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California egional Water Quality Con*l Board °.- <br /> Central Valley Region m <br /> Linda S.Adams Arnold <br /> Secretaryfor Fresno Branch Office Schwarzenegger <br /> Environmental 1685 E Street,Fresno,California 93706 <br /> Protection (559)445-5116•Fax(559)445-5910 <br /> Governor <br /> htip://www.waterboards.ca.gov/centralval ley <br /> 16 January 2007 <br /> M. Scott Mansholt <br /> Chevron Environmental Management Company <br /> 6001 Bollinger Canyon Road <br /> Room K2066 <br /> San Ramon, CA 94583-2324 <br /> OFFICE OF ENVIRONMENTAL HUMAN HEALTH ASSESSMENT(OEHHA) RISK <br /> ASSESSMENT REVIEW, FORMER TIDEWATER ASSOCIATED OIL COMPANY(TAOC) <br /> TRACY PUMP STATION, 880 BEECHNUT, TRACY, SAN JOAQUIN COUNTY <br /> Attached is a copy of the memorandum prepared by OEHHA summarizing its review of the 30 <br /> June 2005 Human Health Risk Assessment (HHRH), TAOC Tracy Pump Station, 880 <br /> Beechnut, Tracy, California. Geomatrix Consultants, Inc. (Geomatrix) prepared the HHRA on <br /> behalf of Chevron and Union Pacific Railroad (UPRR). For additional details regarding the <br /> Regional Water Board staff comments discussed below, as well as other issues, please refer <br /> to the attached OEHHA memorandum. <br /> The OEHHA report page numbers are bold and underlined and quotes from the OEHHA <br /> document are italicized. Regional Water Board staff comments follow each OEHHA <br /> reference. <br /> Limitations, page 2; paragraph 3 <br /> According to Geomatrix, all metals'concentrations were consistent with background <br /> concentrations. No comparison with background levels, neither explanation about the basis <br /> for this conclusion were found in the provided documents. <br /> Where metals analyses of petroleum impacted soil have been completed at this and <br /> numerous nearby OVP sites, the analytical results are within the range(s) expected for <br /> background soil values as documented by two studies for "background metals concentrations" <br /> in California soils. In addition, the analytical data for soil and crude oil from these sites are <br /> below the U.S. Environmental Protection Agency, Region IX, Preliminary Remedial Goals <br /> (PRGs). <br /> Site Background, pages 2-3; paragraph 3 <br /> The risk assessment is based on the assumption that the soil already collected in piles will be <br /> distributed and graded on site, i.e. that no soil will be moved off the site. <br /> Removal of the soil piles may reduce/eliminate potential health risk concerns at those <br /> locations. <br /> California Environmental Protection Agency <br /> Cpl Recycled Paper <br />