Proceedings of a Symposium
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Proceedings of a Symposium
Cincinnati May 4-6, 1971
This publication (SW-4p) was compiled
by PATRICIA L. STUMP
on Agency
1 North iuacker Drive
Chicago, Illinois 60606
U.S. ENVIRONMENTAL PROTECTION AGENCY
1972
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The views expressed in these proceedings do not necessarily reflect
those of the U. S. Environmental Protection Agency nor does mention
of commercial products constitute endorsement by the Federal Government.
This is an environmental protection publication
in the solid waste management series (SW-4p).
For sale by the Superintendent of Documents, U.S. Government Printing Office
Washington, D.C. 20402 - Price $1.60
ENVIROlTMEilTAI. I^TIICTIOH AGENCY
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FOREWORD
THE SOLID WASTE DISPOSAL ACT of 1965 (Title II, P. L. 89-272) and the
~~^ broader mandate of the 1970 amendment (Resource Recovery Act, P. L.
s* 91-512) provided the means and authority to promote the demonstration,
construction, and application of improved solid waste management and
resource recovery systems.
„ Under the legislation, public and nonprofit agencies can procure Federal
i aid to study or test promising approaches that may provide actual operating
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PREFACE
IN MAY 1971, 5 years after the solid waste demonstration grant program was
initiated, the Office of Solid Waste Management Programs convened a meeting
in Cincinnati to provide a forum for status reports and discussions on projects
considered to offer the best potential for the future transfer of improved
technology. For the 3-day technical symposium, 13 projects were selected
focusing on the subjects of management systems, collection and transport,
processing, resource recovery, and ultimate disposal.
This volume contains the proceedings of that symposium. The intent is to
afford readers a better understanding of the work that has been carried out
with the support of solid waste demonstration grant funds and insight into
the possible applicability of the work to the solution of their own solid waste
management problems. The projects and studies discussed range from descrip-
tions of a mechanized collection vehicle that uses a telescoping arm to empty
refuse containers to descriptions of full facilities for converting waste to
useful products, as reclaimed materials or power.
The Office of Solid Waste Management Programs is indebted to the
speakers-the project directors and the project consultants-for their partici-
pation in this symposium. Special acknowledgment is due Frank Bowerman,
Director, Environmental Engineering Programs, University of Southern Califor-
nia, who monitored the entire symposium and provided the summation; to
Harold Gershowitz, Executive Director. National Solid Waste Management
Association, and Stuart Eurman, formerly Executive Director, Metropolitan
Planning Commission Kansas City, who along with myself, served as the
session moderators; and to Thomas C. Jones, U. S. Environmental Protection
Agency, who coordinated the symposium.
John T. Talty
Director, Processing and Disposal Division*
Office of Solid Waste Management Programs
*Formerly, Director, Division of Demonstration Operations, Office of Solid
Waste Management Programs.
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GUEST SPEAKERS AND SESSION MODERATORS
Robert M. Alexander, Jr.
County Engineer, Chilton County
P. 0. Box 87
Clanton, Alabama 35045
Ward Barstow
Division of Solid Wastes
Maryland State Department of Health
2305 North Charles Street
Baltimore, Maryland 21218
Frank R. Bowerman
Director, Environmental Engineering
Programs
University of Southern California
Los Angeles, California 90007
Lawrence Burch
Bureau of Vector Control and Solid
Waste Management
State Department of Public Health
2151 Berkeley Way
Berkeley, California 94704
Jeff Chancey
Sanitation Superintendent
City of Wichita Falls
P.O.Box 1431
Wichita Falls, Texas 76307
Anil K. Chatterjee
Senior Project Engineer
Torrax Systems, Inc.
641 Erie Avenue
North Tonawanda, New York 14120
Hugh H. Connolly
Deputy Commissioner
Office of Solid Waste
Management Programs
Environmental Protection Agency
5600 Fishers Lane
Rockville, Maryland 20852
Bernard F. Eichholz
City Manager
P. 0. Box 132
Franklin, Ohio 45005
Stuart Eurman
Executive Director
Metropolitan Planning Commission
Kansas City Region
127 West Tenth Street
Kansas City, Missouri 64105
Harold Gershowitz
Executive Director
National Solid Wastes
Management Association
1145 19th Street, N.W.
Washington, D. C. 20036
Dr. Robert K. Ham
Professor of Sanitary Engineering
University of Wisconsin
Madison, Wisconsin 53709
Howard Ness
Technical Director
National Association of Secondary
Materials Industries
330 Madison Avenue
New York, New York 10017
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Dr. Charles Pinnell
Pinnell and Associates
Box 31334
Dallas, Texas 75231
Robert Porter
Director, Des Moines Metropolitan
Area Solid Waste Agency
1705 High Street
Des Moines, Iowa 50309
William Regan III
Battelle Memorial Institute
Columbus Laboratories
505 King Avenue
Columbus, Ohio 43201
John J. Reinhardt
Principal City Engineer
City of Madison
Engineering Department, Room 115
Madison, Wisconsin 53709
Spencer A. Schilling
Battelle Memorial Institute
Columbus Laboratories
505 King Avenue
Columbus, Ohio 43201
W. 0. Schumacher
Public Works Department
City of Savannah
P.O. Box 1027
Savannah, Georgia 31402
John Stoia
General Manager
Torrax Systems, Inc.
641 Erie Avenue
North Tonawanda, New York 14120
William S. Story
Director, Scrap Metal Research and
Education Foundation
1729 H. Street, N.W.
Washington, D.C. 20006
Marc Stragier
Director of Public Works
City ofScottsdale
300 East Main Street
Scottsdale, Arizona 85251
G. Wayne Sutterfield
Commissioner of Refuse
City of St. Louis
4100 South First Street
St. Louis, Missouri 63118
John T. Talty
Director, Division of Demonstration
Operations
Office of Solid Waste Management
Programs
Environmental Protection Agency
5600 Fishers Lane
Rockville, Maryland 20852
Dr. James Walters
Sanitary Engineering Department
University of Alabama
Tuscaloosa, Alabama 35401
Ed Wisely
Homer and Shifrin, Inc.
5200 Oakland Avenue
St. Louis, Missouri 63110
Vlli
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CONTENTS
Sanitary Landfill Operations on Abandoned Strip Mines
Ward Bars tow 1
Rural Collection and Disposal Operations in Chilton County,
Alabama
Robert M. Alexander, Jr. and James V. Walters 15
Fiber Recovery Through Hydropulping
Bernard F. Eichholz 25
Refuse Milling for Landfill Disposal
Robert K. Ham, Warren K. Porter, and John J. Reinhardt. . 37
Evaluation of the Kuka "Shark" Collection Vehicle
William O. Schumacher 73
Mechanized Residential Refuse Collection
M. G. Stragier 87
An Advanced Process for the Thermal Reduction of Solid
Waste: The Torrax Solid Waste Conversion System
John Stoia and Anil K. Chatterjee 109
Refuse as Supplementary Fuel for Power Plants
G. Wayne Sutterfield and F. E. Wisely 129
Regional Solid Waste Management Authority: A Case Study
Robert C. Porter 149
The Systems Approach to Solid Waste Management Planning
Lawrence A. Burch 157
Systems Analysis Study of the Container-Train Method of
Solid Waste Collection and Disposal
JeffChancey and Charles Pinnett 177
A Review of the Problems Affecting the Recycling of Selected
Secondary Materials
National Association of Secondary Materials Industries,
Inc., and Battelle Memorial Institute 207
An Approach to Ferrous Solid Waste
William J. Regan III 221
Symposium on Solid Waste Demonstration Projects:
Some Reflections and Evaluations
Frank Bowerman 237
Registration List 241
IX
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SANITARY LANDFILL OPERATIONS
IN ABANDONED STRIP MINES
Ward Barstow*
IN JULY 1966 the Maryland State Department ofHealth, through its
Division of Solid Wastes, submitted an application for a Federal
grant to demonstrate whether or not abandoned strip mines could
be efficiently used to dispose of solid waste.
There are approximately 2,300 abandoned strip mines in the
two westernmost counties of Maryland. Over the years, mining
companies have purchased large tracts of land in Allegany and
Garrett Counties, excavated huge trenches to reach a coal seam,
and removed several feet of coal. The trenches were left open
and the spoil, or the dirt removed from above the coal seam, was
left piled around the open ditches.
DEFINING THE PROBLEM
Abandoned strip mines have long been a blight on the otherwise
picturesque western Maryland countryside. Their very presence
seems to typify the poor socioeconomic plight of persons residing
in this area. In addition, water that drains into these huge gullies
finds its way to nearby surface streams and is a major contrib-
utor to acid water pollution.
The Maryland State Department of Health felt that the use of
abandoned strip mines for the disposal of solid waste could
help in the elimination of three major problems:
1. The stripped out areas could be filled in with refuse and
the spoil material used as cover to result in a landscape that
blends in with, rather than detracts from, the surrounding area.
2. Drainage of acid mine water could be reduced or eliminated.
The accepted sanitary landfill procedure of cutting diversion
ditches around the operation and compacting and covering the
refuse with compacted earth on a slope to allow rainfall runoff
* Maryland State Department of Health and Mental Hygiene, Division of Solid Wastes.
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should eliminate acid mine water drainage originating from
runoff from surrounding areas. There is also the possi-
bility that water draining from drift mines, shaft mines, and
other strip mines could be channeled through the buried
organic matter, which could then act as an oxygen scavenger
and acid buffer to immediately retard acid formation from
these sources.
3. The strip mines could provide sites for the ultimate dis-
posal of solid waste. Strip mines in fact have certain inherent
advantages. They normally are remote and outside the range of
neighborhood objection. They are within easy access to haul
routes, since it was originally necessary to construct access
facilities so that the coal could be economically hauled from
the areas. Cover material, the spoil from the strip mine
operation, is immediately available. And lease or purchase is
economical, since no other use exists for the defunct mines.
OBJECTIVES OF THE PROJECT
The original objectives of this project were: (1) to determine
the correct procedures, equipment, and operating techniques for
efficient year-round use of abandoned strip mines for solid
waste disposal; (2) to determine any special precautions needed
to prevent ground or surface water pollution caused by water
leaching through the fill; (3) to determine the effect of sanitary
landfill operations on acid formation; (4) to determine unit costs
for disposal of solid waste under desirable conditions; (5) to
determine the unit capacity of strip mine landfills when used
for disposal of solid waste; (6) to locate the abandoned strip
mines in Maryland that are suitable for waste disposal and to
estimate their capacity for solid waste disposal.
The following objectives were included after the first project
year: (1) to determine if persons from the Work Experience
Program can be employed at sanitary landfills; (2) to determine
if a State regulatory agency can actually operate a facility within
the limits it sets for those it regulates; (3) to determine if it
is possible for several solid waste producing areas (town,
county, State or interstate areas) to proportionately share the
capital costs of such a facility if the operating costs are borne
by a central authority; (4) to determine if it is feasible to insti-
tute an area-wide cleanup and dump-elimination program in con-
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junction with a solid waste disposal facility open to the public
during normal working hours; (5) to determine the type of data
that should be collected at all central disposal facilities; (6) to
determine if it is feasible to provide intermediate disposal
facilities for those who cannot visit the established landfill
during normal working hours.
PRELIMINARY NEGOTIATIONS
The Maryland State Department of Health received notification
on November 3, 1966, that a grant for the project fiscal year
of November 1,1966, through October 31,1967, had been approved.
At that time it became necessary to secure agreements from local
supporting agencies (the town of Frostburg and Allegany County)
to contribute approximately one-third of the operating cost of
the initial sanitary landfill.
Objections to the installation of the solid waste disposal facility
were voiced by local organizations, service groups, and news
media. Representatives of the Division of Solid Wastes of the
Maryland State Department of Health attended numerous meetings
to convince community leaders that the proposed facility was not
to be just another dump. While most groups adopted a wait-and-
see attitude, the Frostburg City Council and the Allegany County
Commissioners agreed to appropriate $13,200 to the Maryland
State Health Department towards its share of the demonstration
project. In return, the State Health Department agreed to accept
solid waste generated within the boundaries of the city of Frostburg
and from surrounding areas of Allegany County. It took several
months to convince the local citizens' organizations and the
councils of Frostburg and Allegany County that this facility
would be an advantage rather than a detriment to the community.
Finally, an agreement was negotiated and signed by Frostburg,
Allegany County, and the Maryland State Department of Health
specifying the responsibilities and privileges of each participant.
The next step was to approach one of the local mineral land-
owners to negotiate a deal for the use of his stripped out property
for the project. Again, much resistance was met; but probably
because of the groundwork that had been laid, the company's
representatives were convinced that this use of the stripped
out areas would benefit all concerned. After the approval of
the State Department of Water Resources and the State Bureau
of Mines was secured, an agreement was made to use a stripped
out area southeast of Frostburg as a sanitary landfill. Incidentally,
both the State Department of Water Resources and the State
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Department of Mines gave their wholehearted approval to this
project.
Once agreements had been signed and a suitable site selected,
the site had to be prepared for an acceptable solid waste disposal
facility. The selected strip mine is located approximately 1-1/2
miles southeast of Frostburg and adjacent to the Maplehurst
Golf Course. The abandoned mine is 1,900 ft long, 50 ft wide
at the bottom, 110 ft wide at the top, and from 35 to 50 ft deep.
The first truckloads of refuse were deposited in the strip mine
on April 1, 1967. There were several reasons for the delay
between the date of award of the Federal grant and date of
initiating operation of the landfill. A public relations program
to sell local citizens on the project had to be completed. A legal
instrument designating the privileges and responsibilities of
Frostburg, Allegany County, and the State of Maryland had to
be drawn up and approved by all three government agencies.
The original budget had to be completely reworked to reflect neces-
sary changes in receipts and expenditures when it became apparent
that the original budget statement was inaccurate in many
respects. And finally, the changes had to be approved by the Public
Health Service even though the total amount of the grant was not
affected. From the outset a sampling program was instituted
to determine what effect, if any, the landfill would have on the
bacteriological, mineral, and chemical content of underground
streams. Nearby wells were first sampled before any refuse was
deposited. Samples are now being taken on a regular basis and will
continue even after the project is completed. An experienced
bulldozer operator had to be found, hired, and trained in landfill
operation. Specifications had to be prepared, and bid proposals
accepted for equipment needed at the site. Work also had to be
completed on preparing the site for acceptance of the solid waste.
SITE PREPARATION
When the site was investigated during the summer of 1966, the
pit was dry. After runoff from melting winter snows and early
spring rains found its way into the pit, however, there was about
5 ft of standing water in the strip mine.
Since the 24-in. layer of coal removed from this strip mine
rested on solid rock, it was necessary to use dynamite to construct
a 300-ft drainage ditch. After most of the water had been drained
the resulting condition of the pit dictated that additional work be
done to stabilize the base of the mine and to slope it so that any
new water would drain to the drainage ditch. All standing water
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in the strip mine resulted from either direct precipitation or runoff
from surrounding areas. A simple diversion ditch constructed
along the top edge of the strip mine eliminated the runoff problem,
and proper operation, particularly in compacting and sloping
the cover material of the landfill, has permitted access to the
fill during all types of weather for the entire period the fill
has been in operation. Since it was anticipated that snow would
probably become a major factor during the winter months, the
fill operation was started at the highest end of the strip pit so
that the length and degree of the slope of the access ramp
could be kept to a minimum and facilitate the runoff of surface
water.
Not until late April was the base of the strip mine prepared
for acceptance of solid waste. According to the terms of the
agreements with Allegany County and the City of Frostburg,
however, refuse was to be accepted from these two sources by
April 1. Adjacent to the main pit there was a smaller pit 100
ft long, 75 ft wide, and 12 ft deep that was used as a sanitary land-
fill to dispose of refuse during the 3-week period when the main
pit was still being prepared. This landfill was completed by the end
of April, covered with 2 ft of compacted earth, and seeded. The
blending of this completed landfill with the surrounding land-
scape has aided tremendously in our area-wide public relations
campaign. Visitors to the site have been able to observe the
excellent operation of the facility and at the same time to get
an idea of how the area will look when the landfill is completed.
OPENING OF THE FACILITY
By March, operation had begun at the original site. Refuse
from about 16,000 inhabitants of the city of Frostburg and the
surrounding Allegany County area was accepted when brought
in during normal working hours. Refuse received at the site
was compacted and covered at the end of each day's operation,
according to accepted procedures of sanitary landfill operation.
When the landfill was opened to receive refuse on April 1,
the only assets we had were a D-4 bulldozer, a tractor operator
with no previous experience in landfill operation, a person assigned
from the Work Experience Program of Allegany County, and the
realization by the State Health Department's Division of Solid
Wastes that the landfill operation was necessarily the best
operated refuse disposal facility in Maryland. During the first
2 months of operation, considerable time was spent picking up
paper and debris and using picks and shovels to keep the area
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neat. Such action was felt necessary to set the pace for the
operation of a model sanitary landfill. During April and May
1967, extremely heavy winds at the site coupled with the inex-
perience of the operators of the facility could very well have
caused the proposed landfill to become just another open, blowing
dump.
Each day during the first 2 months, at least one representative
(and usually more) from the groups opposing the landfill visited the
site--obviously to prove to themselves that they were correct
in opposing it. Within a few months, however, the original opponents
came to realize what a properly operated sanitary landfill is.
As a direct result of the early efforts of our personnel, the
individuals and organizations who most objected to the establish-
ment of this facility have now become its greatest admirers.
They speak in an amazed tone when they say such things as,
"I drove in unannounced and didn't even see so much as a gum
wrapper."
Meanwhile, the Allegany County Health Department opened a
campaign to remove all haphazard and illegal dumps in the sur-
rounding areas. A truck with three laborers financed by the county
visited all of the 87 roadside dumping areas within 6 miles of the
sanitary landfill. Refuse that had accumulated at these sites
over many years was shoveled onto the dump trucks and hauled
to the Frostburg disposal site. Dirt was placed over the abandoned
dumps and signs were posted informing persons that dumping
was no longer permitted at these sites. During this entire period,
a concentrated newspaper, radio, and television campaign was
waged to inform the public that the laws against haphazard dump-
ing would be enforced and that a sanitary landfill had been
established in the area. So far, 24 of the 87 dumps have been
eliminated.
Although weighing facilities were not yet present at the site,
we attempted to estimate the amount of refuse that was being re-
ceived at the site during the first 5 months of operation. The
County Roads Department and the County Health Department have
confirmed that haphazard dumping in the area has decreased during
these same months.
DEVELOPMENT OF ADMINISTRATIVE FACILITIES
During the first 2 months of operation most efforts were
directed toward establishing a true sanitary landfill operation.
During this same period, however, specifications were being
drawn for bid submissions on the water system, sewerage system,
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platform scales, and administration building. When bids on the ad-
ministration building came in almost 50 percent higher than
expected, and when representatives of the Maryland State Depart-
ment of Water Resources advised us that the first available water
strata lay below an underground shaft mine, our thinking had to
be reevaluated.
Investigations revealed that an office trailer could probably be
purchased for somewhat less than what was originally estimated
for an administration building and almost half of what a new building
would cost under the terms of the lowest bid received. A trailer
also has the advantage of being easily moved from one site to
another. Bid specifications were drawn up and a bid was accepted
on an office trailer measuring 10 ft by 36 ft. The trailer includes
two desks and chairs, electrical wiring and lighting, refrigerator,
shower, toilet, wash basin, drafting table, two heat pumps, and a
storage locker. The total cost for this facility is $3,820.
A half-acre farm pond located within 400 ft of the site of the
office trailer contains about 8 ft of water. Analyses of water
samples indicated that, with treatment, this pond could be our
source of water. Bids were let for equipment to pump, pipe, and
treat this water. The equipment included a 1/3-hp. centrifugal
pump, a positive displacement hypochlorinator, and a pressure
anthracite filter. The water supply system, was constructed under
permit from the Allegany County Health Department, using as
labor personnel of the department and employees at the sanitary
landfill. Although so far all samples collected in the trailer have
tested negative for organisms of the coliform group, this water
system has not yet been certified as a potable water source
because of the turbidity that still remains.
Bids were also prepared and the low bid accepted for construction
of an underground sewage disposal system. A permit has been
issued by the Allegany County Health Department.
Meanwhile, the various types of truck scales available were
discussed with several scale companies, and it was concluded
that a Thurman portable truck scale would be best suited to our
needs. The scale selected has an 80,000-lb capacity and its
platform measures 10 ft by 25 ft. The platform was installed,
ramps were constructed for access and egress by the vehicles,
and the area under the scale platform was boxed in using old
railroad ties. A time and date stamping device was also installed
so that weights and quantities of refuse received at the site could
be correlated with the time it was brought in.
To fulfill the objectives of the first phase of this demonstration
project, it was necessary to collect additional data on which to
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base conclusions. In determining what data should be collected
for future analysis, the need for uniform data collection throughout
the State was considered. In other words, though the data col-
lected at the Frostburg landfill has a direct bearing on the
conclusions reached about the operation of this particular facility,
the aim is to develop a system that can be used at all major
refuse treatment, transfer, and disposal facilities in Maryland.
After a thorough study of the type of data that is particularly
required for this site, for those developing a comprehensive
statewide plan, and for those planning or operating major refuse
facilities, it was determined that in addition to the weight, time,
and date, the following information should be collected: vehicle
number, vehicle type, type of refuse, source of refuse (the
general area from which the refuse is received), and weather
conditions (including both temperature ranges and precipitation).
While the type of data was being determined, various methods
for collecting this information were also being considered.
After investigating many methods of data collection, it was
concluded that the most efficient would be to code the information
so that it could be printed directly on data processing cards.
The cards could be processed through a keypunch machine with
a keypunch operator reading the material from the card and
punching the data into the same card. It was also concluded that
the best way to print this information on the card was through
the use of a designating key module. This piece of equipment
consists of a keyboard (somewhat resembling the keyboard of a
calculator) of 10 columns each of which contains digits 0 through 9.
This machine is attached in a vertical position directly beside the
dial face of the scale. Numbers punched on its keyboard will
print out on paper inserted under its stamping device.
The operation of the designating key module was correlated
with the design of data processing cards and the administration
of the facility so that the following routine of data collection is
practiced:
1. The loaded collection vehicle drives onto the scale plat-
form.
2. The weighmaster observes the number of the vehicle and
sets the scale fulcrum for the empty weight of the vehicle.
Where the empty weight is not known the weighmaster records
the gross weight as the vehicle passes over the scale, and
the tare weight when it returns from the landfill. The tare
weight is then subtracted from the gross weight to give the
net weight of the refuse received at the site, and the tare
weight of the vehicle is recorded on a separate sheet for
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future reference. Variances in the number and weight of
the occupants of the vehicle and variances caused by modifi-
cations in the vehicle will probably even out in the long run.
Random samples of tare weights of vehicles will, however,
continually be checked throughout the project period to deter-
mine if variances in the tare weights of the vehicles fall
within reasonable confidence limits.
3. Keys on the designating key module are then depressed
by the weighmaster to reflect the information to be recorded
by that device.
4. The data processing card is inserted into the guide area.
5. The button on the scale is depressed, activating the
machinery that prints out the weight and coded factors in
the appropriate spaces on the data processing card, and the
vehicle is waved off the scales.
6. The card is inserted into the time and date machine so
that this information is printed in the appropriate spaces on
the card.
7. The cards are stored for later punching by the keypunch
operators for ultimate data retrieval.
Although a computer program for data retrieval has not yet
been developed, it was evident that if this data collection and
retrieval system were to blend in with information collected at
other major refuse facilities throughout the State, it would be
necessary to establish a statewide solid waste facility permit
system, with the permit numbers designating such things as
year of issue, county and election district in which the facility
is located, site number within the county, and type of facility.
The purchase and installation of this data collection system costs
$6,758 ($6,271 for the portable platform scales, $262 for the
designating key module, $75 for the time and date recorder,
and $150 for 100,000 data processing cards).
COSTS
By using the scale, it was possible to keep records in relation
to cost per ton. During the first year and a half or so of this
project, cost figures could not be calculated as accurately as
desired because both site Nos. 1 and 2 were placed in operation
before the scales were installed. Every effort was made, however,
to keep as accurate records as possible. It is interesting to note
that during the project's 5-year life, the population presently
being served by this facility has increased from 16,000 to more
than 50,000, and that the tonnage has increased from 30 to 40 tons
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10
a day to as much as 300 to 500 tons a day, (approximately 30 or
40 percent is industrial).
During 1970, the project operation cost was $1.45 per ton,
which includes amortization and interest on capital expenditures,
and direct operating costs. Some items that are acceptable at a
demonstration project of relatively short life cannot, however,
be considered for a new model facility. The $250 surplus dump
truck, for example, would be replaced by a new truck costing
$13,000 to $15,000. A more substantial equipment service build-
ing, separate sanitary facilities for landfill operating personnel,
and sanitary facilities for delivery truck drivers are additions
to the site development that can be expected at a sanitary landfill
that is not established as a demonstration project. Conversely,
the amortization period for the site development costs would
be extended for a longer fill life, which would help to offset these
additional costs.
ACID MINE DRAINAGE STUDIES
In compliance with the requirements of the grant for the Allegany
County project, the first of six filter beds were constructed at
site No. 2 in Westernport. The first filter bed test pit was filled
on January 18, 1969 (Figure 1). The purpose of these pits was
to determine what effect acid mine drainage would have on
different types of solid waste.
A total of 362,380 Ib of general refuse was compacted in this
bed with a compaction rate of nearly 1,000 Ib per cu yd. This
bed was then sealed with a plastic cover and no water was pumped
into it until June 16. At this time, 7,500 gal were pumped into
the pit. On June 23, 2,250 gal were again pumped. Starting on
July 9, 500 gal were pumped each day until July 18. Again on July
21 and 22, 500 gal were pumped.
Initially very little effluent passed into the septic tanks and sand
filter on the downstream side. The pH of the acid mine water was
raised from an average of 3.7 to about 5.9 (Table 1).
In passing througn the test pit, most ol the yellow color and
slime growth that was due to the iron and sulfur was removed from
the water. Chemical samples have been collected for analysis,
but at this writing, the results have not been released by the
laboratory. Extreme organic interference was noted in some of
the initial tests. Considerable odor was also noted.
Preliminary observations indicate an initial enhancement of the
pH with an accompanying removal of iron. There is also a
degradation of the water through formation of the organic acid
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IX
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TABLE 1
CHEMICAL RESULTS AND SUPPLEMENTAL DATA FOR FILTER BED
STUDIES, JULY 1968
Source
Item
Day
Color
Turbidity, (units)
PH
Chloride, ppm
Nitrate, ppm
Total solids, ppm
M.O. alkalinity, ppm
Hardness as CaCOs , ppm
Iron as Fe, ppm
Sodium, ppm
Stream
1
25
20
3.7
42
0.04
3,274
-44
386
75
23
16
37
37
3.6
18
0.60
3,304
-163
883
85
17
Tank No. 1 before Tank No. 2 after
sand filtration sand filtration
1
60
320
5.6
937
46,792
4,881
673
1,200
975
16
500
180
5.6
834
21,842
3,596
...
650
1,075
1
45
90
6.0
497
9,770
23,392
...
600
625
16
55
120
5.9
699
13,142
2,494
117
600
775
and other soluable putrescible material, however. On a larger
scale, it is felt that this could be controlled economically with
chlorine.
Before being discharged, the effluent is run through a sand
filter, after which it is retained in a chlorine contact chamber
before being pumped into a nearby stream.
Plans are being made to continue these studies during the
summer and fall months as long as the weather permits.
RESEARCH STUDIES
During the last 2 years of the project, research efforts have
been expanded. Thirteen wells were installed at site No. 1 in
an effort to learn more about the possibility of contaminated
substances moving through the soil. Three of these wells, desig-
nated as landfill observation wells A, B, andC (Figure 2) were in-
stalled in the center of the landfill itself. Also, 10 additional
ground water observation wells were installed adjacent to the land-
fill on the north side.
Samples collected from the ground water wells on the north
side of the landfill contained lead and cadmium. The presence
of these metals does not confirm that they originated in the
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landfill, since they occur naturally in coal deposits in Maryland,
West Virginia, and Pennsylvania.
Neither lead nor cadmium was found in the samples of leachates
collected from the landfill wells A, B, and C. Boron tracers
seeded in the landfill wells were not found in samples of water
collected from the ground water wells. As a result of these
studies, it can be concluded that so far there has not been any
movement of leachate from the landfill to the ground water
observation wells. Samples from these wells will continue to
be taken in an effort to note any changes.
Chemical analysis of samples of leachates from landfill wells
A, B, and C revealed high levels of phenol, oils, and grease, as
well as heavy metals, all of which inhibit the growth of most types
of microorganisms. Metabolic inhibitors might very well be
present as organic solvents, detergents, strong acids and bases,
and organic enzymes.
Interestingly enough, aerobic spore formers were found in
this anaerobic environment. It is suspected that these may be
faculative anaerobes functioning as aerobes because of the pres-
ence of some oxygen.
Limited studies conducted on the effects of percolating acid
mine water through accumulations of solid waste on the filter
beds at site No. 2 revealed that the resulting filtrate exhibited:
(1) a greatly increased iron content, (2) an increase in pH,
(3) increased BOD, (4) increase in color by iron and sulphur
compounds, and (5) objectionable odors.
CONCLUSION
In conclusion, it should be mentioned that over the past 5
years, this project has set standards for the establishment of
sanitary landfills throughout the State of Maryland. As a regula-
tory agency, the Division of Solid Wastes of the Maryland State
Department of Health has benefited tremendously, because the
demonstration project provided the opportunity to function as
an operating agency and thereby enabled the Division to better
understand the many facets of solid waste disposal through
sanitary landfilling. As a result of this 5-year experience, we
have been placed in a better position to advise and serve the people
of Maryland.
This project has been supported by demonstration grant No.
G06-EC-00048 from the Environmental Protection Agency, pur-
suant to the Solid Waste Disposal Act as amended.
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RURAL COLLECTION AND DISPOSAL OPERATIONS
IN CHILTON COUNTY, ALABAMA
Robert Alexander, Jr.,* and James V. Walters f
UNTIL RECENTLY, county engineers in rural areas were seldom con-
cerned with the storage, collection, and disposal of solid wastes.
Now those engineers find that like so many other aggravating
environmental problems, solid waste management is claiming
an increasing amount of their professional time and energy.
Few of the rural areas served by public highways have any
system for the collection and disposal of solid waste generated
by local residents and businesses. Despite the conscientious
effort of the vast majority of the rural population to come up with
satisfactory methods of waste disposal for individual households,
much of this material comes to rest within the rights-of-way of our
public highways. Increases in population densities and in the amount
of waste generated by each person have combined to cause dramatic
increases in the quantity of waste being deposited along our
rights-of-way in recent years. Particularly because of the
difficulty and cost of removing such materials, county administra-
tors have become much more interested in initiating and operating
collection and disposal programs that would prevent such despoil -
age of our highways.
Project CLEAN AND GREEN is an example of the efforts
of one county to solve its solid waste problems on a unified basis.
The project represents a partnership of the Chilton County govern-
ment with the governments of the county's four municipalities,
Clanton, Jemison, Maplesville, and Thorsby.
Chilton County lies in the geographic center of Alabama and
is traversed by Interstate Highway 65. The Coosa River is its
major eastern boundary. Nearly a tenth of its 699-sq mile area
lies within the Talladega National Forest. Timber and other
agricultural efforts dominate its land use, but the prime economic
resources of the county are the many industrial enterprises
that have grown up there. The 1960 population of Chilton County
*County engineer, Chilton County, Clanton, Alabama.
fPh. D., P. E., Professor of Civil Engineering, University of Alabama, Tuscaloosa,
Alabama.
15
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was approximately 26,000. The approximate population in the in-
corporated municipalities were: Clanton 5,700, Jemison 1,000,
Maplesville 700, and Thorsby 1,000.
ENVIRONMENTAL CONDITIONS BEFORE
PROJECT CLEAN AND GREEN
Before Project CLEAN AND GREEN began, the environmental
conditions relatable to solid waste disposal in Chilton County
were similar to those found in most rural counties of Alabama
today. Solid waste in municipalities was being collected house-
to-house and disposed of by dumping and burning. Waste generated
by rural families was disposed of by the individual householder
wherever he could most conveniently throw it, and waste generated
by transients was rather thoroughly distributed along the county's
highways.
Each of four municipalities operated a dump and burned wastes
there to reduce their volume. The odor and smoke from these
operations were objectionable, and in each case, the capacity of
the site was nearing completion.
In the rural areas, householders had created and used approxi-
mately 40 major unauthorized dumps, and many more small dumps
were observed along the roads of the county. In an effort to
reduce the hazards and undesirable conditions resulting from this
large number of unauthorized dumps, the county had previously
attempted to encourage the use of dumps in four specific locations
where the landowners were agreeable to such use of their property.
County equipment was sent periodically to cover the accumulation
of waste with soil. With only four dumping areas in the entire
county, however, the haul distance discouraged the householders,
who mostly ignored the county's efforts and continued to dispose
of their wastes at the unauthorized dumps.
The amount of waste generated at the boat landings on the river
had prompted the county to locate 55-gal steel drums near the
landings and in the adjacent picnic areas. The containers were
well received by the public. For several years sportsmen had
cooperated by placing wastes in the containers, which were
periodically emptied by county personnel. Ultimate disposal
was at one of the existing dumps. Another costly service the
county was forced to provide was the cleanup of the right-of-
way along its highways.
The situation finally caused the governing bodies of the county
and its municipalites to come together for serious consideration
of their solid waste disposal problem. The factors that compelled
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them to adopt an improved program of waste disposal were
the unacceptable conditions resulting from the unauthorized
county dumps and from the municipal dumps, the cost involved
in cleaning up solid waste strewn over large areas along the
highways, and the relative scarcity of land for future dumps.
COUNTYWIDE SOLID WASTE DISPOSAL SYSTEM
The unsatisfactory conditions caused by dumping and burning,
the scarcity of land for future dumps, and the extremely high cost
of operating individual sanitary landfills for each municipality
led the governing bodies to consider the use of one centrally
located sanitary landfill. Because the county also had solid waste
disposal problems and because the selection of a central disposal
site would necessarily be outside the boundaries of at least three
of the municipalities, it was reasonable that the county be chosen
for major responsibility in implementing a central landfill project.
The responsibility for administration of the operation was placed
in the county engineer's office in order that the personnel and
equipment of that office might be made available for the con-
struction and other nonroutine activities proposed for the project.
Since the municipalities already owned and operated municipal
collection equipment, it was decided that they should continue to
be responsible for the door-to-door waste collection within their
corporate limits. The cost of door-to-door collection in the rural
portion of the county prohibited its consideration. But because
the rural householder was already carrying his waste some
distance to one of the unauthorized dumps, it was felt that he
might be expected to deposit it in a suitable container located at
no greater distance than he was accustomed to. Later, the waste
could be collected and taken to the central landfill.
The countywide system chosen for implementation includes
continued door-to-door collection by the municipalities of waste
generated within their corporate limits, collection by the county
of rural waste from approximately 60 approved container sites,
and satisfactory disposition of all solid waste generated in Chilton
County by placement in a central sanitary landfill. Operation
of the rural collection system and rehabilitation of all the existing
dumping areas was made the responsibility of the county engineer.
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Central Sanitary Landfill
The county was fortunate to already own a parcel of land
that appeared to be a satisfactory site for the landfill operation.
Evaluation of that site was initiated by a survey and topographic
mapping of the property. Alabama's State geologist was helpful
in evaluating the geology of the plot. To verify his inferences,
a subsurface investigation was performed by personnel of the
county engineer's office. Soil borings at the site were advanced
below elevations to which landfill operations are expected to occur.
Soil samples from these borings were analyzed to evaluate their
water carrying characteristics and their suitability for use as
landfill cover material. The sand-clay soil sampled by the
borings performs very well as a landfill cover. The boreholes
opened during soil sampling were used for observations of the
ground water table. Water table observations allowed planning
for all waste to be placed above the existing water table elevations
over the proposed fill areas at the site. When full evaluation of
the site confirmed its desirability, it was possible to begin site
preparation and construction of operating facilities. All other
operations of the new system were dependent on the initiation
of the central landfill.
For documentation of the landfill operations, it was necessary
to install scales to weigh all waste deposited there. The scalehouse
was planned to provide shelter and sanitary facilities for landfill
personnel and to allow office space for the landfill manager.
An all-weather road was constructed to provide access from the
nearest paved county road. The access road subsequently has been
paved. Fencing was erected to prevent uncontrolled entry to the
site and undirected deposition of waste before and after the normal
hours of operation. Waste receptacles were installed just outside
the gate to allow deposition of waste at those times. The utilities
required by the scalehouse were electricity, water, and telephone.
The need for gas and sewer services was avoided by the use of
electric heaters and a septic tank. The major item of equipment
necessary for the landfill operation was the tractor, which was
purchased to place, compact, and cover deposited wastes. In
addition to the landfill bulldozer, several pieces of county equip-
ment were used for site clearing and road building operations.
The 33-acre landfill site is relatively hilly and is contiguous
with both highway I-65 and the county airport at Clanton. Utilization
of the site has been planned so that waste will be placed at the lower
elevations on the property, and cover material will be excavated
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from the tops of the hills. The full effect of the plan will be to
improve the surface shape of the ground by making it more
uniformly sloped, and to uncover two large areas of undisturbed,
preconsolidated soil suitable for the support of buildings. The
areas that will be filled can be used to store commodities that
are not undesirably affected by subsidence of the surface that sup-
ports them or for such purposes as playgrounds or parking lots.
The improved surface shape and the 3/4-mile proximity to the
nearest 1-65 interchange should make the undisturbed areas of
the site very desirable for the construction of an industrial or
institutional facility.
Personnel required to operate the central landfill have been the
manager, the operator, and the utility maintenance operator.
Under supervision of the county engineer, the manager directs
operation of the facility, weighs all wastes deposited, and maintains
records of the activity. The operator drives the bulldozer to
compact and cover the wastes. The utility operator directs
individual trucks to the proper spot for waste discharge, helps
maintain the cleanliness of the site, can relieve either of the
workers in the event of illness, and performs other duties to be
mentioned below in the rural collection operation.
Full operation of the central landfill was begun during September
1968. As soon as the site became available for waste disposal,
efforts were turned to closing the existing dumps.
Dump Rehabilitation
From the outset it was apparent that implementing a rural
collection system would be pointless unless disposal at the
unauthorized dumping areas was terminated. To mark the termi-
nation of unauthorized dumping and to remove the hazards that
past dumping had created, rehabilitation of the old dump areas
was planned. A most important facet of dump rehabilitation was
rodent eradication.
Chilton County's sanitarian, Mr. C. C. Gay, Jr., planned this
rehabilitation function in conjunction with personnel from the
Alabama State Department of Health and from the U. S. Environ-
mental Protection Agency. Their eradication plan called for initial
poisoning with red squill in a bait composed of sardines and rolled
oats. Secondary poisoning was with Warfarin in coarse corn meal.
Evaluation of the effectiveness of the poisoning was to be based
on rodent population surveys before and after the poisoning.
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When surveys indicated that satisfactory eradication had been
accomplished, a bulldozer was brought to the site to bury all
waste. The area was then dressed and seeded in a manner that
emphasized the posted notice that the area was no longer to be
used for the disposal of solid waste.
A D-7 bulldozer was the only equipment required to rehabilitate
all but the Clanton dump. There, three bulldozers, two 15-cu yd
scrapers, and one motor grader were used to excavate a hole in
the middle of the area, move the waste material into the hole,
and finally cover the entire area with a graded, compacted soil sur-
face. To date, approximately 50 dumps have been rehabilitated at
a cost slightly in excess of $12,500. This cost, including equipment
costs, based on national average rental rates averaged about
$390 per acre for the 32 acres of dumps rehabilitated.
The rehabilitation of the rural dumps had to wait, of course,
until the countywide system of rural collection was in effect and
able to provide an acceptable alternative to the old dumps.
Rural Collection System
Several criteria were used in selectingprobable container sites.
Containers should be located near existing unauthorized dumps to
take advantage of the householders' old habits, but they should be
far enough away to spacially separate the two concepts of disposal.
They should be located within the county road right-of-way
and in a position that would pose no hazard either to persons
depositing waste or to the driving public. During initial planning
for the project, it was not certain whether the State Highway
Department and the Bureau of Public Roads would allow the use
of their rights-of-way for container sites. Since then, however,
an evaluative trial of three such sites has been negotiated. A
third criterion was to place a container within 10 min of driving
time of the vast majority of the rural homes in Chilton County.
The final criterion was that container sites had to be located along
a route that could be served by a single piece of collection
equipment, since the purchase of two packer trucks would be
beyond the financial resources of the county. The distances involved
in the tentative collection routes required the use of the largest
easily maneuverable loader-packer body available on a standard
truck frame. A 30-cu-yd E-Z Pack packer body was chosen
for mounting on an International cab-over-engine truck frame.
The packer body, truck frame, and sixty 4-cu-yd containers were
the equipment originally purchased for use in the rural collection
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system. By November 1969, 43 container sites had been imple-
mented. The 43 sites accommodated 57 containers and were
located in such a manner that 50 percent of the rural households
were nearer than 1.6 miles to the closest site, 90 percent were
nearer than 3.7 miles, and 95 percent were closer than 4.8 miles.
Additional sites have been implemented since then, making a
total of 79 containers now in use at 60 sites. A dozen other
containers owned by the county board of education are located
at schools for their specific use, but the waste is collected by
the project's collection truck. To improve the all-weather utility
of the rural collection system for the public, all container sites
located on county road rights-of-way have been paved.
The essence of the rural collection system is graphically
presented in Figure 1. For clarity, only major arteries and roads
used as a part of the collection routes are shown.
As it exists presently, the countywide solid waste collection
system comprises two collection routes. There are 23 container
sites along the northern route, which is approximately 90 miles
long. The southern route is approximately 125 miles long and
passes 37 such sites. The two routes are serviced on alternate
days, thus providing collection from each container three times
a week. The personnel assigned to the collection activity and
routine maintenance of the packer truck are the packer-truck
driver and the utility operator mentioned above who also serves
as a relief driver.
It was thought desirable to have a half-ton pickup truck dedicated
to the waste disposal operation of the county in order to use it
for cleanup around the rural waste-collection receptacles. All
personnel of the county engineering department are responsible for
observing conditions at the various receptacle sites as they go
about their normal duties. Use of a two-way radio system allows
immediate reporting of any undesirable conditions and makes
possible quick correction of the conditions by the cleanup crew.
One or more operating personnel from the landfill perform such
cleanup services.
With the beginning of rural collections in January 1969, the entire
countywide solid waste disposal system became operational.
Experience reported here covers approximately 2 years of landfill
operation and about 18 months of rural waste collection.
During the first 20 months of sanitary landfill operation,
5.2 acres of the site received 12,100 tons of waste, which occupies
a volume of 19,100 cu yd. The average density of the waste as com-
pacted is approximately 1,270 Ib per cu yd. About 28,300 cu yd of
soil were used to cover the deposited wastes. Though such a volume
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of cover material may seem high, about 6,000 cu yd of this soil
were used to construct a barrier between the exterior of the first
(and lowest) landfill cell and the creek. The average thickness
of the barrier wall is about 15 ft. Even allowing for that construc-
tion, the volume of cover material used is excessive. But for this
particular site, the only cost of fill is the cost of tractor fuel,
and selected excavation of the higher elevations on the site does
result in ultimate site improvements.
The cost for a typical month of operation is about $6.75 per
ton for the rural collection system (Table 1) and about $2.06
per ton for the central sanitary landfill (Table 2).
The trend since the beginning of the countywide system has been
for the amount of rural waste collected to increase from month to
month. Since, however, the major cost items are relatively inde-
pendent of the amount of material handled, it is anticipated that
unit costs for rural collection will be somewhat reduced before the
system reaches its capacity. (Increased demand for service is
one result of initiating such a system.) The effect of increased
utilization of the system on the unit cost is dramatically shown
by comparing the unit cost for the month shown in Table 1 ($6.75
per ton, 184 tons of waste collected) with the unit cost for the
same month during the previous year ($10.17 per ton, 116 tons
of waste collected). One portion of the cost that is not known with
certainty is depreciation. For instance, the estimated life for
the rural packer truck was set at 6 years. If this estimate proves
to be inaccurate, depreciation cost would vary from those
presented.
Other results of the rural waste collection system are less
technical and much more readily recognizable. Anyone riding
through Chilton County before and after the beginning of Project
CLEAN AND GREEN could surely see the difference in a country-
side now free of dumps. Anyone familiar with the former open
burning municipal dumps would readily notice the cleaner air.
Crews responsible for mowing highway right-of-ways have given
unprompted reports of the dramatic decrease in cans, bottles,
and parcels of waste they encounter daily. The most important
overall result of Project CLEAN AND GREEN is that it demon-
strates the availability of a practical countywide solid waste dis-
posal system that almost any rural county can afford to adopt.
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TABLE 1
COST OF RURAL WASTE COLLECTION FOR A REPRESENTATIVE MONTH*
Item Amount
Labor $ 454.12
Fuel and supplies 198.59
Repair and maintenance 171.00
Equipment depreciation 373.82
Supervisory costs 45.00
Other 0
Total cost 1,242.53
Total unit cost per month 6.75 per ton
*Based on a total of 184 tons of collected waste.
TABLE 2
COST OF CENTRAL SANITARY LANDFILL OPERATION
FOR A REPRESENTATIVE MONTH*
Item Amount
Labor $ 649.12
Fuel and supplies 47.17
Utilities 77.14
Equipment repairs 6.71
Equipment depreciation 521.85
Supervisory costs 350.00
Total cost 1,651.99
Total unit cost per month 2.06 per ton
*Based on a total of 803 tons of deposited waste.
This project has been supported by demonstration grant No.
G06-EC-00178 from the Environmental Protection Agency, pur-
suant to the Solid Waste Disposal Act as amended.
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FIBER RECOVERY THROUGH HYDROPULPING
Bernard Eichholz*
THIS IS THE STORY of the solid waste disposal and reclamation
facility being built by the city of Franklin, Ohio, with the assistance
of the Federal Office of Solid Waste Management Programs.
Located in southwestern Ohio in the valley of the Great Miami
River, Franklin is a small city of 10,000. About 4 years ago,
it became apparent that Franklin was rapidly exhausting its solid
waste landfill. Concerned city officials, and in particular,
councilman Joe Baxter, Jr., decided to investigate the possibility
of pulping solid waste using paper mill equipment, removing the
metal and glass centrifugally, and dewatering and burning the
remaining material in a fluid bed reactor. Mr. Baxter is an
engineer with the Black Clawson Company, a company engaged
in the manufacture of papermaking machinery in Middletown,
Ohio, 5 miles from Franklin.
The Great Miami River Valley is dotted with paper manu-
facturers who located in the valley to avail themselves of the
plentiful underground water. This abundant supply of underground
water provides not only the huge volumes of pure water necessary
for the paper manufacturers, it is also the source of water supply
for some 1.5 million persons living in the valley. Under these
circumstances, landfilling of solid waste could be a potential
health hazard to the millions of persons whose water supply might
be polluted by the decaying garbage.
ESTABLISHING AND DESIGNING THE SYSTEM
The idea of pulping solid waste was presented to the Federal
Office of Solid Waste Management Programs, and as a result,
Franklin received a grant to design and construct this innovative
facility. The Black Clawson Company set up an operational pilot
plant in their Middletown plant as an aid to the design and eventual
operation of the Franklin facility. The city retained A. M. Kinney,
Inc., consulting engineers, Cincinnati, Ohio, to design the plant and
*City manager, Franklin, Ohio.
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oversee its construction, since this firm had been instrumental
in the development of the Hydrasposal process.
Suprisingly, the scope of the project began to expand. The
Black Clawson engineers wondered if paper fibers from the waste
could be reclaimed, since 50 percent of municipal solid waste
is paper. A. M. Kinney, Inc., was therefore retained to design
a fiber reclamation system to be integrated with the Hydra-
sposal system. The fiber reclamation system will extract reusable
fiber along with metals and glass. The possibility of extracting
glass attracted the attention of the Glass Container Manufacturers
Institute. Now the City and the Glass Container Manufacturers
Institute, with financial assistance from the Office of Solid Waste
Management Programs, are adding a glass sorter that separates
the aluminum from and then sorts the glass into three colors:
clear, amber, and green.
The Franklin Environmental Control Complex
During the preliminary studies it was discovered that sewage
sludge- -raw, digested or activated- -could be mixed with the organic
waste from the solid waste operation, dewatered without coagu-
lants, and disposed of with the organic waste.
Armed with this knowledge, Franklin began planning for a new
sewage treatment plant that would save the construction and operat-
ing costs of sludge digestion facilities. The Miami Conservancy
District, Dayton, Ohio, a public authority responsible for water
resource management in the Miami Valley, proposed that the
District design, build, own, and operate a regional waste-water
treatment plant alongside and in conjunction with the new solid
waste plant. Necessary authorizations were obtained, and the
Franklin Environmental Control Complex was born.
Approximately 230 acres of land on the outskirts of Franklin,
very close to the existing inadequate sewage treatment plant,
were made available to the Conservancy District. The District
acquired the property and then leased to Franklin a couple of
acres upon which to construct the solid waste plant.
The two plants will in fact be right next to each other. From
a process standpoint, the liquid and solid waste plants are mutually
dependent upon each other.
• Process and scrubber water for the solid waste plant will be
effluent from the secondary clarifiers.
• Waste process water, about 50 gpm, from the solid waste
will be treated in the water treatment plant.
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• Primary and secondary sludge from the water treatment
plant will be mixed with organic waste of the solid waste
plant and burned in the fluid bed reactor.
• Ash containing scrubber water will be mixed with the industrial
waste water and used as a settling agent in the industrial
clarifier.
• The two plants will share certain common services--potable
water, fire service, access road, etc.
There obviously will be some clean, washed, inorganic residue
remaining from all this processing--perhaps about 5 percent of
the original volume--and this can be safely and sanitarily land-
filled in an area adjacent to the solid waste plant.
Still another very vital function for the combined facility will
be the disposal of residues consisting of crank-case oil, spray
booth offals, and other nonaqueous liquid wastes. They are normally
dumped and cause serious ground and water pollution problems.
It is believed that the fluid bed reactor installed in connection
with the solid waste disposal facility is also capable of disposing
of these liquid industrial residues, and a program for testing
this feature of the facility is included in the design.
The fluid bed reactor is a type of furnace uniquely suited to
burning the unsalvageable portion of municipal and industrial
waste. In our case it is a vessel approximately 24 ft in diameter and
30 ft high. There is a perforated plate in the bottom covered with
about 4 ft of sand.
During operation, air is blown through the perforated plate and
up through the sand to keep the sand in suspension. At first the
fluidized sand is preheated to 1,200 F by oil burners. Then the
refuse is introduced into this hot fluidized bed. As the minute
grains of sand come into contact with the finely chopped waste
material, the result is complete incineration. Combustion of the
waste maintains the temperature, and no further addition of heat
is required. The products of combustion are discharged from the
reactor at 1,500 F, which is sufficient to eliminate all odors.
These gases are then cooled and washed with water in a scrubber
to remove the ash.
Because of the publicity received by this facility, inquiries have
come from persons and businesses all over the world who are seeking
a place to dispose of their waste-truly a growing problem, soon to
reach crisis proportions. These inquiries reveal the glaring fact that
most of the inquirers have been dumping their waste in hollows,
creek beds, etc. Now, at long last, the spotlight is revealing their
actions and nature is rebelling.
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ESTIMATED COSTS
Estimated construction cost for the Hydrasposal plant is $2
million. The glass sorter alone will cost $225,000. These estimates
do not include the adjacent regional sewage treatment facility
being constructed by the Miami Conservancy District.
The plan is to start operations in June 1971, with a disposal
charge of $6 per ton. The economics of the plant are such that
if Franklin were a larger city, this unit cost could be reduced
to as low as $3 per ton. In fact it is possible that even Franklin
might receive a great enough volume of solid waste to result
in a rate of $3 per ton. Obviously, if the volume justifies a second
8-hr shift, the economics change radically, since the fixed
charges, such as amortization, insurance, demand electrical
charges, etc., can be spread over two shifts.
PLANT OPERATIONS
The Franklin solid waste plant will very nearly duplicate the
pilot plant (Figure 1). Essentially unsorted municipal refuse is
loaded onto a conveyor and fed into a specially modified Hydra-
pulper. Pulpable and friable materials are reduced in size until
they will pass through the 3/4-in. diameter openings in the ex-
traction plate beneath the rotor. They are then pumped away as
a slurry of 3 to 3.5 percent consistency.
Nonpulpable materials, mostly tin cans and other ferrous
objects, are ejected from the side of the Hydrapulper into a
continuous junk remover. The tin cans are balled up, and wire
and other small objects cut into small pieces. This material is
washed and the ferrous metals removed magnetically.
The slurry from the pulper is then subjected to a number of
rather typical papermaking operations. The first step is to remove
larger inorganic particles in a Liquid Cyclone. The inorganic
rejects from the Cyclone contain about 80 percent glass and 20
percent aluminum, other metals and just plain dirt. The glass
concentrate will be cleaned and sorted for recycling as described
later in the paper.
The next operation is to defiber small pieces of paper and to
screen out nondefiberable organics such as plastic, leather, tex-
tiles, twigs, etc. This is accomplished in a V R Classifiner, which
has a high-speed rotor operating against a screen with 1/8-in.
diameter perforations.
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'^& """!"""«
Figure 1. Partial view of pilot plant showing Hydrapulper in background.
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30
The material that passes through the 1/8-in. perforations is
diluted to a .5 percent consistency, then passed through a conven-
tional paper mill screen with 1/16-in. openings. The balance
of the stringy, nonpapermaking fibers are removed in this
operation.
Very fine sand and shives are next removed in centrifugal
cleaners, and the cleaned slurry is passed over a surface screen
to remove fine fibers, etc.
The rejected material from the three screens and the centri-
cleaners, mostly nonrecoverable organics, is combined with sludge
from the sewage treatment plant, dewatered to about 40 per-
cent solids in a press, and burned in a fluid bed reactor.
The accepted stock from the last screen is dewatered, cooked
in mild caustic, washed, dewatered and baled for shipment.
Figure 2 shows the completed Franklin plant.
The plant is designed for a nominal capacity of 150 tons of
municipal refuse per 24-hr day. Current plans are to operate
only 8 hrs per day. It is anticipated that the following materials
will be recycled per 8-hr day:
Paper fiber 8-10 tons per day
Ferrous metals 4-5 long tons
Glass cullet 2-3 tons (future)
Aluminum 400 - 500 Ib (future)
Liquid Waste Processing
The Miami Conservancy District, under the leadership of
Wesley A. Flower, Chemical Engineer, designed the waste-
water treatment plant to incorporate the newest technologies and
to take advantage of the adjoining solid waste plant. The basic
flow sheet is shown in the upper portion of Figure 3.
Municipal waste water will be introduced from the existing
collection system and pass first into a conventional gravity
clarifier with flocculation chamber. Detention time is 3 hr.
Via a junction chamber, the clarified overflow then will be passed
through three aeration basins in series for secondary treatment.
Each basin has a capacity of 9 million gal. Basin No. 1 has
two 75-horsepower fixed aerators, Nos. 2 and 3 have two 50-
horsepower fixed aerators each. The basins are of earthen construc-
tion with clay seal, and aerator agitation is designed to prevent
settling. Retention time is 6 days.
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31
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Two secondary clarifiers are provided, arranged for parallel
operation. Retention time is 3 hours. The clarified effluent will
be chlorinated before returning to the Miami River. Expected
BOD of the effluent is 20 to 40 ppm.
The sludge from the secondary clarifiers, a biological ash
that is essentially inert, will normally go to the industrial primary
clarifier, though a portion may be diverted into the municipal
clarifier.
The industrial waste water will be collected in a separate
sewer system and introduced into a separate primary clarifier.
Tests have shown that the effluent from four paper mills--a
cotton fiber mill, a white paper mill, a cylinder board mill, and a
roofing felt mill-contains mostly inorganics and that the sludge
can be landfilled with no further treatment. The overflow from the
industrial clarifier will be combined with the clarified municipal
water and treated as described above.
Design parameters are given in Table 1.
TABLE 1
DESIGN PARAMETERS FRANKLIN SOLID WASTE PLANT
Design data
Capacity, as received 150 tons/24 hr
Building area 11,000 sq f t
Connected horsepower 1600 hp
Operating data
Scheduled operation 8 hr/day
5 days/week
Tons waste to be processed 40-50 tons/day
Tons sludge to be processed 7 tons/day
Number employees 4
Process water 50 gpm
Scrubber water 112 gpm
Auxiliary fuel 0
Fuel required for cold start 25 00 gal
THE FUTURE
Two additional operations are in advanced engineering stages
for the Franklin complex.
The Glass Container Manufacturers Institute (GCMI) has spon-
sored research work on recovering glass cullet from solid waste,
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34
and especially from the glass concentrate rejected from the
Liquid Cyclone. The concentrate is dried, screened, magnetically
cleaned, and then air-classified to obtain a relatively pure mixed
glass cullet, with particle sizes ranging from 1/4 in. to 3/4 in.
This glass is then color sorted by a Sortex optical separator.
This machine discriminates between different shades, and will
sort the glass particles into clear (flint), amber, and green-
the color sorting required for glass container manufacture.
One of the byproducts of the air separator is an aluminum con-
centrate, which is currently being evaluated by the aluminum
companies.
The Miami Conservancy District has studied the problem of
handling nonaqueous commercial and industrial liquid wastes in
the Miami Valley. They have determined that each week some
75,000 gal are generated for which no disposal facility is presently
available. In composite, these waste liquids have a calorific value
of about 4,500 Btu per lb., almost adequate for autogenous
combustion. The fluid bed reactor has been used successfully
in many applications of waste oil and oily sludge burning.
The solid waste plant is scheduled to operate only 8 hr per
day; the fluid bed reactor can handle residual combustibles from
the operation in about 6 hr. Oily liquid wastes could be incinerated
during the remainder of the day.
The Miami Conservancy District is engineering a tank farm
and blending station to be installed beside the solid waste plant.
The waste liquids will be delivered by private contractors,
stored, blended, and burned during the off-hours of the solid
waste plant. Work is also underway to recover the copper
and lead values and the rare metals, and to convert the non-
recoverable organics into energy.
CONCLUSION
It is believed that when the glass sorting and nonaqueous waste
facilities are completed, this plant will be the first in the world
to treat municipal sewage, industrial waste water, nonaqueous
liquid wastes, and municipal refuse on the same site; to recover
paper, iron, aluminum and glass in recyclable condition; and to
accomplish this with no pollution of the air or the land.
This is the Franklin story, originating in a small community
of 10,000, which feels gratified and proud to play a part in offering
a solution to one of our Nation's most vital and pressing problems.
Perhaps it can best be expressed in the words of the plaque to
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35
be erected on the facility: "Dedicated to the Citizens of this small
Community who had the foresight and the courage to save the
purity of the land entrusted to them by God."
This project has been supported by demonstration grant No.
G06-EC-00194 from the Environmental Protection Agency, pur-
suant to the Solid Waste Disposal Act as amended.
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REFUSE MILLING FOR LANDFILL DISPOSAL
Robert K. Ham,* Warren K. Porter, f and John J. Reinhardtft
IN EARLY 1966, the Heil Company approached the city of Madison
with a proposal to utilize the services of the University of
Wisconsin and jointly investigate the European concept of milling
refuse and placing it in a landfill without daily cover. The
Europeans claimed that in milling the refuse, its characteristics
are changed in such a manner that rodent and insect vectors are
not a problem, blowing paper is nil, vehicles can travel across
it in wet weather, and accidental fires are easily controlled.
In other words, many of the operational problems of the sanitary
landfill are minimized and the reasons for daily cover are
eliminated.
The city of Madison investigated the proposal and agreed to the
concept if funding under the Solid Waste Act of 1965 could be
obtained. After submitting the applications, the city of Madison
was awarded a grant in June 1966 to pay up to two-thirds of the
costs; one-third of the costs were required to be paid by others.
Arrangements for the project were as follows:
1. The Heil Company furnished and installed the equipment
and provided the technical assistance necessary to adapt the
equipment to American refuse. They also provided the
matching funds in the amount of $116,000 for the equipment
and the project evaluation by the University of Wisconsin.
Under terms of a purchase option contract, the equipment
could be bought by the city of Madison at the end of the
project if it proved successful. (The city of Madison purchased
the equipment in 1969V
2. The city of Madison provided the site, site improvements,
operating personnel, and the combined refuse as needed,
and the matching funds ($69,000) for this portion of the
project.
3. The University of Wisconsin was retained to gather the data
and evaluate the project as an impartial third party.
* Professor, University of Wisconsin.
f Program director, University of Wisconsin Extension.
•jf Principal civil engineer, city of Madison, Wisconsin.
37
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38
The general objectives of the original project were three-
fold:
1. To evaluate economics and operating problems of (a)
the French-manufactured Gondard ballistic rejection mill
and feed conveyors, (b) the final disposal system for the
milled refuse (which consisted of a Barber Green rubber
belt conveyor and Heil Load-Lugger containers with a hoist
truck), and (c) the management of such a plant.
2. To investigate the milled refuse itself and compare it to
unmilled refuse.
3. To investigate the procedures and European claims for
using the milled refuse in landfill without daily cover.
The original project was to a large extent a developmental
project. In late 1968, experience indicated that milling refuse was
a promising enough approach to Madison's sanitary landfill
problems to warrant an enlargement of the project. At the same
time, the Heil Company became interested in evaluating the
English-manufactured Tollemache hammermill, which has a
vertical shaft and a ballistic rejection feature. They were also
interested in cooperating with the city of Madison and using
the experience gained during the project to revise the existing
facility to solve the problems of feeding the refuse to a mill
and taking it to the landfill. The new project consisted of addi-
tional tests on milled refuse and installing and/or evaluating
the following items: (1) the Tollemache mill; (2) a feed system
for the Tollemache mill consisting of a short, direct-feed bin
conveyor with metal flights; (3) a stationary packer with self-
unloading, 75-cu-yd transfer trailers; (4) building expansion to
allow operating two shifts; (5) the Tollemache mill and Gondard
mill operating at the same time to mill about 280 tons per day
in a two-shift operation.
A two-year renewal grant was received from the U. S. Environ-
mental Protection Agency to cover part of the plant operating
expenses and finance the conveyor modifications, stationary
packer, transfer trailers, and additional evaluation work by the
University of Wisconsin.
DESCRIPTION OF THE ORIGINAL SYSTEM
The original Gondard milling system consisted of a scale,
a building, a storage hopper, conveyors to transport the refuse
to the mill, a French-manufactured Gondard mill, a conveyor
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39
to transport milled refuse from the mill to the haul-away vehicle,
and a truck to haul the milled refuse to the landfill (Figure 1).
The original milling system is centered about the Gondard
hammermill and consists of the necessary material handling
equipment in addition to the pulverizer. The refuse fed to the
Gondard mill is either ground finely enough to pass through a
grate or is sent ballistically by the impact of hammers up a
chimney and out of the mill. The ballistic rejection feature enables
the mill to operate nearly continuously, with little or no hand
sorting or monitoring of the feed going into the machine. The
French-manufactured Gondard mill and conveying equipment were
used in the plant because of Gondard's considerable developmental
work with this type of equipment at the time of the original
project.
The refuse is first weighed at the scale and then emptied inside
the building into a storage hopper or onto the floor when the
hopper is full. A front-end loader pushes refuse from the floor
into the storage hopper as needed. The bottom of the storage
bin is a metal-slated conveyor that carries refuse through an
opening at one end of the storage bin, where two rubber belt
conveyors carry it to the Gondard mill. Refuse was stored in
both the bin conveyor and on the floor to eliminate the need
for an overhead crane and operator and to minimize the need
for materials handling. The bin conveyor is driven by a 15-
hp. motor connected by a hydraulic coupling to a variable-speed
drive. The variable-speed drive allows the flow of refuse to be
controlled by increasing or decreasing the speed of the conveyor
belt.
Two rubber belt conveyors are used to lift the refuse to the
mill, where it is dropped onto the hammers through the side of
the chimney. The conveyors provided the change in direction so
that the size of the building could be kept as small as possible.
The hammermill is of a standard design except for the ballistic
rejection tower over the mill. The mill consists of a 6-in. main
shaft around which is mounted four subshafts. Each subshaft
contains 12 hammers weighing 15 Ib each and measuring 1 1/4 in.
by 4 in. by 11 in. The hammers (Figure 2) have a shaft through
one end so that they can stand out by centrifugal force and pul-
verize the refuse. The mill is operated at approximately 1,200
rpm by a 150-hp. motor. The unique feature of the mill is the
chimney placed over the top to allow rejection of items that would
clog the machine.
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40
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Originally, both the pulverized refuse and the ballistically re-
jected items were discharged onto a conveyor that emptied into
a conventional refuse collection truck that took the refuse from
the plant to the landfill. At first, 10-cu-yd bins with a load-lugger
truck were used to carry the milled refuse from the mill building
to the landfill. The system was chosen on the basis of European
milled refuse densities in an uncompacted state. The densities
of uncompacted milled refuse at Madison, however, were con-
siderably lower, and the 10-cu-yd bins were too small to handle
the volume of milled refuse efficiently. A 25-cu-yd refuse packer
truck with a continuously cycling compaction blade was tried
next. The unit proved successful forthe8-ton-per-hourproduction
rate of the Gondard mill, but it was inadequate for the 15-ton-
per-hour production rate of the Tollemache mill.
THE TOLLEMACHE INSTALLATION AND PLANT EXPANSION
In early 1969, the Heil Co. of Milwaukee requested permission
from the city of Madison to install and test an English-manu-
factured Tollemache vertical shaft hammermill in the existing
refuse milling plant. Permission was granted in the summer of
1969. The Tollemache mill was installed next to the Gondard
mill in such a manner that it could discharge milled and rejected
material onto the discharge conveyor of the Gondard mill. A new
feed system design was based on 2 years of experience with the
original Gondard system that indicated that mill production was
mainly a function of the rate that refuse could be fed into the
mill and carried to the landfill after processing. The Tollemache
feed conveyor consists of a 45-in. wide metal flight conveyor
that fits into one end of the Gondard bin conveyor. The Tollemache
feed conveyor operates in the opposite direction of the Gondard
bin feed conveyor and feeds directly into the Tollemache mill
without changing the feed direction to the mill.
The Tollemache mill has a funnel shape (Figure 3) that can
be combined with three different diameter rotors to allow dif-
ferent types of grinding to take place. The rotors and shafts
are mounted in a vertical plane and the hammers swing in a
horizontal plane~an arrangement that is the opposite of the
Gondard mill. The funnel-shaped top section and top hammers
act as a prebreakdown section that reduces loading on the mill
motor by allowing hard-to-grind items to be chewed to pieces
before they reach the next set of hammers. The funnel section
also serves as a ballistic rejection mechanism. Items that are
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43
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hard and are not ground finely enough to pass through the 41-
in. neck section of the mill are spun around the funnel and out
a reject chute by the ballistic force of the hammers. The 41-in.
neck acts as the grates do in the Gondard mill. The particle size
is also partly controlled by the hammer pattern and hammer
length at this point. The three rotors are mounted on the central
shaft, which turns on bearings located at the bottom and the top
of the shaft. Each rotor has six subshafts on which the hammers
are mounted. The hammers are 10 in. by 4 in. by 1-3/16 in.
and weigh 15 Ib. The original hammer pattern contained 54
hammers, but early experience with the mill showed that this
number of hammers produced a grind that was much finer than
needed for landfill purposes. Various hammer patterns have
been tried, and the first evaluation of the mill was done with a
32-hammer pattern. Presently, a 34-hammer pattern is being
used. The hammer tip diameter in the top rotor is 33 in., the
middle set is 38 in., and the bottom set is 43 in. The mill is
driven by a 200-hp., 440-volt, squirrel-cage, high-torque motor
at 1,300 rpm.
The unmilled refuse enters the mill at the top on one side of the
funnel where the hammers in the prebreakdown section reduce
large items. Smaller-sized particles fall down into the throat
of the mill where they are ground as they fall through the hammer
set. The material then falls down to a set of hammers that grinds
the material and throws it out the side of the machine onto a con-
veyor belt. This set of hammers does most of the work.
Other Plant Modifications
Early in the project it was recognized that economics were
largely a function of the scale of operation and that the original
installation was only a pilot plant if one considered the total amount
of millable refuse in the city of Madison. Studies of ways to expand
the pilot plant into a larger scale facility indicated that a reasonable
approach would be through a number of steps that would allow
the city to capitalize on experience gained in the early years of
the project. In 1968, a plan was developed that consisted of the
following major parts: (1) addition of a second mill to allow a
two-shift operation based on a plant production rate of 280 tons
per day; (2) expansion of floor storage to allow a second shift
operation; (3) revision of the materials-handling system for the
milled refuse to reduce the labor required with the load-lugger
bin system and the refuse packer truck system that had been
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45
used to that time; (4) operation of a second shift to reduce the
depreciation cost per ton.
The first step taken after the installation of the Tollemache mill
with the new feed conveyor was the installation of a materials -
handling system to handle the milled refuse from the mill to the
landfill. The modifications (Figure 4) consisted of: (1) the installa-
tion of a 4-ft-wide Barber Green rubber belt conveyor to carry
the material from both the Gondard and the Tollemache mill
to a small, 36-in.-wide rubber belt conveyor that transferred
milled refuse to a stationary packer in a building addition adjacent
to the mill; (2) the installation of a stationary packer unit that
loads a 75-cu-yd transfer trailer; (3) the use of a 75-cu-ft
transfer trailer that has its own motor and ejection plate to
unload the trailer at the fill site.
PLANT OPERATIONS
Much information is available on pulverizing refuse in the
Gondard machine. For the Tollemache pulverizer, cost and pro-
duction information is limited since it is based on an evaluation
of the 3 months since installation and completion of a break-in
period. The data on the Tollemache machine was obtained from
Mr. Gerald Sevick, project specialist for the University of
Wisconsin.
The tonnage processed per hour is not a direct reflection of
the machine capacity because the feed conveyors, mill, and haul-
away system operate in series. Thus, the whole system is only as
strong as its weakest link. The Gondard mill was the strongest
link in the original processing system. Until February 1969, the
mill was never fed at an average rate of more than 60 percent
of theoretical power consumption, despite improvements in the
feeding apparatus. The feed is still irregular (perhaps because
of the heterogeneous nature of refuse) and is a definite limitation
on the plant capacity.
The Tollemache mill was installed in late 1969 and underwent
a break-in period until May 1970. An evaluation of milling
combined, residential refuse was conducted during a 14-week
period from July through early October 1970. At the same time,
the stationary compactor and transfer trailer were installed
to handle the combined output of the two mills.
Over the period of the project, many improvements have been
made in the plant operation. These improvements include, for
example, placing vertical sides and rubber cleats on conveyors
to assist in material flow, and providing quicker access to the
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46
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hammermill. Actual downtime due to clogging of conveyors
and jams in either mill are no more than 15 min. per day. However,
the results achieved in the operation of the plant are based on
operation of the pulverizers for 5.3 hr per 8-hr day. In addition
to the downtime attributable only to the milling operation (jams
of feed conveyors and the mill), there were considerable periods
of nonproductive work. In an attempt to quantify these nonpro-
ductive work times, the daily records when only the Gondard
was in use, from April 1 through November 29, 1968, were
examined. The average number of minutes per day of nonpro-
ductive work are itemized as follows:
Minutes
Elapsed time between arrival of first load of refuse and start of milling 33
Conveyor and mill jams 13
Nonproductive time during milling:
Out of refuse 15
Truck breakdown 12
Lunch 19
Other 4
During the same period, there were 37 recorded cases of hammer
maintenance and 24 cases of general maintenance, all of which
account for some of the nonproductive work time listed above.
Two things should be noted: (1) many of the shutdowns could be
eliminated through proper initial design (this is something
that is gained only by experience and is the purpose of such a
demonstration project), and (2) other shutdowns could be reduced
or eliminated by rearranging work schedules.
More recent experience with the Tollemache indicates that
the daily average downtime that is due to jamming of the mill
is less than 5 min. Because of the higher capacity of the Tolle-
mache, the plant has been out of refuse for an average of 1/2 hr
at least once each working day. The consequences of this situation
are threefold: (1) continuous operation of the mill is interrupted;
(2) overtime hours are required to complete daily operations;
(3) all refuse entering the plant could not be ground because of
overtime restrictions.
To increase the productivity of the plant, working hours are
being revised to start the first shift at 11 a.m. Incorporation
of additional storage space, which is now completed, should
permit continuous operation at a high production rate.
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48
Operating Data for the Gondard Hammermill
The Gondard machine is constructed with a screen in the
bottom through which refuse must pass after being pulverized.
During the year of experimental trials, the grate at the bottom
of the mill was changed systematically to determine the optimum
grate size or clear space between the bars of the grate. Con-
siderations included machine capacity, operating costs, landfill
space usage, and particle size-all of which vary with grate
size and season. Thus, three grate sizes were used each season.
Initially, 2-in., 4-in., and 6-in. grates were used. However, use
of the 2-in. grate was discontinued after the first trial, since
it pulverized the refuse finer than required for landfill, slowed
production, and thereby raised costs. The 4-in., 5-in., and 6-in.
grates were therefore used throughout the remainder of the
experimental phase of this project.
Production Aspects. The overall production rate of the Gondard
machine (Table 1) is the tonnage processed during mill operating
time plus downtime charged against the milling (conveyor and mill
jams, for example). Not included in the overall rate is time lost
because of exhausting the supply of refuse, truck breakdowns,
lunch, and time lapse between arrival of the first load of refuse
and the start of milling operations. These items were not included
in the overall production rate because they are not directly caused
by machinery limitations. Instead, these are personnel and
supervisory matters. The lost time cannot merely be set aside:
it does in fact exist and will continue to exist with even the best of
supervision. The question is, how much can the downtime be
reduced?
TABLE 1
THE GONDARD HAMMERMILL:
RELATION OF OVERALL PRODUCTION RATE TO GRATE SIZE
Average rate for last full year
Projected average ratef
3'/2-in. grate
8.3
8.4
Tons per hr*
5-in. grate
7.4
9.0
6lA-'m. grate
7.7
9.4
*Includes both operating and shutdown time.
f Based on installation of cleats to improve feed to mill.
From September 1967 through January 1968, the rejectable
items were separated into a bin and weighed. During this time it
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49
was found that 1 to 7 percent of the total refuse could be ballis-
tically separated when the reject chute extended vertically
27 ft above the mill.
As indicated before, the mill was not operated at theoretical
capacity. Theoretical capacity will probably never be reached
because of mate rial-handling problems associated with the hetero-
geneous nature of refuse. A load factor, or the ratio of power
consumed to theoretical power consumption, was computed as
a rough indicator of how hard the machine worked compared to
its theoretical capacity. The average load factor ranged from
0.6 to 0.7, depending on the grate size used.
Cost Data. Cost data are presented for the third and final year
of this demonstration project, from June 1968 through May
1969. Although it is proper to report the costs incurred at
the existing plant, one must be cautioned about adapting these
costs to other installations. This project is a pilot plant demon-
stration whose operation is probably more expensive than that
of future plants. The regional variations in labor, power costs,
heating costs, and depreciation methods must also be taken into
account. The section on cost projections gives a more accurate
indication of what future plants might cost. These projections
indicate costs per ton ranging from $3 for one mill operating one
shift, to $1.30 for four mills operating two shifts.
Furthermore, the unit costs (Table 2) are higher for the
pilot plant than they would be for a larger plant of different design.
Some of the reasons for the higher unit costs are as follows:
(1) refuse is not conveyed to the mill as fast as the mill can grind;
(2) a similar plant without extra conveyors and the extensive
foundations necessary for the site's soil conditions would be less
costly; (3) a plant using one mill and having proper haul-away
equipment might be operated by two men, thereby reducing labor
cost; (4) the plant is not milling refuse for 7 hr daily for reasons
indicated previously.
Hauling costs are not included in this section. Land costs
are excluded because they are commonly omitted from other
studies, and because this plant was built on an existing city site
purchased many years ago. Administrative costs are also commonly
omitted since they vary with the organization.
The costs per ton (Table 2) are calculated on an annual cost
basis in which the annual cost is divided by the projected annual
tonnage. The annual tonnage is calculated by using the overall
production rate, the average number of operating hours per
day, and the number of operating weeks per year.
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50
TABLE 2
THE GONDARD HAMMERMILL: RELATION OF COST PER TON TO GRATE SIZE
Item
Labor
Amortization
Power
Lighting
Water
Gas heat
Hammer wear
Mill maintenance
Small equipment
General supplies
Front-end loader
operation
Other
Total cost
Annual cost
$39,800
32,200
Variable
2,300
200
1,200
1,660-1,710
850-950
800
1,100
500
1,700
/ton
3V4-in. grate,
10,750 tons/yr
$3.70
2.99
.34
.21
.02
.11
.16
.08
.07
.10
.05
.16
7.99
Cost per ton
5-in. grate,
11, 5 00 tons/yr
$3.46
2.80
.30
.20
.02
.10
.15
.08
.07
.10
.04
.15
7.47
6lA-in. grate,
12,050 tons/yr
$3.30
2.67
.30
.19
.02
.10
.14
.08
.07
.09
.04
.14
7.14
Refuse Composition and Characteristics of Milled Refuse
An important qualification of any refuse processing system is
the composition of the wastes being processed. Samples of combined
refuse have been analyzed physically and chemically. Personnel
from the Office of Solid Waste Management Programs made
physical analyses of the waste in November 1968 (Table 3).
A physical analysis was also made of the milled refuse to quantify
the particle size. This analysis was made to relate particle
size to possible problems of blowing litter in the landfill. Samples
of milled refuse pulverized through different sizes of grates
were shaken through a sieve commonly used for aggregate
analysis in road construction. This method is tenuous but to our
knowledge is the best method available for making such a quanti-
fication. The range of particle size was determined for 3 sizes
of grates (Table 4).
The most noticeable features of the milled refuse are that it
is homogeneous and that its individual components, such as
newspaper and plastic bottles, are not recognizable. Milled
refuse has an appearance of oversized confetti or torn newsprint.
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TABLE 3
RANGE OF COMPOSITIONS OF SOLID WASTES, WET BASIS*
Item
Food waste
Garden waste
Paper products
Plastics, rubber, leather
Textiles
Wood
Metals
Glass and ceramics
Rocks, dirt, ashes, etc.
Minimum
4.4
0.0
35.1
0.3
0.1
0.0
5.0
4.4
0.6
Percent of total
Maximum
28.9
31.1
53.2
3.7
7.8
2.6
14.5
17.6
17.6
Average
15.3
13.8
42.4
1.8
1.6
1.1
6.7
10.1
7.2
*Moisture content varied from 30 to 48 percent, with an average of 37 percent.
TABLE 4
SIZES OF PARTICLES PROCESSED IN THE GONDARD HAMMERMILL*
Percent of particles finer than
Grate size
3Vi-in.
S-in.
6%-in.
Sin.
99
93
91
2 in.
97
87
83
lin.
74
67
59
0.5 in.
46
42
38
*Excludes ballistically rejected items and cans.
Many of the tin cans are crumpled. The glass is disintegrated
and appears as small chips approximately 1/8 in. by 1/8 in.
The milled refuse appears to be bulkier after it comes out of
the mill than before it went in. The bulking, which is thought to
be due to the pulverizing of paper and paper products, is the
reason that the original detachable-containers system proved to
be undersized and was soon replaced with mechanical compaction-
type collector trucks as a means of hauling the milled refuse to
the landfill. When using mechanical compactors in good operating
condition, we have achieved densities of 650 to 700 Ib per cu yd
in the haul-away truck, compared to less than 350 Ib per cu yd in
the incoming collection trucks used in 1967.
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Tollemache Hammermill Operation
Production Aspects. Based on the 14-week evaluation, data is
provided on production capability and costs. Extensive experi-
mentation was done during the break-in period to determine the
hammer pattern needed in the Tollemache. Unlike the Gondard
mill, the Tollemache has no screen through which pulverized
refuse passes. The hammer pattern is thus the prime determi-
nant in the fineness of the grind and in the production capacity
of the machine.
Overall production rates (Table 5) include downtime attrib-
utable to the milling equipment and conveyors. The mill was
operated an average of 5.3 hr per day. The plant production
per day should be increased by the revisions in plant operating
hours and more efficient utilization of personnel.
TABLE 5
OPERATING AND OVERALL PRODUCTION RATES
FOR THE TOLLEMACHE HAMMERMILL
Period
July 6-31
August
September
October 1-9
July 6-October 9
Tons
Milled
1,480
1,573
1,701
564
5,318
Time (hours)
Operational
100.4
104.9
122.5
38.0
365.8
Overall
104.0
107.7
125.3
38.3
375.3
Production rate (tons/hr)
Operational
14.72
15.01
13.89
14.82
14.53
Overall
14.22
14.62
13.58
14.72
14.18
Cost Data. Costs encountered during the 14-week evaluation
are tabulated in Table 6. In areas such as depreciation, where
an expense occurs over a longer time than that covered in the
evaluation period, expenses were proportioned to the evaluation
period.
During the 14-week evaluation period, 5,320 tons of refuse
were milled. The resulting cost is $26,200 per 5,320 tons or $4.92
per ton. Again, this figure is based on operating the mill only
5.3 hr per day. As in the case of the Gondard mill, the unit
cost could be lower if the plant did not require excessively costly
foundations because of soil conditions onsite, and if the plant
were operated for 7 hr per day. Continued development, revisions
of operating hours, and provision of more storage to permit
two-shift operation should enable reduction of these unit costs.
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TABLE 6
COST OF 14 WEEKS OF OPERATION OF THE TOLLEMACHE MILL
Item Cost
Labor $13,378
Depreciation* 9,760
Hammers 657
Power 1,390
Hammer shafts 72
Welding rods 177
Plant supplies 153
Tractor maintenance 112
Front-end loader maintenance 171
Transfer trailer maintenance 30
Water
Lighting 278
Total 26,178
*Depreciation would be lower if a common building were
erected. Since this building is constructed on poor soil, a very
expensive foundation had to be provided.
COST PROJECTIONS FOR FUTURE PULVERIZING FACILITIES
One of the purposes of a demonstration project is to determine
information that will have wide application. This part of the
presentation lists some basic engineering design information
on the milling process for use by others planning similar in-
stallations. Factors, such as machine capacity to be used in
making cost projections are listedfirst. Cost projections are made
in the last section bv using the basic data and other estimates.
The following list and Table 7 contain recommended figures
to be used in making cost projections. The list itemizes factors
that apply to both the Gondard and Tollemache mills:
Production aspects:
Operating hours and days Maximum of 7 hr per 8-hr
work shift; 245 days per year
(49 weeks).
Labor requirements A minimum of 2 men for a
one mill in a building located
at the landfill.
Fringe benefits 30 percent (exclusive of over-
time).
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Depreciable life of equipment "Butler" type steel building - -
20 years. Weight scale -- 20
years. Front-end loader - - 8
years. Grinders and conveyors - -
15 years.
Interest rates (Nov. 1969)
for municipality 5.8 percent on municipal bonds.
7.0 percent on general fund.
Wearable parts in Gondard mill .... Grates and wear plates - - 8,000
tons. Welding rods --80 per
set of hammers, at cost of
$.50 per rod.
Transportation:
Capacity of truck 6 tons on a 25-cu yd packer.
Depreciation life of truck 10 years.
Landfill:
Density of milled, combined
refuse 870 to 1,090 Ib per cu yd for
refuse characterized in Table 5.
Apparent density of raw refuse
with intermediate cover 570 Ib per cu yd (including
volume of cover dirt).
Actual average depth of cover
dirt 6 in. on milled refuse, 15 in.
on raw refuse.
TABLE 7
COST PROJECTION FACTORS: PRODUCTION ASPECTS
Amount
Item 3%-in. grate 5-in. grate 6'A-in. grate no grate
Gondard mill:
Machine capacity (tons/hr) 8.4 9.0 9.4 —
Power consumption 14.5 11.9 10.3 —
(kw-hr/ton)
Hammer life (tons) 1,200 1,300 1,450
Tollemache mill:
Machine capacity (tons/hr) — — — 15.0
Power consumption — --- — 7.0
(kw-hr/ton)
Approximate hammer life — — — 1,500
(tons)
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These factors and other approximations have been used to
make the cost projections below. The projections are made
for new plants, based on the experience gained at the city
of Madison pilot plant with the Tollemache Mill. The major
assumptions are;
1. The plant is located at the landfill site.
2. One man can monitor two mills.
3. Generally, transfer trailers will be used to haul milled
refuse to the fill site, but packer trucks will be used for a
one-mill installation.
4. Refuse will be accepted from all sources. Thus a separate
landfill compaction machine will be provided in addition to the
front-end loader used in the plant.
5. Each Tollemache mill has a capacity of 15 tons per hr.
6. The mills will be operated 7 hr per shift, 245 days per
year.
7. The milled refuse will be covered with dirt only when the
landfill is filled to the final elevation.
8. Land costs are excluded.
The projected unit costs for new facilities range from $3.02
per ton for one mill operated on a one-shift basis to $1.31 per ton
for four mills operated for two work shifts (Table 8).
LANDFILL CONSTRUCTION USING MILLED
REFUSE WITHOUT COVER
In recent years, there has been a major emphasis on the
elimination of open dumping (often associated with open burning)
in favor of the sanitary landfill. This trend recognizes that the
level of operation achieved in a true sanitary landfill is sufficient
to protect natural resources and avoid insult to citizens and the
environment.
The essential ingredients of any sanitary landfill are that
(a) the entire system is engineered with respect to site selection,
operation, and final use; (b) refuse placed in the site is com-
pacted to reduce its volume and to enhance utilization of the
completed landfill; and (c) a layer of compacted earth is used to
cover the accumulation of refuse at least once a day. Since
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TABLES
ANNUAL COST AND PRODUCTION OF FACILITIES,
BY NUMBER OF SHIFTS AND MILLS
Number of mills
Item
One-shift operation:
Tons milled per day
Plant operating cost
Depreciation
Total operating cost
Landfill operating cost
Depreciation
Total annual operating cost
Tons milled per year
Cost per ton
Two-shift operation:
Tons milled per day
Plant operating cost
Depreciation
Total operating cost
Landfill operating cost
Depreciation
Total annual operating cost
Tons milled per year
Cost per ton
1
105
$40,500
21,600
62,100
13,200
2,300
77,600
25,700
3.02
210
76,000
24,300
100,300
15,200
3,500
119,000
51,400
2.31
2
210
$59,500
38,000
97,500
15,900
4,300
117,700
51,400
2.29
420
114,700
41,300
156,000
14,500
4,300
174.800
102,800
1.70
3
315
$72,200
50,900
123,100
15,900
4,300
143,300
77,100
1.86
630
139,200
55,900
195,100
15,300
4,300
214,700
154,200
1.39
4
420
$91,900
64,200
156,100
15,900
4,300
176,300
102,800
1.71
840
178,100
70,400
248,500
16,100
4,300
268,900
205,600
1.31
omitting the daily cover would depart significantly from the
established method, it was considered necessary to examine the
factors that make a sanitary landfill acceptable and to consider
use of uncovered, milled refuse with respect to each of these
factors.
The requirement that a sanitary landfill be engineered with re-
spect to site selection and utilization will not be given further
attention here, for skilled engineering design is necessary whether
the landfill is a traditional sanitary landfill or one constructed with
milled refuse. Some of the design considerations may change
according to factors outlined below; however, excellence of
design is a prerequisite to either type of operation.
First of all, compaction is required in a sanitary landfill
to reduce voids that may harbor rodents or abet fires, and to
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provide the most efficient use of space. Compaction also improves
the usefulness of the completed landfill by providing more uniform
settling and a reduced change in volume from that first observed
after site completion to that reached after degradation is complete.
Even though compaction of milled refuse would be practiced,
the departure from the usual sanitary landfill to a milled refuse
landfill without cover was examined carefully with respect to
in-place refuse densities and settlement.
Evaluation Procedures
The acceptability of not providing daily cover for milled
refuse was evaluated with respect to each of the reasons cited
for the use of daily cover as well as to general operating charac-
teristics of such a landfill. Field evaluations were done at
the city of Madison's Olin Avenue Landfill, adjacent to the milling
facilities. This area is about 60 acres in size and is actually
an old open dump that filled a marsh. The area was leveled,
covered with some 2 ft of soil, and deactivated as an open
dump in the early 1960's. The water table is typically 1 to 2 ft
beneath the surface.
To provide a direct comparison between the milled refuse
without cover and the sanitary landfill technique, refuse was
placed in piles called cells. The cells were 5 to 6 ft in height
and were level. Lengths and widths varied, but the smallest
cell was at least 40 ft in its shortest dimension. Cell construc-
tion was scheduled so that both covered, unmilled cells and milled,
uncovered cells were constructed simultaneously, allowing for
ready comparison. Cells were typified by the season of the year
during which they were constructed, their age, and, in the case
of milled cells, the grate size used in the mill. Both cell types
were compacted with a D-7 caterpillar tractor, and in the case
of covered cells, the cover soil was a sandy-silt obtained from
a site 5 miles away. Six in. of soil were used for all covered
cells.
It should be noted at this point that, strictly speaking, those
cells constructed with unmilled refuse and covered were not
sanitary landfills. Insufficient refuse was available to construct
an entire cell, or even a major portion of a cell, in a single
day. A choice had to be made, therefore, between covering the
small amount of refuse placed daily, covering all exposed refuse
daily except for the working face, or covering each cell upon
its completion. It was felt necessary to avoid the atypical situation
of having cells consisting of small pockets of refuse bounded by
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soil and the attendant difficulties in understanding and tracing
moisture and gas movement in such a situation. Furthermore,
it would be poor practice to leave an entire cell uncovered
until its completion. The decision was, therefore, to leave only
the working face exposed at the close of each day's operation.
The difference between a cell covered in this fashion and a true
sanitary landfill (which is covered daily) is felt to be insignificant
with respect to the results of this study.
In addition to the landfill observations, some special tests
were run at other locations. These tests will be described
later in the presentation.
Specific Test Procedures, Results, and Discussion
Each of the many aspects of the landfill evaluation program
will be considered on a point-by-point basis, with a presentation
of the test procedures and a discussion of the results for each
one. All of those areas of concern mentioned previously will
be considered, as well as general operational characteristics of
milled, uncovered daily landfills.
Esthetics. Milled refuse was found to look like shredded paper
to the nearby viewer. As one moves away from the refuse, it
rapidly begins to look nondescript. Perhaps the most valid basis
for this statement is that of all the thousands of people who have
viewed the landfill, no one has objected to the sight of milled
refuse that was not covered. A typical first reaction is one of
surprise that refuse can look so unobnoxious.
Odors. The Olin Avenue Landfill is within the city of Madison,
bounded by a playfield on one side, residential areas on two sides,
and the Dane County Coliseum and County Fairgrounds on the
other. The Coliseum is a new 10,000-seat facility for sporting
events, concerts, and other performances playing to large audi-
ences. There was some apprehension when the project was first
formulated that the location of the test landfill would invite com-
plaints if the slightest odors were produced.
No odor problems have developed, however. Experience has
indicated that visitors are surprised at this and usually ask why
there is essentially no odor. Project personnel believe that the
unusually free access of air to the refuse cells and the rapid
drying out of the surface of the cells provides an aerobic buffer
zone that removes or reacts with potential odor-forming substances
formed within the cells. In support of this theory, it was noted
that by digging 3 to 6 in. into a cell, one begins to detect an odor
typical of decaying refuse. On digging a foot or more, a most
disagreeable odor is produced.
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Some relatively minor odor problems were detected during
unusually wet periods when, because of improper drainage of the
depressions between the test cells, ponds of water were formed.
These problems were readily overcome by filling in such areas
or by providing drainage.
Blowing Paper. Blowing paper is one of the problems most
frequently cited by sanitary landfill operators or administrators.
The city of Madison is no exception. In spite of 6-ft fences around
its Mineral Point and Truax Field Sanitary Landfills and the use
of 15-ft movable fences placed downwind from the working face,
blowing paper continues to be a problem. In 1969, some $22,000
was spent for manpower to pick up this blowing paper in a sincere
attempt to reduce complaints.
The city is so pleased with the lack of blowing, milled refuse
that the director of public works has stated that he would be willing
to use the milled refuse system for this reason alone. There have
been essentially no blowing problems with milled refuse, even
though operations have been continued at winds up to 60 mph on
a flat landfill.
There are two reasons for the lack of blowing. First, milled
refuse particles tend to become intertwined so that they are
discharged as a group rather than as individual particles that can
be blown away. Second, if one drops a page from a newspaper and
a 2-by 2-in. piece of newspaper simultaneously in a strong wind,
the small piece will blow a few feet and come to rest, but the full
page will blow long distances. As milled refuse is ejected from
the transfer vehicle it is observed to blow a few feet in a strong
wind, but that is all.
Fires. In August 1969, the city of Madison fire department
carried out an evaluation of any fire hazard arising from the lack
of cover on milled refuse. Tests were run both on refuse that
had been placed within a month of the test date and on refuse
placed at least 1 year before the test. The temperatures during
the test period were generally in the low 70's, relative humidity
near 70 percent, and wind velocities were 2 to 6 mph. The
moisture levels of the refuse cells would be expected to be
less than average, arising from less than average rainfall for
the preceding month.
The fire department undertook tests in which milled refuse
cells without cover were ignited by several methods chosen to
simulate potential fire sources in actual landfill situations.
In summary, it was observed that the aged, milled refuse
would not support a flame, nor would it propagate combustion in the
sense that the area of combustion would continually expand with
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time. The refuse would smolder on the surface and was readily
extinguished with water. Freshly milled refuse will also burn
at the exposed surface but will only smolder and not produce a
flame. A major difference between aged and freshly milled refuse
was that the area of combustion in the latter case would grow,
eventually encompassing the entire cell surface. Again, however,
the rate of propagation was slow, and combustion was limited to
the cell surface, where it could be extinguished with water.
Vectors. A rather extensive description of all the vector studies
has been published in the January-February 1971 issue of
Compost Science, and earlier articles in Public Works (July,
1969 and June, 1970) presented in more detail certain portions of
the vector studies. Only a summary of the vector studies is
presented here.
The portion of the vector work dealing with rats is divided into
three parts: first, to determine whether rats are more likely to
be found near milled refuse without cover or covered refuse that
was unmilled; second, to determine if milled refuse without
cover will draw a rat population; and third, to determine if rats
can survive on milled refuse.
The first portion of the rat studies involved placing bait stations
at many locations within the Olin Avenue Landfill and observing
the rate of bait consumption. This evidence, plus observations
of burrows, the apparent activity of the burrows, and actual rat
sightings were used as an indication of where the rats were located
at the landfill, and whether they preferred milled, covered
refuse cells, or covered, unmilled refuse cells.
The conclusions of this portion of the study were, first, that
the rats had a definite preference for locations near the periphery
of the landfill, especially the border closest to a nearby creek.
This preference overshadowed any preference for either the milled
or unmilled cells. Second, most of the burrows were found on
covered cells containing refuse that was unmilled. Although there
was much test drilling on milled refuse cells, few burrows were
developed, probably because of the lack of food materials of
sufficient size and the difficulty in making a stable burrow in
the milled refuse. In this regard, it was noted that most burrow
development occurred when there was a surface irregularity on
a cell, such as an erosion gully or the protrusion of a large object.
Both of these situations were less likely to occur with the milled
refuse cells.
In two instances, milled, uncovered refuse wasplacedin remote
locations to determine whether rat activity would be drawn to it.
In the first case, the refuse was placed in an open space within
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a residential area where no rats were positively known to exist.
In the second case, refuse was placed in a remote, unused spot
in the Olin Avenue Landfill where rats were known to exist at
the time. When no evidence of rat activity could be found on either
test pile after several months, the test was terminated.
The final portion of the rat studies involved feeding milled
refuse to rats to determine whether they can survive on refuse
and water. This portion of the work was contracted to Purdue
University, where a large colony of wild Norway rats is kept
for test purposes. On four occasions, groups of 10 rats were
placed in cages containing only water, refuse and nesting facilities.
Sufficient milled refuse from Madison was placed in the cages to
insure that at least two to four times the amount of food matter
required by rats was present at all times. In two tests, freshly
milled refuse was used; in two other tests, refuse milled two
years before was dug from an Olin Avenue Landfill cell. The
conclusions were that the rats could not survive on either aged
or freshly milled refuse, for after 6 to 12 days, they resorted to
cannibalism to survive.
The fly studies were also divided into several parts. The first
part was to indicate whether milled, uncovered refuse was more
or less preferable to flies than unmilled, covered refuse. The
second part of the study was to compare fly emergence on milled
and unmilled refuse. The third section was to determine whether
flies can survive and complete their life cycle in milled refuse
under laboratory conditions, and the fourth was to determine the
mortality rate of maggots passed through the milling process with
municipally collected refuse.
A Scudder Grille was used to determine fly population densities
at the Olin Avenue Landfill. The grille looks much like a miniature
wooden fence, consisted of 1/4-in. by 3/4-in. slats arranged in
such a fashion that flies would be drawn to it because of the
many edges. The grille was placed on each test spot, and the
flies present after 30 seconds were counted. If this procedure is
done under specified, uniform weather conditions, it is a standard
means of evaluating fly populations in the immediate vicinity of
a test area.
The Scudder Grille was used to evaluate the relative numbers
of flies on the several types of test refuse cells at the Olin
Avenue site. In particular, the densities of the fly populations on
the milled, uncovered cells were to be related to the densities
on the unmilled, covered cells. The conclusion was that there was
little difference between the two cell types with respect to fly
populations to be found on them. The results suggest that slightly
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fewer flies were found on the milled cells, but that the differences
as well as the fly populations in each case were small.
The second portion of the fly studies dealt with the likelihood
of flies emerging from milled and unmilled piles of refuse.
Approximately 2 tons of refuse were placed in each of three
screened enclosures measuring 10 by 10 by 6 ft high. Milled
refuse was placed in two of the enclosures, and unmilled refuse
that had been compacted with a D-7 tractor was placed in the
third. No cover was used in any case. Periodically during a
1-month period in midsummer, the number of flies in each
cage was estimated. The results indicated that considerably fewer
flies emerged from milled refuse. In addition, of the 3,200 adult
flies and maggots introduced to the one milled refuse cage, the
flies were able to survive but the maggots could not complete
their life cycle.
The final two portions of the fly studies were directed to the
question of why so few flies were observed on milled refuse.
Freshly milled and 6-month-old milled refuse samples were sub-
jected to the optimum temperature, humidity, and light conditions
commonly used to promote fly populations in laboratories to
determine if flies could ever complete their life cycle using milled
refuse as a substrate. Cardboard cartons filled with milled refuse
of the desired moisture content were covered with cheesecloth.
To one carton of each refuse type, approximately 1,000 fly
eggs were added; no eggs were added to the other two cartons.
In the carton of freshly milled refuse to which no eggs were added,
no flies were observed; in the carton to which 1,000 eggs were
added, approximately an equal number of flies developed at the
end of the 3-week life cycle. This test result indicates that under
the closely controlled laboratory conditions, freshly milled refuse
can support flies throughout the growth cycle. This ability was
evidently lost within the first 6 months of aging, however, for no
houseflies were observed in either carton containing the aged,
milled refuse.
The final portion of the fly tests examined the survival of
maggots in the milling process itself. Two tests were undertaken
by adding 6.000 and 12,000 maggots, respectively, to about 100
Ib of refuse on the feed conveyor going into the mill. This refuse
was then collected in plastic bags after milling and subjected to
the laboratory conditions shown previously to promote fly emer-
gence with freshly milled refuse. The results were that no adult
flies emerged from the first refuse sample, but 84 did from the
second.
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The conclusions of the try studies point to several reasons
why there have been no fly problems with milled, uncovered refuse
throughout the 4 years of this project. First, the milling process
itself kills nearly 100 percent of the maggots that may be present in
incoming refuse. Second, the optimum conditions necessary for
freshly milled refuse to support the fly reproduction cycle are
rarely obtained in a landfill (moisture content is especially im-
portant). Third, once the refuse has aged a few months, this
ability is destroyed, even under optimum conditions. Fourth, field
studies indicate that whether flies emerge from refuse or else-
where, they will be no more attracted to milled, uncovered refuse
than to covered piles of unmilled refuse.
Leachate and Gas Production. Of the 22 refuse cells built at
the Olin Avenue Landfill, 14 were provided with a mechanism for
leachate collection. This mechanism consisted of a plastic sheet
approximately 40 by 40 ft, placed at the base of each cell and
contoured in such a manner that water flowing onto the sheet was
directed to a reservoir at the center. The reservoirs consisted
of vertical sections of pipe at least 6 in. in diameter, sealed at
the lower end, and protruding above the top of each cell. Appro-
priate slots were cut into each pipe so that leachate would flow
from the plastic sheets into the reservoir, where it could be
pumped out using a vacuum pump.
The leachate accumulated since the previous sampling was
pumped out once every 2 to 4 weeks or more, depending on the
season of the year and the history of each particular cell. The
volume of leachate and its temperature were noted, and samples
were taken for laboratory analyses for conductivity (specific
conductance), pH, alkalinity, hardness, chemical oxygen demand
(COD), chlorides and sometimes nitrogen in its various forms,
phosphorus, biochemical oxygen demand (BOD), dissolved oxygen,
and iron. Records were also kept of weather station precipita-
tion data for use in interpreting leachate volume results.
Gases were sampled from various locations with 12 of the refuse
cells by means of rubber tubes connected to plastic funnels im-
bedded in the cells at 1-, 3-, and5-ft depths. The open ends of the
funnels were covered with coarse screen to prevent blockage.
The sampling process consisted of withdrawing gas through the
rubber tubes and into 125-ml gas sampling flasks, using a vacuum
pump. The assembly was purged for 30 seconds before the valves
on either side of the sampling flasks were closed to isolate
the sample. Analyses were performed using a Fisher Gas
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Partitiorer to determine concentrations of H2, N2, O2, CO2,
and CH4. It is noted that this device does not measure water
content. A special effort to measure NH3 was unsuccessful be-
cause of very low concentrations. Gas sampling normally was
done monthly.
The data indicate that the milled cell produced leachate more
rapidly and at a higher rate than did the cell with unmilled refuse.
It is likely that the flat surface of very absorptive, milled refuse
readily soaked up moisture rather than passing it off as runoff,
thus accounting for the more rapid leachate production. Once
the cell with unmilled refuse had picked up sufficient moisture
to reach field capacity, however, it produced leachate at approxi-
mately the same rate as did the milled cell.
As refuse reaches field capacity and begins to produce leachate
regularly, complex reactions take place as it undergoes the process
of decomposition. Biological activity becomes increasingly im-
portant as moisture levels above a threshold level are reached;
and as a result of biological action, previously solid organic
matter is rinsed out by water flowing through the refuse. This
leached organic matter is measured by the COD test in terms of
the oxygen equivalent required to chemically oxidize it in a
strongly oxidizing solution.
The milled cell rapidly produced leachate with a peak COD
value, and the peak occurred soon after leachate was produced
regularly. This fact is in keeping with the observation that the
milled cell accepted moisture more rapidly, produced leachate
more quickly, and therefore reached moisture levels more suitable
for decomposition sooner than did the unmilled, covered cell.
The COD value began a steady decline after this peak and exhibited
minor rises during subsequent summers as summer weather
warmed the cells and promoted slight COD increases.
The cells of covered, unmilled refuse exhibited much different
COD curves. COD values of these cells increased to an initial
peak value after a longer waiting period than with the milled cell.
The peak is relatively low at 20,000 ppm. This initial COD peak
represents removal of only a fraction of the total COD to be pro-
duced, however, and it is left for continued activity during subse-
quent warm summer months to remove the remaining COD. It
is not possible to conclude from these results which type of
degradation curve is better for the environment. Whether one curve
is more desirable than the other is a matter of judgment. But
for a landfill in use over a period of several years, approximately
the same amount of COD will be produced regardless of which
curve is applicable.
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65
Conductivity is similar to COD in that both are gross indi-
cators of the amount of certain classes of material in leachate.
COD is primarily a measure of organic content. Conductivity is
mainly a measure of the ionic content, which is in turn a measure
of the dissolved inorganic matter in the leachate. The solubility
of inorganic matter is a function of several factors that are
related to the level of biological activity, including temperature,
pH, and direct biological action. It is not surprising, therefore,
that the conductivity curves are somewhat similar to the respective
COD curves. As with the COD values, a peak conductivity value
was produced more quickly with the milled refuse cells. The
conductivity of the leachate from the milled refuse cell also dropped
off to a continued but lower value rather quickly after the peak
value was reached; with the unmilled, covered cell, conductivity
values have continued at higher levels through the later years of
study.
It is beyond the scope of this article to consider the results
of the other leachate analyses, including alkalinity, hardness,
chloride, iron, nitrogen, and phosphorus. The results of these
analyses are useful in attempting to understand the decomposi-
tion process in more detail, and they do provide some insight
into the pollution potential of landfill practices. It is simply
noted here that the curves of these parameters fit in well with
the COD and conductivity results and the discussion of these
results given previously. Typical concentrations of these param-
eters are provided in Table 9.
The gas composition results were not nearly as informative
as those on leachate in describing the decomposition and the
environmental effects of the two cell types. The data for dif-
ferent cells of the same type, which would normally be expected
to correlate, varied so widely that it was difficult to describe
typical curves to determine the real differences between milled,
uncovered and unmilled, covered cells. Part of this variability
is evidently inherent in gas sampling, since even the results
for one specific cell often fluctuated widely from one sampling
period to the next.
There are several reasons for the variability in the gas results.
First, gas samples represent the gas composition at the point
and time of sampling, whereas leachate samples represent
averages over large portions of the cells and from the previous
sampling date. Second, a given sampling location may be highly
unrepresentative of the entire cell, for refuse composition
or moisture routing through the cell may be atypical at that
point. Third, cracks or other ready access to the cell surface
-------
66
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