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Ms Vicki McCartney Project No 88004OIA 0201 <br /> October 26, 2004 <br /> Page 3 <br />' depth of 90 feet bgs Groundwater samples were collected from hydropunch borings <br /> advanced adjacent to each CPT boring location Four discrete water samples were <br /> collected from each hydropunch boring Soil encountered beneath the site during this <br /> investigation consists of interbedded gravelly sand, sand, silty sand, sandy silt, silt, <br /> sandy clay, silty clay and clay There appears to be laterally continuous sand beds at <br /> depths of approximately 8 to 15 feet bgs and 28 to 40 feet bgs Below these sand <br /> horizons are many discontinuous thin layers of clay and other stiff, fine-grained material <br /> PROBLEM ASSESSMENT <br /> This section provides information requested by the California RWQCB characterizing <br /> the extent of impact at the site based on the results of previous investigations This <br /> information provides the basis for making remedial action decisions <br /> Soil Conditions / ) �� � <br /> Shallow soil at the Asect site has en impacted with el hydrocarbons at <br /> Sa m 116 <br /> concentrations up to 20, -p -liter (µg/l) of total e oleum hydrocarbons as <br /> gasoline (TPHg), -0-0272 lt; o benzene, and 49-4- lLK -of MtBE The highest <br /> I <br /> hydrocarbon concentrations have been present in soil beneath the western dispenser <br /> islands Appendix A contains historical soil chemical analytical data <br /> Groundwater Conditions <br /> Hydrocarbons have been reported in groundwater beneath the site at concentrations up to <br /> 25,700 µg/l ofTPHg (well MW-1), 1,820 pg/1 of benzene (well MW-1), and 41,000 pg/l <br /> of MtBE (well MW-5) On August 12, 2004, TPHg range hydrocarbons were reported <br /> in wells MW-1, MW-3, and MW-5 at concentrations of 1,100, 150, and 54 Pg/l, <br /> respectively Benzene was reported in all wells except MW-2 at concentrations ranging <br /> from 0 79 µg/1 (MW-3) to 86 pg/l (MW-1) MtBE 1s reported at concentrations ranging <br /> from 13 pg/1 (MW-3) to 2,500 µg/l (MW-2) in all wells at the site 'In CPT borings <br /> CPT-3 and CPT-4 advanced in September 2003, groundwater samples collected at <br /> 25 feet bgs had concentrations of MtBE at 7,600 and 12,000 pg/l, respectively <br /> rNs� <br /> N 1sacDP170041Pg188018800409A 4ad doc Shaw Environmental,Inc <br />