| The Palermo Wellfield Superfund Site (Site) is located near Interstate Highway 5 and Trosper Road in Tumwater, Washington. The Site includes a City-operated water-supply wellfield and an adjacent residential neighborhood in the Deschutes River Valley (sometimes referenced in site documents as the Palermo Valley), as well as upland source areas including the current Washington State Department of Transportation (WSDOT) Materials Testing Laboratory (MTL), a former WSDOT MTL, and the Southgate Dry Cleaners business. Trichloroethene (TCE) was detected in the City water supply at the wellfield in 1993. Subsequent investigations identified a TCE groundwater plume over 3,000 feet (ft) long and 600 ft wide, and a smaller tetrachloroethene (PCE) plume near the Southgate Dry Cleaners site. USEPA Region 10 nominated the Site for an optimization review due an interest in updating the CSM and concerns regarding plume migration control and the potential for vapor intrusion (VI). |