Project Summary and Results

Minnesota is a national leader in the responsible management of municipal solid waste (MSW). But even with a recycling rate of 46%, the state discarded nearly 3 million tons of MSW in 1998. This waste composition study is part of a continuing effort to measure and understand the waste generated in Minnesota.

The state has extensive data collected on the quantities of waste discarded and recycled in Minnesota since 1989. The waste sort data focus on what is in that 3 million tons of waste, and help identify what kinds of waste are generated.

This 1999 waste sort builds on the efforts of a sort conducted in Minnesota in 1990-1992, providing an opportunity to compare the changes in Minnesota's waste in the last decade.

The Solid Waste Management Coordinating Board (SWMCB), the Minnesota Pollution Control Agency (MPCA) and the Office of Environmental Assistance (OEA) wanted to develop a representative, statistically defensible estimate of the composition of Minnesota's municipal solid waste (MSW) stream. They hired R. W. Beck, Inc. and GRG Analysis to conduct the study.

The statewide MSW composition study is based on field sorting events around Minnesota between September 27 and November 20, 1999. The data are compiled from 390 samples — nearly 95,000 pounds of MSW.

Study Objectives

• Establish a baseline for measuring future success in achieving waste management objectives;
• Assist the partners in setting future policy direction and management priorities; and
• Assess progress in reduction and recycling since the 1991/1992 MPCA study.

Participating Facilities in the Study

Waste for the study was collected at eight facilities around Minnesota. The goal was to collect waste that was representative of the discards around the state. The selected facilities included two municipal solid waste landfills, two transfer stations, two waste-to-energy (WTE) facilities, one MSW composting facility, and one refuse-derived fuel (RDF) production facility. The state was divided into two regions:

• Metropolitan Region, which includes the six member counties of the Solid Waste Management Coordinating Board — Ramsey, Washington, Anoka, Hennepin, Dakota and Carver. These five facilities manage about 72% of the region's solid waste. Based on 1998 numbers, the Metropolitan region produced 1.84 million tons of MSW — 61% of the state's total.
  • Brooklyn Park Transfer Station (Brooklyn Park, Minn.)
  • Burnsville MSW Landfill (Burnsville, Minn.)
  • HERC Waste-to-Energy (WTE) (Minneapolis, Minn.)
  • NRG Newport Refuse-Derived Fuel Production Facility (Newport, Minn.)
  • Waste Management/United Waste Transfer Station (St. Paul, Minn.)
• Greater Minnesota includes counties in Minnesota that are not members of the Solid Waste Management Coordinating Board. These three facilities manage about 9% of all the waste collected in Greater Minnesota. Based on 1998 numbers, the Greater Minnesota region produced 1.16 million tons of MSW — 39% of the state's total.
  • Polk County Waste-to-Energy (WTE) (Fosston, Minn.)
  • Prairieland MSW Composting Facility (Truman, Minn.)
  • St. Louis County MSW Landfill (Virginia, Minn.)

How Materials Were Sorted in the Study

What is "Municipal Solid Waste (MSW)"?

The Minnesota Waste Management Act (Minn. Stat. § 115A) defines municipal solid waste as follows:

Subd. 21. Mixed municipal solid waste.
(a) "Mixed municipal solid waste" means garbage, refuse, and other solid waste from residential, commercial, industrial, and community activities that the generator of the waste aggregates for collection, except as provided in paragraph (b).
(b) Mixed municipal solid waste does not include auto hulks, street sweepings, ash, construction debris, mining waste, sludges, tree and agricultural wastes, tires, lead acid batteries, motor and vehicle fluids and filters, and other materials collected, processed, and disposed of as separate waste streams, but does include source-separated compostable materials.

What materials were included?

The waste samples were sorted into 8 broad categories of materials. Including sub-categories, there were 59 categories in all.

• Paper. The selected paper subcategories were consistent with present specifications for most recycling programs in Minnesota. Newsprint, high grade, and magazines were each included as separate subcategories and, in addition, the subcategories of boxboard and mixed recyclable paper were added. The old corrugated containers (OCC) were subdivided into "uncoated - recyclable," "uncoated - nonrecyclable," and "coated OCC" to further analyze the types of OCC being disposed. A "catch-all" category for nonrecyclable mixed paper was also included.
• Plastic. For both polyethylene terephthalate (PET) and high density polyethylene (HDPE), distinguishing uncolored from colored grades was necessary to be consistent with the sensitivity of these plastic resins to existing recycling markets. Thus, PET was subdivided into "bottles/jars - clear," "bottles/jars - colored" and "other PET." HDPE was subdivided into "HDPE - natural" and "HDPE - colored." Film plastics were subdivided into two subcategories - "film-transport packaging" and "other film" - to distinguish pallet wrap from other film.
• Metals. The selection of the subcategories for this primary category was relatively straightforward. Aluminum and ferrous were each subdivided into "containers" and "non-containers" with an additional separate category for "other non-ferrous."
• Glass. This primary category is divided into "containers" and "non-containers." Because of the varying markets for colored glass containers, this category was divided into clear, brown and green glass.
• Organic Materials. Yard waste was divided into "woody material" and "grass and leaves" because of different material handling and processing needs. Wood was subdivided into wood pallets, treated wood and untreated wood. Wood pallets are generally perceived as materials with primarily a commercial origin that compose a measurable portion of the organic materials in the MSW stream. Recovery of wood is generally limited to untreated materials because of toxicity concerns in the treated wood.
• Problem Materials. The selection of problem materials subcategories hinges on identifiable materials that are likely sources of trace metals such as lead, cadmium and mercury, yet may provide potential materials recovery opportunities. As a result, batteries were selected as a subcategory. Televisions and computers were identified as separate subcategories. These products were included as separate subcategories from "electric and electronic products" because of their potential recovery opportunities and toxicity concerns. Computers were subdivided into the additional subcategories of monitors and non-monitors because of the different handling and recovery requirements associated with each of these components.
• Household Hazardous Waste/Hazardous Waste (HHW/HW). With HHW/HW, the challenge was to identify a range of subcategories that is comprehensive in reflecting the various types of HHW/HW but consistent with specific programs. Second, the issue of empty vs. non-empty containers also raises both safety and material categorization issues. To distinguish "empty" from "non-empty" HHW/HW, subcategories included only containers with product. A separate category for empty HHW/HW containers was created, but was included in the primary category of "Other Waste." The HHW/HW category distinguishes between latex and oil paints, as well as automotive used oil/filters and other automotive products such as anti-freeze. A "catch- all" subcategory for other HHW/HW was also included. A total of eight HHW/HW subcategories were selected.
• Other Waste. A miscellaneous set of subcategories that include more prominent items such as textiles, carpet, rubber, and sharps and infectious wastes. In addition, separate subcategories for construction and demolition debris (excluding wood) and household bulky items (furniture and mattresses) were included. As previously mentioned, this primary material category includes a subcategory for empty HHW/HW containers. A "catch-all" subcategory termed "miscellaneous" was also included.

What was excluded from the study?

Because the study focused on MSW, the sampling protocol attempted to exclude loads that could be clearly identified as composed of non-MSW, such as construction and demolition (C&D) wastes, special wastes (i.e. ash, grit, etc.) or other industrial processed wastes. All selected loads were assumed to be MSW unless they appeared to contain exclusively non-MSW. A few loads were excluded from the study, including some which contained exclusively C&D wastes.

Read Section 3-Study Design for more details.

Statewide waste sort results

The statewide figures are based on 380 samples from the 8 facilities — over 90,000 pounds of MSW. Here is the breakdown of materials in Minnesota's garbage. These figures include waste from both residential and industrial/commercial/institutional (ICI) sources.

See Section 4-Study Results for much greater detail.

Waste generation: Residential vs. Non-residential

The study design and sampling methods were intended to identify how much of the state's waste comes from the residential sector (including both single-family and multi-family residences) compared to the industrial/commercial/institutional (ICI) sector.

Breakdown by sector

Sampled loads were classified as residential, ICI, or mixed waste. In addition to a visual inspection, the team interviewed the driver to discern loads that should be classified as residential as opposed to ICI. "Mixed waste" included waste from both the residential and ICI sectors.

These results are based on the sorts in the Metropolitan Region, where enough loads could be identified by their source. The results are consistent with the idea that the industrial/commercial/ institutional (ICI) sector recycles more of its wastes.

Significance

Understanding the proportion of residential to ICI waste is important as Minnesota plans for future management of solid waste in the state.

• Better targeting of recycling efforts. The growth of Minnesota's recycling rate has slowed in recent years. Planners and recycling coordinators in the state can use the waste sort data to see which recyclable materials are going into the trash instead of into local recycling programs. Educational efforts can be focused on improving the collection of materials, and planning can be directed towards materials that are found in MSW in large quantities.
• Improving the per capita calculations for waste generation. How much waste does the typical Minnesotan produce each year? The easiest way to answer is to divide the total waste generation by the state's population, but that includes waste from businesses. This waste sort gives planners a better idea of the quantities and types of wastes consumers are throwing away.

See Section 5 for more details.

Program Implications

One of the primary objectives of the study was to establish a baseline for measuring the impacts of future program activities. The results of the study are to be used in conjunction with the SWMCB's Master Plan and the OEA's Policy Report.

A review of the 20 largest material categories by weight reflects the following:

• Source reduction opportunities exist for a number of materials, including food waste, OCC, wood pallets, mixed paper and office paper. For household bulky items like furniture and mattresses, reuse options are available in some areas.
• At least 8 of these material categories can be considered readily recyclable: OCC, wood pallets, recyclable mixed paper, office paper and boxboard.
• Opportunities exist to compost several of these categories, including food waste, non-recyclable mixed paper and diapers.
• Two of the 20 categories, which in fact are the same material but from both residential and ICI sources, are considered as a problem material: treated wood.

Overall, the SWMCB's Master Plan focus on promoting source reduction and recycling of food waste and packaging materials (commercial and transport) is consistent with opportunities identified in the study.

Recommendations

As the SWMCB, MPCA and OEA consider moving forward, we recommend the following activities:

• Conducting generator-based waste studies to identify reduction and recycling opportunities at the point of generation;
• Promoting additional residential waste abatement efforts as at least half the remaining MSW is from residential sources; and
• Conducting additional field sorts of MSW facilities in Greater Minnesota.

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