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' Well Installation Report 7-Eleven Inc., Store#14117, 2725 Country Club Boulevard,Stockton, CA7 August 12, 1999 2.89 mg/kg, and 1.95 mg/kg (EPA 8020), respectively. TPH-G was detected in boring GP-15 at 15 feet ' BGS at 42,900 mg/kg. Soil boring GP-7 located further to the west did not contain any detectable BTEX, MTBE, or TPH-G concentrations. South of the former UST area maximum benzene and TPH-G concentrations were detected in GP-17 at 20 feet BGS at 12.5 mg/kg and 704 mg/kg, respectively. The ' highest MTBE concentration south of the former UST area was detected in GP-17 at 15 feet BGS at 32.4 mg/kg. Benzene, MTBE, and TPH-G were not detected in any of the soil borings drilled to the ' north of the former UST area. Elevated hydrocarbon concentrations were detected in boring GP-14, drilled immediately east of the former UST area; however, hydrocarbon concentrations declined in soil samples collected from MW-2 and GP-12 drilled further east of the former tank location and were not ' detected in boring GP-13, the easternmost soil boring. ' Vertically, MTBE (EPA 8260) was not detected below 20 feet BGS in any of the soil samples collected at the site with the exception of sample MW-4-25'which contained a concentration of 0.043 mg/kg, however, geoprobe soil boring GP-17 drilled adjacent to MW-4 did not contain MTBE concentrations below 15 feet BGS. The vertical extent of benzene and TPH-G near the source area were defined in boring MW-2 which was drilled to a depth of 50 feet BGS. Benzene was not detected below a depth of 35 feet SGS in samples collected from MW-Z; however, TPN-G was detected at a very low concentration (0 154 mg/kg) at 50 feet BGS which may be due to matrix interference with groundwater during sample collection. 5.0 WASTE DISPOSAL Seven drums of soil generated during the drilling activities at the site and one drum of auger rinse water ' were removed from the site by Belshire Environmental Services, Inc The seven drums of soil were transported to TPS Technologies, Inc. in Adelanto, California on August 8, 1999 for proper disposal. On July 29, 1999, the one drum of auger rinse/well purge water was transported by Nieto & Sons to DeMenno Kerdoon in Compton, California for recycling (Appendix D). ' 6.0 SUMMARY ' On May 13 and 14, 1999, four groundwater monitoring wells were installed to a depth 25 feet to 30 feet BGS. Based on the reported concentrations of BTEX, TPH-G, and MTBE in the soil samples collected ' during the installation of the four monitoring wells and 17 geoprobe soil borings, the lateral and vertical 1 1 Jwell fl