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WELL CONSTRUCTION REPORT • USA STATION#110 - STOCKTON DECEMBER, 1995 3.8.2 Soil Analyses ' Soil samples were analyzed by a Sierra Laboratories a California certified laboratory in accordance with state guidelines and EPA protocol The samples were selectively analyzed for TPH quantitated against both gasoline (TPH G) and diesel (TPH D) standards and BTEX, using EPA methods modified 8015 and 8020,respectively Eight samples from each sort boring were analyzed for TPH and BTEX Of the 24 soil samples submitted for laboratory analysis none of the samples from MW-5 had detectable levels of TPH G, TPH D and BTEX, and only five samples from MW-4 and MW-5 had detectable levels of TPH G, TPH D and BTEX TPH G was only detected in sample MW-4 (40 5 to 41-feet), and was reported at a concentration of 0 063 ppm TPH D was not detected in any of the samples Benzene was only detected in sample MW-4 (40 5 to 41-feet), and was reported at a Nconcentration of 0 0033 ppm Toluene was detected in samples MW-4 (10 5 to 11-feet), MW-4 (40 5 to 41-feet), MW-6 (10 5 to 11-feet), MW-6 (30 5 to 31-feet) and MW-6 (50 5 to 51-feet) The levels of toluene detected ranged from 0 0032 to 0 0094 ppm Ethylbenzene was not detected in any of the samples Total xylenes were detected in samples MW-4 (10 5 to 11-feet), MW-4(40 5 to 41-feet), and MW-6 (10 5 to 11-feet) The levels of total xylenes detected ranged from 0 0033 to 0 0078 ppm The certified laboratory reports are presented in Appendix C and the results are summarized in Table 2 3.9 Survey The new well elevations were surveyed by Park on November 30, 1995 The TOC elevations are presented in Table 1 4.0 CONCLUSIONS Results of soil sampling and analyses detected low levels of BTEX in borings MW-4-P and MW- 6-P However, the concentrations were low and at variable depths Therefore, the data does not appear to indicate that any of the wells are located in areas where soil has been significantly impacted Results of the groundwater sampling and analysis reported TPH G,TPH D and BTEX all below the detection limits Results of the groundwater elevation survey indicted that the average gradient beneath the site is approximately 0 0027-ft/ft to the northeast 6