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California Regional Water Quality Control Board <br /> Central Valley Regiono <br /> Katherine Hart, Chair <br /> 1685 E Street,Fresno,California 93706 <br /> Matthew Rodriquez (559)445-5116•FAX(559)445-5910 Edmund G.Brown Jr. <br /> Secretary for http://wwA'.waterboards.ca.gov/cetitralvalley vernor <br /> Environmental Protection RECEIVED <br /> 10 August 2011 AUG I 1 2011 <br /> Lee Higgins ENVIRONMENTAL HEALTH <br /> Chevron Environmental Management Company PERMIT/SERVICES <br /> 6001 Bollinger Canyon Road <br /> P. O. Box 6012 <br /> San Ramon, CA 94583 <br /> REVIEW — HUMAN HEALTH SCREENING EVALUATION, TRACY BYRON ROAD <br /> PROPERTY, TRACY, SAN JOAQUIN COUNTY, CA <br /> Chevron Environmental Management Company (Chevron) submitted a report dated <br /> 25 May 2011 entitled Human Health Screening Evaluation (HHSE; Report), Tracy Byron Road <br /> Property (Site), Tracy, San Joaquin County. The Report was prepared by Science <br /> Applications International Corporation — Benham Companies, LLC (SAIC). Central Valley <br /> Regional Water Quality Control Board (Central Valley Water Board) staff reviewed the Report <br /> and project related investigation reports prepared for Chevron by SAIC. The findings are <br /> summarized herein and detailed comments provided in the enclosed memorandum. <br /> In 2003, during installation of a City of Tracy stormwater drain system beneath West Byron <br /> Road, several areas of crude oil affected soil and groundwater were encountered. <br /> Subsequent investigations determined the origin was likely from the nearby historical Old <br /> Valley Pipeline (OVP) and/or the Tidewater Associated Oil Company (TAOC) pipelines. The <br /> historical pipelines, located along the south side of the Site, are within a right-of-way which <br /> also includes the Union Pacific Railroad (UPRR) tracks and active refined petroleum product <br /> pipelines. <br /> In a letter dated 16 February 2011, Central Valley Water Board staff notified Chevron that <br /> crude oil affected soil and groundwater had been delineated, and additional characterization <br /> was not needed. Central Valley Water Board staff concurred that the Site was a candidate for <br /> closure consideration and an HHSE could be prepared. Twelve separate crude oil affected <br /> areas indentified by the earlier investigations were evaluated as Area 1, 2, and 3 in SAIC's <br /> HHSE report. <br /> An incremental lifetime cancer risk of 1 E-06 (i.e., 1 in 1 million), in accordance with the <br /> National Contingency Plan, is used as a point of departure for the HHSE. SAIC's HHSE <br /> estimate of the potential cancer risk for an onsite resident was 3E-06 and 9E-07 for Areas <br /> 1 and 2, respectively. The potential cancer risk by direct contact for Area 3 was 4E-07. The <br /> level of cancer risk in Area 1 is within the risk management range of 1 E-06 to 1 E-04; the levels <br /> of risk in Areas 2 and 3 are below the de minimus level of 1 E-06. <br /> The non-cancer health hazard index for Area 1 and 2 are 0.004 and 0.005, respectively, are <br /> well below 1 and indicates an acceptable non-cancer health hazard for a hypothetical resident. <br /> California Environmental Protection Agency <br /> �a Rect-cled Paper <br />