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N� I --_ .-- wf. T=. " 'N" ,' r -ter -skks' et- .. - x x 3. 1 soil Borings and 2IM91jM Prior to commencement of drilling activities, permits for the proposed water monitoring wells were obtained from the SJCEHS. An encroachment permit was also obtained from the City of Tracy Department of Public Works for the work performed offsite within the public right-of-way along East Grantline Road. Copies cf the permits are presented in Appendix B. On April 30 and May 1, 1991, Alton Geoscience supervised the drilling of nine soil borings both onsite and offsite. Four of these borings were subsequently converted to ground water monitoring wells while the remaining five were converted into temporary wells. Further drilling along the median strip of East Grantline Road was prohibited by a representative of Chevron Company, U.S.A. due to the presence of three underground fuel lines (regular, unleaded, and diesel fuels) . The drilling activities were performed by West Hazmat Drillin(; Corporation of Rancho Cordova, California, using a truck mounted CME-75 drilling rig equipped with hollow-stem augers. soil Borings B-1, B-5, B-6, B-7, and B-8 were drilled to total depths ranging from 10 to 15 feet below grade using 8-inch augers. Each boring was converted into a temporary well, as described in Section 3.2, to conduct a qualitative ground water survey. After a ground water sample was collected and the temporary casing was removed, the borehole was backfilled from the bottom to the top with neat cement. Borings B-2, B-3, B-4, and B-9 were drilled to a total depth of 20 feet below grade using 8-inch hollow stem augers. Temporary casings were then installed in each borehole to collect ground water samples for the qualitative survey. All four of these soil. borings .were then converted to ground water monitoring wells. During drilling, soil samples were collected at 5-foot intervals using a modified California split-spoon sampler lined with clean brass sleeves. The soil sample sleeves were sealed using aluminum foil, plastic caps, and clear tape, and placed in an iced cooler prior to transport to a California-certified laboratory. Soil samples collected from Soil Boring B-3 at 6.5 feet below grade and from Soil Borings B-2, B-4, and B-9 at 6.5 and 11.5 feet below grade were submitted for chemical analysis. Field measurements of combustible gas in selected soil samples were recorded and included in the soil boring logs. 152, 5