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1 ' 36 Well Survey To establish the horizontal position relative to pertinent site features and elevation with ' respect to mean sea level, the new wells were professionally surveyed by Morrow Surveying of West Sacramento, CA on September 15, 2004 The survey maps are included in Appendix E ' 37 Soil Analytical Results ' All soil samples were analyzed for TPHg, BTEX, and the five fuel oxygenates MtBE, ethyl tertiary butyl ether (EtBE), TAME, TBA, and di-isopropyl ether (DIPS) by EPA Method 8260 (Table 1) ' BTEX, TPHg, DIPS, EtBE, TAME and TBA were not detected above the laboratory reporting limits in any of the soil samples analyzed MtBE was detected in MW-8, MW-9, and EX-1 at concentrations ranging from 0 0090 mg/kg to 0 37 mg/kg (Table 1, Appendix F) ' The analytical results from soil samples collected during this investigation are similar to results found in previous soil samples collected from the site No BTEX, TPHg, DIPE, or EtBE with concentrations above laboratory reporting limits were detected in soil samples ' collected from this site (Table 1) TAME has been detected (0 0091 mg/kg) in one soil sample and TBA was detected in two soil borings (MW-5 and MW-613) in concentrations ranging from 0 012 mg/kg to 2 2 mg/kg (Table 1) 38 Groundwater Analytical Results ' Groundwater samples collected from CPT-1 contained concentrations of 69 ug/L TPHg and 0 74 ug/L MtBE in the sample collected at 60 feet bgs BTEX, TBA, DIPE, ETBE, and TAME were not detected above the laboratory reporting limits No detectable concentrations of ' BTEX, TPHg, MtBE, TBA, DIPE, ETBE, or TAME were reported for the sample collected from CPT-1 at 82 feet bgs or from CPT-2 at 65 and 81 feet bgs (Table 3 and Appendix F) ' Quarterly groundwater monitoring and sampling was conducted on July 30, 2004 BTEX, TPHg, TBA, DIPE, ETBE, and TAME were not detected above the laboratory reporting limits in any of the groundwater samples collected MtBE concentrations ranged from <0 50 ug/L ' (the laboratory reporting limit) to 17,000 ug/L (Table 3) Certified laboratory analytical data and chain-of-custody documentation are included in Appendix D and field notes are included in Appendix B ' 4.0 GEOLOGIC AND HYDROGEOLOGIC SETTINGS ' 41 Lithology Lithology beneath the site generally consists of fine grained silts with minor clay and sand ' lenses from ground surface to approximately 60 feet bgs and from 65 to approximately 80 feet bgs Silty sand and sand are present at the intervals of approximately 60 to 65 feet bgs and 80 to 83 feet bgs (the total depth explored) A high permeability sandy silt was 32262 Assessment&Feasibility Report&SCM doc 6 September 30,2004 77EL 32262 04 0502