Mica Landfill

The Mica Landfill is located in Spokane County, Washington approximately 15 miles northwest of Mica. The current status of the facility is closed and undergoing Clean-Up Action. Its last Ecology Five-Year Review occurred in 2013.

Historic Timeline

Year Occurrences
1981 Spokane county initiated a three-year groundwater investigation at the landfill.
1985 EPA placed landfill site on National Priorities List (NPL).
1988 Phase One of Remedial Investigation performed.
1991 Landfill closed to waste disposal.
1992 Phase Two of Remedial Investigation performed.
1992 Interim Action (IA) implemented to perform groundwater monitoring while negotiating actions to be performed at the site.
1994 Cover construction and components completed. Compliance monitoring of groundwater, leachate, and landfill gas began.
2001 Final Clean-Up Action Plan completed by Washington State Department of Ecology, consent decree finalized.
Ongoing operations, maintenance, and compliance monitoring being performed.

Indicator Substances for Groundwater Monitoring

Type of Indicator
VOCs 1,2-Dichloroethane, 1,2-Dichloropropane, Acetone, Benzene, cis-1, 2-DCE, Methylene, Chloride, Tetrachloroethane, Toluene, Trichloroethene, Vinyl Chloride
SVOCs Bis(2-ethylhexyl)phthalate
Metals Arsenic, Barium, Lead, Manganese, Mercury, Vanadium, Zinc

Clean-Up Action Components

System Description
Landfill Cover System
50 millimeter HDPE geomembrane layer underlain by a geosynthetic clay layer, passive gas extraction system, leachate collection system, and stormwater control.
Gas Extraction System
Passive landfill gas collection system with two active flares.
Institutional Controls
Restrictions placed on access to groundwater and land use at site.
Groundwater Compliance Monitoring
Includes a network of 15 groundwater monitoring wells.