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Lee Higgins -6 - 7 December 2010 Chevron, TAOC Tracy Rail Yard Soil Vapor Sampling Two offset locations (one in each unit) near borings previously reporting elevated TPH in soil and groundwater, and in close proximity to nearby residential areas, were chosen for soil vapor sampling (SV-C and SV-D). Samples collected from depths of five and ten feet bgs and analyzed for BTEX and naphthalene, were ND at respective laboratory reporting limits. However, low concentrations of toluene, ethylbenzene, and xylenes were detected in the four samples, but did not exceed the residential or commercial environmental screening levels. Operable Unit 5 Previously, numerous trenches were excavated, borings drilled, and samples collected and analyzed for delineating affected soil and groundwater on the west side of the parcel, adjacent and north of the former TAOC pipeline alignment. Findings presented in the earlier reports indicated that additional characterization was needed. The historical TAOC pipelines crossed generally east-west through the southern part of the parcel, extending offsite to the west and into the adjacent residential neighborhood. Several borings were completed offsite to the west of OU-5 from 2006 to 2008. During the recent investigation, eight offset borings were drilled for collection of onsite soil and groundwater samples. Four additional borings were drilled between 200 and 300 feet further north of the TAOC alignment, to collect groundwater samples at locations downgradient of previously identified crude oil affected areas. Offsite crude oil affected soil and groundwater will be addressed in the near future. Soil AMEC drilled offset soil borings and collected samples from locations where TPH compounds exceeding environmental screening levels were previously detected. TPHc was detected in 6 of 15 samples submitted, at concentrations ranging from 5.5 to 6,200 mg/kg at sample depths from 5 to 22 feet bgs. The two highest concentrations, 1,900 and 6,200 mg/kg, were detected in boring TRY-17, at depths of 5 and 17 feet bgs, respectively. Additionally, benzene, ethylbenzene, and xylenes were detected in the five-foot bgs sample at concentrations of 0.0008, 13, and 0.087 mg/kg. Benzene was detected in one other soil sample at a concentration slightly above the MDL. Toluene was ND for all samples. One soil sample from a depth of 17.5 feet bgs in boring TRY-19 within OU-5 along the former TAOC pipeline alignment was submitted for fuel fingerprint determination. Analytical laboratory chromatograms indicate the TPH present is consistent with weathered San Joaquin Valley crude oil. Analytical results indicated that PAH compounds were detected in 9 of 15 soil samples. The detections were carcinogenic PAHs; the BaP TEQs ranged from 0.0015 to 12 mg/kg. The highest TEQ value of 12 mg/kg was from a depth of five feet bgs in boring TRY-29. Affected material and detections of TPHc concentrations of 240 and 180 mg/kg were encountered at depths of 5 and 15.5 feet bgs, respectively. According to AMEC, the elevated PAH