United States
Environmental Protection
Agency
Solid Waste
and Emergency Response
(5306W)
EPA530-R-99-016
July 1999
www.epa.gov
Organic Materials
Management Strategies
@ Printed on paper that contains at least 30 percent postconsumer fiber.
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Organic Materials Management Strategies
CONTENTS
EXECUTIVE SUMMARY 1
1. ORGANIC MATERIALS IN THE NATIONAL WASTE STREAM 5
1.1 Applicable Portion of the National Organic Waste Stream 5
1.2 Regional Variation in Yard Trimmings Composition 6
2. ESTIMATING AVOIDED DISPOSAL COSTS ATTRIBUTABLE TO DIVERSION OF
ORGANIC MATERIALS 7
2.1 Avoided Disposal Costs and Tipping Fees 7
2.2 State Tipping Fees and RCRA Regulations 8
2.3 Avoided Mixed Waste Collection Costs 10
3. ORGANIC MATERIALS MANAGEMENT STRATEGIES 11
3.1 Grasscycling 13
3.1.1 Strategy Summary 13
3.1.2 Strategy Description 13
3.1.3 Technical Problems 14
3.1.4 Applicable Portion of the National Waste Stream Diverted 14
3.1.5 Costs Per Ton Diverted 14
3.2 Backyard Composting 15
3.2.1 Strategy Summary 15
3.2.2 Strategy Description 15
3.2.3 Technical Problems 17
3.2.4 Applicable Portion of the National Waste Stream Diverted 17
3.2.5 Costs Per Ton Diverted 18
3.3 Yard Trimminss ConiDostins? 19
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3.3.1 Strategy Summary 19
3.3.2 Strategy Description 20
3.3.2.1 Collection Programs 20
3.3.2.2 Composting Facilities 20
3.3.3 Technical Problems 21
3.3.3.1 Collection Systems 21
3.3.3.2 Facilities 21
3.3.4 Applicable Portion of the National Waste Stream Diverted 21
3.3.5 Costs Per Ton Diverted 21
3.4 Onsite Institutional Composting 23
3.4.1 Strategy Summary 23
3.4.2 Strategy Description 23
3.4.2.1 Correctional Facilities 24
3.4.2.2 Universities 24
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Organic Materials Management Strategies
3.4.4 Applicable Portion of the National Waste Stream Diverted 26
3.4.5 Costs Per Ton Diverted 26
3.5 Commercial ComDostins? 27
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3.5.1 Strategy Summary 27
3.5.2 Strategy Description 28
3.5.3 Technical Problems 28
3.5.4 Applicable Portion of the National Waste Stream Diverted 29
3.5.5 Costs Per Ton Diverted 30
3.6 Mixed \Vaste Composting 32
3.6.1 Strategy Summary 32
3.6.2 Strategy Description 32
3.6.3 Technical Problems 33
3.6.4 Applicable Portion of the National Waste Stream Diverted 33
3.6.5 Costs Per Ton Diverted 33
3.7 Residential Source-Separated Composting 35
3.7.1 Strategy Summary 35
3.7.2 Strategy Description 36
3.7.3 Technical Problems 37
3.7.4 Applicable Portion of the National Waste Stream Diverted 38
3.7.5 Costs Per Ton Diverted 39
4. COMPOST MARKETS AND PRODUCT VALUE 40
4.1 Review of Benefits Associated With Compost End-Uses 40
4.1.1 Direct Benefits to Soil 40
4.1.2 Indirect Environmental and Economic Benefits 40
4.2 Overview of Compost Markets, Applications, and Constraints 41
4.3 Compost Product Quality 45
4.4 Fertilizer Substitution 47
4.5 Potential Market Value of Compost 48
5. SUMMARY AND CONCLUSIONS 50
5.1 Midrange Savings of Organic Materials Management Strategies 51
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Organic Materials Management Strategies
TABLES AND FIGURES
Figure ES-1 Savings Per Ton of Organic Diversion (Compost Strategies Savings Curve) 2
Table 1-1 Applicable Portion of the National Waste Stream Targeted by the Composting Strategies
Described in This Report 6
Table 2-1 Average Landfill Tipping Fees by State 9
Table 2-2 Avoided Mixed Waste Collection Costs Associated With Leaf and Yard Trimmings
Composting Programs 10
Table 3-1 National Summary of Strategy Impacts 12
Table 3-2 Grasscycling Program Costs 15
Table 3-3 Backyard Composting Program Costs 19
Table 3-4 Select Windrow Compost Facility Throughput and Costs 23
Table 3-5 Potential Onsite Institutional Composting Diversion Rates 26
Table 3-6 Onsite Institutional Composting Program Costs 27
Table 3-7 Applicable Portion of the Waste Stream Available for Commercial Composting 29
Table 3-8 Collection, Processing, and Combined Costs Per Ton 31
Table 3-9 Mixed Waste Composting Facility Costs 35
Table 3-10 Applicable Portion of the Waste Stream Available for Residential Source-Separated Composting 38
Table 4-1 Compost Markets, Applications, and Potential Constraints 42
Table 4-2 Comparison of Compost Beneficial Use Parameters 46
Table 4-3 Reported Revenues for Various Compost Program End-Products 49
Table 5-1 National Summary of Strategy Impacts 50
Table 5-2 Midrange Savings Per Ton Diverted for Compost Strategies 52
Figure 5-1 Savings Per Ton of Organic Diversion (Compost Strategies Savings Curve) 52
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Organic Materials Management Strategies
EXECUTIVE SUMMARY
Organic materials make up the bulk of America's discarded municipal solid waste (MSW). In
1996, organic materials accounted for 141 million tons (67 percent) of the waste stream. Some
organic materials, such as newspaper, office paper, and corrugated, have a high recovery rate.
Other organic materials (e.g., yard trimmings, food scraps, and certain grades of paper),
however, still tend to be landfilled and represent an area with high growth potential for recovery
(75 million tons). Depending on the type of waste and method of composting selected, average
national savings over conventional disposal vary from $9 to $37 per ton for 62 million tons of
the MSW stream.
This report describes seven composting strategies for organic materials in the U.S. MSW stream
and presents an analysis of the benefits and costs of each strategy, the potential for diverting
organic materials from landfills or waste-to-energy facilities, and the potential markets for
diverted organic materials. This report is organized into five sections: (1) an overview of organic
materials in the national waste stream, (2) estimates of avoided collection and disposal costs
attributed to diversion of organic materials, (3) descriptions of the organic materials management
strategies, (4) a review of compost markets and end-uses, and (5) a summary and comparison of
the net costs of each composting strategy.
This report focuses on the following seven composting strategies:
• Grasscycling: residential, commercial, and institutional establishments leave cut
grass on their lawns.
• Backyard composting: homeowners compost food scraps and yard trimmings on
their property.
• Yard trimmings composting: leaves, grass, and brush are collected and composted
at central facilities.
• Onsite institutional composting: institutions (e.g., universities, schools, hospitals,
etc.) process food scraps, paper, and yard trimmings at onsite composting facilities.
• Commercial composting: commercial organic materials generators (e.g.,
supermarkets, restaurants, schools, etc.) collect and separate organic materials for
collection and composting.
• Mixed waste composting: mixed waste composting facilities separate MSW into
component streams for composting, recycling, and refuse disposal.
• Residential source-separated composting: homeowners separate specific organic
materials and set them out for collection and processing.
For each of these seven strategies, the following two major categories of information are
presented:
• A description of the key aspects of each strategy, based on current applications,
including a discussion of numerous individual programs.
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Organic Materials Management Strategies
• A comparative analysis of the benefits and costs of each strategy as well as an
estimate of the applicable portion of the organic waste stream each strategy targets.
The comparative results in this report are summarized in the compost strategies savings curve
that follows. The curve indicates that of the organic waste stream available for composting using
existing strategies and technologies (approximately 75 million tons), a total of 83 percent (62
million tons) could be composted at a net benefit to society (i.e., savings over traditional disposal
methods) through a combination of grasscycling, backyard composting, onsite institutional
composting, yard trimmings composting, and commercial composting. The term 'available (or
applicable) organic waste stream' indicates that newspaper, office paper, and corrugated have
already been removed for recycling. Grasscycling, onsite institutional composting, and backyard
composting programs could target 50 percent (37 million tons) of the applicable portion of the
organic waste stream at the greatest net benefit to society. Alternatively, yard trimmings
composting programs could capture some of the organic materials targeted by these programs.
Commercial composting could capture another 33 percent (24.6 million tons) of the applicable
organic waste stream at a net benefit. Composting the remaining 17 percent (13 million tons) of
the applicable organic waste stream could be accomplished through more costly mixed waste
composting or source-separated composting once this strategy becomes better established in the
United States.
Figure ES-1
Savings a Per Ton of Organic Diversion
(Compost Strategies Savings Curve)
.- O
> Q
OT ±
$35 •
$30 '
$25 •
$20
$ 1 5 '
$0
On-Site Institutional Compostinc
ackyard Composting
'Commercial Compostinc
40 50 60
Millions of Tons
Notes:
a These savings are from the viewpoint of local government and assume that any additional labor required from citizens is donated
at no cost to society.
bTo be conservative, we assume no savings in collection costs. The tonnage in these composting programs is not reduced
significantly enough to affect the cost of collection.
0 Based on the applicable portion of the organic waste stream available for composting using existing strategies and
technologies.
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Perhaps the most striking general result revealed by the savings curve is the cost differential
between onsite compost strategies (e.g., grasscycling, backyard composting, and onsite
institutional composting) on the one hand and more conventional collection-based compost
technologies (e.g., yard trimmings composting and commercial composting) on the other. While
this result promises a real impact on local governments' budgets, it reflects an assumption that
the labor required by citizens in grasscycling or backyard composting is donated at no cost to
society.
More specifically, this report supports the following conclusions:
• Approximately 36 percent (75 million tons) of the U.S. MSW stream is available for
composting using existing strategies and technologies. In this report we have assumed
that the 75 million tons of available organic materials do not include newspaper,
office paper, and corrugated, because these materials are currently being recovered
for recycling at high rates.
• Depending on the type of waste and method of composting selected, average national
savings over conventional disposal vary from $9 to $37 per ton.
• Organic source reduction programs, including grasscycling, onsite institutional
composting, and backyard composting, are quite cost-effective when compared to
other composting alternatives. This cost-effectiveness results from low program costs,
which are more than offset by avoided disposal costs, under the assumption that the
labor required by citizens is donated at no cost to society. In combination, these
strategies could target about 37 million tons of the available organic waste stream.
• Approximately 62 million tons of the available organic waste stream could be
targeted by a combination of grasscycling, backyard composting, yard trimmings
composting, onsite institutional composting, and commercial composting programs at
a net benefit (savings over traditional disposal methods).
• Yard trimmings composting (a form of residential source-separation) is the most well
established and widespread of the composting strategies in the United States. This
strategy could target about 28 million tons of leaves, grass, and brush.
• Although mixed waste composting facilities appear somewhat cost-effective, these
facilities have experienced substantial setbacks in the past few years. Public
opposition and technical difficulties have been troublesome for mixed waste compost
facilities in the United States. As a result, the United States saw a 25 percent decline
in the number of operating mixed waste compost facilities between 1992 and 1995.
• Residential source-separated compost programs, which include food scraps, soiled
paper, and yard trimmings, are well established and successful in Europe. This
composting strategy, however, is still in its infancy in the United States. Nevertheless,
European experience suggests that residential source-separated composting programs
might offer a viable alternative for capturing a significant percentage of the organic
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materials available for composting that are not targeted by established strategies or
technologies.
• The potential market for finished compost is much larger than the potential supply.
This situation is supported by the fact that virtually all municipalities and/or
companies that currently produce compost products have established markets for
those products. In addition, they are often unable to meet the demand for their
compost products. If all applicable materials addressed in this report were captured
for composting, approximately 48 million cubic yards (37.4 million tons) of finished
compost would be created each year. End-uses for compost in agriculture,
silviculture, residential retail, nursery sod production, and landscaping might have a
market potential of more than 1 billion cubic yards of finished compost.
The conclusion of this report is that composting is feasible on almost every size scale, and it
works. The more material that is composted, the lower the cost per ton to operate whatever
composting strategy is used. The most important part of a successful composting operation,
however, is choosing a strategy or combination of strategies that works for particular
circumstances.
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Organic Materials Management Strategies
1. ORGANIC MATERIALS IN THE NATIONAL WASTE STREAM
Organic materials make up the bulk of America's discarded municipal solid waste (MSW). In
1995, organic materials accounted for 141 million tons (67 percent) of the waste stream, as
reported in the U.S. Environmental Protection Agency (EPA) study Characterization of
Municipal Solid Waste in the United States: 1997 Update (the 7997 Update)1 Some organic
materials, such as newspaper, office paper, and corrugated, have a high recovery rate. Other
organic materials (e.g., yard trimmings, food scraps, and certain grades of paper), however, still
tend to be landfilled and represent an area with high growth potential for recovery. In recent
years, numerous programs have been set up to divert organic materials from the waste stream
and create beneficial uses for them. These programs include the following:
• Grasscycling, or leaving cut grass on lawns.
• Backyard composting of food scraps and yard trimmings.
• Yard trimmings composting at central facilities.
• Onsite institutional composting of organic materials.
• Commercial composting operations that target materials generated by commercial
and industrial establishments.
• Mixed waste composting at centralized processing facilities that accept mixed refuse
and separate this material into composting, recycling, and disposal streams.
• Residential source-separated composting systems that target specific organic
materials separated by the generator, set out for collection, and processed at a central
dedicated compost facility.
This report provides a detailed analysis of each of the strategies listed above, based on programs
implemented by public and private organizations across the nation. Larger programs could see
even greater savings since many of the programs in this study are relatively small. For each
strategy, the following two major types of information are presented:
• A description of the key aspects of each strategy, based on current applications and
engineering estimates, including a discussion of numerous individual programs.
• A comparative analysis of the benefits and costs of each strategy as well as an
estimate of the applicable portion of the national organic waste stream each strategy
could potentially divert.
1.1 Applicable Portion of the National Organic Waste Stream
Although 67 percent of the national waste stream is organic in nature, a significant portion of it
(e.g., newspaper, office paper, and corrugated) is currently being recovered for recycling and is,
thus, unavailable for composting. In this report, only the organic materials currently being
1 EPA. 1998. Characterization of Municipal Solid Waste in the United States: 1997 Update. EPA530-R-98-007. Washington, DC.
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managed by the composting strategies described, as well as the amount of compostable material
these strategies potentially could handle, are evaluated. Table 1-1 shows the types and total
quantities of organic materials in the national waste stream addressed by the strategies described
in this report. The information presented is based on the 7997 Update. The table suggests that 36
percent (approximately 75 million tons) of the U.S. waste stream—28 million tons of yard
trimmings, 22 million tons of food scraps, and 25 million tons of soiled or unrecyclable paper—
is available for composting. Please note that the 7997 Update and this report focus only on the
portion of yard trimmings that are not currently being diverted by source reduction programs
(e.g., grasscycling and backyard composting programs).
Table 1-1
Applicable Portion of the National Waste Stream Targeted by
the Composting Strategies Described in This Report
Organic Materials Targeted by
Existing Strategies
Yard trimmings
Food scraps
Folding cartons
Soiled corrugated boxes a
Other nonpackaging paper
Tissue paper and towels
Bags and sacks
Other paper packaging
Paper plates and cups
Milk cartons
Other paperboard packaging
Wrapping papers
ORGANIC MATERIALS AVAILABLE FOR COMPOSTING
TOTAL MSW
PERCENT TOTAL MSW
MSW Reported in the
1997 Update
(Thousands of Tons)
28,000
21,900
5,390
7,300
4,120
2,980
1,980
1,350
950
460
230
50
74,710
209,660
36 percent
Notes:
a According to the Composting Task Force Report by the Grocery Committee on Solid Waste of the Food
Marketing Institute (1991), 6.6 million tons per year of food scraps plus unrecyclable cardboard (soiled, wet, or
waxed) from food retailers are generated at a 3:1 ratio.
1.2 Regional Variation in Yard Trimmings Composition
Yard trimmings make up approximately 13 percent (28 million tons) of the national waste
stream. This number can vary widely, however, from region to region—and within regions—due
to differences in rainfall, temperature, type of natural vegetation, and length of the growing
season. In the southeast region, for example, Fairfax, Virginia, found yard trimmings to be 25
percent of its MSW. Orange County, North Carolina, however, had a yard trimmings average of
only 5 percent. This example illustrates that locations within the same region with similar factors
(e.g., rainfall and temperature) can still vary widely in their yard trimmings percentages.
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Organic Materials Management Strategies
2. ESTIMATING AVOIDED DISPOSAL COSTS ATTRIBUTABLE TO
DIVERSION OF ORGANIC MATERIALS
The management of organic materials involves several different costs and benefits. This section
focuses on one benefit in particular: the reduction in garbage collection and disposal costs, or
'avoided costs.' These avoided costs result from the diversion of organic materials from the
waste stream through composting or other waste reduction programs. The costs for several
leading diversion programs are addressed in Section 3, while benefits due to compost sale and
use are discussed in Section 4.
This section contains the following three subsections:
• The meaning of avoided disposal costs and their relationship to landfill tipping fees
• Data on average tipping fees by state
• Avoided garbage collection costs due to organic materials diversion
2.1 Avoided Disposal Costs and Tipping Fees
Avoided disposal costs include the amount saved on tipping fees by diverting waste to another
solid waste management strategy. While alternative methods for managing MSW are on the rise,
most of the nation disposes of its waste at landfills or waste-to-energy facilities. For the purposes
of this report, avoided disposal costs are based on reported landfill tipping fees and the costs of
Resource Conservation and Recovery Act (RCRA) compliance. In simple terms, a tipping fee is
the price paid by a community or solid waste company to use a waste disposal facility. Under the
textbook economic assumptions of perfect competition, perfect information, and no barriers to
entry (i.e., no obstacles to opening new landfills), landfill prices would be equal to avoided costs.
Needless to say, such idealized conditions do not typically occur. In reality, landfilling often
involves imperfect information, a lack of local competition, and substantial barriers to entry.
Landfill tipping fees are rarely based on any explicit calculation of the fixed and variable costs of
building, operating, and closing a landfill.2 How these fees are determined might not be simple or
consistent from one location to another. MSW disposal facilities incur substantial fixed costs
such as siting and permitting, design, land acquisition, construction, and monitoring. Landfills
also will require eventual closure and long-term postclosure care. These fixed costs do not
necessarily depend directly on the tonnage of waste received.
Care must be used when estimating cost avoidance based on the national averages for tipping
fees because local conditions will more than likely be different. If a low cost disposal area uses
these averages, then the cost avoidance estimations will be overstated. Conversely, a high
disposal cost area will underestimate the savings potential.
No matter what the tipping fee is, however, there is a resulting avoided disposal cost to be gained
by diverting organic materials through other management methods. In this report, a measure
2 Although this analysis does not attempt to model costs, such as fixed costs and closure and postclosure care, these are important variables to
consider. Full cost accounting is a useful tool decision-makers can use to evaluate these costs.
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Organic Materials Management Strategies
based in part on reported tipping fees and in part on costs of RCRA compliance is used as the
best available proxy for avoided landfill costs (see next section).
2.2 State Tipping Fees and RCRA Regulations
Tipping fees vary widely across the country. One of the few comprehensive sources for this
information is BioCycle magazine, which annually reports on state average landfill tipping fees.
Figures for 1997 are shown in column three of Table 2-1 and range from $8 per ton in Illinois to
$80 per ton in Alaska. The population-weighted national average is $35 per ton.
Many of the lower state tipping fees reflect the continued use of older, long-established landfills.
These landfills were built before RCRA regulations went into effect on October 9, 1991, and,
thus, do not incur RCRA compliance costs. Landfills built after October 9, 1991, tend to be more
costly than their older counterparts because they must incorporate liner systems as required
under RCRA. Engineering estimates of costs for RCRA compliance suggest that small landfills
will become prohibitively expensive to build and operate. Larger landfills—those that receive
more than 500 tons per day (TPD)—allow these fixed compliance costs to be spread over much
larger volumes of waste. RCRA compliance costs do not rise proportionally with the tonnage of
waste received; therefore, RCRA-imposed costs are lower on a per ton basis in larger landfills.
How were the estimated state tipping fees for landfills built after October 1991 determined? A
$24 per ton tipping fee was assumed, based on the recent study The Role of Recycling in
Integrated Solid Waste Management to the Year 2000, prepared by Franklin Associates for Keep
America Beautiful (Franklin/KAB study). The study estimated the revenue needed to cover the
total capital and operating costs of a 1,000 TPD landfill built after October 1991, again assuming
that only large landfills can cover the costs of RCRA compliance. Landfills serving metropolitan
areas are often located outside the urbanized area, requiring waste transportation. Landfills for
nonmetropolitan areas must serve large geographical regions in order to obtain enough waste.
For these reasons, $6 per ton was added to cover the costs of transfer and transportation for waste
sent to new, large landfills built after October 1991. Taking both factors into account, the costs
for transfer, transportation, and landfilling at facilities built after October 1991 is unlikely to fall
below $30 per ton.
The $30 per ton estimate was used as a floor for disposal costs. In states reporting average
tipping fees of less than $30 per ton, this report assumes that RCRA compliance will quickly
push these tipping fees up to $30 per ton. In areas where tipping fees are above $30 per ton, this
report assumes that the costs of RCRA compliance have already been included and no
adjustment was made. The resulting costs are shown in column four of Table 2-1. The
population-weighted national average tipping fee for landfills built after October 1991 is $38 per
ton.
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Table 2-1
Average Landfill Tipping Fees by State a
State
Alabama
Alaska
Arizona
Arkansas
California
Colorado
Connecticut
Delaware
Florida
Georgia
Hawaii
Idaho
Illinois
Indiana
Iowa
Kansas
Kentucky
Louisiana "
Maine "
Maryland L
Massachusetts "
Michigan ^
Minnesota
Mississippi
Missouri "
Montana
Nebraska
Nevada
New Hampshire
New Jersey
New Mexico
New York
North Carolina
North Dakota
Ohio
Oklahoma
Oregon
Pennsylvania
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Vermont
Virginia
Washington "
West Virginia
Wisconsin
Wyoming
TOTAL °
Population
4,040,587
550,043
3,665,228
2,350,725
29,760,021
3,294,394
3,287,116
666,168
12,937,926
6,478,216
1,108,229
1,006,749
11,430,602
5,544,159
2,776,755
2,477,574
3,685,296
4,219,973
1,227,928
4,781,468
6,016,425
9,295,297
4,375,099
2,573,216
5,117,073
799,065
1,578,385
1,201,833
1,109,252
7,730,188
1,515,069
17,990,455
6,628,637
638,800
10,847,115
3,145,585
2,842,321
11,881,643
1,003,464
3,486,703
696,004
4,877,185
16,986,510
1,722,850
562,758
6,187,358
4,866,692
1,793,477
4,891,769
453,588
248,102,973
Tipping Fees for Landfills Built
Before October 9, 1991
$33
$80
$23
$26
$33
$17
$68
$59
$46
$25
$50
$22
$08
$28
$32
$23
$25
$20
$45
$43
$55
$30
$50
$16
$24
$35
$25
$13
$50
$77
$12
$55
$26
$28
$30
$20
$25
$44
$35
$28
$32
$30
$29
$19
$58
$35
$30
$37
$30
$10
$35
Estimated Tipping Fees for
Landfills Built After
October 9, 1991 e
$33
$80
$30
$30
$33
$30
$68
$59
$46
$30
$50
$30
$30
$30
$32
$30
$30
$30
$45
$43
$55
$30
$50
$30
$30
$35
$30
$30
$50
$77
$30
$55
$30
$30
$30
$30
$30
$44
$35
$30
$32
$30
$30
$30
$58
$35
$30
$37
$30
$30
$38
Notes:
'Goldstein, N. 1997
b
The State of Garbage in America." BioCycle. April, p. 65.
Goldstein, N. 1996. "The State of Garbage in America." BioCycle. April, p. 60.
Tipping fees for states were not reported in BioCycle and were estimated at $30 per ton.
Total tipping fee is the population-weighted average.
Assumes 'floor price' of $30 per ton. See text for an explanation of this calculation.
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2.3 Avoided Mixed Waste Collection Costs
The Franklin/KAB study developed average costs for several standard collection operations,
assuming different levels of recycling and yard trimmings collection. The cost of collecting
mixed waste in a system with no separate collection will drop after introducing separate yard
trimmings and/or recycling collections, as long as the system is rationalized with regard to
routing, equipment usage, and staffing.
Table 2-2 presents the annual costs per household for mixed waste collection, both with and
without separate yard trimmings collection. The annual dollar savings per household (shown on
line three of the table) ranges from $6.46 in nonmetropolitan areas with no recycling programs to
$12.48 in metropolitan areas with extensive recycling programs. In every case, the report
estimated that separate yard trimmings collection diverted 0.416 tons per household each year.
Total avoided collection costs per ton of diverted yard trimmings ranged from $15.50 to $30.00.
The average avoided collection cost is approximately $23 per ton of diverted yard trimmings
(line five).
Table 2-2
Avoided Mixed Waste Collection Costs Associated With Leaf and
Yard Trimmings Composting Programs
Program Stipulations
Average
Costs per house per year— no yard trimmings collection
Costs per house per year— with yard trimmings collection
Costs per house per year saved
Annual tons of yard trimmings diverted per house
Avoided collection cost per ton
$63.06
$53.44
$9.62
0.416
$23.12
Source:
Franklin Associates/Keep America Beautiful. 1994. The Role of Recycling in Integrated Solid Waste
Management to the Year 2000. Appendix H.
Less information is available on the impact of food scraps and other organic materials diversion
on mixed waste collection costs. These impacts, however, are likely to be substantial in some
circumstances. Institutions or commercial establishments that divert large portions of their waste
stream to onsite composting options, for example, are likely to realize significant savings in
mixed waste collection costs. Similarly, residential source-separated composting and mixed
waste composting programs might result in decreased mixed waste collection service or
frequency. These collection cost savings, however, have not been well documented.
10
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3. ORGANIC MATERIALS MANAGEMENT STRATEGIES
This section discusses seven organic materials management strategies—grasscycling, backyard
composting, yard trimmings composting, onsite institutional composting, commercial composting,
mixed waste composting, and residential source-separated composting. Where possible, 6 to 10
existing operations are used as the basis for reviewing each strategy. The following generic
information is provided for each strategy:
• Strategy Description. General features of the strategy are described, accompanied by
illustrative examples from existing operations.
• Technical Problems. Technical difficulties and limitations of the strategy are
discussed.
• Applicable Portion of the National Waste Stream. Information from the 7997
Update and existing programs is extrapolated to the national level to estimate the
quantity of organic materials that could be targeted annually. The applicable portion
for each strategy is estimated in isolation of other strategies.
• Costs Per Ton Diverted. Information from existing programs is used to develop
estimates of the cost per ton of organic materials diverted. Cost estimates do not
include costs to homeowners. For some pilot or low-volume programs, costs per ton
were high.
For each of the strategies reviewed in this section, Table 3-1 shows the applicable quantity of the
national waste stream targeted, estimated cost per ton diverted, annual national diversion
potential, strategy descriptions, and comments.
U. S. Environmental Protection Agency 11
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Table 3-1
National Summary of Strategy Impacts
Strategy
Grasscycling
Backyard
composting
Yard
trimmings
composting
Onsite
institutional
composting
Commercial
composting
Mixed waste
composting
Residential
source-
separated
composting
Materials
Targeted
Residential and
commercial grass
Residential yard
trimmings and food
scraps
Residential and
commercial yard
trimmings
Institutional food
scraps, select
paper grades, and
yard trimmings
Food scraps and
select paper grades
All commercial and
residential organic
waste
Select residential
paper grades, food
scraps, and select
yard trimmings
Midrange
Cost Per Ton
$1.00
$12.90
$55.00
$49.00
$72.00
$113.00
NA
Cost Per Ton
Range
$0.26
to
$7.04
$5.00
to
$15.68
$21.65
to
$88.21
$29.00
to
$98.00
$50.00
to
$144.00
$102.00
to
$126.00
NA
Applicable
Portion of the
Waste Stream
(Millions of
Tons Per
Year)
14.0
30.6
28.0
2.4
24.6
74.7
47.3
Strategy
Description
Primarily
education and
promotion
Education,
promotion, and
possibly bin
distribution
Dedicated
collection and
processing of
leaves, grass,
and brush
Institutions,
such as
universities,
correctional
facilities, and
military bases,
collect and
compost
organic
materials on
site
Dedicated
collection of
targeted
materials;
processing
done off site
Standard
garbage
collection;
separation of
compostable
waste at a
single facility;
composting of
organic
materials
Dedicated
collection of
targeted
materials;
processing at a
central facility
Comments
A time-saving
source reduction
strategy for lawn
care
Source reduction
option for those
with space to
compost at home
Well-established
strategy
Allows certain
institutions to
avoid high
collection and
disposal costs
Viable strategy
for large
commercial
generators
Several facilities
have closed due
to technical
problems
Limited
experience with
this strategy in
the United States
12
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3.1 Grasscy cling
3.1.1 Strategy Summary
• Strategy Description. Residential, commercial, and institutional establishments are
encouraged to leave grass clippings on the lawn after cutting rather than bagging and
setting them out for collection. This strategy might include both public education and
financial incentives to reduce the cost of mulching lawn mowers or the equipment
required to retrofit existing nonmulching lawn mowers.
• Technical Problems. Heavy clippings left on the lawn can block sunlight and
effectively smother the lawn. Educational information must address this point.
• Applicable Portion of the National Waste Stream Diverted. Fourteen million tons
of grass are generated annually by the residential, commercial, and institutional
sectors.
• Costs Per Ton Diverted. Midrange costs for grasscycling education programs are
approximately $1 per ton of grass diverted.
3.1.2 Strategy Description
Grasscycling programs consist primarily of promotion and public education efforts. Press
releases, brochures, newspaper advertisements, and radio and television spots are often used to
promote grasscycling. Local governments often promote grasscycling by example. In New York
City's 'Leave-It-On-The-Lawn' program, for example, city workers leave grass clippings on the
city's parks and other lawns whenever feasible. Other organizations that often promote
grasscycling include schools, community groups, garden clubs, landscape businesses and
associations, garden centers, and lawn mower manufacturers and retailers. In some cases, lawn
products manufacturers have become sponsors of programs through model lawn demonstrations,
workshops, and cooperative advertising.
Examples of community grasscycling programs are provided below:
• Southeastern Oakland County Resource Recovery Authority (SOCRRA),
Michigan. The authority mails and hand-delivers grasscycling flyers and developed
fact sheets for residents interested in learning more about grasscycling.
• Pinellas County, Florida. Grasscycling establishments receive T-shirts, bumper
stickers, and signs for their lawns. Brochures were distributed to nurseries and
landscaping companies. In addition, two 30-minute video programs were made and
shown on the University of Florida's public access channel.
• Milwaukee, Wisconsin. Milwaukee's 'Just Say Mow' program encourages
grasscycling through television commercials, radio and newspaper ads, and yard
festivals in which the city shows residents the benefits of mulching and composting
grass clippings.
• Dubuque, Iowa. Shortly after Dubuque started charging for pickup of grass clippings
in 1994, the city developed a unique program that offers a $25 rebate to residents who
purchase mulching mowers.
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Organic Materials Management Strategies
• Islip, New York. The first year of Islip's grasscycling program included creating and
distributing a video, sending out three direct mail pieces, and giving away several
mulching mowers.
• Huntington Woods, Michigan. This city does not collect grass clippings, and it
distributes brochures on grasscycling to educate residents.
3.1.3 Technical Problems
Leaving grass clippings on the lawn is not harmful when mowing is frequent enough to produce
fine clippings or when a mulching mower is used. Still, heavy clippings left on the lawn can block
sunlight and smother the lawn. Educational information must address this issue.
3.1.4 Applicable Portion of the National Waste Stream Diverted
The general category of waste addressed by grasscycling is yard trimmings. Thus, estimating
national potential for grasscycling begins with the yard trimmings tonnage. According to the 7997
Update, about 28 million tons of yard trimmings are generated annually. Data in the 7997 Update
also show that approximately 50 percent (14 million tons) of yard trimmings are grass clippings.
The applicable portion of yard trimmings that could potentially be targeted by grasscycling
programs, therefore, is 14 million tons (or 28 million tons times 50 percent).
3.1.5 Costs Per Ton Diverted
For the seven grasscycling programs analyzed in Table 3-2, total program costs for 5 years
ranged from $10,000 in Dubuque, Iowa, to $300,000 in Islip, New York.
Staff time required to increase public education and develop outreach brochures often represents
the majority of costs incurred, but most grasscycling program coordinators do not dedicate all of
their time to grasscycling. For rebate programs, the majority of program costs are spent on the
rebates. The cost of developing and distributing brochures and advertisements is relatively small
and is commonly part of the budget for other recycling and composting efforts taking place in a
municipality.
Cost per ton diverted through grasscycling programs can be calculated as program cost per ton
diverted in the first year. Once residents have been educated about grasscycling (the startup program
cost), however, they presumably do not need to be reeducated each year. We assume, therefore, the
cost of educating a given generator to grasscycle is incurred only one time, and the program's
impact (i.e., the quantity of waste diverted) lasts for 5 years before additional education or outreach
is needed. This might be a reasonable estimate since most generators are likely to continue
grasscycling after an initial training period and because of the low transient nature of the residents
who usually participate in the programs.
The average cost per ton diverted was amortized over 5 years to arrive at an estimated average cost
of $1.03. Of the seven programs analyzed, costs per ton ranged from a low of $0.26 per ton in
Montgomery County, Ohio, to a high of $7.04 per ton in Dubuque, Iowa. The higher cost in
Dubuque is the result of the city's innovative program of rebating $25 to each resident who
purchases a mulching mower.
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Organic Materials Management Strategies
Table 3-2
Grasscycling Program Costs
Location
Dubuque, Iowa
Huntington Woods, Michigan
Islip, New York
Milwaukee, Wisconsin
SOCRRA, Michigan
Pinellas County, Florida
Montgomery County, Ohio
AVERAGE
Tons of Grass
Diverted
Annually a
284
450
20,000
29,677
9,000
48,889
25,000
5-Year Program
Costs r
$10,000
$10,500
$300,000
$200,000
$55,000
$80,000
$32,000
Program Costs Per
Ton Per Year
(Over 5 Years)
$7.04
$4.67
$3.00
$1.35
$1.22
$0.33
$0.26
$1.03
Notes:
aTons of grass diverted in all locations except Pinellas County and Milwaukee are estimated based on reported reductions in
quantities of grass collected, processed, or disposed of after implementation of grasscycling programs. Tons of grass diverted in
Pinellas County and Milwaukee are estimated based on responses to surveys conducted on residential participation in local
grasscycling.
Reported budgets for grasscycling programs.
3.2 Backyard Composting
3.2.1 Strategy Summary
• Strategy Description. Backyard composting of select organic materials is promoted
through outreach, bin subsidization, education, and training.
• Technical Problems. Possible technical problems include odors, flies, pests, and
undersized bins. Proper education and bin selection can mitigate, and possibly even
eliminate, these difficulties.
• Applicable Portion of the National Waste Stream Diverted. The residential sector
generates 7.9 million tons of food scraps and 22.7 million tons of yard trimmings
annually. Some programs also target other organic materials such as select paper
grades.
• Costs Per Ton Diverted. Midrange costs of $12.90 per ton diverted are incurred for
public education and bin subsidization.
3.2.2 Strategy Description
Elements of backyard composting programs might include outreach, bin subsidization, and
educational workshops.
Backyard composting program outreach efforts often include distribution of flyers and brochures,
production of videos and radio advertisements, and informational displays at local events, public
gardens, and gardening stores. To encourage greater participation, many programs subsidize the
purchase of backyard composting bins. Some smaller municipal programs also provide education to
householders on how to build bins from chicken wire, wood pallets, or other materials.
U.S. Environmental Protection Agency
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Organic Materials Management Strategies
Many municipalities organize training programs such as master composter programs. In these
programs, a compost specialist trains a group of volunteers, who themselves become master
composters. They in turn train others in the community on proper composting techniques. Other
municipalities produce show-and-tell programs. These programs include demonstration gardens and
composting education in local school science curricula, which allows children to learn about
composting in the classroom and then bring the knowledge home to teach to their families.
Staff needs for a successful backyard composting program depend on the size of the community and
on whether bins are being distributed. Many municipalities have recycling coordinators or other
staff who spend a certain percentage of their time encouraging and promoting backyard composting,
while large-scale programs tend to have coordinators who work full time on the program.
Volunteers often do some of the work; the monetary value of their time is estimated by the National
Backyard Composting Program at less than $1 per ton diverted.3
Below are descriptions of specific backyard composting programs implemented by agencies
throughout the nation.4 The programs range from extensive bin subsidies, technical assistance, and
outreach efforts to programs that emphasize primarily education and outreach.
• Alameda County, California. Alameda County initiated its program in 1990. It
distributes bins at a discounted price, has a master composter program, holds
composting workshops at a permanent demonstration garden, and offers a composting
education component as part of a school program. The program is coordinated by 5.5
full time equivalent (FTE) staff, and 80 volunteers provide additional support.
• Olympia, Washington. Olympia began its program in 1993. A key component of the
program is selling composting bins at wholesale prices to residents who complete a
free backyard composting workshop. Olympia also has a demonstration garden
sponsored by the state as an educational tool, and the city has developed a full range
of free composting brochures. Staff time for this comprehensive program amounts to
only 10 percent of one FTE staff per year but is supplemented by over 830 hours of
volunteer labor per year.
• Palm Beach County, Florida. Palm Beach County initiated its program in 1993.
Subsidized compost bins are sold to the public at publicized events. The county also
has a master composter program, but it is provided and paid for by a separate service
at no cost to the county. Staff time for the county program costs $22,000 per year.
• Glendale, California. Glendale began its program in 1991. The city gives away
composting bins and aeration tools at no charge to residents who attend a free 1-hour
workshop. The staff time for Glendale's program amounts to 6 percent of one FTE
per year as well as a total of 40 hours of volunteer assistance.
• East Chicago, Indiana. East Chicago began its program in 1994. Free bins and
composting workshops are the backbone of the program. Fifty percent of one FTE
and 800 hours of volunteer labor provide the staff for this program.
3 Composting Council. 1996. Cost-Benefit Analysis of Home Composting Programs in the United States. Prepared by Applied Compost
Consulting, p. 7.
4 Based on information reported in Cost-Benefit Analysis of Home Composting Programs in the United States.
16 U. S. Environmental Protection Agency
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Organic Materials Management Strategies
• Amherst, Massachusetts. Amherst began its program in 1991. Key components of
the program are bin distribution, workshops, brochures, books, and school programs.
Much of the work is provided through volunteer assistance, as only $900 of the
budget is allotted to pay for staff, workshops, and a hotline.
• Austin, Texas. Austin's backyard composting program is administered by the Austin
Community Gardens. Training and education are the primary focus of the program.
Each year 25 students are trained as master composters, each of whom is encouraged
to contribute 24 hours of volunteer time to the program.
3.2.3 Technical Problems
The primary technical problems associated with backyard composting include odors and pests.
Odors can be emitted when the compost pile is not turned often and anaerobic decomposition
occurs. Pests (e.g., raccoons, rats, and mice) might enter compost bins if they are not properly
enclosed and/or secured.
In order to avoid these problems and ensure that the right materials are composted, technical
assistance is essential. If municipalities do not adequately educate and promote continual, correct
use of a composting pile, 'individuals [might] experience minor problems and refuse to ever
contemplate composting again. This, in turn, could impact other waste diversion efforts attempted
by the municipality.'5
3.2.4 Applicable Portion of the National Waste Stream Diverted
In most cases, backyard composting applies to two major components of the waste stream—food
scraps and yard trimmings. The 7997 Update indicates that 21.9 million tons of food scraps and 28
millions tons of yard trimmings are generated by the residential and commercial sectors.
Approximately 72 percent (15.8 million tons) of food scraps are compostable.6 This includes all
food scraps except meat, fish, cheese, milk, and fats and oils. In addition, the 7997 Update estimates
that 50 percent (11 million tons) of food scraps are generated by the residential sector. The portion
of food scraps, therefore, that is generated by the residential sector and that is compostable is about
7.9 million tons (or 21.9 million tons times 36 percent [50 percent times 72 percent]).
The 7997 Update reports that about 90 percent (25.2 million tons) of yard trimmings come from
the residential sector. Making an allowance of 10 percent (2.5 million tons) for large items—tree
trunks and large limbs—that are not easily compostable, about 22.7 million tons of yard
trimmings are available for backyard composting (or 28 million tons times 81 percent [90
percent times 90 percent]).
Based on the above, a total of 30.6 million tons of organic waste could be targeted by backyard
composting programs including 7.9 million tons of food scraps and 22.7 million tons of yard
trimmings. This estimate is likely to be conservative since some areas also encourage composting of
select paper and other organic materials.
Metro Toronto. Report 19 of the Management Committee, p. 8.
6 Rathje, W. The Garbage Project Composition Analyses.
U. S. Environmental Protection Agency 17
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Organic Materials Management Strategies
3.2.5 Costs Per Ton Diverted
The costs of backyard composting programs generally fall into four categories: staffing, public
education and outreach, bin purchasing, and bin distribution. Education efforts often continue well
into the project, and some communities provide home visits and instruction on composting
techniques by experts for any interested residents. Frequently, bins are subsidized by grants and
homeowners make up the difference. Bins are a significant element of program costs in those
communities that provide or subsidize bins.
Municipally sponsored backyard composting program costs can vary significantly. Some
programs include significant startup costs associated with bin subsidization and initial education
and outreach programs. In these cases, the costs for initiating the programs are high compared to
the amount of waste diverted after the first year. But since bins typically last for 7 years (and
some are now even warranted for up to 25 years) and only minimal additional funding might be
needed from the municipality to sustain the program, program costs decrease over time.
There is a wide range of compost bin prices; the simplest units can be as inexpensive as $10,
while the largest and most expensive can cost as much as several hundred dollars. Prices vary
depending on how many bins are purchased at once; most municipalities have been able to
obtain bins at wholesale prices by purchasing bulk quantities. In general, backyard composting
bin costs range from $25 to $50.
Typical backyard composting program costs are provided in Table 3-3 for the various programs
described in Section 3.2.2. Tonnage impacts and costs per ton diverted assume 7 years of program
impact based on the assumed life of a bin.7
The programs are organized in Table 3-3 based on whether or not bin subsidies are provided. Bin
subsidy programs tend to cost an average of $15.68 per ton diverted over their useful life, while
programs emphasizing education cost an average of $5 per ton diverted. The average cost of all
backyard composting programs is about $12.90 per ton diverted.
7 Seven years is the standard bin depreciation time.
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Organic Materials Management Strategies
Table 3-3
Backyard Composting Program Costs a
Bin Subsidy Programs'3
Alameda County, California
Palm Beach County, Florida
Amherst, Massachusetts
Glendale, California
Subtotal
Education Programs
Austin, Texas
East Chicago, Indiana
Olympia, Washington
Ann Arbor, Michigan
Subtotal
TOTAL AVERAGE COST
Program Tons
Diverted
28,000
9,737
1,750
7,077
46,564
379
1,400
1,500
13,000
16,279
7-Year
Program Costs
$537,600
$135,500
$13,803
$43,150
$730,053
$20,000
$24,400
$11,530
$25,000
$80,930
Average
Program Costs
Per Ton
$19.20
$13.92
$7.89
$6.10
$15.68
$52.77
$17.42
$7.68
$1.92
$4.97
$12.90
Notes:
a All data in this table are based on the Composting Council's Cost-Benefit Analysis of Home
Composting Programs in the United States, 1996.
b Although no additional costs are assumed for years 2 to 7, there may be some additional costs if
educational workshops, a helpline, or technical assistance are provided.
3.3 Yard Trimmings Composting
3.3.1 Strategy Summary
• Strategy Description. Yard trimmings (e.g., leaves, grass, and brush) are collected
and composted at a central location.
• Technical Problems. Odors from centralized compost facilities are the primary
technical problem, but stormwater management, litter control, and siting and
permitting issues can be of concern as well.
• Applicable Portion of the National Waste Stream Diverted. Twenty eight million
tons of leaves, grass, and brush are generated annually by the residential, commercial,
and institutional sectors.
• Costs Per Ton Diverted. Midrange costs for the programs described in this section
are approximately $66 per ton diverted ($44.37 per ton for collection and $21.65 per ton
for composting).
U.S. Environmental Protection Agency
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Organic Materials Management Strategies
3.3.2 Strategy Description
3.3.2.1 Collection Programs
Yard trimmings composting programs represent the most widespread and well established
composting strategy. There are many ways to collect yard trimmings, ranging from sophisticated
curbside collection programs to simple drop-off programs.
Two general methods of curbside collection are bulk collection and bag collection. Bulk collection
programs often rely on vacuum machines, front-end loaders, or mobile chippers to collect loose
leaves or brush that are raked to the curb or into the street. Crew size for this operation is generally
three to five laborers per vehicle. Bag collection operations usually rely on existing packer fleets
and crews (typically two to three laborers) to collect yard trimmings. Brush, when collected
curbside, is often either chipped on the street using a mobile chipper or collected in bundles with a
packer truck and taken to a composting site where it is chipped.
Drop-off systems can replace curbside collection completely or cover periods of the year when there
is no curbside collection. If the composting facility is centrally located, the drop-off can simply be
set up on site. In many cases this is not possible; therefore, secondary sites, such as at a
municipality's department of public works, are created. A rolloff container can be used for
temporary storage; when full, it can be hauled to the nearest compost facility.
3.3.2.2 Composting Facilities
Yard trimmings composting facilities range from low-technology operations, where piles of leaves
are turned periodically with front-end loaders, to high-technology operations, where size reduction
equipment, dedicated windrow turners, and screening equipment are used. An advantage to using
high-technology processing methods, aside from producing a higher quality product, is that compost
can be produced and moved off site within a year, making space for the following year's material.
Low-technology operations generally require more time to complete the composting process and
consequently more land area to accommodate more than one season's material. Available land,
therefore, is a key criterion for determining the most appropriate composting method for a given
site.
Many public works departments use front-end loaders for a variety of purposes; therefore, a portion
of the equipment time can be allocated to the composting program. Capital and operating costs for
this equipment can be considered proportional to the volume of the total material handled by the
front-end loader or to the percentage of time the equipment is working at the composting site. In
general, the cost of a windrow turner increases with increases in capacity, and operating costs
increase with the complexity of the model.
If brush is accepted at the site, it must be reduced in size prior to composting. Small quantities of
brush can be processed through a chipper, but a tub grinder or wood scrap processing equipment is
needed to process large quantities. Brush chips can be used for landscaping or can be composted
with high nitrogen material such as grass. Leaves and grass also can be size-reduced in a tub grinder
to reduce the time required to complete the composting process.
Expensive equipment, such as tub grinders or compost screens, can be purchased jointly and shared
among communities. Even windrow turners can be shared, although they must be transported from
site to site more frequently than the other equipment.
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Organic Materials Management Strategies
3.3.3 Technical Problems
3.3.3.1 Collection Systems
Disadvantages of bulk collection systems include contamination of leaves by street trash and oil,
leaf piles that blow into the streets, and leaf fires caused by hot catalytic converters. Bulk
collection methods usually require scheduled collection and associated parking bans if needed.
Disadvantages of the bag collection system include the cost of the paper bags, which is somewhat
higher than plastic bags in most locations. Additional effort is required of homeowners to purchase
and fill the bags. Finally, bagged leaves take somewhat more time to compost if no grinding
equipment is used because the heavy bag itself creates more material to process.
Drop-off programs are not as convenient as curbside collection strategies; therefore, participation
and diversion rates for drop-off programs might be lower.
3.3.3.2 Facilities
Odor can be a problem at yard trimmings composting facilities. Factors that contribute to odor
generation include types of materials collected, management issues, siting, and climatic conditions.
Grass clippings in particular become anaerobic and emit offensive odors very quickly due to their
high moisture and nitrogen content. It is critical to process grass clippings as soon as possible after
delivery to avoid odor problems and ground-water contamination. While small amounts of grass
provide necessary nitrogen to accelerate the composting process and produce finished compost with
desired nutrient content, too much grass has a decidedly negative impact on composting sites. This
points to the logic of promoting grasscycling programs in conjunction with leaf collection.
While grass is the primary contributor to odor, leaf composting alone also can produce odors when
improperly managed. It is advantageous to site composting facilities far away from residential areas,
as odorous compounds get diluted with distance; otherwise, siting and permitting battles can arise.
In addition to odor problems, stormwater management and litter problems might be of concern
and must be planned for accordingly.
3.3.4 Applicable Portion of the National Waste Stream Diverted
Yard trimmings composting programs target leaves, grass, and brush generated primarily by the
residential sector. According to the 7997 Update., approximately 28 million tons of these materials
are generated annually. Ninety percent (25.2 million tons) is generated by the residential sector,
while the remaining 10 percent (2.8 million tons) is generated by the commercial sector.
3.3.5 Costs Per Ton Diverted
A recent study of 500 U.S. municipalities provides a median overall diversion rate through yard
trimmings collection (both curbside and drop-off) of about 12 percent.8 According to the 7997
Update, \1> A percent of the waste stream is comprised of yard trimmings. The 12 percent diversion
8 Skumatz, L.A. 1996. Nationwide Diversion Rate Study-Quantitative Effects of Program Choices on Recycling and Green Waste Diversion:
Beyond Case Studies. Skumatz Economic Research Associates, Inc. July. p. 13. The figure of 12 percent includes programs that already had some
sort of backyard composting program in place, which would tend to lower the diversion rate of actual yard trimmings collection programs. Thus,
this figure should be viewed as slightly conservative.
U. S. Environmental Protection Agency 21
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Organic Materials Management Strategies
rate suggests that, on average, yard trimmings composting programs divert 90 percent (12 percent
divided by 13.4 percent) of all yard trimmings generated in a given area.
A variety of factors influence the cost of yard trimmings composting programs including the
collection strategy used (e.g., drop-off or curbside), the materials targeted (e.g., leaves, grass,
brush, or some combination thereof), the frequency of collection, the quantity of yard trimmings
generated, the technology used for turning compost windrows or grinding brush (e.g., dedicated
equipment versus existing or shared resources), and numerous other factors.
One study of 60 randomly selected U.S. cities with populations of over 25,000 examined the
relationship among collection frequency, diversion rates, and costs. That study yielded an
average cost of $66.56 per ton collected by programs that divert between 10 and 19.9 percent of
the municipalities' waste stream.9 More mature curbside programs, which target 20 percent or
more of the municipalities' waste stream, average $53.67 per ton collected.
To develop a midrange national cost estimate for yard trimmings collection, it was necessary to
consider the relative quantities and costs of yard trimmings drop-off versus curbside collection
programs. Curbside collection programs divert approximately two times the amount of yard
trimmings as drop-off collection programs. A 2:1 curbside to drop-off diversion ratio, therefore,
is used in conjunction with the cost per ton collected by curbside versus drop-off programs.10 For
drop-off programs, the cost of collection is assumed to be $0 because individuals who drop off
their yard trimmings at the compost facility bear the cost of collection. For curbside collection, a
cost of $66.56 per ton collected is assumed based on the study referenced above of 60 randomly
selected cities that divert 10 to 19.9 percent of their waste stream through curbside yard
trimmings collection programs. This estimate is conservative because the same study indicated
that programs that divert larger quantities of their waste stream cost less per ton collected.
Combining the curbside collection cost with the drop-off collection cost at a 2:1 ratio (to reflect
the relative quantities of materials collected by curbside and drop-off programs) yields a
midrange estimate of $44.37 per ton collected by yard trimmings programs.
Whether the yard trimmings are brought to a composting facility via curbside collection or dropped
off by residents or commercial landscape contractors, once at the facility, further costs will be
incurred as the material is turned into finished product. A recent BioCycle article presented the
results of a survey of seven public composting facilities that process from 2,000 to 23,500 tons per
year of feedstock. This survey revealed an average total cost (capital plus operating) of $21.65 per
ton, as shown in Table 3-4.
Yard trimmings diversion costs for the programs analyzed range from a low of $21.65 per ton
diverted for programs that rely on drop-off collection to a high of $88.21 per ton diverted for
programs that use more extensive curbside collection and processing operations ($66.56 for
collection and $21.65 per ton for composting). The assumed national midrange cost of yard
trimmings composting is $66.02 per ton diverted ($44.37 for collection and $21.65 for composting).
9 Stevens, B. 1995. "Yard Debris: The Relationship Among Collection Frequency, Costs, and Diversion Rates."Resource Recycling. January, p.
29. A followup telephone conversation on October 21, 1996, confirmed that the cities were a mix of public and private collection and that there
were some vacuum programs included. Also, it confirmed that administration and overhead costs were included as part of the calculations.
10 Skumatz, L.A. 1996. Nationwide Diversion Rate Study-Quantitative Effects ofProgram Choices onRecycling andGreen Waste Diversion:
Beyond Case Studies. Skumatz Economic Research Associates, Inc. July. p. 13.
22 U. S. Environmental Protection Agency
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Organic Materials Management Strategies
Table 3-4
Select Windrow Compost Facility Throughput and Costs
Facility a
St. Petersburg, Florida e
Des Moines, Iowa d
Atlantic County, New Jersey
Utilities Authority
Lehigh County, Pennsylvania
Three Rivers, Michigan e
Bluestem SWA, Cedar Rapids,
Iowa c
Bozeman, Montana
WEIGHTED AVERAGE f
Throughput
(Tons Per
Year)
16,600
23,500
22,000
17,000
2,700
70,000
2,000
Total Costs
Per Year
$424,960
$528,750
$484,000
$314,500
$46,440
$784,000
$16,000
$1,814,650
Operating
Costs Per
Ton
NA
MA
$11.80
$8.10
NA
$7.00
$6.50
Capital
Costs Per
Tonb
NA
NA
$10.20
$10.40
NA
$4.20
$1.50
Total Costs
Per Ton
$25.60
$22.50
$22.00
$18.50
$17.20
$11.20
$8.00
$21.65
Source:
Steuteville, R. 1996. "How Much Does It Cost to Compost Yard Trimmings?" BioCycle, September, p. 40.
Notes:
a All operations utilize open air windrows with turning.
b Capital costs generally do not include land.
0 Two-thirds of throughput consists of nonyard trimmings from the commercial sector.
d Cost estimate is based on an average of 22,000 to 25,000 tons per year throughput.
e Operating and capital costs are calculated together.
f The weighted average is based on tonnage throughput, and does not include the Bluestem SWA facility because the large majority
of its feedstock is nonyard trimmings.
3.4 Onsite Institutional Composting
3.4.1 Strategy Summary
• Strategy Description. Institutions process food scraps, paper, and yard trimmings at
an onsite composting operation.
• Technical Problems. Regulatory requirements are the greatest difficulty faced by
institutional composting sites.
• Applicable Portion of the National Waste Stream Diverted. Universities,
correctional facilities, schools, hospitals, and military bases generate 2.4 million tons
of food scraps, paper, and yard trimmings annually.
• Costs Per Ton Diverted. Midrange cost is $49 per ton of material diverted.
3.4.2 Strategy Description
Institutions, such as universities, schools, hospitals, correctional facilities, and military installations,
are uniquely suited to composting because they typically generate large quantities of organic
materials and have land available for composting. Institutional composting can reduce disposal costs
or, as is the case at many universities, provide opportunities for research and development of new
compost technologies. Examples of composting operations at correctional facilities, universities,
military installations, and other institutions are provided below.
U.S. Environmental Protection Agency
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Organic Materials Management Strategies
3.4.2.1 Correctional Facilities
Low-technology institutional composting occurs at the Georgia Diagnostic and Classification
Center (GDCC) and the New York State Department of Corrections (NYDOC), which has 30
operating composting programs at correctional institutions throughout New York.11 Materials
collected for the programs include food scraps, brush, wood scraps, and some paper. Average
diversion rates reported by NYDOC are approximately 25 to 30 percent of the total waste generated.
Inmates collect materials using existing equipment that was formerly used primarily for garbage
disposal. Materials collected are composted in open windrows on concrete pads. An animal feeder is
used to mix the compostables, a skid steer loader is used for turning the piles, and, in some cases,
the finished product is screened with a trommel screen. Finished compost is then used in prison
landscape and horticultural applications as well as in community projects.12
A more high-technology approach is employed by the Rikers Island correctional facility in New
York City. 3 This approach uses an in-vessel compost technology that is suitable for institutions
with limited space. The program targets food scraps, corrugated, and a limited quantity of pallets.
Approximately 200 yellow 44-gallon containers are placed near feeding lines, in food
preparation areas (e.g., near vats and in vegetable preparation locations), and in cleanup areas of
the kitchen. After each meal, the yellow containers are emptied by inmates into one of four 12-
cubic-yard containers. These containers are collected 5 days a week by the New York
Department of Sanitation and delivered to the centrally located compost facility. Corrugated is
collected from kitchen loading docks by inmate work crews. The facility is currently operated
under contract to the New York Department of Sanitation by Wheelabrator Water Technologies.
Finished compost is used by the Rikers Island Farm Project. The operation is expected to handle
about 4,000 tons of food scraps and corrugated cardboard annually when it is fully operational.14
3.4.2.2 Universities
Universities often generate large quantities of organic waste. A feasibility study for a composting
project at Tufts University in Medford, Massachusetts, estimated that a typical undergraduate
generates approximately 60 pounds of food scraps annually.15
The University of Vermont (UVM) implemented a pilot composting program in 1992. During 1993,
approximately 17 percent of the UVM waste stream was co-composted with manure. Compostable
materials diverted from the university's waste stream included 272 tons of mixed paper (68 pounds
11 Marion, J. 1994. "Correctional System Wins With Composting and Recycling."BioCycle. September, p. 30.
12 Based on telephone conversations with Glen Sluggs of GDCC and Jim Marion of NYDOC.
13 Rikers Island is operated by the New York City Department of Corrections, which is separate from the New York State Department of
Corrections.
14 The Rikers Island composting facility commenced operations in September 1996.
15 This estimate was derived using food scraps per diner per meal multiplied by the number of meals over the course of the school year divided by Hie
number of undergraduate students. In fact, some faculty, graduate students, and staff use the dining services, although the numbers were not estimated.
In addition, an unknown number of undergraduate students at Tufts eat their meals outside of university dining facilities. This information is based on a
waste audit performed by Caroline Ganley and Peter Allison and provided by Sarah Creighton of Tufts University.
24 U. S. Environmental Protection Agency
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Organic Materials Management Strategies
per student) and 78 tons of food preparation scraps (19.5 pounds per student). Finished compost was
used to fertilize animal feed crops.16
The University of Maine at Orono (UMO) began composting leaves, brush, and manure in a
preliminary way in 1990. By 1992, UMO was composting dining hall food scraps, yard trimmings,
chopped brush, and lumber scraps. The university began to reach out to surrounding communities
by accepting leaves and found that it incurred no additional costs by doing so. When additional
surrounding communities became interested in starting composting programs, UMO and four
communities applied for a capital investment grant from the Maine Waste Management Agency. In
this way, the program was able to generate the materials needed to support a relatively large,
sustained composting program.1?
3.4.2.3 Military Installations
Some military installations also have begun composting operations, although the targeted
materials seem to be primarily limited to yard trimmings and wood waste. The Air Force has
initiated many composting operations since it issued a policy statement, in May 1994, requiring
each installation to operate an onsite facility or participate in composting through a regional
program. When a survey of the 114 Air Force bases was conducted in 1994, 35 had yard
trimmings programs or planned to have them in the near future. Nine of these had onsite
composting facilities operating; the rest were either off site or in the planning stages.
Kelley Air Force Base in Texas provides one example of a planned onsite composting
operation.18 The program targets 700 tons of pallets and 100 tons of yard trimmings generated
annually. A tub grinder is used to shred pallets, and a front-end loader is used for turning
windrows.
3.4.2.4 Other Institutions
Other institutions, such as hospitals and primary and secondary schools, also have the potential for
diverting organic materials. Two elementary schools in Concord and Conway, Massachusetts, for
example, have started composting food scraps from the lunch rooms in composting bins managed
by students. Although this is primarily an educational project for the students, Concord's program
diverted an estimated 15 pounds per student in its first year of operation. A higher technology
alternative is in operation at the London, Ontario, psychiatric hospital. This facility recently started
using an onsite enclosed in-vessel composting system. The diversion of material is projected to be
over 1,000 pounds per hospital bed per year.
In February 1995, the Canadian Department of Natural Resources (NRCan) in Ottawa implemented
a compost operation using a small in-vessel composting system. While its cafeteria alone generated
about 120 pounds of food scraps per day, NRCan decided to bring in food scraps from other
institutions in the region because it had a throughput capacity of 750 pounds per day. Wood chips
16 Personal communication with Dennis Miller, University of Vermont Solid Waste Manager.
17 Wilderson, S. 1996. "University Composting Program Serves Four Local Communities."5zoCyc/<3. August, pp. 76-77.
18 United States Air Force. 1994. Yard Waste Composting Programs: Current and Planned Air Force Initiatives. Civil Engineer Support Agency,
Tyndall Air Force Base, Florida.
U. S. Environmental Protection Agency 25
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Organic Materials Management Strategies
are added as a bulking agent to the food scraps. NRCan pays to have the wood delivered. The in-
vessel unit produces six 95-gallon drums of compost a week.19
3.4.3 Technical Problems
Institutional composting facilities, including small onsite systems, are often required to undergo the
same regulatory and siting process as large solid waste disposal and processing facilities. These
permit requirements probably represent the single largest barrier to widespread composting by this
sector.
3.4.4 Applicable Portion of the National Waste Stream Diverted
Table 3-5 shows the potential for diverting organic materials from several types of institutions using
unit diversion rates estimated in this section. Assuming all institutions in each category compost,
this analysis suggests that approximately 2.4 million tons of organic materials could be diverted
from institutions.
Table 3-5
Potential Onsite Institutional Composting Diversion Rates
Institutions
Population
Per-Capita Diversion
(Annual Pounds Per Population)
Food Paper Yard
Total
Total Diversion (Tons)
Food Paper
Yard
Total
Correctional
910,080
794
140
30
964
361,302
63,706
13,619
438,627
Hospitals
1,158,000
500
100
30
630
289,500
57,900
17,329
364,729
Military
1,397,000
30
30
0
0
20,906
20,906
Schools
50,709,000
15
30
45
380,318
758,860
1,139,178
Universities 9
7,065,703
40
68
30
138
140,431
240,234
105,738
486,403
TOTAL
361.840
916.453
2.449.843
Notes:
a Based on Statistical Abstract of the United States: 1995. Inmate population includes federal and state prisoners. University population
includes full-time undergraduate students only. Hospital population reflects number of beds at all hospitals. Military population includes active
military personnel located in the United States.
b Data on per-capita yard trimmings diversion was not available. Thirty pounds per capita is estimated based on information reported in the
U.S. Air Force's Yard Waste Composting Programs: Current & Planned Air Force Initiatives, 1994.
0 Diversion estimate for food scraps is based on the average of Rikers and NYDOC data. Estimate for paper is based on Rikers data.
d Diversion estimate is based on one-half of the London, Ontario, projection.
e No data were available on military food scraps or paper composting programs; only yard trimmings composting is assumed.
f Food scraps estimate is based on Concord, Massachusetts, elementary school data. No data were available for school paper generation.
g Diversion estimate for food scraps is based on the average of Tufts and UVM data. Estimate for paper is based on UVM data.
3.4.5 Costs Per Ton Diverted
Table 3-6 provides a summary of the cost of the five institutional programs for which capital and
operating cost information is available.20
Sinclair, R.G. 1996. "Managing Food Residuals Through On-Site Composting."BioCycle. January, pp. 34-36.
20 The sources of this information are given in the footnotes to the text of the corresponding section (e.g., universities).
26
U.S. Environmental Protection Agency
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Organic Materials Management Strategies
For correctional facilities with low-technology composting operations (NYDOC and GDCC), the
combination of inmate labor and existing equipment reduces collection and operation costs
significantly. Much of the cost estimated for the Rikers facility is due to site-specific constraints that
would not necessarily apply to high-technology facilities in other locations.21
Costs for the five onsite institutional programs are organized in Table 3-6 by low-technology and
high-technology options. Weighted average costs range from $29 to $98 per ton diverted for low-
technology and high-technology operations respectively. Weighted average costs of low-technology
and high-technology operations are $49 per ton diverted.
Table 3-6
Onsite Institutional Composting Program Costs
Facility
Low-Technology
Kelley Air Force Base
GDCC
NYDOC a
Weighted Average Low-
Technology
High-Technology
NRCan
Rikers
Weighted Average High-
Technology
WEIGHTED AVERAGE"
Tons
Composted Per
Year
800
1,040
7,800
94
4,000
Capital Costs
$47,143
$11,429
NA
$5,853
$152,070
Operating
Costs
$20,000
$28,000
NA
$11,274
$230,000
Total Costs
$67,143
$39,429
NA
$17,127
$382,070
Costs Per
Ton
$84
$38
$22
$29
$182
$96
$98
$49
Notes:
a Marion, J. 1994. "Correctional System Wins With Composting and Recycling." BioCycle. September, p. 32.
b The average cost per ton is weighted based on tons of material composted per year.
3.5 Commercial Composting
3.5.1 Strategy Summary
• Strategy Description. Commercial organic materials generators—supermarkets,
restaurants, schools, and others—receive commercial collection services and separate
organic materials (e.g., food scraps and unrecyclable cardboard and paper) for
collection and composting.
• Technical Problems. Compacted food scraps can generate odorous liquids that leak
from collection vehicles. Also, the containers used to store the food scraps before
The Rikers Island facility is located on an island within a few hundred feet of the end of an active runway at LaGuardia Airport.
U.S. Environmental Protection Agency
27
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Organic Materials Management Strategies
collection can become quite odorous themselves and need to be cleaned or
exchanged, which itself can cause logistical problems.
• Applicable Portion of the National Waste Stream Diverted. The commercial
sector generated 24.6 million tons of food scraps and soiled, unrecyclable paper and
cardboard annually.
• Costs Per Ton Diverted. Midrange cost for collection and processing is estimated at
$72 per ton.
3.5.2 Strategy Description
Commercial generators of organic materials that receive commercial collection services, such as
supermarkets, food processing companies, restaurants, and schools, have the potential for diverting
large amounts of food scraps, soiled and waxed cardboard, and paper. In a supermarket, for
example, organic residues can represent 75 to 90 percent of the total waste stream.22 In schools,
restaurants, and personal care facilities, organic materials make up an average of 74 percent of the
total waste stream.23
There are several ways that commercial organic materials are collected. For larger generators,
rolloff compactors can be filled on site then hauled directly to a composting site. Smaller generators
have their materials collected more frequently by packer trucks from smaller outside containers,
such as toters or dumpsters, or by a service that swaps empty containers for full ones.
3.5.3 Technical Problems
Compactors without gaskets and packer trucks can leak substantially and create odors and messy
conditions. This problem can be alleviated by using rolloff compactors with watertight gaskets.
Another problem is encountered by haulers that collect toters or dumpsters and clean these
containers at the customers' site. The resulting wastewater must be handled appropriately. Waste
Management of Fort Worth, Texas, for example, captures the wastewater in a separate container in
the collection vehicle then dumps the water into its sewage system (for which it has a permit).24
The second wastewater handling option is to actually store the water with the organics, as is done by
Food Waste Management of Vermont. This company uses an over-the-top style truck and, thus,
does not have problems with leakage. The company does note, however, that this system increases
collect on costs.25
In an attempt to reduce the frequency with which the containers need to be cleaned, some haulers
have tried to use degradable liners to protect the container sides. In Fort Worth, Waste Management
has ordered 4,000 biodegradable bags that will be held in place in the containers with oversized
Kunzler, C., and R. Roe. 1995. "Food Composting Projects on the Rise."BioCycle. April, p.65.
23 Black, G. 1995. "Strategies for Commercial Organics Diversion." BioCycle. November, p. 63.
24 Ibid. p. 60.
25 Ibid. p. 60.
28 U. S. Environmental Protection Agency
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Organic Materials Management Strategies
rubber bands. Waste Management hopes this option will reduce the number of times the containers
require washing.
3.5.4 Applicable Portion of the National Waste Stream Diverted
The commercial sector has strong potential to contribute to the diversion of organic materials. One
9-month pilot examined collection of food scraps and soiled, unrecyclable paper and cardboard
from 51 commercial establishments including restaurants, schools, personal care facilities, a grocery
store, and others. They found that these businesses on average captured 48 percent of the materials
targeted for collection.26 Food scraps and soiled, unrecyclable paper and cardboard make up about
24.6 million tons of all material generated by the commercial sector. See Table 3-7 for a summary.
Table 3-7
Applicable Portion of the Waste Stream Available for Commercial Composting
Materials Targeted by Commercial
Organics Programs3
Tissue paper/towels
Paper plates, cups
Other nonpackaging paper
Corrugated boxes0
Milk cartons
Folding cartons
Other paperboard packaging
Bags and sacks
Wrapping papers
Other paper packaging
Food Scraps
TOTAL
% Generated by Commercial
Sources'3
40%
80%
50%
90%
50%
40%
50%
10%
10%
30%
50%
Thousands of Tons Generated by
Commercial Sources0
1,192
760
2,060
6,570
230
2,156
115
198
5
405
10,950
24,641
Notes:
Excludes yard trimmings which are assumed to be targeted by grasscycling and municipal yard trimming programs.
b Derived from Table C-1 of the 7994 Update.
c Material tonnage data from the 7997 Update is applied to percentage generated by commercial sources.
Unrecycled corrugated boxes. According to the Grocery Committee of the Food Marketing Institute (1991), retailers generate 6.6
million tons per year of food scraps and non-recyclable cardboard (soiled, wet, or waxed) at a 3:1 ratio. Therefore, the amount of
soiled corrugated boxes is calculated by dividing the total quantity of food scraps by three.
! Ibid. p. 63.
U.S. Environmental Protection Agency
29
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Organic Materials Management Strategies
3.5.5 Costs Per Ton Diverted
In the commercial sector, the costs of collection and processing are often not easily accessible, as
they are considered proprietary information. The city of Seattle, the King County Solid Waste
Division, and the Washington Department of Ecology, however, funded development of detailed
cost models for collection and processing of commercial organics as part of the Seattle/King County
Commercial Food Waste Demonstration Project.27 The collection models were based on several
factors including food scraps generation rates per employee for different types of generators,
participation rates based on survey information, efficiency of organics separation by participating
firms, collection frequency, and container weight limits. The model indicated that the quantity of
food scraps generated at each commercial site and the distance between generators had the greatest
impact on commercial organics collections costs. Collection and transport and processing cost
ranges were calculated for several service areas as shown in Table 3-8. The model also estimated
capital, operational, and maintenance costs and amortized total processing costs for standard
processing compost facility designs.28
Some examples of prices charged per ton to commercial establishments for collection and/or
processing of organic materials also are presented in Table 3-8. For large generators that can use
compactors, such as the Shop-Rite supermarket chain in northern New Jersey, the charge for
collecting organics in a 25-cubic-yard compactor depends on the distance to the composting facility
but, generally, is in the realm of $250 per haul. Given that these compactors hold 15 to 20 tons, this
results in an average charge of about $14 per ton for collection alone. The material is then delivered
to local compost facilities that charge about $36 per ton.29
27 Sasser, L. 1995. "Feasibility of Large-Scale Organics Diversion." BioCycle. October, p. 68. Cost models were developed by E&A
Environmental and Bender Consulting, Inc.
28 The model assumes use of an enclosed, aerated static pile for initial stabilization and that slightly differing technologies would be used after
initial stabilization.
29 Figures in this paragraph are based on personal communication with Tim Vogel, Manager of Environmental Affairs, Wakefern Corporation
(owner of Shop-Rite supermarkets), October 28, 1996.
30 U. S. Environmental Protection Agency
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Organic Materials Management Strategies
Table 3-8
Collection, Processing, and Combined Costs Per Ton
Collection Services
Seattle Cost Model
Downtown service area
Urban neighborhood
Suburban city
Seattle Cost Model average
Shop-Rite
Hannaford Brothers
AVERAGE COST OF COLLECTION
Reported Processing Costs
Seattle Cost Model
Shop-Rite
Hannaford Brothers
Intervale Compost Facility
Earthgro Compost
AVERAGE COST OF PROCESSING
AVERAGE COLLECTION AND
PROCESSING
Costs Per
Ton
(Low)
$34.00
$46.00
$63.00
$47.67
NA
NA
$23.00
NA
NA
NA
NA
Costs Per
Ton
(High)
$45.00
$89.00
$102.00
$78.67
NA
NA
$42.00
NA
NA
NA
NA
Costs Per
Ton
(Average)
$39.50
$67.50
$82.50
$63.17
$14.00
$43.00
$40.06
$32.50
$36.00
$18.00
$40.00
$33.00
$31.90
$71.96
Source:
Seattle Cost Model was developed by E&A Environmental Consulting and Bender Consulting for the Seattle/King
County Commercial Food Waste Composting Demonstration Project, 1995. See accompanying text and footnotes for
details on all other cost estimates.
Many generators, however, cannot or prefer not to use compactors and, thus, use a smaller-scale
approach. The food scraps from Hannaford Brothers' stores are placed in 95-gallon toters and
collected one to three times per week. The company pays $40 to $45 per ton for this service.30
Once at a composting facility, charges will vary as well. Hannaford Brothers reports being charged
$10 to $25 per ton for its material; the Intervale Compost Project in Vermont charges $40 per ton;
and the Earthgro composting facility in Lebanon, Connecticut, charges $25 to $40 per ton for food
scraps.31 What has been generally noted, however, is that composting tip fees are, in most cases, less
than half of the local disposal option.32
30 Personal communication with Ted Brown, Environmental Affairs Manager, Hannaford Brothers, October 25, 1996.
31 Op Cit. Parrel, p.62.
32 Kunzler, C., and M. Parrel. 1996. "Food Service Composting Update."BioCycle. May. p. 49.
U.S. Environmental Protection Agency
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Organic Materials Management Strategies
As summarized in Table 3-8, average costs for this strategy are assumed to be about $72 per ton
diverted. Costs per ton collected and composted range from a low of about $50 ($14 plus $36) as
reported by Shop-Rite to a high of around $144 ($102 plus $42) estimated for suburban areas by the
Seattle Cost Model.
3.6 Mixed Waste Composting
3.6.1 Strategy Summary
• Strategy Description. Mixed waste composting facilities separate MSW into
component streams for composting, recycling, and refuse disposal.
• Technical Problems. Odor problems have plagued mixed waste composting
facilities, and odor mitigation initiatives have raised mixed waste composting costs.
Emissions of harmful airborne fungi also have been reported. The compost produced
by these facilities is often contaminated by metals present in MSW, which reduces its
range of application and its value.
• Applicable Portion of the National Waste Stream Diverted In theory, this strategy
could divert all organic waste that is currently targeted for composting. This includes
28 million tons of yard trimmings, 22 million tons of food scraps, and 25 million tons
of soiled or unrecyclable paper—resulting in an annual total of 75 million tons of
material.
• Costs Per Ton Diverted. Midrange costs are estimated at $63 per ton for collection
and $50 per ton for processing for a total cost per ton of $113.
3.6.2 Strategy Description
Mixed waste composting refers to a centralized processing system that accepts mixed MSW and
separates materials into component parts for composting, recycling, and ultimate disposal. Facilities
in the United States range in capacity from 15 to 220 TPD and employ a range of technologies.
There are 12 mixed waste composting facilities operating in the country.3
Mixed waste composting once appeared to be a solid waste panacea. Mixed solid waste was
promised to be transformed into high-quality products with no modification to waste collection
systems while vastly decreasing our dependence on landfills. A number of mixed waste composting
plants were established in the United States in the 1980s with mixed results, as discussed below.
Most mixed waste composting facilities include basic preprocessing equipment such as trommels,
shear shredders, or other size reduction equipment. Composting technology ranges from relatively
simple windrows to capital-intensive digester drums. This range of technologies exists to
accommodate needs for more process control (in terms of odor control), finished product quality,
and composting speed in order to maximize throughput for a given facility size.
Odors are controlled by a combination of facility enclosure, material handling procedures,
processing technologies, competent process control, and end-of-pipe odor control technologies. The
odor control technologies most often used at mixed waste composting facilities are biofilters.
33 Steuteville, R. 1995. "MSW Composting at the Crossroads." BloCycle. November, pp. 44-46. A followup call was made to contributing author
Nora Goldstein on October 22, 1996, who was able to separate out the source-separated organics facilities from the mixed waste composting
facilities described in the article.
32 U. S. Environmental Protection Agency
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Organic Materials Management Strategies
3.6.3 Technical Problems
Many of the early mixed waste composting facilities were built with no provisions for odor control.
Odor problems have been the primary reason for closing a number of mixed waste composting
facilities. In 1993, there were 16 mixed waste composting facilities in operation. At the end of 1995,
there were only 12.34
Other concerns include the potential health problems caused by airborne fungal spores and
increased truck traffic and noise in residential areas. In the past, composting facilities were easier to
site than other waste handling facilities as they were considered more benign. Siting new facilities,
however, has now become difficult.
Another potential concern with mixed waste composting is the quality of the finished compost.
Chemical contamination, due to the heavy metals and organic chemicals found in batteries,
consumer electronics, household hazardous waste, and other components of the waste stream,
concerns potential end-users. Physical contaminants, such as pieces of glass and plastic, even if not
regulated, can reduce the marketability of the product.
The composting industry is learning from past experience and putting much more time and effort
into effective facility planning and operations, especially with regard to odor control. Technology
has improved, but this has substantially increased the cost of mixed waste composting. Tipping fees
have increased in the past few years. New facilities with state-of-the-art equipment will be
increasingly expensive to build. In most areas of the country, tipping fees at mixed waste
composting facilities are higher than landfill tipping fees.
3.6.4 Applicable Portion of the National Waste Stream Diverted
In theory, this strategy could divert all organic waste currently targeted for composting—
approximately 75 million tons per year.35 All organic materials might never be composted this
way due to the cost and problems with marketing the end-product. Technically, however, this
method of composting is capable of handling 100 percent of the currently discarded organic
materials stream.
3.6.5 Costs Per Ton Diverted
Major cost elements for mixed waste composting facilities include siting, capital expenditures for
equipment and odor control devices, and operating costs. Siting new facilities, especially in nonrural
areas, is becoming increasingly time consuming and expensive as a sophisticated public actively
works against these projects. These costs are very difficult to quantify, as they include a
combination of public sector staff time as well as legal and engineering fees.
35 The estimate of the quantity of materials targeted for composting is based on the 7997 Update. It includes 28 million tons of yard trimmings, 22
34 Nora Goldstein was able to confirm that the four plant closings were all mixed waste facilities.
' The estimate of the quantity of materials targeted for composting is based on tt
millions tons of food waste, and 25 million tons of soiled or unrecyclable paper.
U. S. Environmental Protection Agency 33
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Organic Materials Management Strategies
Mixed waste composting facilities use much higher levels of technology than other organics
diversion strategies in order to sort recyclables and compostables from disposed of waste. Facilities
have dramatically different capital costs depending on the level of technology employed and the
reliance upon low-skilled labor for sorting. Odor control technologies also have associated design,
construction, and operating costs that vary widely from project to project.
Operating costs include labor, operation and maintenance, utilities, and residuals disposal. The
technology used will determine labor requirements. Residuals disposal can be a very large cost item
depending on the compost quality, the corresponding degree of contaminant removal, and the cost
of disposal.
One study reported estimated costs for the capital debt service (presented as Capital Cost Per Ton in
Table 3-9) and operation (presented as Operating Cost Per Ton in Table 3-9) of a number of mixed
waste composting facilities around the country. The estimates do not generally include the costs for
land, as the facilities are all publicly owned and land was already available.36 The resulting average
cost per ton ($49.89) is within the range of tipping fees examined for this report. These tipping fees
are listed in Table 3-9. In addition, it is clear from the data provided in these tables that these
programs are not financially self-sufficient.
In addition to facility costs, mixed waste composting involves collection costs. Unlike other
organics management strategies, however, mixed waste composting does not require a separate
collection system. There is no additional collection cost, therefore, for a community that changes
from hauling its waste to a landfill to hauling its waste to a mixed waste composting facility. For the
sake of comparability with other strategies, a generic collection cost of $63.06 has been developed
from the estimates presented in Table 2-2.37
Costs per ton diverted by this strategy range from a low of $102 to a high of $127. The weighted
average cost of diversion for this strategy is $113 per ton.38
36 It is also excluded to be consistent with the accounting of the other strategies that have sites and that do not include land costs.
37 In Table 2-2, four estimates of collection costs for communities that have no yard trimmings collection were developed; it is reasonable to use
communities with no yard trimmings collection costs as a proxy because communities that haul to mixed waste compost facilities are unlikely to also
collect yard trimmings. The average of the four estimates developed is used here.
38 The average total cost from Table 3-9 plus the estimated collection cost per ton.
34 U. S. Environmental Protection Agency
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Organic Materials Management Strategies
Table 3-9
Mixed Waste Composting Facility Costs
Facility
Sumpter County,
Florida
Wright County,
Minnesota
Truman, Minnesota
(Prairieland Solid
Waste Board)
Columbia County,
Wisconsin
Sevierville,
Tennessee (Sevier
Solid Waste)
Pinetop-Lakeside,
Arizona
WEIGHTED
AVERAGE"
Tons Per
Day
42.50
190.00
70.00
72.00
220.00
15.00
Tons Per
Year3
11,050
49,400
18,200
18,720
57,200
3,900
Capital Cost
Per Ton b
$24.25
$26.32
$41.81
$14.96
$23.60
NAC
Operating
Cost Per Ton b
$39.19
$33.40
$13.13
$28.31
$15.73
$32.05
Total Cost
Per Ton
$63.44
$59.72
$54.95
$43.27
$39.34
NA
$49.89
Public v.
Private
Public
Public
Public
Public
Publicly
Owned,
Privately
Run
Public
Tip Fee
$49.00 f
$55.00 h
$55.00 9
$33.00 h
$35.00 h
$38.00 e
$44.17
Notes:
a Assumes a 5-day work week.
b Assumes full cost accounting.
0 This facility has no debt service because sanitary district funds paid for the project.
d The total cost per ton figure is weighted based on tons per year and does not include the Pinetop-Lakeside facility.
Sources:
Solid Waste Association of North America. 1995. Cosf Information Based on Municipal Solid Waste Composting—A Status Report. Prepared
by Gershman, Brickner & Bratton, Inc. Table VI-4.
TPD information from Steuteville, R. 1995. "MSW Composting at the Crossroads." BioCycle. November, pp. 45-46.
e BioCycle. 1995. February, pp. 48-49.
'BioCycle. 1993. November, pp. 56-64.
g Resource Recycling. 1993. December, pp. 50-51.
h Solid Waste Association of North America. 1995. Municipal Solid Waste Composting—A Status Report. Prepared by Gershman, Brickner &
Bratton, Inc. Table VI-4.
3.7 Residential Source-Separated Composting
3.7.1 Strategy Summary
• Strategy Description. Homeowners separate specified organic materials and set them
out for collection and processing.
• Technical Problems. Programs are relatively new to the United States and have not
been widely tested or researched.
• Applicable Portion of the National Waste Stream Diverted. The residential sector
generates 47.3 million tons of select paper, food scraps, and yard trimmings annually.
• Costs Per Ton Diverted. Since this strategy is not well established in the United
States and only limited operating cost data are available, no cost estimates have been
derived in this report. Limited cost information is, however, provided below based on
pilot results.
U.S. Environmental Protection Agency
35
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Organic Materials Management Strategies
3.7.2 Strategy Description
Increasing sensitivity about the poor quality of mixed waste compost in Europe started a wave of
residential collection programs targeting the organic fraction of solid waste. Several pilot programs
in the Netherlands and Germany in the late 1980s demonstrated that the compost produced with
residential source-separated feedstock contained substantially lower levels of toxic heavy metals
and physical contaminants, such as glass and plastic, than mixed waste compost.
A variety of methods for collecting source-separated organics are used in northern Europe. Many
municipalities that use semiautomated collection for trash issue all households standard size bins or
rolling carts for organics. Other communities have tried dual compartment bins or paper bags.
Collection is generally once per week.
The first U.S. pilot program was in East Hampton, New York, followed by others in Fairfield,
Connecticut, and Santa Barbara, California. The main objectives of these pilot programs were to
determine if residents would comply with additional separation requirements, what type of sort
seemed to yield the best compost quality and diversion results, and what collection systems could be
used.
Several pilot and full-scale residential organics programs are described below:
• Mississauga, Ontario. Four different combinations of sorting and collection were
tried in four zones of the city. These methods included two-stream (i.e., wet and dry)
sorts using bags and three-stream (i.e., recyclables, organics, and trash) sorts using
varying combinations of containers. The report indicated a preference for a three-
stream sort, even if the program cost was determined to be slightly higher, as the
recyclable and compostable materials collected were of higher quality.
• Fillmore County, Minnesota. The source-separated composting facility in this
county is one of the oldest operating plants in the United States (started in 1987).39
Compostables (including food scraps, nonrecyclable paper, and diapers) are collected
weekly. Residents source-separate organics and recyclables from refuse. The facility
is permitted to accept 3,100 tons per year and is operating at close to capacity.40
• Lake of the Woods County, Minnesota. This county has mandatory source
separation of organics. If materials at the curb are not separated they are not collected.
Private haulers bring materials from both commercial and residential sources to the
facility. Incoming loads are screened for contamination. Of the approximately 2,500
tons of material brought to the facility each year, approximately 1,200 tons are
composted.41 The system yields about 500 tons of compost and 500 tons of residuals
per year.42
39 Goldstein, N., R. Steuteville, and M. Farrell. 1996. "MSW Composting in the United States."SzoCycfe November, p.50.
40 Personal communication with Sandra Benson, Fillmore County, Minnesota, October 23, 1996.
41 Personal communication with Gary Lockner, Lake of the Woods County, Minnesota, October 22, 1996.
42 Goldstein, N., and R. Steuteville. 1995. "Solid Waste Composting Plants in a Steady State."5zoCyc/e. February, p. 50.
36 U. S. Environmental Protection Agency
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Organic Materials Management Strategies
• Mackinac Island, Michigan. This community converted its mixed waste composting
facility to a source-separated composting facility in 1993. It maintains organics,
recyclables, and refuse separation programs for both residential and commercial
generators. Organics are placed in biodegradable bags that are collected biweekly for
residents and daily for commercial generators.43
• East Hampton, New York. An organics composting facility in this community
receives material from both residents and commercial entities. Sixty-five percent of
the residents are self-haulers while the rest contract with private haulers. It is not
mandatory for residents to separate organics; however, the town is finding that
participation levels are good.44
• Region of Peel and Town of Caledon, Ontario. These communities began phasing
in a residential source-separated organics collection program in April 1995. The
program began with a pilot project that targeted 4,700 households to participate in
source separation of kitchen, yard, and general household organics. During the
13-week pilot program, participation averaged approximately 50 percent each collection
day. The region is now expanding its capacity and is implementing a full-scale
program.45
• King County, Washington. The county conducted a pilot program with 640
households over a 13-week period in 1995. The program targeted food scraps and
yard trimmings. Participation was voluntary, and residents were provided with
containers. Participation ranged from 59 to 67 percent. About 12 tons of food scraps
were collected from the pilot areas, and the study estimated that up to 21,000 tons of
food scraps could be diverted if all single-family homes were offered the service.46
• DeKalb, Illinois. This community's 14-week pilot project ran two routes with 300
residential participants each. Dual compartment vehicles were used to co-collect wet and
dry materials on one route. Recyclables also were collected in the dual compartment
vehicles on the second route. Eighty-seven percent of the target area residents
participated in the project.47
3.7.3 Technical Problems
As with any new program, it takes time to educate residents. During the initial period of source-
separated organics collection programs, there will be some contamination that has to be dealt with at
the composting facility.
43 Ibid. p. 53.
44 Personal communication with Peter Garnham, Town of East Hampton, October 23, 1996.
45 Gies, G. 1996. "Modular Management of Residential Organics."BioCycle. February, pp. 80-82.
46 King County Department of Natural Resources, Solid Waste Division. 1996. King County Residential Food Waste Collection Pilot Project
Report.
47 Waste Management, Inc., and E&A Environmental Consultants. 1995. Wet/Dry Collection and Composting Project Pilot Study Results.
Prepared for the Illinois Department of Commerce and Community Affairs.
U. S. Environmental Protection Agency 37
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Organic Materials Management Strategies
Residents sometimes complain that their organics containers become more odorous than regular
mixed trash containers. This is more likely to be a problem for households that have a relatively
small portion of nonfood compostables, such as paper, yard trimmings, or cardboard, in the organics
container. This also is especially true for homeowners who have less than weekly collection for the
organics stream. Due to concerns about odor and health, programs that include food scraps should
consider collecting these materials more than once per week, especially in warmer climates.
3.7.4 Applicable Portion of the National Waste Stream Diverted
As shown in Table 3-10, approximately 47.3 million tons of the U.S. residential MSW stream
(e.g., food scraps, yard trimmings, unrecyclable paper, and corrugated) can be targeted by this
strategy.
Table 3-10
Applicable Portion of the Waste Stream Available for Residential
Source-Separated Composting
Materials Targeted by Commercial
Organics Programs
Tissue paper/towels
Paper plates, cups
Other nonpackaging paper
Corrugated boxes0
Milk cartons
Folding cartons
Other paperboard packaging
Bags and sacks
Wrapping papers
Other paper packaging
Food Scraps
Yard Trimmings
TOTAL
% Generated by Commercial
Sources3
60%
20%
50%
10%
50%
60%
50%
90%
90%
70%
50%
90%
Thousands of Tons Generated by
Commercial Sources'3
1,788
190
2,060
730
230
3,234
115
1,782
45
945
10,950
25,200
47,269
Notes:
a Derived from Table C-1 of the 7994 Update.
Material tonnage data from the 7997 Update is applied to percentage generated by commercial sources.
Unrecycled corrugated boxes. According to the Grocery Committee of the Food Marketing Institute (1991), retailers generate 6.6
million tons per year of food scraps and non-recyclable cardboard (soiled, wet, or waxed) at a 3:1 ratio. Therefore, the amount of
soiled corrugated boxes is calculated by dividing the total quantity of food scraps by three.
38
U.S. Environmental Protection Agency
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Organic Materials Management Strategies
3.7.5 Costs Per Ton Diverted
Costs for residential organics programs are not readily available because such programs have not
been widely implemented in the United States.
Average collection costs for the wet and dry collection technologies evaluated in the DeKalb,
Illinois, pilot program ranged from $48 to $62 per ton diverted.4 Wet and dry organics were
collected weekly by a dual collection vehicle. Residents were supplied with cellulose-lined bags,
8-gallon containers to hold the wet waste bag, and 20-gallon wet waste containers to hold full
wet waste bags for curbside collection. On one of the two pilot routes, recyclables were co-
collected with wet and dry organics in blue bags. The cost of the recycling and wet and dry co-
collection was $48 per ton diverted.
Other studies have estimated monthly food scraps collection service fees49 as well as source
separation collection costs in Europe.50
As with source separation collection information, there is a general lack of complete cost
information specific to source separation processing technologies. Swift County, Minnesota, built a
composting facility designed to receive bagged source-separated MSW as feedstock. The cost for
source-separated collection and processing at this facility was compared to the cost of mixed waste
composting in neighboring counties.51 Source-separated costs ranged between $11 and $15 per
month per household, whereas mixed waste composting costs ranged between $10 and $22 per
household per month.52
The $3.5 million composting facility in East Hampton, New York, has a capacity of 40 wet tons per
day. For the first 9 months of 1996, the facility received an average of 18 to 20 tons per day.
Approximately 48 percent of the compostables are received from residents while the rest of the
material was received from commercial sources. Operating costs were not available.53
48 Waste Management, Inc. and E&A Environmental Consultants. 1995. p. 56.
49 See, for example, Table 2 in the King County Residential Food Waste Collection Pilot Project Report. 1996. p.13.
50 See, for example, Scheinberg, A. 1996. "Going Dutch: Collecting Residential Organics in the Netherlands." Resource Recycling. January.
p. 37. This source provides a relatively detailed study of Hie costs of residential collection done in the City of Rotterdam, Holland.
51 Op cit. Spencer.
52 Based on the assumptions of residential solid waste generation of 4.3 pounds per person per day and 2.6 persons per household, source-
separated collection and processing costs range from $65 to $88 per ton. MSW composting ranges from $59 to $129 per ton.
53 Personal communication with Peter Garnham, East Hampton, New York, October 22, 1996.
U. S. Environmental Protection Agency 39
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Organic Materials Management Strategies
4. COMPOST MARKETS AND PRODUCT VALUE
4.1 Review of Benefits Associated With Compost End-Uses
The demand for finished compost helps divert an increasing amount of organic materials from
landfills. In addition, the use and application of finished compost result in a multitude of benefits,
such as enhancing the physical, chemical, and biological properties of soils, which in turn results in
various environmental and economic benefits. A summary of some of the major benefits of
composting is provided below.54
4.1.1 Direct Benefits to Soil
• Improves the Physical Properties of Soils. Compost enhances water holding, soil
aeration, structural stability, resistance to water and wind erosion, root penetration,
and soil temperature stabilization.
• Enhances the Chemical Properties of Soils Compost increases macro- and
micronutrient content, increases availability of mineral substances, ensures pH
stability, and provides a long-term source of nutrient input by acting as a nutrient
reservoir.
• Improves the Biological Properties of Soils. Compost promotes the activity of
beneficial micro-organisms, reduces attack by parasites, promotes faster root
development, and promotes higher yields of agricultural crops.
4.1.2 Indirect Environmental and Economic Benefits
• Since compost has the ability to improve soil water holding capacity and fix nitrogen
into a form that can be used by plants, its use mitigates (at least partially) nonpoint
sources of pollution such as commercial fertilizers.
• By improving soil water holding capacity and reducing water loss as a result of
percolation, evaporation, and runoff, compost application results in water
conservation benefits.
• Compost reduces reliance on pesticides, herbicides, and fungicides by providing an
environment rich in organic matter. Beneficial micro-organisms thrive in this
environment and can outcompete and suppress detrimental pathogens found in soils
where organic matter is low.
• Consistent application of compost reduces soil erosion resulting from wind and water
by improving soil stability.
54 Based on Pratt, W., and W. Shireman. 1994. Agricultural Markets for Compost andMulch: Cost, Benefits, and Policy Recommendations.
California Futures, Sacramento, California. Also based on Rhode Island Solid Waste Management Corporation. 1991. End Use of Leaf and Yard
Waste Compost. Prepared by Tellus Institute. For more information on characteristics and benefits of compost, see Markets for Compost, EPA.
1993.
40 U. S. Environmental Protection Agency
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Organic Materials Management Strategies
4.2 Overview of Compost Markets, Applications, and Constraints
Finished compost can be used in a variety of applications. A report prepared by the Composting
Council identified eight existing market segments for compost, with a potential demand for over
1 billion cubic yards of compost per year.55 This potential demand is substantially greater than the
estimated 48 million cubic yards (37.4 million tons) of finished compost that would be available if
the entire applicable waste stream shown in Table 1-1 were composted.56 Each market segment
identified in the report is described briefly in Table 4-1 along with the potential applications, relative
market size, and potential barriers to widespread use of finished compost by the market segment.
Innovative uses for finished compost are always being explored. The Clean Washington Center in
Seattle, Washington, for example, has experimented with using compost in wetland restoration
applications. The project tested, monitored, and evaluated the use of yard trimmings compost to
restore a wetland that had been significantly damaged by concrete production activities.57
Compost is increasingly being used as a medium for biofilters. These filters are designed to scrub
industrial process air containing odorous and potentially toxic organic chemicals. Biofilters are large
beds, usually constructed in the ground, with pipes that deliver process air placed in a layer of gravel
under covers of compost and soil. The active microbial populations in compost use many organic
compounds in the process air as a food source by breaking them down, reducing their odor, and
rendering them harmless.
Along these lines, Solum Remediation Services, Inc., in Lake Bluff, Illinois, is investigating the
potential for planted compost and contaminated soil mixes to contain or degrade toxic compounds
in soil. Initial field trials indicate that certain pesticides were substantially degraded using this
method.58
Another innovative project, in Washington County, Oregon, entails using yard trimmings compost
as a treatment medium for roadway stormwater runoff. This runoff usually contains various organic
and inorganic pollutants. The compost was used as a substitute for conventional treatment methods
such as detention ponds and grassy swales. Preliminary results indicate that the prototype facility
successfully removed contaminants from the stormwater while occupying less than 10 percent of
the land required by conventional methods.59
Composting Council. 1992. Potential U.S. Applications for Compost. Prepared by Batelle.
56 Volume estimates for the applicable waste stream were calculated assuming 50 percent weight loss due to volatilization in the compost process
and an average bulk density of finished compost of 0.7850 tons per cubic yard.
Clean Washington Center. 1994. Technology Brief: Compost Utilization in Wetland Restoration. Seattle, Washington.
58 Cole, M.A. 1994 Remediation of Pesticide Contaminated Soil with Compost. Symposium on the Biogeochemistry of Compost at Rocky
Mountain Conference on Analytical Chemistry. Denver, Colorado. July 31 to August 5.
59 W&H Pacific. 1993. Compost Storm Water Treatment System. Portland, Oregon.
U. S. Environmental Protection Agency 41
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Organic Materials Management Strategies
Table 4-1
Compost Markets, Applications, and Potential Constraints
Market
Segment
Applications
Potential Market Size
Primary Constraints
Agriculture
Soil conditioning,
fertilizer amendments,
and erosion control for
vegetable and field
crops and forage
grasses.
Development of
marginal lands.
Mulching after
conservation seeding.
Very large, estimated at
895 million cubic yards
per year. Research
indicates that the
demand for compost for
agricultural purposes
within a 50 mile radius
of the 190 largest U.S.
cities would exceed the
supply of compost.
Contaminant
concentrations for crop
production and
cumulative loading limits.
Cost of transportation to
end-user.
Bulk application
equipment requirements
and costs.
Silviculture
Landspreading as soil
conditioner for
evergreen
establishment.
Mulching forwoodlot
soil improvement and
maintenance.
Very large, estimated at
104 million cubic yards
per year. This
segment's potential
demand could exceed
the available supply of
compost.
Transportation cost and
distance.
Bulk application
equipment requirements
and costs.
Sod production
Blending with topsoil to
reduce the amount of
fertilizer needed to
establish sod.
Moderate, estimated at
20 million cubic yards
per year. Market
potential will be dictated
by the rate at which sod
producers deplete
existing topsoil.
Transportation cost.
Bulk application
equipment requirements
and costs.
Residential
retail
Soil amendment to
enrich planting areas.
Top dressing for lawns.
Moderate, estimated at
8 million cubic yards per
year. Much of topsoil
sold in bags is currently
made with compost;
thus, this market has
already been
penetrated.
Postprocess
requirements (e.g.,
screening and bagging)
and associated costs.
Consistent quality
assurance.
Contaminant levels must
be low enough to meet
requirements for
unrestricted distribution.
42
U.S. Environmental Protection Agency
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Organic Materials Management Strategies
Table 4-1
Compost Markets, Applications, and Potential Constraints (Continued)
Market
Segment
Applications
Potential Market Size
Primary Constraints
Nurseries
Potting mixes.
Topsoil amendment for
areas in which field
grown trees are
harvested on a periodic
basis.
Small, estimated at 0.9
million cubic yards per
year.
Consistent pH balance,
nutrient content, particle
size, shrinkage, and
water-holding capacity
required.
Complete and continuous
testing requirements to
ensure high-quality
product and associated
costs.
Compost suppliers will
need to be sensitive and
responsive to specific
growing requirements.
Delivered
topsoil
Blending with marginal
topsoils to produce
topsoils used for
establishing new lawns
and planting trees and
shrubs.
Small, estimated at
3.7 million cubic yards
per year.
Consistent supplies of
compost required to meet
seasonal demands.
Landscapers
Soil amendment for
lawn establishment.
Top dressing.
Mulch.
Small, estimated at
2 million cubic yards per
year.
Quality assurance that
compost does not contain
harmful amounts of
contaminants.
Physical contaminants
that might be visible on
lawns.
Consistent supplies of
compost required to meet
seasonal demands.
Landfill cover
and surface
mine
reclamation
Topsoil amendments for
lower grade and
nonuniform compost
products.
Small, estimated at
0.6 million cubic yards
per year. There are only
a limited number of
landfills or mines that
are undergoing
reclamation at any
given time.
Transportation cost.
Source:
Buhr, McClure, Slivka, and Albrecht. 1993. "Compost Supply and Demand." BioCycle. January.
U.S. Environmental Protection Agency
43
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Organic Materials Management Strategies
Portland, Oregon, sponsored a study to demonstrate compost's effectiveness in controlling
erosion as compared with conventional methods such as sediment fences and wood fiber
hydromulch.60 Fewer sediments were collected from the runoff of the compost-amended plots
than the others. The Federal Highway Administration formerly specified the use of straw to
control erosion on road embankments. It now authorizes the use of compost and mulches as well as
straw. As a followup to the Portland project, EPA will fund a demonstration project to compare the
erosion controlling effectiveness of straw and compost on steep embankments.61
In addition to innovative uses for standard compost products, there has been increasing interest in
'value-added composts,' or composts amended with fertilizers, disease-suppressive micro-
organisms, and other products to stimulate plant growth.62 Specific organisms known to possess
disease-suppressive qualities are cultivated and sprayed onto compost. Disease-suppressive compost
products can be made to order based on customer requirements. O.M. Scott and EarthGro are two
companies marketing lines of fertilizer-amended compost products formulated for specific
applications such as lawn establishment, acid-loving shrub planting, and vegetable planting.
It is clear that many more uses for compost can be discovered with time and attention. As more
organic materials are composted as part of a waste management strategy, the greater the imperative
will be to develop markets with prices sufficient to cover compost production costs.
More information regarding these innovative uses for standard compost products can be found in a
recently published series of EPA fact sheets:
• Innovative Uses of Compost: Bioremediation and Pollution Prevention
(EPA530-F-97-042).
• Innovative Uses of Compost: Erosion Control, Turf Remediation, and Landscaping
(EPA-530-F-97-043).
• Innovative Uses of Compost: Disease Control for Plants and Animals
(EPA530-F-97-044).
• Innovative Uses of Compost: Composting of Soils Contaminated by Explosives
(EPA530-F-97-045).
• Innovative Uses of Compost: Reforestation, Wetlands Restoration, and Habitat
Revitalization (EPA53O-F-97-046).
These fact sheets can be ordered by calling the RCRA Hotline. Callers within the Washington
metropolitan area must dial 703 412-9810 or TDD 703 412-3323 (hearing impaired). Long-distance
callers can call 800 424-9346 or TDD 800 553-7672. The RCRA Hotline operates weekdays 9 a.m.
to 6 p.m., e.s.t.
60 Ettlin, L., and B. Stewart. 1993. "Yard Debris Compost for Erosion Control." BioCycle. December.
61 U.S. EPA. 1997. Innovative Uses of Compost: Erosion Control, Turf Remediation, and Landscaping. p.3.
62 Holusha, J. 1994. Making Compost Double as Pesticide. New York Times. February 27.
44 U. S. Environmental Protection Agency
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Organic Materials Management Strategies
4.3 Compost Product Quality
Compost end-product quality is highly variable depending on the type of organic feedstocks and the
processing method used. Yard trimmings compost can include unscreened oak leaf compost with
low contamination levels but also low nutrient value. On the other hand, screened leaf and grass
compost can have relatively high nutrient content and potentially high levels of soluble salts. MSW
composting, although often considered to produce lower quality products due to the unsorted
feedstocks, has produced composts that meet relatively stringent quality standards.
Table 4-2 presents ranges of several beneficial use parameters for yard trimmings compost, source-
separated compost, and mixed waste compost. For comparison, the table also lists typical beneficial
use parameters of fertilizers, manures, and potting soil. As the table shows, compost has nitrogen,
phosphorus, and potassium concentrations in the same range as manures and potting soils but vastly
different characteristics from fertilizer. Conductivity in Table 4-2 refers to the soluble salts levels of
compost. According to the North Carolina Extension Service, compost's conductivity must measure
less than 10 millimhos per centimeter (mmho/cm) to be rated as unrestricted grade compost.63 All
composts listed in the table meet this standard except the Minnesota samples of mixed waste
compost.
State environmental agencies are increasingly adopting compost product quality standards to protect
public health and the environment. Several categories of compost have emerged such as unlimited
distribution, nonfood chain crop use, and land reclamation. Mixed waste compost, depending on
how it is prepared, might contain concentrations of chemicals that preclude it from being used on
food chain crops or distributed to homeowners for gardening use. Yard trimmings compost has been
found to contain only low levels of pesticide and herbicide, and the concentrations of these
chemicals in no way impacts the potential end-uses for this valuable commodity. There are general
trends of decreasing levels of physical and chemical contamination as a function of the degree of
source separation. Yard trimmings and commercial, institutional, or even residentially collected
source-separated compost is much less likely to exceed state chemical contaminant standards than is
mixed waste compost.64 The value of restricted use products will necessarily be lower than that of
products that have unrestricted use.
In general, compost should be rich in organic matter, be low in soluble salts, meet all regulatory
standards for its end-use, not contain any weed seeds, have no undesirable odor, have a consistent
pH (usually near neutral), and have a moisture content of less than 50 percent.65 The Composting
Council has developed compost product use guidelines for several applications.66 In all cases,
producing compost of consistent quality and composition is important to ensuring that the compost
is marketable.
63 A millimho is one-thousandth of a mho, a measure of conductivity and the inverse of an ohm. Bilderback, T.E., and M.A. Powell. Using
Compost in Landscape Beds and Nursery Substrates. North Carolina Cooperative Extension Service Water Quality & Waste Management.
Publication Number AG 473-14.
64 Richard, T.L., and P.B. Woodbury. 1992. The Impact of Separation on Heavy Metal Contaminants in Municipal Solid Waste Composts.
Biomass and Bioenergy. 3:3-4.
65 Alexander, R. 1994. "The Key to a Successful Composting Program."MSWManagement Elements, p. 42.
66 Composting Council. Compost Parameters and Compost Use Guidelines.
U. S. Environmental Protection Agency 45
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Organic Materials Management Strategies
Table 4-2
Comparison of Compost Beneficial Use Parameters
Compost Type
Yard Trimmings
Compost a
Average
Range
Source-Separated
Organic Compost b
Average
Range
Mixed Waste
Compost
European samples c
Minnesota samples d
Range
Manure e
Dairy cattle
Feeder cattle
Poultry
Swine
Sheep
Horse
Average
Potting Soilf
Range
Fertilizers g
Scotts Vegetable
Garden Fertilizer
Scotts Starter
Fertilizer
Lesco Professional
Starter
Scotts Azalea
Camellia &
Rhododendron Food
Nitrogen
Percent
0.94
0.0002 to 2.1
1.15
0.88 to 1.47
1.11
1.22
0.51 to 1.63
0.50
0.60
1.50
0.65
0.65
0.75
0.86
0.005 to 0.1
17
20
18
15
Phosphorus
Percent
0.30
0.009 to 0.7
0.62
0.38 to 0.8
0.37
0.27
0.15 to 0.69
0.06
0.10
0.31
0.16
0.16
0.10
0.15
0.003 to 0.1
25
27
24
11
Potassium
Percent
0.28
0.17 to 0.37
1.01
0.63 to 1 .37
0.49
0.59
0.14 to 0.91
0.31
0.30
0.29
0.45
0.86
0.55
0.46
0.005 to 0.1
5
5
12
11
PH
7.65
7.1 to 8.2
7.6
7.2 to 7.8
7.66
8
6. 8 to 8.4
MA
MA
MA
MA
NA
MA
NA
NA
NA
NA
NA
NA
Conductivity
mmho/cm
2.99
1.4 to 5.6
3.9
1.9 to 5.6
6.23
14.6
3.2 to 22
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
Notes:
a Sample analyses reported from four yard trimmings composting facilities.
b Average of 150 samples collected in Europe. Results from Vogtmann, H. 1993. Compost Science and Utilization. Autumn, p. 70.
0 Average of 14 samples from European MSW com posting facilities by E&A Environmental Consultants, Inc.
d Average of eight compost products from Minnesota MSW composting facilities. Results from Johnson. 1993. Resource Recycling.
December, p. 52.
e Brady, N.C. 1990. The Nature and Properties of Soils. New York: Macmillan Publishing Company, p. 500.
'Personal communication with Bruce Bargar, Peters Company.
g These values were taken from fertilizer labels at a home and garden store.
46
U.S. Environmental Protection Agency
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Organic Materials Management Strategies
4.4 Fertilizer Substitution
Limited research has been performed to define the fertilizer displacement potential of compost. For
agricultural applications, one study found a 50 percent compost and 50 percent fertilizer
combination resulted in a higher wheat yield than test plots where the entire nitrogen requirement
was supplied by mineral fertilizer.67 Although this research has not been replicated in other
conditions, U.S. Department of Agriculture (USDA) officials suggest a synergistic effect between
the combined use of compost and fertilizer resulting in at least a 15 to 20 percent reduction in
fertilizer requirements.68 A 12-year study at the Connecticut Agricultural Experiment Station
demonstrated that equivalent yields resulted on compost-amended plots when compared to those
with only fertilizer after 4 to 5 years when the steady state of nutrient release is reached.69 It is
important to note that, as shown in Table 4-2, compost does not provide the immediate nutrient
needs of growing crops like mineral fertilizers. Compost releases nutrients more slowly over time.
Research on horticultural compost applications also suggests a reduction in fertilizer requirements.
Although fertilizer applications should be based on the specific soil type, a range of nutrient
requirements for standard agricultural and horticultural plants is well known. Even the low levels of
available nutrients in compost can supply plants with what they need for proper growth when
applied at levels recommended for the soil conditioning properties. Assuming use of a 1 percent
nitrogen product, a 20 percent mineralization rate will supply 4 pounds of available nitrogen per ton
of compost. A 1-inch application, generally recommended for lawn establishment, will supply 3.5
pounds of available nitrogen per 1,000 square feet, well within the standard fertilizer
recommendations of 2 to 6 pounds of nitrogen per 1,000 square feet.70
Once a lawn is established, grasscycling can reduce the use of fertilizers by approximately 33 to 50
percent. A 4-year Rodale Institute study found that a year's worth of grass clippings was equal to
235 pounds per acre of nitrogen (5.4 pounds of nitrogen per 1,000 square feet), 77 pounds per acre
of phosphate, and 210 pounds per acre of potash.71
According to these findings, fertilizer use on lawns could be reduced in certain horticultural and
agricultural applications. The quantities of compost needed to displace the fertilizer depends on the
compost and fertilizer analysis as well as the time horizon for the displacement. Based on available
nitrogen in the first year of application, 12 times as much compost is required assuming a 1 percent
nitrogen compost with a 20 percent mineralization rate in the first year as compared to a 5 percent
mineral fertilizer. Still, the fact that compost continues to release nutrients over time means that less
compost is required in subsequent applications to achieve the same nutrient load. In fact, over a
period of 4 years, less than 8 times the amount of this 1 percent nitrogen compost would be required
to deliver the same nitrogen as a 5 percent mineral fertilizer.72
67 Sikora, L.J., and M.I. Azad. 1993. "Effect of Compost-Fertilizer Combinations on Wheat Yield." Compost Science and Utilization. Spring.
68 Personal communication with Lawrence Sikora, USDA Beltsville, Maryland, Research Center.
69 Maynard, A.A., and D.E. Hill. 1994. "Impact of Compost on Vegetable Yields." BioCycle. March.
70 Tyler, R. 1994. "How Much is Enough?" Lawn and Landscape Maintenance. March.
71 Composting News. May. 1994. pp. 10-11.
72 This calculation assumes a mineralization rate of 20 percent in year one, 10 percent in year two, and 5 percent in years three and four. It also
assumes a requirement of twice the necessary nitrogen load of mineral fertilizer due to leaching. These assumptions are based on personal
communication with Sikora, L., USDA, and from Parnes, R. 1996. Organic and Inorganic Fertilizers. Woods End Agricultural Institute.
U. S. Environmental Protection Agency 47
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Organic Materials Management Strategies
4.5 Potential Market Value of Compost
The market value of compost is influenced by a variety of factors including the demand for soil
organic matter, availability of competing products, compost quality, and the effectiveness of the
producer's marketing strategy. The extent of pre- and postprocessing (e.g., curing, screening,
bagging, and mixing) of compost feedstocks also has a direct effect on the market value of compost.
Compost market value also is affected by the type and quality of organic materials (or feedstocks)
diverted by a given compost program. Source-separated food scrap compost (typically collected in
commercial, institutional, and residential source-separation compost programs) will generally have
high nutrient value and low contamination. Yard trimmings compost will have somewhat lower
nutrient value as well as low contamination. Mixed waste compost will usually have moderate
nutrient value with higher levels of contamination.
Table 4-3 shows reported revenues received from bulk sales of compost end-products. The table
organizes revenue information by type of compost program.73 Yard trimmings composting and
residential source-separated composting operations receive a similar range of revenue per ton of
finished compost. While mixed waste composting products have a lower market value, these
composts (as well as other types of composts produced in municipal facilities) are often used in
the public sector or are given away to home gardeners and farmers. Compost produced by
grasscycling and backyard composting is used by the homeowner. Similarly, onsite institutional
composting facilities often use the compost they produce in their own landscaping operations.
While no money is exchanged in these cases, the end-users are likely to realize economic
benefits in the form of reduced fertilizer and/or soil amendment costs.
73 Revenues are for bulk sales of compost only.
48 U. S. Environmental Protection Agency
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Organic Materials Management Strategies
Table 4-3
Reported Revenues for Various Compost Program End-Products
Feedstocks
Yard Trimmings
Metro Portland Solid Waste Department Facilities,
Oregon a
Atlantic County Utilities Authority, New Jersey b
Rexius Forest Byproducts c
Nature's Choice d
AVERAGE REVENUE PER TON
Source-Separated Orqanics
Intervale Compost Project6
Commercial Composting Company f
Bluestem Solid Waste Agency, Cedar Rapids, Iowa 9
AVERAGE REVENUE PER TON
Mixed MSW h
Pinetop-Lakeside, Arizona
Sumpter County, Florida
Sevier County, Tennessee
AVERAGE REVENUE PER TON
Revenue Per Ton
$45
$25
$30
$27
$32
$53
$50
$15
$39
$4
$6
$1
$3
Notes:
a Personal communication with John Foseid, Metro Solid Waste Department, Portland, Oregon,
November 27, 1996.
b BioCycle. 1996. September, p. 42.
0 "Nurseries, Landscapers and Soil Blenders Are Leading Compost Markets." 1994. BioCycle.
September, p. 44.
d "Nurseries, Landscapers and Soil Blenders Are Leading Compost Markets." 1994. BioCycle.
September, p. 51.
e Personal communication with Adam Sherman, Intervale Compost Project, December 3,1996.
'These costs are proprietary information of the composting company involved. The company
did not wish to be identified.
g BioCycle. 1995. September, p. 44.
h All revenues for mixed waste compost are based on Solid Waste Association of North
America. 1995. Municipal Solid Waste Composting—A Status Report. Prepared by Gershman,
Brickner & Bratton, Inc. Table VI-4.
U.S. Environmental Protection Agency
49
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Organic Materials Management Strategies
5.
SUMMARY AND CONCLUSIONS
Building on the analyses and information in Sections 2, 3, and 4, this section addresses the potential
cost impacts of compost strategies. Strategy costs (i.e., midrange compost strategy costs derived in
Section 3 and shown in Table 5-1) are combined with benefits (i.e., revenues as well as collection
and disposal savings) in order to derive a national 'net cost' per ton diverted and are reported in
Table 5-2. A 'compost strategies savings curve' (Figure 5-1) displays the relative savings of
individual compost strategies (over traditional disposal methods) and the total quantity of organic
materials targeted nationally by each strategy.
Table 5-1
National Summary of Strategy Impacts
Strategy
Grasscycling a
Backyard
composting a
Yard
trimmings
composting
Onsite
institutional
composting
Commercial
composting
Mixed waste
composting
Residential
source-
separated
composting
Materials
Targeted
Residential
and
commercial
grass
Residential
yard
trimmings and
food scraps
Residential
and
commercial
yard
trimmings
Institutional
food scraps,
select paper
grades, and
yard
trimmings
Food scraps
and select
paper grades
All
commercial
and
residential
organic waste
Select
residential
paper grades,
food scraps,
and select
yard
trimmings
Mid range Cost
Per Ton
$1.00
$12.90
$55.00
$49.00
$72.00
$113.00
NA
Cost Per Ton
Range
$0.26
to
$7.04
$5.00
to
$15.68
$21 .65
to
$88.21
$29.00
to
$98.00
$50.00
to
$144.00
$102.00
to
$126.00
NA
Applicable Portion
of the Waste
Stream
(Millions of Tons
Per Year)
14.0
30.6
28.0
2.4
24.6
74.7
47.3
Strategy
Description
Primarily education
and promotion
Education,
promotion, and
possibly bin
distribution
Dedicated
collection and
processing of
leaves, grass, and
brush
Institutions, such
as universities,
correctional
facilities, and
military bases,
collect and
compost organic
materials on site
Dedicated
collection of
targeted materials;
processing off site
Standard garbage
collection;
separation of
compostable waste
at a single facility;
composting of
organic materials
Dedicated
collection of
targeted materials;
processing at a
central facility
Comments
A time-saving
source reduction
strategy for lawn
care
Source reduction
option for those
with space to
compost at home
Well established
strategy
Allows certain
institutions to avoid
high collection and
disposal costs
Viable strategy for
large commercial
generators
Several facilities
have closed due to
technical problems
Limited experience
with this strategy in
the United States
Notes:
a The labor required by citizens is donated at no cost to society.
50
U.S. Environmental Protection Agency
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Organic Materials Management Strategies
To underscore the need to consider individual circumstances, cost ranges per ton diverted by
individual compost strategies also are summarized in this section based on information in Section 3.
This helps to show how individual compost strategy costs vary depending on the type and extent of
technologies implemented.
Report conclusions are provided in the final subsection of the section.
5.1 Midrange Savings of Organic Materials Management Strategies
Table 5-2 provides an estimate of the national savings of individual compost strategies. The table is
divided into five columns. The second column, Midrange Program Costs Per Ton, presents
midrange strategy costs from Section 3 (see Table 3-1 for more details on these costs).
The third column, Collection and Disposal Costs Saved Per Ton, shows the avoided collection and
disposal cost per ton based on information in Section 2. Avoided disposal costs for all programs
assume the weighted average tipping fee of $38 per ton (which reflects all of the requirements of the
October 9, 1991, landfill regulations) as reported in Table 2-1. No avoided garbage collection costs
are assigned to grasscycling and backyard composting programs as it is conservatively assumed that
the incremental diversion effect of these strategies is not large enough to affect garbage collection
costs. An avoided garbage collection cost of $23 per ton is assigned to the commercial composting,
onsite institutional composting, and yard trimmings composting strategies based on avoided
collection costs experienced in well established yard trimmings programs (see Section 2.3). For
mixed waste composting, avoided collection costs are equivalent to garbage collection costs ($64
per ton) since such programs are assumed to obviate the need for garbage collection.
The fourth column in Table 5-2, Revenues Per Input Ton, uses average end-product revenue per ton
from Table 4-3 as a proxy for revenue received for finished compost products. Despite the avoided
fertilizer cost and other benefits of grasscycling and backyard composting (see Section 4), no dollar
value is assigned for end-product revenues for these strategies. Similarly, conservative bulk revenue
values are assigned to all other strategies as reported in Table 4-3. The revenue values in Table 5-2
are reduced by 50 percent in order to take into account losses in the compost process.74 In most
cases, due to decomposition, the composting process reduces the weight of the incoming material by
half. Revenues assumed for all strategies are conservative and, thus, do not reflect the social and/or
environmental value of compost.
The final column in Table 5-2, Savings Per Ton, shows the savings per ton diverted for each
strategy. Costs were calculated by subtracting the total avoided cost per ton and revenue per input
ton from the total program cost per ton. Assuming midrange costs for well established compost
strategies, all of the strategies with the exception of mixed waste composting would result in a net
benefit when the value of avoided collection and disposal and revenues are taken into account.
The savings (over traditional disposal methods) per ton diverted for each strategy shown in Table
5-2 were combined with the applicable size of the waste stream targeted by each strategy to
construct the savings curve shown in Figure 5-1 below. Mixed waste composting is not included in
the curve since it did not result in a savings.
74 As discussed, the 50 percent volatilization is assumed to ensure that revenues are properly allocated to 'diverted tons,' or the total number of
tons that are input into a strategy.
U. S. Environmental Protection Agency 51
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Organic Materials Management Strategies
Table 5-2
Midrange Savings Per Ton Diverted for Compost Strategies
Strategy
Grasscy cling
Onsite institutional
composting
Backyard composting
Yard trimmings
composting
Commercial composting
Mixed waste composting
Midrange Program
Costs Per Ton a
$1
$49
$13
$66
$72
$113
Collection and Disposal
Costs Saved Per Ton
$38 c
$61
$38 c
$61
$61
$102
Revenues Per
Input Ton b
$0
$20
$0
$16
$20
$2
Savings Per Ton
$37
$32
$25
$11
$9
($9)
Notes:
a Midrange program costs are taken from the results derived in Section 3 and rounded to the nearest dollar.
b In most cases, half the material (by weight) that is input into a composting strategy is 'lost' or reduced during processing to evaporation,
insects, and other factors. Thus, these figures reflect the number of tons produced by a composting program, rather than the number of
tons input to that program.
0 To be conservative we assume no savings in collection costs. The tonnage in these composting programs is not reduced significantly
enough to affect the cost of collection.
$35 -
_ $30 •
™ = $25
.- o
> Q
f $20 '
$ 1 5
$ 1 0 -
$5 •
$0
10
Figure 5-1
Savings a Per Ton of Organic Diversion
(Compost Strategies Savings Curve)
:' ^rasscycling
On-Site Institutional Compostinc
ackyard Composting
'Commercial Compostinc
20
30
40 50
Millions of Tons
70
80
90
Notes:
a These savings are from the viewpoint of local government and assume that any additional labor required from citizens is donated
at no cost to society.
bTo be conservative, we assume no savings in collection costs. The tonnage in these composting programs is not reduced
significantly enough to affect the cost of collection.
0 Based on theapplicable portion of the organic waste stream available for composting using existing strategies and
technologies.
52
U.S. Environmental Protection Agency
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Organic Materials Management Strategies
Eighty three percent (62 million tons) of the applicable portion of the national organic waste
stream (75 million tons) could be composted at a net benefit to society through a combination of
grasscycling, backyard composting, onsite institutional composting, yard trimmings composting,
and commercial composting. Grasscycling, onsite institutional composting, and backyard
composting programs could target about 50 percent (37 million tons) of the applicable organic
waste stream at the greatest net benefit to society. Some of the organic materials targeted by
grasscycling and backyard composting programs also could be captured by yard trimmings
composting programs. Commercial composting could capture another 33 percent (24.6 million
tons) of the organic waste stream at a net benefit. Composting the remaining 17 percent (13
million tons) of the organic waste stream could be accomplished through more costly mixed
waste composting or residential source-separated composting strategies.
5.2 Cost Ranges for Organic Materials Management Strategies
The previous section estimated the savings of compost strategies based on midrange cost
estimates. As indicated in Section 3, however, there is a fairly wide range of costs that might be
incurred by a given strategy. Grasscycling programs, for example, that include rebates for
mulching mowers and backyard composting programs that include some form of bin subsidy
require more public outlay than programs that rely only on outreach and education strategies. It
is important to note, however, that less costly options might not be as effective in diverting large
quantities of organic materials from the waste stream. Yard trimmings programs that include
curbside collection, for example, will typically incur higher costs and result in higher diversion
than those that rely on drop-off collection. In some cases, composting costs are determined by
the type of composting technology used. Onsite institutional composting programs that use low-
technology processing options, for example, generally cost less than those that use high-
technology in-vessel options.
5.3 Conclusion
This report reveals several important findings for the future development of composting:
• Approximately 36 percent (75 million tons) of the U.S. MSW stream is available for
composting using existing strategies and technologies.
• Organic source reduction programs, including grasscycling, onsite institutional
composting, and backyard composting, require much less public outlay (when
compared to other composting alternatives) because we assume homeowners' labor is
donated. As a result, operational costs are more than offset by avoided disposal costs.
In combination, these strategies could target about 50 percent (37 million tons) of the
waste stream available for composting.
• About 83 percent (62 million tons) of the applicable organic waste stream could be
targeted by a combination of grasscycling, backyard composting, yard trimmings
composting, onsite institutional composting, and commercial composting programs at
a net benefit.
• Yard trimmings composting programs are the most well established and widespread
compost strategies in the United States. These strategies target about 37 percent (28
million tons of leaves, grass, and brush) of the applicable organic waste stream.
U. S. Environmental Protection Agency 53
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Organic Materials Management Strategies
• Although mixed waste composting facilities can be cost-effective, these facilities
have experienced substantial setbacks in the past few years. Public opposition and
technical difficulties have been troublesome for mixed waste composting facilities in
the United States. As a result, the United States saw a 25 percent decline in the
number of operating mixed waste compost facilities between 1992 and 1995.
• Residential source-separated composting programs have been tried on a limited scale
in several places in the United States. Trends in Europe suggest that source-separated
composting programs might offer a viable alternative for capturing the remaining 17
percent (13 million tons) of organic materials that are not targeted by established
strategies or technologies.
• The potential market for finished compost is much larger than the potentially
available supply. If all applicable materials addressed in this report were captured for
composting, approximately 48 million cubic yards (37.4 million tons) of finished
compost would be created. End-uses for compost in agriculture, silviculture,
residential retail, nurseries' sod production, and landscaping might have a market
potential of over 1 billion cubic yards of finished compost.
• Higher technology does not necessarily yield a more efficient or cost-effective
system. In many cases a low-technology method, such as static pile composting,
might be more cost-effective in terms of compost sales and reduced tipping fees than
a high-technology counterpart such as an in-vessel system. States and municipalities
should use the level of technology that fits their needs.
While this report reflects national average statistics, the basic assumptions are easily translatable
to specific programs. On a basic level, the message of this report is that composting is feasible on
almost every size scale, and it works. The key is choosing the most appropriate strategy. The
more MSW produced, the more organic materials are available for composting. The economies
of scale dictate that the more material available for composting, the lower the cost per ton to
operate whatever composting strategy is used. By their very nature, however, some composting
strategies are more costly to operate than others. The most important part of a successful
composting operation is choosing a strategy or combination of strategies that works for a
particular situation.
54 U. S. Environmental Protection Agency
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