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WASHINGTON SUBURBAN SANITARY
COMMISSION REFUSE INCINERATING PLANT
T. L. Coleman
arch 31, 1940
Refuse Collection and Disposal
Herring & Greely
Specifications for W.S.S.C. Refuse Incinerating Plant
F.'IA Project No. 1,03. 1LWF
Incineration of Municipal Refuse
Henry ','!. Taylor
Booklet — I.odern Refuse Incineration
Pittsburg^ Des itoines Steel Co.
Consultation with C. A. Hechmer,
Operation and Design Engineer, JT.S.S.C.
Inspection of 5F.S.S.C. Plant Under the Direction of
C. A. Hechmer
This paper deals with the W.S.S.C. Incinerating plant near
Bladensburg, Maryland; the conditions of Prince George's County
which 'lade it necessary, and the manner in which it was procured
and built. I have described the plant and its equipment, the manner
of its operation and a few of the difficulties experienced by the
J.3.3.C. in its operation.
Accompanying the data dealing directly with this plant is a
resume of the different natural ways of refuse disposal which are
being replaced by the modern artificial methods, and a ~eneral account
of incineration plants, their operation, and attributes.
THE W.S.S.C. REFUSE INCIIMUTING PLANT
In treating with the subject of the "/V.S.S.C. Incineration
Plant I will first give a brief treatise of the different refuse
disposal methods, and incineration plants and disposal in general.
5IPAL .JyTHODS OF DISPOSAL
Prior to the 20th Century all of our municipal refuse was
idled in natural ways with the exception of a small amount handled
by trhee pioneering incinerator plants in New York, New York, Des
T koines, Iowas, and Ellwood, Indiana respectfully, where it was handled
by artificial means. The natural methods of handling the refuse
1, Dumping into large bodies of water — this was the most
generally employed method of our sea board and large
river cities. In this method the refuse and garbage
was loaded on barges and towed to sea where it was
dumped. This method resulted in large amounts of
garbage and trash being washed ashore and left standing
on the beaches and banks.
2. Dumping on land — this r.iethod was and in many places still
is employed around inland cities and coLiunities. These
land dumps are very insanitary as they form admirable
places for the breeding of disease carrying insects and
sources of offensive odors due to the purification of
the organic material. Dumps consisting of inorganic
matter are not so offensive but should still be covered
over with clean nev/ly excavated soil in order to enhance
3. Land filling — this .Method consists of mixing the refuse
with large quantities of fairly clean materials such as
street sweepings or excavated earth and filling in large
depressions or old excavations with this material. In
this method unobjectionaloe oxidation of the organic
matter ake place rather than purification,
/ . Planing into the soil — this nethod is adaptable to very-
sandy soils. The refuse is spread over the soil and then
turned under by plowin .
5. Burial — similar to above nethod.
6. Feeding to hogs — this is a very old and still a very
popular and economical method of disposition. The food
value of fresh garbage is sufficiently great to make
this method worth-while and many large hotels and eating
establishments have found it a profitable neans of disposal.
All of t: ■■:■■■■ bhods with the exceptions of the last are
gradually being replaced by the artificial means of incineration or
the iflcr.r/EATic;: raocEss aid n j
The incineration process has proved itself the most efficient
and practicle .eans of disposing of large quantities of refuse.
This process of incineration consists of the combination of
certain elements in fuels with atmospheric oxygen to produce heat and
therewith destroy the organic natter. This necessitates a temperature
of between 1200°F. and HQO°F. This temperature is obtained by the
corabustion of the combustible refuse or through the addition of a
fuel, In many plants this heat is also used in the conversion of
steam Tor other near by projects.
•■re are at ^resent two types of incinerators in use, the
English type which burns a mixed refuse (consisting of organic and
non-organic natter J vjithout additional fuel and the American type
which is di 1 to operate with a dditional fuel. The first
type is classified as a refuse incinerator and the second as a gar-
bage furnace. The refuse incinerator is today either hand or
.Mechanically fed depending upon the size of the plant and usually
of the top type feed.
The modern incineration plant may be located in close
proximity to the residential or business districts for with proper
operation there is no objectionable o^dors or public nuisances
created by it. The only objectionable feature to the surrounding
neighborhood being the concentration of truck traffic through
its streets. For this reason it is usually best to locate the
plant a mile or so from the closely populated areas and still not
so far away as to make excessively long hauls necessary.
A properly designed incinerator should embody the following
parts edification of design to meet engineering requirements
of the individual plant.
1. A furnace built of brick, heavily braced with structural
steel, and containing one or more cast iron or brick
-ites and ash pits.
2. An opening or special apparatus for charging refuse
into the furnace.
3« The necessary ducts, valves and blowers to deliver the
requisite quantity of air into the furnace and bring
the oxygen into contact with the combustible parts
of the refuse.
4« The necessary flues and chimney to conduct the gases
of combustion out of the furnace into the atmosphere.
The furnace may also be equipped with combustion chambers
to assure complete combustion of the refuse before the
gas is allowed to escape into the atmosphere and also
preheaters over which the escaping gases are passed.
These preheaters heat the air being supplied to the
furnace by the forced draft.
5. A means of removing the residual clinkers and ashes from
grates and ash pits (this means nay be for either manual
or mechanical extraction) .
TIE V.'.S.S.C. inCIrSgUTIPII FLAIiT
The Washington Suburban Sanitary Commission Refuse Incinerating
Plant located near Bladensburg, Maryland was built ?nd r~ut into
operation during 1939-
This plant was a necessity due to the existing conditions in
Prince Georges County brought about by refuse disposition. Prior
to 1939 the refuse of the county had been disposed of mainly by means
of ground dumps. These dumps were not regulated by any state depart-
ment until their supervision was delegated to the Sanitary Commission
by the State Legislature in 1937* The State Legislature did not,
however j delegate any funds with whieh to carry on the supervision
so that the existing insanitary conditions and public nuisances
resulting frost the ground dumps were not corrected, With the
following legislature the state authorized a bond issue for the
procurement of funds with which in conduction with F.VA Funds to
build an incineration plant.
The site of the plant and the specifications for its building
were decided upon by the Sanitary Commission. The approximate cost
was to be $55*000 and the contract to be let by the Commission to
the lowest bidder. The contract was awarded to the Nichol's
Construction Company. The site chosen by the Commission for the
constructs on of the plant was near Bladensburg south of the
Defense Highway (see accompanying map).
The plant is of the Decare type and consists of a brick
building approximately 49 ft. by 33 ft. in plan and 33 ft, high.
It consists of two floors, the top floor having direct access for
the trucks, containing the receiving floor on which the refuse is
dumped and which is equipped with four feeding doors for the furnaces,
a small office and a small lavatory. The rap approach to the
receiving floor is equipped with a large scale for weighing the
loaded and unloaded trucks.
The bottom floor which is below ground elevation on its east
side but due to the topography of the ground is above ground elevation
on the west is e ■! with two complete furnace units, each capable
of operating independently or in conduction vrith the other. These
units consist of furnaces, combustion chambers, ash pits, preheat ers,
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J/72? o^ A1/S5.C /Ak:/Afa&47Ve
ScSi.it -/* r£j>M*
flues, charging openings , dampers, drying baskets, and all other
necessary aprurtenances for the incinerator complete. The
specifications governing these units were drawn up by the commission
] closely adhered to by the contractor. All the fire brick for the
furnaces ;vas carefully inspected and required to withstand 3000 F.
The stack I'fhich stands at the southern end of the building was built
approximately 30 ft. high and capable of with standing 1800 F. varience
This plant operates without the use of any fuel other than that
supplied by the combustible elements of the refuse and occasionally
salvaged wood shavings from the Commission's wood shop to aid the
combustion. A close watch is kept of the furnaces and combustion
chambers b ■ means of temperature gages and peep holes. The force
draft apparatus is equipped with valves capable of passing the air
-en from the room at roo. . ■ ture through the preheating pipes
and thence into the furnace or directly to the furnace at room
temperature. By operation of this valve any varience of the tempera-
ture of the force draft may be obtained .d.th in the range of the room
erature and the preheating chamber.
The refuse first enters the plant from the trucks to the re-
ceiving floor. From here it is charged into the furnaces through
the charging doors, some seven square feet in area and equipped with
s inging steel doors. This charging process is accomplished manually
by two men working with forks, one on either side of the charging
door and both protected from an accidental fall into the furnace by
li f- yir-'eqc vtrivSElftl'.
Hui) n't thi-i"! i-tn I if n
means of leather belts suspended by chains to the roof of the
building. The refuse falls through the charging doors into the
drying basket. This basket is in the u^per half of the furnace
and consists of steel pipes approximately 2 inches in diameter
spaced at even intervals of approximately 1 foot and having water
continually circular them, (it is 'ere that steam is
generated but due to the varience of amount generated it has not
been suitable for any use and is exhausted into the atmosphere.)
In this drying I 'oisture is driven out of the refuse and
the solids prepared for burning, "//hen the refuse has become
sufficiently dry an operator on the furnace level will shake or
rake the refuse through the spaces of the drying cradle by means
of a long rake inserted into the furnace through the stoking doors
allowing it to fall onto the grate where it is burned. The burning
gases and particles pass from the furnace through the combustion
chamber v/here the articles are completely burned and then passed
over the preheating pipes and thence through the stack into the
The plant handles approxiiiately 35 tons of refuse per day
on a twelve hour shift, each furnace unit being capable of handle
35 tons on a 2k hour run. This allows a break down of one furnace
without Interuption to plant operation.
The actual operation is carried on by a shift of six men,
the men's hours being so scheduled that the whole shift will be
present during the rush periods and only three or four men on duty
during the period prior to operation in the morning and during
clean up period in the evening.
DIFFICULTIES OF OPSPiiTIOH
The main difficulty encountered in the plants operation is
due to the type of community served, by this incinerator. This plant
is primarily for tl rpose of disposing of the refuse of Prince
George's County, a county in which there are a great nan;'- unincorp-
erated communities vhich must rely upon free lance collection.
These free lance collectors make agreements with the residents of
a community to collect once or trice a week their garbage and trash
in return for a certain fee. The county has very little control
or regulation over these men and as a result the collections are made
at any time which the collector finds convenient. This results in
a very confusing condition at the incineration plant as it is
impossible for the operators to set up a schedule for the handling
of the refuse prior to the arrival of the trucks at the plant site.
For this reason at one time of day the receiving floor on which the
garbage is dumped nay be practically clear and the plant running
well under its capacity, immediately following this lapse in operation
the trucks start rolling in and in short order the receiving floor is
loaded to capacity, the operators over worked and the plant operating
at full capacity and still being inadequate to care for the concentra-
tion of material. This condition can be rectified only through close
regulation of collection schedules. The plant should be able to build
up its fires in the corning and when the incinerators are ready to
start operations the first trucks should roll in and these be
followed periodically through the day by other trucks thus allowing
the plant to operate steadly and never to become over loaded. Such
a collection schedule could be set up but only through close cooper-
ation of the collectors could it be carried out.
Another problem of plant operation is the separating of the
non- combustible materials (tin cans, glass bottles, etc.) from the
combustionible matter. The plant is incapable of taking care of
this incombustible refuse as the grates of the furnaces have no
mechanical means of dumping their as'nes. The ashes must be cle?ned
out by hand and if tin cans and glass v.-hich would fuse and form
clinkers was allowed to be put into the furnaces th grates 'would
quickly become clogged and the volume of unburned material which
would necessitate removal would be to great to me manually handled.
It is for this reason that the Sanitaiy Commission requires that
the collectors keep the combustible and the non-combustible refuse
seperate. In order for this to be successfully accomplished the
general public roist cooperate in this separation and not mix its
combustible and non-combustible refuse.
The plant at the -resent time takes care of the non-com-
bustible, refuse on a dump behind the building where it is carefully
cared for and covered with newly excavated earth thereby having no
ct on the generally neat aspect of the plant.
SUFERVISIOH AMD :iAINT5NANCE
The plant is under the supervision of Mr. C. A. Heckmer,
^Maintenance ^.nd Operation Department Engineer of the Sanitation
The finances for the maintenance of the plant are derived
from a charge of $1,00 per ton for the refuse burned, chargeable
to the truck operator with a minimum of $.25 per load.
This plant will ultimately form a part of a large Conmission
development as a sewage disposal plant is now in course of construction
in the same locality.