MSW Taxonomy

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Presented at a meeting of the Superfund Committee of the Environmental Law Section,
State Bar of Michigan, 12/6/97

Municipal Solid Waste (MSW) is a term used to refer to a wide variety of waste sources. EPA chooses to define the term slightly differently depending on the context in which it is being used. I
n the MSW Settlement Proposal (1) MSW is defined to be "solid waste that is generated primarily by households, but that may include some contribution of wastes from commercial, institutional and industrial sources as well." The definitions are critical as they create settlement opportunities under the proposal.


Solid waste, according to RCRA (2), is generally anything discarded with some specific exceptions . Most solid waste, when it goes to a landfill, goes to a Municipal Solid Waste landfill(3) (MSWLF) regulated under Subtitle D. The settlement proposal, as was the Interim Settlement Policy(4), is directed towards municipal landfills defined as those landfills which accepted MSW. Also allowed in MSWLFs are Industrial and Commercial Non-hazardous Process Wastes, Construction and Demolition Debris, Municipal Sludge, and Agricultural / Oil and Gas / Mining wastes. 

Some perspective on waste types and relative volumes is in order because most of the attention is directed at the Subtitle C "hazardous" wastes. Based on the 1993 RCRA Report, total hazardous waste generated by Subtitle C facilities was 210.6 million tons, of which 92.5% was process wastewater treated on-site. Waste sent off-site was only 8.2 million tons, of which 36% was wastewater. After deducting other processing, only 1.2 million tons (or 0.6%) of the total Subtitle C waste generated was sent to landfills (5)

Unfortunately, Subtitle D waste has no equivalent reporting requirement and volumes associated with it must be estimated using diverse sources. For 1995, EPA, in the Franklin Associates annual study, estimated that 207 million tons of municipal solid waste were generated.(6) Of that, 57%, or 118 million tons, was disposed of in landfills. The table below is a snapshot of the volume and types of waste disposed in MSW landfills by accounting for non-household waste, industrial special waste (ISW), and construction and demolition debris (CDD) in addition to MSW.





Description / Definition

Subtitle C HAZARDOUS WASTE(7) (Type 1 Landfill)

Listed and Characteristic, Small Quantity Generator

Code P, U, F, and D> 100 kg / mo and/ or > 1 kg / mo acute



Subtitle D Municipal Solid Waste Landfill Waste Sources

Conditionally Exempt SQG (8)

<100 kg / mo & < 1 kg / mo acute



Industrial (9) (Ind Special)(10)and Commercial

Process Wastes - Non Hazardous



Construction & Demolition Debris (CDD)



Municipal Solid Waste (By Source):

Industrial(11) "Trash"

Non-Process Manufacturing (Office, Packaging, Lunchroom)



Commercial(12) "Trash"

Non-Process Commercial (SIC other than 20-39) (Retail, Restaurants, Service) 




Hospital (non medical), Schools & Prisons




Hotel / Motel & Apartments / Condo / CampsIndividual Family, Curbside


Total Subtitle D



The actual distribution of waste types/sources in MSW landfills is markedly different than the general perception. Only about 55 percent of MSW itself is "household", the rest is the commercial "dumpster" box, the industrial compactor and the construction rolloff box. The MSW landfill has only about 44% "household" waste.

MSW Landfill Problem

In 1992, EPA estimated that municipal landfills (those owned by municipalities or which accepted municipal waste) constituted 20 percent of the sites on the NPL and that municipalities were otherwise "involved" as generators, transporters or arrangers at 25 percent of the NPL sites.(15) Commentary to the Conditionally Exempt Small Quantity Generator (CESQG) rule(16) cited studies showing that of the 163 MSW landfills studied, 146 (or 90 percent) had groundwater contamination and 73 (or 45 percent) had surface water contamination. Clean Sites Inc., and others, have suggested that EPA's NPL estimates are on the low side and that the percentage of sites involving municipalities as owners, operators or PRPs may be in excess of 33%(17).

Arguments advanced for MSW exclusion or limitation of municipal liability from the Superfund (CERCLA) allocation process are founded upon the twin assumptions that "residential" or "household" waste is the primary component of municipal waste streams, and that such waste is not hazardous. As demonstrated above, the first assumption has difficulty because of the diverse nature and volume of the "municipal" waste stream.

The second assumption has difficulty as well. There is a considerable body of evidence available concerning the hazardous nature of household waste and its potential impact at leaking landfills. Professor Rathje's work, better known as "The Garbage Project", suggests that 0.5% or more of household waste may be hazardous(18). Other studies have examined organic pollutants present in rural landfills with presumably no industrial component, versus urban landfills and found no differences(19).

The Michigan impact of the Settlement Proposal is difficult to estimate. A cursory evaluation of the Michigan Sites of Environmental Contamination List (Former MERA "List") shows 397 (or 15%) landfills or "dumps" on the list, few of which are in "final remedy". Informal discussion with knowledgeable people suggests that there are a large number of "town dumps" which closed, poorly, under other regulatory initiatives. They probably all leak.

In addition, the Michigan NREPA Standard exempts: "only those persons who arrange for transport and disposal of products or containers commonly used in residential households, in a quantity normally used in a residential household and which was used in the person's residential household"(20).

This is a very different standard for the MSW exemption. It's impact on allocation in contribution actions under NREPA in Michigan may diverge from that now found in CERCLA cost recovery litigation and in the CERCLA interpretations issued by EPA.

1. 62 FR 37231, July 11, 1997

2. 42 USC 6903 (27) "The term "solid waste" means any garbage, refuse, sludge from a waste treatment plant, water supply treatment plant, or air pollution control facility and other discarded material, including solid, liquid, semisolid, or contained gaseous material resulting from industrial, commercial, mining, and agricultural operations, and from community activities, but does not include solid or dissolved material in domestic sewage, or solid or dissolved materials in irrigation return flows or industrial discharges which are point sources subject to permits under section 1342 of title 33, or source, special nuclear, or byproduct material as defined by the Atomic Energy Act of 1954, as amended (68 Stat. 923) (42 U.S.C. 2011 et seq.).

3. 40 CFR 258.2 (1992). "A municipal solid waste landfill unit means a discrete area of land or an excavation that receives household waste, and that is not a land application unit, surface impoundment, injection well, or waste pile, as those terms are defined under 257.2. A MSWLF unit also may receive other types of RCRA Subtitle D wastes, such as commercial solid waste, nonhazardous sludge, small quantity generator waste and industrial solid waste. Such a landfill may be publicly or privately owned. A MSWLF unit may be a new MSWLF unit, an existing MSWLF unit or an expansion of a permitted facility."

4. OSWER Directive 9834.13, December 12, 1989

5. The preliminary Biennial RCRA Hazardous Waste Report, USEPA OSWER, (1995) at C-11.

6. Characterization of Municipal Solid Waste in the United States: 1996 Update, USEPA OSWER, (1996) at 5.

7. "For purposes of this section, regulated hazardous waste means a solid waste that is a hazardous waste, as defined in 40 CFR 261.3 that is not excluded from regulation as a hazardous waste under 40 CFR 261.4(b) or was not generated by a conditionally exempt small quantity generator as defined in 261.5 of this chapter." 40 CFR 258.20(b) .

8. In the preamble to the Conditionally Exempt Small Quantity Generator (CESQG) Regulations, the EPA estimated that of the 201,000 tons of CESQG hazardous waste generated, only 21%, or 43,000 tons, were sent to landfills, primarily because of recycling programs.

9. "Industrial solid waste means solid waste generated by manufacturing or industrial processes that is not a hazardous waste regulated under subtitle C of RCRA. Such waste may include, but is not limited to, waste resulting from the following manufacturing processes: electric power generation [SIC 49]; fertilizer/agricultural chemicals [SIC 28]; food and related products/by-products [SIC 20]; inorganic chemicals [SIC 28]; iron and steel manufacturing [SIC 38]; leather and leather products [SIC 33]; nonferrous metals manufacturing/foundries [SIC 33]; organic chemicals; plastics and resins manufacturing [SIC 28]; pulp and paper industry [SIC 26]; rubber and miscellaneous plastic products [SIC 30]; stone, glass, clay, and concrete products [SIC 32]; textile manufacturing [SIC 22]; transportation equipment [SIC 37]; and water treatment. This term does not include mining waste or oil and gas waste." 40 CFR 258.2 (1992).

10. Percentages and ratios for ISW, CDD and the industrial / commercial breakdown were taken from the May 1995 "Demonstration of Available Disposal Capacity for the Solid Waste Management Plan for Oakland County Michigan, Approved May 11, 1995

11. "non-processing waste generated at industrial facilities such as office and packing wastes" 40 CFR 245.101

12. "Commercial solid waste means all types of solid waste generated by stores, offices, restaurants, warehouses, and other non-manufacturing activities, excluding residential and industrial wastes." 40 CFR 258.2 (1992).

13. "Institutional solid waste means solid waste originating from educational, health care, correctional and other institutional facilities. 40 CFR 245.101

14. "Household waste means any solid waste (including garbage, trash, and sanitary waste in septic tanks) derived from households (including single and multiple residences, hotels and motels, bunkhouses, ranger stations, crew quarters, campgrounds, picnic grounds, and day-use recreation areas)." 40 CFR 258.2.

15. Main Street Meets Superfund: Local Government Involvement at Superfund Hazardous Waste Sites, Clean Sites, Inc., Jan 1992 at 5.

16. USEPA, Background Document for the CESQG Rule, EPA/530-R-95-021, NTIS: PB95-208 930, May 1995.

17. Id. Clean Sites at 11.

18. Rathje, W.L. et al., Characterization of Household Hazardous Waste from Marin County, California , and New Orleans, Louisiana, Household Hazardous Waste Packet #1: The Garbage Project, Dept of Anthropology, University of Arizona, July 1987.

19. Ferrey, Steven, The Toxic Time Bomb: Municipal Liability for the Cleanup of Hazardous Waste, 57 G.W. L. Rev. 197, 202 (1988)

20. MCL 324.20101 et seq., specifically 10126(1)(d)(ii)    (248) 203-7030
4931 Ranch Lane / Bloomfield Hills, MI 48302