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collected from all eight borings drilled for this assessment. Toluene, ethyl benzene, total xylenes and MTBE concentrations also exceeded DTSC MCLS for drinking water in groundwater samples collected from several of the borings. Based on the groundwater flow direction at neighboring properties, the groundwater flow direction at the site is likely to the northwest. In December 1998, three 8,000-gallon gasoline USTs and their associated dispensers and piping were removed from the site. Approximately 300 tons of contaminated soil were excavated in the process and later disposed of off-site at the Forward Landfill. During the UST removal operations, samples were collected from the excavation, pipe trenches, stockpiles and water within the pit. Soil samples collected within the excavation contained up to 33 ppm TPH-G, 0.076 ppm benzene, 0.72 p p m toluene, 0.52 ppm ethyl benzene, 3 ppm xylenes and 0.71 ppm MTBE. Soil samples collected within the piping trenches contained up to 160 p p m TPH-G, 0.6 ppm benzene, 1 ppm toluene, 22 ppm ethyl benzene, 220 p p m xylenes and 2.5 ppm MTBE. Soil samples collected from the stockpiles contained up to 470 ppm TPH-G, 0.75 ppm benzene, 21 ppm toluene, 7. 1 ppm ethyl benzene, 44 ppm xylenes, 10 ppm MTBE and 6.5 ppm tertiary butanol (TBA). The groundwater sample collected from the UST excavation contained 66,000 ppb TPH-G, 2,700 ppb benzene, 10,000 p p b toluene, 720 ppb ethyl benzene, 12,000 ppb xylenes and 28,000 p p b r MTBE. In early 1999, two 10,000 gallon USTs were installed at the site in a different location on the property from the previous USTs. New lines and dispensers were also installed. The site is currently operating as a Unocal 76 Station. 3 . 0 PROPOSED SCOPE OF WORK (SOW) Based on the site history and discussions with Mr. Harlin Knoll of the San Joaquin County PHS-EHD, ASE has developed the following scope of work to provide necessary data for the site assessment. The proposed SOW is as follows: 1 ) Prepare a workplan for review and approval from the from San Joaquin County PHS-EHD. 2 ) Obtain the necessary drilling permit from San Joaquin County PHS- EHD. 574 West Grand Line Road, Tracy, CA Workplan — June 2000 -2-