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Water Boards •ref Central Valley Regional Water Quality Control Board RECEIVED ED 20 November 2013 NOV 27 �M ENVIRONMENTTA'L HEALTH PERMIT/SERVICES Michael N. Oliphant Chevron Environmental Management Company 6001 Bollinger Canyon Road P. O. Box 6012 San Ramon, CA 94583 REVIEW - SOIL AND GROUNDWATER INVESTIGATION REPORT, TRACY RAIL YARD OFFSITE - EAST AREA, TRACY, SAN JOAQUIN COUNTY Chevron Environmental Management Company (Chevron) submitted the Soil and Groundwater Investigation Report (Report) dated 30 November 2012 for the Tidewater Associated Oil Company (TAOC; a Chevron predecessor company) Tracy Rail Yard Offsite - East Area (Site), in central Tracy. The report was prepared on behalf of Chevron by AMEC Environment & Infrastructure, Inc. (AMEC). The historical TAOC crude oil pipelines ran along the south side of the Site. Central Valley Regional Water Quality Control Board staff (Staff) comments on the Report and project files are listed below. The purpose of the investigation was to delineate the extent of total petroleum hydrocarbon m(TPH) chemicals in soil and groundwater crossgradient offsite to the east of the Tracy Rail Yard - 6 Street (TRY-6th Street) project (being investigated separately). The East Area project, adjacent to the east side of the TRY-6th Street project (vacant land), consists of single family residences. The Report describes that crude oil affected soil and groundwater was not observed and TPH as crude oil (TPHc) in soil samples was non detect (ND) or slightly over laboratory detection limits. Analysis of soil samples collected from boring East-2, drilled 40 feet east of the TRY —6th Street site boundary, reported concentrations of TPHc at 1.3 milligrams per kilogram (mg/kg) to 2.6 mg/kg at sample depths between five and 17 feet below ground surface (bgs). Analysis for the East-2 boring groundwater sample detected TPH as diesel (TPHd) at a concentration of 220 micrograms per liter. Groundwater sample results from cross- and downgradient borings off-set from the East-2 boring were ND for TPHd and related petroleum hydrocarbon compounds. Laboratory results for TPHc in soil samples from the off-set borings ranged from ND to 2.7 mg/kg at drilling depths ranging from five to 19 feet bgs. Analytical results for chemicals of potential concern (COPCs), i.e., volatile organic compounds and polynuclear aromatic hydrocarbons from all samples were ND. According to the investigative findings, the extent of crude oil affected soil and groundwater has been defined and no further characterization is needed. AMEC concluded that since COPCs were not detected in soil or groundwater and TPHc detections were minimal, and potential human exposure to the impacts is negligible. Since insufficient concentrations were detected, a human health screening evaluation could not be conducted. The Site should be closed based on existing information.