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URS Ms Margaret Lagorio Page 6 San Joaquin County Environmental Health Department June 27, 2003 the UST pit samples at a maximum concentration of 2 17 mg/kg Lead was detected at a maximum concentration of 5 3 mg/kg In the UST excavation (Secor, 1999b) Soil samples collected beneath the piping identified the following maximum concentrations TPHg in two of ten samples, 10 3 mg/kg, ethylbenzene in one of ten samples, 0 00632 mg/kg, xylenes in two of ten samples, 0 672 mg/kg, MtBE in four of ten samples, 102 mg/kg, and lead in seven of nine samples, 12 mg/kg Benzene and toluene were not detected at or above the reporting limit in the soil samples collected beneath the piping(Secor, 1999b) Soil samples collected beneath the dispensers identified the following maximum concentrations TPHg in one of eight samples, 1,170 mg/kg,xylenes in one of eight samples, 19 3 mg/kg,MtBE in one of eight samples, 0 204 mg/kg, and lead In six of eight samples, 16 mg/kg Benzene, toluene, and ethylbenzene were not detected at or above the reporting limit in the soil samples collected beneath the dispensers (Secor, 1999b) The UST pits were overexcavated to 18 feet bgs to accommodate installation of new USTs Soil samples were collected and analyzed for TPHg, BTEX, and MtBE No analytes were detected at or above method reporting limits with the exception of one sample that identified trace MtBE at 0 191 mg/kg (Secor, 1999b) Sampling results are presented in Attachment G Stockpiled soil was sampled and transferred to Forward Landfill in Stockton, California Groundwater was not encountered during these removal activities(Secor, 1999b) Quarterly sampling was restarted at Wells IA, W-2, W-2A, W-2B, W-3, and W-9 in January 2000 Results of sampling through June 2003 is presented in Tables 1 and 2 2000 Groundwater Pumping During quarterly groundwater sampling activities, oil and grease were Identified in well W-9 (430 mg/L soil and grease and 113 parts per billion [ppb] TPHg)although there had been no reported concentrations of petroleum hydrocarbons in this well previously A technician sampling the well stated it looked as if used oil had been poured down the well On October 27, 2000, approximately 200 gallons of water were extracted from well W-9 Subsequent sampling of well W-9 on November 1, 2000 included analyses for TPHg by EPA Method 8015, BTEX and MtBE by EPA Method 8020, Oil and Grease by EPA Method 413 1, Total Lead by EPA Method 6010A, and chlorinated hydrocarbons by EPA Method 624 No analytes were detected at or above reporting limits Extracted groundwater was hauled to ARCO's purge waster holding tank in West Sacramento then to Seaport Environmental in Redwood City, California, for disposal (Secor, 2000) r K 1WprocessV5 BP ARCOW04341Closure RequesOStation 434 Closure Doc doc