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• Ptinary Environmental Assessment Report Pittman Elementary School,Stockton,CA December 10,2003 Page ii • did exceed the DTSC PRG in soil samples collected from around the Grant House, Grant House garage, the Rehabilitation Center, the Delta Center garage, Garage 1, and House 7. Concentrations of lead generally decreased with depth. The subsurface lead results were above the DTSC PRG in two samples (3638F-P9-D and 3638F-P58-D). The highest detected lead concentration was 4,600 mg/kg collected from the southern dripline of House 7. According to the DTSC Leadspread 7 Model, this concentration would result in blood lead levels of 102.2 micrograms per deciliter (µg/dL) in a child, well above the allowed 10 ltg/dL. One of the three paint chip samples collected from the warehouse building had a concentration of lead that qualifies it as lead-based paint. Natural Lias Field Concentrations of methane were detected in all soil gas samples but never exceeded 0.0009%by volume, far below the lower explosive limit of 5%. The low concentrations of methane measured in soil gas at the site pose no physical hazard.Hydrogen sulfide was not detected in any of the soil gas samples. Eastern Former Iindergiound Storage Tanks Site - Seventeen volatile organic compounds (VOCs) were detected in the soil gas samples and were identified as COPC. These chemicals were evaluated for risk and hazard using the Johnson and Ettinger Vapor Intrusion Model and were determined not to pose a significant cancer risk or health hazard. The compound 1,2-dichloroethane (1,2-DCA) was detected in one groundwater sample (VB-7), but not in any soil gas samples, collected closest to the former UST site (Figure 13, Appendix A), but does not pose a health threat at this site because groundwater occurs too deep (40 feet) to be exposed by construction activities, and will not be used for irrigation or consumption at the school. • Northern Former I indervround Storage Tanks Site Twenty VOCs were detected in the soil gas samples and identified as COPC. These chemicals were evaluated for risk and hazard using the Johnson and Ettinger Vapor Intrusion Model. The chemical 1,3- butadiene was determined to pose a cancer risk of 4.30E-06. The other detected VOCs were determined not to pose a significant cancer risk or health hazard. Acetone, benzene, 2-butanone [methyl ethyl ketone (MEK)], chloroform, methylene chloride, and toluene were detected in the groundwater samples (Figure 13, Appendix A), but do not pose a health threat at this site because groundwater occurs too deep (40 feet) to be exposed by construction activities, and will not be used for irrigation or consumption at the school. Polychlorinated Biphenyls No PCBs were detected in any of the surface samples collected by the electrical switching stations (transformers). Hydraulic Rlevator No PCBs were detected in the sample of hydraulic oil collected from the concrete floor in the hydraulic elevator shaft. CONCLUSIONS AND RECOMMENDATIONS Seven metals were identified by statistical tests as COPC and 43 other chemicals were chosen to be COPC based on their detectable presence in samples collected at the site. All 50 COPC underwent HHRA analysis in accordance with DTSC guidelines. Cancer risk and hazard quotients were calculated • for each COPC and summed. The cumulative lifetime cancer risk for all COPC is 1.84E-05 (18.4 in one `t �a CONDOR