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pit ii <br /> Tosco Corporation,A Subsidiary of Phillips Petroleum Company 4 <br /> Tosco Service Station No 4409,1502 North El Dorado Street,Stockton,Cahforma May 29,2002 <br /> depth of the sample The soil samples were analyzed for the presence of TPHg and <br /> BTEX by the California Department of Health Services/Leaking Underground Fuel <br /> Tank (DHS/LUFT) Method Soil samples were also analyzed for fuel oxygenates <br /> [tertiary butyl alcohol (TBA), MtBE, di-isopropyl ether (RIPE), ethyl tertiary butyl <br /> ether (EtBE), tertiary amyl methyl ether(TAME), and ethanol], 1,2-dichloroethane <br /> (1,2-DCA), and 1,2-dibromoethane (EDB)by EPA Method 8260B Soil samples <br /> were also analyzed for methanol by EPA Method 8015 Modified IT's field and <br /> laboratory procedures are presented in Attachment B Certified laboratory <br /> analytical reports and chain-of-custody documentation is presented in Attachment <br /> D <br /> • Groundwater Analytical Results. On October 10, 2001, Gettler-Ryan, Inc (GRI) <br /> developed and sampled the newly installed monitoring wells Groundwater samples <br /> were analyzed for the presence of TPHg, BTEX, and MtBE by EPA Methods 8015 <br /> Modified and 8021B, and for fuel oxygenates (MtBE, TAME, DIPE, EtBE, TBA, <br /> and ethanol), 1,2-DCA, and EDB using EPA Method 8260B IT's field and <br /> laboratory procedures are presented in Attachment B GR1's well development and <br /> sampling sheets, certified laboratory analytical report, and chain-of-custody <br /> documentation are presented in Attachment E <br /> • Well Surveying. Wells MW-8 through MW-10 were surveyed by Siegfried <br /> Engineering, Inc , a licensed surveyor for locations and elevations relative to mean <br /> sea level Well survey data is presented in Attachment F <br /> FINDINGS <br /> Subsurface Conditions <br /> Soils encountered to the maximum depth explored (approximately 80 feet bgs) consisted <br /> mainly of interbedded sandy silt, silt, clayey silt, and silty sand A more complete <br /> description of subsurface lithology is shown on the boring logs presented in Attachment B <br /> Saturated soils were generally encountered in all of the soil bonngs between 60 feet and 80 <br /> feet bgs Depth to water recorded in wells MW-8 through MW-10 on October 10, 2001 <br /> ranged from approximately 27 feet bgs to 3175 feet bgs Groundwater flows within the <br /> shallow zone toward the northeast at a hydraulic gradient of 0 003 foot/foot, and the flows <br /> within the deep zone toward the northwest and northeast at hydraulic gradients of 0 045 <br /> and 0 136 foot/foot,respectively Groundwater elevation contour maps constructed by IT <br /> for the shallow and deep zones are presented in Attachment G <br /> Soil Analytical Results <br /> TPHg was detected in five soil samples at concentrations ranging from 8 8 mg/kg (MW-9 <br /> @75')to 4,400 mg/kg (MW-9@60') Benzene was detected in four samples at <br /> concentrations ranging from 0 22 mg/kg (MW-8 @ 60') to 77 mg/kg (MW-9 @ 60') <br /> I(Tosco Markegng144091Reports\AsmtRpt doc <br />