Mary Ellen Murphy

In May 1994, the Supreme Court ruled that toxic ash generated by a resource recovery facility from in-cinerating municipal solid waste (MSW) is not automatically exempt from regulation as a hazardous waste under Subtitle C of RCRA (City of Chicago et. al v. Environmental Defense Fund et. al. No. 92-1639). As a result, ash from MSW incinerators must be tested for hazardous characteristics.

Over the past year, the waste-to-energy (WTE) industry has adapted to the regulatory changes. Before the ruling, the Solid Waste Association of North America (SWA-NA) surveyed state regulators and members who own/operate facilities, and found that most facilities al-ready were managing their ash in an environmentally-sound manner (see table).

Completed surveys were submitted by 32 states operating 104 plants and burning a total of approximately 14,000 tons of MSW per day. Approximate-ly 25 percent of the states required some testing of WTE ash. Also, Al-abama, Connecticut , Mississippi, New Mexico, Tennessee, Vermont, Washington and Wisconsin require ash disposal in monofills.

On the other hand, 18 states al-low co-disposal with MSW in non-hazardous landfills. In addition, some states have established protocols for ash sampling; others require an ash management plan for each municipal waste combustor and/or disposal facility.

The survey also reported that 20 states require ash to be transported in covered trucks, 17 require watertight trucks and six require the vehicles to be washed before they exit the loading area. In Con-necticut, maximum water content in the ash is 30 percent. Illinois re-quires a manifest to be displayed on each of the trucks. New Hamp-shire and Pennsylvania require wetting the ash to avoid dispersion; in Vermont the ash must be stored in individually-marked containers.

In addition, 46 facilities which generate a total of 224 tons of ash per day submitted surveys (see ta-ble). The facilities report two methods to test ash: the more frequently used toxicity leaching characteristic procedure (TCLP) and the EP toxicity test. Most of these facilities also test for other materials in-cluding total metals, moisture and pH. In addition, one facility uses the California Title 22 waste extraction test, one uses the total metals test, four use the 13 priority pollutant metals test and two use the Environmental Protection Agency's (EPA) leaching potential method 1312.

The respondents report using the following stabilization methods:

* cement (three facilities);

* lime (eight facilities);

* acid (two facilities);

* a combination of acid and lime (two facilities);

* a combination of acid and kiln dust (one facility);

* kiln dust (one facility); and

* boiler blow-down water (one facility).

Eight facilities reuse their ash either as ag-gregate for constructing site/landfill roads; as daily, intermediate and final cover for landfills; for landfill berm construction; as asphalt concrete; or as aggregate in concrete blocks to construct on-site buildings.

Since the Supreme Court's decision, the EPA has issued several documents to address legal and policy issues. The latest document determines that the ash is subject to RCRA Subtitle C when it exits the facility. At that point, the facility's op-erater must determine whether the ash exhib-its the toxicity of a hazardous waste, which determines whether land disposal restrictions apply.

The EPA interpretation is meant to protect human health and the environment. It also avoids retro-fitting ash handling systems, which would be required at many facilities if the ash were regulated inside the building. In addition, this interpretation serves Congress's intent to encourage resource recovery fa-cilities and to remove impediments to their operation.