Mica Landfill

Overview

Mica Landfill covers 65 acres near Mica, Washington. Spokane County and the City of Spokane ran it as a state-licensed municipal landfill from 1972 to 1991. The landfill took in residential and municipal solid waste, sewage sludge, demolition debris, and industrial materials, roughly 65,000 tons per year. That waste contaminated soil, sludge, and groundwater with hazardous chemicals.

EPA identified 18 contaminants of concern, all found in groundwater. They include volatile organic compounds (VOCs) such as benzene, trichloroethene, and vinyl chloride. Metals like arsenic, lead, mercury, and barium are also on the list, along with ammonia, nitrate, and various chlorinated solvents. These contaminants are tied to Operable Unit 01, the main remedial area.

The site was proposed to the National Priorities List (NPL) in 1984 and finalized on the NPL in June 1986. A remedial investigation ran from January 1988 to September 1992. The state carried out a removal action between June and October 1994. A feasibility study concluded in December 2001, when EPA issued a Record of Decision selecting institutional controls and monitoring as the cleanup approach. The long-term remedy also includes a landfill cover and engineering controls for leachate, stormwater, and gas collection and treatment. Construction ran from 1994 to February 2002. The site reached sitewide ready for anticipated reuse in September 2008.

EPA assessments show that human exposure is currently under control across the entire site. Contaminated groundwater migration is stabilized, and no unacceptable discharge to surface water is expected. All cleanup goals have been met for current and reasonably anticipated future land uses, and required land-use restrictions are in place. EPA continues monitoring groundwater to confirm contamination stays within its original area.

Community members with questions about the site can contact the Community Involvement Coordinator or the Remedial Project Manager.