GRANT CO. AIRPORT
The Moses Lake Wellfield Contamination site is located about three miles northwest of the city of Moses Lake, Washington, in unincorporated Grant County. The Site encompasses potential source areas around the former Larson Air Force Base, and is currently the home of the Grant County International Airport. Potential source areas are scattered throughout the area, and approximately 1000 acres of groundwater are contaminated with trichloroethylene (TCE). The contamination is the result of operations of the former Larson Air Force Base and industrial activities associated with the aircraft industry. There are multiple potentially contaminated soil waste sites and several groundwater plumes of TCE that pose a threat to human health and the environment. TCE is a solvent used by industries to remove grease. EPA considers TCE highly likely to cause cancer in people. The contaminated groundwater plumes lie beneath and extend south from the former Larson Air Force Base. The U.S. Air Force used the base for a variety of purposes from 1942 until it was deactivated in 1963. Since 1966, when the base was disbanded and put up for sale, a variety of entities have acquired properties of the former base. The Port of Moses Lake acquired the largest parcel of property for use as the Grant County Airport. Other properties include commercial facilities and residences. The area surrounding the site is residential, agricultural, and commercial. The groundwater contamination was initially identified in 1988 by the Washington Department of Health during routine sampling of municipal drinking water wells. A number of municipal and private wells have contamination above EPA and state drinking water standards. Two of the contaminated municipal wells were part of a blended system that provides drinking water to approximately 5,000 people. The City of Moses Lake redeveloped their well system soon after the discovery of TCE to obtain clean groundwater from a deeper source. Between 1989 and 1993 the City fixed the three contaminated wells on the former base by deepening the wells. In 2003, EPA and the U.S. Army Corps of Engineers (USACE) completed deepening a groundwater well for a 100-home residential development served by the Skyline Water System. Both of these efforts occurred within the Moses Lake Wellfield Contamination site, and in both cases, clean groundwater was obtained from a deeper source. 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 Remedial Investigation/Feasibility Study (RI/FS) process was completed in 2007. Several TCE groundwater plumes were identified as well as multiple soil contamination areas, some of which are suspected to contain TCE and may contribute to groundwater contamination. EPA issued an Interim Record of Decision for the site cleanup in 2008. In 2010, EPA and the Army Corps of Engineers signed a cleanup settlement with Boeing, Lockheed Martin, and the City of Moses Lake. Boeing, Lockheed Martin, and City of Moses Lake will pay $3.25 million for cleanup and the federal government will pay $55 million. Site Responsibility: This site is being addressed through federal actions.
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