The Centralia Municipal Landfill covers 87 acres in Centralia, Washington, and operated as an unlined facility from 1958 to 1994. It accepted municipal and industrial waste, including soil contaminated with polychlorinated biphenyls (PCBs), paint waste, and pesticide waste. Contamination spread across roughly 55 acres, affecting soil, groundwater, and surface water. The site was placed on the federal National Priorities List (NPL) in 1990 after Washington Department of Ecology and the EPA evaluated it in 1985.
The main contaminants of concern are arsenic, chloride, iron, and manganese, all found in groundwater. Arsenic has also been detected in surface water. Health risks center on people ingesting or coming into contact with contaminated groundwater or leachate.
Cleanup began with a removal action in 1991. A combined investigation and feasibility study ran from 1993 to 1998, and the final remedy was selected and built in 1999. The remedy includes a permanent multi-layer cover system over a 46-acre area, a landfill gas collection and flare treatment system, perimeter fencing, and deed restrictions that limit land use to prevent human exposure. Zoning restrictions also prevent residential development. The Washington Department of Ecology leads ongoing operations, maintenance, and monitoring. The most recent five-year review was completed in 2021.
Human exposure is currently under control across the entire site. Contaminated groundwater is stable within its original area, and groundwater conditions are improving, though cleanup goals at the point of compliance have not yet been fully achieved. The physical construction is complete, and the site reached sitewide ready for anticipated reuse status in 2010. One business now operates on-site, employing 22 people and generating roughly $3.46 million in annual sales.
Community members with questions can contact the Washington Department of Ecology, or visit the Southwest Region Records Center at 7272 Cleanwater Lane, Olympia, WA 98504. The EPA's Community Involvement Coordinator and Remedial Project Manager are also available.
