PB-214960
Baling Solid Waste to Conserve
Sanitary Landfill Space
a feasibility study
San Diego City, California
prepared for
Environmental Protection Agency
Office of Solid Waste Management Programs
1973
Distributed By:
National Technical Information Service
U. S. DEPARTMENT OF COMMERCE
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BIBLIOGRAPHIC DATA 11- Report No.
SHEET I -~^ EPA-SW-44D-73
4. Title and Subtitle
Baling Solid Waste to Conserve Sanitary Landfill Space;
a Feasibility Study
3. Recipient's Accession No.
^§214-960
5' Report Date
1973
6.
7. Author(s)
City of San Diego
8. Performing Organization Kept.
No.
9. Performing Organization Name and Address
City of San Diego
San Diego, California 92101
10. Project/Task/Work Unit No.
11. JpJttKSeX/Gram No.
G06-EC-00061
12. Sponsoring Organization Name and Address
U.S. Environmental Protection Agency
Office of Solid Waste Management Programs
Washington, D.C. 20460
13. Type of Report & Period
Covered
Final
14.
15. Supplementary Notes
16. Abstracts ,
•In addition to the purpose indicated by the title, the study was also designed to:
(1) explore the possibilities of reducing direct haul distances; (2) study the use
of solid waste bales as fill in reclaiming small canyons near residential areas;
(3) compare the compaction obtained by baling with that achieved through conventional
methods; (4) investigate baling as an integral feature of possible transfer station
operations; (5) develop yardsticks, formulas, and techniques that might be useful to
other communities in dealing with their solid waste collection and disposal problems./
17. Key Words and Document Analysis. 17a. Descriptors
*Waste disposal, Urban areas, *Baling, Compacting
17b. Identifiers/Open-Ended Terms
*Solid waste disposal, solid waste transfer stations
17c. COSATI Field/Group
13B
18. Availability Statement
Release to public
<=-ORM NTIS-3S (REV. 3-72)
19.. Security Class (This
Report)
UNCLASSIFIED
20. Security Class (This
Page
UNCLASSIFIED
21. No. of Paxes
22. .Price
USCOMM-DC I4952-P72
\- CL/
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EPA-SW-MD-73
BALING SOLID WASTE TO CONSERVE SANITARY LANDFILL SPACE
A Feasibility Study
This publication (SW-44d) reports on work performed under
Federal solid waste management demonstration grant no. G06-EC-00061
to the CITY OF SAN DIEGO, CALIFORNIA,
and is reproduced as received from the grantee.
U.S. ENVIRONMENTAL PROTECTION AGENCY
1973
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This report has been reviewed by the U.S. Environmental
Protection Agency and approved for publication. Approval
does not signify that the contents necessarily reflect
the views and policies of the U.S. Environmental Protection
Agency, nor does mention of commercial products constitute
endorsement or recommendation for use by the U.S. Government,
An environmental protection publication (SW-44d) in the
solid waste management series.
111
Preceding page blank
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PREFACE
Conserving sanitary landfill space and minimizing transport costs are two
important objectives in the processing of solid waste materials. Processing--
changing solid wastes in some fashion—may mean converting the wastes into a
more stable form or into a different physical state by chemical, thermal, or
biological means. Or it may mean mechanical alteration such as by size
reduction and densification. Baling solid wastes, the subject of this report,
is an example of the latter kind of processing.
The investigation performed by the City of San Diego, California, and
described in this document has contributed significantly to advancing the
state of the art in the solid waste processing field. This report, plus the
recently published results of a Federal grant to the City of Chicago entitled
High-Pressure Compaction and Baling of Solid Waste (SW-32d), constitute prime
literature presently available on the subject of baling solid wastes.
In the present study the feasibility of baling solid wastes.is examined
to see if the technique could significantly prolong the life of both existing
and future sanitary landfills. The effectiveness of solid waste baling
under two circumstances is evaluated: (1) using unshredded solid waste at
a local baling site; (2) using shredded solid waste baled offsite at a
commercial facility. The densities achieved are compared to those obtained
using conventional sanitary landfill techniques. In addition, the possi-
bilities of using a baler transfer station are explored.
As a follow-up to this study a pilot baling plant is currently in
operation in San Diego with the support of a solid waste demonstration
grant from the U.S. Environmental Protection Agency (EPA). The facility
has been active since the summer of 1971 and is presently processing
approximately 100 tons of solid waste per day. A final report covering
the operation of the pilot plant and evaluation of the complete baling-
transport-disposal system is scheduled for completion in late 1973 and
subsequent publication.
Eric Quartly served as Project Director for the City of San Diego
while David Arella and Keith Grems served as EPA project engineers for the
completed project reported herein.
—JOHN T. TALTY, Director
Processing and Disposal Division
IV
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TABLE OF CONTENTS
Chapter
II Summary and Conclusions
Abstract ix
Introduction 1
Nature of the Project ..... 1
Methods of Procedure 2
Evaluation of the Progress of the Project 3
Definition of Terms Used in the Report 3
General Description of the City 3
Brief History of Refuse Operations in San Diego .... 4
Summary of the Report 7
Recapitulation of Conclusions 9
III Physical Feasibility of Baling Refuse 11
The Baling Process 11
The Baling of Refuse 13
Local Refuse Baling Tests ..... 13
Manufacturer's Refuse Baling Demonstration . . * . . . 23
Comparison of the Local and Factory Tests 30
Summary of the Chapter 37
IV Economic Feasibility of Baler Transfer Stations ...... 38
Conventional Transfer Stations 38
The Proposed Pilot Baling Transfer Station 41
Cost of the Proposed Pilot Station 46
Conventional versus Baling Transfer Stations 46
Transfer Station Location 49
Basis for the Economic Feasibility Study 54
Data for Direct Haul Cost Study 54
The Economics of Direct Haul 58
Comparative Costs of Conventional and Baling
Transfer Stations 61
Cost Comparisons ...... 61
Summary of the Chapter 65
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TABLE OF CONTENTS (Continued)
Chapter
V A Look Ahead 66
The Proposed Demonstration Project 66
Objectives of the Project 67
Method of Procedure 67
Evaluating the Project ....... 68
Areas of Special Interest 69
Factors Contributing to Bale Compaction • • • 69
Limiting the Pilot Plant to City-collected Refuse ... 70
Reclamation of Small Canyons 71
Summary of the Chapter 73
Appendix
1. Comparison of San Diego with Six Selected Citias . . 75
2. Letter of Inquiry and Mailing List of Baler
Manufacturers 76-79
3. Notes on Manufacturer's Demonstration of Refuse
Baling 80
4. Mathematics of Direct Haul Costs ......... 84
5. Cost of Pre-shredding Municipal Refuse 86
Bibliography ..... 88
vi
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LIST OF TABLES
Number Page
1 Summary of Local Baling Test Results 19
2 Summary of Ratings of Bale Characteristics, Local
Baling Test 22
3 Estimated Capital Expenditures for Pilot Baling
Transfer Station 47
4 Estimated Current Operating Expenses of Pilot Baling
Transfer Station for One Year 48
5 Factors for Consideration in Location of Transfer
Stations 50
6 Weekly Round Trip Mileage Increase, Direct Haul to
Murphy-Shepherd Landfill versus Arizona Landfill .... 57
7 Estimated Annual Costs of a Full-scale Conventional
Transfer Station 62
8 Estimated Annual Costs of a Full-scale Baling Transfer
Station 63
9 Annual Savings in Disposal Costs .. 64
10 Comparative Annual Costs of Conventional and Baling
Transfer Stations 64
vii
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LIST OF FIGURES
Number
1-4 Design and Operation of the Local Test Facility , . .' . . . 15-18
5 Weights, Volumes, and Densities of Bales
Produced in Local Baling Test ...... 20
6-9 Views of Local Bale Disposal Experiment 24-27
10-11 Factory Refuse Baling Demonstration 28-29
12-13 Comparison of Raw Materials, Local and
Factory Tests . 32-33
14-15 Comparison of the Finished Product 34-35
16 Baling Pressure versus Bale Density 36
17 Views of a Conventional Transfer Station 40
18 Pilot Baling Transfer Station 43
19-20 Elevations of Pilot Baling Station 44-45
21 Three Views of a Small Canyon 51
22 View of Proposed Baling Transfer Station Site 53
viii
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ABSTRACT
Project
Study and Investigation
Title
Investigate and Evaluate Feasibility of Refuse Baling as a Means
of Conserving Sanitary Fill Space
Objectives
To investigate and analyze the physical and technical feasibility
of baling municipal refuse and the economic feasibility of using
this process in combination with the transfer station concept.
Procedures
Municipal refuse was actually baled in a local test program and in
a demonstration by a baler manufacturer. Compaction thus obtained
was compared with that obtained by present landfill methods. A
preliminary design for a proposed pilot baling transfer station
was prepared. Comparative costs were estimated for (l) longer
direct haul to a more remote fill, (2) full-scale conventional
transfer station operation, and (3) full-scale baling transfer sta-
tion operation.
Findings
The process of baling municipal refuse is physically and technically
feasible with presently available equipment and economically feasi-
ble when combined with the transfer station concept. Greater compac-
tion can be achieved by baling than by the use of standard compaction
methods (bulldozer or compactor) in sanitary landfills. Under
certain frequently met conditions, baling transfer stations are more
economical than longer direct hauls by collection vehicles. In the
station capacity ranges studied, baling transfer stations are more
economical than conventional transfer stations. Construction of a
pilot baling station is recommended in order to test the findings
and tentative conclusions of this study and investigation project.
ix
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CHAPTER I
INTRO D U C T I 0 N
Increasing national concern about the serious and urgent problem of solid
waste disposal is shared by the citizens of San Diego and by their municipal
government. This concern has been the principal motivation for the city's
undertaking, in cooperation with the United States Public Health Service,* the
project described in this report..
San Diego has its own unique problems to face in this field aud its own
special complex of available resources to solve them. Although the project
has been primarily oriented toward these local considerations, an important
secondary motivation has been the hope that this city's investigations and
findings may be helpful to other municipalities confronted by similar refuse
disposal problems.
Nature of the Project
This study and investigation project, entitled "Investigate and Evaluate
Feasibility of Refuse Baling as a Means of Conserving Sanitary Fill Space,"
was jointly financed by city funds and a grant from the Solid Wastes Program
of the Public Health Service's National Center for Urban and Industrial
Health. It represents the first year of a possible three-year project in
which the initial study and investigation phase would be followed by a demon-
stration phase involving the construction and operation of a pilot baling
transfer station.
The purposes of the first phase, reported herein, were not only (as the title
indicates) to determine the feasibility of refuse baling as a means of con-
serving the life of sanitary fill sites but also (l) to explore the possibili-
ties of reducing direct haul distances, (2) to study the utilization of refuse
bales as fill in the reclamation of small canyons in close proximity to
residential areas, (3) to compare compaction obtainable by baling with that
obtained by conventional methods, (U) to investigate baling as an integral
feature of possible transfer station operation, and (5) to develop yardsticks,
formulas, and techniques that may be useful to other communities in dealing
with refuse collection and disposal problems.
Locally the project received direction and leadership from the Public Works
Director of the City of San Diego and was coordinated by the Senior Adminis-
trative Analyst of the Public Works Department. The full-time staff consisted
of an Associate Civil Engineer (borrowed from the Engineering Department for
the duration of the project) and, assisting him, an Administrative Analyst and
an Administrative Trainee. Other professional members of the Engineering and
Public Works Departments served part-time as consultants and resource people.
Clerical workers, equipment operators, and laborers were provided either on a
scheduled part-time basis or for temporary periods as required by the progress
of the work.
*Federal responsibility for this project now lies with the U.S. Environ-
mental Protection Agency.
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In a real sense, the city's Chollas Sanitary Landfill served as a practical
laboratory for certain phases of the project - notably (l) an extensive study
of refuse compaction by conventional methods based in part on sampling of the
extent of refuse dumping at the fill by private contractors and citizens and
(2) actual testing of refuse baling using a local baler leased for this pur-
pose .
Methods of Procedure
In its investigation of various methods of refuse baling, the staff sent
inquiries to a total of fifty baler manufacturers throughout the country to
learn the types, characteristics, and capabilities of equipment available for
or adaptable to the baling of refuse. Replies were received from twenty-five
companies.
It was found that only a few firms manufacture equipment that can be readily
adapted to the baling of municipal refuse. Still fewer have actually done
research and.development work leading toward the production of such equipment
or the adaptation of existing models to this purpose. There is evidence, how-
ever, of increasing awareness on the part of manufacturers that there may be
a potential market for balers specifically designed to process solid wastes.
The special problems of baling municipal refuse economically on a large scale
and the cooperative efforts,that have been made by the City of San Diego and
an interested baler manufacturer to solve those problems are discussed in
Chapter III of this report.
The project staff also canvassed twenty-two local business firms to determine
the types of balers being used commercially in this city and to locate balers
that might be available and suitable for the initial testing of refuse baling.
This search resulted in the city's finding and leasing a balar which,although
it had relatively low compression capability as compared with modern, heavy-
duty equipment, could be used for testing purposes on a systematic basis. A
substantial number of bales were produced, their densities were calculated,
and such characteristics as shape, ease of handling, and absence of odor were
evaluated. A number of completed bales were stacked or "nested" in a simu-
lated landfill situation in order to investigate the best equipment and
procedures for this purpose and to discover the kinds of problems that might
arise in the process. A description of these experiments and their results
will also be found in Chapter III.
Both of these approaches--cooperation with a baler manufacturer and the local
testing experiment—were found to be valuable in (l) exploration of the com-
paction potentialities and the technical feasibility of baling municipal
refuse and (2) preliminary evaluation of various types of available baling
and auxiliary equipment to determine which is most suitable for1use in a
possible pilot operation.
In order to evaluate the economic feasibility of refuse baling, the staff con-
ducted sampling, engineering, and statistical studies of compaction obtained
by present sanitary fill techniques and compiled data on costs of present
methods.
These were compared with the estimated costs of possible alternative opera-
tions involving baling. Specifically, evaluations were made of the economics
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of a "baling transfer station as compared with a conventional transfer station
and also with direct haul to the fill site. These studies are presented in
Chapter IV..
Also set forth in Chapter IV are (l) design concepts, preliminary drawings,
specifications, and cost estimates for a prototype baling transfer station,
(2) related equipment and manpower studies, and (3) survey studies to deter-
mine the optimum site location for such a station. -
Evaluation of the P^ogess of the Project
Weekly staff meetings were held throughout the course of the project. These
were attended regularly "by the Project Director and the Project Coordinator
and from time to time by other officials of the Public Works Department, the
Sanitation Division, and the State of California. At these sessions the prog-
ress of the work was appraised, problems were discussed, and subsequent steps
were planned. Detailed written progress reports were submitted to the Project
Director once a week and once a month to the National Center for Urban and
Industrial Health, Public Health Service. The Project Officer for the National
Center made several trips to San Diego to discuss concepts and project plans
and to review progress of the study.
Definitions of Terms Used in the Report
In general any technical terminology used in this report follows the usage and
definitions of standard reference works in the literature of the field, par-
ticularly Refuse Collection Practice and Municipal Refuse Disposal prepared by
the American Public Works Association with the assistance of the United States
Public Health Service and published by the Public Administration Service.
Terms that do not appear in these sources, or that are peculiar to San Diego,
are defined as they appear in the context of the report.
General Description of the City
San Diego is a coastal southern California city of 69^,000 population, third
largest in the state and, according to the United States Bureau of the Census,
eighteenth largest in the nation. It has experienced a rapid rate of growth
in recent decades and this trend is expected to continue for the foreseeable
future. It is not heavily industrialized. In 1960 it had, for each 100,000
people, only nineteen manufacturing establishments of twenty or more employees
each as compared with 95 in Cincinnati and 63 in Seattle! Its central retail
business area is comparable with that of other American cities of its size,
and smaller shopping centers are scattered throughout the city. An extensive
Naval establishment is clustered in and around its excellent harbor, and a
large Naval air station is located in the northern section of the city. These
installations together with Marine facilities in the city and its metropolitan
area combine to give San Diego a strong military flavor.
See Appendix 1 for a comparison of San Diego with six selected cities of
comparable size, with respect to population, housing, industry, and climate.
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The city's subtropical climate, natural points of interest, and varied rec-
reational facilities attract large numbers of tourists and other visitors,
particularly but by no means exclusively during the summer months. Perhaps
for the same reasons there is a considerable segment of retired persons in the
population.
Transient or relatively transient visitors to the city are a significant fac-
tor in shaping the special character of San Diego's refuse problem. The daily
average number of visitors in the city is more than 85,000. According to a
recent study by the local Economic Research Department of Copley Press, Inc.,
"the visitor industry is San Diego's third largest source of basic income. It
ranks ahead of agriculture and behind manufacturing and Navy payrolls as a
source of new money for San Diego." Military personnel living on board ships,
in barracks, or, often with dependents, in housing units at major military
installations numbered about 60,000 in 196?- These more or less temporary
residents, together with such smaller groups as college students living in
dormitories, patients at hospitals, and institutional inmates or prisoners,
total approximately 150,000 - in themselves the equivalent of a good-sized
city - and while they are here they produce a substantial quantity of refuse.
Spread over an area of 310 square miles, San Diego has a population density
of 2,180 persons to the square mile. In 1960 this density was 2,944 (the
decrease since then is due to the annexation of additional outlying areas to
the city), as compared with 15,157 in Boston and 3,966 in San Antonio. The
city's Planning Department reported in October, 1967, that only 38 per cent
of San Diego's land area is urbanized (this is the portion, incidentally, in
which the city has established refuse collection routes), "with most of the
remaining land devoted to agriculture and open livestock grazing." The
Department went on to say that within the city limits "there are large acre-
ages of completely vacant or unused land, much of it in steeply sloping hill-
sides and canyons." Even in those areas where there has been urbanized
development the terrain is intersected by numerous canyons and there is,
therefore, more than the usual proportion of dead-end streets.
Seventy per cent of the city's 215,000 housing units are single family dwell-
ings. In 1960 this percentage was 71 as compared with 16 per cent in Boston
and 56 per cent in Pittsburgh.
Brief History of Refuse Operation in San Diego
The year 1919 marked the first assumption by the city of responsibility for
the solid waste problem in an organized way. At that time the Sanitation
Division was created and took over the task of collecting refuse, which had
previously been either burned on the householder's premises or hauled away by
private contractors. Some of the policies initiated then have remained
largely unchanged to the present day. The Sanitation Division has never had-
a major reorganization, although it was decentralized to a degree in 1952
when, due to growth of the city, its work could no longer be handled from a
single operations station. Both the early-morning collection "sweep" through
the downtown business area by a fleet of vehicles and the "daily route method"
of collection in residential areas, in which a specific area is assigned to
each crew each' day, have been used throughout the intervening period. The
Division has been greatly expanded in personnel, facilities, and budget over
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.the years and many technical improvements have been introduced, but the basic
principles of administrative organization and of scheduling collection that
were found to be successful in the beginning are believed to be still valid
today.
The physical and mechanical changes in sanitation service techniques that
have been most apparent to the average citizen have been in the kinds of col-
lection vehicles used. There has been a progressive adoption of improved
transportation equipment, as it became available, for more efficient perform-
ance, more attractive appearance, and better protection of the public health.
Horse-drawn wagons were replaced by motorized open-box trucks in 1926 and in
turn by enclosed packer trucks in 1946. These were the cylindrical, side-
loading type until 1955 when they were replaced by the box type with rear-
loading hoppers. In 1965 the city began a transition from twenty-yard packer
trucks with three-man crews to twenty-five yarders with two-man crews. This
change is still in progress.
Until 1958 garbage was collected separately twice a week and sold to hog
farms. Since that date it has been integrated with other refuse and collected
once a week in residential areas. A requirement has been in effect since 1924
that garbage and, later, all refuse to be collected must be set out at the
curb or (in sections of the city where they exist) in alleys.
Refuse other than garbage was disposed of by open burning at various dumps in
the city before 1951 when the present "fill, compact, and cover" method was
adopted. The Chollas sanitary landfill in the southeastern part of the city
was opened in that year and is still in use. The other two existing facili-
ties, Arizona landfill in the central section and Miramar landfill on the
north side, were opened in 1952 and 1959 respectively. In the meantime the
Mission Bay Fill was in operation from 1952 through 1959.
By 1958, when it was integrated with other refuse, garbage had become so small
a proportion of the total bulk of solid waste materials that it posed no
serious problems at the landfills except at the Miramar location. Since this
facility is adjacent to the Naval Air Station, sea gulls attracted by the gar-
bage constituted a hazard to aircraft and have had to be systematically
frightened away by the noise of shotgun blasts and by amplifying on a public
address system the recorded cries of gulls in distress. This system has been
highly effective and successful for three years now.
In August, 1966, the city began to use a heavy compactor instead of a bull-
dozer to obtain increased compaction at the Arizona landfill. Aerial surveys
have been utilized in studies of available volume and remaining life expect-
ance of landfills since 1963.
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CHAPTER II
SUMMARY AND CONCLUSIONS
The historical development and present character of the refuse collection and
disposal services provided "by the City of San Diego have been influenced to
some degree by climate and topography. In all essential respects> however,
this operation is comparable with those of many other municipalities. The
findings of this study and investigation project, although based primarily on
San Diego experience and conditions, are believed to have general applica-
bility.
At the present time San Diego is generating more than a half million tons of
refuse a year or about four and one-third pounds a person a day. Rapid popu-
lation growth and gradual increases in the per capita generation of refuse are
expected to double this tonnage by 1985- While this growing demand will in
itself result in higher current expenditures for sanitation service, its im-
pact will be compounded by the exhaustion of existing favorably located land-
fills, the necessity for acquiring new, more remote locations, and accelerated
increases in costs due to longer direct hauls by collection vehicles. This
situation, which is expected to become critical in San Diego within seven
years, has already been or soon will be confronted by many another community.
For these reasons a number of new techniques and procedures that give promise
of mitigating the problem are being explored here and elsewhere under the
solid waste disposal program of the United States Public Health Service. Among
these is the possibility investigated in this project and described in this
report - the baling of refuse. Each of the findings and conclusions arrived
at during the course of the project, summarized in this chapter, is more fully
described and substantiated in the appropriate chapter of the report.
As part of the evaluation of the feasibility of refuse baling as a means of
conserving sanitary landfill space, a major objective of this project, it was
necessary to compare the compaction (l) now being obtained by conventional
landfill methods with (2) that potentially obtainable by baling. The first of
these was investigated by making a field survey at one of the city's landfills
to determine the weight and compacted volume of refuse now being deposited,
and the second by actually baling refuse in controlled test situations.
The tonnage of refuse brought to the landfill by private citizens and commer-
cial contractors is not normally weighed. However, in the field survey, this
tonnage was determined by counting and classifying all private vehicles enter-
ing the landfill during a fourteen-week test period, weighing a 23 per cent
sample during the first six-week's phase of the test, and developing average
weight factors for each vehicle classification. Estimates of private tonnage
thus derived were added to the actual recorded tonnage brought in by city col-
lection trucks. This combined tonnage was compared with the compacted volume
of the materials as determined by aerial volumetric surveys. In three sepa-
rate phases, the study examined differences in densities obtained by using
different types of compacting equipment and by varying the amount of water
added manually to the refuse during compaction.
Preceding page blank
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It was found that compaction ranged between 1,189 and 1,383 pounds to the
cubic yard, that better results were obtained with a compactor than with a
bulldozer, and that the application of larger amounts of water to the refuse
improved effectiveness.
The feasibility of baling refuse and the degree of compaction obtainable by
this method were investigated at two levels: (l) ah extended local test was
conducted in which unprocessed refuse was baled in a leased light-duty baler
installed at a test facility especially constructed for this purpose, and (2)
arrangements were made for a demonstration of refuse baling by an interested ;
baler manufacturer, using modern, heavy-duty equipment.
In the local baling test a total of U8.5 tons of typical city-collected refuse
was processed during a five-week period into 162 bales averaging 599 pounds
apiece in weight and 689 pounds to the cubic yard in density. These bales
were classified as to composition of the refuse and were rated as to such
characteristics as shape, handling ease, odor absence, fines retention, and
liquid retention. As a second phase of this program, 6k additional bales were
produced and "nested" in a simulated landfill situation.
On January 9, 1968, at its plant in Bellevue, Ohio, the American Baler Company
conducted a demonstration of baling pre-shredded municipal refuse. The four
complete bales that were produced ranged from 1,500 to 2,^90 pounds in weight,
from 0.92 to 1.56 cubic yards in volume, and from 1,U66 to 1,593 pounds to
the cubic yard in density. On the basis of this experience and its background
of previous knowledge in the field, ttie company believes that densities
close to 1,900 pounds to the cubic yard are practicable. Bale densities of
this magnitude probably approach the maximum obtainable without resorting to
relatively slow, cumbersome, and expensive multiple stage baling presses.
Findings in both the local test and the factory demonstration tended to
supplement and reinforce each other. The balers used in both tests were of
the same basic horizontal design which lends itself to more continuous, higher
production than other types, Locally it was shown that ordinary city-
collected refuse can be successfully processed, even without pre-shredding,
into reasonably well-formed bales which generally maintain their integrity
during transportation and disposal. Since the local test involved a larger
quantity of materials (an estimated 65 tons in all as compared with perhaps
five or six tons at Bellevue) and extended over a period of time, it estab-
lished the feasibility of baling refuse which varies considerably in composi-
tion and moisture content from day to day and from one collection area to
another. The Bellevue test provided persuasive evidence of the desirability
of shredding the refuse before it is fed into the baler and of using baling
equipment of high compression capability. The factory-produced bales were not
only denser but better shaped, with sharp, well-defined corners and relatively
r.mooth surfaces, and they maintained their integrity without appreciable
distortion during handling.
Densities obtained locally are not competitive with the approximately 1,380
pounds to the cubic yard obtainable by efficient landfill methods, but the
compaction obtained at the factory exceeds that level. Based on the compac-
tion actually reached in that test (1,593 pounds to the cubic yard) and
8
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allowing five per cent of volume for voids between bales in place in a land-
fill, the space required per ton for refuse in bales would be 91 Per cent of
that required with our best present landfill methods. If the greater density
(1,890 pounds to the cubic yard) predicted by the company were reached and the
same allowance for voids made, the space required per ton would be 77 per cent
of that required with conventional methods. It follows that the potential
saving in landfill life that is realizable by baling can be expected to fall
between 9 and 23 per cent.
It is felt that the potential economic benefits of baling refuse can be fully
realized, however, only in the operational setting of a transfer station. The
project staff made preliminary studies of the economic feasibility of a full-
scale baling transfer station where the exhaustion of an existing favorably
located landfill would require longer direct haul to a more remote landfill by
collection vehicles. It was concluded that, under the San Diego conditions
studied, when the additional round-;trip distance required per truck by longer
direct haul exceeds about 10.1 miles the baling transfer station would be more
economical than direct hauling. It also appears that, in the station capacity
ranges studied (300 to 350 tons a day), a net savings can be realized by bal-
ing despite the baling operating costs because of the reduction in the cost of
land for the station site, in rehaul equipment, and in compaction.equipment
and labor at the landfill. This would make a baling transfer station (fully
equipped with balers, a hogger, and conveyors) more economical than a conven-
tional station in which refuse is simply transferred from collection to rehaul
vehicles. However, it should be noted that this conclusion might not be valid
if the comparison were made with a conventional transfer station of larger
capacity and consequently greater efficiency.
A pilot baling transfer station is needed (l) to test these tentative conclu-
sions under actual production conditions, (2) to refine baling techniques and
routines, (3) to ascertain the optimum moisture content of the refuse being
baled, (U) to compare the compaction obtainable with pre-shredded versus
unprocessed refuse, (5) to determine and deal with any possible nuisance
factors or health hazards (such as noise, dust, odor, and vector breeding) that
may be encountered in the operation, (6) to develop effective practices in
placing the bales in a landfill, (7) to explore the feasibility of other means
of bale disposal, such as in the reclamation of small canyons near residential
areas, and (8) to develop accurate cost comparisons. As a means of implement-
ing and proving out the combined baling and transfer concepts, a pilot baling
transfer station would in the long view be a potentially rewarding investment.
Recapitulation of Conclusions
1. The problem of disposing of solid waste materials, already formidable, is
growing in magnitude and complexity as urban populations continue to
increase and the per capital production of refuse continues to rise.
2. In many communities using sanitary landfills for refuse disposal this
problem is compounded by the imminent exhaustion of favorably located
landfill facilities and the prospect of longer direct hauls by collection
vehicles.
-------
3. The urgency of the situation has prompted investigation of a number of new
approaches that might offer alternative solutions to the problem. Among
these is the concept of baling refuse.
k. The process of baling refuse is physically and technically feasible with
presently available equipment and economically feasible when combined with
the transfer station concept.
5. Greater compaction can be achieved by baling than by use of standard com-
paction methods (bulldozer or compactor) in sanitary landfills.
6. Under certain frequently met conditions, baling transfer stations are more
economical than longer direct hauls by collection vehicles.
7« In the station capacity ranges studied, baling transfer stations are more
economical than conventional transfer stations.
8. A pilot baling station is needed to test the findings and tentative con-
clusions of this study and investigation project.
10
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CHAPTER III
PHYSICAL FEASIBILITY OF BALING REFUSE
A review and appraisal has been made of the background, present status, and
expected growth of the tasks of solid waste collection and disposal in San Diego.
It is evident that both the magnitude and the cost of the city's already for-
midable task in performing these functions will increase in the future. San
Diego is not unique in this respect. There are few if any municipalities using
landfills for solid waste disposal that do not face to some degree the prospect
of mounting quantities of refuse, dwindling space in favorably located disposal
sites, and greater expenditures for sanitation operations.
, This situation here and elsewhere has led to the exploration and consideration
of a number of new techniques and procedures that may give promise of allevi-
ating the solid waste disposal problem. Among these is the possibility inves-
tigated in this project and described in this report - the baling of refuse.
'The physical feasibility of applying this process in the solid waste field is
discussed in this chapter. Its economic feasibility, particularly as related
to the transfer station concept, is examined in Chapter IV.
The Baling Process
Baling may be defined as the process of applying pressure to loose, compress-
ible materials within an enclosure and binding the compacted mass while it is
in a confined condition. The.resultant object is a bale.
Widely used for many years in industry and agriculture, the baling process is
perhaps the simplest and most economical form of packaging. In essence no
encasing or wrapping are required to maintain the integrity of the bale and
the cohesion of its contents. The compaction inherent in the process contri-
butes to the conservation of space and consequently to economies in storage
and transportation. In the weights in which they are usually produced on the
farm arid in the factory, bales are readily handled by manual or mechanical
means. Typically their surfaces are rectangular in shape and relatively
smooth and they can be stacked and nested economically without excessive voids
and waste space. For these reasons baling is often used in the packaging of
certain types of raw materials, scrap, staple commodities, and manufactured
products. The United States Department of Commerce has listed 53 different
commodities that have been successfully baled for transit. These range from
excelsior to textiles and from feathers to tobacco.
Quoted in Stern, W. The package engineering handbook. Rev. version.
Chicago, Board Products Publishing Company, [1949]. p. 38.
11
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In most applications in agriculture and industry, baling is used for the com-
pressing and packaging of relatively homogeneous materials - cotton, hay,
paper stock, and rags, for example. With such commodities the process is
relatively standardized and more or less trouble free because the materials
are relatively uniform in composition and in the size and shape of their
constituent elements. They present few surprises. Foreign objects that might
damage the mechanism or require frequent adjustments in the process are seldom
encountered. Potential compressibility is known within reasonable limits.
A major complication in adapting the baling process to municipal refuse is
that this material lacks such homogeneity and predictability. It.is true that
the composition and character of mixed solid wastes have been analyzed and
described in a general way. On the average, its characteristics may be dis-
tinctive in different parts of the country, from city to city, and even from area
to area within the same community. Nevertheless, any given batch fed into a
baler hopper may differ markedly from that average, may present unusual prob-
lems, and in the completed bale may vary widely from the norm in density.
These problems strongly indicate a requirement to investigate and evaluate
the need for certain techniques and procedures preliminary to the actual bal-
ing process: (1) some means of controlling the composition of the input, such
as by limiting it to city-collected refuse and by imposing certain restrictions
on the kinds of materials that will be picked up, (2) sorting out non-balable
items, arid (3) pre-shredding the materials to reduce their heterogeneity.
Balers are manufactured in a number of different types and sizes to meet the
special requirements imposed by the quantity and character of the materials to
be baled. They may be stationary or portable. They range in size from small,
manually operated balers that are suitable for small offices or .plants to
powerful briquetter presses that can reduce an automobile to a small cube of
compacted metal.
Heavy, production type balers are hydraulically or electrically operated. They
are generally classified into two major types depending on the direction of
movement of the compressing ram: (1) vertical stroke balers, which are sub-
classified as down-stroke or up-stroke (so called "pit" type) balers and (2)
horizontal stroke balers. In vertical stroke balers the materials are com-
pressed between a moving ram (a piston with a flat faceplate or "platen" the
size of one face of the bale) and the fixed floor or ceiling of the compres-
sion chamber. Vertical stroke balers have the disadvantage that time and
effort are required to remove the completed bale before the chamber can be re-
charged and the production of a new bale begun. This type has the advantage,
at least theoretically, of greater compaction for the same expenditure of
energy. Compound or multiple stage balers, in which pressure is applied
vertically and then horizontally or vice versa, produce still greater compac-
tion but are even slower in operation. In the horizontal stroke baler the
ram moves laterally against the end of the bale being formed and in the
process not only compresses the materials but also pushes the bales (the one
being formed and one or more already completed) toward ej ection through an
elongated chamber and out its open end. The completed bales still lodged in
the chamber before ejection act as a plug and 'provide resistance to the ram
-------
In the production of a new bale. A tension adjustment at the perimeter of the
open end of the chamber allows this resistance to be increased or decreased as
needed.' The process is continuous in that a completed bale need not be
removed before starting a new one. A minor disadvantage of this type of baler
is that it is harder to feed than a pit baler because the material must be
elevated. The theoretical loss of compacting power inherent in this design is
probably more than offset by the fact that the bale is automatically ejected.
As a matter of fact the horizontal stroke baler appears to be the only type
presently available that has a production rate high enough to handle the large
quantities of material that are normally involved in a refuse operation.
In most applications, bales are customarily bound with wire or with flat metal
straps. In the present state of the art, these must be tied or secured manu-
ally which is time-consuming and expensive for a high production operation.
The chief obstacle in the way of automatic tying appears to be the expansi-
bility of the material and the spring-back of the compacted bale when the
pressure of the ram is relieved. Another difficulty arises from the clogging
(with compacted material) of slots in the face of the platen, through which
the wires or straps must be threaded. The solution of these problems - and
they do not seem to be mechanically insurmountable - will be a major break-
through. There are indications that one or more baler manufacturers are
developing devices for this purpose and that there is a reasonable prospect of
success in the near future.
The Baling of Refuse
As part of the evaluation of the feasibility of refuse baling as a means of
conserving sanitary landfill space, a major objective of this project, it is
necessary to appraise and compare the effectiveness of two methods of compac-
tion: (1) by conventional landfill techniques and (2) by baling. The first
of these was investigated by making field surveys to determine the weight and
compacted volume of refuse now being deposited, and the second by actually
baling refuse in controlled test situations. Other objectives of the tests
were to investigate the mechanical feasibility of baling refuse and to deter-
mine what problems might be encountered with the disposal of completed bales
in a simulated landfill situation.
The feasibility of baling solid waste materials and the degree of compaction
obtainable by this method were investigated at two levels: (1) ah. extensive
local test was conducted using a leased light-duty baler installed at a test
facility especially constructed for this purpose, and (2) arrangements were
made for a demonstration of refuse baling by an interested baler manufacturer,
using modern, heavy-duty equipment.
Local Refuse Baling Tests
Early in the project, local San Diego business firms having balers were sur-
veyed so that arrangements could be made to conduct actual testing of the
feasibility of baling refuse. Originally it was contemplated that this test-
ing would be done on the baler owner's premises on week-ends or at other odd
times when he was not using the equipment. When it was found that a baler
could be leased outright for a period of time, however, it was decided to
13
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install it on city property and thus create a test situation that would be
better controlled, more comprehensive, and more realistic than would have been
possible under the original plan. Accordingly, a test facility was designed
and constructed on city property near the Chollas sanitary landfill. The
criteria for the selection of a baling test site were accessibility, proximity
to a disposal site, suitable topography, and availability of power and water.
As constructed the test facility had, at an upper level, a paved dump area
adjacent to a wooden ramp and chute designed for feeding refuse into the leased
"Balemaster" horizontal stroke baler mounted on a concrete pad at a lower level.
It was equipped with a hoist for handling completed bales, was.provided with an
access road and a paved area for the maneuvering of mobile service equipment
(refuse packer truck, dump truck,, and a leased skip loader), and was completely
enclosed by a chain link fence. Power and water were brought in from nearby
sources. Views showing the design and operation of the test facility appear in
Plates 1 to 4 on pages 15 to 18.
The local baler test program began on December 11, 1967, and ended on January
19, 1968. It was conducted on an experimental rather than a production basis.
On a typical day, three to four tons of refuse were handled and from twelve to
fourteen bales were produced. They were measured and weighed, their densities
were computed, they were classified as to composition, and a number of bale
characteristics such as shape, ease of handling, and absence of odors were
evaluated.
The nucleus of the four-man crew consisted of an equipment operator and a
laborer from the Public Works Department. One full-time member of the project
staff was assigned regularly to the test program crew and the other two full-
titae members served alternately in this capacity, so that all three became
thoroughly conversant with the process through active participation in the
work.
During the test period this crew processed 48.5 tons city-collected refuse into
162 bales averaging 599 pounds apiece in weight and 689 pounds to the cubic
yard in density. The bales ranged in weight from 335 to 900 pounds, in volume
from 0.3 to 1.4 cubic yards, and in density from 370 to 905 pounds to the cubic
yard. A day-by-day summary of weights and densities recorded is shown in Table
1 on page 19 and the distributions of weights, volumes, and densities of all
the bales produced during the test period are shown graphically in Plate 5 on
page 20.
The composition of the refuse baled was classified by visual inspection and
found to be about 21 per cent "typical San Diego refuse," about 17 per cent
"excessive garbage," about 60 per cent "excessive paper," and about two per cent
"excessive prunings." None of the bales were judged to fall in the other two
composition categories that had been set up for the test - "excessive fines" and
"excessive water."
It was found that there were substantial differences in the average densities
of bales in each of the three leading categories described above (omitting
"excessive prunings" as having too few cases to support a valid comparison).
The average density of those bales judged to be composed of "typical San Diego
14
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DESIGN AND OPERATION OF THE LOCAL TEST FACILITY FIGURE 1
'
General view of
test facility
during construction
Refuse is dumped
at the upper level
A skip loader cuts
into the pile of
refuse
This page is reproduced at the
back of the report by a different
reproduction method to provide
better detail.
15
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DESIGN AND OPERATION OF THE LOCAL TEST FACILITY
FIGURE 2
End view of upper
ramp leading to
baler hopper
Refuse "bridging"
at throat of chute
has tc be manually
dislodged
Water is applied
to refuse as it
enters chute
NOT REPRODUCIBLE
-------
DESIGN AND OPERATION OF THE LOCAL TEST FACILITY .FIGURE 3
Baling wires
are tied manually
Refuse descending
chute into baler
chamber
rom "xfyensi.'yr"
of baler cnamber
NOT REPRODUCIBLE
17
-------
DESIGN AND OPERATION OF THE LOCAL TEST FACILITY
FIGURE 4
Bales are pushed
along roller conveyor
Hoisting bale
from conveyor
Bales are placed in
dump truck for
transportation to
the fill
NOT REPRODUCIBLE
18
-------
TABLE 1
. SUMMARY OF LOCAL BALING TEST RESULTS .
(WEIGHTS AND DENSITIES ROUNDED TO NEAREST FIVE POUNDS)
Weight of Bales
Weeks
1
Days
Dec.
11
12
13
14
15
Sub -total
2
Dec.
20
21
Sub -total
3
Dec.
26
27
29
Tons of
Refuse
.800
1.775
4.200
3-700
1.225
11.700
2.025
1.125
3.150
4.925
2.150
5.100
No. of
Bales
3
6
13
13
7
42
7
3
10
13
7
20
Max.
575
600
750
800
350
800
615
750
750
780
665
600
(Lbs)
Mln.
450
550
575
335
350
335
550
750
550
735
575
450
Density of Bales
(Lb/Cu.Yd)
Ave.
535
575
645
570
350
555
580
750
630
760
615 .
520
Max.
600
835
675
830
405
835
700
780
780
850
630
600
Min.
475
680
590
575
370
370
620
780
620
700
575
495
Ave,
555
760
630
730
390
635
665
780
700
775
600
450
Sub-total
12.175
40
780 450 610
850 495 615
4 Jan
Sub-total
5 Jan
Sub -total
TOTALS AND
AVERAGES
• 3
4
5
. 8
9
10
5-075
4.075
2.500
11.700
3.650
2.250
3.900
9.800
48.525
16
13
8
37
13
8
12
33
162
750
900
650
900
650
590
690
690
900
600
575
625
575
500
540
625
500
335
635
630
640
630
560
565
650
595
600
895
900
780
900
740
670
905
905
905
560
620
770
560
625
670
795
.625
370
735
785
775
760
670
670
860
735
690
Note: Bale volumes were determined by individually measuring each bale. Bales
were weighed in groups of four and averaged. This average was used in
determining density.
19
-------
70
60
40
30
FIGURE 5
'
;.Lj
! I
-J—
•fi-
ll Dl
J til 18
tqlBi
S
10
j ; ;_
Hi}
1
too-
too
5dO
' *>°
CCQ
40
20
10
0
SO
^
cth
*!l
UL
t
..-i
06
of/ o|e
j •
10 i :
1- r L±_
F
"tti
*f
40
i:
30
20
4*
«.i$
:4:
10
-Ji4.iit
i i i
:I4|
tin :::: :;[: I tri.1Jr4-M-thi
300 400 500 600 700 800 900 1000
POUNDS per CUBIC YARD ,p(, 20 jmb 3-68
-------
refuse" was highest at 7^7 pounds to the cubic yard, of those with "excessive
garbage" next at 700 pounds to the cubic yard, and of those with "excessive
paper" lowest at 656 pounds to the cubic yard. By statistical (standard error)
analysis, the probabilities that differences between these averages are sig-
nificant were found to be 90 per cent as between "San Diego refuse" and exces-
sive garbage," 99 per cent as between "San Diego refuse" and "excessive paper,"
and 95 per cent as between "excessive garbage" and "excessive paper." It is
virtually certain, therefore, assuming that the judgments as to appropriate
classification were accurate, that the superior eompactibility of "San Diego
refuse" .as compared with "excessive paper" is significant and not due to
chance. The odds are nine to one that it is also superior to "excessive gar-
bage" in eompactibility.
It was noted above that "typical San Diego refuse" constituted only about -one-
fifth of all of the solid wastes processed during the test- The reason that
the composition of solid waste materials processed in the test was not repre-
sentative is probably that it was conducted during the Christmas season When
the incidence of paper in the refuse is higher than at other tiroes of the year.
These considerations suggest that if the baling test program had been conducted
throughout the year, or at a more representative season, average densities
would have been closer to the 7^7 pounds per cubic yard found for "San Diego
refuse" than to the 689 pounds per cubic yard actually obtained in the test.
Certain characteristics of the bales were evaluated by a member of the proj-
ect staff, using a scale from 10 (excellent) to 0 (totally unsatisfactory).
These appraisals are summarized in Table 2 on page 22. "Shape of bales" and
"fines retention" were judged to be fair to good, and "handling ease," "liquid
retention," and "odor absence" were rated good to excellent.
In the later stages of the test considerable pre-sorting of non-baleable mate-
rials was necessary. A large number of Christmas trees, received during the
two weeks following the holidays, and also a number of other bulky or exces-
sively long items had to be separated out manually because they could not be
fed into the baler. On some days these rejected materials constituted as much
as ten per cent of the volume of the refuse processed. This difficulty would
be minimized by hogging or shredding the refuse ahead of the baling operation.
Attempts to determine the effect on compaction of adding water to the refuse
during the baling process were inconclusive. It was found to be virtually
impossible to apply water with any degree of uniformity to raw, unshredded
refuse. Densities obtained during the first seven days of the test, when no
water was added, were almost identical to those obtained during the next nine
days, when water was added. A more significant factor appeared to be the
water content of the refuse as it arrived from the collection route. If it
was relatively wet, as after rainfall, compaction was increased and the shape
of the bales was improved. The effect of adding water to the refuse during
baling might well be the subject of future study under better controlled con-
ditions .
Two other serious problems were encountered: (l) tying the bale wires manu-
ally was rather time-consuming and constituted a real bottle-neck in the opera-
tion (this can probably be cured by the development of a workable automatic
21
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Table 2
SUMMARY OF RATINGS OF BALE CHARACTERISTICS
LOCAL BALER TEST
Judg-
ment
Scale
10
9
8
7
6
5
4
3
2
1
0
Total
S
Median
Q
Shape of
Bale
No.
0
18
44
46
24
10
13
4
1
0
2
162
8.5
7-6
6.4
JL_
0.0
11.1
27.2
28.4
14.8
6.2
8.0
2.5
.6
0.0
1.2
100.0
Handling
Ease
No.
3*
40
32
19
13
11
3
1
6
0
_3
162
9.8
8.8
7-2
_!_
21.0
24.6
19.8
11.7
8.0
•6.8
1.9
.6
3-7
0.0
1.9
100.0
Liquid
Retention
No.
58
28
24
8
2
0
0
0
0
0
0
120a
10.0
9-9
8.9
_i_
48.3
23.3
20.0
6.7
1.7
0.0
0.0
0.0
0.0
0.0
0.0
100.0
Fines
Retention
No.
10
31
44
33
13
16
9
2
1
0
_3
162
9.0
8.1
6.7
_1_
6.2
19.1
27.2
20.4
8.0
9.9
5-6
1.2
.6
0.0
1.8
100.0
Odor
Absence
No.
36
27
38
36
16
5
1
0
0
0
0
159*
9-9
8.6
7-5
_L_
22.7
17.0
23-9
22.7
10.0
3-1
.6
0.0
0.0
o.o
0.0
100.0
Note a - 42 bales were not judged on this characteristic,
b - 3 bales were not judged on this characteristic,
22
-------
tying device) and (2) jams due to "bridging" of the refuse as it was conveyed
toward and fed into the baler frequently caused stoppages and had to be broken
UP "by positive manual disloging of the material (this problem would be mini-
mized by pre-shredding).
After the conclusion of the initial phase of the baler testing program
described above, 6k additional bales were produced and "nested" in a hillside
shelf dug out for tLis purpose. A fork lift was used to stack the bales to a
height of three tiers. Approximately 55 cubic yards of baled refuse were dis-
posed of in this manner and covered with earth. Voids between the bales were
estimated at 15 per cent of their aggregate volume, so that a total of approxi-
mately 63 cubic yards of space were required to accommodate the 55 cubic yards
of refuse. These voids resulted from the impossibility of nesting the bales
as close together as desired, partly because of their somewhat uneven surfaces
and partly because a fork lift is not an appropriate device for this purpose.
To some extent the operator's view of his work is obstructed by the bale it-
self. Placing the bales vertically from above would be more effective than
moving them laterally from the tines of a fork lift. Future experiments may
show that a better machine for this purpose would be a crane of the clamshell
type but with flat jaws. Bales of higher compaction and consequently of better
shape, such as those produced with pre-shredded refuse at the American Baler
Company's demonstration (see the next section of this chapter), could undoubt-
edly be stacked more successfully.
Pictures of the disposal experiment described above are shown in Plates 6 to
9 on pages 24 to 27.
Manufacturer's Refuse Baling Demonstration
Early in the course of the project, the staff sent a total of fifty letters of
inquiry to all known baler manufacturers in this country as listed in MacRae's
Blue Book. Copies of this inquiry and the mailing list to which it was sent
appear in Appendix 2 of this report. The letter described the purpose and
scope of the project, requested brochures and information about the manufac-
turer's baling equipment, and invited comment and suggestions on the potential
adaptability of such equipment to the baling of municipal refuse. Twenty-five
responses were received. Four companies were out of business or their forward-
ing addresses were reported unknown. Of the number responding, ten do not
manufacture any equipment suitable for baling municipal refuse at all and
eleven manufacture only conventional balers designed for small applications
where continuous, high-capacity production is not required,. The remaining four
appeared to be promising in that they stated they planned to start or in some
cases had already started to engineer and construct balers specifically
designed for use with municipal refuse.
Follow-up letters were sent to these four firms affirming our interest and
suggesting meetings to discuss the equipment they now have or plan to develop.
In some cases these invitations were reaffirmed by long distance telephone
calls. Only one baler firm, the American Baler Company of Bellevue, Ohio,
responded to the extent of sending representatives to discuss detailed possi-
bilities and problems.
23
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VIEWS OF LOCAL BALE DISPOSAL EXPERIMENT FIGURE 6
Hillside before
"being cut to
create simulated
landfill
.
•
.
•
j
.
-*-
. •
-
-
Fill cutting jo'b
approaches completion
Some of the bales
are dumped on the
ground for pick-up
by the fork lift
This page is reproduced at the
back of the report by a different
reproduction method to provide
better detail.
24
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VIEWS OF LOCAL BALE DISPOSAL EXPERIMENT
Other bales are
transferred directly
from the truck to
the fork lift
Fork lift stacks
the bales in the
simulated fill
Stacked bales
are covered
with earth
NOT REPRODUCIBLE
25
-------
t
f
o
3 g
•P
VIEW OF LOCAL BALE DISPOSAL EXPERIMENT
Stacked bales
ewed from abovt
• .
-------
•so
m
T3
90
o
o
c:
O
CO
; j
•-j
' t '-t'i '
'
VIEWS OF LOCAL BALE DISPOSAL EXPERIMENT
^SSrrtl&SL f.f :•»'' . *«*'
£z£^&-: -:.V-' i >^^tV- v
•f§T'~- .-•'". ^ -Si*" x A / '
j^>;"';.'^'"" <^'--
ftfiS^'..^! V ••i-^.,'^ \:j&t f-r1'*7-
•' /; .i*:'-»*
Si'.*. S*
Front view of "bales
"nested" in the fill
N
• M
O
. M
-------
-
m
j.* ««*
- . AVt^^^^HHB^^S^^n*^
FACTORY RT,?lr::- BAILING Df24CKSTRATICN
.
Shredded, materials are descending
through baler hopper and bales are
being compressed and extruded at
left. Note black spacer between bales,
-------
FACTORY REFUSE BALING DEMONSTRATION
I
t
A
i
•
;. <••'', *
'
!
Completed bale is emerging
from chamber
-------
As a result of these conversations, this firm offered to conduct, at its own .
plant and at its own expense, preliminary tests of the feasibility of baling
refuse. This demonstration took place on January 9> 1968. It was witnessed
by San Diego's Project Coordinator, by the Reviewing Officer of the United
States Public Health Service's Office of Solid Wastes, co-sponsor of the proj-,
ect described in this report, and by other interested observers. Appendix 3
is a verbatim copy of the company's notes on this demonstration.
The material baled in the Bellevue test was pre-shredded rather than raw
refuse. On the basis of its long experience with designing balers for a
variety of materials the company is convinced that the baling of refuse can not
be accomplished effectively without pre-shredding. They believe that unless
this is done bale densities will be lower, it will be Impossible to add neces-
sary moisture to the materials with any degree of uniformity, an excessive
amount of fines will be lost, more pre-sorting will be necessary^ an
-------
perhaps five or six tons at Bellevue) and extended over a period of time, it
established the consistent and sustained feasibility of baling refuse which
may vary considerably in composition and moisture content from day to day and
from one collection area to another.
The average compaction obtained in the local test, 689 pounds per cubic yard,
was only about half as much as would be required to match the approximately
1,380 pounds per cubic yard obtainable by conventional landfill methods. How-
ever, densities exceeding that level were attained at Bellevue with modern,
heavy-duty equipment. Based on the compaction actually obtained in the factory
test and allowing five per cent of volume for voids between bales in place in
a landfill, the volume required per ton for baled refuse is 91 per cent of that
required with conventional landfill methods. If the greater density guaranteed
by the company were reached (and the same allowance for voids made), the volume
' needed per ton would be 77 per cent of that required with conventional methods.
It follows that the potential saving in fill life that is realizable by baling
can be expected to fall between 9 and 23 per cent.
The marked difference in bale densities obtained in the two tests - more than
twice as great at the factory as in the local test - was primarily due to (1)
the amount of pressure applied (approximately 140 as against approximately 20
pounds to the square inch respectively), (2) the moisture content of the refuse,
and (3) the pre-shredding of the material. Pictorial evidence of the impor-
tance of pre-shredding is shown in Plates 12 through 15 on pages 32 through 35.
One of the important functions that could be served by a pilot baling transfer
station such as that described in Chapter IV of this report would be a deter-
mination, under controlled conditions, of the relative contributions of each
of these three factors to the high densities attained at Bellevue^ A limited
amount of experimental evidence has already been built up on the effect of the
first two factors (pressure and moisture) on the compaction of refuse. Den-
sities obtained by increased compressive loads up to 100 pounds to the square
inch were studied at Chandler, Arizona, as early as 1954.2 Los Angeles County
has conducted similar tests and arrived at comparable findings. Neither of
these investigations involved baling directly, and both of them dealt with
refuse that had not been pre-shredded. The American Baler Company has assem-
bled data on the relationship of pressure to density based on the baling demon-
stration described above and also on some earlier tests made in 1963, applying
pressures up to 760 pounds to the square inch to pre-shredded refuse, and has
derived the parameter curves shown in Plate 16 on page 36..! The curves in all
of these studies show a characteristic pattern of continued but diminishing
increments of density as pressure is increased. A point is eventually reached
at which further application of energy is no longer economically feasible be-
'cause of the minimal improvement of density and because the strain such
pressures impose upon the machine leads to excessive maintenance costs. Where
this point falls is still a matter of practical judgment rather than of
scientific determination because up to now experience in the baling of refuse
has been extremely limited. Evidence of the efficacy of increased moisture
2Quoted and shown graphically in American Public Works Association.
Municipal refuse disposal. 2d ed. Chicago, Public Administration
Service, 1966. p. 53-54.
31
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IPS
' -JiIALS^ LOCAL -'
-------
50
O
o
CO
U3
CCWPARISON OF RAW MATERIALS, LOCAL AND FACTORY TESTS
Refuse in shredded form was
used in the factory tests
M
! G
-------
COMPARISON OF
FINISHED PRODUCT
These bales were produced
in San Diego's local test
H
O
-------
t)
50
O
O
CD
-
i-
§
pa
r
H
1 •
-------
FIGURE 16
0 TONS ' 10 'PER 201 SQ. '30 FT
-------
content in improving the density of compressed refuse was found in the compac-
tion tests in a landfill situation (but presumably also applicable to baling).
It was noted earlier in this chapter that the American Baler Company's guarantee
of high density with their equipment is conditioned in part on a 30 per cent
content of moisture in the material. Further study of the optimum percentage of
moisture is needed.
The pre-shredding of refuse is also a condition of the company's guarantee.
It is felt that this requirement is not arbitrary or capricious. It is based
on the company's own experience and the opinions of three private firms now
investigating the baling of refuse who are convinced that pre-shredding is
essential for the reasons stated in the preceding section of this chapter. One
of these firms, the Southern Railway Company, is reported to have estimated
that shredding costs will be approximately 50 cents a ton. This figure is con-
sistent with the findings of preliminary cost studies made by the project staff
in connection with its investigation of the economic feasibility of baling
transfer stations. This aspect of the project is discussed in. Chapter IV of
this report.
Summary of the Chapter
Although the baling process has long been used for packaging a wide variety of
agricultural and industrial commodities, the concept of applying it to the
solid waste field is relatively new and presents some technical difficulties.
The physical feasibility of this application and the degree of compaction
obtainable by this method were investigated by actually baling refuse in an
extensive local test (162 bales) and in a baler factory demonstration. The
findings of the two tests tended to corroborate each other. In the local test
a large quantity and variety of raw, unprocessed refuse was successfully baled
over a period of time, but the average density obtained was slightly less than
700 pounds to the cubic yard. Although the factory demonstration was more
limited in scope, the'four bales that were produced averaged about 1,500 pounds
to the cubic yard in density and were superior in shape ard integrity.
Densities obtained locally are not competitive with the approximately 1,380
pounds to the cubic yard obtainable by our best landfill methods. The fact
that compaction obtained at the factory exceeds that level is attributable to
greater pressure, high moisture content, and the pre-shredding of the material
before it was baled. The tests indicate that baling refuse not only is
physically and technically feasible but also has great potential as a means
of conserving landfill space in San Diego and elsewhere.
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CHAPTER IV
ECONOMIC FEASIBILITY OF BALER TRANSFER STATIONS
It was established in Chapter HI of this report that it is physically and
technically feasible to bale city-collected refuse with presently available
baling equipment. It was shown further that when this equipment has high
compression capability and when the refuse materials are pre-shredded, it is
possible to obtain significantly greater compaction by this means than has
been obtained by our best present landfill methods.
It is believed that the potential economic benefits of baling refuse can be
fully realized, however, only in the operational setting of a transfer sta-
tion. It will be shown in this chapter of the report that a functional
integration of the baling and transfer concepts is the key J;o substantial
savings when the exhaustion of favorably located facilities requires longer
direct hauls by collection vehicles to a more remote landfill.
The essential requirements of the refuse baling process, as described in
Chapter IH> virtually dictate that it be performed at an intermediate point in
the collection-disposal sequence. To produce the degree of compaction neces-
sary to prove out economically the baling press must have high compression
capability and must therefore be heavy, massive, and stationary. Since the
most effective compaction can probably not be achieved without pre-shredding,
another heavy piece of equipment for this purpose is also needed. These
technical requirements make impracticable, at this time, some of the ideas
that have occasionally been advanced: (l) balers in residences and shops
(so-called point of origin processing analogous to the garbage-grinding dis-
posal units now in widespread use), (2) installation of baling devices in
refuse collection vehicles, and (3) separate portable balers that might be
transported from one collection area to another.
The other possible alternative - placing the baling operation at the landfill -
reduces flexibility (the plant may not be well located for subsequent use when
the fill is completed) and eliminates the possible savings that might be real-
ized by the strategic location of a baling transfer station near the center
of a collection area. It is axiomatic that to the extent that more time must
be spent in hauling refuse, as the distance increases between the area of
origin and the point of disposal, less time is available for actual collec-
tion. Therefore, additional vehicles and crews must be placed in service to
complete the route. Formulas developed by the project staff for determining
the number and cost of such replacement vehicles are described in a subse-
quent section of this chapter.
Conventional Transfer Stations
In an earlier period of sanitation service history, horse drawn wagons were
used to collect and haul refuse to the disposal site. In those times, this
method worked well for relatively short hauls. Four miles was the usual
38
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maximum distance beyond which it was more economical to use the transfer con-
cept.1 In early transfer operations, refuse was removed from the collection
wagons at central locations and placed in larger wagons for re-haul to the
landfill. The system had the advantages of decreasing the time, distance,
and cost of hauling by collection vehicles and increasing the time available
for collection.
The motorized vehicles that replaced horse drawn wagons had sufficient speed
to overcome the problems of additional haul time. The economics of direct
haul became more favorable and the advantages of transfer diminished or dis-
appeared. As urban areas continued to expand, however, problems of additional
haul time began to reappear with increasing frequency as the distances between
collection areas and disposal sites increased. This new cycle is resulting in
a revival of and economic justification for the old transfer idea, but in
terms of modern equipment and practices.
Although there is considerable variation in the designs of individual trans-
fer stations now in use, the basic concept of removing refuse from collection
vehicles to supplementary transportation vehicles remains unchanged. Most
conventional transfer stations can be categorized as either direct dump sta-
tions or storage-type stations.2 In direct-dump stations, collection vehi-
cles at an upper level empty refuse into re-haul vehicles positioned at a
lower level. In the transfer stations of this type operated by the Sanitation
Districts, Los Angeles County and "by Orange County, California, a loader
equipped with a "clamshell" type bucket distributes solid waste materials in
the re-haul vehicle and effects some compaction by tamping the refuse.3 New
York City operates a water-side station where collection vehicles dump their
loads into barges which are then towed to the disposal site.4 Storage-type
stations involve various methods of rehandling the material. Cranes or der-
ricks are sometimes used for transferring an accumulation of dumped refuse to
the re-haul vehicles. Another arrangement utilizes a conveyor belt and hopper
system. "The material is dumped from the collection trucks into pits so
shaped that the refuse falls by gravity to the conveyor. The hopper is con-
structed high enough to permit the transfer vehicles to drive underneath to
be loaded."' In other variations of this type, workers pick salvageable
materials off a slowly moving conveyor belt or electromagnetic devices remove
the ferrous metals.
1American Public Works Association. Refuse collection practice. 3d ed.
Chicago, Public Administration Service, 1966. p. 203.
2Ibid., pp. 213-215.
3Pictures of the transfer station operated by the Sanitation Districts
of Los Angeles County appear in Plate 17 on page 40.
4Ibid., pp. 21U-215.
5Ibid., p. 214.
39
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VIEWS OF A CONVENTIONAL TRANSFER STATION FIGURE 17
Refuse vehicles
weigh in at the
scale house
They proceed to the
upper level of the
station
Loads are dumped
into re-haul vehicles
stationed below
NOT REPRODUCIBLE
This loader is used
to spread and tamp
refuse in the trailer
(Courtesy of Sanitation Districts,
Los Angeles County, California )
40
-------
The simplicity of the design of these transfer stations makes for easy,
expeditious operation with relatively few stoppages due to equipment failure.
They have the disadvantage that in the transfer process much of the compac-
tion obtained in modern collection vehicles is lost due to fluffing and
spring-back of the materials when they are extruded from the packers. Greater
volume per unit of weight is thus required in the re-haul vehicles than would
be needed if the refuse had the same density as in the packer truck. For this
reason it is usually necessary to use both a semi-trailer and a full trailer
in order to haul efficiently with tonnages approaching legal load limits, thus
increasing costs and reducing maneuverability. This is a major inherent weak-
ness and it can be eliminated only by introducing into the transfer station
some more effective form of compaction process than simple temping. i
The net savings realizable by conventional transfer stations are limited to
those related to collection and haul costs. Operations at the disposal site
receive no direct economic benefit. The compacting methods that must be used
there are identical whether the refuse is received from re-haul vehicles or
from packer trucks. The incorporation of baling in the transf&r station oper-
ation, on the other hand, is a promising means of realizing additional net
savings not only by effecting significant reductions in disposal costs but by
reducing the number of trailers needed for re-haul. With baling, the legal
load can be carried in one trailer instead of two.
The Proposed Pilot Baling Transfer Station
A pilot baling transfer station is needed (l) to test the baling process
under actual production conditions, (2) to refine baling techniques and
routines, (3) to compare the compaction obtainable with pre-shredded versus
unprocessed refuse, (k) to ascertain the optimum moisture content of the
refuse being baled, (5) to determine and deal with any possible nuisance fac-
tors or health hazards (such as noise, dust, odor, and vector breeding) that
may be encountered in the operation, (6) to develop effective practices in
placing the bales in a landfill, (7) to explore the feasibility of other
means of bale disposal, such as in the reclamation of small canyons near
residential areas, and (8) to develop accurate cost comparison under actual
operating conditions.
Certain preliminary comments are necessary, however, before the pilot baling
transfer station which has been proposed to serve these purposes is described.
The fact that the proposed station is a prototype has a number of specific
implications:
A. Since some of the mechanical procedures involved have not been vali-
dated for the purposes contemplated, the station layout described in
this chapter was based on the design theory of staff engineers and
the opinions of consultants familiar with the individual items of
mechanical equipment.
41
-------
B. The designs and sketches presented herein describe a pilot "baling
transfer station rather than a full-scale plant. This j,s the prudent
approach to any new operational procedure, however promising, that
involves a substantial capital outlay. In previous experience, baling
municipal refuse (as discussed in Chapter III) has been experimental in
nature and limited in scope. It should be thoroughly tested and
evaluated on a reasonably large scale under actual operational condi-
tions. Because of its specialized purpose and smaller capacity, how-
ever, a pilot plant is somewhat at a disadvantage in economic compari-
sons with (l) present methods of landfill operations (because it would
disrupt present large-scale operations), (2) a conventional transfer
station, and (3) a full-scale baling transfer station.
C. The pilot station design should be realistic. It should include not
only «O1 of the basic essential elements but also, if possible, some
of the desirable features that will - if the pilot operation is
successful - be incorporated in a subsequent full-scale plant. The
purpose is to reduce labor cost, which in any such undertaking consti-
tutes the major portion of estimated annual expenditures, and to mini-
mize possible problems that might be associated with human error
during the operation.
In general, the refuse baling transfer station differs from the conventional
transfer station in three distinctive respects: (l) the presence of special-
ized processing equipment, (2) a more sophisticated system of conveying the
materials from one stage to the next, and (3) the state of the refuse at the
completion of the operation.
A plan drawing of the proposed pilot baling station, which would be capable of
processing 150 tons of refuse a day, appears in^ Plate is on page 43 and eleva-
tions are shown in Plates 19 and 20 on pages 44 and 45 . As designed, the
functional point of refuse entry into the actual plant operation is a dumping
pit large enough to accept up to four packer trucks at a time which will also
serve as temporary storage space for up to 100 cubic yards of refuse. Two
belt type conveyors in the bottom of the pit, each four feet wide, transport
the refuse into the plant. Since these belts are designed to "be operated
independently and at either simultaneous or differing speeds by remote con-
trol within the station, they can be manipulated to break up bridging of
refuse that might occur in the storage pit. For purposes of safety, hand-
operated trip mechanisms would also be installed at strategic locations.
At the inbound ends of the twin belt conveyors, refuse is fed into a rectan- .
gular hopper leading to the hogger (shredder) for the first phase of refuse
processing. Immediately above the hopper near the ends of the pit belt con-
veyors, a separate breakdown conveyor operates to expedite and meter the flow
of refuse into the hopper (see Plate 19 on page 44). It is expected that this
device will tend to feed refuse into the hogger at a uniform rate and prevent
surges in the operation.
42
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1 FIGURE 18
Roller conveyor
Belt conveyor
(baler feed)
Twin belt or roller conveyors for plant storage
(12 bales)
Loading dock
Verticol conveyor
Subterrean hogger room
Hogger
oth of packers .---
Dump this side only
62'
Dumping pit
-Twin belt conveyors alternate use.
pathof
•o
o
o
Emergency
dump
or ea
Scale l" = 20'
PILOT REFUSE BALING TRANSFER STATION
Design Capacity 150 tons/day
43
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Enclosed
belt conveyor
B
Baler hopper-,1
grd. line
xVerticol
bucket
conveyor
C conveyor belt
PIT
sump
I
I" = 10'
ELEVATIONS OF PILOT BALING STATION
Sheet I of 2
jmb 2-20-68
-------
RoMer conveyer or trai'le/
I—{—j 1 I with roller bed
Bojles; j J _J
—Same point
at 90°
roller
, convey or-g
B
Bucket conveyor
Belt conveyor
• Baler hopper
Ba ler
B
HKtttff
ELEVATIONS OF PILOT BALING STATION
Sheet 2 ot 2
I" = 10'
jmb 2-20-68
-------
The subterranean location of the concrete building housing the hogger and its
hopper has the advantage of tending to contain dust and "fly" refuse from the
hogger and to suppress the noise of the operation.
After being processed through the hogger the refuse materials, now in frag-
ments no larger than from four to six inches, fall onto a belt typeiconveyor,
are transported^ to an enclosed vertical bucket type conveyor, elevated therein
to a height of fifty feet, fall onto another short belt conveyor, and finally
drop into the baler hopper for the second phase of processing (see Plate 20
j on page 45).
The baling press, housed in an enclosed structure to permit operation during
inclement weather, produces uniform bales at an estimated potential rate of
one every three minutes. Experience in this field shows that this interval is
long enough for two men |to hand-tie the bales (if automatic tying devices
become available some of this labor cost could be saved). The bales emerge
from the press onto a roller conveyor and are then mechanically pushed 90
degrees onto twin roller conveyors. They move on these to the end of the
loading dock and directly onto the re-haul vehicle, the bed of which is it-
self equipped with rollers. This vehicle (a semi-trailer) is positioned on an
incline, so that the bales roll into place by the force of gravity. As soon
as one vehicle is fully loaded and departs for the disposal site, another is
parked at the dock and the loading process continues.
Cost of the Proposed Pilot Station !
It is estimated that the proposed pilot baling .transfer station described in
the preceding section of this chapter can be built on city owned land and
completely equipped, including the hogger, baler and all necessary appurte-
nances, for $201,000. An itemized breakdown of capital investment costs is
presented in Table 3 on page 47.
Estimated current operating costs for one year, totaling $127,200, are given
in Table 4 on page 48. The estimated cost of hauling completed bales to the
landfill is shown as part of plant expense, and the cost of equipment and
labor for the actual disposal of the bales at the fill is shown separately.
Because of the specialized, evaluative purpose of the pilot plant and its
presumably short life expectancy, computation of annual costs of amortization
would not be appropriate.
Conventional versus Baling Transfer Stations
Conventional Transfer Station
The chief advantages of a conventional transfer station are: (1) it is rela-
tively easy to plan and construct, (2) its basic operating procedures are
simple and direct, (3) it can accept a wide variety of refuse materials in- .
eluding certain problem items that normally can not be shredded or baled, (4)
transfer of the refuse is accomplished quickly, and (5) the absence of com-
plex machinery minimizes the possibility of a complete station shutdown due to
equipment failure.
46
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TABLE 3
ESTIMATED CAPITAL EXPENDITURES FOR PILOT BALING TRANSFER STATION
1.
2.
4.
Item
Site Preparation
Site Grading
Paving (8,000 sq. ft.)
Contingencies
Dumping Pit
Structural Excavation
Concrete Pit (34 cu. yd.)
Hardware
Pit Conveyors w/motors
Contingencies
Amount
$ 500
2,88C
320
Sub-total 5,800
30C
4,000
3,000
28,000
3,500
Sub-total $ 38,300
Hogger Pit Building
Concrete Building
Structural Excavation and Backfill
Breakdown Conveyors (2)
Hammer Mill
Coupler, Hopper, Motor and Starter
for Hammer Mill
Bucket Conveyor for 50' Lift
Sump Pump and Drain Line
Air Blower with Conduit
Ladder
Lighting
10$ Contingencies*
Sub-total
Baler Building
525 sq. ft. Building
Earthwork
Truck Dock 340 sq. ft.
Baler
10' Belt Conveyor
60' Roller Conveyor
Lighting
Electrical Service and Power Panel
Water Service (by City Forces)
10$ Contingencies*
Sub-total
$ 8, ooo
800
3,000
32,000
21,475
10,000
1,500
1,000
450
1,000
2,575
$ 81,800
$ 5,250
600
2,800
35,500
2,000
6,000
1,000
18,000
1,800
3,750
$ 7b,700
TOTAL CAPITAL INVESTMENT $201,100
Contingencies not computed on heavy machinery.
-------
TABLE 4
ESTIMATED CURRENT OPERATING\]XPENSES
OF PILOT BALING TRANSFER STATION FOR ONE YEAS
Item
Plant Operation Costs
1. Re-haul equipment $ 15,$60
2. Plant Labor
2 heavy truck drivers $ 17,7^0
1 utility foreman 10,26?
2 laborers 15,322 $ ^3,329
3. Maintenance and repair 6,^76
k. Electrical power and water costs 7,000
5. Bale ties and supplies 10,000
Bale Disposal Costs
1. Crane rental 10,200
2. Labor (equipment operator and laborer) 15,^50
3. Bulldozer for covering (l,000 hrs @ $lVhr) 14,000
U. Bulldozer operator (1,000 hrs) 5,185
TOTAL ANNUAL OPERATING COSTS $127,200
48
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As compared with a full-scale baling transfer station, the disadvantages asso-
ciated with the conventional station include: (1) higher station total opera-
ting costs (including re-haul costs), (2) larger land area required, (3) loss
of much of the compaction obtained in the collection packer truck, (4) larger
number of re-haul vehicles for comparable tonnages of refuse transferred, and
(5) higher cost of disposing of raw refuse at the landfill (see Table 9 on
page 6.4).
Baling Transfer Station
In the main, the disadvantages and advantages of the baling transfer station
are the converse of those set forth above. Disadvantages of the baling trans-
fer station include: (1) more difficult to plan and construct, (2) greater
complexity in operating procedures, (3) greater vulnerability to stoppages
due to equipment failure, (4) slower process at transfer station although
offset by less time required at fill site, (5) greater possibility of public
objection to the noise of the machinery, and (6) the character of the refuse
must be controlled due to technical limitations of the hogger.6
As compared with the conventional transfer station, the baling transfer sta-
tion offers the advantages of: (1) lower annual operating costs (including re-
haul costs), (2) smaller land area required, (3) fewer re-haul vehicles needed,
(4) lower cost of disposing of bales at the landfill, as compared to raw refuse,
(5) extension of fill life through greater compaction, and (6) utility of refuse
in baled form for constructive purposes such as small canyon reclamation.7
Transfer Station Location
Regardless of type, the transfer station "should: (1) be located as near as
possible to the center of production of the collection area which it serves,
(2) be convenient to the secondary or supplementary means of transportation,
(3) be so placed that there will be a minimum of public objection to the
transfer operations, and (4) be located at points where the construction and
operation will be most economical."8
These and other criteria for the choice of a location for a transfer station
are set forth in Table 5 on page 50 which was developed by the project staff.
These considerations are chiefly oriented to permanent, full-scale stations
6 For this reason, the proposed pilot baling transfer station would process
only city-collected refuse. Installing heavier-duty hoggers in subse-
quent full-scale stations might permit acceptance of privately transported
materials which, although they are more heterogeneous in character, con-
stitute 60 per cent of the city's refuse. In any case, convenient close-
in landfills would be available to such private transporters for a longer
period because of the extended fill life resulting from baling city-
collected refuse.
7 As pointed out in Chapter I, San Diego has many such canyons which can be
surveyed and evaluated for conversion by this means into useful and
attractive park and recreational areas. See Chapter V for a discussion
of small canyon reclamation.
8 Ibid., p. 210
4-9
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TABLE 5
FACTORS FOR CONSIDERATION IN LOCATION OF TRANSFER STATIONS
I. GENERAL LOCALE OF SITE(s)
A. Proximity to theoretical center of the collection areaa served.
B. Proximity to population movements as they affect collection areas.
1. Probability of present routes served being reduced.
2. Probability of new collection routes being added to the transfer
operation.
3. Location of future transfer stations.
C. Character of the area in relation to possible public objection to a
transfer station.
1. Residential development. ,
2. Commercial development.
3. Industrial development.
k. Miscellaneous (recreational, hospitals, etc.)
D. Accessibility from collection routes and availability of exit routes for
re-haul vehicles.
1. Expressways.
2. Major and minor streets.
E. Present and possible zoning ordinances governing Iwid use in the area
(to avoid conflict).
II. SPECIFIC AREA OF SITE(S)
A. Location should be at points where the construction and operation will
be most economical.
1. Capital outlay for land.
2. Site preparation needed before construction.
3. Proximity to utility services (e.g., gas, power, water, etc.).
B. Character of area (zoning) bordering site in relation to possible
public objection.
C. Accessibility to the specific site.
1. Major and minor streets (e.g., street widths, pavement thickness,
traffic).
D. Zoning ordinance governing land usage at the site.
E. Specific characteristics of site.
1. Spacial dimensions.
2. Existing structures.
3. Other improvements.
F. Proximity to supplementary means of transportation.
1. Water-ways.
2. Railroads.
50
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THREE VIEWS OF A SMALL CANYON PROPOSED FOR RECLAMATION
FIGURE 21
This canyon is too small
and too near a residen-
tial area for a conven-
tional fill operation
But it could be box-cut
and filled with nested
bales of refuse and
covered with earth
51
Making possible a valuable
extension of a city golf
course's present cramped
parking lot
hi Pf?u is rePr°duced at the
back of the report by a different
reproduction method to pro-ide
better detail.
-------
rather than pilot stations which by definition are temporary arrangements
designed primarily for evaluation rather than for production purposes. The
criteria for the selection of a site for the proposed pilot baling transfer
station that appear to be most relevant to this testing and validation func-
tion are: (1) avoidance of land costs by location on property presently owned
by the city, (2) minimal site preparation, (3) suitability'of site for
construction, (4) proximity to existing utility services, (5) possibility of
obtaining adequate supply of refuse materials without undue disruption of
regular collection routes and routines, (6) ease of access, and (7) prox-
imity to a Small canyon which can be filled with bales for reclamation pur-
poses. Plate 21 on page 51 shows a canyon that could be used for this pur-
pose. The possibility of future expansion of the pilot station into a full-
scale station was not overlooked, but this was not a major factor in site
selection.
Two areas were considered for the location of the proposed pilot baling trans-
fer station: (1) the general area of San Diego known as Old Town and (2) the
specific area within the boundaries of the city's Central Operations Station
at 20th and B Streets.
The Old Town area is strategically located not only in relation to the Cen-
tral collection district now served by the Arizona landfill (approximately 50
per cent of the district's collection mileage is in that area) but also' in
relation to some of the Rose Canyon operations district now served by the
Miramar landfill. In field surveys of the area several possible sites were
identified and evaluated. The project staff concluded, however, that in the
light of the criteria described above, this locale is probably better situ-
ated for a possible future full-scale baling transfer station than for a
pilot station.
The specific site, selected on city-owned property at the Central Operations
Station, is pictured in Plate 22 on page 53. Located at the foot of a steep
earth bank to the east, this site would not be visible from residential area
or from a municipal golf course to the north. Its visibility from a Naval
hospital located about a third of a mile away and at a higher elevation might
require landscape screening. It will be recalled that'the suppression of
noise was one of the important considerations in the design of the station.
Access to the proposed site is excellent. Three major highways radiating
through heavily populated areas of the city converge near the operations sta-
tion. Access to the specific site is by a road within the station. Proximity
to the Arizona landfill would permit easy re-routing of collection vehicles
in the event of emergency breakdowns at the pilot plant. Existing water,
sewer, and power lines are nearby, while lavatories and shower facilities are
within easy walking distance.
52
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U)
3
f
H
3 *9 2
Aerial view of small canyon proposed
for reclamation (upper arrow) and
proposed site for pilot station at the
Central Operations Center (lower arrow)
o
3
M
tv
K)
-------
These advantages, together with the site's proximity to a small canyon which
could be filled with baled refuse as a model reclamation project -(perhaps
leading to further exploitation of this idea in the future), appear to make
this location the best and most economical choice as a site for the proposed
pilot baling transfer station.
Basis for the Economic Feasibility Study
Actual experience with a pilot baling transfer station would undoubtedly con-
tribute to a better appraisal of the economic feasibility of a full-scale bal-
ing transfer station operation than is now possible. Nevertheless it is
prudent to make the best possible estimate, on the basis of information
presently available, of the cost of this approach to a refuse disposal prob-
lem that is becoming critical in San Diego and elsewhere, as compared with
other available alternative solutions. For a municipality that is committed
to the landfill method of refuse disposal, the basic alternatives are either
longer direct hauls to more remote landfills or the operation of transfer sta-
tions with or without an element of refuse processing, such as baling. The
refuse baling process is technically feasible and can produce greater compac-
tion than normal landfill methods. In combination with the'transfer concept
it appears to offer great promise of substantial savings. It would be futile,
however, to make the necessarily large investment in such a system if careful
and objective preliminary analysis revealed that savings could not actually
be realized in a specific situation.
The economic feasibility analysis described in the remainder DJ: this chapter
was based on data derived from a study of this city's Central Operations Sta-
tion at 20th and B Streets. This location was chosen for this purpose prima-
rily for three reasons: (1) its collection area is probably comparable to
those of the typical American city, (2) it produces substantially larger
tonnages of city-collected refuse than do either of the other two major col-
lection areas, (3) the exhaustion of its Arizona landfill, situated as it is
in the heart of the city, will present a more critical and costly situation
than will the completion of the other existing or available landfills. In
the course of the study, although it was based on localized data, certain
generalized concepts and techniques were developed which can be used to
advantage in future investigations of this kind here and elsewhere. Esti-
mated comparative costs were determined for (1) longer direct haul to the
disposal site, (2) conventional transfer station operation, and (3) baling
transfer station operation.
Data for Direct Haul Cost Study
It will be recalled that the present collection fleet at the Central Operations
Station consists of twenty-three packer trucks having twenty cubic yard capacities
and three-man crews each and one sixteen-yard, three-man packer truck which oper-
ates in the beach areas. At its other two operations stations the city has replaced
all twenty-yard, three-man packers with twenty-five-yard, two-man trucks and plans
to do so at the Central Station within a few years. The sixteen-yard vehicle will
remain in service because of the restricted street widths in the beach areas.
For purposes of this study it is assumed that these larger capacity vehicles will
be in operation by the time a full-scale baling transfer station could be con-
structed and put into operation.
54
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The factors which determine the cost of direct haul are: (l) the average
hourly cost of operating, staffing, and supervising each collection packer,
(2) the average amount of refuse transported per packer during direct haul,
(3) the average mileage traveled per packer in the direct haul, (4) the aver-
age round trip speed of a packer while hauling, and (5) the average time it
takes to complete the direct haul and return to the collection route.
Hourly Cost
As computed by the Equipment Division of the Public Works Department, cost of
operating a collection vehicle reflects depreciation, overhead, repairs, tow
calls, minor modifications, painting, fuel, overtime pay when necessary, and
standby packer trucks as needed. Normally shown as per mile unit charges in
the city's cost accounting practice, these costs were converted to charges per
hour for purposes of this study. The average equipment cost of operating a
twenty-five cubic yard packer truck for one hour was found to be $4.64.
San Diego's Sanitation Division has three classifications of collection per-
sonnel: Crewmen I, II, and III. All of these classifications perform col-
lection duties but only Crewmen II and III are authorized to drive packer
trucks. Therefore, in the twenty-five cubic yard, two-man crew arrangement,
in which the men alternate in collecting and driving, only Crewmen II and III
are assigned.. To obtain the present average hourly labor cost, it was neces-
sary to determine the average pay steps that Crewmen II and III have actually
reached. Average hourly base pay rates at these points were found to be $4.4y
and $4.72 respectively, including fringe benefits.
The hourly cost of collection supervision at the foreman level was found to be
$ 0.82 per packer including fringe benefits.
Based on these elements, the total hourly cost of operating a packer truck may
be summarized as follows:
Item Hourly Cost
Equipment - 25-yard packer $ 4.64
Labor - Crewmen II and III, including
fringe benefits
Supervision - foreman level, per packer
Total
Average Mileage and Tonnage
Average mileage traveled per packer during direct haul is the quotient of the
total mileage traveled by all packers divided by the number of packers opera-
ting. Since the present fleet of twenty-yard, three-man crew packers will be
replaced by twenty-five-yard, two-man crew trucks at the Central Operations
Station, it was necessary to determine the number of the larger vehicles that
would be needed to replace the present fleet. Records show that at the Cen-
tral Station the average amount of refuse collected and hauled is approximately
fourteen tons per day per packer, normally requiring three trips to the land-
55
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fill (occasionally four trips are necessary when the refuse contains large
proportions of bulky items which occupy more volume in the packer). The
average load on the basis of fourteen tons and three trips is U.65 tons per
packer. On the other hand, study of collection records at the Chollas Opera-
tions Station showed that on the average a twenty-five-yard packer transports
6.5 to 7 tons of refuse per trip. This average has been increasing and
Sanitation officials feel that ultimately 7«5 "tons per packer can be reached.
For purposes of determining the tonnage transported during direct haul with
the twenty-five-yard packer, it is assumed that seven tons per load is a good
average and that the amount of refuse collected per truck per day could vary
between thirteen and fifteen tons. On this basis, the twenty-yard packers at
the Central Station can be replaced with twenty-five-yard packers on a one-to-
one basis.
In order to obtain the total round trip mileage to be traveled during future
direct haul, it was necessary to determine the mileages between individual
collection routes and the proposed Murphy-Shepherd landfill to which it is
assumed Central Station packers would haul at the completion of the Arizona
landfill in 1975- For this purpose the approximate center (centroid) of each
route and the most direct haul route from that point to the landfill were
determined. Mileages were found by map measurements, checked by driving the
route by automobile. Combined daily and weekly mileages were computed for
the entire fleet. A similar procedure was used to establish the round trip
mileage for present direct haul to the Arizona landfill. The difference in
mileage between the haul to the proposed Murphy-Shepherd site and that to the
Arizona landfill is the base from which the additional cost of longer direct
haul was calculated (see Table 6. on page 57 for a summary of these mileages).
The average mileage increase in the round trip to the more remote landfill was
found to be 9-9 miles per packer.9
Average Speed and Haul Time
As part of a three-week study to determine the average speed of a packer dur-
ing direct haul, collection crews reported time and odometer readings for
(l) departure from the collection route, (2) arrival at the landfill, (3)
departure from the landfill, and (h) arrival at the collection route. The
complete round trip was recorded to take into account the difference in speed
between a loaded and an empty packer. Average speed during a complete round
trip was found to "be twenty-two miles an hour.
Average increase in haul time per packer for one round trip to the proposed
Murphy-Shepherd landfill was found to be twenty-seven minutes (by dividing
the average round trip increase of 9-9 miles by the average packer speed of
twenty-two miles an hour and multiplying this quotient by sixty minutes).
9The project staff's studies showed that, in the specific San Diego
situation examined, the break-even extra distance at which the costs
of direct haul and of a full-scale baling transfer station would be
equal was about 10.1 miles.
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TABLE 6
WEEKLY ROUNDTRIP MILEAGE INCREASE
DIRECT HAUL TO MURPHY-SHEPHERD LANDFILL VERSUS ARIZONA LANDFILL
Route
Col-
lection
Day
Mon.
Tues.
Tues.
Tues.
Wed.
Wed.
Wed.
Thurs.
Thurs.
Thurs.
Pri.
Fri.
Fri.
Number
of
Route Packers ,
Collected Required
LA PLAYA
OCEAN BEACH
LOMA PORTAL
OLD TOWN
SO. CENTER CITY
SOUTH PARK
WEST LOGAN HTS.
HILLCREST
WEST NO. PARK
MIDDLETOWN
NO. NORMAL HTS.
SO. NORMAL HTS.
EAST NO. PARK
Ik
6
1
8
8
8
6
9
7
6
8
7
6
100
Mileage
to
Murphy-
Shepherd
26.0
25-4
23-8
17.6
21.2
19-2
20.2
I6.lt
13.6
23.0
11.0
12A
12.8
Mileage
to
Arizona
16.8
19.8
15.0
9.2
6.8
4.6
8.6
5.6
k.O
9.4
6.6
5.4
3.2
Total
Mileage to
Murphy- d
Shepherd
364.0
152.4
166.6
140.8
169.6
153-6
121.2
147.6
95-2
138.0
88.0
86.8
88.8
1912.6
Total
Mileage
to d
Arizona
235.2
118.8
105.0
73-6
54.4
36.8
51.6
51-3
28.7
56.4
53-6
37-8
19.2
922.4
Total Mileage
Increase to
Murphy-Shepherd
128.8
33.6
61.6
67.2
115.2
116.8
69.6
96.3
66.5
81.6
3^.2
49.0
69.6
990. 2e
a. Four of the station's twenty-four trucks (including the 16 cubic yard packer) have special schedules
that vary from day-to-day during the week, but this does not appreciably affect the mileage figures.
b. Twenty-five cubic yard vehicle.
c. One round trip, collection route to landfill and return to route.
d. Number of packers times mileage for one round trip.
e. Average increase per packer: 990.2 7 100 = 9«9 miles.
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The Economics of Direct Haul
In standard practice, estimates of the cost of transporting quantities of
materials have been based on unit costs calculated from actual experience.
These units are usually expressed as cost per ton mile if the emphasis is on
the distance to be traveled or as cost per ton minute if the duration of the
trip is of primary importance. The distance basis is the older and more
common concept and is suitable for use when conditions of travel are rela-
tively uniform and constant. Under modern urban travel conditions encountered
in transporting municipal refuse in trucks, however, the time concept is more
appropriate. Travel to and from the disposal site may be on fast expressways,
on congested city streets, or on a combination of both. It. is quite conceiv-
able that the travel time of a refuse truck from a distant collection area to
the landfill could be less, if the route is on an expressway, than that of a
packer hauling from a closer area over city streets. Moreover., all or most
of the expense of operating refuse vehicles, consisting largely of labor costs,
is normally accounted for on a time basis or can readily be converted to it.
The standard method of computing cost per ton minute is to divide the average
total hourly cost of operating the vehicle by the average payload in tons and
to convert this quotient (cost per ton hour) into minutes by dividing by
sixty.
Cost estimates based on the ton minute unit (or on the ton mile unit) are
valid only in static situations where changes in haul time (or distance) are
not involved. Gross errors result when this approach is used, as it some-
times has been, to estimate the cost of the additional direct haul time (or
distance) required by the closing of a favorably situated landfill and the
consequent necessity of transporting to a more remote location. This common
fallacy arises from attempting to apply to a changing situation a cost unit
that is inherently a constant, and overlooking the fact that the extra time
spent on the longer haul occurs at the expense of time available for route
collection.
This point can be illustrated by a local example based on the data contained
in the preceding section of this chapter: the situation that will exist when
the Arizona landfill is completed and longer direct haul to the proposed
Murphy-Shepherd landfill "becomes necessary.
In this illustration, the basic starting point is the following "standard"
allocation of time during the working day of the collection forces:
3*4-0 minutes for actual collection (productive)
80 minutes for hauling (subsidiary)
60 minutes for early morning preparation, driving to
the route, lunch and rest breaks, and return to the
station (subsidiary)
minutes or eight hours
58
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During the actual productive time of 3^0 minutes the packer crew now collects
an average of fourteen tons of refuse. The collection rate is therefore 2^.3
minutes per ton (3*1-0 minutes divided by Ik tons) and the total daily weight
of refuse collected by a fleet of twenty-four packers is 336 tons. In the
new conditions imposed by the closing of the Arizona landfill, however, each
round trip haul would increase in distance by 9«9 miles and, in time required,
by twenty-seven minutes. With two such trips a day, the total time lost would
be fifty-four minutes, and the time available for collection would drop from
3^0 to 286 minutes (assuming that time for preparation and rest breaks would
remain constant).
At the collection rate of 24.3 minutes per ton, a packer crew would now col-
lect only 11.8 tons per day and the fleet would collect 283 tons per day
instead of the normal 336 tons. The deficit of fifty-three tons which could
not be collected in the time available would require either that the crews
work overtime or that additional packers and crews be placed in service.
Since a policy of requiring continual overtime work (in effect a permanent
lengthening of the working day) would not be a practical alternative, an
enlargement of the fleet would be required.
In these circumstances the number of additional packers required depends on
the tonnage to be collected and the daily rate of collection per packer. In
the example being considered, the addition of U.5 packers to the fleet would
be needed (53 tons divided "by 11.8 tons daily rate) or actually, since the
operation of half a truck would not be practicable, five additional packers.
The expanded fleet of twenty-nine packers would be needed to collect the
required tonnage and haul it to the new Murphy-Shepherd landfill.
In this specific case, failure to take into account the factor of lost col-
lection time would result in an error of $ 0.03 in the ton minute unit cost
and an underestimate of $70,000 in annual expenditures. The mathematics of
these serious discrepancies is shown below:
Cost Estimates Without Lost Time Correction
In the standard formula for computing ton minute unit haul costs -
Total Hourly Packer Operating Cost
Cost per Ton Minute =
60 minutes x Average Payload (tons)
substitute the appropriate data for a twenty-five cubic yard packer:
$1^.65 hourly cost, seven-ton payload:
Cost per Ton Minute = * ^ « $ 0.03^8
60 x 7
The estimated annual cost for direct haul is then obtained by multiplying the
above unit cost by the annual tonnage hauled and this product by the extra
haul time in minutes. The annual tonnage figure is 87,360 (336 daily tonnage
59
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times 260 working days in the year). By this estimate, therefore -
Annual Increased Cost » $ 0.03^8 x 87,360 tons x 27 minutes » $ 82,083.^6
Cost Estimate With Lost Time Correction
On the basis of $1^.65 per hour for operating a twenty-five cubic yard, two-
man-crew packer, the daily cost of operating (eight hour day) is $117.20 per
packer and the five additional packers required would thus cost $586* a day.
It follows that -
True Annual Increased Cost = $586. x 260 working days = $152,360
This estimated annual cost, approximately $70,000 higher than that found by
the other method, reflects the true increased cost due to increased haul time
(subsidiary work) at the expense of collection time (productive work).
The true cost per ton minute in terms of this specific situation can now be
calculated as follows:
True Cost per Ton Minute = $^2,360 annual cost increase
87,360 annual tons x 27 minutes
= $ 0.065 for 27 minutes extra haul time for
this size fleet
It is important to note that this unit cost per ton minute is not constant.
It will vary with any changes in fleet size and minutes per round trip. Al-
though this method of estimating costs has general applicability, the amount
shown relates only to the specific direct haul situation described and also
involves the assumption that the problem would be met by adding packers to the
fleet rather than by continual overtime work, which would probably be even
more costly.:
To summarize, the "standard" procedure often used for determining cost per ton
minute reflects only cost "on the road" and involves the erroneous assumption
that all other conditions will remain constant. It does not take into account
the additional costs resulting from lost collection time. In the true cost
shown above for a specific San Diego situation, this important factor has been
included in the computations.10 The annual extra cost of direct haul found in
that situation, $152,360. will be compared with the costs of two alternative
solutions of this particular problem: (l) operation of a conventional trans-
fer station and (2) operation of a baling transfer station.
See Appendix k for a presentation of the development of mathematical
formulae with general applicability to direct haul studies.
60
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Comparative Costs of Convention and Baling Transfer Stations
Conventional Transfer Stations
It is estimated that the cost of building a conventional transfer station
having a nominal capacity of 350 tons of refuse a day (the approximate weight
of refuse now being received by the Arizona Fill) would be $95,750 and the
cost of land for the site would be $1*2,360. The annual costs of amortizing
these outlays are estimated at $6,858 and $2,ll8 respectively. It is
expected that annual current expenses of operation, including re-haul to the
landfill, would be $196,630 and that the total cost for one year, including
amortization of land and capital improvements, would be $205,6o6. Details of
the estimates are shown in Table 7 on page 62.
The unit cost of this operation would be $2.26 a ton on the basis of an annual
nominal plant capacity of 91,000 tons (350 tons a day for 260 days). It
should be noted that 350 tons a day is not the optimum capacity for a conven-
tional transfer station and that this unit cost would undoubtedly be lower in
a larger station.
Baling Transfer Stations
The cost of building and equipping a baling transfer station (see Table 8 on
page 63) is estimated at $298,100 - three times as much as the capital outlay
for construction required for a conventional transfer station. Only a little
more than a third as much land is required, however, and this cost is esti-
mated at $15,000 for the baling station. Current operating expenses are
expected to be $166,698 for one year (as compared with a conventional station,
it will be noted by comparing Tables 7 and 8, plant labor and supplies and
services are higher, re-haul labor and equipment are lower, and certain types
of "housekeeping" plant equipment needed in the conventional transfer station
are not required in the baling station). As a result, current operating
expenses are almost $30,000 a year lower in the baling station than in the
conventional station. The $192,996 total cost for a year, including amorti-
zation, is about $13,000 lower.
On the basis of 91,000 tons nominal capacity (the same as for the conventional
transfer station), the gross unit cost of the baling transfer station opera-
tion would be $2.12 a ton.
Cost Comparisons
Before a legitimate comparison can be made between the estimated annual costs
of the conventional transfer station and the baling transfer station (and
between both of these and the extra cost of longer direct haul to the land-
fill), it is necessary to examine the substantial savings that can be effected
at the fill when the refuse is brought there in baled form. As shown in Table
9 on page 64,, these estimated savings amount to $35,6?2 in the specific San
Diego example being considered in this chapter.
61
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TABLE 7
ESTIMATED ANNUAL COST OF A FULL-SCALE CONVENTIONAL TRANSFER STATION
(350 TONS NOMINAL DAILY CAPACITY)
Amount
Item Total Annual*
Capital Investment Costs
1. Plant construction
300 lin. ft. Ik' high concrete retaining
wall @ $125/ft. $ 1*1,250 $ 2,163
4,800 cu. yd. embankment @ $2/yd. 9,600 480
5,000 sq. ft. 5" concrete pavement @ $-70/sq.ft. 3,500 175
30,000 sq. ft. 6" A.C. pavement @ $.60/sq. ft. 18,000 1,800
1 each 40' truck scale 12,000 1,200
950 lin. ft. 8' chain-link fence @ $12/ft 11,400 1,140
$ 95,750 $ 6,858
2. Land - 42,360 sq.ft. @ $l/s.q.ft. value 42,360 2,118
TOTAL CAPITAL INVESTMENT COSTS $138, HO $ 8,976
Current Operating Expenses
3. Plant labor
1 equipment operator III $ 10,786
1 equipment operator I 6,500
1/2 utility foreman 5,134 $22,420
4. Plant equipment
1 sweeper ($3/hr) 6,240
2 crane booms ($5/hr. - 1 standby) 20,800 27,040
5« Re-haul labor and equipment
3 heavy truck drivers 26,6lO
3 truck-tractor diesels ($5/hr) 31,200
6 sets gondola trailers ($7/hr. set) 87,360 145,170
6. Supplies and services 2,000
TOTAL CURRENT OPERATING EXPENSES $196,630
Amortization (items 1 and 2 above) 8,976
TOTAL ANNUAL COST $205,606
^Amortization computed on the basis of twenty years for land, buildings, and
earthwork and seven years for mobile equipment.
62
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TABLE 8
ESTIMATED ANNUAL COSTS OF A FULL-SCALE BALING TRANSFER STATION
(350 TONS NOMINAL DAILY CAPACITY)
Amount
Item Total Annual*
Capital Investment Costs
1. Site preparation $ 3,800 $ 350
2. Dumping pit with equipment 73,800 6,866
3. Hogger with equipment 81,800 6,551
4. Baler building with equipment 126,700 10,581
5. One 40' truck scale 12,000 1,200
$298,100 $25,548
6. Land - 15,000 sq. ft. @ $l/sq. ft. value 15,000 750
TOTAL CAPITAL INVESTMENT COSTS $313,100 $26,298
Current Operating Expenses
7. Plant labor
1 utility foreman $ 10,268
5 laborers 38,300
1 electrician (25% time) 2,600 $51,168
8. Re-haul labor and equipment
3 truck drivers $ 26,610
3 truck-tractors ($5/hr.) 31,200
6 trailers ($1.50/hr.) 18,720 $76,530
9. Supplies and services
Wire ties $ 20,000
Electrical power 15,000
Water 2,000
Miscellaneous 2,000 $39,000
TOTAL CURRENT OPERATING EXPENSES $166,698
Amortization (Items 1-6 above) 26,298
TOTAL ANNUAL COST $192,996
*Amortization computed on the basis of twenty years for building and
earthwork, fifteen years for the hogger, ten years for major
machinery (including the baler) and paving, and seven years for
mobile equipment.
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TABLE 9
ANNUAL SAVINGS IN DISPOSAL COSTS
1. Present methods of landfill operations cost an average of $0.81*2 a ton.*
2. Estimated annual cost of bale disposal:
1 mobile crane @ $5/hr
1 equipment operator III
1 equipment operator III (30$)
1 'bulldozer @ $l4/hr (30$)
1 laborer
Total
3. Cost per ton for bale disposal = $40,819
$ 10,400
10,786
3,236
8,736
7,661
$ 1*0,819
= $0.448
91,000 nominal tonnage**
4. Present disposal cost ($0.842) minus estimated bale disposal cost
($0.448) = $0.394 savings per ton, or $35,854 per year.
**350 tons per day for 260 working days in the year.
TABLE 10
COMPARATIVE ANNUAL COSTS OF CONVENTIONAL AND BALING TRANSFER STATIONS
Cost Item
1. Amortization of station
2. Amortization of land
3. Plant costs (labor and equipment)
4. Supplies and services
5- Re-haul (labor and equipment)
Total
Disposal savings at $0.39/ton (see Table 9)
Total annual net costs
Conventional
Station
$ 6,858
2,118
49,460
2,000
1^5,170
$205,606
$205,606
Baling
Station
$ 25,5^8
750
51,168
39,000
76,530
$192,996
35,672
$157,324
64
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When these savings are taken into account the estimated net annual cost of
the haling transfer station operation is reduced to $1^7,964, which is
a year lower than the cost of the conventional transfer station and
less than the cost of direct haul (see Tablem on page 64 ). The
estimated unit costs per ton are $1.63 (baling station), $2.26 (conventional
station), and $1.67 (direct haul), under these specific conditions.
Summary of the Chapter
The potential economic benefits of baling refuse can probably be fully real-
ized only in the operational setting of a transfer station. ?3ae transfer
concept, although not new, is receiving increasing attention as a means of
avoiding the expense of longer direct hauls by refuse collection vehicles to
more remote landfills when favorably located fills are exhausted. A baling
transfer station would differ from a conventional transfer station chiefly in
(l) the presence of specialized processing equipment, (2) a more sophisti-
cated system of conveying the materials from one stage to the next, and (3)
the state of the refuse at the completion of the operation.
It is proposed that a pilot baling transfer station be built and operated
under realistic production conditions in order to evaluate technical and
economic aspects of the operation. This station would cost $201,100 to build
and $127,200 to operate for a period of one year.
Economic feasibility studies based on information presently available indicate
that where the exhaustion of an existing favorably located landfill requires
longer direct haul to a more remote landfill, and when the additional round-
trip distance required per truck exceeds about 9-5 miles, a full-scale baling
transfer station would be more economical than direct hauling. In the station
capacity range studied (350 tons a day), a baling transfer station would be
substantially more economical than a conventional transfer station.
6S
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CHAPTER V
A LOOK AHEAD
The purposes of this chapter are to place in a larger frame of reference the
one-year study and investigation project which is described in the preceding
chapters of this report and to sketch briefly the follow-up study and possible
eventual action that are envisaged for the future.
As was pointed out in Chapter I, it was planned that this study would repre-
sent the first year of a possible three-year project in which the initial
study and investigation phase would be followed by a demonstration phase
involving the construction and operation of a pilot baling transfer station.
This in turn, if it proves successful, is expected to lead to practical
changes in refuse disposal practice and procedures - in effect, to a realiza-
tion of the potential benefits of refuse baling that now seem to be promised
by the initial studies.
It is believed that the two major objectives of the first phase have been met.
In the first place, as outlined in Chapter m of this report, baling municipal
refuse is physically and technically feasible in experimental situations.
This was true even when (as in the local baling operation described in that
chapter) conditions are not ideal. A pilot baling station is needed, however,
to test that feasibility under actual day-by-day production conditions with
large quantities of material. Secondly, Chapter IV provides theoretical
evidence of the economic feasibility of using this process in combination with
the transfer station concept. Here again, the experience that can be gained
with a pilot station is needed as a basis for confirming or revising present
tentative conclusions.
Beyond these major objectives the first phase of the study had certain sub-
sidiary purposes (set forth at the beginning of Chapter I) which were met with
varying degrees of comprehensiveness during the course of the project. Limi-
tations imposed by the time available and by the size of the staff prevented
the exploration of some of these in the depth that might have been desirable
or that was originally planned for the total three-year project. In other
cases the conclusions reached were tentative 1 n nature because of the -theo-
retical and experimental basis for the investigation. It may be noted that
when this study was undertaken the baling of municipal refuse was a new and
unexplored field with virtually no basis of previous experience. Some of
these areas which have not yet been fully investigated are discussed in a
later section of this chapter.
The Proposed Demonstration Project
Based on the tentative conclusions set forth in the body of this report,
construction of a pilot refuse baling transfer station is proposed in order to
demonstrate the technical and economic feasibility of the process. Prepara-
tion of design plans and specifications and construction of the facility are
scheduled for completion within nine months. During the remaining three months
66
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of the first demonstration year and throughout the second year primary
emphasis will be directed toward gathering data for evaluating the operational
and environmental effects of baling refuse.
Objectives of the Project
During the first year of demonstration and investigation, staff work will be
directed toward developing final plans and specifications for construction of
the test facility. Additional work will include preparation for plant opera-
tional procedures and staffing and development of techniques for data evalua-
tion and for investigation of environmental effects of bale disposal in
conjunction with efficient methods of bale landfill operations.
Objectives during the second year will relate to the implementation of plans
and procedures developed in the first year. The main emphasis will be: (l)
to develop and evaluate data on economics and techniques of pilot operation,
(2) to develop and evaluate techniques for efficient and effective disposal
of refuse bales, and (3) to evaluate operational and environmental effects of
baling refuse and to develop standards for comparison with conventional
transfer station and landfill operations.
Method of Procedure
Final plans and specifications for the proposed 150-tons-a-day facility will
be the responsibility of technical personnel assigned to the staff. Addi-
tional personnel from the City of San Diego's Engineering Department will be
available for special tasks as required. These special tasks will include
obtaining the engineering survey of the pilot station site, preparation of
design plans, advertising of construction bids*, awarding the contract, and
supervision of plant construction and installation of equipment. .The Public
Works and Purchasing Departments will also provide personnel for plant staff-
ing and for purchase of necessary equipment.
At the completion of station construction, tentative operational procedures
established during the design phase will be initiated. Preliminary plant
staffing will require the services of a foreman, two laborers, and a heavy
truck driver. Prior to full-capacity operation, initial trials will be
conducted to develop experience and, if required, effect correction of equip-
ment performance. Time schedules will be developed for delivery of incoming
refuse, processing of the refuse, and delivery to the disposal site. Stress
will be placed on the analysis and correction of operating problems (e.g.,
breakdowns, procedures, noise factor, dust, sanitary methods) and the develop-
ment of effective and efficient rehaul techniques (e.g., equipment, schedul-
ing, loading and unloading).
Continuing operation will provide data for developing and evaluating the
economics and techniques of the pilot operation. Emphasis will be placed on
the establishment of record keeping procedures (weights, densities, time and
motion studies, equipment performance, costs, etc.). Data will be used for
comparing the economics of a baling transfer station with direct haul and with
other transfer stations.
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Further investigation is planned in the area of developing and evaluating
techniques for effective disposal of refuse bales. Experimentation with
different types of landfill equipment and bale handling procedures will be
conducted at a selected test site. This investigation will be concerned with
the determination of landfill preparation, cover dirt and finished slope
requirements, and the feasibility of small canyon bale disposal. Supportive
cost data for evaluation purposes will be maintained.
Operational investigation will include: (l) comparing densities obtained
with shredded and unshredded refuse and with varying sizes of shredded par-
ticles, (2) determination of optimum water content to be added during baling,
(3) experimentation to find optimum length of bales, and (U) procedures for
separating ferrous metals. Technical data will be gathered for comparing and
evaluating the baling landfill environment with that of conventional land-
fills. The areas of investigation will include: (l) extent of gas production,
(2) odor production at the transfer station and in the landfill, (3) degree
of settlement or expansion, (*»•) extent of temperature rise, (5) control of
vector breeding both at the transfer station and at the landfill, and (6)
extent of water percolation. It is expected that technical data will be com-
piled over a period of several years in order to determine the long range
effects of landfilling with baled refuse.
Evaluating the Project
Plans and specifications will be reviewed and approved, construction will be
supervised during progress, and all work done and equipment furnished will be
inspected and checked against specifications, with testing where appropriate
before acceptance. Performance of the heavy equipment (hogger, baler, and
conveyors) during the operation phase of the project will be Judged on the
basis of direct observation and production and maintenance records.
The project will be evaluated on the basis of costs, compaction achieved, dust,
odor, handling and disposal problems, and on technological problems and pro-
cedures required in the refuse baling process. Special studies will be
designed (to be conducted insofar as is feasible during the course of the proj-
ect and to be followed up in the future) to evaluate the characteristics of
baled refuse in the landfill as compared to raw refuse compacted by standard
methods, with respect to decomposition, settlement, gas production, odor, and
vector breeding. The advice of professional consultants in the field of sani-
tary engineering will be utilized in setting up these studies.
During the course of the study on solid waste disposal by the refuse baling
method, the necessary information and technology will be developed and in-
cluded as part of appropriate preliminary and final reports. Conferences will
be held periodically with Federal and State officials and with private author-
ities in the field to evaluate the effectiveness of the project and for mutual
exchange of information.
68
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Areas of Special Interest
During the course of the first phase of the project certain ramifications of
the study were opened up which could not be fully explored due to limitations
of time, staff, or financial resources. Although resolution of these problem
areas was not essential to the accomplishment of the study's tvo major objec-
tives (determination of technical and economic feasibility), they are of
sufficient interest and importance to justify special consideration in this
chapter and special plans for follow-up studies in the second phase of the
project.
Factors Contributing to Bale Compaction
In Chapter III it was reported that bales of refuse produced in the factory
demonstration had markedly greater density than those produced in the local
baling test (see page 3l). In the absence of pertinent experimental evidence,
the staff theorized that this difference could be attributed primarily to the
amount of pressure applied by the two balers, to the moisture content of the
refuse, and to pre-shredding of the material used in the factory demonstration.
The known factors were the relative amounts of pressure exerted by the two
balers and a reasonable assurance that the composition of the refuse materials
baled at the two locations was not dissimilar. It was not possible, however,
either to process raw refuse in the factory baler or shredded refuse in the
local baler. At the factory, moisture content was judged (on the basis of one
sample) to be 30-0 Per cent. In the local test it was not feasible to make
accurate field measurement of moisture content. It was therefore suggested in
the report that the contribution of variable factors to compaction be deter-
mined under controlled conditions in the second phase of the study.
It should be emphasized that these uncertainties in no way invalidate the
study's basic conclusion that by baling refuse under favorable conditions it
is feasible to obtain considerably greater compaction than is obtainable by
conventional landfill methods. This was accomplished in the factory demon-
stration. The point is that accurate evaluation of all of the major contribu-
tory factors can help assure consistent realization of favorable results and
perhaps even improve them at minimum cost.
The two factors which will be emphasized in the tests during the proposed
pilot operation will be moisture content and pre-shredding, rather than compo-
sition of the refuse or pressure applied by the baler. Composition of the
refuse is expected to be reasonably constant (see Chapter II of this report).
If necessary, uniform batches will be prepared to insure uniformity for test
purposes. Baler pressure will be held constant from bale to bale. Plate 16
on page 3 6 of the report shows the general relationship between pressure and
compaction.
Moisture content of the incoming refuse varies with the season and depending
•on the amount of garbage and other wet material present. Preliminary investi-
gation indicates that the optimum moisture content is about 30 per cent and
that additional water will generally have to be applied to reach this level.
The staff believes that pre-shredding of refuse is needed to prepare the
material for more uniform absorption of the added moisture, to facilitate the
69
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movement of refuse on conveyor systems (by reducing bridging), and to present
a mechanically more homogeneous material to the baler. Pre-shredding breaks
long, tough fibers into shorter lengths and reduces paper to small pieces
which when pressed together hold the fines within the formed bale.
It is expected that in the controlled tests contemplated, with refuse composi-
tion and baler pressure held constant, optimum moisture content parameters can
be established for both raw and pre-shredded refuse. With refuse composition,
baler pressure, and water content held constant, the effect of pre-shredding
or density can be determined.
Limiting the Pilot Plant to City-collected Refuse
It was noted on page 49 of this report that the character of refuse to be
processed in the proposed baling pilot station "must be controlled due to
technical limitations of the hogger." For this reason it was planned to
process only City-collected refuse at this stage.
This approach applies only to the pilot station and not necessarily to a possi-
ble future full-scale baling transfer station. It is recognized that local
government has the responsibility of insuring that adequate disposal facilities
are available for commercially and privately transported refuse. Whether these
are publicly or privately operated and whether the facilities are identical
with, or as favorably located as, disposal sites for City-collected refuse are
matters of municipal policy. This need could conceivably be met by insuring
the continued availability of sanitary landfills for commercial and private
use, by setting up dual type transfer stations, by installing heavier-duty
(and considerably more expensive) hoggers in subsequent full-scale baling sta-
tions, or by other means.
Neither the present report nor the detailed proposals for a pilot baling sta-
tion (described in a preceding section of this chapter) are intended either to
espouse or to prejudice any particular eventual solution to the problem of
adequate refuse disposal sites for commercial and private carriers. The opera-
tional conception of a transfer station may be internal (jurisdictibnal vehi-
cles only) or external (both jurisdictional and public) or combinations thereof
(i.e., jurisdictional and large commercial haulers). Local conditions in any
City would determine the necessity of the type of transfer station service to
be provided.
Neither are the report's cost comparisons between a full-scale baling transfer
station and a conventional transfer station of the same size intended to imply
a permanent policy of restriction of input to City vehicles (see pages 61-65).
Direct haul costs were figured in terms of available cost data. Private haulers
will find different cost values for direct haul, as will other cities, when they
compute their costs. The intent of the report was to show method rather than
constant unchanging values.
In addition to the cost, however, there were certain definite considerations
that led the staff to propose limiting the pilot plant to City-collected refuse.
70
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First, as previously stated in the report, there is control over the type of
refuse coming in.
Second, during initial operation, breakdowns and mechanical difficulties can
be expected to halt production for varying lengths of time. With the proposed
location of the pilot station and with limitation to City collection vehicles,
a plant breakdown would require only a short detour to our nearby Arizona
Landfill. Since Arizona Landfill is open only to City collection forces, how-
ever, any private truck arriving at the baling station during a halt in opera-
tions would have to be detoured to Chollas or Miramar Landfills which are
approximately nine miles away.
Third, it will be possible to schedule City collection vehicles so as to insure
a smooth flow of materials, while private trucks arriving at unscheduled times
could create a supply of materials far in excess of the input storage capacity
of the plant.
Reclamation of gn»ll Canyons
In this report the feasibility of utilizing small canyons as disposal sites
for baled refuse was examined in a preliminary way. It was pointed out that
the baling process may open up this intriguing and potentially rewarding possi-
bility because (l) it would permit the use of canyons which are too small for
conventional, large-scale landfill operations and (2) it would be more accept-
able to nearby householders since with refuse in baled form the operation would
be cleaner, quieter, and less odorous.
Limited experimentation was conducted in the stacking or "nesting" of bales in
a simulated landfill situation by means of a forklift (see discussion on page
23 and pictures on pages - 24-27.) • .These tests were inconclusive because (l)
relatively few bales were disposed of in this manner, (2) since the locally
fabricated bales were not well-shaped, it was impossible to "nest" them close
together and consequently there were excessive voids between them, and (3) the
forklift was found to be an inappropriate tool for this purpose. A small can-
yon site has been selected for bale disposal during the proposed demonstration
phase of the project on a larger scale and under more realistic conditions than
were possible during the study and investigation phase Just completed. This
canyon is located on City park land near the proposed pilot baling transfer
station (see picture on page 53).
The basic operating procedure in the disposal of baled refuse in small canyons
will consist of four steps: (l) bulldozers will "brush-off" the disposal area,
(2) bulldozers will "bench" the initial area and stockpile all earth removed,
(3) a traveling crane will pick up bales deposited from the re-haul vehicle and
ne»t them in one or more layers on the levelled area, and (k) a bulldozer will
cover the nested bales with earth as required. Alternative procedures for
cover will also be investigated during the project. The basic steps outlined
above dp not include compaction since that will have been accomplished by the
baler.
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It was pointed out in Chapter I of this report that the topography of San
Diego is characterized by the presence of many large and small canyons. Most
of the larger canyons have been preempted for freeways, arterial streets, or
major drainage channels. Many of the smaller canyons are located in close
proximity to residential districts. Aot all of them are suitable or available
for baled refuse disposal sites, however, because of (l) a lack of accessi-
bility to the canyon by disposal equipment, (2) an excessive number of drain-
age structures emptying into the canyon, (3) a lack of adequate streets
feeding the area, (k) the desirability of completing neighborhood fills of
this type in a reasonably short period of time, and (5) a multiplicity of own-
erships within the canyon, making satisfactory lease or purchase negotiations
impractical.
Nevertheless, the staff's survey indicates thit approximately fifty small can-
yons would meet all of the criteria implied by these limitations and probably
could successfully be negotiated for and put into operation. All of these
fifty canyons considered suitable and available for this type of development
have certain features in common. All of them have fairly steep sides and are
in the order of eighty feet deep. Variations occur chiefly in the bottom
slope and in the width between sides. Due to these differences, they range
from 70,000 to 350,000 cubic yards in total capacity. In almost all cases a
reasonable amount of earth cover is available from the top of the canyon
sides.
Preliminary studies indicate that, because of these differences in capacity
and depending on quantities, unit disposal costs may vary markedly from can-
yon to canyon and could probably range from an estimated $0.^5 to $2.00 a ton.
It should be noted that this may be considerably more than the cost of bale
disposal in a large landfill operation (see Table 9 on page 64 ) because of
the different conditions that would be encountered in the small canyon opera-
tion and the increases in unit'costs that are inherent in a small operation.
However, the potential advantages of filling the close-in sites as well as
possible transportation savings should justify the increased costs. Firmer
estimates can be made after a basis of experience is built up during the
demonstration phase of the project.
It is estimated that the fifty suitable canyons would average about 200,000
cubic yards in capacity. The total potential capacity that could be made
available by disposing of baled refuse in small canyons, therefore, is esti-
mated at approximately 10,000,000 cubic yards - most of it favorably located
with respect to collection area centroids. Moreover, the finished fills
would create a total of approximately five hundred acres of attractive "green
belt" areas at precisely the points where they could contribute most to the
enhancement of urban living. The need for small "green areas" throughout the
City has long been recognized by planning groups, but the cost of developing
them by conventional earthfill methods has usually been prohibitive. "The
fact should not be overlooked that great benefit to the community would result
from a planned program for acquiring and developing many such areas. The
small spaces of a city are equally important, if not more so, to the people of
a community, as they are in constant everyday contact with these areas."^
The general plan for San Diego—1985; presented by the Citizens' Advisory
Committee on the General Plan.
72
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The speed of filling these small canyons would depend on the number of baling
transfer stations in operation. A 150-tons-a-day station would fill approxi-
mately ^5,000 cubic yards a year.
Summary of the Chapter
In reviewing this report and in looking ahead to the future it should be borne
in mind that the economic feasibility of baling as tentatively developed in
the study and investigation project is by no means the only or, in the long
view, the most compelling reason for constructing and operating a pilot baling
transfer station. As long as the economics appear reasonable, economics should
be considered secondary to technology. It is important, for example, to test
and evaluate, under realistic conditions, such technical aspects of refuse bal-
ing as (l) compaction obtainable, (2) optimum moisture content for effective
baling, and (3) possible hazards in bale disposal, such as gas production and
vector breeding.
It is also important to explore, under realistic conditions, the feasibility
of using bale disposal to reclaim small canyons near residential areas, where
full-scale landfill operations or the disposal of raw, unbaled refuse would
not be acceptable because of odor, dirt and noise. There are many such canyons
in San Diego, some of them situated near the centroids of refuse collection
areas.
It is believed that this new and yet untried technique may be found to have
great potential not only in conserving sanitary landfill space and reducing
direct haul distances, but also in contributing to the beautification of the
community and creating usable land for park, recreational and similar purposes.
Some of these benefits are intangible but they are no less worthwhile because
precise monetary values cannot be assigned to them.
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APPENDIX
74
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Ui
CHARACTERISTICS OF SAN DIEGO
AND SIX SELECTED CITIES OF COMPARABLE SIZE, I960
Items
Population and Housing
Total population
Population density
per square mile
Percentage of housing in
one-family units
Industry
Number manufacturing estab-
lishments of 20 or more
employees per 100,000
Number hotels, motels, tourist
courts, camps, per 100,000
Climate
Mean temperatures
January
July
Mean annual precipitation
Percentage possible sunshine
San
Diego
Boston
Buffalo
Cincin-
nati
Pitts-
"burgb.
San
Antonio
Seattle
573,22U 697A97 532,759 502,550 60^,332 537,718 557,087
2,9^ 15A57 12,869 6,569 10,968 3,966 6,810
71.1 16.U 28.3 37.1; 56.1 83.7 63.3
19.2
45.2
55.5
69.6
10 A
67
106.0
7.2
29-9
73.7
1+2.8
60
66 .k
11 A
23.5
69.8
35 e7
53
95.1
11.7
33-7
76.9
39-5
58
57-1
9-3
28.9
72.1
36,1
55
32.2
32.7
52.0
Qk.O
27.8
62
63.2
53-1
4l.2
65.6
3^.1
N.A.
I
Source: United States Bureau of the Census Reports, I960
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Appendix 2A
LETTER OF INQUIRY TO BALER MANUFACTURERS
THE CITY OF
SAN DIEGO
CITY ADMINISTRATION BUILDING • COMMUNITY CONCOURSE • SAN DIEGO • CALIFORNIA 92101
PUBLIC WORKS
DEPARTMENT
LRIC QUARTLY
DIRECTOR
213/990
August 21, 1967
Gentlemen:
Under a Federal Grant, the City of San Diego is undertaking a rather
thorough investigation of the feasibility of baling refuse as a means
of preserving our critical sanitary fill space. Refuse disposal is
recognized as a nation-wide problem and accordingly our project is
being jointly sponsored by the City of San Diego and the U. S. Depart-
ment of Health, Education and Welfare under the Solid Waste Disposal
Act. At the conclusion of our study, a detailed written report will
be prepared and printed for distribution to the Department of Health,
Education and Welfare and other cities and counties in the nation.
San Diego, like many other cities, has undergone a period of rapid
growth which is expected to continue for some time. Our present pop-
ulation of over 670,000 currently generates an estimated 350,000 tons
of solid waste refuse for disposal at our sanitary fills each year.
Over half of this refuse is municipally collected by our fleet of 65
packer trucks. Based on current projections, it is estimated that
our annual tonnage generated will have doubled to about 700>000 tons
per year by 1985- We estimate that we shall have to dispose of a
total of some 48 million tons of solid waste refuse in the next thirty
year period. The problem of finding adequate space for disposal of
this refuse by sanitary fill method is becoming an increasingly
critical one.
Our first year of study will be primarily devoted to an investigation
of the feasibility and economics of baling municipal refuse and will
76
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Page 2
August 21, 1967
Federal Grant Baling Study
include some preliminary testing of balers. For this preliminary
testing, we anticipate limiting our baling to refuse collected in
our City packer trucks (25 yard capacity), therefore no salvaging
or sorting is planned. If baling appears to be practical, we intend
to proceed with our plans to construct a pilot baling plant for more
intensive testing during the second year of our project.
We foresee several possible advantages in baling refuse :
A. Extending the life of our sanitary fills by obtaining
greater compaction.
B. Shortening or eliminating the mid-day haul to the sanitary
fill site with construction of baling/ transfer stations.
C. Possible cost reduction in handling refuse by bales.
To our knowledge, there has been very little if any experimentation
in the baling of refuse. Since this is a new and as yet unproven
application of baling equipment, we are anxious to evaluate as many
different types of balers as possible. We would appreciate any
brochures and information you may have on your baling equipment as
well as your comments or suggestions on the potential adaptability
of your equipment to the baling of municipal refuse.
Thanks in advance for your prompt attention.
very truly,
'-' K" ......... )
"iric QuarTly"
Project Director
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Appendix 2B
MAILING LIST OF BALER MANUFACTURERS
Adamson United Co.
730 Carroll Street
Akron, Ohio
Adco Manufacturing Co.
726 Gay Street
Columbus, Ohio
American Baler Co.
26kQ Ohio Street
Bellevue, Ohio
American Baler Machines Co.
839 39th Street
Brooklyn, New York
Apex Foundary Division
of Comet Industries Corp.
6lH South Eastern
Los Angeles, California
Apex Steel Corporation, Ltd.
6920 E. Slauson Avenue
Los Angeles, California
Arnold Hughes Co., Inc.
6600 Mt. Elliott Avenue
Detroit, Michigan
Baldwin-Lima-Hamilton Corp.
Eddystone Division
Philadelphia, Pennsylvania
Balemaster Division
East Chicago Machine Tool Corp.
4811 Railroad Avenue
East Chicago, Indiana
Bemis Company, Inc.
850-M Northstar Center
Minneapolis, Minnesota
Boland Machine & Mfg. Co.
1000 Tchoupitoulas Street
New Orleans, Louisiana
Boiling & Co., Inc.
3200 E. 65th Street
Cleveland, Ohio
M. E. Canfield Co.
1+19 East 3rd
Los Angeles, California
J. I. Case Co.
700 State Street
Racine, Wisconsin
Cardwell Machine Co.
19th & Franklin Streets
Richmond, Virginia
Chattanooga Welding & Machine Co.
Chestnut & 13th Streets
Chattanooga, Tennessee
Consolidated Baling Machine Co.,
ho6 Third Avenue
Brooklyn, New York
Consolidated Baling Machines
3690 South Santa Fe
Vernon, California
Cox & Sons Co.
Water £ Hampton Streets
Bridgetown, New Jersey
Dempster Bros., Inc.
Springdale Ave. & South R.R.
Khoxville, Tennessee
Dover Corporation
Elevator Division
P. 0. Box 2177
Memphis, Tennessee
Dunning & Boschert Press Co.
379 W. Water Street
Syracuse, New York
Economy Baler Co.
1032 McDonald Street .
Ann Arbor, Michigan
Galland-Henning Mfg. Co.
2761 South 31st Street
Milwaukee, Wisconsin
78
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Appendix 2B
General Hydraulics of
1*11 South Flower
Burbank, California
Calif., Inc.
Nichols Baling Presses
2646 Downey Road
Los Angeles, California
Jules D. Gratiot Co.
3423 Verdugo Road
Los Angeles, California
H-P-M Division, Koehring Co.
840 Marion Road
Mt. Gilead, Ohio
T. W. Hall Co.
59 Sunnyside Avenue
Stamford, Connecticut
Harris Press & Shear Corp.
Simmons Building
Cordele, Georgia
Harris Waste Paper Baler
4551 East Gage
Bell, California
Johnson Manufacturing Co.
P. 0. Box 311
Chippawa Falls, Wisconsin
Lake Engineering Co.
310 Gostlin Street
Hammond, Indiana
E. W. Loeser Co.
1355 Genesee Street
Buffalo, New York
Logemann Brothers Co.
3225 North Pierce Street
Milwaukee, Wisconsin
Maren Engineering Corp.
16246 School Street
South Holland, Illinois
Minnich Machine Works
1607 Ridgely Street
Baltimore, Maryland
National Balers
1071 E. 48th Street
Brooklyn, New York
Rapids Machinery Co.
875 llth Street
Marion, Iowa
Inc,
Salem-Brosius, Inc.
P. 0. Box 2222
Pittsburgh, Pennsylvania
Schick Baler Corp.
433 York Avenue
Philadelphia, Pennsylvania
Steel Equipment Co^
P. 0. Box 737-M
Cleveland, Ohio
Tamaker Corp.
6411 Ventura Boulevard
Ventura, California
Taylor-Wilson Mfg. Co.
1603 Keenan Building
Pittsburgh, Pennsylvania
Ther Electric & Machine Works
17 South Jefferson Street
Chicago, Illinois
Tonawanda Engineering Co.
Tonawanda, New York
Turner Manufacturing Co.
Statesville, North Carolina
Watson-Stillman Press Division
Farrel-Birminghara, Inc.
565 Blossom Road
Rochester, New York
Wenzelman Manufacturing Co.
1172 North Broad Street
Galesburg, Illinois
West Engineering Co.
Dill Road & Vawter
Richmond, Virginia
Inc.
79
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Appendix 3
THE AMERICAN BALER COMPANY
TELEPHONE AREA 419, 483-5790
BELLEVUE, OHIO
January 12, .1968
NOTES ON BALING TEST RUN
BY THE AMERICAN BALER CO. AT ITS PLANT
IN BELLEVUE, OHIO. TUESDAY, JANUARY 9, 1968
In view of the size of the current problem in handling solid -wastes, and
particularly the transportation and disposition of such materials, it
seems important.to analyze what can be done with existing techniques,
and to inquire into the possibility of improving these techniques either
as to capacity or results.
We arranged to send a packer truck to Louisville, Kentucky, where Mr.
Charles Bennett at the Department of Sanitation, Incinerator Plant, gra-
ciously took the time to prepare two packer loads of typical refuse. He
reports that one load was brought in from a fairly affluent section of the
town and another one from a less affluent, where the percentage of gar-
bage was relatively high. Both samples contained significant amounts
of bottles, cans and plastic containers. Measured free density of the
stock as fed to the baler was 11.4 p.c.f. In 1956, the City of Louisville
had installed a Williams Model 445 No-Knife Hog for reducing large
pieces of lumber and automobile and truck tires, etc. and the above two
loads were processed through this hog and loaded into our chartered
packer truck and brought to the plant in Bellevue. The effects of being
in the packer truck were removed by running through our shredder and
air system. At this plant we maintain.a demonstration system including
a standard model continuous heavy duty horizontal baler. This baler,
however, is equipped with a larger main hydraulic cylinder so that tests
can be run at greater pressures than normally used in collection of
secondary fibers for return to the paper mills. Plans were made for
adding water to this material. However, this proved unnecessary as the
moisture content of one sample taken at about the middle of the test was
30.0%. Four complete bales were made and measured as follows:
1. 26" x 36" x 75"
2. 26" x 36" x 78"
3. 26" x 36" x 48"
4. 26" x 36" x 71"
2,210#
2,, 490#
1, 500#
2, 125#
54.3 pcf
59.0 pcf
57.7 Dcf
55.3 pcf
80
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Then, two smaller bales were made, one of which was taken back to the
United States Public Health Service in Cincinnati by Mr. Donald A.
Oberacker, and the other was opened for inspection. A section of this
was dropped into a tank of water, and predictably floated about 92% sub-
merged. These densities were then checked on the pressure density
curve made in connection with some earlier tests in 1963, indicating the
final densities wen.' as great or greater than the more favorable of the
two curves plotted at that time. A copy is attached marked Figure 1.
One possible explanation of this is that moisture content had been lower
on the earlier test. Figures 2A and 2B show respectively the particle
size of the loose material (this can be compared with the 10-foot rule
illustrated in the circle). Figure 2B is a view of the discharge end of
the baler showing the nature of the continuous operation. Figure 3 is
a picture of the above Bale #1. Note: Corrugated end pads were used
during part, of the test, but in our opinion would not be necessary in actual
practice on a production basis with this product.
After seeing the above results and comparing these densities, it can be
safely predicted that the method can be used to produce bales of t>5 to
70 p. c. f. A baler of this type is feasible to run at a rate of up to 25 tons
per hour. Baler capacity might be pushed somewhat beyond this, but. it
is probable that two men tying the bales would find the above figure a
comfortable operating rate.
On checking the extension produced without tying the bale, the resultant
density was 45 p. c.f. If these "pads11 were removed by conveyor to
trucks or railroad cars, and loaded random., we would estimate load
density at about. 35 p.c. f. By 1500 Friday, January 12, a probe ther-
mometer in Bale #4 read 98° F. in 70° room temperature.
After the baling tests, a general discussion was held about the nature
of the equipment. Tin- shredder actually used for this test has been in
service 11 years and questions regarding maintenance cost, if any,
could be obtained directly from Mr. Bennett. Similar shredders have
been used in paper stock processing plants for over 15 years, and the
current trend in such plants is to convert to the shredder-continuous
baler method.
Preliminary discussions as to the general cost of this type of system
indicate the equipment cost for a plant to run at 50 tons an hour might
run between $125,000 to $140,000. However, no absolute predictions
are-possible because of local conditions, the'distance to proposed land-
fills, the possibility of requiring the extra density to insure the bale
81
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will sink in saltwater, and the question of how much overdesign should
be provided in the slm-dder to reduce the discipline required in elimi-
nating particularly bothersome items, for instance, heavy water heaters.
All will effect the final result. The above estimate was based on a
heavy duty shredder that would accommodate most of the usual metallic
items, but should be protected from heavy water heaters. The resultant
discipline required Tor this type of equipment would not be onerous in
any well-organized .system.
Here at American Baler we came to the conclusion that this method is
completely feasible and offers a high probability of economic success.
This conclusion is bricked up by our decision to proceed with the manu-
facture of a Model 12375 Baler, which we are prepared to guarantee to
produce 25 gross tons per hour on properly shredded material run at a
moisture rate of approximately 30%. Density will run 65 to 70 p.c.f. --
bale weight 3200# to 3500#.
THE AMERICAN BALER CO.
R. E. Seltzer
President
82
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T. le u if
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Bo 8$
83
Figure 1
-/^.^ 3
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Appendix
MATHEMATICS OF DIRECT HAUL COSTS
In Chapter IV of this report it was shown that the true cost of the extra
distance to a more remote location that refuse collection vehicles must
travel when close-in landfills are exhausted must reflect the reduction in
collection time resulting from extra time on the road (see page 60 ). Since
it is usually not practicable to compensate for this lost collection time by
constant overtime (in effect a permanent lengthening of the working day), the
number of collection vehicles must be increased.
The purpose of this appendix is to describe the mathematics of determining
the necessary fleet size (and thus the true additional cost) under the new
conditions.
First, certain constants were developed in general terms:
1. Daily collection minutes per ton =
Present collection minutes
per day per truck
Present average tons
per day per truck
n _ ., _, . ' /Present number x . . /Average daily tons
2. Daily fleet tonnage . ( ) times (
Qf
3. Daily reduced _ /Present collec- \ /Extra minutes %
~ * ' — ^-^-
_
collection time ~ * tion minutes ' — ^-^- ^of. daily haul
_ , . n . Daily reduced collection time
Long haul tons collec-
tion ability per truck ~
5. Long haul fleet size =
Daily collection minutes per ton
Daily total fleet tons (No. 2 above)
Long haul tons per truck (No. h above)
Substituting in No. f> with original values, it is found that:
Long haul fleet size equals (present number of trucks) times
(average daily tons per truck) divided by the quantity
(present collection minutes minus extra minutes of daily
haul divided by the quantity {present collection minutes per
day per truck divided by average daily tons per truck ~] )
Or:
(Present number of trucks) times (Average daily tons per truck)
Present collection minutes minus Extra minutes of daily haul
r- Present collection minutes per day per truck ~j
^- Average daily tons per truck
84
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Appendix 4
(continued)
Collecting the terms, it is found:
_, , , . , . _ Present collection
present number} (Average daily } ( minuteg }
x of trucks ' xtons per truck7 v . , J '
* per truck
/Present collection minutes minus\ , . /Average daily tons\
extra minutes of daily haul per truck
Canceling (Average daily tons per truck) the formula becomes:
Present collection minutes
Long haul Present number ,. per day per truck
j^-i j_ j = n , i times
fleet size of trucks
(Present collection minutes)
minus (Extra minutes of daily haul)
If the number of trucks factor is omitted, a simple ratio develops by which
the present fleet size may be multiplied to determine the size of the new
longer haul fleet size. Whether to round up or round down to the next higher
or lower whole truck, when a fractional truck results from the formula, is a
practical administrative decision which must take into account such factors
as fleet size, labor conditions, overtime rates, and "swing crew" policy.
To determine the true cost of the longer direct haul, multiply the annual
cost of a truck with crew by the number of extra trucks needed.
Example:
Assumptions: 30-truck present fleet carrying 15 tons per day each
7-5 tons collected per truck per trip
340 minutes collection time
18 miles addition per round trip
22 miles per hour travel speed
$30,000 annual cost per truck with crew
Computation: 18 miles @ 22 M.P.H. equals 49 minutes per trip
or 98 minutes per day lost from collection time
(30)
340 _ 42.15 (say 42) trucks needed
340 - 98 " for the longer haul
42 - 30 = 12 additional trucks
12 ($30,000) = $360,000 extra annual cost of long haul
30 (15) 260 = 117,000 annual tons to be handled
117?000°(49) = $0.0628 cost per ton/minute
85
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Appendix 5
COST OF PRE-SHREDDIWG MUNICIPAL REFUSE
The estimated pre-shredding costs presented in this Appendix include (l)
depreciation on the plant and equipment, (2) power, and (3) maintenance on
the hogger (shredder). Other elements of cost are considered to be negligi-
ble .
Estimates of maintenance costs for the hogger being considered for the pro-
posed pilot baling station are based on the experience of a present user of
the same equipment (same manufacturer and same model) for the same purpose
(shredding municipal refuse). An excerpt from a letter written on March 25,
1968, by Mr. Gerald T. Vaughn, Sr., Plant Manager of Lone Star Organics, Inc.,
Houston, Texas, in response to our inquiry, appears below:
We are grinding our total intake of 330 tons or more
per day with this shredder. It is being powered by
a 500 H.P. motor at 900 R.P.M. with a capaicty of up
to 50 tons per hour.
The hammers are removed and resurfaced every 1200 to
1500 tons, or every fourth day. There does not
appear to be a great deal of wear on the shredder
itself. Removal of the hammers and replacing with
rebuilt ones requires an average of 6 man hours - we
use a 3 mau crew for an average time of 2 hours -
this was somewhat higher before the crew learned the
proper procedure. The average resurfacing time is
about 10-12 man hours. You should be able to arrive
at some cost factors with this information using
your labor rates in the San Diego area.
Multiplying the total of 18 man hours required per 1,500 tons (6 hours to
remove and replace and 12 hours to resurface hammers) by San Diego's hourly
cost of $6.10 for this kind of work yields $109.80. Adding $U0.20 to this
for necessary materials and overhead brings the total maintenance cost to
$150 per 1,5OO tons or $0.1O a ton.
In the table on page 87 this unit cost is added to depreciation and power
costs to arrive at a total cost for pre-shredding in a pilot baling transfer
station and in a full-scale station. The only difference in capital invest-
ment needed for a full-scale station versus a pilot station is in the size of
the hogger motor, estimated to cost an additional $100 per year. The full-
scale station requires a 500 H.P. motor to process 50 tons an hour and the
pilot plant a 300 H.P. motor for a capacity of 30 tons an hour.
86
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Appendix 5
(continued)
PRE-SHREDDING COSTS IN PILOT AND FULL-SCALE BALING STATIONS
C o s t s
Per Per Per
Items Year Day Ton.
Pilot Baling Station (150 tons per day)
Depreciation
- on $50,000 for hogger, motor, and
appurtenances @ 10 years $ 5,000
- on $25,000 for building and con-
veyors @ 20 years 1,250
Power 7,000
Total $13,250 $51.00a $ 0.3^b
Maintenance (see page 86) 0.10
Total $ O.kk
Full-scale Station (350 tons per day)
Depreciation
- on $51,000 for hogger, motor, and
appurtences @ 10 years $ 5,100
- on $25,000 for building and con-
veyors @ 20 years 1,250
Power 12,000
Total $18,350 $70.58C $ 0.20d
Maintenance (see page 86) Q.IQ
Total $ 0.30
a - $13,250 divided by 260 working days in the year.
b - $ 51 divided by 150 tons.
c - $18,350 divided by 260 working days in the year.
d - $ 70.58 divided by 350 tons.
87
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SELECTED BIBLIOGRAPHY
American Public Works Association. Municipal refuse disposal. 2d ed. Chicago,
Public Administration Service, 1966. 526 p.
American Public Works Association. Refuse collection practice. 3d ed. Chicago,
Public Administration Service, 1966. 525 p.
Analysis of refuse collections and hauling operations, June—November 1958.
Pasadena, Engineering-Science, Inc., [1958], [92 p.]
Barail, L. C. Packaging engineering. New York, Reinhold Publishing Corporation,
1954. 407 p.
Bugher, R. D. Solid wastes research needs. APWA Special Report 24. Chicago,
American Public Works Association, May 1962. 80 p.
Department of Public Works. Refuse disposal site survey; [part 3]. Sacramento
County, [1966]. [89 p.]
Engineering Foundation Research Conference; Solid Waste Research and Development,
University School, Milwaukee, Wis., July 24-28, 1967. [185 p.]
Financing municipal refuse collection operations. City of San Diego, Feb. 20,
1968. 20 p.
Master plan of refuse disposal. Santa Ana, Orange County Highway Department,
1959. 58 p.
Mendoza, E. Factors in an efficient refuse collection system. Public Works,
94(1):128-129, Jan. 1963.
[Mimeographed appendix.] I_n_ The general plan for San Diego—1985; presented by
the Citizens' Advisory~~Committee on the General Plan. Adopted on March 24,
1965, by the San Diego City Planning Commission. Adopted on April 22, 1965,
by the San Diego City Council. [227 p.]
The Orange County refuse disposal program. Santa Ana, Orange County, 1965. 44 p.
Proceedings; National Conference on Solid Waste Research, University of Chicago
Center for Continuing Education, Dec. 1963. American Public Works Associ-
ation, Feb. 1964. 228 p.
-------
Pyrolysis of solid municipal wastes. City of San Diego, Feb.-1970. [35 p.]
Report on refuse collection and disposal, Los Angeles, California. [Kansas City,
Mo.], Black § Veatch, 1960. 201 p.
Size reduction of bulky metal objects by compression presses. In Day §
Zimmermann, Engineers and Architects. Special studies for~he Government
of the District of Columbia, Department of Sanitary Engineering. Public
Health Service Publication No. 1748. Washington, U.S. Government Printing
Office, 1968. p. 47-53.
Size reduction of oversize burnable waste. In Day § Zimmermann, Engineers and
Architects. Special studies for incinerators for the Government of the
District of Columbia, Department of Sanitary Engineering. Public Health
Service Publication No. 1748. Washington, U.S. Government Printing Office,
1968. p. 39-46.
Solid waste disposal study; phase one. A staff report to the Regional Solid
Waste Committee of Clinton, Eaton and Ingham Counties. Lansing, Tri-County
Regional Planning Commission, Dec. 1966. 59 p. ;.
Stern, W. The package engineering handbook. Rev. version. Chicago, Board
Products Publishing Company, [1949]. 175 p.
[The visitor industry. San Diego, Copley Press, Inc., 1962. 11 p.]
Waste management and control; a report to the Federal Council for Science and
and Technology. Publication 1400. Washington, National Academy of
Sciences—National Research Council, 1966. 257 p.
uo-374
8!
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THE FOLLOWING PAGES ARE DUPLICATES OF
ILLUSTRATIONS APPEARING ELSEWHERE IN THIS
REPORT. THEY HAVE BEEN REPRODUCED HERE BY
A DIFFERENT METHOD TO PROVIDE BETTER DETAIL.
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DESIGN AND OPERATION OF THE LOCAL TEST FACILITY
FIGURE 1
General view of
test facility
during construction
Refuse is dumped
at the upper level
A skip loader cuts
into the pile of
refuse
This page is reproduced at the
back of the report by a different
reproduction method to provide
better detail
15
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VIEWS OF LOCAL BALE DISPOSAL EXPERIMENT FIGURE 6
Hillside before
being cut to
create simulated
landfill
'
'
Fill cutting job
approaches completion
Some of the bales
are dumped on the
ground for pick-up
by the fork lift
This page is reproduced at the
back of the report by a different
reproduction method to provide
better detail.
24
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ON
II
8 8
'
rf
ff8
3 g»R
VIEW OF LOCAL BALE DISPOSAL EXPERIMENT
Stacked bales
viewed from above
M
o
oo
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COMPARISON OF RAW MATERIALS. LOCAL AND FACTORY TESTS
Unprocessed refuse was used
in the local baling tests
ro
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COMPARISON OF THE FINISHED PRODUCT
These bales were produced
San Diego's local test
B*
H
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THREE VIEWS OF A SMALL CANYON PROPOSED FOR RECLAMATION
FIGURE 21
This canyon is too small
and too near a residen-
tial area for a conven-
tional fill operation
But it could be box-cut
and filled with nested
bales of refuse and
covered with earth
Making possible a valuable
extension of a city golf
course's present cramped
parking lot
51
This page is reproduced at the
back of the report bv a different
reproduction method to provide
better detail.
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Aerial view of small canyon proposed
for reclamation (upper arrow) and
proposed site for pilot station at the
Central Operations Center (lower arrow)
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ro
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