Industrial Manufacturing Site
Kent Washington
The site was occupied by a 13,496 square foot metal parts machining and welding shop that specialized in fabricating swivel tube connections and fittings for pressurized hoses. The purpose for the investigation and subsequent cleanup action was to identify and present the proposed investigation methods to assess subsurface soil and groundwater, with emphasis in the area where chemicals were stored and used. Prior to the cleanup action a detailed Work Plan was prepared that specified the Quality Assurance and Quality Control (QA/QC) procedures that were followed to ensure that the investigation methods, assessment techniques, sample collection, field screening, laboratory analysis, and long-term groundwater monitoring resulted in data of sufficient quality to evaluate the exposure pathways at the identified areas of concern on the site. The objective for the cleanup was to meet the substantive requirements of Washington MTCA and its implementing regulations for chemicals of concern (COC) in soil and groundwater.
The contaminants were confirmed in the sampled media by a Washington accredited laboratory. The COCs included gasoline, motor oil, diesel, xylenes, ethylbenzenes, trichloroethene, chloroethane, and vinyl chloride. A suspect water well house may have contained a gasoline storage tank that was used to operate an irrigation water well pump or gasoline may have spilled onto the surface from gasoline-operated farm equipment during the 1940’s to the 1960’s. Chlorinated solvents were used for industrial cleaning and degreasing metal parts at the facility from about 1985 through 1992. Residues of chlorinated solvents were likely released onto the ground surface outside the plant from past land use activities north of the building and near the west property boundary. The cleanup activities included soil excavation and vacuuming, and sludge and water pumping. The maximum depth of the collected soil samples ranged from about 6 feet bgs to about 4.5 feet bgs across the areas of impact. A series of ten hydraulically advanced groundwater probes and one probed groundwater monitoring well were advanced to assess groundwater quality after the cleanup action. Groundwater in the open excavations was encountered about 3.5 feet bgs. About 439 tons of chemically impacted soil and 380 gallons of chemically impacted groundwater was loaded and transported to an off-site and licensed treatment and disposal facility. The goal of the cleanup action was attained by obtaining a No Further Action decision letter from ECOLOGY.
