United States Solid Waste and Policy, Planning,
Environmental Protection Emergency Response and Evaluation EPA/530-SW-89-038
Agency (OS-305) (PM-223) April 1989
Yard Waste Composting
A Study of
Eight Programs
Printed on recycled paper.
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STUDY AND ASSESSMENT OF EIGHT YARD WASTE COMPOSTING PROGRAMS
ACROSS THE UNITED STATES
Prepared by:
Alison C. Taylor
Harvard University
National Network for Environmental Policy Studies Fellow
and
Richard M. Kashmanian, Ph.D.
Project Officer
Office of Policy, Planning, and Evaluation (PM-223)
Project Funded by U.S. Environmental Protection Agency through
Fellowship Number U-913010-01-0
December 30, 1988
(rev. 2)
Copies may be obtained from:
Richard Kashmanian
Regulatory Innovations Staff (PM-223)
Office of Policy, Planning, and Evaluation
U.S. Environmental Protection Agency
401 M Street, S.W.
Washington, D.C. 20460
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Acknowledgements
Comments on previous drafts have been received from the
following representatives of the yard waste composting
programs included in this study:
Name;
M.R. "Pat" Berdan
Leo Carlson
Richard Eisinger
Robert Goldberg
Edward Go'ttko
Joseph Hayes
Pat Kennedy
John Madole
Dorran McBride
Jacob Montgomery
G. "Nick" Nicholson
Ken Shepard
Dan Slattery
Nora Smith
Affiliation:
Town of Wellesley, Massachusetts/Board
of Public Works
Pacific Topsoils, Inc., Bothell,
Washington
Composting Concepts, Inc., Afton,
Minnesota
Montgomery County, Maryland/Department
of Environmental Protection/Division of
Environmental Planning and Monitoring
Town of Westfield, New Jersey/Department
of Public Works
Woodhue Ltd., Wrightstown, New Jersey
Middlebush Compost Inc., Somerset, New
Jersey
John C. Madole Associates, St. Paul,
Minnesota
Pacific Topsoils, Inc., Bothell,
Washington
City of East Tawas, Michigan
Woodhue Ltd., Wrightstown, New Jersey
Davis Waste Removal Co., Davis,
California
City of Omaha, Nebraska/Department of
Public Works/Quality Control Division
Seattle, Washington/Solid Waste
Utility/Seattle Engineering Department
The following reviewers also provided useful comments
on previous drafts:
Name;
Ron Albrecht
Kate Cooper
Truett DeGeare
Andrew Duncan
Trisha Ferrand
Jim Glenn
Nora Goldstein
Clark Gregory
Affiliation;
Ron Albrecht Associates
Wisconsin Department of Natural
Resources/Bureau of Solid Waste
Management
U.S. EPA/Office of Solid Waste
Association of New Jersey Recyclers
Ferrand Associates
BioCvcle Magazine
BioCycle Magazine
Fulton County, Georgia Soil and Water
Conservation District
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Tapio Kuusinen
Howard Levenson
Greg Lindsay
Ron McHugh
Ellen McShane
Jeremy O'Brien
James Opaluch
Jerry Powell
Peter Strom
Todd Williams
Keith Wolff
U.S. EPA/Office of Policy, Planning and
Evaluation
U.S. Congress/Office of Technology
Assessment
Johns Hopkins University/Department of
Geography and Environmental Engineering
U.S. EPA/Office of Policy, Planning and
Evaluation
New Jersey Department of Environmental
Protection/Division of Solid Waste
Management
Public Technology, Inc.,
University of Rhode Island/Department of
Resource Economics
Resource Recycling Magazine
Rutgers University/Department of
Environmental Science
E&A Environmental Consultants
Massachusetts Department of
Environmental Quality Engineering/
Division of Solid Waste Management
11
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Table of Contents
Page
Acknowledgements . . . . . . . . i
I. Introduction i
II. Elements of the Composting Process 3
A. Oxygen 4
B. Temperature 4
C. Moisture , 5
D. Carbon/Nitrogen Ratio 5
III. Composting Technologies. . Q
A. Minimal-Level Technology Composting 7
B. Low-Level Technology Composting . 7
C. Intermediate-Level Technology Composting 8
D. High-Level Technology Composting. . . . 9
IV. Additional Considerations. 9
A. Separation and Collection Methods 9
B. Product Preparation 10
C. Marketing the Final Product 10
D. Cost and Benefits n
i. Costs 11
ii. Benefits 12
V. Composting Program Selection Criteria 12
VI. Study Approach 13
VII. Programs Selected 13
VIII. Highlights of Programs Selected „ 15
A. Davis, California 15
B. East Tawas, Michigan 16
C. Montgomery County, Maryland „ . . 17
D. Omaha, Nebraska 18
E. Seattle, Washington. 19
F* Wellesley, Massachusetts 21
G. Westfield, New Jersey 22
H. Woodbury, Minnesota 23
IX. Summary Tables 24
A. Table 1: Definitions of Yard Waste Composting
Technologies 25
B. Table 2: Background Information on Cities/County
Selected 25
111
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28
C. Table 3: Participation in Yard Waste Composting
Programs •
D. Table 4: Yard Waste Separation and Collection
Methods 28
E. Table 5: Yard Waste Composting Facilities 31
F. Table 6: Yard Waste Composting Facility
Operations 3 3
G. Table 7: Yard Waste Composting Results 35
H. Table 8: Costs and Revenues of Yard Waste
Composting 35
I. Table 9: Contact Information 41
X. Conclusions
References
Appendix A: Sample Conversion Factors.
41
43
IV
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Tables and Figures
Tables
Definitions of Composting Technologies 26
Background Information on Cities/Counties Selected 27
Participation in Yard Waste Composting Programs 29
Yard Waste Separation and Collection Methods 30
Centralized Yard Waste Composting Facilities 32
Centralized Yard Waste Composting Operations 34
Yard Waste Composting Results 36
Costs and Revenues of Yard Waste Composting 37
Contact Information 42
Figures
1: Location of the Study's Eight Yard Waste Composting
Programs 14
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I. Introduction
The United States has a municipal solid waste (MSW)
management problem of vast dimension. We are quickly running
out of places to landfill MSW (i.e., solid wastes from
primarily residential sources, as well as commercial,
institutional, and industrial sources); however, our
residents generate increasing volumes of MSW annually. We
are currently generating 160 million tons of garbage per year
with an expected increase of 20 percent by the year 2000
(U.S. EPA, 1988). At the same time, nearly one-third of the
MSW landfills in this country are expected to reach capacity
between 5 and 7 years from now (Porter, 1988), while new
landfills are difficult to site. Currently, approximately 80
percent of the MSW stream is landfilled, 10 percent is
incinerated, and 10 percent is recycled (U.S. EPA, 1988).
Administrators at all levels of government have
stressed source reduction and recycling as sound approaches
to help alleviate the increasing burden on landfills. j.
Winston Porter, Assistant Administrator for the Office of
Jolid Waste and Emergency Response at the U.S. Environmental
Protection Agency (EPA), has targeted a national goal of 25
percent source reduction and recycling by 1992, as an
important step toward reducing this burden on landfills
(Porter, 1988).
Yard wastes, i.e., debris such as grass clippings,
leaves, brush, and tree prunings, • have been estimated to
comprise approximately 18 percent of the annual national MSW
stream _ gross discards (U.S. EPA, 1988). Yard waste
generation rates and composition vary by season, year, and
region. In fact, during the peak months of their generation
(i.e., primarily during the summer and fall months), yard
wastes can represent 25-50 percent of the MSW stream.
Landfilling and incineration (or combustion in waste-
to-energy facilities) are poorly suited to the management of
leaves and grass. Since yard wastes are relatively clean,
biodegradable material, landfilling them is unnecessary and
inefficient, wasting precious landfill space. Also, their
decomposition can contribute to problems of methane gas,
acidic leachate, and settling at landfills. The seasonal
nature of yard waste generation can cause incinerators
designed to handle this type of solid waste to be over-sized
and operate inefficiently. Furthermore, the high moisture
content of this type of waste inhibits complete combustion
and results in the availability of little net usable energy
for power generation, and its burning contributes to carbon
dioxide and nitrogen oxide emissions.
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Yard wastes are often source separated and, by a
recycling process known as composting, made into a soil
amendment or mulch for use by residents, nurseries, park
services, government and private landscapers, and other
groups. Mixed into the soil as an amendment, compost can
improve the soil's physical, chemical, and biological
properties. As a mulch, compost can modify soil
temperatures, reduce erosion, control weeds, and improve
moisture retention (Rosen et al., 1988).
In addition to composting, other methods can be used to
divert yard wastes from landfills. Yard wastes, particularly
woody materials, can be ground or shredded, and perhaps
processed further, to produce a mulch. Yard wastes can also
be used as a bulking agent for other types of composting
(notably municipal sewage sludge composting) . Grass
clippings can be left as a mulch on home lawns (McCown, 1988,
1987a,b; Rosen et al. , 1988; Strom and Finstein, 1986; and'
Minnesota Extension Service—Hennepin County, undated). * In
addition, leaves can be incorporated into the soil to supply
organic matter (Prince George's County, undated). However,
since the leaves will compete with growing plants for
nitrogen, composting is the recommended approach for
preparing the material prior to incorporating it into the
soil (Flannery and Flower, 1986). These methods for managing
yard wastes can reduce the mass and volume of yard wastes by
reusing or recycling the material and can also significantly
contribute to achieving the national 25 percent source
reduction and recycling goal.
Yard waste composting has great potential as a MSW
management option in the U.S. It is estimated_that there are
between 800-1,000 yard waste composting facilities in the
nation (Glenn, 1988b) and it is expected that many more will
begin operation as the landfill situation becomes more
critical (Glenn, 1988a). As the burden on landfills across
the U.S. continues (U.S. EPA, 1988) and landfill tip fees
continue to soar (Petit, 1988), many communities are
beginning to look to yard waste composting to save landfill
capacity and landfill disposal (and related) costs, and to
produce a useful end product. In addition, several states
have already passed legislation prohibiting some or all of
their yard waste stream from disposal at landfills; for
example, New Jersey passed the Statewide. Mandatory Source
Separation and Recycling Act banning the landfilling of
leaves effective in 1988 (ANJR, 1988; State of New Jersey,
1988; Spielmann, 1988; Mattheis, 1987), and Minnesota has
qiven its Twin Cities Metropolitan area until 1990, and the
rest of the state until 1992, to come up with alternatives to
landfilling of yard wastes (State of Minnesota, 1988). Other
states and counties, as well, have passed or are proposing
similar bans (Glenn, 1988a) .
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This study looks at the methods and products of yard
waste composting in the context of 8 programs currently in
operation in the U.S., in order to provide , information and
options to communities faced with difficult choices in the
area of MSW management,,
II. Elements of the Composting Process
Composting is an aerobic (oxygen-dependent) degradation
process by which plant and other organic wastes decompose
under controlled conditions. A mass of biodegradable waste,
in' the presence of sufficient moisture and oxygen, undergoes
11 self-heat ing", a process by which microorganisms metabolize
organic matter (their food source) and release energy in the
form of heat as a by-product. The heating occurs because the
waste material also acts like an insulator, provided.the pile
is large enough. This process is nothing more than an
accelerated version of the breakdown of organic matter that
occurs under natural conditions, such as on the forest floor
(Rynk, 1987; Strom and Finstein, 1986). During the
composting process, decomposing waste generally loses between
40 and 75 percent of its original volume, although some
communities report the occurrence of even greater reductions,
before the microbes exhaust the readily available
biodegradable food supply (Massachusetts DEQE, 1986). The
reduction in weight during composting is less dramatic since
finished compost is more dense than uncompacted leaves. At
the end of the process, the compost reaches a stable state,
in which no bad odors are generated and the nutritional
content is available for plant uptake, when it is applied to
the soil. . •
Since composting is a natural process, it can be
carried out with as little, or as much, intervention and
attention as the composter desires. When practiced by
communities whose intention is to produce compost for their
own use, or for sale, the level of technology imposed on the
composting process is largely a function of the amount of
available land, labor, and capital as well as the desired end
product. Generally, yard wastes are collected and formed
into elongated piles, called windrows, which are mixed or
turned periodically to control oxygen, temperature, and odor
levels and accelerate the composting process. After some
decomposition and the desired reduction in volume occurs
and/or a certain period of time elapses, windrows are
combined to form curing piles in which the product remains
until microbial activity slows to the point where the compost
is deemed stable. Due to the potential time lag between when
finished compost is ready for distribution and the market can
accept it, the curing piles may also serve as a storage area.
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The length of time required for this entire process
varies (see discussion below and Table 7) , depending on the
composition of the yard waste stream, the size of the
windrows, the frequency of turning, and the local climate.
For example, since grass clippings contain relatively more
nitrogen than leaves, they will compost more quickly. In
addition, since grass clippings are wetter than leaves,
windrows containing grass clippings need to be turned more
frequently than those containing only leaves to avoid
anaerobic, odorous conditions. Also, composting will occur
more quickly in a warm climate than in a cool one.
Various parameters influence the composting process.
These are discussed below, with more detailed discussions
available in McCown (1988), Rosen et al. (1988), Strom and
Finstein (1986), and Royer Industries (1973), among others.
A. Oxygen
Adequate oxygen penetration into windrows (i.e., to
maintain aerobic biological conditions — oxygen levels above
5 percent are recommended by Strom and Finstein [BioCycle,
1988]) is needed for the decomposition of organic wastes,
such as yard wastes. Otherwise, anaerobic conditions can
occur, resulting in low pH levels (below 6) and generation of
malodorous compounds (Strom and Finstein, 1986), perhaps the
greatest concern of composting facilities. Frequent turning
will help to re-oxygenate the innermost region of the
windrows and hasten the composting process. When steps are
taken to accelerate the composting process (e.g., shredding
to decrease particle size and provide a greater surface area
for microorganisms to feed on), the supply of oxygen must be
increased to avoid odor generation.
B. Temperature
Internal windrow temperatures affect the rate of
composting and destruction of plant pathogens and weed seeds.
Windrow turning can keep internal temperatures between 70 and
140 degrees F, the range of temperature favorable to
composting (Strom and Finstein, 1986) . Temperatures below 70
degrees F will slow composting; temperatures above 140
degrees F for several consecutive days will kill many
desirable (i.e., feeding) microorganisms.
There is a tradeoff between oxygen supply and
temperature (which are inversely correlated and depend on
windrow size). Windrows which are too small will easily
supply oxygen to the interior of the pile, but will not
achieve sufficient temperature levels in cold weather.
Windrows which are too large will insulate their pile
interior achieving high — even excessively high—
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temperatures but impede oxygen distribution. Recommended
windrow sizes in varying circumstances are discussed below in
the section on composting technologies.
C. Moisture
Moisture is needed by microorganisms for growth;
therefore, water is a necessary ingredient to the composting
process. Leaves may need to be wetted when windrows are
initially formed (Strom and Finstein, 1986). Water may also
need to be added as windrows are turned and re-formed. Strom
and Finstein (1986) recommend moisture levels of at least 50
percent (wet weight basis). As a rough test for this
moisture level, it should be possible to squeeze a few drops
of water from a fistful of leaves. However,, excessive
moisture levels (above 60 percent) can lower internal
temperatures by inhibiting the proper oxygen flow, resulting
in odor problems.
D. Carbon/Nitrogen Ratio
Available nutrients, as gauged by the carbon/nitrogen
(C/N) ratio, represent the available food source for the
microorganisms. The higher the C/N ratio, the slower the
decomposition. In such cases, nitrogen may be added
initially, although it is usually not needed (Strom and
Finstein, 1986). If nitrogen is added, increased windrow
turning is required to maintain aerobic conditions.
Royer Industries (1973) states that decomposition
occurs most efficiently at a 30 to 1 C/N ratio. Finished
compost has a C/N ratio ranging between 10 to 1 and 20 to 1.
Compared with fresh leaves, which have a C/N ratio of 60-80
to 1, grass clippings have a ratio of 20 to 1 (Royer, 1973)
and are relatively high in moisture. As a result of their
greater supply of nitrogen, grass clippings will decompose
faster than leaves and, without an adequate oxygen supply
through frequent turning, odors will result.
Since there are typically seasonal differences in the
composition of yard wastes collected, grass clippings which
are collected in the summer can be mixed with partially
composted leaves which were collected in the fall or spring.
Adding this nitrogen source accelerates the composting of
leaves. As mentioned previously, mixed windrows need
additional turning to ensure adequate oxygenation. The ratio
of fresh grass clippings to partially composted leaves should
be less than 1 to 1, with Strom and Finstein (1986)
recommending a ratio of 1 to 3, though this may depend on
whether a high-level composting technology is used (described
.below). Recent research by university and other specialists
has involved testing finished compost for levels of lawn
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chemicals found in grass clippings, a frequently cited
concern (in addition to potential odor problems) about adding
grass to composting leaves.
In many areas of the U.S., grass clippings are
generated in greater quantities than leaves. As a result of
landfill capacity and yard waste composting concerns, several
communities and university extension specialists recommend
that homeowners let grass clippings remain on their lawns to
return valuable nutrients to the soil (e.g., McCown, 1988,
1987a,b; Rosen et al., 1988; Strom and Finstein, 1986; and
Minnesota Extension Service—Hennepin County, undated).
Brush and other woody materials have a high C/N ratio
(e.g., wood can have a 700 to 1 ratio) and decompose very
slowly. In general and depending on the end product, these
materials should not be included in windrows, but are better
handled by chipping or shredding to produce a mulch or
bedding material. The recommended diameter for woody
material to be handled in this manner is between one-quarter
inch (Rosen et al., 1988) and one inch 'McCown, 1987b and
Seattle's Solid Waste Utility and the Seattle Tilth
Association, undated).
III. Composting Technologies
Composting is a relatively easy, versatile activity
which may take place in individual backyards or in
centralized facilities operated by communities or private
companies. In this document, 4 technologies for centralized
composting are discussed: minimal-level technology; low-level
technology; intermediate-level technology; and high-level
technology. Various definitions of these terms as well as
even more advanced technologies have been presented in the
literature. The definitions for these technologies,
presented below and summarized later in Table 1, are those
developed by Strom and Finstein for leaf composting (1986;
and based on Strom's interview in BioCvcle, 1988). They are
currently researching composting with grass clippings and
will analyze different ratios of partially composted leaves
and fr«sh grass, different windrow sizes, different
composting technologies, end product quality, etc. This and
related research is in response to the lack of experience
with yard waste (i.e., leaf and grass) composting, as
compared to only leaf composting, and a reluctance by
communities to compost their annual yard waste stream,
particularly grass, due to odor, land, economic, end product,
and other concerns.
Backyard composting falls in a slightly different
category. There are probably as many types of at-home
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systems as there are people practicing home composting.
Whether performed in a simple or complex manner, backyard
composting is economically desirable because it eliminates
the costs of collection, transport, and processing which
would otherwise be paid by communities (City of Seattle,
1988; Institute for Local Self-Reliance, 1980) though they
may incur costs for supplying technical assistance and/or
materials.
A. Minimal-Level Technology Composting
Minimal-level technology composting is a very low-cost
approach to leaf management, retiring more land, but less
labor and capital, than other composting technologies.
Generally, leaves are collected and promptly piled into large
windrows which remain untouched between annual turnings. The
leaves may be wetted before they are initially formed into
windrows, but this is not essential.
Strom and Finstein (1986) note that windrows, 12 feet
high and 24 feet wide (of any length), may be formed for
minimal-level technology composting. The center of a windrow
this size will quickly become anaerobic and receive a new
oxygen supply only with each turning. An unpleasant odor
will develop in the anaerobic region and may begin to emanate
from the composting material; hence, a large land area is
necessary to buffer residents and businesses from the odor.
A quarter of a mile or more between composting windrows and
neighboring communities is recommended as an appropriate
buffer zone (Strom and Finstein, 1986). Strom and Finstein
(1986) recommend a total composting land area (not including
buffer zone) of at least 1 acre for an annual collection of
4,000 cubic yards of leaves. (The conversion factor between
cubic yards and tons [of leaves] varies depending on the
moisture content of the waste and whether it has been
compacted, but Strom and Finstein (1986) assume a. rough
average of 5 cubic yards per ton [see Appendix A for
conversion factors used by the composting facilities studied
and found in the literature].) Since rapid composting can
take place only in the presence of oxygen, the compost
normally will require 3 years to stabilize.
B. Low-Level Technology Composting
Low-level technology is the most common approach to
yard waste composting in the U.S. at this time and is well
represented among the facilities chosen for this study.
Within 1-2 days of leaf collection, low-level technology
composting calls for the material to be wetted, if necessary,
to achieve a minimum 50 percent moisture level, and
immediately formed into windrows, about 6 feet high and 12-14
feet wide. These smaller dimensions ensure that the center
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of the pile is not as isolated from the oxygen supply as it
is in the minimal-level technology approach. Windrows may
need to be (slightly) larger in cold climates to maintain
high temperatures inside the windrow during the winter months
(McCown, 1988; Mielke and Walters, 1988; and Chown, 1987).
Smaller windrows will not achieve sufficiently high
temperatures to kill pathogens and weed seeds, but
excessively large windrows can overheat, killing desirable
microorganisms and leading to anaerobic conditions.
Strom and Finstein (1986) recommend that after about 1
month, two windrows be mixed and combined into a new windrow,
approximately the same size as the initial windrows.
Additional turning is needed during the following spring and
then about every 4 months (or about 3 turnings over the
course of a year). This technology will produce a stabilized
compost in 16-18 months.
Curing piles may be formed to conserve space by
combining windrows after 10 or more months of enhanced
degradation. For a higher quality product, the compost can
be shredded and screened before marketing. Odors do not
usually pose a problem when low-level technology is used,
since the moderate size of the windrows, and the frequent
turnings, allow oxygen to reach most of the leaves, keeping
the windrow aerobic. Since the individual windrows are
smaller and hence more numerous than in the minimal-level
technology process, more land area is required for the actual
composting; however, since the potential for odor is greatly
diminished, a narrower buffer zone suffices so that the total
land area required may be smaller than for the minimal-level
technology. Strom and Finstein (1986) recommend a total land
area for composting (not including buffer zone) of about 1
acre for an annual collection of 3,000-3,500 cubic yards of
leaves.
C. Intermediate-Level Technology Composting
Strom and Finstein (BioCycle, 1988) have added this
definition to apply to those yard waste composting_facilities
which use windrow turning machines. In general, windrows are
turned on a weekly basis, and a finished compost is ready in
4-6 months. Since these machines straddle the windrows
(windrow heights' may be limited to 5 feet, though oversized
windrow turning machines allow heights up to 7 feet), these
facilities may need more than 1 acre per 3,000 cubic yards of
leaves. Though these machines are more efficient and better
windrow turners than front-end loaders, and provide greater
volume reductions (see Tables 6 and 7), the capital costs are
higher than for lower level technologies.
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D. High-Level Technology Composting
To achieve complete composting within 1 year and save
on land space for composting, Strom and Finstein (1986)
defined a practice of a high-level technology. Initially,
the leaves are wetted. Nitrogen may be added to further
accelerate the composting process. Windrows, at least 10
feet high by 20 feet wide, are then formed. They are aerated
by forced pressure blowers at the base which -are controlled
by a temperature feedback system. After composting for 2-10
weeks under these controlled, optimal conditions, the
automated system is removed. Windrows then need to be turned
periodically to achieve a finished compost within 1 year.
With frequent turning by windrow turning machines, composting
may be completed within 3-4 months. As a precaution against
release of odors during initial windrow formation, a buffer
zone similar in size to that required for low-level
technology composting is recommended by Strom and Finstein
(1986).
IV. Additional Considerations
The composting operation includes the following general
steps: (l) pre-processing; (2) processing; and (3) post-
processing. Prior to windrow formation, pre-processing steps
prepare incoming yard wastes by removing unwanted material
with manual or mechanical debagging and/or separation, and
conditioning the yard wastes by grinding, shredding, wetting,
and/or mixing. During processing, windrows are formed and
steps are taken to maintain the proper biological conditions
by shredding, mixing, and/or turning the composting material.
After the process steps are completed, the compost may need
to be shredded and/or screened to remove remaining unwanted
material and prepare the compost for distribution. A number
of considerations affect, or are involved in, the composting
operation and are discussed below.
A. Separation and Collection Methods
Composting operations vary by the manner in which yard
wastes are separated and collected, as well as the
composition of these materials. The material content of
bagged, containerized, or bulk yard wastes left at curbside
or dropped off for collection can affect the effectiveness of
the composting process. Choice of collection method(s)
depends on cost, convenience, household participation rate,
and amount and type of yard wastes separated and collected
(City of Seattle, 1988). Citizens need to be informed of the
need to keep unwanted materials out of the yard waste
collection system.
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Depending on the separation and collection methods
used, pre-processing steps may be needed. For example, non-
degradable bags need to be broken open, emptied, and perhaps
removed during collection or before windrows are initially
formed. This serves to accelerate composting and avert odor
generation. Degradable paper or plastic bags may not need to
be handled as would non-degradable bags, especially if these
bags do not impede composting; however, degradable bags may
need to be broken open. Furthermore, remaining shredded or
partially decomposed pieces of bags should be screened out of
the finished compost. An additional pre-processing step
includes grinding incoming yard wastes, especially if brush
is included, to decrease particle size and ensure that the
material is homogeneous.
B. Product Preparation
As an optional product preparation step, compost can be
coarsely shredded and screened to achieve uniform size,
remove debris, and improve its quality and appearance prior
to its distribution. As an optional final step, the compost
can be finely screened to remove virtually all remaining
debris, further improving its quality and appearance. Costs
of these optional post-processing steps should be compared to
additional benefits of selling a higher quality finished
product.
Obviously, each of these additional steps for properly
handling and processing yard wastes incurs a cost.
Descriptions and costs for various types of collection and
processing equipment are provided by the City of Seattle
(1988) and McCown (1988). Communities can be sole owners of
this equipment or share it as a cost saving measure.
C. Marketing the Final Product
When beginning a composting program, it is important to
think through the potential end uses of the finished product.
In the course of interviews with representatives from the
communities involved in this study, a number of interesting
uses and markets were found for finished compost. As seen in
Tables 7 and 8, compost has been given away or sold to
residents, used for public park service projects, sold to
private individuals, or traded for nursery stock. _ In an
innovative arrangement, Composting Concepts trades finished
compost in exchange for the use of a nursery's land for their
operation in Woodbury, Minnesota. Buyers may use compost as
a soil conditioner, in planting seedlings, as landscape
mulch, as fill, as a re-surface material for eroded parks, as
landfill cover, or for any number of other projects.
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Pat Berdan, Department of Public Works (DPW) Director
in Wellesley, Massachusetts, commented that groups need to
develop uses and markets for finished compost prior to its
production to avoid the development of an excess requiring
storage space. The issue of storage space is evident in the
composting operation of Davis Waste Removal Company (DWR) in
Davis, California. As Ken Shepard of DWR pointed out, until
additional markets and end uses are developed for their
compost, DWR will not be able to compost all types of yard
wastes generated in Davis.
D. Costs and Benefits
Assessing and comparing the costs and benefits of a
composting project or individual composting steps can
determine their net impact in economic terms. As for any
waste management practice, there are various types of costs
to consider. With respect to yard waste composting, there
are typically costs for: yard waste separation, collection,
and processing; compost storage and marketing; and
administration, public education, and technical assistance.
Benefits received from composting include: revenues received
from selling the finished compost; avoided costs from using
the finished compost as a substitute good (rather than
selling it); and avoided tip fees from not landfilling (or
incinerating) the yard wastes. These economic variables are
discussed in greater detail below.
i. Costs
Costs for composting can be grouped into capital (non-
recurring costs for administrative/legal services, land,
development/construction, buildings, and equipment) and
operation and maintenance (ongoing costs for labor, fuel,
utilities, materials, supplies, overhead, and compliance with
various requirements) (GPI, 1988). Capital costs may be
accounted for in the year of purchase or amortized (i.e.,
annualized) over the useful life of the good. In some cases,
capital and operation and maintenance costs are directly
attributed to composting or associated with rental payments
or cost contracts with a private contractor and therefore are
more easily and likely to be accounted for. In other cases,
costs may be shared with other public work operations or
communities and are therefore more difficult to estimate;
however, one way to estimate these shared costs is on a pro-
rated basis for the proportion of the item's time in use for
composting during the year. Worksheets for calculating costs
of composting and curbside recycling programs are available
in reports from Strom and Finstein (1986) and Glass Packaging
Institute (1988), respectively.
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There are also indirect costs associated with
composting. These costs are often less tangible than the
direct costs and more difficult to estimate, but should at
least be recognized in a qualitative manner. As an example,
indirect costs can include: the time spent by households in
separating their yard wastes; the impact of the separation
method on yard waste collection, the composting process, and
the value of the finished compost; and impacts by the
composting facility on the environment and neighborhood.
ii. Benefits
Benefits of composting are typically annual streams of
revenues or avoided costs. Received revenues or avoided
costs associated with selling or using the compost are a
benefit to the community mainly if the composting facility is
publicly operated. However, typically the largest economic
benefit from composting would be the avoided costs of the
alternative disposal practice, which is usually landfilling.
The most readily quantifiable short-term avoided cost
associated with diverting yard wastes from landfills is the
avoided tip fee; however, other longer-term avoided costs
include postponement of using a higher-cost replacement
facility once the present landfill closes and reduced risk of
environmental damage (Greenwood, 1988; Dunbar and Berkman,
1987) . Other costs may also be avoided or reduced by
composting, e.g., it tends to "even out" the peaks in MSW
generation and dampen the impact on the household garbage
collection cost; however, MSW management services (e.g.,
garbage collection) may be subject to contracts which are not
likely to be changed in the short run.
V. Composting Program Selection Criteria
Eight composting programs currently in operation were
selected to provide examples of the variety of designs,
management practices, and technologies which are used in yard
waste composting programs in the U.S. The selections were
made with the intention of including a diverse group of
programs representing:
o
o
o
o
diverse geographic (and climatic) regions;
rural and urban settings;
different population levels;
differing compositions
between communities,
generated and composted;
of yard waste
including yard
streams
wastes
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13
o various lengths of time for program operation;
o public or private organizations and operations, or
combinations thereof;
o various collection strategies;
o different composting technologies; and
o small and large composting capabilities.
VI. Study Approach
Journal articles and referrals from organizations
involved in composting provided a list of communities and
facilities from which to choose. After a preliminary
screening and based on the above criteria, the following
communities were chosen for this study: Davis, California/-
East Tawas, Michigan; Montgomery County, Maryland; Omaha,
Nebraska; Seattle, Washington; Wellesley, Massachusetts;
Westfield, New Jersey; and Woodbury, Minnesota. Figure 1
displays the location of each of these communities.
In keeping with resource constraints, site visits were
made to the composting facilities serving Montgomery County,
Wellesley, and Westfield; therefore, much of the information
about these 3 programs was compiled with first-hand
observation of the operations. Telephone interviews provided
information about all of the programs. Public officials .at
the community (town, city, or county) level and/or private
composting facility managers were contacted to discuss their
programs.
The contact persons for each composting program are
listed in Table 9. Also, articles or documents from which
information was extracted, and individuals who provided
program information through telephone interviews, are noted
at the end of the individual program discussions. Full
references are listed at the end of the report. A brief
overall discussion of the selected programs is followed by:
(1) sections highlighting unique features of the individual
selected programs; and (2) Tables 1-8 which contain summary
information of various design, effectiveness, and other
components of these programs with accompanying discussions.
VII. Programs Selected
The cities and county selected for this study represent
a wide range of composting operations, as outlined by the
above criteria; however, they need not necessarily be the
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, MA
Westfield, NJ
k
tontgonery County,
Figure 1: Location of the Study's Right Yard Waste Composting Programs
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biggest and/or longest standing programs. Populations of the
sponsoring communities (town, city, or county) vary from
2,600 to 633,000 people and the annual weight of yard waste
composted ranges from 116-15,600 tons.
Composting time is between 3 months and 3 years,
depending at least in part on the technology used. The
landfill tip fees faced by these cities and counties range
from $5.25-$137.00 per ton (Westfield's transfer station tip
fee) , indicating the variation across the country in the
urgency of the landfill capacity situation.
The 8 communities compost their yard wastes at a
combination of 10 centralized facilities of which 3 practice
minimal-level technology, 4 practice low-level technology, 3
practice intermediate-level technology, and none practice
high-level technology. Four of the communities also actively
promote backyard composting. Six of the 8 programs include
some form of curbside collection and 4 communities allow
private landscaping companies to drop off their collected
yard wastes at their composting facilities (typically for a
fee). Of course, private composting facilities are available
to public and private clients alike. In addition to bulk
collection, containers used for curbside pickup include:
degradable paper bags, degradable and non-degradable plastic
bags, and wheeled plastic bins. All of the programs accept
yard wastes at least during the fall and spring (by curbside
pickup or centralized drop-off). Four of the 8 programs
accept significant portions of grass for composting at their
centralized facilities.
VIII. Highlights of Programs Selected
A. Davis, California
Davis (pop. 44,000) contracts out its municipal garbage
collection (including yard waste pickup) and yard waste
composting to a private hauler, Davis Waste Removal Company
(DWR). DWR runs a separate route for yard waste collection
where, for example, homeowners rake leaves out to the curb
weekly and a device called the "Claw" (designed in Davis)
lifts the piles (which are not to exceed 5 feet X 5 feet X 5
feet) into a 32-cubic yard rear-loading packer truck for
transport to the composting facility. The Claw is a device
with "jaws" that swing open to scoop up the leaves from the
roadside. Although participation is voluntary, yard waste
pickup service has been available for over 15 years and is
accepted and utilized by residents. The city distributes
pamphlets to residents describing the benefits of composting
and techniques for curbside pickup and backyard composting.
Since yard wastes are generated year 'round in California,
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this service is available in all 4 seasons; however, there is
some variation through the year in the composition of the
yard wastes generated. For example, the yard waste stream
contains a high concentration of leaves in the fall season,
whereas grass and brush are disposed of all year.
The method used in Davis involves curbside collection
of yard wastes throughout the year and transport to their
buffered 2.5-acre composting site, followed by grinding of
the leaves with a tub grinder to accelerate the composting
process. Currently, only leaves are composted, representing
approximately 10 percent of the yard wastes picked up; bagged
grass is pulled out prior to grinding. Windrows, 6-8 feet
high by 10 feet wide, are then formed and turned every 2
weeks with a front-end loader. The warm climate of
California accelerates the composting and the product is
ready in 3-4 months, although the composting process may not
be completed.
DWR does not currently have a commercial market for
their compost, so city residents are allowed to use it at no
charge as a soil amendment in the community garden. The main
motivation behind composting is environmental concern rather
than economic gain, as Davis does not currently face the high
landfill tip fees seen in other parts of the country. Ken
Shepard of DWR explained that grass and brush will not be
composted until a market is found for the end product,
because these additional components would cause the volume of
compost produced to far exceed the community gardening
demand. Shepard also pointed out that some exotic components
(such as eucalyptus leaves) go into the compost in
California, and these materials may shift the pH out of the
range in which plants will grow well. If marketed, the
finished product would need to be monitored carefully to
ensure consistent quality.
References: Gertman, 1988; Shepard, 1988; Metrocenter YMCA,
1987; Gertman, 1985; City of Davis, undated
B. East Tawas, Michigan
East Tawas (pop. 2,600) was the smallest community
chosen for this study, and serves as an example of how
composting may be incorporated into the activities of a small
town's DPW. In 1986, the town received a $20,000 grant from
the Clean Michigan Fund with which they bought a front-end
loader to mix and turn their windrows, which are 4 feet high
and 8 feet wide. No additional labor was hired by the town
when composting activity began.
Yard wastes are centrally composted at the site of an
old covered landfill, using 2.5 acres of the 40-acre site.
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Composting also takes place in the yards of a few residents
who produce their own mulch by backyard composting. Leaves,
grass, and brush are delivered to the composting facility in
two ways: 1) separate curbside collection of the bagged yard
wastes in the fall and spring seasons; and 2) drop-off by
residents, who are allowed to borrow a key to the composting
area for this purpose. The collected bags are opened by town
crews and checked for garbage which is then removed. These
crews also form the windrows and turn them when their normal
work is slow.
East Tawas does not currently shred or grind leaves or
grass as part of their composting process; however, brush is
chipped and used as a road base in a swampy area. City
manager Jacob Montgomery estimates that the participation
rate in the pickup program is 70 percent. Currently, the
finished compost is used by the city's park service for
planting trees and regenerating flower beds.
References: Montgomery, 1988; Logsdon, 1987
C. Montgomery County, Maryland
Montgomery County (pop. 633,000) is the most heavily
populated community included in this study; however, the
program currently serves nearly one-half of the county's
households. The entire program is administered by the
county's Department of Environmental Protection.
Responsibility for curbside leaf collection (and drop-off at
the transfer stations) belongs to the county's Department of
Transportation. Leaf-loader vacuums have been used to pick
up (and partially shred) leaves for composting since 1984.
The same trucks that push the snowplows in winter are used to
pull the curbside vacuums on their route twice in the fall
and once In the spring. The curbside collection program has
received an excellent response from residents who participate
voluntarily by raking leaves to their curbsides. Residents
are informed of the scheduled collection route by notices
which are posted on trees and telephone poles in each
neighborhood. The county discourages residents from bagging
leaves prior to pickup, but some plastic bags are put out at
curbside and these are broken open prior to vacuuming.
The composting facility is located in the town of
Dickerson which is in the western part of the county. The
facility lies within 270 acres of county-owned land and
consists of a 47-acre asphalt pad and 3 sedimentation ponds
to collect runoff. It was originally built for composting
municipal sewage sludge and was switched to leaf composting
in 1984. Responsibility for hauling the leaves from the
transfer stations to the compost facility, operating the
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compost facility, and selling the finished compost rests with
a private contractor.
The only reported problem with this facility is the
tendency of soil to erode from around the sedimentation
ponds, as a result of runoff from the asphalt pad during
heavy rains. The contents of the ponds are monitored
regularly for compliance with the facility's surface water
discharge permit, and are consistently found to comply. A
double fence surrounds the facility to prevent the wind from
carrying plastic debris off-site.
Windrows, 6 feet high by 12-15 feet wide, are formed,
and then shredded, aerated, and turned monthly with a roto-
shredder. Water is not added during the composting process
since rainfall provides sufficient moisture. The compost is
shredded and screened to remove contaminants which include
shredded plastic bags, tennis balls, and brush. Composting
of leaves presently takes between 6 and 12 months, depending
on whether the leaves are collected in the fall or spring.
Since finished compost is more likely to be sold during
spring than fall, it may need to be stored on-site for 6
months. The finished compost is sold in loads of 10 cubic
yards or more, primarily to landscapers and nurseries as a
soil amendment.
At present, Montgomery County is pilot-testing
combining grass and partially composted leaves in various
proportions. This addition of grass will increase the
required frequency of turning, but it is hoped that it will
also speed up the composting process. The finished compost
will be tested for heavy metals, weed seeds, residual
herbicides, and pesticide levels before a final decision is
made on composting grass with leaves.
References: Goldberg, 1988; Spielmann, 1988; Wagaman, 1988;
Franklin Associates, 1987
D. Omaha, Nebraska
Omaha (pop. 350,000) operates a yard waste composting
program in which grass clippings are composted along with
leaves. Dan Slattery of the Department of Public Works
estimates that 60 percent of the yard wastes composted in
Omaha consist of grass. Yard wastes are also accepted from
lawn service companies but are turned away if• t™** tc{*•
contaminated with, e.g., tree stumps, rocks, PVC Pipe, lawn
mower handles, or tires. Partially composted and fresh grass
are mixed by tub grinder with newly received leaves and tree
SLSSs and then wetted. Grinding this material decreases
particle size to a maximum diameter of one-tenth inch,
reduces yard waste volume, aerates the composting material,
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and accelerates composting. A front-end loader (shared with
the county) piles the material into windrows, 6 feet high by
12-15 feet wide, which are left until the following year when
they are turned.
The biggest concern of most facilities that refuse to
compost grass is the odor generated as it decomposes
(discussed earlier and in Strom and Finstein, 1986); however,
Omaha has not experienced a problem with odor complaints from
the public (except infrequently from lawn service companies
at drop-off) due to their facility's remote location, wide
buffer zone (the 2-acre facility is at the 80-acre county
landfill), and relatively small operation. It is reported
that odors are not a problem for workers at the facility
either._ Odors are strong when material is ground in November
which is the only time during the composting process that
these windrows are turned, but the buffer zone .protects
residents from being affected by the operation.
Currently, just. 3 subdivisions of the city (or
approximately 1 percent of its population) are involved in
the program; however, Omaha looks forward to expanding this
program. The finished compost is used by the county (whose
land is used for the operation) as a substitute for landfill
topsoil and a soil amendment at county parks.
An interesting aspect of Omaha's program is the
container in which homeowners leave yard wastes for pickup.
Residents rent 90-gallon plastic yard waste bins or carts
(from the city for $12 per year) which can be wheeled to the
curb. A special hoist lifts and dumps the yard waste bins
into the packer trucks used for collection and returns them
to the sidewalk for reuse. No shredding takes place in this
step. Initially, the bins were susceptible to being crushed
by the hoist because it was lifting at an excessive speed.
To solve the problem, a control was installed on the trucks
to limit the speed of lifting, and also the structure of the
carts was reinforced by their manufacturer (without charge).
This year, Omaha has distributed 5,000 free degradable
cornstarch plastic bags with instructions to households that
they should only be used when the carts are full.
References: Slattery, 1988; Spielmann, 1988
E. Seattle, Washington
Seattle (pop. 500,000), the second largest community
included in this study, has developed a multi-faceted
approach to yard waste composting, including: 1) public
education and encouragement for backyard composters; 2)
special "Clean Green" hours at the transfer stations during
which residents may leave yard wastes for a discounted
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disposal fee; and (3) plans to implement curbside collection
of yard wastes in 1989. In addition to the _economic
incentive for composting yard wastes, Seattle is dedicated to
composting out of concern for the environment.
Pacific Topsoils, Inc., a private composting facility,
accepts Seattle's yard wastes for $22.50 per ton, whereas the
landfill, which is closer to the transfer stations, charges
$31.50 per ton. Six acres of Pacific Topsoils1 34 acres
(including buffer) are devoted to its composting operation.
The facility accepts yard wastes from at least 6 cities,
either by direct contract with the cities or their contract
haulers. Incoming yard wastes are visually inspected for
plastics, rocks, etc. and then processed by grinding to
accelerate the composting process. The yard wastes are then
placed in piles, 25 feet high and 40 feet wide, which are not
subsequently turned. Screening is used to prepare the
compost for distribution. Material which does not pass
through the screen, i.e., oversized, not fully composted
material, is returned to the piles. The compost is
supplemented with organic matter and other amendments and
sold as a topsoil primarily to landscapers. The quality of
the finished compost depends on that desired by the buyer.
The community composting education program offers
training to 25 volunteer "master composters" each year who in
turn instruct others in backyard composting techniques.
Seattle has constructed 4 demonstration sites where up to 16
different composting methods are on display for residents who
want to look and learn. In 1989, Seattle will also supply
backyard composting bins to approximately 1,100 households
involved in an expanded version of this program. As an
additional financial incentive, households which backyard
compost avoid a $2 per month fee for curbside yard waste
collection.
Seattle's program is apparently becoming stronger as
both the city and residents increase efforts to promote
composting programs. In 1989, the "Clean Green" hours at
the transfer stations have been extended to include all hours
of station operation. A consultant's survey performed for
the Seattle Solid Waste Utility (City of Seattle, 1988)
suggests the following improvements to the composting effort:
(1) that 17,000 tons, or 18.5 percent of the city's yard
wastes generated, be composted in the backyards of 30 percent
of Seattle's households; and (2) that 51,700 tons, or 56.5
percent of the yard wastes generated by Seattle's population,
be composted centrally. These two programs would divert
68,700 tons, or 75 percent of the city's yard wastes from the
landfill.
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References: Carlson, 1988; McBride, 1988; Smith, 1988;
Watson, 1987a,b
F. Wellesley, Massachusetts
Wellesley (pop. 27,000), too, has more than 1 method
for diverting yard wastes from their landfill. Wellesley
encourages backyard composting, allows residents to drop off
yard wastes in a centralized location, and runs a special
drop-off program for private landscapers and others in the
lawn service business who collect leaves. The encouragement
of backyard composting and the drop-off area for residents
are part of an extensive community recycling agenda.
Wellesley provides its citizens with the opportunity to
recycle many elements of the solid waste stream, from cans to
books to wood waste, in a 90-acre landscaped area known as
the RDF (Recycling and Disposal Facility) at its transfer
station. Residents stop at appropriate areas to deposit
specific items as they drive through the RDF. The
residential yard wastes are composted on a 1.5-acre site by
minimal-level technology at the RDF and the finished product
is available for use in residents' gardens and yards, with
the Remainder being traded to a nursery for merchandise
credit. Yard wastes are formed into a large windrow, 10 feet
high by 30 feet wide, with a front-end loader and bulldozer
which are also used to turn the windrow about once per year.
Water is not added to the windrow. Wellesley has found that
residents are much more interested in the finished product at
the RDF if it has been screened, but there is not always time
and manpower for this task. Use of a tub grinder to shred
brush is currently being considered.
The composting of landscapers1 leaves takes place on a
1-acre area (with a minimum 50-foot buffer) in the DPW yard.
Landscapers pay $200 per vehicle for a permit to dump truck
loads of leaves, and may continue to drop off leaves until
the composting area is full for the season. These permits
can be taken away if incoming loads are determined to be
contaminated. The leaves collected in this program are
composted using low-level technology. A front-end loader is
used to turn the windrows once per month. After 1 year, the
compost is moved into a curing pile and screened. The
finished product is used as a soil amendment or conditioner
by the town in planting and landscaping projects.
Wellesley aggressively supports and encourages home
composting practices; in fact, according to a survey, 39
percent of the residents reported that they compost in their
backyards. However, in the past the town's approach met
resistance from Massachusetts' state government. In an
effort to encourage home composters, the town circulated
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information suggesting that fallen fruit and vegetable
debris from backyard gardens be incorporated in compost
piles of grass and leaves. The Massachusetts Department of
Health contacted Wellesley and informed the town that
composting food wastes is against regulations. DPW Director,
Pat Berdan, would like to see more unity among different
levels of government on goals of recycling and composting.
References: Berdan, 1988, 1987; Metrocenter YMCA, 1987;
Wellesley DPW, undated
G. Westfield, New Jersey
From the early 1970's until 1987, Westfield (pop.
30,000) composted its leaves at the town conservation center.
Due to large increases in volume, Westfield now uses a
combination of private operations to compost yard wastes in
compliance with New Jersey's mandatory composting requirement
(i.e., the ban on landfilling leaves). Although the town
does not provide pickup services for general MSW, 3 rounds of
leaf pickup from town curbsides are performed each year by
front-end loaders and dump trucks. Residents, alerted by
mailings and advertisements, rake their leaves to the curb on
the appropriate days. Leaves mixed together with household
trash will not be picked up by the privately contracted
garbage haulers. Residents may also separate and drop off
their grass and brush for a fee at the town's conservation
center where it is collected for transport.
During 1988, the town transported all collected yard
wastes to one of three private composting (or, in the case of
brush, shredding) facilities: 1,730 tons of leaves to
Middlebush Compost Inc. for composting; 1,400 tons of grass
clippings to Woodhue Ltd. for composting; and 1,423 tons of
tree trimmings and brush to Alternate Disposal Systems Inc.
for shredding. These facilities also accept yard wastes from
other communities in New Jersey. In fact, Middlebush Compost
has recently been the object of pressure (from county
residents) to close, because they accept leaves from outside
the county.
Middlebush Compost is located on a 25-acre site
(including a 150-foot buffer surrounding residential areas),
of which 15 acres are used for composting leaves from
approximately 10-12 New Jersey communities (including a few
served by contract haulers). A large windrow turning machine
is used to form windrows, 7 feet high by 16-18 feet wide,
after shredding, aerating, and fluffing the material.
Middlebush Compost is currently investigating a modification
in its state solid waste facility permit to allow it to also
compost grass clippings. The finished compost is sold as a
soil amendment, mulch, or potting soil for $25 per ton.
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Woodhue Ltd. is the site of a privately run 126-acre
farm, which also operates a 4.5-acre yard waste composting
facility under a solid waste permit issued by the state of
New Jersey. In 1988, Woodhue accepted grass clippings from
Westfield and 2 other communities and mixed them at a 1 to 2
ratio with partially composted leaves received from
approximately 10 other communities. A windrow turning
machine is used to shred, aerate, and fluff the composting
yard wastes and to re-form windrows, 6 feet high by 12 feet
wide. Only 1 odor complaint has been received since Woodhue
began composting in October 1986. Between 12 and 25 percent
of the total incoming yard debris (the highest among the
composting facilities studied) is reject material, i.e., non-
compostable material, and disposed of in a landfill. This
relatively high percent of rejects is influenced heavily by
the community's source separation, collection, and street-
cleaning procedures. The finished compost is screened,
tested (for pH, heavy metals, and toxicity), and then field-
applied on-site as a soil amendment and fertilizer supplement
(but not a fertilizer) to save ($35-65 per acre) on the
amount of fertilizer used.
Yard waste generation and composting activity,
participation rates, and other general data presented in the
summary tables refer specifically to the town of Westfield;
however, the composting processes are reported as described
by the private composting facilities for all of their yard
wastes received. Westfield faces the steepest landfill tip
fee of any community in this study at $137 per ton (at the
transfer station); hence, there is a strong financial
incentive to comply with New Jersey's Statewide Mandatory
Source Separation and Recycling Act.
References: ANJR, 1988; Gottko, 1988; Hayes, 1988; Kennedy,
1988; Nicholson, 1988; Strom et al., 1986; Derr,
1985
H. Woodbury, Minnesota
Woodbury's (pop. 13,520) yard wastes are collected and
composted by Composting Concepts. When the program began in
April 1987, bags were provided free of charge as an incentive
to residents to participate in the yard waste composting
program. Degradable paper bags are preferred by waste
haulers since they eliminate the need for manual debagging or
purchasing special debagging or shredding equipment. Workers
load the bags into packer trucks which are also used for
regular garbage pickup. Use of the degradable paper bags was
discontinued by Composting Concepts because most residents
opted to buy regular plastic bags rather than use the free
paper bags and debagging costs were therefore still incurred.
Composting Concepts also sells cornstarch plastic bags which
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are claimed to degrade in 4 months. Since the leaves require
a 12-month composting period, the bags are not expected to
hinder the process. These bags are recognized during yard
waste collection by their distinct color and insignia which
distinguishes them from bags of household garbage set out at
curbside.
Windrows, 5 feet high and 15 feet wide, are initially
formed using a front-end loader. Later, to prepare for
winter, the material is wetted and then three windrows are
combined into one, 12-15 feet high and 25 feet wide. After
winter, the windrows are turned once each month. Composting
Concepts exchanges finished compost with Bailey Nursery as a
soil amendment in return for the use of 2 acres for
composting at the nursery's 500-acre site. The facility
operates subject to a local land use permit and is required
of commercial activities around Woodbury.
Minnesota Extension Service—Hennepin County has
written and distributed brochures encouraging residents to
leave grass clippings on their lawns rather than raking and
bagging them and to also compost in their backyards. These
management methods might be very effective in reducing the
volume of yard wastes to be collected and centrally
composted, thereby saving on community collection,
transportation, and composting costs.
Yard waste composting is currently mandatory in 4 of
the 18 communities served by Composting Concepts. Although
composting is not currently mandatory in Woodbury, the town
is getting a head start now, with the knowledge that
Minnesota has passed legislation that will make yard waste
composting mandatory in the Twin Cities Metropolitan area by
1990 and for the rest of the state by 1992.
References: Eisinger, 1988; Madole, 1988a,b; State of
Minnesota, 1988; Minnesota Extension Service—
Hennepin County, undated
IX. Summary Tables
In this study, a community (town, city, or county)
perspective, rather than a facility perspective, has been
taken. Therefore, where a community has more than 1 way of
diverting its yard wastes from disposal in a landfill (e.g.,
some combination of a publicly operated facility, backyard
programs, and/or a privately operated facility), every effort
has been made to present information on all facets of the
program. However, information about the number of households
served, level of household participation, etc., when there is
more than 1 method of yard waste collection (curbside or
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drop-off) or more than 1 method of yard waste composting
(backyard or centralized), is not separated out.
Some of the data for these individual programs are
presented on separate lines in the tables (e.g., Westfield) .
This separation leads to some difficulty in accurately
presenting such items as operation costs and land area used
for composting. Land area devoted to composting at private
facilities is used to compost yard wastes from several
communities, not just those included in this study.
Furthermore, some of the operations described are
well-established or independent of other community functions;
therefore, city or county officials have an excellent idea of
the annual costs of the program. Others have recently
incurred start-up costs for equipment which must be amortized
across an expected service life, or simply are not yet
operating efficiently or at capacity. In some cases, costs
are embedded in the budget allotted for more than one DPW
project.
In all cases, every effort has been made to provide
detailed, accurate data and information, as displayed in
Tables 1-9. Definitions of yard composting technologies ' as
defined by Strom and Finstein (1986) are listed in Table 1.
Background information about the 8 communities included and
their yard waste composting programs is provided in Tables 2-
4. Data pertaining to the composting facilities and their
effectiveness are shown in Tables 5-7. Cost comparisons of
composting versus landfilling for each community are given in
Table 8. Contact names are listed in Table 9.
A. Table 1: Definitions of Yard Waste Composting
Technologies
As discussed above, Strom and Finstein (1986, and
BioCvcle interview in 1988) defined 4 levels of technology
for yard waste composting: minimal, low, intermediate, and
high. Except for the high-level technology, each of these
technologies is used in at least 1 of the composting
facilities included in this study.
B. Table 2: Background Information on Cities/County
Selected
General background information for the 8 communities
selected is shown in Table 2. The communities are spread
across the country: 3 are in eastern states, 3 are in central
states, and 2 are in western states. No community selected
is located further south than Davis, California. Communities
and state agencies were contacted as far south as Florida,
but attempts to uncover active yard waste composting programs
were unsuccessful. As indicated, there is a wide range of
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26
Table 1: Definitions of Yard Waste Composting Technologies
Technology Type Turning Frequency Windrow Size
Minimal-level
Low-level
Intermediate-level
High-level
Once/year
3-5 times/year
Once/week with windrow
turning machine
First 2-10 weeks with
automated system,
turned periodically
thereafter
12' high x 24' wide
6' high x 12'-14' wide
5'-7' high x 10'-14' wide
10' high x 20' wide,
initially
Sources: Strom and Finstein, 1986 and Strom interview in BioCycle, 1988.
-------
27
Table 2: Background Information on Cities/County Selected
City or
County
Davis (c)
East Tawas
Mont. Co. (e)
'Omaha
Seattle (c)
Wellesley
Westfield
Woodbury
Notes:
State
CA
Ml
MD
NB
WA
MA
NJ
MN
(a) U
Density
(a)
U/S
R
U/S/R
U/S
U/S
S/R
U/S
U/S
- urban,
Total Total Total Yard Yard Wastes Composition of Total Yard
City/ Households Waste Stream as % of Waste Stream (% weight)
County (tons/yr) MSW [Leaves |Grass jBrush |Other
Population Stream (b)
44,000
2,600
633,000
350,000
500,000
27,000
30,000
13,520
S - suburban
10,000
1,350
244,000
100,000
229,000
8,500
10,400
4,790
, R - rural
5,475
350
110,000
48,000
92,000
8,000
n/a
1,092 (f)
25
10 (d)
19
33 (d)
. 12
28
n/a
18 (f)
n/a n/a n/a n/a
50 5 45 n/a
40 35 5 25 n/a
n/a n/a n/a n/a
20 33 25 22
50 31 19 n/a
n/a n/a n/a n/a
36 64 (f) n/a
(b) includes garden material, weeds, sod, dirt, etc.
(c) estimate of total yard waste stream does not include amount generated
and collected by lawn service companies and public work crews
(d) yard wastes are estimated as percent of residential solid waste stream
(e) population and household estimates based on 1986
(f) yard waste estimate does not include brush
n/a: not available
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28
community sizes, population densities, and yard waste
characteristics among the communities selected. In addition,
the reported share of yard wastes as a percentage of the
total MSW stream gross discards for these communities (i.e.,
those which reported total yard wastes as a. percent of their
MSW stream) ranges from 12-28 percent. However, total yard
waste stream estimates for Davis and Seattle may be
underestimated because yard wastes generated and collected by
lawn service companies and public crews are not included. An
estimate of the average percent share of yard wastes in the
MSW stream for these communities is 15 percent, approximately
the same as EPA's (1988) national average estimate.
C. Table 3: Participation in Yard Waste Composting
Programs
The scope of the composting programs studied is
presented in Table 3. Most of these composting programs,
backyard or centralized (which use curbside pickup and/or
resident drop-off) , extend to all households in the
communities, while some programs included may currently be
targeted to specific areas in the community. Household
participation rates are estimated based on a community's
entire composting program, including any combination of
backyard and centralized composting activities.
Participation of households served is high,, averaging around
80 percent; however, the percent of total yard wastes
composted is not as high. Reasons for this include: (1) the
fact that not all households are served by the composting
programs; (2) the variation in the composition of these
communities' yard wastes and the percentage of each type of
material being composted; (3) the inconsistent participation
of some households; and (4) the uneven generation and
composition of yard wastes across households.
D. Table 4: Yard Waste Separation and Collection
Methods
As indicated in Table 4, some communities give
residents 2 options for composting their yard wastes:
backyard composting; or source separation followed by
centralized composting, i.e., separating yard wastes from
other solid wastes for curbside pickup and transport by the
community to, or self-haul and drop-off by the household at,
a composting facility or transfer facility. Separation and
collection methods chosen by these communities will depend on
convenience, costs, and amount of yard debris which can be
diverted from landfills. Only 1 of the composting programs
(Westfield's) has mandatory source separation of yard wastes
(requiring that leaves be separated from household garbage
prior to curbside pickup). As a result, Westfield claims
that 100 percent of its leaves are handled by composting; in
-------
29
Table 3: Participation in Yard Waste Composting Programs
City or State Startup Total Total % of
County Year Population Households Household!
of Served Served Served
Program
Davis CA 1981 44,000 10,000 100
East Tawas Ml 1984 2,600 1,350 100
Montgomery Co. MD 1984 282,000 75,000 48
Omaha MB 1987 3,735 830 1
Seattle (e) WA 1987 500,000 229,000 100
Wellesley MA 1969 27,000 8,500 100
Westfield NJ 1970 30,000 10,400 100
Participation Total Yard % of Total Year
s of Households Waste Yard Waste of
Served (%) Composted Composted Data
(a) (tons/yr) (c)
(b) (c)
70 - 80 500 9 1 987
70 138 (d) 39 (d) 1987
90 - 95 15,600 1 4 1987
66 500 1 1988
n/a 3,600 4 1988
90 - 95 6,500 81 1 987/
1988
100: 25 (f) 3,130 (d) n/a -1 987/
1988
Woodbury
Notes:
MN 1987
2,329
825
17
80
•116 11 (d) 1987
(a) estimated by local officials
(b) reported as % of the total yard waste stream of the city or county currently
being composted
(c) does not include amount backyard composted
(d) does not include amount of brush chipped or shredded
(e) although 100% of households are served, the program is not yet in full swing
(f) participation rate was 100% for curbside collection of leaves and 25% for
drop-off of grass and brush with the remaining households having their grass
backyard composted or picked up by landscaping services
n/a: not available
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30
Table 4: Yard Waste Separation and Collection Methods
City or
County
Davis
State Mandatory
Program?
(Y/N)
CA N
N
Collection
Method
(a)
backyard
curbside - claw
Frequency
of
Collection
(b)
n/a
1 /week
Collection
Seasons
(b)
Sp,Su,F,W
Sp.Su.F.W
Means of Raising
Awareness and Support
for the Program
in the Community
public ed
public ed
East Tawas
Montgomery Co.
Omaha
Seattle
Wellesley
Westfield
Woodbury
Notes:
Ml
MD
WA
MA
NJ
MN
N
N
N
N
N
N
N
N
N
Y
Y
Y
N
curbside - plastic bag 1/week
resident drop-off
Sp,F
curbside - vacuum 1/Sp,2/F Sp,F
Sp.Su.F
n/a Sp.Su.F
curbside - wheeled bin 1/week
and degradable bag
landscaper drop-off
newspaper ad
pickup schedule signs
neighborhood assoc
backyard
resident drop-off
landscaper drop-off
backyard
resident drop-off
landscaper drop-off
curbside - front loadei
resident drop-off
landscaper drop-off
backyard
curbside - degrad.bag 1/week
n/a
n/a
n/a
n/a
n/a
n/a
2/F
n/a
n/a
/week
Sp.Su.F.W
Sp.Su.F.W
Sp,Su,F,W
Sp,Su,F,W
Sp,Su,F,W
Sp.Su.F
F
Sp.Su.F
Sp.Su.F
Sp.Su.F
Sp.Su.F
hotline, public ed
public ed, newspaper, bill stuffers
public ed, newspaper, bill stuffers
word-of-mouth
hotline, newspaper ad
newspaper ad, mailings
newspaper ad
public ed
free bags yr 1 , mailings
(a) "backyard" refers to backyard composting
(b) Sp - spring, Su - summer, F - fall, W - winter; (2/F - 2 collections per fall, etc.)
Y/N: yea/no
n/a: not available for collection
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31
addition, grass clippings and brush which are not dropped off
to be composted or shredded are either composted or mulched
in backyards or collected by landscaper services. Also, half
of the programs allow drop-off by commercial landscapers.
Several communities use more than 1 collection method
but, as seen from Table 3, this does not imply that a greater
percentage of households participate than in those
communities relying on only 1 collection method (e.g.,
compare Davis and East Tawas). However, the collection
method can affect the composting process (e.g., curbside
pickup by vacuum versus drop-off in plastic bags can affect
whether incoming yard wastes need to be processed prior to
windrow formation). Collection service frequency for yard
wastes varies from weekly to seasonally and occurs during 1,
2, 3, or all 4 seasons. Choice of seasons for collection
service is in part determined by the type of yard wastes
composted; e.g., Montgomery County currently only composts
leaves (see Table 5) and therefore collects during the fall
and spring when leaves are available for pickup at curbside.
In addition, some collection equipment (e.g., curbside
vacuum) is not suited for year-round yard waste pickup. In
each of these cases of curbside collection, yard wastes are
collected independently of the normal trash collection.
Various methods (e.g., media ads, education, bill
stuffers, and posted signs) have been used to raise public
awareness and support for participation in these composting
programs. Nevertheless, there is no apparent indication of
whether any particular method influences the rate of
household participation the most, nor whether multiple
methods are more effective than single methods in maximizing
the participation rate (e.g., compare Montgomery County to
Seattle and Wellesley).
E. Table 5: Yard Waste Composting Facilities
Composting operations serving the 8 selected
communities are described in Table 5. They are split between
publicly and privately owned and operated facilities.
Facilities referred to as public are those which are owned
and operated by towns, cities, or counties. (However,
Montgomery County's facility is operated by a private
contractor on public land.) Private facilities are privately
owned companies which perform composting on their land for 1
or more clients which may include other private companies
(such as landscapers or private haulers) , as well as
communities. Ownership affects location of these facilities
~ publicly operated facilities are located within the
community's boundaries; however, this need not be true in the
case of privately operated facilities.
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32
Table 5: Yard Waste Composting Facilities
City or
County
Davis (a)
East Tawas
Montgomery Co.
Omaha
Seattle (d) (e)
Wellesley (f)
Westfield (g)
Woodbury (i)
Notes:
State
CA
Ml
MD
NB
WA
MA-RDF
MA-DPW
NJ-MCI
NJ-WL
MN
Public/
Private
Facility
private
public
public/
private
public
private
public
public
private
private
private
Location of Size of Total Yard Composition of Yard
Compost Compost Waste Waste Stream
Facility Area Composted Composted (% by wt.)
(acres) (tons/yr) [Leaves [Grass [Brush
inside city
at closed landfill
city
at
out
outskirts
landfill
of city
at transfer stat.
at DPW yard
out
out
of city
of city
out of city
(a) a private facility,
Davis Waste
2.5
2.5
47 1
2
6
1.5
1
15
4.5
2
Removal
500
138
5,600
500
3,600
n/a
n/a
1,730
1,400
-116
, is used
100
91
100
20
n/a
62
100
100
0
36
0
9
0
60
n/a
38
0
0
100
64
0
(b)
0
20
n/a
0
0
(b)
(b)
0
Permit
Required
(Y/N)
N
N
N (c)
N
N
N
N
Y(h)
Y(h),
Y (j)
for composting
(b) brush is chipped; at East Tawas, it is used for road fill; at Westfield, it is
sent to Alternate Disposal Systems Inc., a private facility
(c) however, permits are required for surface water discharges from facility's
sedimentations ponds
(d) a private facility, Pacific Topsoils, Inc., is used for composting
(e) it is impossible to provide accurate data on the amount and range of
backyard composting performed
(f) MA-RDF - Wellesley's yard waste composting facility located at its Recycling
and Disposal Facility
MA-DPW - Wellesley's yard waste composting facility located at its DPW yard
(g) NJ-MCI - Middlebush Compost, Inc., a private facility used by Westfield
NJ-WL - Woodhue Ltd., a private facility used by Westfield
(h) state solid waste facility permit
(i) a private facility, Composting Concepts, is used for composting
(j) land use permit
n/a: not available
Y/N: yes/no
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33
There is no clear relationship evident between the size
of the composting facilities and the amount of yard wastes
composted. At least 3 factors may explain this: (1) land
area is in part determined by the technology used (and vice
versa) and efficiency with which land is used; (2) private
facilities may accept yard wastes from many communities to
benefit from the economies of scale — however, Table 5 only
includes yard wastes for communities included in this study;
and (3) the facility's land and equipment (e.g., East Tawas)
may also be used to grind rather than compost brush. For
these reasons, sufficient data are not available to estimate
tons (or cubic yards) of yard wastes composted per acre of
composting area.
The level of composting activity at these facilities
ranges widely, from 116-15,600 tons per year. The majority
of yard debris accepted by these facilities is leaves;
however, several facilities accept significant quantities of
grass.
Of these 10 yard waste composting facilities, only the
New Jersey facilities operate subject to state solid waste
facility permits. The Woodbury facility is subject to a
permit but this relates more to its land use activity as a
commercial-type enterprise. The Montgomery County facility
has a permit but it applies only to surface water discharges
from its sedimentation ponds.
F. Table 6: Yard Waste Composting Facility Operations
The previously discussed definitions for the composting
technologies (see Table 1) have been modified in Table 6 to
fit the technologies used at these facilities. Every
facility is different, therefore, the division of these 10
facilities into 3 technology groups has been performed
somewhat loosely. For purposes of this report, minimal-level
technology includes windrow turning frequencies of at most 2
times per year; low-level technology includes windrow turning
frequencies of at least once every 2 months; and
intermediate-level technology requires a windrow turning
machine and turning at least once per month.
Most of these facilities either grind or shred the
incoming yard wastes or shred during the windrow turning
process. This serves to accelerate the composting process
and reduce the volume of yard wastes. Six of the 10
facilities screen their compost to improve product quality.
As seen from Tables 6 and 8 (revenues earned from marketing
compost), use of these processing steps depends, in general,
on the selling price or value of the finished compost.
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34
City or
County
Table 6: Yard Waste Composting Facility Operations
State Type of Turning Grind/ Monitor/ Monitor/ Facility Water
Compost Frequency Shred/ Testing Testing Control Added
Tech Screen During Frequency (a)
Used Material Composting
Process
Davis
East Tawas
Montgomery Co.
CA
Ml
MD
Low
Low
Intermed
1/week
6/year
1 /month
grind
none
shred
none
temp
temp
n/a
1/1-2 mos
1/month
none
none
RO.W
N
N
N
Omaha
Seattle
Wellesley (b)
Westfield (c)
Woodbury
Notes:
screen compost 1/year
NB Minimal 2/year grind
temp 1/2weeks none
compost 1/year
WA Minimal 1/year grind temp 1/month none
shred compost 1/3months
screen
MA-RDF Minimal 1/year screen temp 1/2weeks none
compost 1/1-2years
MA-DPW Low 1/month screen temp 1/2weeks none
compost 1/1-2years
NJ-MCI Intermed >1/week shred temp 1/day none
screen moisture 1/day
oxygen 1/week
compost 1/month
NJ-WL Intermed as needed shred temp
(d) screen moisture at start
oxygen 1/10days
compost varies
MN
Low 1/month none
temp 1/2month none
compost 1/year
N
N
N
1/ 2days none Y
(a) RO - collects runoff, W - wind fence to collect pieces of plastic bags
(b) MA-RDF - Wellesley's yard waste composting facility located at its Recycling
and Disposal Facility
MA-DPW - Wellesley's yard waste composting facility located at its DPW yard
(c) NJ-MCI - Middlebush Compost, Inc., a private faicility used by Westfield
NJ-WL - Woodhue Ltd., a private facility used by Westfield
(d) turning occurs as needed, based on temperature inside the windrow
n/a: not applicable
Y/N: yes/no
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35
Only Montgomery County indicated the presence of
environmental controls at their facility — (1) sedimentation
ponds for collecting runoff, installed when the facility
previously composted municipal sewage sludge; and (2) a wind
fence to collect pieces of plastic. Several facilities add
water when windrows are initially formed or turned, generally
independent of technology used and frequency of windrow
turning. No other additives were mentioned. Most of the
facilities monitor windrow temperature as an indicator of the
composting process and test the quality of the finished
compost. Monitoring is generally more extensive and frequent
for the private composting facilities and, as such, is
related to the value of the end product (see Table 8 for
revenues per ton of compost sold).
G. Table 7: Yard Waste Composting Results
As seen in Table 7, volume reduction of yard wastes
generally depends on composting time and the type of
technology used (refer back to Table 6) . To achieve a
specific percent reduction of yard wastes, composting time
can be decreased if the technology is "upgraded" to a more
advanced level (e.g., through more frequent turnings). The
time required to produce finished compost is influenced by
the frequency of turning, as well as climate.
Markets for the finished compost include local
residents, local governments, nurseries, and landscapers.
There is sometimes a time lag between when the finished
compost is ready to be marketed and when the market will buy
the product. This is evident in the case of Montgomery
County which collects leaves in the fall and spring and can
produce finished compost by the following fall, but may have
to store its finished compost for 6 months on-site and wait
until the next spring to sell it.
Reject materials, e.g., plastic bag debris, tennis
balls, and rocks, which are not composted, is separated
manually (e.g., during debagging) or mechanically (e.g.,
during screening) and sent to a landfill for disposal. This
material constitutes between negligible levels and 25 percent
of the incoming yard waste stream at these facilities and is
highly dependent on the methods used for yard waste source
separation, collection, and processing, and to some extent on
street sweeping in the case of curbside pickup.
H. Table 8: Costs and Revenues of Yard Waste
Composting
Costs and revenues reported by these yard waste
composting programs are provided in Table 8. Yard waste
collection and transport costs for these communities range
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36
Table 7: Yard Waste Composting Results
City or
County
Davis
East Tawas
Montgomery Co.
Omaha
Seattle
Wellesley (f)
Westfield (g)
Woodburv
State
CA
Ml
MD
NB
WA
MA-RDF
MA-DPW
NJ-MCI
NJ-WL
MN
Composting
Time
(months)
3 - 4 (b)
24 - 3S
6 - 12
18-24
6 - 8
24
12
3 - 4
5
12
Yard Waste
Volume
Reduction
(%)
50 - 60
65
85
50 - 60
80
60-65
60-65
80
50 - 70
70
Tons of
Finished
Product
(tons/yr)
250
70 - 80
3500
350
(d)
1800
800
(h)
(h)
(i)
Compost
Uses &
Markets
(a)
V
R
C
L,N
C
L,R,C
R,N
C
L,N,R
F
N
Rejects
(as % of
Incoming
Volume of
'ard Wastes)
2 - 5 (c)
1
5 - 10
n/a
1 (e)
neg
5
1
12-25
1
Year
1987
1987
1987
1988
1988
1987
1987
1988
1988
1987
Notes:
(a) C - city/county, F - farm, L - landscapers, N - nurseries, R - residents
(b) however, the composting process may not be completed after 3-4 months
(c) by weight
(d) Pacific Topsoils, Inc. composts yard wastes for Seattle and other cities;
hence, it is not possible to separate out data for Seattle alone
(e) reject material gets used on-site or sold
(f) MA-RDF - Wellesley's yard waste composting facility located at its Recycling
and Disposal Facility
MA-DPW - Wellesley's yard waste composting facility located at its DPW yard
(g) NJ-MCI - Middlebush Compost, Inc., a private facility used by Westfield
NJ-WL - Woodhue Ltd., a private facility used by Westfield
(h) Middlebush Compost, Inc. and Woodhue Ltd. compost leaves and grass,
respectively, from Westfield, and primarily leaves from other communities and
private clients. It is not possible to separate out data for Westfield alone
(i) Composting Concepts composts yard wastes from Woodbury and other communities;
hence, it is not possible to separate out data for Woodbury alone
neg: negligible
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37
Table 8: Costs and Revenues of Yard Waste Composting
City or
County
Davis
East Taws
Mont. Co.
Omaha
Seattle (e
Wellesley
Westfield
Westfield
Woodbury
Notes:
State Collection Processing Total Buyers& Compost Garbage Local
&Transport Cost for Compost Users of Revenues Collection Landfill
Cost for Yard Wastes Cost Compost by Market STransport Tip Fee
Yard Wastes ($/ton) (excl. (a) ($/ton) Cost (S/ton)
(S/ton) revenue) (b) ($/ton)
($/ton)
CA n/a n/a n/a R $0.00 n/a S8.00
is (c) Ml $10.00 <$10.00 <$20.00 C $0.00 n/a $5.25
(d) MD $83.33 $18.46 $101.79 L,N $19.20 $54.00 $46.00
NB $40.16 $3.60 $43.76 C AC $30.30 $6.40
) WA $12.00 $22.50 $34.50 L,R,C $7.50- $71.50 $31.50
$12.507
cu yd
(f) MA $0.00 $11.11 $11.11 N $0.50 $0.00 $52.00
R $0.00
C AC
(g)(h)NJ-MCI $16.79/c y $7.50/cu yd$24.29/ c y L,N,R $25.00 n/a $137.00
(g) NJ-WL (i) $10/cu yd n/a F AC n/a $137.00
MN $43.00 $15.00 $58.00 N AC $65.00 $30.00
(a) C - city/county, F - farm, L - landscapers, N - nursery, R - residents
(b) AC - avoided cost of topsoil for landfill cover, park services projects, private use,
use of land, etc. For example, avoided costs for landfill cover and soil amendment
for Omaha are $8-$10/ton plus $1-$5/ton for transport of topsoil; avoided cost
by $15/cu yd for Weilesley as substitute for loam; avoided cost by $35-$65/acre
for farm use as fertilizer supplement at Woodhue Ltd.; avoided cost of land for
Woodbury by exchanging compost for use of nursery's land
(c) costs for equipment shared with DPW are not included in composting costs
(d) processing costs do not include costs for land, amortized capital costs, nor
disposal costs for reject material
(e) collection cost not included in 1988 estimate, $56/ton in 1989; conversion factor
for Pacific Topsoils, Inc. ranges between 1/2-3/4 tons/cu yd for finished compost
(f) yard wastes are dropped off at composting facilities; therefore, zoro municipal
costs for collection and transport; costs do not include landfill disposal of rejects,
nor costs of land; $52/ton tip fee includes transport cost to landfill
Year
1987
1987
1987
1988
1988
1987.'
1988
1988
1988
1987
-------
Notes:
38
Table 8 (cont.): Costs and Revenues of Yard Waste Composting
(g) NJ-MCI - Middlebush Compost, Inc., a private facility used by Westfield
NJ-WL - Woodhue Ltd., a private facility used by Westfield
conversion factor used by New Jersey is 700 Ibs/cu yd, or 1 ton/3.3 cu yds
$137/ton is tip fee at the transfer station
(h) collection cost includes rented equipment, labor, fuel; does not include shared equipment
(i) collection cost of grass for Westfield is $0 with resident drop-off; cost for transport
to WL was not estimated by Westfield
n/a: not available
cu yd: cubic yard
c y: cubic yard
-------
39
from $0 per ton (for drop-off) to over $80 per ton, while
processing costs are generally much lower, spanning a
narrower range, approximately $4-$23 per ton. Footnotes to
Table 8 indicate what costs are and are not included in these
cost estimates. Although collection, transport, and
processing costs to a community are $0 per ton for backyard
composting, costs may still be incurred if it provides
technical assistance and/or materials to residents.
As mentioned above, users of compost material include
local residents (at a small fee or no charge), local
governments, nurseries, and landscapers. The material is
used primarily as a soil amendment or landfill cover by these
communities. In all cases, the finished compost is
distributed to users in bulk, rather than in bags.
Generally, the product is picked up by the buyer, although,
in some cases, delivery is available as well.
Revenues from selling the finished compost range from
$0 (e.g., it is given free to residents) to $25 per ton. In
addition, when revenues are not received, there may be
avoided costs, as in the cases of using compost: (1) as a
landfill cover material and soil amendment for county parks
(at Omaha, $8-$10 per ton plus $l-$5 per ton transport costs
saved for topsoil); (2) as a soil amendment (at Wellesley,
$15 per cubic yard savings) ; (3) for private use as a
supplement to fertilizer (at Woodhue Ltd., $35-$65 per acre
savings); or (4) in exchange for use of another facility's
land (at Woodbury, with a nursery's land). Total revenues
earned by the communities (i.e., for the publicly operated
facilities) can be subtracted from the total costs of
composting (collection plus transport plus processing) to
give the net total costs of composting (not shown in Table
8) . In New Jersey, there is also a tonnage grant for
recycling — the state will pay communities $l-$2 per ton of
MSW diverted from landfill as a recycling incentive as well
as a tracking mechanism for the level of recycling activity.
Costs and revenues can be reported in total amounts or
on a per ton basis. However, when revenues are reported as
the price received per ton of finished compost sold, and
costs are reported as expenditures per ton of yard wastes
received, a conversion is needed so that these individual per
ton estimates are compatible to estimate the net per ton cost
of composting. The conversion is as follows: multiply the
ratio of tons of finished compost sold to tons of yard wastes
received, by the revenue earned per ton of finished compost.
This revenue figure can now be subtracted from the cost of
composting, per ton of yard wastes received, to estimate the
net costs of composting, per ton of yard wastes received.
Similar steps would be needed if the cost and revenue figures
were based on cubic yards rather than tons.
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40
Landfill tip fees have been steadily and substantially
increasing nationally (Petit, 1988). These costs are
generally expected to continue to increase in the future. In
some areas, these costs have recently skyrocketed. These
high landfill disposal fees, as seen by Westfield's $137 per
ton fee at the transfer station, offer strong economic (as
well as the environmental and landfill capacity) reasons for
yard waste composting.
By integrating composting into their overall MSW
management strategy, communities are able to divert yard
wastes from landfills (or incinerators) and derive cost
comparisons for strategies with, and without, composting.
The total cost of composting is derived by adding the costs
for collecting, transporting, and processing yard wastes
(similarly, adding their costs per ton multiplied by the
amount of yard wastes diverted) . The total net cost of
composting is determined by subtracting revenue (or avoided
cost from use of compost as a substitute product) to the
community for the sale of compost from the total cost of
composting. The total MSW management (with composting) cost
is calculated by adding the total net cost of composting and
the cost of managing the remaining MSW, and then subtracting
the avoided landfill disposal cost due to composting. This
total MSW management cost estimate should then be compared to
the MSW management without composting scenario (e.g., use MSW
tonnage and per ton collection, transport, and landfill
disposal costs or total costs for each of these activities)
to determine if yard waste composting is a cost-effective MSW
management alternative.
Many communities are becoming increasingly aware that
yard waste composting will save them landfill disposal costs
and precious landfill space. As stated above, cost savings
by diverting yard wastes from landfills, i.e., avoided tip
fees, can be subtracted from the total net cost of composting
to estimate the real, or "true" cost of composting. Of
course, this assumes that the cost of landfilling (and
composting) reflects its true cost. To avoid double-counting
costs, the true cost of composting should not be compared
again to the cost of landfilling since both cost measures
include estimates of landfill disposal costs, whether avoided
or to be paid.
Direct cost comparisons between these 8 community
composting programs may not be appropriate because their cost
figures may be based on different accounting, estimation,
and/or financial procedures (GPI, 1988). For example: (1)
East Tawas' cost estimates only reflect costs solely
applicable to composting, i.e., costs for equipment shared
with their DPW were not estimated; (2) Montgomery County's
estimate for its processing cost does not include the
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41
opportunity cost for land nor amortized capital costs, the
latter being paid in single lump sums; (3) Montgomery
County's and Wellesley's processing costs do not include
costs for landfill disposal of reject material; (4) Wellesley
does not include the cost of land; and (5) Westfield does not
include the cost of shared equipment, only rented equipment
(as well as labor and fuel), in its processing cost estimate.
Furthermore, cost per ton estimates for composting can be
highly variable over time, depending on, among other things,
annual fluctuations in the amount of yard wastes generated.
I. Table 9: Contact Information
Names, affiliations, and phone numbers of the
representatives interviewed from each composting program are
listed in Table 9.
X.
Conclusions
The yard waste composting programs examined in this
study represent some of the options available for designing
such programs. The components of these programs are
apparently site-specific, affected by local _factors,
community composting experience, etc. The summary highlights
of the programs studied and assessed include the following
findings:
o the percentage of yard waste diverted from
landfilling is highly dependent on community and
household participation levels, composition of the
yard waste stream, and types of yard wastes
composted (or, in the case of brush, shredded);
o volume reductions of the yard wastes composted
range between 50 and 85 percent;
o the number of process steps, including technology
used, shredding, screening, monitoring, testing,
etc. is related to the available land, labor, and
capital and the desired quality and value of the
end product;
o composting costs (excluding revenues earned) range
from $11-$102 per ton, and avoided landfill
disposal fees range between $5-$137 per ton; and
o in several cases, revenues were generated through
sale of the finished compost (up to $25 per ton)—
in other cases, costs were avoided by saving on
costs for landfill cover, soil amendment, private
use, or land.
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Table 9: Contact Information
City or County State Contact Name Agency or Company
Phone Number
Davis
East Tawas
Montgomery Co.
Omaha
Seattle
Wellesley
Westfield
CA Ken Shepard
Woodbury
Ml
Jacob Montgomery
MO Dave Wagaman
Bob Goldberg
NE Dan Slattery
WA Nora Smith
Leo Carlson
Dorran McBride
MA M.R. -Pat" Berdan
NJ Edward Gottko
Pat Kennedy
Joseph Hayes
G. 'Nick' Nicholson
MN John Madole
Richard E-isinger
Davis Waste Removal Co. (916)756-4646
City of East Tawas (517)362-6161
Montgomery County Gov't (301)217-2380
Montgomery County Gov't (301)217-2380
City of Omaha
(402)734-6060
Seattle Solid Waste Utility (206)684-7638
Pacific Topsoils, Inc. (206)486-3201
Pacific Topsoils, Inc. (206)486-3201
DPW Director
(617)235-7600
Town Engineer Westfield DPW(201)789-4100
Middlebush Compost Inc. (201 )560-0222
WoodhueLtd. (609)723-6211
WoodhueLtd. (609)723-6211
John C. Madole Assoc.
Composting Concepts
(612)489-5779
(612)436-5994
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43
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Mattheis, A. 1987. "New Jersey Lays Down the Law". Waste Age.
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Appendix A: Sample Conversion Factors
Conversions Used by the Composting Facilities
Montgomery County, Maryland:
incoming leaves (after vacuuming)
Omaha, Nebraska:
incoming yard wastes
Seattle, Washington—Pacific Topsoils, Inc.:
gross material at entry
after composting for about 2 months and
shredding
finished compost sold as topsoil
400 Ibs/cu yd
600 Ibs/cu yd
400 Ibs/cu yd
1,000
1,500
Wellesley, Massachusetts:
uncompacted fresh leaves
after composting for one year
finished compost
400-450
1,272
1,500
Westfield, New Jersey—Middlebush Compost Inc.:
loose fresh material
stockpiled compost material
Westfield, New Jersey—Woodhue Ltd.:
incoming yard wastes
Woodbury, Minnesota—Composting Concepts:
250
800
Ibs/cu yd
Ibs/cu yd
Ibs/cu yd
Ibs/cu yd
Ibs/cu yd
Ibs/cu yd
Ibs/cu yd
600 Ibs/cu yd
compacted dry leaves
compacted pure new grass
partially compacted gross material
at entry
after 2 months composting and
shredding
density of material sold
320
1,500
Ibs/cu yd
Ibs/cu yd
400 Ibs/cu yd
1,000
1,500
Ibs/cu yd
Ibs/cu yd
A-l
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Conversions Found in the Literature
City of Seattle (1988):
compacted yard debris
grass
leaves
prunings
yard debris
Fliesler (1987):
leaves, assuming average rate of
compaction ,
McCown (1988):
loose leaves
vacuumed leaves
compacted leaves
bagged grass (30 gallon bag at 80%
capacity =50 Ibs)
Mielke and Walters (1988):
compacted leaves
Public Technology, Inc. (1988):
uncompacted leaves
Strom and Finstein (1986):
leaves in open truck
vacuumed, leaves
compacted- leaves
leaves—rough average
600 Ibs/cu yd
800 Ibs/cu yd
420 Ibs/cu yd
210 Ibs/cu yd
390 Ibs/cu yd
500 Ibs/cu yd
250 Ibs/cu yd
350 Ibs/cu yd
450 Ibs/cu yd
421 Ibs/cu yd
400 Ibs/cu yd
500 Ibs/cu yd
250 Ibs/cu yd
350 Ibs/cu yd
450 Ibs/cu yd
400 Ibs/cu yd
A-2
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