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f Laborato Analysis Soil samples from borings SB 1, SB3, SB4, and SBS were analyzed by NEI/GTEL Environmental Laboratories, Inc for total petroleum hydrocarbons as gasoline, diesel, kerosene, and lubricating oil (TPHg, TPHd, TPHk, and TPHIo) by EPA Methods 8015 and 3350, benzene, toluene, ethylbenzene, and xylenes (BTEX) by EPA Method 8020, methyl tertiary butyl ether (MTBE) by EPA Method 8020, and total lead by EPA Method 3050A The soil sample collected from boring SB2 was not submitted for laboratory analysis RESULTS OF INVESTIGATION Site GeoIoev Native sediments encountered in soil borings SBI though SBS during field activities indicate that the upper 6 to 9 feet of the soil column consists primarily of clay (CL) Below 9 feet, fine to medium grained sand (SP) was encountered to a depth of 46 feet bgs, the maximum depth explored An apparent discontinuous clay layer was observed in SB4 at 30 8 feet bgs Fill (silty sand, SM) was observed in the upper 10 feet of soil boring SB3 Groundwater was not encountered during drilling activities Based on communications with PHS/EHD personnel, groundwater is estimated to be present at approximately 55 feet bgs Analytical Results Results of laboratory analyses performed on selected soil samples from the borings indicate that . total lead, detected in all the soil samples analyzed, is present beneath the site at concentrations ranging from 4 1 to 7 8 milligrams per kilogram (mg/kg) The analytical results were compared with the typical U S Mean and typical Bay Area concentrations in soil as presented in Summary of Typical Metals Concentrations in Soils and Surficial Materials, from US G S Professional Paper 1270 for the Conterminous United States (Attachment 2) In comparison, the lead detected appears to be at background concentrations Petroleum hydrocarbon constituents were detected in soil samples collected from boring SB3 at depths of 15, 20, and 45 feet bgs The highest reported constituent concentrations in this interior boring were observed in the soil sample collected at 20 feet bgs and include toluene (0 27 mg/kg), ethylbenzene (7 7 mg/kg), xylenes (40 mg/kg), TPHg (1,900 mg/kg), TPHk (470 mg/kg), and TPHd (77 mg/kg) The petroleum hydrocarbons appear to attenuate rapidly with depth as indicated by soil samples DP-SB3-30 and DP-SB3-45, collected at 30 and 45 feet bgs, respectively No hydrocarbon analytes were reported in sample DP-SB3-30 and low levels of aromatic hydrocarbons and TPHg(12 mg/mg) were reported in sample DP-SB3-45 No petroleum hydrocarbons were detected above laboratory method detection limits in soil samples collected from soil borings SB 1, SB4, and SB5 Analytical results are summarized in Table I Laboratory data sheets and chain-of-custody documentation is presented in Attachment 3 • w W735Vq)ortslsum&c 3 SMTH