As of 1993, Americans were generating approximately 207 million tons of municipal solid waste per year. Typically, this waste is landfilled, recycled, composted, or incinerated. There are more than 150 municipal solid waste combustors in the United States that incinerate more than 33 million tons of municipal solid waste each year. When municipal solid waste is combusted, the organic matter in the waste is completely destroyed. However, inorganic metal constituents, often including heavy metals such as lead, mercury, and cadmium, remain in the form of ash. About 25 percent of the total volume of the incinerated waste remains as ash, amounting to approximately eight million tons of municipal solid waste combustion ash generated annually in the United States.

EPA used to allow municipalities to dispose of their municipal solid waste combustion ash as a non-hazardous waste. The Agency felt that since the ash was derived from non-hazardous municipal waste, which can be disposed of in municipal solid waste landfills, the ash itself could be disposed of in unregulated facilities as well. A 1994 court case, however, rejected this position, and municipalities are now required to treat their combustion ash as a potentially hazardous waste, under the purview of the Resource Conservation and Recovery Act (RCRA).

RCRA regulates the management and disposal of both solid and hazardous waste by encouraging resource conservation and proper management of non-hazardous solid waste as well as by establishing a national "cradle-to-grave" management system for the tracking and control of hazardous wastes. All hazardous wastes must be managed in accordance with the strict requirements of RCRA Subtitle C. Waste that is considered non-hazardous is generally regulated by state and/or regional programs, as called for under RCRA Subtitle D.

Do the Municipal Waste Combustion Ash Requirements Apply to Your Community?

Yes, if your community owns or operates a municipal solid waste combustion facility you must be sure to manage your combustion ash in compliance with all applicable federal and state regulations.

Actions Your Community Should Be Taking

The first step you must take is to determine whether or not your municipal solid waste combustion ash is hazardous, as defined by RCRA. A solid waste is hazardous, for purposes of RCRA Subtitle C, if it either:

• has been specifically listed as hazardous, or
• exhibits one of four designated hazardous characteristics: ignitability; corrosivity; reactivity; or toxicity.

Ash from municipal solid waste combustors is not listed as a hazardous waste; therefore, your ash will only be subject to the requirements of Subtitle C if it is ignitable, corrosive, reactive, or toxic. Bear in mind, however, that if your ash does not meet the RCRA definition of a hazardous waste but is mixed with another waste that is considered to be hazardous, the entire mixture will have to be managed as a hazardous waste.

If your ash is hazardous you must be sure to comply with all of the Subtitle C requirements pertaining to the proper transportation, storage, and disposal of hazardous waste. Normally, this would include complying with the RCRA land disposal requirements (LDRs), which prohibit the disposal of any hazardous waste in or on the land, unless it has been properly treated. In the case of municipal waste combustion ash, however, EPA has not yet promulgated applicable treatment standards. Therefore, while you must be sure that your ash is managed in accordance with the requirements of RCRA Subtitle C and that it is disposed of in an approved hazardous waste disposal facility, you do not currently need to treat the ash to eliminate its hazardous constituents.

According to EPA, if your ash is does not meet the RCRA definition of a hazardous waste, you may dispose of it as you would any other type of solid waste, including disposing of it in a municipal landfill. Your state, however, may have its own special requirements for managing municipal waste combustion ash. Be sure to contact your state agency responsible for regulating waste disposal to determine what, if any, restrictions on the disposal of municipal waste combustion ash have been established.

Additional Information

The RCRA regulations are published in Title 40 Code of Federal Regulations, Parts 260 through 392.

EPA has established a toll free RCRA Hotline to answer questions regarding the applicability or interpretation of the RCRA regulations. Hours: 8:30 a.m. to 7:30 p.m. EST, Monday-Friday.

(See Resource Section for solid waste contacts)