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California Regional Water Quality Control Board <br /> Central Valley Region ;. <br /> Katherine Hart, Chair <br /> 1685 E Street, Fresno, California 93706 <br /> Linda S.Adams (559)445-5116 • Fax(559)445-5910 Edmund G Brown Jr. <br /> Acting Secretary for http://www.waterboards.ca.gov/centralvaIley Governor <br /> Environmental Protection <br /> RECEIVE® <br /> 25 January 2011 <br /> JAN 2 6 2011 <br /> ENVIRONMENTAL HEALTH <br /> Lee Higgins PERMIT/SERVICES <br /> Chevron Environmental Management Company <br /> 6001 Bollinger Canyon Road <br /> P. O. Box 6012 <br /> San Ramon, CA 94583 <br /> REVIEW — HUMAN HEALTH SCREENING EVALUATION, CATELLUS PROPERTY, TRACY, <br /> SAN JOAQUIN COUNTY, CA <br /> Chevron Environmental Management Company (Chevron) submitted a report entitled Human <br /> Health Screening Evaluation (Report), Catellus Property (Site), Tracy, San Joaquin County, <br /> CA. The Report, dated 20 October 2010, was prepared for Chevron by Science Applications <br /> International Corporation — Benham Companies, LLC (SAIC). <br /> Central Valley Regional Water Quality Control Board (Central Valley Water Board) staff has <br /> reviewed the Report and related 2006 — 2008 soil and groundwater investigation reports <br /> prepared for Chevron by SAIC and other consultants. Detailed comments, provided in the <br /> enclosed memorandum, are summarized below. <br /> Based on the findings, Central Valley Water Board staff concurred in a 15 April 2009 letter to <br /> Chevron, that crude oil affected soil and groundwater had been delineated, adequate <br /> monitoring data has been collected and a Screening Evaluation could be prepared. <br /> SAIC's Report determined that the potential onsite residential cancer risk was 4E-06, due <br /> primarily to the estimated oral and dermal exposures to benzo(a)pyrene and by dermal and <br /> inhalation exposures to benzene. The risk determined is within the range of risk management <br /> of 1 E-06 to 1 E-04 and SAIC indicated this is a conservative estimate, and actual risks are <br /> believed to be much lower. Therefore, according to the Report the exposure to petroleum <br /> hydrocarbons in shallow soil at the Site, should not result in an unacceptable health risk for an <br /> adult or child resident and was within the range of risk management. The total potential non- <br /> cancer hazard from oral, dermal, and inhalation exposure to onsite soils of 0.003 is well below <br /> the de minimus level of 1. <br /> Shallow groundwater at the Site exceeds State and Federal standards for total dissolved <br /> solids (TDS) for drinking water and agricultural purposes. SAIC concluded that Site <br /> groundwater is not a likely source of drinking water and the direct exposure pathway was <br /> considered incomplete. Therefore, SAIC did not quantitatively evaluate health risks and <br /> hazards of onsite groundwater for potential onsite residents. <br /> California Environmental Protection Agency <br /> C10ecycled Paper <br />