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• M. Scott Mansholt - 3 - 17 December 2008 Chevron Catellus Property non-detect (ND) for the remaining soil samples. PAH concentrations greater than screening levels for these boring samples were: a) benzo(a)anthracene, b) benzo(a)pyrene, and c) naphthalene. The ESL for benzo(b)fluoranthene was exceeded only in the sample from 9.5 feet bgs in SB-813. Remaining samples from the two borings at depths of 15.5 and 29 feet bgs respectively, were ND for TPH compounds. Subsequently, the result of the 2008 offset borings defined the lateral extent of affected soil for the Central area. The vertical extent of TPHc affected soil for the three areas of the Site was defined by ND results at depths between 29 and 36 feet bgs. Laterally, delineation was defined by ND results for the TPH constituents of samples from depths between 5 and 36 feet bgs. A fuel fingerprint evaluation of two samples from 11.5 and 15 feet bgs reported the petroleum hydrocarbons were consistent with weathered San Joaquin Valley crude oil. SAIC concluded that the lateral and vertical extent of crude oil affected soil for the Site has been delineated and additional characterization is not needed. Groundwater Groundwater samples from 23 borings, plus one duplicate and one sample from the DW Singh private well were submitted for analysis. Five of the samples, including the Singh well, were ND for TPH as diesel (TPHd). Analysis of ten samples detected low TPHd concentrations ranging between 59 and 93 micrograms per liter (pg/L). These TPHd concentrations are below the ESL and WQO taste and odor maximum concentration of 100 pg/L which is intended to limit general groundwater resource degradation. Analysis of seven samples detected TPHd concentrations between 110 and 180 pg/L and three had concentrations of 240, 270, and 270 pg/L. The latter results were for groundwater samples from three offsite borings completed northeast of the North affected area, and the former Tracy Pump Station facility. With the exception of benzene detected in groundwater at 0.30 pg/L in boring SB-813 where separate phase crude oil was noted, BTEX compounds were ND. Naphthalene was detected in this same boring at a concentration of 0.097 pg/L. In addition, low concentrations of two PAHs detected in two other borings from 0.0085 to 0.017 pg/L are equal to or slightly above respective ESLs and/or WQOs. According to SAIC's report, soil samples from boring SB-66 were unaffected. Analysis of a groundwater sample however detected TPHd at a concentration of 270 pg/L and ND for BTEX and PAHs. Borings SB-66 and SB-67 were drilled to evaluate groundwater conditions downgradient of the Singh well where reportedly, a diesel fuel spill was previously documented on Singh's property. The two borings and the Singh well were sampled to determine if diesel fuel impacted groundwater may exist at/near this location. The Singh and SB-67 groundwater samples were ND for TPH constituents. The up and downgradient extent of affected groundwater has been defined for the three different study areas indicated by ND results or TPHd concentrations at less than the ESLs and/or WQOs. The vertical extent of crude oil affected groundwater was defined by ND