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A The UNL1.soil sample contained 1.5 parts per million (ppm) MTBE, ;and the UNL2 sample contained 0.0055 ppm MTBE, which is just over the detection limit of 0.005 ppm. None of the other hydrocarbon compounds or fuel additives were detected in these samples. The diesel dispenser sample contained 140 ppm diesel and 2.4 ppm gasoline, but did not contain BTEX or MTBE. I The two WOT piping soil samples did not contain elevated levels of metals. Detected concentrations of L the metals were at least one order of magnitude less than the most conservative environmental screening j levels (ESLs). Both of these samples contained trace levels of the VOC tetrachloroethene (PERC) in concentrations that were an order of magnitude less than the most conservative ESL(Table 1). The source of the reported PERC is not known. Therefore, the workplan does not include any proposed I further investigative work in this area. The San Joaquin County Environmental Health Department(EHD) i sued a Notice of Responsibility (NOR) letter dated November 24, 2003 notifying PG&E that the site, as been placed in the Local Oversight Program. An accompanying cover letter dated November 25, 2003 requests that a workplan be E submitted to EHD by January 15, 2002. Appendix B contains these letters. Mr. Nule Henderson of EHD verbally granted an extension of January 30 2004 to Mr. Robert Gray of PG&E. I TOPOGRAPHIC AND GEOLOGIC SETTING j The Stockton Service Center lies at an elevation of about 21 feet above mean sea level (MSL). The L topography in the area is gentle. The nearest surface drainage is C`laveras River, located 900 feet north of the fuel facility. �I L I r A geologic map of the region (Wagner, et. al., 1990) indicates that the service center is underlain by the Quaternary Modesto Formation. The Modesto Formation is an alluvial fan deposit that typically consists of I discontinuous, lenticular clay and silt lenses interbedded with sand-rich sediments derived from the Sierra I i j Nevada Mountains. Based upon the site elevation and topography, groundwater beneathl the site is expected to occur at ten to k I thirty feet below ground surface (bgs). 5. L i PROPOSED SOIL INVESTIGATION The proposed soil investigation consists of the following tasks. i L { • Complete an EHD Drilling Application. 4 • Advance two soil probes, one near the diesel dispenser andiione near the UNL 1 dispenser. k M Examine recovered soil samples. I • Collect organic vapor measurements of soil samples using a photoionization detector(PID). i i • Collect three native soil samples from each probe at depths'of about 5, 7, and 9 feet bgs. L ! .j 402.331-04.10.doe 2 I F