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M. Scott Mansholt - 2 - 17 December 2008 Chevron Catellus Property Current Investigation The purpose of the current investigation was to delineate the lateral and vertical extent of crude oil affected soil and groundwater partially defined during the June 2006 investigation. Impacted soil and groundwater previously designated as "North, Central, and South affected areas" were identified for additional characterization. To define the lateral and vertical extent of affected soil and groundwater, SAIC compared analytical results to applicable environmental screening levels. The screening levels are provided in: 1) U.S. Environmental Protection Agency Region 9, Preliminary Remediation Goals, October 2004 (PRGs) and 2) San Francisco Regional Water Quality Control Board - Environmental Screening Levels (ESLs) in Screening for Environmental Concerns at Sites with Contaminated Soil and Groundwater, Interim Final, May 2008. The analytical results from the investigations were compared to the respective PRGs and/or ESLs to estimate contaminant concentrations in soil and groundwater that are considered protective of human health. In addition, the Water Quality Objectives (WQOs) provided in the 2004 California Regional Water Quality Control Board document entitled Beneficial Use- Protective Water Quality Limits for Components of Petroleum-Based Fuels were considered in conjunction with the ESLs/PRGs to determine local groundwater quality parameters. The lowest and most conservative PRG, ESL, and/or WQO constituent concentrations applicable to the anticipated future site use(s) were considered in determining the extent of affected soil and groundwater. In May 2008, soil borings were completed and 44 soil and 25 groundwater samples were submitted for analysis of the petroleum hydrocarbon constituents. Two soil samples were submitted for fuel fingerprint evaluation to determine the type of petroleum hydrocarbons present. Depth to groundwater ranged from 5 to 15 feet below ground surface (bgs). The gradient is northeast as determined by monitoring well data from the adjacent OVP Tracy Pump Station property. Soil During the investigation, 26 borings were advanced to depths of 16 to 40 feet bgs. According to the analytical reports, soil sample results were less than applicable environmental screening levels except as described below. Total petroleum hydrocarbons as crude oil (TPHc), detected at 7,000 milligrams per kilogram (mg/kg) to 24,000 mg/kg, in borings SB-8B and SB-40 between 8 and 9.5 feet bgs, exceeds the applicable ESL for TPHc. Review of lithologic logs described separate phase oil (SPO) in boring SB-8B from approximately 7 to 14 feet bgs, extending to groundwater. Benzene, toluene, ethylbenzene, and xylenes (BTEX) were detected in the sample from 9.5 feet bgs at concentrations of 6.0, 2.1, 11.0, and 13.0 mg/kg, respectively. Analytical results of polynuclear aromatic hydrocarbons (PAHs) of four samples from SB-813 and SB-40 detected up to five PAHs were at or slightly exceeded respective PRGs/ESLs. The analysis of soil samples detected PAHs at or near the method detection limits or were