U.S. Case Studies Using Municipal
Solid Waste Decision Support Tool
Susan A. Thorneloe*, Keith A. Weitz**, and Subba R. Nishtala**
*Air Pollution Prevention and Control Division, Office of Research and
Development, U.S. Environmental Protection Agency, Research Triangle Park,
North Carolina
** Center for Environmental Analysis, Research Triangle Institute,
Research Triangle Park, North Carolina
SUMMARY: The recently completed municipal solid waste decision support tool (MSW-DST)
is being used in communities across the United States. The methodology that the tool is based
on incorporates both lilc-cyclc inventory (LCI) analysis and full-cost accounting. The results of
this tool are helping communities to make decisions that will result in more efficient
environmental management. This paper provides an overview of some of the case studies that
the tool has been used for to help illustrate the variety of potential applications.
1. INTRODUCTION
As presented in prior Sardinia conferences, the United States Environmental Protection Agency
(U.S. EPA) has led the development of tools and data collection that can help communities make
more informed decisions regarding municipal solid waste (MSW) management. Often there is
conflicting information or a lack of data that prevents a credible evaluation of options. Through
funding by the U.S. EPA, a MSW decision support tool (MSW-DST) and life-cycle inventory
(LCT) database for North America have been developed. The collection and development of LCI
data, methodology and two software products, were the result of more than 6 years of research
including detailed data collection and software development.
This research was conducted with the cooperation of representatives from state and local
government, solid waste industry, the aluminum, glass, paper, plastic, and steel industries,
environmental interest groups, academia, and others. Over 80 stakeholders were included in this
interactive process which included workshops, working groups, and annual meetings. A
rigorous review of the methodology, data, process models, and software products was conducted
by the stakeholders. In addition, a series of three external program peer reviews were conducted
with internationally recognized experts in life-cycle assessment and solid waste management
(SWM). The final set of reviews, which is still being completed, will include EPA's review
process (i.e., peer, quality assurance, editorial, and administrative reviews). The goal was to
develop a credible, objective, state-of-the-art tool that can be used to make more informed
choices regarding SWM. (Thorneloe ct al., 1999, Barlaz et al., 1999b) Based on the feedback
from reviewers, stakeholders, and ongoing case studies, this has been successfully accomplished.

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The research responsible for the development of the MSW-DST was led by the Research
Triangle Institute (RTI) through a competed cooperative agreement (CR 823052). RTI life-cycle
practitioners and SWM experts formed a research team with other experts from North Carolina
State University, the University of Wisconsin at Madison, Franklin Associates, and Roy F.
Weston, Inc. The extensive work to develop the data and methodology for conducting a LCI
analysis for MSW landfills was conducted through funding provided by the Environmental
Research and Education Foundation (EREF) (Barlaz et al., 1999a). In addition to EPA and
EREF funding, the U.S. Department of Energy provided cofunding which was devoted to data
collection and analysis on electrical energy and MSW composting and combustion (i.e., waste to
energy).
Currently, the MSW-DST is being used in a variety of case studies. A companion paper
provides an overview of one of these case studies that was conducted for the U.S. Conference of
Mayors to evaluate historical trends of greenhouse gas emissions from MSW management. The
subject of this paper is an overview of the other case studies which have already been completed
or are in the process of being conducted. Feedback from the case studies has helped to
determine improvements that are needed in the MSW-DST before it is released to ensure that the
needs of the end users will be met. This paper will identify some of the planned improvements
and considerations when applying the MSW-DST.
2. MSW-DST
2.1 Description of the MSW-DST
The MSW-DST is an interactive tool that enables users to perform cost and environmental
modeling of SWM systems. This may be existing systems, entirely new systems, or some
combination of both based on user-specified data on MSW generation, requirements, etc. The
processes that can be modeled include waste generation, collection, transfer, separation [material
recovery facilities (MRFs) and drop-off facilities], composting, waste combustion (waste to
energy), refuse-derived fuel production, and landfilling. Existing facilities and/or equipment can
be specified in the model so that existing infrastructure and capital expenditures are reflected.
Within each of the process models, there are different options. For example, there are 20
possible collection options, 8 types of transfer stations, 5 MRF designs, and 3 compost facility
designs. The landfill model has tremendous flexibility including three time horizons that can be
used to calculate life-cycle emissions, reflect differences in the management and control of
landfill leachate and gas, as well as providing a means to model bioreactor landfills and ash
landfills. For a case study, we tailor the model to the specific waste management activities and
management practices in each sector of the communi ty.
The MSW-DST can model two residential, two multifamily dwellings, and ten
commercial sectors. The two residential and multifamily dwellings are typically used to
represent urban and rural sectors although the user has the flexibility to use them to represent
differences in waste composition and/or management practices. The 10 commercial sectors may
be broken down by retail, manufacturing, hospitals, restaurants, etc. For each sector, material
flow data are needed, so it is important to have waste-flow data available. Individual waste
components (e.g., food waste, corrugated containers, steel or aluminum cans, high-density
polyethylene, and green glass) can be targeted to help find solutions to minimize cost and
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environmental burdens.
As illustrated in Figure 1, the DST consists of several components including process
models, waste flow equations, an optimization module, and a graphic user interface (GUI).
Spreadsheets were developed using Microsoft Excel for each process model using either default
or user-supplied data to calculate the life-cycle cost and environmental coefficients on a per unit
mass basis for each of the 48 MSW components. For example, in the electric energy
spreadsheet, the user specifies the geographic region of interest which links to the fuel mix of
that region for generating electricity. (The user can also specify a certain fuel mix or use a
national average.) Based on design information and the emission factors for generating
electricity for each fuel type, the spreadsheet calculates coefficients for emissions related to the
use of a kilowatt hour of electricity. These emissions are then assigned to waste stream
components for each facility that uses electricity and through which the mass flows. For
example, MRFs use electricity for conveyors and lighting. The emissions associated with
electricity generation would be assigned to the mass that flowed through that facility. The user
can override default data throughout the tool if more site-specific data are available.
Unmodeled Issues
and
Evaluation Criteria
BEST SWM STRATEGY
DECISION SUPPORT TOOL
OPTIMIZATION
Process Models
Mass Flow
Equations
LCI
DATABASE
FINAL EVALUATION
Cost &
LCI
Coefficients
User Input
Alternative
SWM Strategies
Feasible Waste —
Flow Paths i
User Specified
Restrictions
(e.g., no
¦ waste-to-energy)

Figure 1. Framework for Decision Support Tool
The optimization module is implemented using the 1LOG CPLEX linear programming
solver. The model is constrained by mass flow equations that are based on the quantity and
composition of waste entering each unit process, and that intricately link the different unit
processes in the waste management system (i.e., collection, recycling, treatment, and disposal
options). These mass flow constraints preclude impossible or absurd model solutions. For
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example, these mass flow constraints will exclude the possibility of removing aluminum from
the waste stream via a mixed waste MRF and then sending the recovered aluminum to a landfill.
The user can identify the objective as minimizing total cost or life-cycle parameter [e.g., energy
consumption, greenhouse gases (expressed in carbon equivalents), carbon monoxide, nitrogen
and sulfur oxides, and particulate]. The optimization module determines the optimum solution
consistent with the user-specified objective, mass flow, and constraints (e.g., existing equipment
or facilities, minimum recycling, or landfill diversion rate).
2.2 Data Requirements for MSW-DST
Over 10,000 inputs for the MSW-DST enable the user to track the waste flow throughout the
system. The waste flow is a mass balance of the total tonnage and percent composition of MSW
in each management option (i.e., the total tonnage and percent composition of waste generated,
collected by each collection option, recovered by each type of MRF, and discarded by each type
of disposal activity). Figure 2 presents the system boundaries. Because much of this data would
not be readily available to the user, extensive effort was expended in developing realistic and
credible defaults for each of these parameters. It is very doubtful that a user would include all of
the options that the MSW-DST has available. Often, existing infrastructure, including facilities
and equipment, is reflected (i.e., if a new MRF has been built for processing certain waste
streams, then any future plans will include continued use or even possible expansion of the
MRF).
Tn working with case study participants, the relevant process models are identified, and
the needed site-specific data arc collected. For each sector that is specified (i.e., residential,
multifamily, and commercial sectors), the waste flow is tracked for up to 48 components (e.g.,
corrugated containers, food waste, steel cans, and green glass). These can be aggregated
Energy
Materials
y
y
MSW MANAGEMENT ACTIVITIES
Air
Emissions
Municipal
Solid ->
Waste
Materials^
Recovery/
(CombustiorT)
Landfill J
Com post	y
( Collection )
>- Water
Releases
Solid
Waste
y y y y y
KWh Gas Steam Compost Recyclables
y
y
Materials and
Energy Offsets
Figure2. System Boundaries for MSW-DST
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or left as individual components depending upon the needs of the end user. The default
composition is based on recent L.S statistics that are compiled by EPA's Office of Solid Waste
(U.S. EPA, 1999).
Examples of some of the types of input data that are collected for each case study are:
•	Fuel type in collection vehicles and type of transport
•	Labor costs including overhead rates
•	Market value of recyclables
•	Distance between houses on the collection route
•	Distance between end of route and the transfer station, MRF or treatment/disposal
facilities
•	Time to load vehicle at collection locations
•	Time to unload at transfer station, MRF or treatment/disposal facilities
2.3 Types of Questions for the MSW-DST
The tool was specifically developed to help communities and SWM planners to make more
informed choices regarding SWM (Weitz et al., 2000). The tool can be used to evaluate the
effects of changes in existing MSW management on cost; identify least-cost options to manage
recycling and waste diversion; quantify potential source reduction benefits; quantify carbon
storage associated with MSW biomass; and evaluate options for reducing greenhouse gases,
criteria pollutants, and environmental releases to water bodies or ecosystems. The tool will also
be of value to other user groups including military bases, environmental and solid waste
consultants, life-cycle practitioners, and environmental advocacy organizations in responding to
the following example issues:
•	changes in waste diversion or recycling goals,
•	changes in market value for recovered materials,
•	quantifying potential environmental benefits associated with recycling, and
•	identifying strategies for optimizing energy recovery from MSW.
In addition, the tool is also being used in the Greenhouse Gas Center of EPA's Environmental
Technology Verification Program to help compare new technologies with conventional
technologies in use.
3. CASE STUDIES
Finding solutions that can lead to sustainability has resulted in the need for tools in the U.S. as
well as in other countries. A recently published book, Integrated Solid Waste Management: A
Life-Cycle Inventory, provides an overview of case studies using a life-cycle-based approach
(McDougal et al., 2001). It is well recognized that this type of methodology is needed in order to
provide an equitable comparison of the potential environmental tradeoffs. As a result of requests
from states and local governments, the MSW-DST was developed to help provide information
primarily on a local-community basis. Flowever, as a result of requests for case studies at state
and national levels, the MSW-DST was used to help evaluate the applicability of the tool on a
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wider geographical scale. The community, state, and national case studies arc summarized in the
next sections.
3.1 Community-Based Case Studies
Most of the case studies that are presented here were conducted by RTI and were funded through
the participating communities. Initial case studies were conducted to help in troubleshooting the
tool and testing individual process models. RTI is currently conducting a number of case studies
where they are tailoring the MSW-DST for the specific community and providing training and
technical assistance in the use of the MSW-DST. Options arc being considered, such as the
development of a web-based version of the tool, to provide wider accessibility at a lower cost.
¦	Lucas County, Ohio, was developing a 15-year plan for their SWM system. They were
interested in identifying options that would be more economical and improve environmental
performance. They were able to use the results to increase their recycling rate while actually
realizing a reduction in cost. This also had benefits in reducing life-cycle environmental
burdens. Additional runs are being made to look for further opportunities that will reduce
costs and improve environmental performance.
¦	'llic Great River Regional Waste Authority in Iowa is exploring the efficiency of integrated
collection system versus multiple collection options. Their goal is to evaluate effects of
reconfiguring service areas and applying existing systems to them, and to develop a waste
management plan for a 50% recycling scenario that is to be presented to the state authority.
¦	Anderson County, South Carolina, is evaluating the cost and environmental implications of
implementing a residential curbside recycling program for the more densely populated areas
of the County as well as setting up a yard waste composting program. The MSW-DST was
used to assist in determining least-cost options for implementing a residential curbside
recycling program while simultaneously considering environmental performance including
potential benefits from increased recycling rates.
¦	The State of Georgia is interested in evaluating the effects of a ban on landfilling yard waste
in Gwinnet County which is a suburb of Atlanta. Because of the existing air quality
concerns, increased emission of nitrogen oxides (NOx) and other pollutants that aggravate
urban smog, are of concern. Current NOx emissions attributable to yard waste collection are
estimated to be 105 tons per year, and the implementation of a yard waste ban would result in
an 11% increase in NOx. This increase results from an increase in the number of trucks
(from 171 to 201) needed for separate mixed waste and yard waste collection, as opposed to
commingled collection.
¦	The State of Wisconsin is investigating the environmental benefits of statewide recycling
programs. The MSW-DST was used to analyze how changes in levels of state-mandated
recycling goals can potentially affect environmental aspects of recycling for a local
community. Case studies were conducted for Madison and Milwaukee to assist the State in
deciding what solid waste strategies should be used in the future to meet environmental
improvement goals.
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¦ Case studies are being conducted for the U.S Navy in the Pacific Northwest. There is major
interest to reduce cost, increase recycling rates, and ensure that environmental goals arc
being met. In addition, with the closing of smaller local landfills and transporting waste by
rail to £ larger regional site, the Navy is interested in evaluating the change in cost, energy
consumption, and environmental releases. The Navy is also evaluating options that would
combine waste from nearby communities to identify more cost effective and environmentally
preferable solutions to a more regional approach for integrated waste management. The case
study is to be conducted to help with the implementation of a SWM plan. The Navy is also
considering additional case studies in San Diego and the Pacific Rim.
3.2	State-Based Case Studies
The MSW-DST has been used to provide information to the States of Georgia, Minnesota,
Washington, and Wisconsin. The State of Wisconsin was interested in being able to quantify the
environmental benefits of statewide recycling programs. The MSW-DST was used to analyze
how changes in levels of state-mandated recycling goals can potentially affect environmental
aspects of recycling. The results of this study are being used to assist the State in deciding what
solid waste strategies should be used in the future to meet environmental improvement goals.
The States of Washington and Minnesota were also interested in being able to quantify the
tradeoffs between options being considered. This has been primarily the result of issues raised
about the cost of existing recycling programs. Before the MSW-DST was available, these kind
of comparisons did not reflect the full costs of the system and consider only the landfill tipping
fee which doesn't necessarily reflect the total cost of lining, operating, monitoring, leachate and
gas treatment, etc. Also, many of the past comparisons did not consider potential benefits of
recycling through conservation of resources. The MSW-DST provides states with a tool that
provides an objective, credible, and life-cycle-based evaluation that is helpful in decision
making.
In the spring of 2000, a workshop was conducted in Toronto, Canada, to help
stakeholders identify opportunities for reduction of persistent bioaccumulative toxics (PBTs)
including mercury and dioxin/furans. Solid waste management had been identified as one of the
major contributors of PBTs to the Great Lakes. EPA's Great Lakes National Program Office
(GLNPO) requested assistance in quantifying the PBTs associated with MSW management. The
MSW-DST was used for providing results at the workshop and helping to provide perspective on
the level of PBTs associated with MSW management versus other sources. MSW combustion,
or waste-to-energy, had been one of the larger sources of dioxin/furans in the U.S. As a result of
Clean Air Act regulations and use of improved air control technology, this source is now one of
the lowest sources of dioxin/furans. Use of the MSW-DST helped provide workshop
participants with up-to-date data and information to understand the relative contribution of PBTs
from different sources. This helps to identify more cost-effective policies for reducing PBTs and
reducing the current levels in the Great Lakes.
3.3	Natioual-Based Case Studies
A model for a national-based systems engineering approach was the subject of a recent doctoral
candidate (S oderman, 2000). This thesis demonstrated how resources and costs can be made
more efficient through evaluation of SWM on a national scale. Although simplifying
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assumptions must be made, models can be run with the help of sensitivity analysis lo provide
credible results to decision makers. Currently, this type of information is not available and often
policy-makers don't understand the potential costs and environmental impacts resulting from
SWM.
The case study that was conducted using the MSW-DST on a national basis is the subject
of a companion paper (Thorneloe et al., 2001). Participants in the study were primarily
interested in evaluating historical trends of greenhouse gases associated with MSW management.
Data from the 1970s were compared to recent data. The results indicated that, although the
amount of MSW has almost doubled since the 1970s, the level of greenhouse gases has
decreased by a factor of 4. The study was conducted for the U.S. Conference of Mayors through
funding by the Integrated Waste Services Association. This information was helpful in
understanding that programs that have been adopted have led to significant reductions of
greenhouse gases. Many of the mayors were interested in the use of the MSW-DST for their
communities to (1) help quantify the benefits resulting from improvements that have been made
over time, and (2) identify further opportunities for improvement.
ACKNOWLEDGEMENTS
The authors wish to thank the participants in the case studies presented in this paper and the
various stakeholders and reviewers who provided valuable feedback in the development of the
MSW-DST. For further information about availability of the MSW-DST, LCI database, project
documentation, refer to the project website (RTI, 2000).
REFERENCES
Barlaz M.A., Camobreco V., Repa E., Ham R.K., Felker M., Rousseau C, Rathle J., (1999a)
Life-Cycle Inventoryof a Modem Municipal Solid Waste Landfill, Sardinia 99, Seventh
International Waste Management and Landfill Symposium, Published in Proceedings, Volume
m, Pages 337-344, October 4-8, 1999.
Barlaz M.A., Ranjithan S.R., Brill E.D. Jr., Dumas R.D., Harrison K.W., Solano E., (1999b)
Development of Alternative Solid Waste Management Options: A Mathematical Modeling
Approach, Sardinia 99, Seventh International Waste Management and Landfill
Symposium, Published in Proceedings, Volume I, Pages 25-32, October 4-8, 1999.
McDougal F., White P., Franke M., Ilindle P., Integrated Solid Waste Management: A Life-
Cycle Inventory, Second Edition, 2001.
Research Triangle Institute. Pollution Prevention. Life Cycle Assessment. Life Cycle
Management of Municipal Solid Waste. http://www.rti.Org/unit5/ese/n2/lca.cfm#life
(accessed September 2000).
S oderman M.L., A Systems Engineering Approach to National Waste Management,
Thesis for the Degree of Doctor of Philosophy, Department of Energy Conversion, Chalmers
University of Technology, Gothenburg, Sweden, 2000.
Thorneloe S.A., Weitz K., Barlaz M., Ham R.K., (1999) Tools for Determining Sustainable
Waste Management Through Application of Life-Cycle Assessment: Update on U.S.
Research, Sardinia 99, Seventh International Waste Management and Landfill Symposium,
Published in Proceedings, Volume V, Pages 629-636, October 4-8, 1999.
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Thorneloe S. A., Weitz K., Nishtala S., and Zannes M., (2001) Life-Cycle Evaluation of
Greenhouse Gas Emissions from Municipal Solid Waste Management in the United States,
Sardinia 01, Eighth International Waste Management and Landfill Symposium, To be
Published in the Proceedings.
U.S. Environmental Protection Agency. Characterization of Municipal Solid Waste in the United
States: 1998 Update; EPA 530-R-99-021; Office of Solid Waste and Emergency Response:
Washington, DC, July 1999, http://www.epa.gov/epaoswer/non-hw/muncpl/msw98.htiri.
Weitz K., Nishtala S., Thorneloe S., Towards Sustainable Waste Management Using a Life-
Cycle Management Decision Support Tool, WASTECON 2000, Published in
Proceedings, Cincinnati, Ohio, October 23-26, 2000.

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TECHNICAL REPORT DATA
N RM RI-- RTP~ P~ 617 (Phase read Instructions on the reverse before comple
1. REPORT NO 2
EPA/600/A-01/114
3 REC
St Mil 1 IMIIBIIIII llllllltt || lit
A TITLE AND SUBTITLE
U.S. Case Studies Using Municipal Solid Waste
Decision Support Tool
5. REPORT DATE
6. PERFORMING ORGANISATION CODE
7. AUTHORS
S.A. Thorneloe (EPA). and K.i\. Weitz and
S. R. Nishtala (RTl)
t PERFORMING ORGANIZATION REPORT NO.
9. PfcRFORMING ORGANIZATION NAME AND ADDRESS
Research Triangle Institute
P.O. Box 12194
Research Triangle Park, North Carolina 27709
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
NA
12. SPONSORING AGENCY NAME AND ADDRESS
U. S. EPA, Office of Research and Development
Air Pollution Prevention and Control Division
Research Triangle Park, North Carolina 27711
13 TYPE OF REPORT AND PERIOD COVERED
Published paper; 5/00-5/01
14. SPONSORING AGENCY CODE
EPA/600/13
is supplementary notes APPCD project officer is Susan A. Thorneloe, Mail Drop 63, 919/
541-2709. For presentation at 8th Waste Management and Landfill Conference, Cag-
liari, Italy, 10/1-5/01.
i6.abstract jhe paper provides an overview of some case studies using the recently
completed municipal solid waste decision support tool (MSW-DST) in communities
across the U.S. The purpose of the overview is to help illustrate the variety of
potential applications of the tool. The methodology that the MSW-DST is based on in-
corporates both life-cycle inventory analysis and full-cost accounting. The results
of this tool are helping communities to make decisions that will result in more effi-
cient environmental management.
17. KEY WORDS AND DOCUMENT ANALYSIS
a DESCRIPTORS
b. IDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Pollution Life (Durability)
W astes
Management
Decision Making
Inventories
A ccounting
Pollution Control
Stationary Sources
Municipal Solid Waste
Decision Support Tools
13B
14G
05A
05J
15E
18 DISTRIBUTION STATEMENT
19 SECURITY Cl-ASS (This Report)
21. NO. OF PAGES
20. SECURITY CLASS (This Page)
22. PRICE
EPA Form 2220-1 (Rev. 4-77 ) PREVIOUS EDITION IS OBSOLETE	rorms/admin/techrplfnn 7/8/9S pad

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