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ti. .. 04 Ocotber 2000 AGE-NC Project No. 00-0768 Page 2 of 7 Toluene, ethylbenzene and xylenes were present in the same samples analyzed at concentrations as high as 42 mg/kg 4,700 mg/kg and 27,100 mg/kg, respectively. The analytical soil results can be found in Appendix A. 2.3. PREVIOUS INVESTIGATIONS On 19 March 1991 the former UST pit was overexcavated to a depth of 14 feet bsg. Approximately 750 cubic yards of soil was removed from the former UST pit. Six sidewall and four bottom samples were collected from the finished excavation. Six sidewall and four stockpile soil samples were submitted for analysis. TPH-g was detected in soil samples LCSS-WW-8', LC-SP1, LC-SP3 and LC-SP4 at concentrations of 11 mg/kg, 68 mg/kg, 1.8 mg/kg and 19 mg/kg, respectively. Benzene, toluene,ethylbenzene and xylenes(BTEX)compounds,with the exception of benzene were detected in six of the ten soil samples at concentrations ranging from 0.013 mg/kg (toluene) to 15 mg/kg (xylenes). The analytical soil results can be found in Appendix A. On 27 March 1991 three ground water monitoring wells (MW-1 through MW-3)were installed at the site. Soil samples were collected at 5.5 feet and 10.5 feet bsg in monitoring well pilot borings MW-1 through MW-3. Soil samples were analyzed for TPH-g and BTEX compounds. None of the soil samples analyzed contained concentrations of TPH-g or BTEX compounds above the laboratory reporting limits. The analytical soil results can be found in Appendix A. On 27 February 1992 three additional ground water monitoring wells (MW-4 through MW-6)were installed at the site. Soil samples were collected at 5 feet, 10 feet, 15 feet and 20 feet bsg in monitoring well pilot boring MW-4, and at 15.5 feet bsg in monitoring well pilot borings MW-5 and MW-6.Soi1 samples were analyzed for TPH-g and BTEX compounds. None of the soil samples analyzed contained concentrations of TPH-g or BTEX compounds above the laboratory reporting limits.The analytical soil results can be found in Appendix A. From April 1991 to December 1995 the ground water monitoring well network on site was sampled on a quarterly basis. The last two monitoring events conducted in September 1995 and December 1995 showed nondetectable levels of contamination and closure of the site was requested. Analytical result of ground water samples collected from April 1991 to December 1995 can be found in Appendix A. On 13 February 1996 San Joaquin County PHS-EHD concurred with the closure request. Advanced GeoEnvironmental,Inc.