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PRELIMINARY ENVIRONMENTAL ASSESSMENT • REPORT Pittman Elementary School Assessor Parcel Number (APN) 139-210-04 Stockton,San Joaquin County, California EXECUTIVE SUMMARY Condor Earth Technologies, Inc. (Condor) conducted a Preliminary Environmental Assessment (PEA) for the proposed Pittman Elementary School site (Figures 1 and 2, Appendix A) located in Stockton, California in general accordance with the Preliminary Environmental Assessment Work Plan, prepared by Condor and dated April 21, 2003, and revised July 2, 2003. The work plan was approved by California Environmental Protection Agency, Department of Toxic Substances Control (DTSC) on July 28, 2003. The primary objectives of the work described in this report were to evaluate potential contamination issues and contaminant exposure levels associated with historical land use practices at the site. The site is located on an approximately 14.5-acre portion of the California State University — Stanislaus, Stockton Multi-Campus in Stockton, San Joaquin County, California (Assessor Parcel Number (APN) 139-210-04]. The site is located in downtown Stockton in a mixed residential and commercial area. According to the Geological and Environmental Hazards Assessment Report, prepared by Condor, dated August 7, 2002, the site has primarily been used for institutional purposes as a state hospital and a • developmental center. Potential contamination issues primarily include residual pesticide concentrations in surficial soils, hydrocarbon releases from former underground storage tank (UST) sites north and east of the site, polychlorinated biphenyl (PCB) releases from electrical transformers, methane and hydrogen sulfide in soil gas from the Stockton Gas Field, lead-impacted soil from lead-based paint, and selected metals concentrations in these soils. Potential exposure pathways include inhalation, absorption, and ingestion. Condor personnel collected environmental samples at the site between August 6 and 20, 2003. The approximately 14.5-acre site was evaluated by seven sampling schemes, each evaluating possible contamination in particular areas based on past uses of that area. Soil samples, soil gas samples, and groundwater samples were collected for this PEA. I awn Area All metals and pesticides identified as chemicals of potential concern (COPC) underwent human health risk assessment (HHRA). Hexavalent chromium, cobalt, and dieldrin were the primary contributors to elevated cancer risk (greater than one chance-in-a-million over a lifetime). The chromium and cobalt samples that contributed significantly to the overall risk (L3, L7, and L9) were located in the northern portion of the site (Figures 9 and 10, Appendix A). The samples of dieldrin that contributed significantly to the overall risk (L9 and L15/L16) were located near structures (Figure 8, Appendix A), a fact consistent with the use of these chemicals in pest control and gardening applications. Structure Thi In ines Lead was detected in all of the surface soil samples (Figure 11, Appendix A). Concentrations of lead in soil did not exceed the DTSC Preliminary Remediation Goal (PRG) of 255 mg/kg around the warehouse, sewage lifting station, Delta Center, Houses 1 through 6, and Garages 2 through 4. Lead concentrations 1 , �.a CONDOR