January 19, 2010 | General

Improving Methods Of MSW Measurement

BioCycle January 2010, Vol. 51, No. 1, p. 34
In-depth analysis of MSW management data in California will help fine-tune measurement methods for the 2010 State of Garbage In America survey.
N.J. Themelis and S.M. Kaufman

THERE are two major sources of quantitative data on the generation and disposition of municipal solid waste in the U.S.: the BioCycle/Columbia University State of Garbage in America; and the U.S. Environmental Protection Agency (EPA)/Franklin Associates’ MSW “Facts and Figures” report. These sources differ greatly by millions of tons. A 2008 study, sponsored by USEPA Region 9 and concentrating on the state of California, was published recently in the Journal of the Air and Waste Management Association (AWMA) (Kaufman and Themelis, 2009). It shows how an improved method of MSW measurement can be built upon the foundation provided by the State of Garbage in America (SOG) survey, complemented by an in-depth analysis of state data from various sources within a state.
The EPA “Facts and Figures” reports rely on data provided by Franklin Associates, which uses a form of materials flow analysis (MFA). It is quite difficult to assess the effectiveness of their approach because the specific methodology behind their calculations is not published. A generalized and unpublished description of the original methodology was obtained by the authors. Although the steps taken to calculate MSW flows are not clearly delineated, the underlying Franklin methodology is apparent: Estimates are based on production data for materials and products that end up in the waste stream, and adjustments are made for imports, exports and expected lifetime of materials. The bibliography in the EPA report includes many references to reports by the U.S. Department of Commerce and trade associations, such as the U.S. Steel Recycling Institute, Battery Council International, etc.
Because some of the collected recyclables are used as feedstock for remanufacturing into new materials, it turns out that the Franklin methodology does a good job of tracking the national trends of traditional curbside recyclables (i.e., metal, glass, paper, and plastic. However, it falls short when it comes to organics collection and, more significantly, in its estimate of tonnage of MSW landfilled, which is underestimated by nearly one hundred million tons. Figure 1 shows a comparison between the SOG and EPA results for 2004 data.

In 2003, BioCycle began working with Columbia’s Earth Engineering Center (EEC) to conduct State of Garbage. The BioCycle/EEC State of Garbage in America survey uses an entirely different strategy. Because most states have regulations requiring landfills and waste-to-energy (WTE) facilities to report tons received, it is possible to obtain reasonable data on tonnages landfilled or combusted with energy recovery from the relevant regulatory authorities in each of the 50 states. The same reporting requirements typically aren’t in place for tons of MSW recycled and composted, but the same agencies tend to keep track of these figures as well. In some cases, however, these numbers have not been as reliable as the reported landfilled and WTE tonnages. An example is the state of California that in the past did not report tonnages recycled/composted but an overall recycling/composting rate (e.g. “50%” in the last SOG survey).
To conduct the SOG survey, detailed questionnaires are sent to representatives of the waste management departments of each state. Data provided are thoroughly reviewed by EEC and BioCycle researchers. The main goal of this phase of the survey is to allow for an “apples to apples” comparison of states; that is, to adjust reported values to the EPA standard definition of MSW (residential and commercial waste streams only). State officials are then contacted again to clarify misunderstandings and fill in missing data where possible. This iterative effort results in a report that characterizes WTE and landfilled tons fairly accurately but still leaves some questions regarding the accuracy of recycled/composted tons.

In 2007, EEC received two grants – one from EPA Region 9 (California, Nevada, Hawaii and Arizona) and the other from Aluminum Association, Inc. – to examine the MSW measurement issues in more detail and begin work toward developing a national MSW database. The methodology used in the EPA Region 9 study can be summarized in these basic steps:
• Use SOG methodology and results as the baseline to populate data for the state in question.
• Using EPA Region 9 states, compile and analyze waste data reports published by local and state agencies for the four EPA Region 9 states (California, Hawaii, Nevada and Arizona) to arrive at statewide estimates of waste generation, recycling, WTE and landfilled tonnages. Draw conclusions for further action (e.g., delineate needs for further data research).
• Carry out a materials flow analysis (MFA) for all four Region 9 states using a combination of the direct and indirect methods, consisting of production and other published data. The direct (i.e., physical sampling of wastes, in this case using published results) and the indirect (i.e., estimates of waste generation and disposal from economic, industrial, and other data sources) methods are described in The Practical Handbook (Brunner, 2004). Variations of the methods are widely used in the waste data industry (and also by the EPA).
The first step in cross-referencing MSW data from various states is to eliminate (to the extent possible) apparent inconsistencies arising from different methods of collection and reporting. The easiest way to do this is by using EPA’s MSW definition of residential and commercial MSW streams only (i.e., not counting construction and demolition debris, industrial scrap metals, etc.).
California was used as the starting point for the research because of the high volume of direct and indirect data available for that state, as well as the controversy surrounding its unusual method of collecting and reporting recycling rates. Also, because of California’s size, its recycling tonnage has a large effect on overall national figures. This article only discusses California; data and analysis from the other Region 9 states can be found in the AWMA Journal paper.

The California Integrated Waste Management Board (CIWMB) has published vast quantities of data, but it can be difficult to track the sources of the information. This is particularly the case with recycling tonnages. CIWMB uses a complicated formula in which a base-year waste characterization is applied in combination with disposal tonnages (which are meticulously tracked by CIWMB since its funding has been derived from landfilling fees) to arrive at an estimated recycling tonnage. Generally speaking, disposal tonnages (LF + WTE) are measurement-based while recycling tonnages are estimates. (It should be noted that as of January 1, 2010, CIWMB no longer exists. The Department of Resources Recycling and Recovery, referred to as CalRecycle (, is a new department within the California Natural Resources Agency and administers programs formerly managed by CIWMB and Division of Recycling.
CIWMB reported that 42 million tons of solid wastes were landfilled in the state in 2005. In the previous year, the Board had released a comprehensive report that used detailed sampling procedures at disposal facilities across the state to statistically determine the composition of California’s solid waste (CIWMB, 2004). Using that report and the EPA definitions, it was possible to estimate the non-MSW tons landfilled in the state. WTE tonnages were derived from the BioCycle/EEC 2008 “State of Garbage in America” survey (California reported 2005 data instead of the requested 2006 data) and are also listed in Table 1.
In 2006, Cascadia Consulting Group and R.W. Beck released a CIWMB-funded report characterizing the residuals from materials recovery facilities (MRF) in California (CIWMB, 2006). A total of 390 samples were taken from a representative cross-section of MRFs across the state. Using data reported from these activities, it was possible to back-calculate the recycling tonnages that passed through the MRFs.
Another CIWMB-funded report attempted to quantify the amounts of organic waste being handled by compost and mulch producing facilities in California (CIWMB, 2004, 2nd Assessment). The estimated recycling and organics processing tonnages are shown in the lower half of Table 2.
The methodology used to estimate direct-to-recycler tonnage for paper fiber (i.e., where materials go directly to the mills without processing in a MRF) is as follows: The number of tons of paper recovered in the U.S. in 2005 was 51 million tons. The authors contacted Eileen Berenyi of Governmental Advisory Associates to determine the amount of fiber that went through U.S. MRFs in 2005 and assumed that the difference between total recovered fiber and MRF fiber reported was due to waste paper that went directly to recyclers. We then multiplied this amount by California’s share of U.S. recycling tonnage, according to the BioCycle/Columbia SOG report (20% of U.S.) to arrive at California’s share of U.S. direct-to-recycler fibers of approximately 6.7 million tons.
Putting all of this information together resulted in the estimate of California’s recycling/composting, WTE, and landfilling rates shown in Table 3. Total MSW generation in California in 2005 was 49.9 million tons of which 39 percent was recycled, one percent combusted, and 60 percent landfilled.

The information derived in this study will be utilized to improve the estimates of the source separated recycled and composted tonnages in U.S. MSW in the 2010 BioCycle/EEC State of Garbage in America survey. For example, it is known that the MRFs and paper recyclers have a certain amount of residue disposed in landfills. Therefore, this amount will be subtracted from the national tonnage recycled, so as to avoid double counting. In addition, the next SOG will distinguish between tons recycled and tons composted. Also, attempts will be made to estimate the amounts of yard and food wastes that go to composting or are used as ADC, and the fraction of U.S. MSW that goes to landfills equipped for some landfill gas recovery.
Surveying of states gets underway in February. The final 2010 State of Garbage In America Report will be published in BioCycle this summer.

Scott Kaufman received his Ph.D. in Earth and Environmental Engineering from Columbia University (CU) in 2008. He is U.S. project manager of the Carbon Trust and adjunct assistant professor of Earth and Environmental Engineering at CU. Nickolas Themelis is director of CU’s EEC and Stanley-Thompson Professor Emeritus of the Department of Earth and Environmental Engineering.

Brunner, P.H.; Rechberger, H. Practical Handbook of Material Flow Analysis. Lewis: New York, 2004.
Characterization and Quantification of Residuals from Materials Recovery Facilities; Prepared by Cascadia Consulting Group for California Integrated Waste Management Board: Sacramento, CA, 2006.
Kaufman, S.M.; Themelis, N.J. Using A Direct Method to Characterize and Measure Flows of Municipal Solid Waste in the United States; J. Air & Waste Manage. Assoc. 2009. 59: 1386-1390.
Second Assessment of California’s Compost- and Mulch-Producing Infrastructure, Prepared by Integrated Waste Management Consulting, for California Integrated Waste Management Board: Sacramento, CA, 2004.
Statewide Waste Characterization Study; 340-04-005; California Integrated Waste Management Board: Sacramento, CA 2004.

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