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solid waste management in high-rise dwellings
This condensation (SW—27c.l , based on reports
by the Building Research Advisory Board
of the Division of Engineering- National Research Council,
was prepared for the Federal solid waste management program
by IRENE K1EFZR
Washington, D.C. 20402 - 30 cents
Stock Number 5502f0054
U.S. ENVIRONMENTAL PROTECTION AGENCY / 1972
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Municipalities across the United States today are confronted with
the problem of handling ever-increasing amounts of solid wastes.
One of the most readily available means of simplifying the prob-
lem—but one that has received very little attention—is to reduce
the weight or volume of wastes at the source. This reduces the cost
of collection, which now ranges from $15 to $30 per ton and is
rising; at the same time, it reduces the cost of disposal.
High-rise apartments frequently use onsite incinerators to reduce
their wastes. Recent legislation aimed at controlling air pollution,
however, is now a limiting factor, either directly prohibiting use of
incinerators or requiring them to meet stricter standards than they
are capable of doing economically. Can effective and economic
incinerators be developed? Are there alternative methods and tech-
niques—some of them perhaps still on the drawing boards—that
might be used? Will they be able to satisfy environmental health
officials? Will they be reliable, effective, and aesthetically pleasing
enough to be accepted by the user? Will the price be right?
Answers to these questions may be forthcoming from a long-term
study being made by the National Academy of Sciences through its
Building Research Advisory Board (BRAB). With funds provided
solid waste management
in high-rise dwellings
Environmental Protection Agency
Library, Rasicn^V
1 North V7acker Drive
Chicago, Illinois 60606
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by the Federal solid waste management program of the U.S. Envi-
ronmental Protection Agency, a BRAB committee is developing
basic information that will not only be useful to building designers
and owners, municipal public works and public health authorities,
and city planners, but will also stimulate private industry to develop
new equipment and systems for onsite handling of solid wastes.
The study is divided into three phases, each requiring about
3 years to complete. The first phase, now well underway, has:
• Arranged for several existing high-rise low-rent apartments to
serve as a field laboratory.
* Assessed conditions there regarding such things as types and
quantities of wastes, makeup of tenant population, and limitations
of present waste-handling system.
• Installed three waste-reduction systems—incineration, com-
paction, and wet pulverization—for study in conjunction with exist-
ing central collection chutes.
• Started evaluation of the three systems.
The long-term plan calls for enlarging the project's scope from
individual buildings to a complex of buildings. Such things as
pneumatic, hydraulic, rail haul, and conveyor concepts would be
applied to an entire development. Finally, the most desirable sys-
tems—those applying to individual buildings and complexes
alike—would be installed and studied in a planned community to
determine the true economies and cost effectiveness, as well as
what municipalities would have to do to use them at the local level.
After the study got underway, the long-term plan was amended to
include consideration of a pneumatic system in the first phase of the
IRONMENTAL PROTECTION AGENCY
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study. Detailed cost estimates and engineering design have been
completed for a pneumatic system to collect wastes from a com-
plex of high-rise buildings.
the test structures
The BRAB committee first approached the New York City Public
Housing Authority on the possibility of using some of its build-
ings. The study proposed using incinerators and garbage grinders,
however, which would have required that the city waive existing
ordinances. Fearing this might delay the study, the BRAB com-
mittee decided to look elsewhere for structures typical of those in
most of the Nation's major urban centers. BRAB contacted, among
others, Chicago and St. Louis before it finally selected New Haven,
Conn., where the Public Housing Authority operated suitable build-
ings and was interested in the study.
Working out the details of the agreement between the National
Academy of Sciences, the Housing Authority, and the city, then
having the agreement approved by the Federal solid waste manage-
ment program (now part of the U.S. Environmental Protection
Agency), and the U.S. Department of Housing and Urban Develop-
ment, required about 9 months, so it was mid-1968 before the
study itself got underway.
The buildings selected are in a publicly owned, low-income
housing development about 2 miles from the center of New Haven's
main business district. Built in the mid-1950's, the development
consists of six 8- and 10-story buildings, plus three blocks of two-
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story duplex apartments. Three of the high rises are being used for
testing, and a fourth is being used as a control.
To get accurate information on the number of adults and chil-
dren using each chute, the Housing Authority management, assisted
by building residents who had been appointed as liaison between
tenants and the project, did a door-to-door census of the four
buildings. The census revealed that the buildings were occupied
by 361 adults and 695 children at the time data were gathered on
waste generation. Housing Authority regulations indicate that the
maximum allowable income for admission ranged from $3,700
for a family of one to $7,300 for a family of 14. The rate of tenant
turnover was relatively insignificant.
Each high rise is equipped with three automatically operated
incinerators located in the basement. They are flue-fed, single-
chamber, gas-fired, overfire air-blower units with an estimated
capacity of 40 pounds per hour. They are electrically programed
to fire at 2-hour intervals during the day and twice during the
night. Auxiliary fuel is supplied for 15 minutes at the start of each
firing. The hopper doors do not have automatic locks to prevent
their use during periods of burning.
Ash and residue are supposed to be removed from the incinera-
tors twice daily, placed in conventional metal containers, and stored
in the basement of each building. Twice a week the custodians use
two-wheel carts to bring the containers up the stairwells to the
street curb, where they are picked up by regular city collection
crews. At one time, permanently installed hoists were used to
carry the containers up the stairwells, but they have been aban-
doned because of continued vandalism.
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wastes generated in buildings {
The BRAB study started with an assessment of the existing sys-
tem so as to establish a bench mark against which improvements
or changes could be evaluated. In addition, the information was
needed to help select the new systems. It was particularly important
to get accurate information on how much waste and what kinds the
systems would be expected to process, and when or over what period
of time the processing would occur. Such information would also
be of interest beyond the immediate study, since little is known
about waste generation at the actual source, especially in high-rise
buildings. The BRAB committee therefore decided to determine:
• The amount of waste generated on a per capita basis.
* The variations in amounts and composition of waste with sea-
sonal changes, income level, and type of dwelling.
• The physical characteristics of the waste; such data could be
significant not only in onsite handling but also in development,
designing, and planning of collection, storage, and disposal facili-
ties on a municipal or regional scale.
BRAB contracted with York Research Corp., a commercial labo-
ratory in Stamford, to collect data for 7 consecutive days in
December 1968 on:
• Weight, volume, and physical composition (including mois-
ture content) of chute waste generated hourly, daily, weekly.
• Weight and composition of chute residue following daily
incineration.
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• Weight and composition of bulky miscellaneous waste items
on a weekly basis.
" Weight and composition of yard waste on a weekly basis.
Collecting data on chute wastes provided a bigger job than
anticipated, partly because 12 sites were involved and they were
located in four buildings. Communications were difficult. Changes
in personnel, at professional and laborer levels, meant a loss of
efficiency. The original plan called for collecting data for 3 separate
weeks, but at the end of the first week, almost all the $18,500
provided in the subcontract for field services had been used up.
During the 7 days for which data were collected, 10,947 pounds
of wastes with a volume of 1,961 cubic feet, went down the chutes
of the four buildings; the overall density was 5.6 pounds per
cubic foot. Paper was the most common constituent in chute wastes,
both by weight and volume. All the wastes contained a significant
amount of water.
On the average, each of the 1,056 tenants in the four buildings
generated 1.48 pounds of chute waste per day; considering adults
only, the rate was 4.33. The average for each dwelling unit was
6.23 pounds per day.
On an hourly basis, distinct peaks in weights sent down the
chutes occur at 9 a.m., noon, 3 to 4 p.m., and 6 to 7 p.m., with
the amounts increasing as the day goes on. The same trend is also
evident with volume, but the peaks are not as sharply defined; the
highest peak occurs at 3 p.m.
On a weekly basis, the weights of waste discarded on Saturday,
Sunday, and Monday are more than 50 percent greater than those
discarded on Wednesday, Thursday, or Friday. In general, each
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PAPER IS LARGEST COMPONENT OF CHUTE WASTES
32.98
62.61
by Volume
2638
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B
day is represented by the 24 hours ending at 7 p.m. of the day
in question. The amount of waste discarded peaks on Saturday,
with Sunday a close second; the downward trend continues through
Wednesday, when the minimum amount is discarded. In develop-
ing this curve, however, 200 pounds of waste associated with a
chute blockage on Tuesday were added to Monday's wastes. Prob-
ably some of the waste in the blockage was generated on Sunday,
which could have been enough to establish Sunday as the peak day.
The daily volume curve shows a broad, relatively flat peak from
Friday through Tuesday. In this curve, 24 cubic feet of waste
associated with the Tuesday blockage were added to Monday's
wastes.
AMOUNTS OF CHUTE WASTES INCREASE AS DAY GOES ON
-> Vol.
wt. , _,
100 - " " '"
I
8 9
AMOUNTS OF CHUTE WASTES PEAK ON WEEKENDS
WED THUR FRI SAT SUN MON TUE WED
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On the basis of 18 samples, incineration reduced the weight of
chute waste by 51 percent and the volume by 81 percent.
During the 7 days in which data were gathered, 14 bulky items—
mostly furniture, along with a few boxes—were discarded. Some
were found on the grounds and were simply assumed to have come
from the closest building.
No yard wastes were collected during the period. The janitor
responsible for yard wastes says he fills two or three 70-gallon
galvanized iron-wicker baskets daily; tenants can use additional
baskets in the front and back of each building. The contents of
these baskets weigh about 35 pounds and are composed predom-
inately of paper, leaves, and glass, in that order. Considerable
paper is blown on Housing Authority grounds when freight is being
handled at a nearby railway station.
Because of the problems encountered in the first test, BRAB
contracted for a second 7-day test in May 1971. This test, conducted
by Associated Testing Laboratories of Wayne, N.J., included collec-
tion of data needed to evaluate the new waste-reduction systems.
air pollution from existing incinerators
Because of widespread concern over air pollution from onsite
incinerators and because of the few opportunities in the past to
monitor stack emissions from incinerators of the size at the New
Haven test site, particular care was again taken to gather informa-
tion of more than immediate usefulness. The information the
BRAB committee decided to gather included:
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* Particulate emission rate in pounds per hour per pound of
waste charged.
* Percent burnout of waste sample.
" Fuel consumption.
81 Firebox temperature.
" Stack gas temperature and velocity.
m Emissions of 10 gaseous pollutants.
* Particulate loading and size distribution.
« Odor.
• Ringelmann readings for density and color.
York Research Corp. again gathered the data. Most of the waste
samples were burned in the incinerator to be replaced later in the
study by a new incinerator. In general, the samples were similar
to those determined earlier in the study. Three charging rates were
used. In addition to the design charge rate of 40 pounds per hour,
rates of 60 (to stimulate overloading and to reflect peak waste
generation periods) and 20 (to simulate underloading) were used.
Of the 51 samples burned, 23 of the standard composition were
burned in the one incinerator at design capacity; the average par-
ticulate emission rate, as measured by the ASME—PTC stack moni-
toring techniques, was 0.18 pounds per hour. Ringelmann readings
for density and color averaged 2.3 units for the 23 samples. Carbon
dioxide was low in all tests, ranging mostly between 0.5 and 1.0
percent by volume, when detected. Carbon monoxide was detected
in only a few samples.
On one set of six samples, particulate emissions were also deter-
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mined by Federal solid waste management personnel using a
method developed by the air pollution control office of EPA.
Results from this method ranged from 0.61 to 0.83 pounds per
hour, considerably higher than the ASME—PTC method. This is to
be expected, since the air pollution control office method uses a
finer filter and also measures liquid particles that were condensed
out of the gas stream.
vermin and insect infestation
Onsite waste-handling equipment is a potential source of food
and harborage for rodents, roaches, flies, and similar pests, so a
program was developed to assess the degree of infestation asso-
ciated with the existing system.
Several inspections of the basement areas revealed no evidence
of a rat population or of conditions especially conducive to rat
infestation. Tenants and the local exterminator reported that mice,
however, are a continuing problem. According to the exterminator,
the mouse population is centered around the chutes.
Cockroaches, but not flies, appear to be a problem. The BRAB
committee, assisted by officials of the National Pest Control Asso-
ciation, inspected 87 of a possible 92 apartments, essentially all
those served by the three chutes to be used with the new equipment
and by one of the chutes in the control building.
An "infestation score" was devised from the number of roaches
seen in three areas in the kitchen and two in the bathroom. Of the
87 apartments inspected, only 26 were not infested. Intensity of
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infestation varied from building to building and from apartment
to apartment within a building. No correlation could be estab-
lished between the level of infestation and the present method of
waste handling.
Factors other than the waste handling system obviously influ-
ence the level more. Roach populations were generally lower in
cleaner apartments when foods were stored in closed containers
and wastes disposed of carefully. But in some apartments, even
good housekeeping practices, plus proper storage and disposal,
did not result in freedom from infestation.
miscellaneous factors needed
to assess waste handling system
A number of other factors must also be considered in assessing
a waste handling system. Although it is desirable to have numeri-
cal data on all of them, such data are not readily available and
collecting them would require an excessive amount of time. Con-
sequently, the BRAB committee looked at these factors to estab-
lish a reasonable basis—subjective if necessary—against which a
new waste handling system can be compared. The factors:
• Personnel requirements for operating and maintaining the
existing system, including number of people at each level of
responsibility, skills required, salaries, personnel turnover, and
union affiliation.
• Power and fuel requirements, including electrical power to
operate incinerators and natural gas to help burn the wastes.
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* Costs. Only normal operating and maintenance costs are con- «j *
sidered useful for comparative purposes. IN
• Owner, tenant, and custodian acceptance. In interviews, every-
one expressed dissatisfaction with the present waste-handling sys-
tem, but no one knew alternative methods for onsite handling.
* Effectiveness and limitations. In a series of "walk-throughs",
the BRAB committee assessed these factors subjectively. The pres-
ent system is relatively convenient for tenants, with three chutes in
each building; the use of a single flue for incineration, however,
does cause problems with smoke, odor, and dust. Wastes can be
sent down the chutes at all times. Although hopper doors are small,
they will accept most normal household wastes. Bulky items will
be picked up on request within a reasonable time, but requests
are often not made. The result: wastes accumulate in corridors
and on the grounds.
Environmental conditions maintained by the system are not
particularly good. The incinerators pollute the air and produce
an odor which is especially noticeable on the roofs and when waste
is charged through hopper doors during a burning. The odor is
due in part to the low temperatures in the fireboxes during burn-
ings. The system discharged nothing to the sewers and is not noisy.
It contributes to vermin and insects, but how much is not known,
since other factors also contribute.
Aesthetically, the system leaves much to be desired. The insides
of the hopper doors are never cleaned. Litter accumulates because
the system can't handle all wastes. The 10 to 15 containers which
must be set out in front of each building twice weekly for pickup
become unsightly very quickly.
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The incinerators aren't too effective, reducing the volume of
wastes by only 81 percent. Getting the containers of incinerator
residue up the stairwell is a problem, since they weigh 70 pounds
when filled. Except for this, removing wastes from the basement
is easy; storage capacity is excellent. These are attributable more
to design of the building than the waste-handling system itself.
The system is easy to operate, the most complex part being
removal of residue from the ashpit and firebox. This job is
hampered by inability of the incinerators to burn refuse completely,
the existence of wire grates, general incinerator design, and the
absence of tools especially designed for the purpose.
selection of alternative systems
While the existing conditions at the New Haven site were being
assessed, work was also underway on selecting the three specific
waste-handling systems to be installed and on preparing preliminary
plans (architectural, mechanical, electrical, and plumbing) for
their installation. All three were installed in 1970 and their per-
formance is now being evaluated.
Compactor
Wastepactor Model No. 157, manufactured by the Compactor
Corp. of New York City, was chosen from a number of possibilities
chiefly because a comparatively large number are already in opera-
tion in the New York City area. Hydraulically operated, the unit
uses a duplex horizontal ram to force waste through a restricted
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compaction chamber. Its rated capacity is 1,500 pounds per
hour. The list price is about $4,000 f.o.b., Brooklyn, N.Y.;
the manufacturer quoted a price of $3,200 for complete installa-
tion. The easiest to install of the new systems, the compactor
merely required removal of the existing incinerator, support of
the existing flue, and extension of the flue to feed waste into the
compactor.
Pulverizer
Selection of the wet pulverizer was difficult because only two
manufacturers offered suitable units. The two units were essen-
tially the same, and neither had yet been installed in an apartment
building. A system of the Wascon Systems, Inc., of Hatboro, Pa.,
was chosen because the company said wastes could be fed directly
from the chute.
1
Compactor Installed in High-Rise Building
In the compactor installed at the New Haven test site, waste falling
through the chute passes a photoelectric cell. A horizontal ram starts forward,
pushing the waste through the compaction chamber into a discharge tube.
The top surface of the ram is equipped with a toothed shear plate which
shears any waste caught between the ram and hopper. When the ram can
go no farther, a second ram, or piston, extends from the middle and travels
through the center of the compaction chamber to clear any blockages.
Compacted waste is extruded from the 16-inch diameter discharge tube and
automatically loaded into a paper bag. When the bag is full, the compactor
shuts down and turns a signal light on. The operator can then remove the
full container and replace it with an empty one.
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The system consists of the pulper itself and a dewatering press.
Its rated capacity is 400 pounds per hour. The list price is about
$15,000 f.o.b., New Haven. Installation involved, in addition to
the measures required by the compactor, extra concrete slabbing
and curbing to provide adequate space for servicing. To take
advantage of the upward movement the system provides, the
dewatering press was installed in a laundry room on the ground
floor. The pulper waste falls directly into containers outside the
building. The manufacturer quoted a price of $9,000 for com-
pleted installation.
Incinerator
After discussions with manufacturers and consulting engineers,
the BRAB committee called on the Incinerator Institute of America
PULVERIZER INSTALLED IN TEST SITE
DISCHARGES SEMI-DRY PULP INTO CONTAINER
In the pulverizer system installed at the New Haven test site, waste
falls directly from the chute into the pulper tank, where the water is
automatically maintained at the proper level. At the bottom of the tank
is an impeller plate randomly studded with teeth. As the plate rotates, waste
falling into the tank is drawn down onto the plate, where pulpable materials
are abraded and mixed with water to form a slurry. Nonpulpables such as
metals are reduced somewhat in size and dropped into a collection chamber.
The slurry then passes through a sizing ring, which prevents oversized
particles from leaving the tank. The slurry is pumped to the dewatering
press, where it is picked up by a helical screw contained in a perforated
housing. The squeezing action of the screw extracts water (which is pumped
back to the pulper tank) and conveys the remaining semidry pulp to the top
of the press, where it is discharged into a container.
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to assist in this part of the project. The BRAB committee estab-
lished some design and performance criteria to guide the Insti-
tute's work, among which were: The unit is to be a chute-fed,
multichamber type of incinerator with at least one charging gate,
burner, overfire air supply, and gas scrubber with induced draft
fan. The system should provide for controlled charging and—if
exhaust cannot be vented in the corner of the existing chute (or
elsewhere)—for locking hopper doors during the period of burn-
ing. Under all conditions of operation, the incinerator should not
emit more than 0.2 pounds per hour on an incinerator burning
100 pounds of waste per hour; nor should the unit emit single
visible particles or observable sparkles at night. Under all condi-
tions, the incinerator should not emit smoke of an opacity denser
than 20 percent or No. 1 on the Ringelmann chart. Total hydro-
carbon emissions are not to exceed 50 parts per million (volume).
No objectionable odors are to be produced. The incinerator should
not have more than 5 percent combustible residue after incineration.
supplemental field survey
While the equipment was being selected, BRAB became con-
cerned that the results from the study might be limited to either a
particular concept (compaction, for example) or piece of equip-
ment. Manufacturers were concerned that others would interpret
the equipment selected as the best available and the data obtained
as representative or applicable to all other equipment using the
same concept.
Consequently, BRAB conducted a national field survey to collect
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This summary is based on the interim report (SW—27c.l) on Collection,
Reduction, and Disposal of Solid Waste in High-rise Multi-family Dwellings,
which was prepared by the Special Advisory Committee on Solid Waste of the
Building Research Advisory Board, Division of Engineering—National Research
Council for the Federal solid waste management program. The full report is
available from the National Technical Information Service (order No. PB
197623). The 169-page report includes 38 tables, 17 figures, and 6 appendices.
It consists of these major sections:
Abstract
Summary
Objectives and Scope of Phase I
Conduct of the Study
The Test Structures
Assessment of Existing Conditions
Preparation for Study Projection
Bibliography
U.S. GOVERNMENT PRINTING OFFICE: 1972 0—451-789
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Environmental Protection Agency
Library, E^-'icn /
1 Horth Wacker Drive
Chicago, Illinois 60606
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