary.  The  results  of  the  work  may  properly  be  specified,  and 
the  engineer  may  give  directions  from  time  to  time  if  necessary  to 
secure  such  results,  but  the  engineer  should  not  retain  present 
control  of  the  mode,  manner,  or  means  of  doing  the  work.  This 
principle  should  be  well  established  in  mind  before  advantage  is 
taken  of  this  clause.  Work  badly  done  is  justification  for  com- 
plaint by  the  engineer,  and  if  the  bad  work  is  due  to  incompetent 
workmen,  the  clause  may  be  properly  enforced.  It  is  questionable 
if  it  would  be  wise  to  insist  upon  the  clause  against  profane  work- 
men who  did  their  work  well,  but  recourse  should  be  had  to  city 
ordinances  bearing  on  profanity,  indecent  language,  etc. 

(71)  Necessary  conveniences,  properly  secluded  from  public  obser- 
vation, shall  be  constructed  on  the  work  wherever  needed  for  the  use 
of  the  laborers. 

With  some  contractors  this  is  not  necessary;  with  others  it  has 
to  be  rigidly  enforced  by  the  engineer. 


312  SEWER  CONSTRUCTION 

H.  No  claim  for  extra  work  shall  be  considered  or  allowed  unless 
the  same  is  approved  and  ordered  by  the  Engineer  and  the  Board  shall 
authorize  in  writing  such  extra  work.  All  claims  for  extra  work  done 
in  any  month  shall  be  made  to  the  Engineer,  in  writing,  before  the  i5th 
day  of  the  following  month,  or  if  a  specific  claim  is  not  then  possible,  a 
written  notice  shall  be  made  that  extra  work  has  been  done  for  which  a 
claim  will  be  made  as  soon  as  is  practicable. 

And  the  said  Contractor  further  agrees  that  if  he  and  the  said  Board 
are  unable  to  agree  on  the  value  of  such  extra  work,  the  said  Con- 
tractor will  not  in  any  way  interfere  with  or  molest  such  other  person 
or  persons  as  the  said  Board  may  employ  to  do  such  work ;  and  that 
the  said  Contractor  will  suspend  such  part  of  the  work  herein  speci- 
fied, or  will  carry  on  the  same  in  such  manner  as  may  be  ordered  by 
the  said  Engineer,  so  as  to  afford  all  reasonable  facilities  for  doing 
such  extra  work;  and  no  other  damages  or  claim  by  the  said  Con- 
tractor will  be  allowed  therefor,  other  than  an  extension  of  the  time 
specified  in  this  contract  for  the  performance  of  said  suspended 
work  as  much  as  the  same  may  have  been,  in  the  opinion  of  the 
Engineer  (to  be  certified  in  writing),  delayed  by  reason  of  the  per- 
formance of  such  extra  work. 

In  spite  of  this  clause,  the  courts  have  held  that  this  agreement 
may  be  rescinded  by  mutual  consent  and  a  new  oral  agreement 
entered  into  as  to  changes  or  extras.  This  parol  agreement  to 
rescind  may  even  be  inferred  from  the  acts  and  declarations  of  the 
parties.  The  mere  fact  of  assenting  to  extra  work  does  not 
necessarily  render  the  party  of  the  first  part  liable  to  extra  charges, 
but  if  it  has  been  informed  or  must  necessarily  have  known  from 
the  nature  of  the  work  that  the  alterations  would  increase  the 
expense,  silent  assent  may  be  assumed  to  be  an  agreement  to 
the  waiver  of  this  clause.  The  request  of  the  party  of  the  first 
part  for  the  extra  work  is,  however,  essential.  In  the  matter  of  the 
second  part  of  the  clause,  it  is  not  generally  wise  to  employ  work- 
men who  may  come  in  contact  with,  or  affect  in  any  way  the  work 
of,  the  contractor  or  his  workmen.  See  comment  on  (49).  If 
extra  work  is  done  under  the  direction  of  the  engineer,  it  ought  to 
be  entirely  separate  and  distinct  and  away  from  the  work  under 
contract. 


CONTRACT  AND  SPECIFICATIONS  313 

I.  And  the  said  Contractor  hereby  further  agrees  to  give  personal 
attention  to  the  faithful  prosecution  of  the  work,  and  that  he  will  not 
assign  or  sublet  the  work,  or  any  part  thereof,  without  the  previous 
written  consent  of  the  Board  endorsed  on  this  agreement,  but  will  keep 
the  same  under  his  personal  control,  and  will  not  assign,  by  power  of 
attorney,  or  otherwise,  any  of  the  moneys  payable  under  the  agree- 
ment, unless  by  and  with  the  like  consent  of  the  Board  signified  in  like 
manner;  that  no  right  under  this  contract,  nor  to  any  moneys  due  or  to 
become  due  hereunder,  shall  be  asserted  against  the  Board,  or  any 
person  acting  under  them,  or  against  the  city  of or  any  represent- 
ative of  said  city,  by  reason  of  any  so-called  assignment  in  law,  or 
equity,  of  this  contract,  or  any  part  thereof,  unless  such  assignment 
shall  have  been  authorized  by  the  written  consent  of  the  said  Board, 
endorsed  on  this  agreement;  that  no  person,  other  than  the  party 
signing  this  agreement  as  the  party  of  the  second  part  hereto,  now  has 
any  claim  hereunder;  that  no  claim  shall  be  made,  excepting  under  a 
specific  clause  of  this  agreement,  by  any  person  whatever;  and  that 
the  said  Contractor  will  punctually  pay  the  workmen  who  shall  be 
employed  on  the  work. 

This  clause  is  commonly  inserted  and  almost  as  commonly 
neglected.  It  has  been  held  by  the  courts  that  if  it  can  be  proved 
that  the  engineer  knew  that  subcontractors  were  at  work,  and  had 
given  estimates  involving  their  work,  a  waiver  of  this  clause  was 
shown.  An  installment  of  money  not  yet  due  may  be  assigned  to 
material  men,  for  example,  with  due  notice  to  the  party  of  the 
first  part,  and  subsequent  creditors  of  the  contractor  can  receive 
no  advantage  therefrom,  in  spite  of  this  clause.  The  subject  of 
mechanics'  liens  is  pertinent  in  this  relation  and  an  engineer 
should  have  a  general  understanding  of  the  subject.  See  legal 
books  on  liens. 

J.  The  Board  reserves  the  right  of  suspending  the  whole  or  any 
part  of  the  work  herein  contracted  to  be  done,  if  they  shall  deem  it  for 

the  best  interests  of  the  city  of so  to  do,  without  compensation  to 

the  Contractor  for  such  suspension  other  than  extending  the  time  for 
completing  the  work  as  much  as  it  may  have  been  delayed  by  such 
suspension. 

The  courts  have  held  that  even  with  this  clause  the  party  of  the 
first  part  may  be  liable  for  any  injury  which  the  contractor  suffers 
by  reason  of  the  suspension  of  the  work.  The  contractor  by 


3 14  SEWER  CONSTRUCTION 

promptly  protesting  against  an  order  to  suspend  work  puts  him- 
self in  a  better  position  to  be  awarded  damages.  It  is  manifestly 
unfair,  when  once  a  contractor  has  put  in  place  an  expensive  plant 
and  perhaps  done  a  small  amount  of  work,  to  suspend  operations 
causing  direct  loss  to  the  contractor,  and  an  arbitrary  suspension 
may  be  regarded  as  a  breach  of  contract  under  which  the  con- 
tractor would  be  entitled  to  recover  the  cost  of  the  work  actually 
done  with  any  prospective  profits. 

K.  And  the  said  Contractor  further  agrees  to  employ  only  compe- 
tent, skillful  men  to  do  the  work,  giving  preference,  when  other  condi- 
tions are  equal,  to  the  employment  of  residents  of  the  city  of  ...  . 
And  that  whenever  the  Engineer  shall  inform  said  Contractor,  in 
writing,  that  any  man  on  the  work  is,  in  his  opinion,  incompetent,  or 
unfaithful,  or  disorderly,  such  man  shall  be  discharged  from  the  work 
and  shall  not  again  be  employed  on  it. 

See  also  comment  on  (70)  of  Section  G. 

The  contractor  is  in  any  case  bound  by  all  laws  and  statutes  of 
the  state  and  by  all  ordinances  of  the  city  in  which  the  work  is  to 
be  done.  Such  clauses  as  those  relating  to  the  employment  of 
citizens  only,  to  the  length  of  a  day,  to  payment  for  extra  time,  etc., 
he  must  observe  without  specific  clauses  in  the  contract. 

L.  And  the  said  Contractor  further  agrees  that  he  will  commence 
the  work  herein  contracted  to  be  done,  within  twenty  days  from  the 
date  of  this  contract;  that  the  rate  of  progress  shall  be  such  and  that 

he  will  so  conduct  the  said  work  that  on  or  before 

the  whole  work  covered  by  this  contract  and  specifi- 
cations will  be  entirely  completed. 

And  if  said  work  is  not  completed  on  said  date  (or  within  such  further 
time  as  may  be  allowed  by  the  Board  for  such  performance  and 
completion)  the  Contractor  will  pay  to  the  city  the  cost  of  all  engi- 
neering, and  all  inspection  and  superintendence,  that  the  Engineer 
may  have  found  it  necessary  to  incur  after  the  time  fixed  for  the  com- 
pletion of  the  work,  as  aforesaid,  all  of  which  shall  be  determined  by 
the  Engineer,  and  certified  by  him  in  writing,  and  such  certificate, 
when  made,  shall  be  conclusive  upon  the  Contractor,  and  the  Board 
shall  be  and  they  are  hereby  authorized  to  deduct  and  retain  the 
amount  so  certified,  out  of  the  monthly  approximate  estimate  for  work 
done,  and  out  of  the  final  estimate  for  the  work  when  completed. 


CONTRACT  AND   SPECIFICATIONS  315 

There  is  no  doubt  but  that  such  a  clause  as  this,  the  date  being 
clearly  expressed,  is  binding  on  the  contractor.  A  specified  sum 
as  liquidated  damages  is  usually  regarded  as  a  penalty  by  the  courts 
and  will  seldom  be  upheld.  The  courts  prefer  to  inquire  into  the 
actual  value  of  the  damages  incurred,  which,  except  for  the  reasons 
given  in  this  clause,  are  often  visionary  and  unsatisfactory. 

M.  In  case  the  said  Contractor  shall  fail  to  fully  and  entirely,  and 
in  conformity  with  the  provisions  and  conditions  of  this  agreement, 
perform  and  complete  the  said  work,  and  each  and  every  part  and 
appurtenance  thereof,  within  the  time  hereinbefore  specified  for  such 
completion,  or  within  such  further  time  as  may  be  allowed  by  the 
Board  for  such  performance  and  completion,  the  said  Contractor 
shall  and  will  pay  to  the  city  the  sum  of  ten  dollars  ($10)  for  each  and 
every  day  that  the  said  Contractor  shall  be  in  default,  in  addition  to 
the  sum  agreed  to  be  paid  for  additional  cost  of  inspection  and  super- 
intendence, as  provided  in  clause  L  hereof,  which  said  sum  of  ten 
dollars  per  day  is  hereby  agreed  upon,  fixed  and  determined  by  the 
parties  hereto  as  the  damages  (over  and  above  the  additional  cost  of  . 
engineering,  inspectors,  and  superintendence)  which  the  city  will 
suffer  by  reason  of  such  default  and  not  by  way  of  penalty.  And  the 
said  Board  may  deduct  and  retain  said  sum  of  ten  dollars  per  day  out 
of  any  moneys  that  may  be  due  or  become  due  under  this  agreement. 

If  an  amount  stipulated  as  damages  be  so  exorbitant  that  to 
enforce  its  payment  would  be  to  inflict  a  penalty  on  the  party  in 
default,  instead  of  making  good  the  injury  sustained  by  reason  of 
the  breach,  it  will  not  be  enforced.  If  an  additional  compensa- 
tion is  allowed  by  the  contract  for  completion  before  a  certain 
date,  then  a  reduction  for  non-completion  is  proper  and  will  hold 
in  law. 

Waddell  ("  Specifications  and  Contracts,"  page  71)  says  that  a 
clause  such  as  this  is  seldom  enforced  owing  mainly  to  the  charac- 
teristic good  nature  of  engineers  and  to  the  aversion  of  courts  and 
juries  to  its  enforcement.  The  engineer  objects  to  taking  advan- 
tage of  a  contractor  who  has  worked  faithfully  but  has  been 
unfortunate. 

N.  But  neither  an  extension  of  time,  for  any  reason,  beyond  that 
fixed  herein  for  the  completion  of  the  work,  nor  the  doing  and  accept- 
ance of  any  part  of  the  work  called  for  by  this  contract,  shall  be  deemed 


316  SEWER  CONSTRUCTION 

to  be  a  waiver,  by  the  said  Board,  of  the  right  to  abrogate  this  contract 
for  abandonment  or  delay,  in  the  manner  provided  in  the  paragraph 
marked  P  in  this  agreement. 

This  clause  is  intended  to  take  away  from  the  contractor  the 
possibility  of  the  claim  that,  because  he  had  been  granted  an 
extension  of  time,  or  because  a  part  of  the  work  had  been  com- 
pleted and  accepted,  therefore  it  was  tacitly  agreed  that  his  work 
was  satisfactory  and  any  operation  of  clause  P  would  be  without 
reason.  It  is  a  delicate  matter  at  best  to  legally  enforce  clause  P 
without  giving  the  contractor  a  good  basis  for  a  claim  for  damages, 
and  this  clause  makes  the  operation  of  P  more  safe. 

O.  And  the  Board  hereby  agrees  to  pay  or  cause  to  be  paid,  and 
the  Contractor  hereby  agrees  to  receive  the  following  prices,  in  full  com- 
pensation for  furnishing  all  the  materials  and  labor,  and  for  com- 
pleting all  the  work  which  is  necessary  or  proper  to  be  furnished  or 
performed  in  order  to  complete  the  entire  work  in  the  contract  as 
described  and  specified  and  in  said  specifications  and  plans  as 
described  and  shown,  to-wit: 

For  about cubic  yards  of  rock  excavation  in  trenches 

from  the  surface  to  a  depth  not  exceeding  six  (6)  feet,  including 
the  disposal  of  the  material  by  removal  or  otherwise  as  may  be 
required  and  all  work  incidental  thereto,  the  sum  of 

($ ) 

per  cubic  yard. 

For  furnishing  and  laying  about lineal  feet  of  6"  cast  iron 

pipe,  including  all  excavation  and  refilling  and  the  disposal  of  all 
surplus  material;  all  handling  and  laying  of  all  pipe,  furnishing  all 
lead,  yarn  and  other  material  needed  for  making  proper  joints;  all 
pumping  or  bailing  or  otherwise  disposing  of  water;  all  protection 
of  water  and  gas  pipes,  bridges,  culverts,  drains,  etc. ;  all  resurfacing 
and  repaving  of  streets,  and  all  other  incidental  work,  the  sum  of 

(S ) 

per  lineal  foot. 

For  laying  complete  about feet  of  six  (6)  inch  pipe  in 

trench  from  the  surface  to  a  depth  not  exceeding  six  (6)  feet,  including 
excavation  for  manholes  and  other  structures  appertaining  to  the 
sewers  or  drains  and  the  disposal  of  the  material  by  removal,  or  the 
refilling  of  the  trenches  (rolling,  ramming  and  watering  where 
required),  including  sheeting  and  shoring,  bridging  and  fencing, 
and  removal  of  same;  all  pumping  or  bailing  or  otherwise  disposing  of 


CONTRACT  AND   SPECIFICATIONS  317 

water;  all  protection  and  restoration  of  buildings,  bridges,  fences, 
cisterns,  culverts,  drains,  water  and  gas  pipes,  house  drains,  etc.;  all 
resurfacing  and  repaying  of  streets,  accommodation  of  travel  and  all 
other  incidental  work;  including  the  furnishing  of  the  corresponding 
number  of  lineal  feet  of  first  quality,  salt-glazed,  vitrified  sewer  pipe 
of  size  and  quality  specified,  six  (6)  inches  internal  diameter,  including 
all  haulage  and  storage  necessary  before  putting  pipe  in  trench; 
including  the  laying  of  the  corresponding  number  of  lineal  feet  of  pipe 
sewer  including  branches  or  inlets,  gasket  and  tile  stoppers  (cement 
to  be  furnished  by  the  Board),  furnishing  all  tools,  labor,  and  materials 
except  cement,  the  sum  of 

(i , 

per  lineal  foot. 

For  excavation  below  the  sewer  grade  for  the  purpose  of  placing 
timber,  concrete  or  gravel  foundations  under  the  pipe  to  a  depth  not 
greater  than  one  foot  below  said  sewer  grade,  the  sum  of 

($ ) 

per  cubic  yard. 

For  about pounds  of  iron  castings  for  manhole  covers  and 

frames,  as  per  detail  drawings,  including  the  furnishing  all  patterns 
or  molds  necessary,  the  sum  of 

($ ) 

per  pound. 

This  clause  must  not  be  omitted,  since  it  expresses  the  obligation 
of  the  party  of  the  first  part  and  without  it  there  would  be  no 
contract.  Five  items  only  are  given,  but  there  should  be  an 
item  for  every  unit  price  asked  for  in  the  work,  such  as  each 
size  of  pipe,  excavation  at  different  depths,  concrete  for  different 
purposes,  etc. 

P.  The  said  Contractor  further  agrees  that  if  the  work  to  be  done 
under  this  agreement  shall  be  abandoned,  or  if  the  conditions  as  to  the 
rate  of  progress  hereinbefore  specified  are  not  fulfilled,  or  if  this  con- 
tract shall  be  assigned  by  the  Contractor  otherwise  than  is  hereinbefore 
specified,  or  if  at  any  time  the  Engineer  shall  be  of  the  opinion,  and 
shall  so  certify  in  writing  to  the  Board,  that  the  said  work  or  any  part 
thereof  is  unnecessarily  or  unreasonably  delayed,  or  that  the  said  Con- 
tractor is  violating  any  of  the  conditions  or  covenants  of  this  Contract, 
or  executing  said  contract  in  bad  faith,  or  if  the  work  be  not  fully  and 
entirely  completed  within  the  time  herein  stipulated  for  its  completion, 


31 8  SEWER  CONSTRUCTION 

the  said  Board  shall  have  power  to  notify  the  aforesaid  Contractor  to 
discontinue  all  work  or  any  part  thereof,  as  said  Board  may  designate; 
and  the  said  Board  shall  thereupon  have  the  power  to  place  such  and 
so  many  persons,  and  obtain  by  purchase,  or  hire,  such  materials, 
animals,  carts,  wagons,  implements  and  tools,  by  contract  or  otherwise, 
as  the  said  Board  may  deem  necessary  to  complete  the  work  herein 
described,  or  such  part  thereof;  and  to  charge  the  expense  of  said  labor 
and  materials,  animals,  carts,  wagons,  implements  and  tools,  to  the 
aforesaid  Contractor.  And  the  expense  so  charged  shall  be  deducted 
and  paid  by  the  city  out  of  such  moneys  as  either  may  be  due,  or  may 
at  any  time  thereafter  be  due  to  said  Contractor,  under  and  by  virtue 
of  this  agreement,  and  in  case  such  expense  is  less  than  the  sum  which 
would  have  been  payable  under  this  contract  if  the  same  had  been 
completed  by  said  Contractor,  the  Contractor  shall  forfeit  all  claim  to 
the  difference,  and  in  case  such  expense  shall  exceed  the  first  sum, 
then  the  said  Contractor  will  pay  the  amount  of  said  excess  to  the  city 
on  notice  of  said  Board  of  the  excess  so  due. 

Wait  says  that  the  procedure  contemplated  by  this  clause  should 
be  used  only  as  a  last  resort.  Arguments,  persuasion,  coaxing, 
and  threats  and  almost  every  expedient  should  be  used  to  bring 
the  contractor  into  line  with  the  terms  of  his  contract  before  this 
final  step  is  taken.  It  practically  amounts  to  the  annullment  of 
the  contract  by  the  party  of  the  first  part,  which  may  be  to  the  great 
advantage  of  the  contractor.  Haste  in  the  matter  is  certain  to  be 
regretted,  and  every  legitimate  means  should  be  employed  to  keep 
the  contract  whole.  Otherwise  expensive  litigation  and  trouble 
even  with  the  protection  of  this  clause  is  almost  certain  to  follow. 

Q.  And  the  said  Contractor  agrees,  during  the  performance  of  the 
work,  to  take  all  necessary  precautions  and  to  place  proper  guards  for 
the  prevention  of  accidents,  and  to  put  and  keep  at  night  suitable  and 
sufficient  lights,  and  to  indemnify  and  save  harmless  the  said  parties 
of  the  first  part  from  all  damages  and  costs  to  which  they  may  be  put 
by  reason  of  injury  to  the  person  or  property  of  another  resulting  from 
negligence  or  carelessness  in  the  performance  of  the  work,  or  on 
guarding  the  same,  or  from  any  improper  materials  used  in  its  con- 
struction, or  by  or  on  account  of  any  act  or  omission  of  the  said 
Contractor  or  the  agents  thereof,  and  the  Contractor  hereby  agrees 
that  the  whole  or  so  much  of  the  money  due  him  under  the  agreement 
as  may  be  considered  necessary  by  the  Board  may  be  retained  by  the 


CONTRACT  AND  SPECIFICATIONS  319 

city  until  all  suits  or  claims  for  damages,  as  aforesaid,  have  been 
settled  and  evidence  to  that  effect  furnished,  to  the  satisfaction  of  the 
Board. 

Even  with  this  clause,  the  party  of  the  first  part  cannot  entirely 
absolve  itself  from  liability  for  injuries  that  ordinarily  result  from 
the  work  itself.  The  liabilities  assumed  by  a  contractor  are 
usually  those  which  can  be  avoided  by  the  skillful,  careful,  and 
prompt  performance  of  the  contract  or  by  the  foresight,  experi- 
ence, and  knowledge  which  a  contractor  is  supposed  to  possess. 
If  damages  result  from  the  performance  of  the  work  in  the 
manner  required  by  the  contract,  and  not  from  any  negligence 
on  the  part  of  the  contractor,  he  would  probably  not  be  held 
liable  by  the  courts,  even  with  this  clause. 

R.  And  it  is  further  agreed  by  the  Contractor  that  he  will  furnish 
the  Board  with  satisfactory  evidence  that  all  persons  who  have  done 
work  or  furnished  materials  under  this  agreement,  and  who  may  have 
given  written  notice  to  the  Board  before  or  within  20  days  after  the  final 
completion  and  acceptance  of  the  whole  work  under  this  contract, 
that  any  balance  for  such  work  and  materials  is  due  and  unpaid,  have 
been  fully  paid  or  satisfactorily  secured.  And  in  case  such  evidence 
is  not  furnished,  as  aforesaid,  such  amounts  as  may  be  necessary  to 
meet  the  claims  of  the  persons  aforesaid  may  be  retained  from  the 
money  due  the  Contractor  until  the  liabilities  aforesaid  shall  be  fully 
discharged  or  such  notice  withdrawn. 

This  clause  is  required  by  ordinance  to  be  inserted  in  New  York 
City  contracts.  The  right  of  a  municipality  to  interpose  between 
employers  and  the  persons  with  whom  they  deal  for  the  purpose 
of  compelling  the  performance  of  contract  obligations  which  the 
employers  and  the  employees  have  assumed  has  been  questioned. 
But  there  can  be  no  doubt  of  the  popularity  of  this  clause  in  the 
case  of  an  out-of-town  contractor  who  is  inclined  to  neglect  to  pay 
his  local  workmen  and  material  men.  See  also  comment  on  "I." 

S.  The  said  Contractor  hereby  further  agrees  that  the  said  Board 
is  hereby  authorized  to  retain,  out  of  the  moneys  payable  to  the  said 
Contractor  under  this  agreement,  the  sum  of  five  per  cent  on  the 
amount  of  the  contract,  and  to  expend  the  same  as  provided  in 


320  SEWER  CONSTRUCTION 

clause  T  in  making  such  repairs  on  the  line  of  said  work  as  the 
Engineer  may  deem  expedient. 

The  amount  here  given  should  vary  with  the  character  of  the 
work.  If  there  is  competent  inspection  and  no  opportunity  for 
hidden  defects  to  show  themselves  there  is  no  object  in  arbitrarily 
retaining  money  which  the  contractor  has  earned.  But  if  trenches 
may  settle,  if  a  test  of  the  work  can  only  be  had  by  actual  trial 
under  working  conditions,  then  enough  money  to  repair  possible 
defects  may  properly  be  retained. 

T.    The  said  Contractor  further  agrees  that  if,  at  any  period  within 

six  months  from  the  first  day  of or  from  the  date  of  the 

final  completion  of  the  work  contemplated  in  this  contract,  if  such  final 
completion  be  delayed  beyond  that  date,  any  part  of  said  work  shall, 
in  the  opinion  of  the  said  Engineer,  require  repairing,  and  the  said 
Engineer  shall  notify  the  said  Contractor  in  person,  or  by  mail,  to 
make  the  repairs  so  required,  and  if  the  said  Contractor  shall  neglect 
to  make  such  repairs  to  the  satisfaction  of  the  Engineer,  within  five 
days  from  the  date  of  giving  or  mailing  of  such  notice  to  the  said 
Contractor,  his  agent  or  attorney,  then  the  said  Engineer  shall  have 
the  right  to  employ  such  other  persons  as  he  may  deem  proper  to 
make  the  same,  and  the  said  Board  shall  pay  the  expenses  thereof  out 
of  the  sum  retained  by  it  for  that  purpose  as  above  mentioned.  And 
the  said  Board  further  agrees  that,  upon  the  expiration  of  the  said 
period  of  six  months,  provided  the  work  at  the  time  shall  be  in  good 
order,  the  Contractor  shall  at  that  time  receive  the  whole  or  such 
part  of  the  sum  last  aforesaid  as  may  remain  after  the  expense  of 
making  the  said  repairs,  in  the  manner  aforesaid,  shall  have  been 
paid  therefrom. 

Care  must  be  taken  to  have  the  repairs  under  the  meaning  of 
this  clause  such  repairs  only  as  are  due  to  negligence  of  the  con- 
tractor. It  would  not  be  allowable,  after  a  practical  acceptance 
of  a  line  of  sewer  pipe,  with  no  previous  objection  to  the  character 
of  the  work,  to  re-excavate  the  trench  for  the  purpose  of  improving 
the  joints  of  the  pipe.  The  repairs  needed  must  be  obvious  and 
reasonable.  The  period  of  six  months  is  a  proper  one  for  sewer 
work,  since  it  generally  allows  the  lapse  of  the  winter  between  the 
final  completion  of  the  work  and  the  final  acceptance.  On  other 
work  it  might  be  either  too  long  or  too  short. 


CONTRACT  AND   SPECIFICATIONS  321 

U.  In  order  to  enable  the  Contractor  to  prosecute  the  work  advan- 
tageously, the  Engineer  shall  once  a  month,  on  or  about  the  last  day 
of  each  month,  make  an  estimate  in  writing,  of  the  amount  of  work 
done,  and  materials  delivered,  and  of  the  value  thereof,  according 
to  the  items  of  this  contract.  The  first  such  estimate  shall  be  of  the 
amount  or  quantity  and  value  of  the  work  done  and  materials  delivered 
since  the  Contractor  commenced  the  performance  of  this  contract  on 
his  part.  And  every  subsequent  estimate  except  the  final  one  shall 
be  of  the  amount  and  value  of  the  work  done  since  the  last  preceding 
estimate  was  made.  And  such  estimate  shall  not  be  required  to  be 
made  by  strict  measurements  or  with  exactness,  but  this  shall  be 
considered  as  approximate  only.  Upon  such  estimate  being  made, 
the  Board  will  thereupon  pay  to  the  Contractor  eighty  per  cent  of  such 
estimated  value.  And  whenever  the  Contractor  shall  have,  in  the 
opinion  of  the  Engineer,  completely  performed  this  contract  on  his 
part,  the  said  Engineer  shall  so  certify,  in  writing,  to  the  Board  and 
in  his  certificate  shall  state  from  actual  and  exact  measurements 
the  whole  amount  of  work  done  by  the  said  Contractor,  and  also  the 
value  of  this  work  according  to  the  terms  of  the  contract.  And  on  the 
expiration  of  thirty-one  days  after  the  acceptance  by  the  Board  of  the 
work  herein  agreed  to  be  done  by  the  Contractor,  the  said  Board  will 
pay  to  said  Contractor  the  amount  remaining  after  deducting  from 
the  amount  or  value  named  in  the  last  mentioned  certificate  all  such 
sums  as  shall  previously  have  been  paid  to  said  Contractor  under  any 
of  the  provisions  of  the  contract,  and  also  such  sums  of  money  as  by 
the  terms  they  are  authorized  to  reserve  or  retain,  provided  that 
nothing  herein  contained  shall  be  construed  to  affect  the  right  hereby 
reserved  by  said  Board  to  reject  the  whole  or  any  portion  of  the 
aforesaid  work,  should  the  said  certificate  be  found  or  known  to  be 
inconsistent  with  the  terms  of  this  agreement,  or  otherwise  improperly 
given. 

The  percentage  to  be  paid  each  month  should  depend  on  the 
work,  whether  it  can  be  accurately  measured,  whether  of  itself  it 
is  of  value,  or  whether,  except  as  a  part  of  the  completed  work,  it  is 
preparatory  and  incomplete  in  nature.  A  higher  percentage  may 
be  paid  for  material  than  for  labor.  The  engineer  should  not 
yield  to  importunities  of  the  contractor  for  a  large  estimate  on  any 
occasion,  since  retribution  for  such  partiality  is  sure  to  follow.  It 
is  especially  unfortunate  to  have  allowed  the  estimates  to  overrun 
if  the  work  should  be  suspended  or  the  contract  broken. 


322  SEWER  CONSTRUCTION 

V.  The  said  Contractor  further  agrees  not  to  demand  or  be 
entitled  to  receive  payment  for  the  aforesaid  work  or  materials  except 
in  entire  accordance  with  the  manner  set  forth  in  the  agreement,  nor 
unless  each  and  every  one  of  the  promises,  agreements,  specifications, 
forms  and  conditions  herein  set  forth  to  be  observed  by  said  Contractor 
have  been  so  far  kept,  observed  and  fulfilled;  and  the  said  Engineer 
shall  have  given  his  certificate  to  that  effect,  and  the  Board  shall  have 
accepted  his  work. 

This  is  in  effect  saying  that  the  contractor  agrees  to  be  bound 
by  the  terms  of  his  contract,  an  entirely  unnecessary  statement. 
The  clause  is  apparently  superfluous,  but  is  a  proper  legal  provi- 
sion to  secure  a  prior  performance  on  the  part  of  the  contractor, 
and  to  absolve  the  party  of  the  first  part  from  any  obligation 
until  after  the  performance  by  the  party  of  the  second  part. 

W.  It  is  further  expressly  understood  and  agreed  by  and  between 
the  parties  hereto,  that  the  action  of  the  Engineer  by  which  the  said 
Contractor  is  to  be  bound  and  concluded  according  to  the  contract 
shall  be  that  evidenced  by  this  final  certificate;  all  prior  payments 
being  made  merely  upon  estimates  subject  to  the  correction  of  such 
final  certificate;  which  final  certificate  may  be  made  without  notice  to 
the  Contractor  thereof,  or  by  the  measurements  upon  which  the  same 
is  based. 

Wait  says  that  however  much  doubt  there  may  be  that  a  con- 
tractor can  agree  to  abide  the  decision  of  an  engineer,  and  that  his 
decision  shall  be  final,  it  is  fully  settled  that  he  can  make  the 
payment  for  his  work  dependent  upon  the  occurrence  of  some 
event;  and  a  person  may  covenant  that  no  right  to  payment  shall 
accrue  to  the  contractor  and  no  liability  attach  to  the  company 
until  a  third  person  (engineer)  has  decided  the  amount  due.  If 
the  contractor  believes  the  certificate  to  be  withheld  by  fraud, 
impossibility  of  performance,  hindrance  by  the  city,  inducements 
to  the  engineer,  or  a  refusal  to  act  on  the  part  of  the  engineer,  he 
may  appeal  to  the  courts  and  if  his  belief  is  substantiated,  recover 
at  law. 

X.  And  it  is  hereby  expressly  agreed  and  understood  by  and 
between  the  parties  hereto,  that  the  said  Board  shall  not,  nor  shall  any 
department  or  office  of  the  city  of  ,  be  precluded  or  estopped 


CONTRACT  AND   SPECIFICATIONS  323 

by  any  return  or  certificate  made,  or  given,  by  any  Engineer,  inspector, 
or  other  officer,  agent  or  appointee  of  said  Board,  or  said  party  of  the 
first  part,  under  or  in  pursuance  of  anything  in  this  agreement 
contained,  from  at  any  time  showing  the  true  and  correct  amount  and 
character  of  the  work  which  shall  have  been  done,  and  materials 
which  shall  have  been  furnished  by  the  said  Contractor  or  by  any 
other  person  or  persons  under  this  agreement. 

This  clause  is  hardly  necessary,  since  if  the  party  of  the  first 
part  can  show  that  the  certificate  of  the  engineer  has  been  fraudu- 
lently given  they  would  not  be  bound  in  any  case.  Otherwise 
the  engineer's  certificate,  made  honestly,  though  inexactly,  has  been 
held  to  be  equally  conclusive  upon  both  parties.  If  for  example  his 
certificate  includes  extra  work  it  is  binding  and  conclusive,  although 
the  extra  work  may  not  have  been  ordered  in  writing  as  required 
by  the  contract.  Since  the  engineer's  certificate  is  in  the  nature 
of  an  arbitrator's  award,  it  is  generally  held  that  he  cannot  revise 
it.  If  a  mistake  is  found,  a  court  of  equity  on  application  of  the 
engineer  or  by  suit  may  recommit  the  award  to  the  engineer,  or 
both  parties  may  agree  to  abandon  the  award  and  resubmit  the 
questions  to  the  decision  of  another  engineer.  If  there  is  no  fault 
on  the  part  of  the  engineer  and  a  mistake  is  one  arising  from  error 
in  judgment,  the  certificate  cannot  be  recalled. 

IN  WITNESS  WHEREOF  the  said   city  of   ,  by  its  Board  of 

Sewer  Commissioners  duly  authorized,  has  caused  these  presents  to  be 
signed,  and  has  hereunto  set  its  corporate  seal  as  party  of  the  first 

part,   and  the   said   part of  the   second  part  ha also 

hereunto  set hand.. and  seal..,  and  said  city  of   ....,  and 

part hereto  of  the  second  part,  have  executed  this  agreement  in 

triplicate;  one  part  of  which  is  to  remain  with  said  Board,  one  other 
to  be  filed  with  the  Clerk  of  the  city  of  .  .  .  • ,  and  the  third  to  be 
delivered  to  said  party  of  the  second  part;  the  day  and  year  herein 
first  written. 


Board  of  Sewer  Commissioners. 

Contractor. 
Signed  and  sealed  in  the  presence  of 

Witnesses. 


INDEX 


PAGE 

Adams,  tests  of  pipe 13 

Advantages  of  terra-cotta  sewer  pipe 2 

three-foot  pipe  lengths 10 

Altoona,  brick  and  concrete  sewer  at 70 

Analyses  of  sewer  pipe  clay. . 3 

Archer  joint 26 

Area  of  screens 1 53 

Asphalt  joints 25 

Auburn,  cover  for  lamphole 112 

manhole  at 104 

Babcock's  invert  block 33 

Ball  and  socket  joints 23 

Barbour's  experiments  on  earth  pressure 37 

strength  of  pipe 16 

Bell  mouths 185 

alternate  construction  for 193 

at  Philadelphia 187 

at  Providence 191 

near  Boston 187 

Binghamton,  outlet  sewer  at 212 

Birmingham,  screen  at 168 

Blaw  sections  of  concrete  sewers 63 

Bond  for  brick  sewers 48 

Boston,  automatic  regulator  at 178 

bell  mouth  near 187 

catch-basin  at 123 

pile  foundation  at 203 

screen  chamber  at 154 

sewer  outlet  at 217 

Bottoms  of  manholes 90 

Bowser,  alternate  construction  for  bell  mouths 193 

Boxing  in  pipe  against  frost 137 

Branches  for  house  drains 227 

Breslau,  direct  siphon  at 135 

Brick  and  concrete  aqueduct  at  Boston 74 

sewer  at  Altoona 70 

sewer  at  Medford 68 

sewer  at  Melbourne 70 

325 


326  INDEX 

PAGE 

Brick  and  concrete  sewer  on  platform 69 

Brick  for  brick  sewers 29 

sewers 29 

Bricks  required  for  sewers 34 

Brickwork,  cost  of 270 

Bridge  for  crossing  gully 135 

Brockville,  failure  of  manhole  at 90 

Brookline,  automatic  regulator  at 182 

Brooklyn,  section  of  brick  sewer  at 47 

Buenos  Ayres,  direct  siphon  at 148 

inverted  siphon  at 147 

Burlington,  catch-basin  at 127 

sewer  outlet  at 222 

Cambridge,  pile  foundation  at 198 

Caps  for  Y  connections 228 

Carson  trenching  machine 248 

Castings  for  manhole  covers 104 

Catch-basins 113 

at  Boston 1 23 

at  Burlington 127 

at  Columbus 121 

at  Louisville 130 

at  Michigan  city 122 

at  Peoria 125 

at  Philadelphia 128 

at  Providence 122 

at  Washington 130 

at  Wilmington 124 

cleaning  of 132 

gratings  for  inlets  to 116 

size  of 116 

traps  in 119 

Cement  joints  in  sewer  pipe 20 

sewer  pipes 54 

Chenoweth  process  for  concrete  sewers 52 

Chicago  section  of  concrete  sewer 57 

Cleaning  of  catch-basins 132 

Cleveland,  deep  manhole  at 102 

overflow  weir  at 174 

reinforced  concrete  sewer  at 88 

Cloth  used  with  cement  joints 26 

Coffin's  support  for  pipe  joints 21 

Coffin  Valve  Company,  automatic  regulator  of 182 

Coldwater,  arch  blocks  for  sewer  at 56 

Columbus,  catch-basin  at 121 

screens  at 169 


INDEX  327 

PAGE 

Composition  of  sewer  pipe 2 

Concentrated  load  test  on  sewer  pipe 15 

Concrete  and  brick  sewers 67 

Concrete,  cost  of 271 

for  sewer  foundation 197 

Y  branches 228 

pipe,  porosity  of 55 

sewers 52 

sewer  section  at  Chicago 57 

New  York 57 

Swampscott 63 

Truro 61 

Victoria 59 

Washington 57 

sewer  sections  of  Blaw  Collapsible  Steel  Centering  Co '.  . .  .  63 

Concrete  steel,  see  Reinforced  concrete. 

Construction  of  brick  sewer 50 

Contract  and  specifications 279 

Contractor's  profit 277 

Corrugations  on  sewer  pipe 7,  12 

Cost  of  brickwork 270 

cement  pipe 56 

concrete 271 

earthwork 258 

engineering 278 

flush  tanks 277 

manholes 275 

mortar 270 

rock  excavation 262 

sewer  pipe 267 

sheeting 265 

tunnel  excavation 266 

Cover  for  lamphole 112 

Covers  for  manholes 102 

Cradle  for  brick  sewer 51 

sewer    foundations 196 

Cranston,  screen  at 161 

Cross-section  of  manholes 90 

Croyden,  Eng.,  failure  of  pipes  at n 

Deep  sewers,  house  connections  with 230 

Density  of  concrete  for  sewers 63 

Denver  section  of  brick  sewer 46 

Depth  of  drill  holes 255 

Des  Moines,  reinforced  concrete  sewer  at Si 

Die  for  sewer  pipe 6 

Dirt  pans  under  manhole  covers 109 


328  INDEX 

PAGE 

Drilling  in  rock 254 

Drop  tests  on  sewer  pipe 15 

Earth  pressure  on  sewer  arch 37 

Egg-shaped  pipe 8 

Engineering,  cost  of 278 

Estimates  and  costs 257 

Estimates,  preparation  of 241 

Excavation,  cost  of 258 

estimate  of 242 

Experiments  on  strength  of  pipe 13 

Explosives 256 

Failure  of  bell  mouth  at  Nashville 193 

manhole  at  Brockville 90 

walls 94 

pipe  at  Cambridge 18 

Halifax 18 

Oberlin 19 

Toronto 18 

Floor  area  of  manholes 93 

Flush  tanks,  cost  of 277 

Form  of  notes 240 

Forms  for  concrete  sewer  at  Medford 68 

New  York 59 

South  Bend 85 

sewers  at  Chicago 57 

Swampscott 63 

Truro 63 

Victoria 61 

of  steel  ribbon 52 

Formula  for  the  thickness  of  pipe 16 

Foundation  for  manhole 06 

Foundations 195 

Frames  and  covers  for  manholes 102 

Frost,  to  protect  pipes  against 137 

Fuertes,  manhole  cover  designed  by 1 04 

Glaze  on  sewer  pipe 8 

Grade  boards  for  sewer  construction 238 

Grade  of  house  drains 230 

Gratings  for  storm  water  inlets 1 16 

Gravel  for  pipe  foundations 105 

Harrisburg,  automatic  regulator  at 180 

reinforced  concrete  sewer  at 79 

Hassal  joint 26 


INDEX  329 


PAGE 

Hastings  on  failure  of  pipes  .........................  jg 

Hering,  bridge  for  crossing  gully,  designed  by  ..........................  137 

lock  for  manhole,  designed  by  ........................  IO8 

House  connections  ...................................................  22y 

drains,  grade  of  ..........................................  230 

size  of  ................................................  229 

traps  on  ...............................................  230 

Howe,  tests  of  sewer  pipe  ............................................  ^ 

Hydrostatic  tests  of  pipe  ...........................................  !^ 

Inlets  for  catch-basins  ...............................................  j  !  •? 

Inlet  to  storm  sewer  at  Warsaw  .......................................  130 

Tarrytown  .....................................  131 

Intersection  of  manhole  and  sewer  .....................................  06 

sewers  ................................................  185 

Invert  blocks  .......................................................  30 

Ithaca,  dirt  pans  at  .................................................  109 

inverted  siphon  at  ..............................  ............  147,  151 

lock  for  manhole  at  ...........................................  108 

outfall  sewer  at  ..............................................  220 

rod  screen  at  .................................................  164 

screen  chamber  at.  .  .  .........................................  154 

Jackson  Reinforced  Pipe  Company  ....................................  75 

Jersey  City  reinforced  concrete  aqueduct  ...............................  79 

Joints  made  on  bank  ................................................  21 

of  asphalt  ....................................................  25 

pine  tar  ....................................................  25 

sulphur  and  sand  ...........................................  22,  24 

Junction  chamber  at  Minneapolis  .....................................  193 

Keating  on  failure  of  pipe  ............................................  18 

Kilns  for  sewer  pipe  manufacture  .....................................  7 

Lampholes  .........................................................  in 

Latham's  formula  for  thickness  .......................................  36 

invert  block  ...............................................  31 

Leakage  through  cement  joints  ...........  .............................  21  . 

concrete  pipes  .......................................  55 

Leaping  weir  at  Milwaukee  ...........................................  172 

Leaping  weir,  theory  of  ..............................................  172 

Length  of  sewer  pipe  ................................................  10 

Lidgerwood  cableway  ...........................................  .....  250 

Location  of  manholes  ...............................................  89,  236 

storm  water  inlets  ........................................  113 

Y  branches  ..............................................  229 


330  INDEX 

PAGE 

Locks  for  manhole  covers 107 

at  Ithaca 108 

Salt  Lake  City 109 

Los  Angeles,  inverted  siphon  at 148 

sewer  outlet  at 223 

Louisville,  catch-basin  at 130 

Lynn,  pile  foundation  at 199 

Manchester,  screen  chamber  at 157 

Manhole  cover  at  Auburn 104 

Manholes 89 

Manhole  at  Cleveland 102 

Melbourne 101 

bottoms  of 90 

cost  of 275 

cover  at  Santos 104 

cross-sections  of 90 

dirt  pans  under  covers 109 

failure  of  walls  of 94 

floor  area  of 93 

for  sewers  on  different  levels 97 

shallow  sewers 90 

foundation  for 9^ 

frames  and  covers 102 

location  on  sewer  line 235 

locks  for  covers i°7 

on  large  brick  sewers 96 

Sessions  Iron  Foundry  cover 104 

thickness  of  walls  of 94 

Manilla,  timber  foundation  for  sewer  at 196 

Map  for  sewer  location 235 

Marlborough,  screen  at 160 

Maximum  and  minimum  strength  of  pipe 17 

Medford,  brick  and  concrete  sewer  at 68 

Melbourne,  brick  and  concrete  sewer  at 7° 

deep  manhole  at I01 

Mesh  for  screens l63 

Mexico,  reinforced  concrete  aqueduct  at 75 

Michigan  City,  catch-basin  at I22 

Milwaukee,  leaping  weir  at 1  ~2 

Minneapolis,  junction  chamber  at J93 

Moore  machine 252 

Moore's  design  for  outfall  sewer 212 

theory  of  leaping  weir J72 

Mortar,  cost  of 27° 

Mortar  for  brick  sewers 5° 


INDEX  331 

PAGE 

Nashville,  failure  of  bell  mouth  at 193 

Newark,  plate  screen  at 164 

New  London,  sewer  outlet  at 220 

New  Orleans,  inverted  siphon  at 140 

section  of  brick  sewer 45 

New  Rochelle,  sewer  outlet  at 220 

Newton,  failure  of  sewer  at 36 

inverted  siphon  at 140 

New  York,  inverted  siphon  at 146 

pile  foundation  at 204 

reinforced  concrete  sewer  at 80 

section  of  concrete  sewer 57 

sewer  outlet  at 217 

Niagara  Falls,  outfall  sewer  at 212 

Norfolk,  direct  siphon  at 133 

Notes  for  sewer  construction 240 

Number  of  bricks  in  sewers 34 

house  connections 227 


Oakland,  concrete  conduits  at 53 

Offset  line  to  sewer 237 

Old  Orchard  Beach,  outfall  sewer  at 222 

Ontario  Insane  Hospital,  screen  at 166 

Ottawa  section  of  brick  sewer 45 

Outfall  sewers 211 

at  Binghamton 212 

at  Boston 217 

at  Burlington 222 

at  Ithaca 221 

at  Los  Angeles 223 

at  New  London 220 

at  New  Rochelle 220 

at  Niagara  Falls 212 

at  New  York 217 

at  Old  Orchard  Beach 222 

at  Philadelphia 214 

at  Spring  Lake 220 

at  Toronto 223 

designed  by  Moore 212 

Overflows  for  storm  water 17° 

Overflow  weir  at  Cleveland i?4 

at  Providence 176 

at  Rochester 170,  *77 

Parker  on  failure  of  pipe 18 

Paving  brick  for  invert 30 


332  INDEX 

PAGE 

Peoria,  catch-basin  at 125 

Philadelphia,  bell-mouth  at 187 

catch-basin  at 1 28 

reinforced  concrete  sewer  at 82 

sewer  outlet  at 214 

sections  of  masonry 38 

Pile  foundation  at  Boston 203 

Cambridge 198 

Lynn 199 

New  York 204 

St.  Paul 206 

Troy 199 

Piles  for  sewer  foundation 198 

Pine  tar  joints 25 

Pipes,  cost  of 267 

Pipes  for  sewers,  see  Sewer  pipe. 

Plank  for  pipe  foundations 195 

Plates,  perforated  for  screens 164 

Platform  for  sewer  foundation 196 

foundation  at  Manilla 196 

Providence,  bell-mouth  at 171 

catch-basin  at 122 

inverted  siphon  at 149 

overflow  weir *at 176 

reinforced  concrete  sewer  at 76 

screen  chamber  at 1 59 

wooden  screen  at 167 

Portland,  Me.,  sewer  pipe  plant  at 2 

Potter  machine 252 

on  failure  of  pipe 19 

Press  for  sewer  pipe 6 

Profit  of  contractor 277 

Pug  mill  for  pipe  manufacture 3 

Pullman,  screen  at 167 

Ramsome  process  for  concrete  sewers 

Richmond,  screen  at 167 

Records  of  house  connections 229 

Y  branches 

Regulator  at  Boston 1 78 

Brookline 182 

Harrisburg 180 

Worcester 180 

of  Coffin  Valve  Company 182 

Reinforced  concrete  sewers 75 

at  Cleveland 88 

aqueduct  at  Jersey  City 79 


INDEX  333 

PAGE 

Reinforced  concrete  aqueduct,  Mexico 75 

sewer  at  Des  Moines 81 

sewer  at  Harrisburg 79 

sewer  at  New  York 80 

sewer  at  Philadelphia 82 

sewer  at  Providence 76 

sewer  at  St.  Louis 82 

sewer  at  South  Bend 85 

sewer  at  Wilmington 76 

Roanoke,  inverted  siphon  at 140 

Rochester,  overflow  weir  at 170,  177 

sections  of  brick  sewers 47 

Rock  excavation,  cost  of 262 

Rock  trenches,  house  connections  in 233 

Rock  trenching 252 

Rods  for  screens 164 

Roll  mill  for  pipe  manufacture 4 

Rowlock  bond  for  brick  sewers 48 

Rust  on  failure  of  pipe 18 

Saddle  piles 198 

St.  Louis,  manufacture  of  sewer  pipe  at 2 

reinforced  concrete  sewer  at 82 

steps  in  sewer  at 101 

St.  Paul,  pile  foundation  at 206 

Salt,  used  in  pipe  kilns 8 

Salt  Lake  City,  lock  for  manhole  at 109 

Santos,  manhole  cover  at 104 

Screens 153 

at  Birmingham 168 

at  Columbus 169 

at  Cranston 161 

at  Ithaca 164 

at  Marlborough 161 

at  Newark 164 

at  Ontario  Insane  Hospital 166 

at  Providence 167 

at  Pullman 167 

at  Richmond ' 167 

at  Wayne 163 

at  White  Plains 160 

at  Worcester  State  Hospital 164 

Screen  chambers 154 

at  Boston 154 

at  Ithaca 154 

at  Manchester 157 

at  Providence 159 


334  INDEX 

PAGE 

Sections  of  Philadelphia  sewers 38 

Sessions  Foundry  Co.,  manhole  cover  of 104 

Settlement  of  sewer  embankment 208 

Sewer  pipe,  advantages  of 2 

analysis  of  material  for 3 

composition  of 2 

length  of 10 

sizes  of 10 

thickness  of 10 

Shedd,  tests  of  pipe 13 

Sheeting,  cost  of 265 

Sheeting  for  trenches 246 

Shrinking  of  pipes  in  burning 8 

Siphons 133 

at  Breslau 135 

at  Buenos  Ayres 147 

at  Ithaca 147 

at  Los  Angeles 148 

at  New  Orleans 140 

at  Newton 140 

at  New  York 146 

at  Norfolk 133 

at  Providence 149 

at  Roanoke 140 

at  Springfield 142 

at  Woonsocket 142 

Size  of  catch-basins 1 16 

Size  of  house  drains 229 

Sizes  of  pipe 10 

Slants  for  house  connections 228 

Sockets,  sizes  of 1 1 

South  Bend,  reinforced  concrete  sewer  at 85 

thickness  of  sewer  at 36 

Specifications,  forms  of 286 

Spikes  to  mark  offset  line 237 

Springfield,  inverted  siphon  at 142 

thickness  of  sewer  at 36 

Spring  Lake,  sewer  outlet  at 220 

Stanford  joints 22 

Steel  outfall  sewer  at  Toronto 223 

Steps  in  sewer  at  manhole 101 

Storm  water  overflows i?° 

Strap  iron  bond  for  brick  sewers 5° 

Strength  of  double  strength  pipe 16 

Strength  of  standard  pipe 16 

Sudbury  river  aqueduct .  .  .  74 

Sulphur  and  sand  joints 22,  24 


INDEX  335 


PAGE 


Surveying 235 

Swampscott  section  of  concrete  sewer 63 

Sykes  joint 26 

Table  of  reinforcement  for  cement  pipes 76 

Table  of  socket  space 12 

Table  of  thickness  of  pipe n 

Talbot's  invert  block 30 

Tarrytown,  storm  water  inlet  at 131 

Temperature  of  pipe  kilns 8 

Tensile  strength  of  vitrified  clay 14 

Thickness  of  brick  sewers 35 

Thickness  of  cement  pipe 56 

Thickness  of  manhole  walls 94 

Thickness  of  sewer  pipe 10 

Toronto,  steel  outfall  sewer  at 223 

Trap   in  catch-basin  at  Columbus 121 

for  catch-basins 119 

on  house  drain 230 

Trenching 245 

Troy,  pile  foundation  at 199 

Truro  section  of  concrete  sewer 61 

Tunnel  excavation,  cost  of 266 

Uniform  load  tests  on  sewer  pipe 15 

U.  S.  G.  S.  experiments  on  concrete  pipe 55 

Victoria  section  of  concrete  sewer 59 

Warsaw,  storm  water  inlet  at 130 

Washington,  catch-basin  at 130 

Washington  sections  of  brick  sewers 45 

Washington  sections  of  concrete  sewers 57 

Wayne,  screen  at 163 

White  Plains,  screen  at 160 

Width  of  trench 245 

Wilmington,  catch-basin  at 124 

reinforced  concrete  sewer  at 76 

Woburn,  automatic  regulator  at 185 

Wooden  pipes  for  outfall  sewer 220 

Woonsocket,  inverted  siphon  at 142 

Worcester,  automatic  regulator 180 

Worcester  State  Hospital,  screen  at 164 

Y  branches,  records  of 243 


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Johnson's  Statics  by  Algebraic  and  Graphic  Methods 8vo,  2  oo 

Kellaway's  How  to  Lay  Out  Suburban  Home  Grounds 8vo,  2  oo 

Kidder's  Architects'  and  Builders'  Pocket-book i6mo,  mor.  5  oo 

Maire's  Modern  Pigments  and  their  Vehicles i2mo,  2  oo 

Merrill's  Non-metallic  Minerals:    Their  Occurrence  and  Uses 8vo,  4  oo 

Stones  for  Building  and  Decoration 8vo,  5  oo 

Monckton's  Stair-building 4to,  4  oo 

Patton's  Practical  Treatise  on  Foundations 8vo,  5  oo 

Peabody's  Naval  Architecture 8vo,  7  50 

Rice's  Concrete-block  Manufacture 8vo,  2  oo 

Richey's  Handbook  for  Superintendents  of  Construction i6mo,  mor.  4  oo 

*  Building  Mechanics'  Ready  Reference  Book: 

*  Building   Foreman's  Pocket   Book  and  Ready  Reference.     (In 
Press.) 


*  Carpenters'  and  Woodworkers'  Edition i6mo,  mor. 

*  Cement  Workers  and  Plasterer's  Edition i6mo,  mor. 

*  Plumbers',  Steam-Filters',  and  Tinners'  Edition  ....  i6mo,  mor. 


*  Stone-  and  Brick-masons'  Edition i6mo,  mor. 

Sabin's  House  Painting 12  mo, 

Industrial  and  Artistic  Technology  of  Paints  and  Varnish 8vo,  3  oo 

Siebert  and  Biggin's  Modern  Stone-cutting  and  Masonry 8vo,  i  50 

Snow's  Principal  Species  of  Wood 8vo,  3  50 

Towne's  Locks  and  Builders'  Hardware iSmo,  mor,  3  oo 

Wait's  Engineering  and  Architectural  Jurisprudence 8vo,  6  oo 

Sheep,  6  50 

Law  of  Contracts 8vo,  3  oo 

Law  of  Operations  Preliminary  to  Construction  in  Engineering  and  Archi- 
tecture.  8vo,  5  oo 

Sheep,  5  SO 

Wilson's  Air  Conditioning i2mo,  i  50 

Worcester  and  Atkinson's  Small  Hospitals,  Establishment  and  Maintenance, 
Suggestions  for  Hospital  Architecture,  with  Plans  for  a  Small  Hospital 

1 2 mo,  i  25 

ARMY  AND  NAVY. 

Seniadou's  Smokeless  Powder,  Nitro-cellulose,  and  the  Theory  of  the  Cellulose 

Molecule I2mo,  2  50 

Chase's  Art  of  Pattern  Making i2mo,  2  50 

Screw  Propellers  and  Marine  Propulsion 8vo,  3  oo 

*  Cloke's  Enlisted  Specialist's  Examiner 8vo,  2  oo 

Gunner's  Examiner 8vo,  i  50 

Craig's  Azimuth 4to,  3  50 

Crehore  and  Squier's  Polarizing  Photo-chronograph 8vo,  3  oo 

*  Davis's  Elements  of  Law 8vo,  2  50 

*  Treatise  on  the  Military  Law  of  United  States 8vo,  7  oo 

Sheep  7  50 

De  Brack's  Cavalry  Outpost  Duties.     (Carr) 24mo,  mor.  2  oo 

*  Dudley's  Military  Law  and  the  Procedure  of  Courts-martial..  .  Large  i2mo,  2  50 
Durand's  Resistance  and  Propulsion  of  Ships 8vo,  5  oo 


*  Dyer's  Handbook  of  Light  Artillery i2mo,  3  oo 

Eissler's  Modern  High  Explosives 8vo,  4  oo 

*  Fiebeger's  Text-book  on  Field  Fortification Large  i2mo,  2  oo 

Hamilton  and  Bond's  The  Gunner's  Catechism i8mo,  i  oo 

*  Hoff 's  Elementary  Naval  Tactics 8vo,  r  50 

Ingalls's  Handbook  of  Problems  in  Direct  Fire. 8vo,  4  oo 

*  Lissak's  Ordnance  and  Gunnery 8vo,  6  oo 

*  Ludlow's  Logarithmic  and  Trigonometric  Tables 8vo,  i  oo 

*  Lyons's  Treatise  on  Electromagnetic  Phenomena.  Vols.  I.  and  II..  8vo,  each,  6  oo 

*  Mahan's  Permanent  Fortifications.     (Mercur) 8vo,  half  mor.  7  50 

Manual  for  Courts-martial i6mo,  mor.  i  50 

*  Mercur's  Attack  of  Fortified  Places I2mo,  2  oo 

*  Elements  of  the  Art  of  War 8vo,  4  oo 

Metcalf's  Cost  of  Manufactures — And  the  Administration  of  Workshops.  .8vo,  5  oo 

Nixon's  Adjutants'  Manual 24mo,  i  oo 

Peabody's  Naval  Architecture 8vo,  7  50 

*  Phelps's  Practical  Marine  Surveying 8vo,  2  50 

Putnam's  Nautical  Charts 8vo,  2  oo 

Sharpe's  Art  of  Subsisting  Armies  in  War , i8mo,  mor.  i  50 

*  Tupes  and  Poole's  Manual  of  Bayonet  Exercises  and    Musketry  Fencing. 

24010,  leather,  50 

*  Weaver's  Military  Explosives 8vo,  3  oo 

Woodhull's  Notes  on  Military  Hygiene. i6mo,  x  50 


ASSAYING. 

Betts's  Lead  Refining  by  Electrolysis 8vo,  4  oo 

Fletcher's  Practical  Instructions  in  Quantitative  Assaying  with  the  Blowpipe. 

1 6 mo,  mor.  i  50 

Furman's  Manual  of  Practical  Assaying v 8vo,  3  oo 

Lodge's  Notes  on  Assaying  and  Metallurgical  Laboratory  Experiments ....  8vo,  3  oo 

Low's  Technical  Methods  of  Ore  Analysis 8vo,  3  oo 

Miller's  Cyanide  Process i2mo,  i  oo 

Manual  of  Assaying I2mo,  i  oo 

Minet's  Production  of  Aluminum  and  its  Industrial  Use.     (Waldo) i2mo,  2  50 

O'Driscoll's  Notes  on  the  Treatment  of  Gold  Ores 8vo,  2  oo 

Ricketts  and  Miller's  Notes  on  Assaying 8vo,  3  oo 

Robine  and  Lenglen's  Cyanide  Industry.     (Le  Clerc) 8vo,  4  oo 

Ulke's  Modern  Electrolytic  Copper  Refining , 8vo,  3  oo 

Wilson's  Chlorination  Process i2mo,  i  50 

Cyanide  Processes I2mo  r   50 


ASTRONOMY. 


Comstock's  Field  Astronomy  for  Engineers 8vo,  2  50 

Craig's  Azimuth 4to,  3  50 

Crandall's  Text-book  on  Geodesy  and  Least  Squares 8vo,  3  oo 

Doolittle's  Treatise  on  Practical  Astronomy 8vo,  4  oo 

Gore's  Elements  of  Geodesy 8vo,  2  50 

Hayford's  Text-book  of  Geodetic  Astronomy 8vo,  3  oo 

Merriman's  Elements  of  Precise  Surveying  and  Geodesy. 8vo,  2  50 

*  Michie  and  Harlow's  Practical  Astronomy 8vo,  3  oo 

Rust's  Ex-meridian  Altitude,  Azimuth  and  Star- Finding  Tables 8vo,  5  oo 

*  White's  Elements  of  Theoretical  and  Descriptive  Astronomy i2mo,  2  oo 


CHEMISTRY. 

*  Abderhalden's  Physiological  Chemistry  in  Thirty  Lectures.    (Hall  and  Defren) 

8vo,  5  oo 

*  Abegg's  Theory  of  Electrolytic  Dissociation,    (von  Ende) izmo,  i  25 

Alexeyeff's  General  Principles  of  Organic  Syntheses.     (Matthews) 8vo,  3  oo 

Allen's  Tables  for  Iron  Analysis 8vo,  3  oo 

Arnold's  Compendium  of  Chemistry.     (Mandel  1 Large  i2mo,  3  50 

Association  of  State  and  National  Food  and  Dairy  Departments,  Hartford, 

Meeting,  1906 8vo,  3  oo 

Jamestown  Meeting,  1907 8vo,  3  oo 

Austen's  Notes  for  Chemical  Students i2mo,  i  50 

Baskerville's  Chemical  Elements.     (In  Preparation.) 

Bernadou's  Smokeless  Powder. — Nitro-cellulose,  and  Theory  of  the  Cellulose 

Molecule i2mo-  2  50 

Biltz's  Chemical  Preparations.     (Hall  and  Blanchard).     (In  Press.) 

*  Blanchard's  Synthetic  Inorganic  Chemistry i2mo,  i  oo 

*  Browning's  Introduction  to  the  Rarer  Elements 8vo,  i  50 

Brush  and  Penfield's  Manual  of  Determinative  Mineralogy 8vo,  4  oo 

*  Claassen's  Beet-sugar  Manufacture.     (Hall  and  Rolfe) 8vo,  3  oo 

Classen's  Quantitative  Chemical  Analysis  by  Electrolysis.    (Boltwood)..  .8vo,  3  oo 

Cohn's  Indicators  and  Test-papers i2mo,  2  oo 

Tests  and  Reagents 8vo,  3  oo 

*  Danneel's  Electrochemistry.     (Merriam) i2mo,  i   25 

Dannerth's  Methods  of  Textile  Chemistry i2mo,  2  oo 

Duhem's  Thermodynamics  and  Chemistry.     (Burgess) 8vo,  4  oo 

Eakle's  Mineral  Tables  for  the  Determination  of  Minerals  by  their  Physical 

Properties 8vo,  i  25 

Eissler's  Modern  High  Explosives 8vo,  4  oo 

Effront's  Enzymes  and  their  Applications.     (Prescott) 8vo,  3  oo 

Erdmann's  Introduction  to  Chemical  Preparations.     (Dunlap) i2mo,  i   25 

*  Fischer's  Physiology  of  Alimentation Large  i2mo,  2  oo 

Fletcher's  Practical  Instructions  in  Quantitative  Assaying  with  the  Blowpipe. 

I2mo,  mor.  i   50 

Fowler's  Sewage  Works  Analyses i2mo,  2  oo 

Fresenius's  Manual  of  Qualitative  Chemical  Analysis.     (Wells). 8vo,  5  oo 

Manual  of  Qualitative  Chemical  Analysis.  Part  I.  Descriptive.  (Wells)  8vo,  3  oo 

Quantitative  Chemical  Analysis.     (Cohn)     2  vols 8vo,  12  50 

When  Sold  Separately,  Vol.  I,  $6.     Vol.  II,  $8. 

Fuertes's  Water  and  Public  Health I2mo,  i  50 

Furman's  Manual  of  Practical  Assaying 8vo,  3  oo 

*  Getman's  Exercises  in  Physical  Chemistry i2mo,  2  oo 

Gill's  Gas  and  Fuel  Analysis  for  Engineers i2mo,  i  25 

*  Gooch  and  Browning's  Outlines  of  Qualitative  Chemical  Analysis. 

Large  i2mo,  i   25 

Grotenfelt's  Principles  of  Modern  Dairy  Practice.     (Woll) i2mo,  2  oo 

Groth's  Introduction  to  Chenrcal  Crystallography  (Marshall) i2mo,  i  25 

Hammarsten's  Text-book  of  Physiological  Chemistry.     (Mandel) 8vo,  4  oo 

Hanausek's  Microscopy  of  Technical  Products.     (Winton) 8vo,  5  oo 

*  Haskins  and  Macleod's  Organic  Chemistry izmo,  2  oo 

Helm's  Principles  of  Mathematical  Chemistry.     (Morgan) i2mo,  i  50 

Bering's  Ready  Reference  Tables  (Conversion  Factors) i6mo,  mor.  2  50 

*  Herrick's  Denatured  or  Industrial  Alcohol 8vo,  4  oo 

Hinds's  Inorganic  Chemistry 8vo,  3  oo 

*  Laboratory  Manual  for  Students I2mo,  i  oo 

*  Holleman's    Laboratory   Manual    of   Organic    Chemistry  for   Beginners. 

(Walker) 12m°.  x  °° 

Text-book  of  Inorganic  Chemistry.     (Cooper) 8vo,  2  50 

Text-book  of  Organic  Chemistry.     (Walker  and  Mott) 8vo,  2  50 

4 


olley  and  Ladd's  Analysis  of  Mixed  Paints,  Color  Pigments,  and  Varnishes. 

Large  12 mo,  2  50 

Hopkins's  Oil-chemists'  Handbook 8vo,  3  oo 

Iddings's  Rock  Minerals 8yo,  5  oo 

Jackson's  Directions  for  Laboratory  Work  in  Physiological  Chemistry.  .8vo,  I  25 

Johannsen's  Determination  of  Rock-forming  Minerals  in  Thin  Sections. .  .8vo,  4  oo 
Johnson's  Chemical  Analysis  of  Special  Steel.     Steel-making.     (Alloys  and 
Graphite.)     (In  Press.) 

Keep's  Cast  Iron 8vo,  2  50 

Ladd's  Manual  of  Quantitative  Chemical  Analysis I2mo,  i  oo 

i,andauer's  Spectrum  Analysis.     (Tingle) 8vo,  3  oo 

*  ^angworthy  and   Austen's  Occurrence   of  Aluminium  in  Vegetable  Prod- 

ucts, Animal  Products,  and  Natural  Waters 8vo,  2  oo 

Lassar-Cohn's  Application  of  Some  General  Reactions  to  Investigations  in 

Organic  Chemistry.  (Tingle) i2mo,  i  oo 

Leach's  Inspection  and  Analysis  of  Food  with  Special  Reference  to  State 

Control 8vo,  7  50 

Lob's  Electrochemistry  of  Organic  Compounds.  (Lorenz) 8vo,  3  oo 

Lodge's  Notes  on  Assaying  and  Metallurgical  Laboratory  Experiments. ..  .8vo,  3  oo 

Low's  Technical  Method  of  Ore  Analysis 8vo,  3  oo 

Lunge's  Techno-chemical  Analysis.  (Cohn) i2mo,  i  oo 

*  McKay  and  Larsen's  Principles  and  Practice  of  Butter-making 8vo,  i  50 

Maire's  Modern  Pigments  and  their  Vehicles i2mo,  2  oo 

Mandel's  Handbook  for  Bio-chemical  Laboratory i2mo.  i  50 

*  Martin's  Laboratory  Guide  to  Qualitative  Analysis  with  the  Blowpipe .  .  i2mo,  60 
Mason's  Examination  of  Water.     (Chemical  and  Bacteriological.) ..     .  i2mo,  i  25 

Water-supply.     (Considered  Principally  from   a   Sanitary   Standpoint. 

8vo,  4  oo 

Mathewson's  Chemical  Theory  for  First  Year  College  Students.     (In  Press). 

Matthews's  Textile  Fibres.     2d  Edition,  Rewritten 8vo,  4  oo 

*  Meyer's  Determination  of  Radicle?  in  Carbon  Compounds.     (Tingle). .  i2mo,  25 
Miller's  Cyanide  Process : I2mo,  oo 

Manual  of  Assaying i2mo,  oo 

Minet's  Production  of  Aluminum  and  its  Industrial  Use.  (Waldo) i2mo,  50 

Mixter's  Elementary  Text-book  of  Chemistry I2mo,  50 

Morgan's  Elements  of  Physical  Chemistry I2mo,  oo 

Outline  of  the  Theory  of  Solutions  and  its  Results I2mo,  oo 

*  Physical  Chemistry  for  Electrical  Engineers i2mo,  50 

Morse's  Calculations  used  in  Cane-sugar  Factories i6mo,  mor.  50 

*  Muir's  History  of  Chemical  Theories  and  Laws 8vo,  4  oo 

Mulliken's  General  Method  for  the  Identification  of  Pure  Organic  Compounds. 

Vol.  I Large  8vo,  5  oo 

O'Driscoll's  Notes  on  the  Treatment  of  Gold  Ores 8vo,  2  oo 

Ostwald's  Conversations  on  Chemistry.     Part  One.     (Ramsey) I2mo,  i  50 

Part  Two.     (TurnbuU) i2mo,  2  oo 

*  Palmer's  Practical  Test  Book  of  Chemistry i2mo,  i  oo 

*  Pauli's  Physical  Chemistry  in  the  Service  of  Medicine.     (Fischer") I2mo,  i  25 

*  Penfield's  Notes  on  Determinative  Mineralogy  and  Record  of  Mineral  Tests. 

8vo,  paper,  50 
Tables  of  Minerals,  Including  the   Use   of  Minerals  and  Statistics  of 

Domestic  Production 8vo,  i  oo 

Pictet's  Alkaloids  and  their  Chemical  Constitution.     (Biddle).  .    8vo,  5  oo 

Poole's  Calorific  Power  of  Fuels 8vo,  3  oo 

Prescott  and  Winslow's  Elements  of  Water  Bacteriology,  with  Special  Refer- 
ence to  Sanitary  Water  Analysis i2mo,  i  50 

*  Reisig's  Guide  to  Piece-dyeing 8vo,  25  oo 

Richards  and  Woodman's  Air,  Water,  and  Food  from  a  Sanitary  Standpoint.. 8 vo,  2  oo 

Ricketts  and  Miller's  Notes  on  Assaying 8vo,  3  oo 

Rideal's  Disinfection  and  the  Preservation  of  Food 8vo,  4  oo 

Sewage  and  the  Bacterial  Purification  of  Sewage 8vo,  4  oo 

5 


Riggs's  Elementary  Manual  for  the  Chemical  Laboratory 8vo,  i  25 

Robine  and  Lenglen's  Cyanide  Industry.     (Le  Clerc) 8vo,  4  oo 

Ruddiman's  Incompatibilities  in  Prescriptions 8vo,  2  oo 

Whys  in  Pharmacy J2mo,  i  oo 

Ruer's  Elements  of  Metallography.     (Mathewson)     (In  Preparation.) 

Sabin's  Industrial  and  Artistic  Technology  of  Paints  and  Varnish 8vo,  3  oo 

Salkowski's  Physiological  and  Pathological  Chemistry.     (Orndorff) Svo,  2  50 

Schimpf's  Essentials  of  Volumetric  Analysis i2mo,  i  25 

*  Qualitative  Chemical  Analysis Svo,  i  25 

Text-book  of  Volumetric  Analysis I2mo,  2  50 

Smith's  Lecture  Notes  on  Chemistry  for  Dental  Students 8vo,  2  50 

Spencer's  Handbook  for  Cane  Sugar  Manufacturers i6mo,  mor.  3  oo 

Handbook  for  Chemists  of  Beet-sugar  Houses i6mo,  mor.  3  oo 

Stockbridge's  Rocks  and  Soils 8vo,  2  50 

*  Tillman's  Descriptive  General  Chemistry 8vo,  3  oo 

*  Elementary  Lessons  in  Heat 8vo,  i  50 

Treadwell's  Qualitative  Analysis.     (Hall) f 8vo,  3  oo 

Quantitative  Analysis.     (Hall) 8vo,  4  oo 

Turneaure  and  Russell's  Public  Water-supplies 8vo,  5  oo 

Van  Deventer's  Physical  Chemistry  for  Beginners.     (Boltwood) i2mo,  i  50 

Venable's  Methods  and  Devices  for  Bacterial  Treatment  of  Sewage Svo,  3  oo 

Ward  and  Whipple's  Freshwater  Biology.     (In  Press.) 

Ware's  Beet-sugar  Manufacture  and  Refining.     Vol.  I Small  Svo,  4  oo 

Vol.11 Small8vo,  5  co 

Washington's  Manual  of  the  Chemical  Analysis  of  Rocks 8vo,  2  oo 

*  Weaver's  Military  Explosives Svo,  3  oo 

Wells's  Laboratory  Guide  in  Qualitative  Chemical  Analysis Svo,  i  50 

Short  Course  in  Inorganic  Qualitative  Chemical  Analysis  for  Engineering 

Students i2mo,  i  50 

Text-book  of  Chemical  Arithmetic i2mo,  i  25 

Whipple's  Microscopy  of  Drinking-water Svo,  3  50 

Wilson's  Chlorination  Process I2mo,  i  53 

Cyanide  Processes i2mo,  i  50 

Winton's  Microscopy  of  Vegetable  Foods Svo,  7  50 

CIVIL  ENGINEERING. 

BRIDGES  AND  ROOFS.     HYDRAULICS.     MATERIALS   OF    ENGINEER- 
ING.    RAILWAY   ENGINEERING. 

Baker's  Engineers*  Surveying  Instruments 12010,  3  oo 

Bixby's  Graphical  Computing  Table Paper  19^X24!  inches.  25 

Breed  and  Hosmer's  Principles  and  Practice  or  Surveying.     2  Volumes. 

Vol.  I.     Elementary  Surveying Svo,  3  oo 

Vol.  II.     Higher  Surveying Svo,  2  50 

*  Burr's  Ancient  and  Modern  Engineering  and  the  Isthmian  Canal   ....     Svo,  3  50 
Comstock's  Field  Astronomy  for  Engineers Svo,  2  50 

*  Corthell's  Allowable  Pressures  on  Deep  Foundations i2mo,  i   25 

Crandall's  Text-book  on  Geodesy  and  Least  Squares Svo,  3  oo 

Davis's  Elevation  and  Stadia  Tables Svo,  i  oo 

Elliott's  Engineering  for  Land  Drainage i2mo,  i  50 

Practical  Farm  Drainage lamo,  i  oo 

*Fiebeger's  Treatise  on  Civil  Engineering Svo,  5  oo 

Flemer's  Phototopographic  Methods  and  Instruments Svo,  5  oo 

Folwell's  Sewerage.     (Designing  and  Maintenance.) Svo,  3  oo 

Freitag's  Architectural  Engineering Svo,  3  50 

French  and  Ives's  Stereotomy Svo,  2  50 

Goodhue's  Municipal  Improvements I2mo,  i  50 

Gore's  Elements  of  Geodesy Svo,  2  50 

*  Hauch's  and  Rice's  Tables  of  Quantities  for  Preliminary  Estimates  .  .izmo,  i  25 

6 


Hayford's  Text-book  of  Geodetic  Astronomy 8vo,  3  oo 

Bering's  Ready  Reference  Tables.     (Conversion  Factors) i6mo,  mor.  2  50 

Howe's  Retaining  Walls  for  Earth I2mo,  i  25 

*  Ives's  Adjustments  of  the  Engineer's  Transit  and  Level v . . .  i6mo,  Bds.  25 

Ives  and  Hilts's  Problems  in  Surveying i6mo,  mor.  i  50 

Johnson's  (J.  B.)  Theory  and  Practice  of  Surveying Small  8vo,  4  oo 

Johnson's  (L.  J.)  Statics  by  Algebraic  and  Graphic  Methods 8vo,  2  oo 

Kinnicutt,  Winslow  and  Pratt's  Purification  of  Sewage.     (In  Preparation.) 
Laplace's    Philosophical   Essay    on    Probabilities.       (Truscott    and   Emory) 

I2mo,  2    OO 

Mahan's  Descriptive  Geometry 8vo,  i  50 

Treatise  on  Civil  Engineering.     (1873.)     (Wood) 8vo,  5  oo 

Merriman's  Elements  of  Precise  Surveying  and  Geodesy 8vo,  2  50 

Merriman  and  Brooks's  Handbook  for  Surveyors i6mo,  mor.  2  oo 

Nugent's  Plane  Surveying 8vo,  3  50 

Ogden's  Sewer  Construction 8vo,  3  oo 

Sewer  Design i2mo,  2  oo 

Parsons's  Disposal  of  Municipal  Refuse 8vo,  2  oo 

Patton's  Treatise  on  Civil  Engineering 8vo,  half  leather,  7  50 

Reed's  Topographical  Drawing  and  Sketching      4to,  5  oo 

Rideal's  Sewage  and  the  Bacterial  Purification  of  Sewage 8vo,  4  oo 

Riemer's  Shaft-sinking  under  Difficult  Conditions.     (Corning  and  Peele). .  .8vo,  3  oo 

Siebert  and  Biggin's  Modern  Stone-cutting  and  Masonry 8vo,  i  50 

Smith's  Manual  of  Topographical  Drawing.     (McMillan) 8vo,  2  50 

Soper's  Air  and  Ventilation  of  Subways Large  i2mo,  2  50 

Tracy's  Plane  Surveying i6mo,  mor.  3  oo 

'*  Trautwine's  Civil  Engineer's  Pocket-book i6mo,  mor.  5  oo 

Venable's  Garbage  Crematories  in  America 8vo,  2  oo 

Methods  and  Devices  for  Bacterial  Treatment  of  Sewage 8vo,  3  oo 

Wait's  Engineering  and  Architectural  Jurisprudence 8vo,  6  oo 

Sheep,  6  50 

Law  of  Contracts 8vo,  3  oo 

Law  of  Operations  Preliminary  to  Construction  in  Engineering  and  Archi- 
tecture  8vo,  5  oo 

Sheep,  5  50 

Warren's  Stereotomy — Problems  in  Stone-cutting 8vo,  2  50 

*  Waterbury's  Vest-Pocket  Hand-book   of    Mathematics   for   Engineers. 

ajXsl  inches,  mor.  i  oo 
Wtbb's  Problems  in  the  Use  and  Adjustment  of  Engineering  Instruments. 

i6mo,  mor.  i  25 

Wilson's  (H.  N.)  Topographic  Surveying 8vo,  3  50 

Wilson's  (W.  L.)  Elements  of  Railroad  Track  and  Construction i2mo,  2  oo 

BRIDGES  AND  ROOFS. 

Boiler's  Practical  Treatise  on  the  Construction  of  Iron  Highway  Bridges.  .8vo,  2  oo 

Burr  and  Falk's  Design  and  Construction  of  Metallic  Bridges 8vc.  5  oo 

Influence  Lines  for  Bridge  and  Roof  Computations 8vo,  3  oo 

Du  Bois's  Mechanics  of  Engineering.     VoL  II Sirall  4to,  10  oo 

Foster's  Treatise  on  Wooden  Trestle  Bridges 4to,  5  oo 

Fowler's  Ordinary  Foundations 8vo,  3  50 

French  and  Ives's  Stereotomy   ....    8vo,  2  50 

Greene's  Arches  in  Wood,  Iron,  and  Stone 8vo,  2  50 

Bridge  Trusses 8vo,  2  50 

Roof  Trusses 8vo,  i  25 

Grimm's  Secondary  Stresses  in  Bridge  Trusses 8vo,  2  *o 

Heller's  Stresses  in  Structures  and  the  Accompanying  Deformations 8vo,  3  oo 

Howe's  Design  of  Simple  Roof-trusses  in  Wood  and  Steel 8vo,  2  oo 

Symmetrical  Masonry  Arches 8vo,  2  50 

Treatise  on  Arches. 8vo,  4  oo 


Johnson,  Bryan,  and  Turneaure's  Theory  and  Practice  in  the  Designing  of 

Modern  Framed  Structures Small  4to,  10  oo 

Merriraan  and  Jacoby's  Text-book  on  Roofs  and  Bridges: 

Part  I.     Stresses  in  Simple  Trusses 8vo,  2  50 

Part  II.    Graphic  Statics 8vo,    2  50 

Part  III.  Bridge  Design 8vo ,  2  50 

Part  IV.   Higher  Structures 8vo,  2  50 

Morison's  Memphis  Bridge Oblong  4to,  10  oo 

Sondericker's  Graphic  Statics,  with  Applications  to  Trusses,  Beams,  and  Arches. 

8vo,  2  oo 

WaddelTs  De  Pontibus,  Pocket-book  for  Bridge  Engineers i6mo.  mor,  2  oo 

*  Specifications  for  Steel  Bridges I2mo,  50 

Waddell  and  Harrington's  Bridge  Engineering.     (In  Preparation.) 

Wright's  Designing  of  Draw-spans.     Two  parts  in  one  volume 8vo,  3  50 

HYDRAULICS. 

Barnes's  Ice  Formation 8vo,  3  oo 

Bazin's  Experiments  upon  the  Contraction  of  the  Liquid  Vein  Issuing  from 

an  Orifice.     (Trautwine) 8vo,  2  oo 

Bovey's  Treatise  on  Hydraulics 8vo,  5  oo 

Church's  Diagrams  of  Mean  Velocity  of  Water  in  Open  Channels. 

Oblong  4to.  paper,  i  50 

Hydraulic  Motors * 8vo,  2  oo 

Mechanics  of  Engineering 8vo,  6  oo 

Coffin's  Graphical  Solution  of  Hydraulic  Problems i6mo,  mor.  2  50 

Flather's  Dynamometers,  and  the  Measurement  of  Power i2mo,  3  oo 

Folwell's  Water-supply  Engineering 8vo,  4  oo 

Frizell's  Water-power 8vo,  5  oo 

Fuertes's  Water  and  Public  Health I2mo,  i  50 

Water-filtration  Works i2mo,  2  50 

Ganguillet  and  Kutter's  General  Formula  for  the  Uniform  Flow  of  Water  in 

Rivers  and  Other  Channels.     (Bering  and  Trautwine j 8vo,  4  oo 

Hazen's  Clean  Water  and  How  to  Get  It Large  ismo,  i  50 

Filtration  of  Public  Water-supplies 8vo,  3  oo 

Hazlehurst's  Towers  and  Tanks  for  Water-works 8vo,  2  50 

Herschel's  115  Experiments  on  the  Carrying  Capacity  of  Large,  Riveted,  Metal 

Conduits 8vo,  2  oo 

Hoyt  and  Grover's  River  Discharge.. 8vo,  2  oo 

Hubbard  and  Kiersted's  Water- works  Management  and  Maintenance 8vo,  4  oo 

*  Lyndon's  Development  and  Electrical  Distribution  of  Water  Power.  . .  .8vo,  3  oo 
Mason's  Water-supply.     (Considered  Principally  from  a  Sanitary  Standpoint.) 

8vo,  4  oo 

Merriman's  Treatise  on  Hydraulics 8vo,  5  oo 

*  Michie's  Elements  of  Analytical  Mechanics 8vo.  4  oo 

*  Molitor's  Hydraulics  of  Rivers.  Weirs  and  Sluices 8vo,  2  oo 

Richards's  Laboratory  Notes  on  Industrial  Water  Analysis.     (In  Press). 
Schuyler's   Reservoirs  for  Irrigation,   Water-power,   and   Domestic   Water- 
supply.  ...                                   Large  8vo,  5  oo 

*  Thoma-  and  Watt's  Improvement  of  Rivers 4to,  6  oo 

Turneaure  and  Russell's  Public  Water-supplies 8vo.  5  oo 

Wegmann's  Design  and  Construction  of  Dams.     5th  Ed.,  enlarged    4to,  6  oo 

Water-supply  of  the  City  of  New  York  from  1658  to  1895 4to,  10  oo 

Whipple's  Value  of  Pure  Water Large  I2mo,  i  oo 

Williams  and  Hazen's  Hydraulic  Tables 8vo.  i  50 

Wilson's  Irrigation  Engineering Small  8vo,  4  oo 

Wolff's  Windmill  as  a  Prime  Mover 8vo,  3  oo 

Wood's  Elements  of  Analytical  Mechanics 8vo,  3  oo 

Turbines. 8vo,  2  50 

8 


MATERIALS  OF  ENGINEERING. 


Baker's  Roads  and  Pavements 8vo,  5  oo 

Treatise  on  Masonry  Construction 8vo,  5  oo 

Birkmire's  Architectural  Iron  and  SteeL 8vo,  3  50 

Compound  Riveted  Girders  as  Applied  in  Buildings 8vo,  2  oo 

Black's  United  States  Public  Works Oblong  4to.  5  oo 

Bleininger's  Manufacture  of  Hydraulic  Cement.     (In  Preparation.) 

*  Bovey's  Strength  of  Materials  and  Theory  of  Structures 8vo,  7  50 

Burr's  Elasticity  and  Resistance  of  the  Materials  of  Engineering 8vo,  7  50 

Byrne's  Highway  Construction 8vo,  5  oo 

Inspection  of  the  Materials  and  Workmanship  Employed  in  Construction. 

i6mo,  3  oo 

Church's  Mechanics  of  Engineering 8vo.  6  oo 

Du  Bois's  Mechanics  of  Engineering. 

Vol.   I.  Kinematics,  Statics,  Kinetics Small  4to,  7  50 

Vol.  II.  The  Stresses  in  Framed  Structures,  Strength  of  Materials  and 

Theory  of  Flexures. Small  4to,  10  oo 

*Eckel's  Cements,  Limes,  and  Plasters 8vo,  6  oo 

Stone  and  Clay  Products  used  in  Engineering.     (In  Preparation.) 

Fowler's  Ordinary  Foundations 8vo,  3  50 

Graves's  Forest  Mensuration 8vo,  4  oo 

Green's  Principles  of  American  Forestry i2mo,  i  50 

*  Greene's  Structural  Mechanics 8vo,  2  50 

Holly  and  Ladd's  Analysis  of  Mixed  Paints,  Color  Pigments  and  Varnishes 

Large  12010,  2  50 
Johnson's  (C.  M.)  Chemical  Analysis  of  Special  Steels.     (In  Preparation.) 

Johnson's  (J.  B.)  Materials  of  Construction Large  8vo,  6  oo 

Keep's  Cast  Iron 8vo,  2  50 

Kidder's  Architects  and  Builders'  Pocket-book i6mo,  5  oo 

Lanza's  Applied  Mechanics 8vo,  7  50 

Maire's  Modern  Pigments  and  their  Vehicles     . i2mo,  2  oo 

Martens's  Handbook  on  Testing  Materials.     (Henning)     2  vols 8vo,  7  50 

Meurer's  Technical  Mechanics 8vo,  4  oo 

Merrill's  Stones  for  Building  and  Decoration 8vo,  5  oo 

Merriman's  Mechanics  of  Materials 8vo,  5  oo 

*  Strength  of  Materials izmo,  i  oo 

Metcalf's  Steel.     A  Manual  for  Steel-users.     I2mo,  2  oo 

Morrison's  Highway  Engineering 8vo,  2  50 

Patton's  Practical  Treatise  on  Foundations 8vo,  5  oo 

Rice's  Concrete  Block  Manufacture 8vo,  2  oo 

Richardson's  Modern  Asphalt  Pavements 8vo,  3  oo 

Richey's  Handbook  for  Superintendents  of  Construction i6mo,  mor.  4  oo 

*  Ries's  Clays:  Their  Occurrence,  Properties,  and  Uses 8vo,  5  oo 

Sabin's  Industrial  and  Artistic  Technology  of  Paints  ard  Varnish 8vo,  3  oo 

*Schwarz'sLon^leafP5nein  Virgin  Forest "mo,  125 

Snow's  Principal  Species  of  Wood 8vo,  3  50 

Spalding's  Hydraulic  Cement "mo,  2  oo 

Text-book  on  Roads  and  Pavements I2mo,  2  oo 

Taylor  and  Thompson's  Treatise  on  Concrete,  Plain  and  Reinforced 8vo,  5  oo 

Thurston's  Materials  of  Engineering.     In  Three  Parts 8vo,  8  oo 

Part  I.     Non-metallic  Materials  of  Engineering  and  Metallurgy 8vo,  2  oo 

Partn.     Iron  and  Steel 8v<>.  3  5O 

Part  III.     A  Treatise  on  Brasses,  Bronzes,  and  Other  Alloys  and  their 

Constituents 8vo«  2  SO 

Tillson's  Street  Pavements  and  Paving  Materials 8vo,  4  oo 

Turneaure  and  Maurer's  Principles  of  Reinforced  Concrete  Construction..  .8vo,  3  oo 

Waterbury's  Cement  Laboratory  Manual 12010,  i  oo 

0 


RAILWAY  ENGINEERING. 

Andrews's  Handbook  for  Street  Railway  Engineers 3x5  inches,  mor.  i  25 

Berg's  Buildings  and  Structures  of  American  Railroads 4to,  5  oo 

Brooks's  Handbook  of  Street  Railroad  Location i6mo,  mor. 

Butt's  Civil  Engineer's  Field-book i6mo,  mor. 

Crandall's  Railway  and  Other  Earthwork  Tables .  8vo, 

Transition  Curve i6mo,  mor. 

*  Crockett's  Methods  for  Earthwork  Computations 8vo, 

Dawson's  "Engineering"  and  Electric  Traction  Pocket-book i6mo.  mor.  5  oo 

Dredge's  History  of  the  Pennsylvania  Railroad:   (1879) Paper,  5  oo 

Fisher's  Table  of  Cubic  Yards Cardboard,  25 

Godwin's  Railroad  Engineers'  Field-book  and  Explorers'  Guide.  .  .  i6mo,  mor.  2  50 
Hudson's  Tables  for  Calculating  the  Cubic  Contents  of  Excavations  and  Em- 
bankment*  8vo,  I  oo 

Ives   and  Hilts'c   Problems   in  Surveying,  Railroad   Surveying  and   Geodesy 

i6mo,  mor.  i  50 

Molitor  and  Beard's  Manual  for  Resident  Engineers i6mo,  i  oo 

Nagle's  Field  Manual  for  Railroad  Engineers i6mo,  mor.  3  oo 

Philbrick's  Field  Manual  for  Engineers i6mo,  mor.  3  oo 

Raymond's  Railroad  Engineering.     3  volumes. 

Vol.      I.  Railroad  Field  Geometry.     (In  Preparation.) 

Vol.    II.  Elements  of  Railroad  Engineering 8vo,  3  50 

Vol.  III.  Railroad  Engineer's  Field  Book.     (In  Preparation.) 

Searles's  Field  Engineering i6mo,  mor.  3  oo 

Railroad  Spiral i6mo,  mor.  i  50 

Taylor's  Prismoidal  Formulae  and  Earthwork 8vo,  i  50 

*Trautwine's  Fie'd  Practice  of  Laying   Out  Circular  Curves   for  Railroads. 

1 2 mo.  mor,  2  50 

*  Method  of  Calculating  the  Cubic  Contents  of  Excavations  and  Embank- 

ments by  the  Aid  of  Diagrams 8vo,  2  oo 

Webb's  Economics  of  Railroad  Construction Large  i2mo,  2  50 

Railroad  Construction r6mo,  mor.  5  oo 

Wellington's  Economic  Theory  of  the  Location  of  Railways Small  8vo,  5  oo 

DRAWING. 

Barr's  Kinematics  of  Machinery 8vo,  2  50 

*  Bartlett's  Mechanical  Drawing 8vo,  3  oo 

*  "                    "               "             Abridged  Ed 8vo,  150 

Coolidge's  Manual  of  Drawing 8vo,  paper,  i  oo 

Coolidge  and  Freeman's  Elements  of  General  Drafting  for  Mechanical  Engi- 
neers  Oblong  4:0,  2  50 

Durley's  Kinematics  of  Machines 8vo,  4  oo 

Emch's  Introduction  to  Projective  Geometry  and  its  Applications 8vo,  2  50 

Hill's  Text-book  on  Shades  and  Shadows,  and  Perspective 8vo,  2  oo 

Jamison's  Advanced  Mechanical  Drawing 8vo,  2  oo 

Elements  of  Mechanical  Drawing 8vo,  2  50 

Jones's  Machine  Design: 

Part  I.     Kinematics  of  Machinery 8vo,  i  50 

Part  n.    Form,  Strength,  and  Proportions  of  Parts 8vo,  3  oo 

MacCord's  Elements  of  Descriptive  Geometry 8vo,  3  o« 

Kinematics;  or,  Practical  Mechanism 8vo,  5  oo 

Mechanical  Drawing 4to,  4  oo 

Velocity  Diagrams 8vo,  i  50 

McLeod's  Descriptive  Geometry Large  i2mo,  i  50 

*  Mahan's  Descriptive  Geometry  and  Stone-cutting 8vo,  i  50 

Industrial  Drawing.     (Thompson.) 8vo,  3  50 

10 


McLeod's  Descriptive  Geometry Large  i2mo,  i  50 

*  Mahan's  Descriptive  Geometry  and  Stone-cutting 8vo,  i  so 

Industrial  Drawing.  (Thompson ) "... ...... 8vo,  3  50 

Moyer's  Descriptive  Geometry  for  Students  of  Engineering 8vo,  2  oo 

Reed's  Topographical  Drawing  and  Sketching 4to,  5  oo 

Reid's  Course  in  Mechanical  Drawing 8vo,  2  oo 

Text-book  of  Mechanical  Drawing  and  Elementary  Machine  Design. 8vo,  3  oo 

Robinson's  Principles  of  Mechanism 8vo,  3  oo 

Schwamb  and  Merrill's  Elements  of  Mechanism 8vo.  3  oo 

Smith's  (R.  S.)  Manual  of  Topographical  Drawing.  (McMillan) 8vo,  2  50 

Smith  (A.  W.)  and  Marx's  Machine  Design 8vo,  3  oo 

*  Titsworth's  Elements  of  Mechanical  Drawing Oblong  8vo,  i  25 

Warren's  Drafting  Instruments  and  Operations i2mo,  i  25 

Elements  of  Descriptive  Geometry,  Shadows,  and  Perspective 8vo,  3  50 

Elements  of  Machine  Construction  and  Drawing 8vo,  7  50 

Elements  of  Plane  and  Solid  Free-hand  Geometrical  Drawing i2mo,  i  oo 

General  Problems  of  Shades  and  Shadows 8vo,  3  oo 

Manual  of  Elementary  Problems  in  the  Linear  Perspective  of  Form  and 

Shadow i2mo,  i  oo 

Manual  of  Elementary  Projection  Drawing I2mo.  i  50 

Plane  Problems  in  Elementary  Geometry   I2mo,  i  25 

Problems,  Theorems,  and  Examples  in  Descriptive  Geometry 8vo,  2  50 

Weisbach's    Kinematics    and    Power    of    Transmission.        (Hermann    and 

Klein) 8vo,  5  oo 

Wilson's  (H.  M.)  Topographic  Surveying 8vo,  3  50 

Wilson's  (V.  T.)  Free-hand  Lettering 8vo,  i  oo 

Free-hand  Perspective 8vo,  2  50 

Woolf 's  Elementary  Course  in  Descriptive  Geometry*. Large  8vo.  3  oo 

ELECTRICITY  AND  PHYSICS. 

*  Abegg's  Theory  of  Electrolytic  Dissociation,     (von  Ende).  . . i2mo.  i   25 

Andrews's  Hand-Book  for  Street  Railway  Engineering 3X5  inches,  mor.  i  25 

Anthony  and  Brackett's  Text-book  of  Physics.     (Magie) Large  i2mo,  3  oo 

Anthony's  Theory  of  Electrical  Measurements.     (Ball) i2mo,  i  oo 

Benjamin's  History  of  Electricity 8vo,  3  oo 

Voltaic  Cell.  . 8vo,  3  oo 

Betts's  Lead  Refining  and  Electrolysis 8vo,  4  oo 

Classen's  Quantitative  Chemical  Analysis  by  Electrolysis.     (Boltwood).  .8vo,  3  oo 

*  Collins's  Manual  of  Wireless  Telegraphy I2mo,  i  50 

Mor.  2  oo 

Crehore  and  Squier's  Polarizing  Photo-chronograph 8vo,  3  oo 

*  Danneel's  Electrochemistry.     (Merriam) i2mo,  i  25 

Dawson's  "Engineering"  and  Electric  Traction  Pocket-book  .  .  .  .i6mo,  mor.  5  oo 
Dolezalek's  Theory  of  the  Lead  Accumulator  (Storage  Battery),     (von  Ende) 

I2mo,  2  50 

Duhem's  Thermodynamics  and  Chemistry.     (Burgess) 8vo,  4  oo 

Flather's  Dynamometers,  and  the  Measurement  of  Power i2mo,  3  oo 

Gilbert's  De  Magnete.     (Mottelay) 8vo,  2  50 

*  Hanchett's  Alternating  Currents i2mo,  i  oo 

Bering's  Ready  Reference  Tables  (Conversion  Factors)   i6mo,  mor.  2  50 

*  Hobart  and  Ellis's  High-speed  Dynamo  Electric  Machinery 8vo,  6  oo 

Holman's  Precision  of  Measurements 8vo,  2  oo 

Telescopic   Mirror-scale  Method,  Adjustments,  and   Tests ....  Large  8vc ,  75 

*  Karapetoff's  Experimental  Electrical  Engineering 8vo,  6  oo 

Kinzbrunner's  Testing  of  Continuous-current  Machines. 8vo,  2  oo 

Landauer's  Spectrum  Analysis.     (Tingle) 8vo,  3  oo 

Le  Chatelier's  High-temperature  Measurements.  (Boudouard— Burgess)..  i2mo,  3  oo 

Lob's  Electrochemistry  of  Organic  Compounds.     (Lorenz) .  .   8vo,  j  oo 

*  London's  Development  and  Electrical  Distribution  of  Water  Power 8vo,  3  oo 

11 


*  Lyons's  Treatise  on  Electromagnetic  Phenomena.  Vols.  I.  and  II.  8vo,  each  6  oo 

*  Michie's  Elements  of  V/ave  Motion  Relating  to  Sound  and  Light 8vo,  4  oo 

Morgan's  Outline  of  the  Theory  of  Solution  and  its  Results i2mo,  i   oo 

*  Physical  Chemistry  for  Electrical  Engineers i2mo,  i   50 

Niaudet's  Elementary  Treatise  on  Electric  Batteries.     (Fishback) izmo,  2   50 

*  Norris's  Introduction  to  the  Study  of  Electrical  Engineering 8vo,  2   50 

*  Parshall  and  Hobart's  Electric  Machine  Design 4to,  half  mor.  12   50 

Reagan's  Locomotives:   Simple,   Compound,   and   Electric.     New  Edition. 

Large  12  mo,  3   50 

*  Rosenberg's  Electrical  Engineering.    (HaldaneGee  —  Kinzbrunner)  .  .  .8vo,  2  oo 

Ryan,  Norris,  and  Hozie's  Electrical  Machinery.     Vol.  I 8vo,  2   50 

Schapper's  Laboratory  Guide  for  Students  in  Physical  Chemistry I2mo,  i   oo 

*  Tillman's  Elementary  Lessons  in  Heat 8vo,  i   50 

Tory  and  Pitcher's  Manual  of  Laboratory  Physics Large  i2mo,  2   oo 

Ulke's  Modern  Electrolytic  Copper  Refining 8vo,  3  oo 

LAW. 

Brennan's  Handbook:    A    Compendium    of    Useful    Legal    Information    for 

Business  Men i6mo,  mor.  5  oo 

*  Davis's  Elements  of  Law 8vo,  2  50 

*  Treatise  on  the  Military  Law  of  United  States 8vo,  7  oo 

Sheep,  7  50 

*  Dudley's  Military  Law  and  the  Procedure  of  Courts-martial .  .  .Large  i2mo,  2  50 

Manual  for  Courts-martial i6mo,  mor.  i   50 

Wait's  Engineering  and  Architectural  Jurisprudence 8vo,  6  oo 

Sheep,  6  50 

Law  of  Contracts 8vo,  3  oo 

Law  of  Operations  Preliminary  to  Construction  in  Engineering  and  Archi- 
tecture   8  vo,  5  oo 

Sheep,  5  50 
MATHEMATICS. 

Baker's  Elliptic  Functions 8vo,  50 

Briggs's  Elements  of  Plane  Analytic  Geometry.     (Bocher) i2mo,  oo 

*  Buchanan's  Plane  and  Spherical  Trigonometry 8vo,  oo 

Byerley's  Harmonic  Functions 8vo,  oo 

Chandler's  Elements  of  the  Infinitesimal  Calculus 12  mo,  oo 

Coffin's  Vector  Analysis.     (In  Press.) 

Compton's  Manual  of  Logarithmic  Computations i2mo,  50 

*  Dickson's  College  Algebra Large  i2mo,  50 

*  Introduction  to  the  Theory  of  Algebraic  Equations Large  12  mo,  25 

Emch's  Introduction  to  Projective  Geometry  and  its  Applications 8vo,  50 

Fiske's  Functions  of  a  Complex  Variable 8vo,  co 

Halsted's  Elementary  Synthetic  Geometry 8vo,  50 

Elements  of  Geometry 8vo,  75 

*  Rational  Geometry i2mo,  50 

Hyde's  Grassmann's  Space  Analysis 8vo,  oo 

*  Johnson's  (J.  B.)  Three-place  Logarithmic  Tables:  Vest-pocket  size,  paper,  15 

100  copies,  5  oo 

Mounted  on  heavy  cardboard,  8  X   10  inches,  25 

10  copies,  a   oo 
Johnson's  (W.  W.)  Abridged  Editions  of  Differential  and  Integral  Calculus 

Large  12010,  i  vol.  2  50 

Curve  Tracing  in  Cartesian  Co-ordinates                     12  mo,  i  oo 

Differential  Equations                                           8vo,  i   oo 

Elementary  Treatise  on  Differential  Calculus                         Large  12100,  i   50 

Elementary  Treatise  on  the  Integral  Calculus                       Large  12  mo,  i   50 

Theoretical  Mechanics i2mo,  3  oo 

Theory  of  Errors  and  the  Method  of  Least  Squares                          12  mo,  i   50 

Treatise  on  Differential  Calculus                                              Large  12  mo,  3  oo 
12 


Johnson's  Treatise  on  the  Integral  Calculus Large  i2mo,    3  oo 

Treatise  on  Ordinary  and  Partial  Differential  Equations.  Large  i2mo,    3  50 
Karapetoff's  Engineering  Applications  of  Higher  Mathematics.      (In   Pre- 
paration.) 
Laplace's  Philosophical  Essay  on  Probabilities.     (Truscott  and  Emory). .i2mo,     2  oo 

*  Ludlow  and  Bass's  Elements  of  Trigonometry  and  Logarithmic  and  Other 

Tables 8vo,     j  oo 

Trigonometry  and  Tables  published  separately Each,     2  oo 

*  Ludlow's  Logarithmic  and  Trigonometric  Tables 8vo,     i  oo 

Macfarlane's  Vector  Analysis  and  Quaternions 8vo,     i  oo 

McManon's  Hyperbolic  Functions 8vo,     i  oo 

Manning's  Irrational  Numbers  and  their  Representation  by  Sequences  and 

Series i2mo,     i   25 

Mathematical  Monographs.     Edited  by  Mansfield  Merriman  and  Robert 

S.  Woodward Octavo,  each     i  oo 

No.  i.  History  of  Modern  Mathematics,  by  David  Eugene  Smith. 
No.  2.  Synthetic  Projective  Geometry,  by  George  Bruce  Halsted. 
No.  3.  Determinants,  by  Laenas  Gifford  Weld.  No.  4.  Hyper- 
bolic Functions,  by  James  McMahon.  No.  S-  Harmonic  Func- 
tions, by  William  E.  Byerly.  No.  6.  Grassmann's  Space  Analysis, 
by  Edward  W.  Hyde.  No.  7.  Probability  and  Theory  of  Errors, 
ty  Robert  S.  Woodward.  No.  8.  Vector  Analysis  and  Quaternions, 
by  Alexander  Macfarlane.  No.  9.  Differential  Equations,  by 
William  Woolsey  Johnson.  No.  10.  The  Solution  of  Equations, 
by  Mansfield  Merriman.  No.  u.  Functions  of  a  Complex  Variable, 
by  Thomas  S.  Fiske. 

Maurer's  Technical  Mechanics 8vo,    4  oo 

Merriman's  Mefhofl  of  Least  Squares 8vo,    2  oo 

Solution  of  Equations 8vo,     I  oo 

Rice  and  Johnson's  Differential  and  Integral  Calculus.     2  vols.  in  one. 

I^arge  i2mo,     i  50 

Elementary  Treatise  on  the  Differential  Calculus Large  I2mo,     3  oo 

Smith's  History  of  Modern  Mathematics 8vo,     i  oo 

*  Veblen  and  Lennes's  Introduction  to  the  Real  Infinitesimal  Analysis  of  One 

Variable 8vo,     2  oo 

*  Waterbury's  Vest  Pocket  Hand-Book  of  Mathematics  for  Engine' rs. 

aJXsl  inches,  mor.     i  oo 

Weld's  Determinations 8vo,     i  co 

Wood's  Elements  of  Co-ordinate  Geometry 8vo,    2  oo 

Woodward's  Probability  aid  Theory  of  Errors 8vo,     I  oo 

MECHANICAL  ENGINEERING. 

MATERIALS  OF   ENGINEERING,  STEAM-ENGINES  AND  BOILERS. 

Bacon's  forge  Practice I2mo,  i   50 

Baldwin's  Steam  Heating  for  Buildings I2mo,  2  50 

Bair's  Kinematics  of  Machinery 8vo,  2  50 

*  Bartlett's  Mechanical  Drawing 8vo,  3  oo 

*  "  "  "        Abridged  Ed 8vo,    150 

Benjamin's  Wrinkles  and  Recipes i2mo,    2  oo 

*  Burr's  Ar  cient  and  Modern  Engineering  and  the  Isthmian  Canal 8vo,    3  50 

Carpenter's  Experimental  Engineering 8vo,    6  oo 

Heating  and  Ventilating  Buildings 8vo,  4  oo 

Clerk's  Gas  and  Oil  Engine Large  i2mo,  4  oo 

Compton's  First  Lessons  in  Metal  Working I2mo,  i  50 

Compton  and  De  Groodt's  Speed  Lathe i2mo,  i  50 

Coolidge's  Manual  of  Drawing 8vo,  paper,  i  oo 

Coolidge  and  Freeman's  Elements  of  General  Drafting  for  Mechanical  En- 
gineers  Oblong  410,  2  50 

13 


50 

00 
00 
00 
25 
00 


Cromwell's  Treatise  on  Belts  and  Pulleys izmo,  i  50 

Treatise  on  Toothed  Gearing I2mo, 

Durley's  Kinematics  of  Machines 8vo, 

Flather's  Dynamometers  and  the  Measurement  of  Power izmo, 

Rope  Driving I2mo, 

Gill's  Gas  and  Fuel  Analysis  for  Engineers I2mo, 

Goss  s  Locomotive  Sparks 8vo, 

Greene's  Pumping  Machinery.     (In  Preparation.) 

Bering's  Ready  Reference  Tables  (Conversion  Factors) i6mo,  mor.  2  50 

*  Hobart  and  Ellis's  High  Speed  Dynamo  Electric  Machinery 8vo,  6  oo 

Button's  Gas  Engine 8vof  5  oo 

Jamison's  Advanced  Mechanical  Drawing 8vo,  2  oo 

Elements  of  Mechanical  Drawing 8vo,  2  50 

Jones's  Gas  Engine.     (In  Press.) 
Machine  Design: 

Part  I.     Kinematics  of  Machinery 8vo,  i  50 

Part  II.     Form,  Strength,  and  Proportions  of  Parts 8vo,  3  oo 

Kent's  Mechanical  Engineers'  Pocket-book i6mo,  mor.  5  oo 

Kerr's  Power  and  Power  Transmission 8vo,  2  oo 

Leonard's  Machine  Shop  Tools  and  Methods 8vo,  4  oo 

*  Lorenz's  Modern  Refrigerating  Machinery.    (Pope,  Haven,  and  Dean) . .  .  8vo,  4  oo 
MacCord's  Kinematics;   or,  Practical  Mechanism 8vo,  5  oo 

Mechanical  Drawing 4to,  4  oo 

Velocity  Diagrams 8vo,  i  50 

MacFarland's  Standard  Reduction  Factors  for  Gases 8vo,  i   50 

Mahan's  Industrial  Drawing.     (Thompson) 8vo,  3  50 

Oberg's   Screw  Thread  Systems,   Taps,    Dies,  Cutters,  and   Reamers.      (In 
Press.) 

*  Parshall  and  Hobart's  Electric  Machine  Design Small  4to,  half  leather,  12  50 

Peele's  Compressed  Air  Plant  for  Mines 8vo,  3  oo 

Poole's  Calorific  Power  of  Fuels 8vo,  3  oo 

*  Porter's  Engineering  Reminiscences,  1855  to  1882 8vo,  3  oo 

Reid's  Course  in  Mechanical  Drawing 8vo,  2  oo 

Text-book  of  Mechanical  Drawing  and  Elementary  Machine  Design. 8vo,  3  oo 

Richard's  Compressed  Air i2mo,  i  50 

Robinson's  Principles  of  Mechanism 8vo,  3  oo 

Schwamb  and  Merrill's  Elements  of  Mechanism 8vo,  3  oo 

Smith's  (O.)  Press-working  of  Metals 8vo,  3  oo 

Smith  (A.  W.)  and  Marx's  Machine  Design .  .8vo,  3  oo 

Sorel '  s  Carbureting  and  Combustion  in  Alcohol  Engines .    (Woodward  and  Preston) . 

Large  12 mo,  3  oo 

Thurston's  Animal  as  a  Machine  and  Prime  Motor,  and  the  Laws  of  Energetics. 

12010,  z  oo 

Treatise  on  Friction  and  Lost  Work  in  Machinery  and  Mill  Work...  8vo,  3  oo 

Tillson's  Complete  Automobile  Instructor i6mo,  i  50 

mor.  a  oo 

Titsworth's  Elements  of  Mechanical  Drawing Oblong  8vo,  i   25 

Warren's  Elements  of  Machine  Construction  and  Drawing 8vo,  7  50 

*  Waterbury's  Vest  Pocket  Band  Book  of  Mathematics  for  Engineers. 

2}X5«  inches,  mor.  i   oo 
Weisbach's    Kinematics    and    the    Power   of    Transmission.     (Berrmann — 

Klein) 8vo,  500 

Machinery  of  Transmission  and  Governors.     (Berrmann— Klein)..  .8vo,  5  oo 

Wood's  Turbines 8vo,  2  50 

MATERIALS  OF   ENGINEERING 

*  Bovey's  Strength  of  Materials  and  Theory  of  Structures 8vo,  7  50 

Burr's  Elasticity  and  Resistance  of  the  Materials  of  Engineering 8vo,  7  50 

Church's  Mechanics  of  Engineering 8vo,  6  oo 

*  Greene's  Structural  Mechanics 8vo,  2  50 

14 


Holley  and  Ladd's  Analysis  of  Mixed  Paints,  Color  Pigments,  and  Varnishes. 

Large  i2mo,  2  50 

Johnson's  Materials  of  Construction 8vo,  6  oo 

Keep's  Cast  Iron.    8vo,  2  50 

Lanza's  Applied  Mechanics 8vo,  7  50 

Maire's  Modern  Pigments  and  their  Vehicles I2mo,  2  oo 

Martens's  Handbook  on  Testing  Materials.     (Henning) 8vo,  7  50 

Maurer's  Technical  Mechanics 8vo,  4  oo 

Merriman's  Mechanics  of  Materials 8vo,  5  oo 

*         Strength  of  Materials I2mo,  i  oo 

Metcalf's  Steel.     A  Manual  for  Steel-users i2mo,  2  oo 

Sabin's  Industrial  and  Artistic  Technology  of  Paints  and  Varnish. 8vo,  3  oo 

Smith's  Materials  of  Machines I2mo,  I  oo 

Thurston's  Materials  of  Engineering 3  vols.,  8vo,  8  oo 

Part  I.       Non-metallic  Materials  of  Engineering  and  Metallurgy. .  .8vo,  2  oo 

Part  II.      Iron  and  Steel 8vo,  3  50 

Part  HI.     A  Treatise  on  Brasses,  Bronzes,  and  Other  Alloys  and  their 

Constituents 8vo,  2  50 

Wood's  (De  V.)  Elements  of  Analytical  Mechanics 8vo,  3  oo 

Treatise  on    the    Resistance    of    Materials  and    an  Appendix  on  the 

Preservation  of  Timber 8vo,  a  oo 

Wood's  (M.  P.)  Rustless  Coatings:    Corrosion  and  Electrolysis  of  Iron  and 

Steel 8vo,  4  oo 

STEAM-ENGINES  AND  BOILERS. 

Berry's  Temperature-entropy  Diagram 1 2mo,  i  25 

Carnot's  Reflections  on  the  Motive  Power  of  Heat.     (Thurston) I2mo,  i  50 

Chase's  Art  of  Pattern  Making i2mo,  2  50 

Creighton's  Steam-engine  and  other  Heat-motors 8vo,  500 

Dawson's  "Engineering"  and  Electric  Traction  Pocket-book i6mo,  mor.  5  oo 

Ford's  Boiler  Making  for  Boiler  Makers i8mo,  i  oo 

*Gebhardt's  Steam  Power  Plant  Engineering 8vo,  6  oo 

Goss's  Locomotive  Performance 8vo,  5  oo 

Heraenway's  Indicator  Practice  and  Steam-engine  Economy i2mo,  2  oo 

Button's  Heat  and  Heat-engines 8vo.  5  oo 

Mechanical  Engineering  of  Power  Plants 8vo,  5  oo 

Kent's  Steam  boiler  Economy 8vo,  4  oo 

Kneass's  Practice  and  Theory  of  the  Injector 8vo,  i  50 

MacCord's  Slide-valves 8vo,  2  oo 

Meyer's  Modern  Locomotive  Construction 4to,  10  oo 

Meyer's  Steam  Turbines.     (In  Press.) 

Peabody's  Manual  of  the  Steam-engine  Indicator i2mo.  i  50 

Tables  of  the  Properties  of  Saturated  Steam  and  Other  Vapors 8vo,  i  oo 

Thermodynamics  of  the  Steam-engine  and  Other  Heat-engines 8vo,  5  oo 

Valve-gears  for  Steam-engines 8vo,  2  50 

Peabody  and  Miller's  Steam-boilers 8vo,  4  oo 

Pray's  Twenty  Years  with  the  Indicator Large  8vo,  2  50 

Pupin's  Thermodynamics  of  Reversible  Cycles  in  Gases  and  Saturated  Vapors. 

(Osterberg). i2mo,  i  25 

Reagan's  Locomotives.    Simple,  Compound,  and  Electric.     New  Edition. 

Large  i2mo,  3  50 

Sinclair's  Locomotive  Engine  Running  and  Management i2mo,  2  oo 

Smart's  Handbook  of  Engineering  Laboratory  Practice i2mo,  2  50 

Snow's  Steam-boiler  Practice 8vo,  3  oo 

Spangler's  Notes  on  Thermodynamics i2mo,  i  oo 

Valve-gears 8vo,  2  50 

Spangler,  Greene,  and  Marshall's  Elements  of  Steam-engineering 8vo,  3  oo 

Thomas's  Steam-turbines 8vo,  4  oo 

15 


Thurston's  Handbook  of  Engine  and  Boiler  Trials,  and  the  Use  of  the  Indi- 
cator and  the  Prony  Brake 8vo,  5  oo 

Handy  Tables 8vo,  i  50 

Manual  of  Steam-boilers,  their  resigns,  Construction,  and  Operation..8vo,  5  oo 

Thurston's  Manual  of  the  Steam-engine 2  vols.,  8vo,  10  oo 

Part  I.     History,  Structure,  and  Theory SVD,  6  oo 

Part  II.     Design,  Construction,  and  Operation 8vo,  6  oo 

Steam-boiler  Explosions  in  Theory  and  in  Practice 12 mo,  i  50 

Wehrenfenning's  Analysis  and  Softening  of  Boiler  Feed-water  (Patterson)   8vo,  4  oo 

Weisbach's  Heat,  Steam,  and  Steam-engines.     (Du  Bois) 8vo,  5  oo 

T/hitham's  Steam-engine  Design 8vo,  5  oo 

Wood's  Thermodynamics,  Heat  Motors,  and  Refrigerating  Machines.  .  .8vo,  4  oo 

MECHANICS  PURE  AND  APPLIED. 

Church's  Mechanics  of  Engineering 8vo,  6  oo 

Notes  and  Examples  in  Mechanics 8vo,  2  oo 

Dana's  Text-book  of  Elementary  Mechanics  for  Colleges  and  Schools.  .i2mo,  i  50 
Du  Bois's  Elementary  Principles  of  Mechanics: 

VoL      I.     Kinematics 8vo,  3  50 

VoL    II.     Statics 8vo,  4  oo 

Mechanics  of  Engineering.     Vol.    I Small  4to,  7  50 

VoL  II. Small  4to,  10  oo 

*  Greene's  Structural  Mechanics 8vo,  2  50 

James's  Kinematics  of  a  Point  and  the  Rational  Mechanics  of  a  Particle. 

Large  12 mo,  2  oo 

*  Johnson's  (W.  W.)  Theoretical  Mechanics I2mo.  3  oo 

Lanza's  Applied  Mechanics 8vo,  7  50 

*  Martin's  Text  Book  on  Mechanics,  VoL  I,  Statics i2mo,  i  25 

*  Vol.  2,  Kinematics  and  Kinetics  . .  lamo,  1  50 
Maurer's  Technical  Mechanics 8vo,  4  oo 

*  Merriman's  Elements  of  Mechanics I2mo,  I  oo 

Mechanics  of  Materials 8vo,  5  oo 

*  Michie's  Elements  of  Analytical  Mechanics 8vo,  4  oo 

Robinson's  Principles  of  Mechanism 8vo,  3  oo 

Sanborn's  Mechanics  Problems Large  i2mo,  i  50 

Schwamb  and  Merrill's  Elements  of  Mechanism 8vo,  3  oo 

Wood's  Elements  of  Analytical  Mechanics Cvo,  3  oo 

Principles  of  Elementary  Mechanics i2mo,  i  25 

MEDICAL. 

*  Abderhalden's  Physiological  Chemistry  in  Thirty  Lectures.    (Hall  and  Defren) 

8vo.  5  oo 

von  Behring's  Suppression  of  Tuberculosis.     (Bolduan) i2mo,  i  oo 

*  Bolduan's  Immune  Sera i2mo,  i  50 

Borders  Contribution  to  Immunity.     (Gay).     (In  Preparation.) 

Davenport's  Statistical  Methods  with  Special  Reference  to  Biological  Varia- 
tions  * 6mo,  mor.  i  50 

Ehrlich's  Collected  Studies  on  Immunity.     (Bolduan) 8vo,  6  oo 

*  Fischer's  Physiology  of  Alimentation Large  i2mo,  cloth,  2  oo 

de  Fursac's  Manual  of  Psychiatry.     (Rosanoff  and  Collins) Large  i2mo,  2  50 

Hammarsten's  Text-book  on  Physiological  Chemistry.     (Mandel) 8vo,  4  oo 

Jackson's  Directions  for  Laboratory  Work  in  Physiological  Chemistry.  ..8vo,  i   25 

Lassar-Cohn's  Practical  Urinary  Analys's.     fLorenz) lamo,  i  oo 

Mandel's  Hand  Book  for  the  Bi  -Chemical  Laboratory.  ..                      .  .  12 mo,  i  50 

*  Pauli's  Physical  Chemistry  in  the  Service  of  Medicine.     (Fischer) I2mo,  i  25 

*  Pozzi-Escot's  Toxins  and  Venoms  and  their  Antibodies.     (Cohn) I2mo.  i  oo 

Rostoski's  Serum  Diagnosis.     (Bolduan  \  .                                      izmo,  i  oo 

Ruddiman's  Incompatibilities  in  Prescriptions 8vo.  2  oo 

Whys  in  Pharmacy 12mo-  x  °° 

16 


Salkowski's  Physiological  and  Pathological  Chemistry.     (Orndorff) 8vo,  2  50 

*  Satterlee's  Outlines  of  Human  Embryology .' i2mo  i   25 

Smith's  Lecture  Notes  on  Chemistry  for  Dental  Students 8vo,  2  50 

Steel's  Treatise  on  the  Diseases  of  the  Dog 8vo,  3  50 

*  Whipple's  Typhoid  Fever Large  i2mo,  3  oo 

Woodhull's  Notes  on  Military  Hygiene i6mo,  I  50 

*  Personal  Hygiene . .  i2mo,  I  oo 

Worcester  and  Atkinson's  Small  Hospitals  Establishment  and  Maintenance, 

and  S  ggestions  for  Hospital  Architecture,  with  Plans  for  a  Small 

Hospital i2mo,  i  25 

METALLURGY. 

Betts's  Lead  Refining  by  Electrolysis 8vo,  4  oo 

Holland's  Encyclopedia  of  Founding  and  Dictionary  of  Foundry  Terms  Used 

in  the  Practice  of  Moulding 12 mo,  3  oo 

Iron  Founder 1 2mo,  2  50 

"           "        Supplement 1 2mo,  2  50 

Douglas's  Untechnical  Addresses  on  Technical  Subjects i2mo,  i  oo 

Goesel's  Minerals  and  Metals:  A  Reference  Book    i6mo,  mor.  3  oc 

*  Iles's  Lead-smelting i2mo,  2  50 

Keep's  Cast  Iron 8vo,  2  50 

LeChatelier's High-temperature  Measurements.   (Boudouard — Burgess)  i2mo,  3  oo 

Metcalfs  Steel.     A  Manual  for  Steel-users i2mo,  2  oo 

Miller's  Cyanide  Process i2mo,  i   oo 

Minet's  Production  of  Aluminium  and  its  Industrial  Use.    (Waldo)  .  .  . i2mo,  2  50 

Robine  and  Lenglen's  Cyanide  Industry.     (Le  Clerc) 8vo,  4  oo 

Ruer's  Elements  of  Metallography.      (Mathewson       (In  Press.) 

Smith's  Materials  of  Machines i2mo,  i  oo 

Tate  and  Stone's  Foundry  Practice.     (In  Press.  > 

Thurston's  Materials  of  Engineering.     In  Three  Parts  .     8vo,  8  oo 

Part  I.         Non-metallic  Materials  of  Engineering  and  Metallurgy  .  .  .  8vo,  2  oo 

Part  n.       Iron  and  Steel 8vo,  3  50 

Part  HI.     A  Treatise  on  Brasses,  Bronzes,  and  Other  Alloys  and  their 

Constituents 8vo,  2  50 

Ulke's  Modern  Electrolytic  Copper  Refining 8vo,  3  oo 

West's  American  Foundry  Practice i2mo,  2  50 

Moulder's  Text  Book    12010,  2  50 

Wilson's  Chlorination  Process i2mo,  i   50 

Cyanide  Processes I2mo,  i  50 

MINERALOGY. 

Barfinger's  Description  of  Minerals  of  Commercial  Va'ue Oblong,  mor.  2  50 

Boyd's  Resources  of  Southwest  Virginia 8vo,  3  oo 

Boyd's  Map  of  Southwest  Virginia. Pocket-book  form.  2  oo 

*  Browning's  Introduction  to  the  Rarer  Elements 8vo,  i  50 

Brush's  Manual  of  Determinative  Mineralogy.     (Penfield) 8vo,  4  oo 

Butler's  Pocket  Hand-Book  of  Minerals i6mo,  mor.  3  oo 

Chester's  Catalogue  of  Minerals 8vo,  paper,  i  oo 

Cloth,  i  25 

*  Crane's  Gold  and  Silver 8vo,  5  oo 

Dana's  First  Appendix  to  Dana's  New  "  System  of  Mineralogy. ." .    Large  8vo,  i  oo 

Manual  of  Mineralogy  and  Petrography i2mo  2  oo 

Minerals  and  How  to  Study  Them .  I2mo,  I  50 

System  of  Mineralogy Large  8vo,  half  leather,  12  50 

Text-book  of  Mineralogy 8vo,  4  oo 

Douglas's  Untechnical  Address.es  on  Technical  Subjects i2mo,  i  oo 

Eakle's  Mineral  Tables . .  -8vo,  i  25 

Stone  and  Clay  Products  Used  in  Engineering.     ( In  Preparation. ) 
17 


Egleston's  Catalogue  of  Minerals  and  Synonyms 8vo,  2  50 

Goesel's  Minerals  and  Metals :     A  Reference  Book i6mo  mor.  3  oo 

Groth's  Introduction  to  Chemical  Crystallography  (Marshall) 12 mo,  i  25 

*  Iddings's  Rock  Minerals 8vo,  5  oo 

Johannsen's  Determination  of  Rock-forming  Minerals  in  Thin  Sections 8vo,  4  oo 

*  Martin's  Laboratory  Guide  to  Qualitative  Analysis  with  the  Blowpipe,  istno,  60 
Merrill's  Non-metallic  Minerals:  Their  Occurrence  and  Uses 8vo,  4  oo 

Stones  for  Building  and  Decoration . .  8vo,  5  oo 

*  Penfield's  Notes  on  Determinative  Mineralogy  and  Record  of  Mineral  Tests. 

8vo,  paper,  50 
Tables    of    Minerals,    Including   the  Use  of  Minerals  and  Statistics  of 

Domestic  Production 8vo,  i  oo 

*  Pirsson's  Rocks  and  Rock  Minerals izmo,  2  50 

*  Richards's  Synopsis  of  Mineral  Characters I2mo,  mor.  i  25 

*  Ries's  Clays:  Their  Occurrence,  Properties,  and  Uses 8vo,  5  oo 

*  TiUman's  Text-book  of  Important  Minerals  and  Rocks 8vo,  2  oo 

MINING. 

*  Beard's  Mine  Gases  and  Explosions Large  i2mo,  3  oo 

Boyd's  Map  of  Southwest  Virginia Pocket-book  rorm,  2  oo 

Resources  of  Southwest  Virginia 8vo,  3  oo 

*  Crane's  Gold  and  Silver 8vo,  5  oo 

Douglas's  Untechnical  Addresses  on  Technical  Subjects I2mo  i  oo 

Eissler's  Modern  High  Explosives 8vo,  4  oo 

Goesel's  Minerals  and  Metals :     A  Reference  Book 1 6mo,  mor.  3  oo 

Ir.lseng's  Manual  of  Mining 8vo,  5  oo 

*  Iles's  Lead-smelting I2mo,  2  50 

Miller's  Cyanide  Process i2mo,  i  oo 

O'Driscoll's  Notes  on  the  Treatment  of  Gold  Ores Svo,  2  oo 

Peele's  Compressed  Air  Plant  for  Mines 8vo,  3  oo 

Riemer's  Shaft  Sinking  Under  Difficult  Conditions.     (Corning  and  Peele) ...  Svo,  3  oo 

Robine  and  Lenglen's  Cyanide  Industry.     (Le  Clerc) Svo,  4  oo 

*  Weaver's  Military  Explosives Svo,  3  oo 

Wilson's  Chlorination  Process nmo,  i  50 

Cyanide  Processes i2mo,  i  50 

Hydraulic  and  Placer  Mining.     2d  edition,  rewritten 12010,  2  50 

Treatise  on  Practical  and  Theoretical  Mine  Ventilation 12 mo,  i  25 

SANITARY  SCIENCE. 

Association  of  State  and  National  Food  and  Dairy  Departments,  Hartford  Meeting, 

1906 Svo,  3  oo 

Jamestown  Meeting,  1907 Svo,  3  oo 

*  Bashore's  Outlines  of  Practical  Sanitation I2mo,  I  25 

Sanitation  of  a  Country  House I2mo,  i  co 

Sanitation  of  Recreation  Camps  and  Parks i2mo,  i  oo 

Folwell's  Sewerage.  (Designing,  Construction,  and  Maintenance) Svo,  3  oo 

Water-supply  Engineering Svo,  4  oo 

Fowler's  Sewage  Works  Analyses i2mo,  2  oo 

Fuertes's  Water-filtration  Works I2mo,  2  50 

Water  and  Public  Health i2mo,  i  50 

Gerhard's  Guide  to  Sanitary  House-inspection i6mo,  i  oo 

*  Modern  Baths  and  Bath  Houses Svo,  3  oo 

Sanitation  of  Public  Buildings tamo,  i   50 

Hazen's  Clean  Water  and  How  to  Get  It Large  i2mo,  i  50 

Filtration  of  Public  Water-supplies Svo.  3  oo 

Kinnlcut,  Winslow  and  Pratt's  Purification  of  Sewage.     (In  Press.) 

Leach's   Inspection   and    Analysis  of  Food  with  Special  Reference   to  State 

Control Svo.  7  oo 

18 


Mason's  Examination  of  Water.     (Chemical  and  Bacteriological) I2mo,  125 

Water-supply.  ( Considered  Principally  from  a  Sanitary  Standpoint) . .  8vo,  4  oo 

*  Merriman's  Elements  of  Sanitary  Engineering 8vo,  2  oo 

Ogden's  Sewer  Design I2mo,  2  oo 

Parsons's  Disposal  of  Municipal  Refuse 8vo,  2  oo 

Prescott  and  Winslow's  Elements  of  Water  Bacteriology,  with  Special  Refer- 
ence to  Sanitary  Water  Analysis I2mo,  i  50 

*  Price's  Handbook  on  Sanitation I2mo,  i  50 

Richards's  Cost  of  Cleanness.     A  Twentieth  Century  Problem i2mo,  i  oo 

Cost  of  Food.     A  Study  in  Dietaries i2mo,  i  oo 

Cost  of  Living  as  Modified  by  Sanitary  Science. i2mo,  i  oo 

Cost  of  Shelter.     A  Study  in  Economics i2mo,  I  oo 

*  Richards  and  WilHams's  Dietary  Computer 8vo,  i  50 

Richards  and   Woodman's  Air,   Water,  and  Food  from  a  Sanitary  Stand- 
point  8vo,  2  oo 

Rideal's   Disinfection  and  the  Preservation  of  Food.        8vo,  400 

Sewage  and  Bacterial  Purification  of  Sewage 8vo,  4  oo 

Soper's  Air  and  Ventilation  of  Subways Large  i2mo,  2  50 

Turneaure  and  Russell's  Public  Water-supplies 8vo,  5  oo 

Venable's  Garbage  Crematories  in  America 8vo,  2  oo 

Method  and  Devices  for  Bacterial  Treatment  of  Sewage 8vo,  3  oo 

Ward  and  Whipple's  Freshwater  Biology i2tno,  2  50 

Whipple's  Microscopy  of  Drinking-water 8vo,  3  50 

*  Typhod  Fever Large  i2mo,  3  oo 

Value  of  Pure  Water Large  12010,  i  oo 

Winslow's  Bacterial  Classification 1 2mo,  2  50 

Winton's  Microscopy  of  Vegetable  Foods. 8vo,  7  50 

MISCELLANEOUS. 

Emmons's  Geological  Guide-book  of  the  Rocky  Mountain  Excursion  of  the 

International  Congress  of  Geologists Large  8vo,  i  50 

Ferrel's  Popular  Treatise  on  the  Winds 8vo,  4  oo 

Fitzgerald's  Boston  Machinist i8mo,  i  oo 

Gannett's  Statistical  Abstract  of  the  World «4mo,  75 

Haines's  American  Railway  Management i2mo,  2  50 

*  Hanusek's  The  Microscopy  of  Technical  Products.     (Winton) 8vo,  5  oo 

Owen's  The  Dyeing  and  Cleaning  of  Textile  Fabrics.     (Standage).     (In  Press.) 
Ricketts's  History  of  Rensselaer  Polytechnic  Institute   1824-1894. 

Large  i2mo,  3  oo 

Rotherham's  Emphasized  New  Testament r Large  8vo,  2  oo 

standage's  Decoration  of  Wood,  Glass,  Metal,  etc 12  mo,  2  oo 

Thome's  Structural  and  Physiological  Botany.     (Bennett) i6mo,  2  25 

Westermaier's  Compendium  of  General  Botany.     (Schneider) 8vo,  2  oo 

Winslow's  Elements  of  Applied  Microscopy I2tno,  i  50 


HEBREW  AND  CHALDEE  TEXT-BOOKS. 

Green's  Elementary  Hebrew  Grammar I2mo,     i  25 

Gesenius's  Hebrew  and  Chaldee  Lexicon  to  the  Old  Testament  Scriptures. 

(Tregelles) Small  4*0,  half  mor.    5  oo 

10 


to 


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en 


(I)     O 
Q)     ^ 


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'd  to 


siqj    tuojj 


9AOUI9J 
JOU     OQ 


OINOHOI  JO  AlISaSAINn