Centralia Landfill

Environmental cleanup is complete at the site and the third periodic review shows the cleanup work remains effective in protecting the health of people and the environment.

The site is a closed municipal solid waste landfill. The cleanup action involved containment of hazardous materials typical of municipal solid waste landfills. Because hazardous material was left in place at the site, an environmental covenant was filed with the county in 2001.

When an environmental covenant exists for a cleanup site, Ecology reviews site conditions about every five years to ensure the long-term effectiveness of the cleanup action. Ecology inspected the site on September 1, 2020. The current condition of the landfill cover appears in good condition. Site personnel regularly maintain installations at the the Site, control vegetation on the landfill cap surface, and maintain fencing and security. Groundwater and surface water conditions are monitored regularly, and landfill-generated gas (methane) is collected and destroyed. 

Institutional controls continue to eliminate possible exposure of people and the environment to the contained waste and contaminated groundwater. 

From April 22 to May 23, 2021, Ecology held a comment period to give the public an opportunity to comment on conditions at the site. No comments were received and Ecology finalized the third periodic review report. 

Third Periodic Report - Final

The Centralia Landfill site is located at 1411 South Tower Road in Centralia. The site operated as an unlined municipal solid waste landfill from 1958 until 1994. A total of 55 acres of the 87-acre site received waste. The Lewis County Central Transfer Station has been operating on the north end of the site since 1994.

In October 1985, Ecology conducted a preliminary evaluation of the landfill in conjunction with the U.S. Environmental Protection Agency (EPA). The landfill was determined to be a hazardous waste site. In 1990, it was placed on the federal National Priorities List and the Washington State Hazardous Sites List. The Hazardous Site List is a statewide list of contaminated properties. Ecology was designated the lead agency for site cleanup.

In 1994, Ecology and the Centralia Landfill Closure Group (a group of potentially liable persons) entered into a consent decree (legal agreement) to cleanup the site. A multi-layer cover system was placed on the landfill. The cover prevents stormwater from seeping into the buried material. The cover also directs clean surface water runoff into a wetland mitigation area south of the landfill.

A permanent landfill gas collection system was installed to collect gas being generated beneath the landfill cover. Decomposition of landfill material can give rise to methane gas. The gas must be collected and destroyed because it burns easily. To destroy the methane, a gas flare system was installed adjacent to the landfill entrance. Gas probes located along the collection system monitor the amount of gas being produced.

Groundwater monitoring wells were installed up- and down-gradient of the covered landfill area to monitor metal concentrations and other water quality conditions.

A surface water sampling station is located downgradient of the covered landfill area to monitor the condition of the water exiting the site.

Fencing was installed around the site to prevent anyone from making unauthorized entry to the landfill.  

The property owner is required to continue monitoring groundwater, surface water, and landfill gas as described in the updated Centralia Landfill 2020 Compliance Groundwater Monitoring Plan. 

Groundwater cleanup levels have not been met at the site. But the cleanup complies with cleanup standards because the long-term integrity of the containment has been met. 

The remedy at the Centralia Landfill is considered protective of human health and the environment because the solid waste has been contained, landfill gas is collected and controlled, and surface water and groundwater are protected and monitored. 

An environmental covenant was recorded for the site in 2001. The covenant requires maintaining integrity of the cap covering buried landfill material and fencing to restrict public access to the site.

The covenant prohibits:

• Activities that will result in the release of contaminants contained as part of the cleanup without Ecology's approval.
• Restricts groundwater for any use other than for compliance monitoring. 
• Any use of the property that is inconsistent with the covenant.