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Scott Mansholt - 3 - 6 November 2006 Chevron — Catellus Property • SB-8 - at two and nine-feet, reported TPHc at 13,000 and 17,000 mg/kg, respectively; the 20.5-foot soil sample was ND for petroleum hydrocarbons; the lateral extent of affected soil surrounding SB-8 is defined by ND samples from borings SB-7, 9, 39 and downgradient borings SB-26 and 27. • SB-20 - at 21.5-feet was 2,300 mg/kg; the 4.5 and 8-foot samples from this boring reported TPHc at 5.4 and 98 mg/kg, respectively; the lateral delineation in this area is partially defined with TPHc at ND in SB-51, and 36 mg/kg in SB-18; • The vertical extent of affected soil is defined by SB-1 at 25.5-feet, SB-8 at 20.5-feet, and SB-15 at 21-feet; however, it has not been identified at SB-20 at 21.5-feet (2,300 mg/kg). Groundwater Results Sixteen groundwater samples were ND for TPH as diesel (TPHd); low TPHd concentrations (62 and 64 ug/1) for two samples was below the Water Quality Objective (WQO) of 100 ug/l for Taste and Odor; concentrations exceeding the WQO ranging from 170 to 900 ug/l was detected in seven samples; SB-16 and SB-18 reported 2,900 and 6,300 ug/I, respectively; BTEX was ND in all samples. Depth to water ranged from approximately five to 11-feet. A summary of affected groundwater is as follows: • TPHd in SB-1 was reported at 900 ug/I and two upgradient borings was ND for TPH compounds. • TPHd in groundwater was reported in borings SB-13 through SB-16, SB-18 through SB- 20 and SB-46. Boring SB-51, approximately 100-feet upgradient (south) of SB-20 and SB-31, 250-feet downgradient (north) of SB-12 and SB-13, were ND for TPH compounds. • PAH concentrations were less than the respective WQOs and ESLs for the majority of the samples except as follows: elevated concentrations of six and eight individual PAHs exceeded their respective ESL and/or WQOs primarily in SB-16 and SB-18 - the two borings having elevated TPHd present in groundwater and elevated TPHc in soil. Borings SB-13 and 14 had one PAH that slightly exceeded the WQO or ESLs. • Total dissolved solids (TDS) values ranged from 1,210 to 9,680 mg/l for seven representative grab groundwater samples. Except for the highest values (6,170 and 9,680 mg/kg), the TDS values (1 ,210 to 2,970 mg/1) are consistent with those documented at nearby Mountain House and City of Tracy OVP projects. Use of the shallow groundwater in Tracy is prohibited for domestic or municipal use by municipal Code for reasons unrelated to the OVP. • A well search of Department of Water Resources (DWR) files indicated that there are ten domestic-use water supply wells present within 2,000 feet of the site. Two wells within a few hundred feet and one well within one-quarter mile reported screen intervals