Local governments have the primary responsibility for the collection, treatment, and disposal of MSW. Efficient use of manpower, equipment, materials, and energy is one of the keys to building a sustainable MSW management system. Another key is making the system economically feasible over the long term.

By Keith A. Weitz, Subba Nishtala, and Susan A. Thorneloe

Decision-Support Tool
Testing of the Tool in Community-Based Case Studies
Project Information

In developing sustainable strategies for MSW management, communities seek approaches that are economically viable, benefit the environment, and improve the quality of life. Although communities have had access to reliable cost information related to their MSW management systems, they have lacked comparable environmental information with which to assess the environmental benefits and burdens of alternative MSW management options. Many communities and solid waste planners are often faced with limited and unorganized information on which to base decisions regarding integrated MSW management strategies.

The United States Environmental Protection Agency’s Office of Research and Development is working with the Research Triangle Institute (RTI) and its partners to develop a computer-based decision-support tool (DST) designed to evaluate the cost and environmental performance of integrated MSW management systems. By adopting strategies that improve the integration and efficiency of MSW management operations, local governments can reduce the release of greenhouse gases, conserve energy and other natural resources, minimize impacts to local air and water quality or ecosystems, and improve the quality of life in their communities.

In addition to the DST, this research is producing a stand-alone database that enables users to search for data specific to a waste management system unit operation, structure, piece of equipment, or life cycle inventory (LCI) parameter (i.e., air emission, waterborne effluent, and solid waste). The information and tools developed through this effort will enable the evaluation of the tradeoffs among environmental burdens, energy, and costs for different integrated MSW management strategies including collection, separation, transportation, material recovery facilities (MRFs), remanufacturing, composting, combustion, and landfilling.

Decision-Support Tool

The DST is a screening-level program designed to aid in evaluating the cost and environmental burdens of integrated MSW management strategies. It enables users to simulate existing strategies and conduct analyses of new scenarios to optimize the cost or environmental performance of the system. The tool is designed to be used in conjunction with such community-specific data as waste generation and composition, recycling or diversion programs, and facility (e.g., landfill) design and operation.

The processes that can be modeled include multiple alternatives for waste collection, transfer stations, MRFs, mixed municipal and yardwaste composting, combustion, refuse-derived-fuel combustion, and disposal in a traditional, bioreactor, or ash landfill. Existing facilities and equipment can be incorporated as constraints to ensure that previous capital expenditures are not negated. A screen capture of summary-level results is shown in Figure 1.

Figure 1. Solution Summary

The user can view the suggested cost and environmental data for a waste management strategy as well as scan process-level data on the full costs and life cycle environmental burdens. Note: The number of significant digits shown in the DST results is currently being adjusted. The final version will display two to three significant digits.

In addition to viewing summary-level results, users can click down to obtain more detail about each waste management operation selected. Data on all environmental burdens that include multipollutants and media are available on a total or process-level basis. This information can be used to help evaluate the tradeoffs of different strategies and assess environmental performance. In addition, the full costs associated with the management of integrated waste management systems are also provided for the total strategy or on a process-level basis.

Communities and solid waste planners can use the tool, for example, to evaluate the effects of changes in the existing MSW management on cost; identify least-cost ways to manage recycling and waste diversion; and evaluate options for reducing greenhouse gases, criteria pollutants, and environmental burdens to water quality or ecosystems. The program will also be valuable to other user groups, including military bases, environmental and solid waste consultants, industry, 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,
• identifying strategies for optimizing energy recovery from MSW.

Through ongoing case studies, the DST’s potential applications will be evaluated to help clearly understand its potential uses and limitations. The DST contains general engineering cost parameters and therefore is not intended for setting prices for any specific waste management service. The cost results provided represent screening-level engineering costs that accrue to the public entity (e.g., local government). A more detailed cash-flow analysis substituting local parameters would be needed to determine the appropriate prices for services and materials. The tool is also not designed to conduct life cycle comparisons of any specific products or materials. It is considered to be a comprehensive agent in finding improved solutions for sustainable waste management.

Testing of the Tool in Community-Based Case Studies

A prototype of the DST is being tested in a number of case-study applications. Case studies are ongoing with Lucas County, OH; the Great River Regional Waste Authority, IA; Anderson County, SC; the State of Wisconsin; the Integrated Waste Services Association; and the US Navy. Although the tool was originally designed with local communities in mind, we are testing it in applications at the state and national levels as well. Examples of the types of issues being analyzed for different groups and studies are described in the following paragraphs.

Lucas County, OH, is currently developing a 15-year plan for its solid waste management system. It feels its current waste operations are not cost-effective and ignore pollution and life cycle implications. The analyses and results of this case study are helping in the development of integrated, cost-effective, and environmentally preferable plans and are targeting opportunities for increasing recycling rates, reducing costs, and improving environmental performance.

The Great River Regional Waste Authority in Iowa is exploring the efficiency of an integrated collection system versus multiple-collection options. Its 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 to be presented to the state authority.

Anderson County, SC, is evaluating the cost and environmental implications of establishing a residential curbside recycling program for the more densely populated areas of the county and of setting up a yardwaste composting program. The results of this study will assist the county in determining the most cost-effective strategies for implementing the programs while simultaneously considering environmental performance.

The State of Georgia used the tool to analyze the effects of a yardwaste ban on air emissions for Gwinnett County. Current nitrogen oxide (NO_x) emissions attributable to yardwaste collection are estimated to be 105 tpy, and the elimination of a yardwaste ban would result in an 11% decrease in NO_x. The number of trucks needed for collecting commingled yardwaste with MSW increases from 171 (with no yardwaste collected with MSW) to 201. Discussions are underway to conduct additional case studies in Georgia to evaluate regional solutions to integrated waste management.

The State of Wisconsin is investigating the environmental benefits of statewide recycling programs. We are using the tool to analyze how changes in state-mandated recycling goals can potentially affect environmental burdens. We are also analyzing how landfill-tip-fee surcharges can affect the role of recycling. The results of this study will assist the state in deciding what solid waste strategies should be used in the future to meet environmental improvement goals.

The Integrated Waste Services Association is interested in analyzing the effect that advancements in MSW management technologies have on greenhouse gas emissions. We are using the DST to investigate the greenhouse gas emissions from various technologies including landfill gas recovery, waste-to-energy combustion, and recycling.

The US Navy has requested a case study for the Navy Region Northwest. There is major interest in reducing cost, increasing recycling rates, and ensuring that environmental goals are being met. In addition, with the closing of smaller local landfills and the transport of waste by rail to a larger regional site, the navy is interested in evaluating the change in environmental burdens, energy, and economics. The navy is also evaluating options that would combine waste from nearby communities in order 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 by the fall of 2000 and will result in implementation of a solid waste management plan. The navy is also considering additional case studies in San Diego and the Pacific Rim.

These case studies are providing cost and environmental information about alternative waste management strategies to these groups to assist in the development of management plans and policies. The case studies also are enabling the research team to refine the methods and data used in the DST as well as the user interface.

Additional case studies are planned and will reflect the issues of urban and rural settings throughout the US to ensure that the DST system is flexible enough to handle the wide range of variation among local communities.

Project Information

When completed, the DST and LCI database will be publicly available. An agreement is being developed to determine how the outputs will be formally released. EPA is planning to develop a Cooperative Research and Development Agreement with the commercial partner(s) that will address future updates, maintenance, technical support, and other issues associated with the release and application of the DST and LCI database.

Major emphasis will be on ensuring wide access by keeping the cost of the DST to a minimum. The fees will help cover the costs associated with future updates, maintenance, and technical support that stakeholders have stated are essential in ensuring the success of this tool.

Those who are interested in the application, such as local and state governments, might want to obtain a copy for use in-house or to contract the services of consultants. The program and supporting documentation have been developed so that solid waste management professionals can use the tool for a wide range of applications. A user’s manual and other extensive documentation will be available in addition to documentation of the case studies conducted to date. The details of how the final outputs will be released will be determined over the next several months with emphasis on the needs and interests of the stakeholders.

General project information and interim draft documentation are being finalized. Final reports include user’s manuals for both the LCI database and the DST and a project overview report with detailed documentation of process models, data, and methodology. Final reports and documentation are scheduled for release this summer. Information can be found on the project’s Internet site (www.rti.org/units/ese/p2/lca.cfm#life), including a PowerPoint presentation of the DST. The research team is also preparing a series of peer-reviewed journal articles to highlight the different aspects and uses of this tool and to summarize findings from case studies in different communities where this life cycle tool has been applied.

For further information, contact EPA’s senior project officer, Susan Thorneloe, at 919/541-2709 or Thorneloe.Susan@epa.gov.

Keith A. Weitz and Subba Nishtala are with the Research Triangle Institute in Research Triangle Park, NC, and Susan A. Thorneloe is with EPA’s Office of Research and Development, Air Pollution Prevention and Control Division in Research Triangle Park, NC.

MSW
Elements 2001