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Atlantic Richfield Company Page 8 ARCO Station No 4932,Stockton California August 29 2002 3.1.2 Subsurface Conditions Soils encountered during the drilling of DMW-2, DMW-3, and EW-2 consisted of clayey silt and silty clay from ground surface to approximately 10 feet bgs and silty sand to sand encountered from 10 feet bgs to the total depth of EW-2 (44 feet bgs) The deeper soils encountered in DMW-2 and DMW-3 consisted of silty sand to sand with small lenses of clayey sand were encountered from 44 feet bgs to total depth of the borings (84 feet bgs) Soils encountered during the drilling of MW-10 and MW-11 consisted of sand and silt mixtures from ground surface to the total depth of the boring, clay is present in two layers from 1 to 3 feet bgs and from approximately 35 feet bgs to total depth of borings (41 feet bgs) Groundwater was first encountered between approximately 24 and 30 feet bgs 3.1.3 Soil Sampling and Analysis Soil samples were collected at five foot intervals using a California-modified split spoon sampler in the field Selected soil samples were analyzed for TPHg, TPHd, and BTEX by the DHS/LUFT method, and fuel oxygenates by EPA Method 8260B TPHg, TPHd, and BTEX were not detected in any samples collected from MW-10, MW-11, DMW-2, DMW-3, and EW-2 MtBE by EPA Method 8260 was detected in one sample from DMW-2 (DMW-2, 40') at a concentration of 0 75 mg/kg MtBE was also detected in four soil samples collected from DMW-3 at concentrations ranging from 0 44 mg/kg (DMW-3, 55')to 13 mg/kg (DMW-3, 50') MtBE was also detected to two samples from EW-2 at concentrations of 2 3 mg/kg (EW-2, 40') to 9 3 mg/kg (EW-2, 35') MtBE was not detected_Z beyle, 30 feet bgs in any of the soil samplesand was also not detected in samples_from-MW-MW, ° �� 6961 f0 and MW-11 With the exception of MtBE, no other fuel oxygenates were detected in any - soil samples collected Soil analytical results are presented in Table 6 Field and laboratory procedures are presented as Appendix H Certified analytical reports, cham-of-custody documentation, and field notes are presented as Appendix I 3.1.4 Well Development, Sampling and Analysis,and Surveying On June 25, 2002, wells MW-10,MW-11, DMW-2,DMW-3, and EW-2 were developed by West Hazmat by rigorously surging over the length of the screen interval, and by purging between 10 and 12 casing volumes of water Groundwater samples were analyzed on July 12, 2002 as part of the third quarter monitoring and sampling Groundwater samples were analyzed for TPHg by EPA Method 8015, BTEX, MtBE by EPA Method 8020, and fuel oxygenates (MtBE, DIPE, TAME, EtBE, TBA,EDB, 1,2-DCA, and ethanol) by EPA Method 8260A I 1ARCO\49321PARIPAR doc