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• California Regional Water Quality Control Board <br /> Central Valley Region <br /> r <br /> Linda S.Adams Arnold <br /> Secretary for Fresno Branch Office Schwarzenegger <br /> Environmental 1685 E Street,Fresno,California 93706 Governor <br /> Protection (559)445-5116•Fax(559)445-5910 <br /> litip://www.waterboards.ca.gov/centralvalley <br /> 15 December 2006 <br /> M. Scott Mansholt <br /> Chevron Environmental Management Company <br /> 6001 Bollinger Canyon Road, Rm K2066 <br /> San Ramon, CA 94583-2324 <br /> REVIEW OF SITE INVESTIGATION, TAOC TRACY GRAVEL PITS PROPERTY, TRACY, <br /> SAN JOAQUIN COUNTY <br /> Regional Water Board staff has reviewed the referenced report, dated 3 October 2006 <br /> prepared for Chevron and Union Pacific Railroad (UPRR) by Geomatrix Consultants, Inc. <br /> (Geomatrix). The project site, jointly owned by Chevron and UPRR, is located on Valpico <br /> Road, west of MacDonald Drive in south Tracy. The Old Valley Pipeline (OVP), Tidewater <br /> Associated Oil Company (TAOC) pipelines, and/or a pump station responsible for transport of <br /> crude oil were not directly associated with the TAOC Tracy Gravel Pits site. Detailed review <br /> comments are provided in the attached memorandum and summarized below. <br /> Gravel was previously quarried at the site and used for construction of rail lines. <br /> Subsequently, oily tank bottoms from the TAOC Tracy Pump Station site and UPRR boiler- <br /> filling spillage materials were disposed of at the site; other dischargers of miscellaneous <br /> materials included the City of Tracy, Laura Scudders' potato chip plant, local residents, and <br /> irrigation tail-water from local farms. <br /> Geomatrix and others completed previous site investigations between 1989 and 2005 for <br /> Chevron and UPRR. Results indicated that shallow soil within the gravel pit and in the north- <br /> northeast part of the site have been impacted by elevated TPH concentrations. <br /> The purpose of the investigations was to characterize site conditions and provide information <br /> to assist Chevron and UPRR to identify post-closure alternatives for the 34-acre property. Soil <br /> impact appears to be between depths of approximately 10 - 16.5-feet. <br /> Polynuclear aromatic hydrocarbon (PAH) benzo(a)pyrene (B(a)P) was present in soil with <br /> factors for carcinogenic PAHs that exceeded the Cal-EPA California Human Health Screening <br /> Levels in four borings. <br /> Organochlorine pesticides reported in shallow soil are less than the U.S. EPA Region 9 <br /> Preliminary Remediation Goals for residential risk-based screening levels and the dioxin <br /> results were below Cal-EPA's residential screening values. Furans and polychlorinated <br /> biphenyls (PCBs) were non-detect (ND). <br /> California Environmental Protection Agency <br /> (3 Recycled Paper <br />