Greenacres Landfill

Overview

Greenacres Landfill, also called Liberty Lake Landfill, sits on about 58 acres roughly 14 miles east of Spokane in Spokane County, Washington. The landfill accepted household, industrial, and agricultural waste from 1951 to 1972. It was placed on the EPA's National Priorities List in 1984 after contamination was discovered in 1978. The site sits near residential neighborhoods and north of the Spokane Valley-Rathdrum Prairie Aquifer, a sole-source aquifer that supplies water to about 350,000 people for municipal, industrial, and agricultural use.

Contaminated groundwater is the primary concern at the site. EPA has identified 12 contaminants of concern, all found in groundwater. These include volatile organic compounds (VOCs) such as vinyl chloride, tetrachloroethene, trichloroethene, 1,2-dichloroethane, and 1,2-dichloroethene, as well as metals including arsenic, chromium, lead, and manganese. Bis(2-ethylhexyl)phthalate, antimony, and pentachlorophenol are also listed. EPA determined these substances pose an unacceptable risk to human health or the environment based on the contamination levels, potential exposure pathways, and possible health effects.

A remedial investigation and feasibility study ran from December 1984 through May 1991. EPA issued a Record of Decision in December 1992, selecting a remedy that includes capping the landfill, long-term groundwater monitoring, and institutional controls. Construction was completed on July 23, 1999. The cleanup was organized as a single operable unit. The Washington Department of Ecology provided oversight for the investigation and construction phases.

The site has achieved ready-for-anticipated-use status, meaning all cleanup goals for current and reasonably anticipated future land uses have been met and no unacceptable risks remain. EPA has confirmed that human exposure is currently under control and that contaminated groundwater has not spread beyond its original area. A cover system prevents direct contact with waste, a gas management system stops gas migration, and a stormwater system controls surface runoff. Institutional controls, including a restrictive covenant, prohibit water withdrawal, limit site access to maintenance, and bar any actions that could expose remaining contamination. The Washington Department of Ecology reviewed the site in August 2023 and confirmed the cleanup remains effective. Groundwater monitoring continues until water quality meets state standards.

Community members with questions can contact the EPA Remedial Project Manager or the Community Involvement Coordinator. Site documents are available through the Washington Department of Ecology's Eastern Regional Office or their site webpage, and inquiries can be directed to the state site manager.