US EPA - Environmental Protection Agency

$31m plan proposed to clean up groundwater at Moses Lake, Washington

A comprehensive clean-up plan for the trichloroethylene (TCE)-contaminated groundwater at the Moses Lake Wellfield Contamination Superfund site has been issued for public review by the U.S. Environmental Protection Agency (EPA). The site is located just north of Moses Lake and includes the Grant County Airport, the former Larson Air Force Base, and areas south of the airport.

“This cleanup plan takes steps that will protect human health and the environment and restore groundwater quality,” said Lori Cohen, EPA’s Associate Director of the Office of Environmental Cleanup.

The groundwater and soils at the site were contaminated with trichloroethylene (TCE) and other hazardous substances by operations of the former base and industrial activities associated with the aircraft industry. Approximately 1000 acres of groundwater are contaminated with TCE above health based standards and several contaminated soil waste areas are scattered throughout the site. The proposed cleanup is expected to cost about $31 million. TCE is an industrial solvent that was commonly used at this site for stripping paint from airplanes, washing airplane parts, and cleaning missile components.

The proposed cleanup plan calls for:

pumping out the most highly contaminated water and treating it to remove TCE;
cleaning up the contaminated soil areas by removing soils contaminated above safe levels;
restoring the groundwater to its highest beneficial use as a drinking water source; and
requiring local land use restrictions such as changes to local ordinances, zoning, and property easements to protect the public from contaminated groundwater and soils until cleanup work is completed.

The proposed plan gives background information about the Moses Lake site, describes the cleanup options EPA considered, and explains EPA’s recommended cleanup actions. EPA will choose a final cleanup plan for the site after careful review and consideration of information provided by the public during the comment period.

The public comment period starts January 7, 2008 and ends March 7, 2008.
EPA will host an open house on the cleanup plan on Wed., January 16, 2008, and a public meeting on Wed., February 13, 2008, both will be held from 6:30 to 9:00 p.m., at Big Bend Community College in Moses Lake.

In 1988, TCE contamination was found in three of the City of Moses Lake drinking water supply wells on the base. TCE contamination was also discovered in the Skyline Water System wells located south of the base. Since that time, EPA and the U.S. Army Corps of Engineers (Corps) have been investigating the contamination and cleanup options at Moses Lake. Between 1989 and 1993 the City fixed the three contaminated wells on the former base by deepening the wells. In 2003, the Corps constructed a replacement water supply well for the Skyline Water System. Continued testing has shown that the City and Skyline wells continue to provide reliable, clean drinking water to the community. The Corps and EPA continue to test a representative set of wells (up to 80) at the site. Based on this sampling, five homes have had whole-house filters installed at their wells to remove TCE from the water.

The safe level for TCE in drinking water is set at 5 parts per billion (ppb). The contaminated groundwater at this site contains TCE concentrations above 5 ppb and some areas contain TCE as high as 80 ppb. The primary risks for people who drink water containing TCE in excess of 5 ppb over many years are the potential to experience liver problems and an increased risk of getting cancer.

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