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?j r. <br /> �cENED <br /> Lu­.�C B-m.Jit. <br /> M;.n ntv:HwNw.,s.r <br /> Water Boards <br /> - _Et3V1RN�ENTRAL <br /> HE.LM <br /> AMRISEVICES � SlN:v:Nrrknw/.kN.w,Uw4 <br /> -- <br /> Central Valley Regional Water Quality Control Board <br /> 8 May 2012 <br /> Michael N. Oliphant <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, US CAN-WELTY ROAD, VERNALIS, <br /> SAN JOAQUIN COUNTY <br /> Chevron Environmental Management Company (Chevron) submitted a report entitled Human Health <br /> Screening Evaluation (Report), US Can-Welty Road property (Site), Vernalis, San Joaquin County. <br /> The Report, dated 22 March 2012, was prepared for Chevron by Science Applications International <br /> Corporation Energy, Environment & Infrastructure, LLC (SAIC). <br /> Central Valley Regional Water Quality Control Board (Central Valley Water Board) staff has reviewed <br /> the Report and related soil and groundwater investigation reports, and file documents prepared for <br /> Chevron by SAIC and other consultants. Detailed comments, provided in the enclosed memorandum, <br /> are summarized below. <br /> Based on the findings, Central Valley Water Board staff concurred in a 20 April 2011 letter to Chevron, <br /> that crude oil affected soil and groundwater had been delineated, adequate monitoring data had been <br /> collected and a Screening Evaluation could be prepared. <br /> SAIC's Report determined that the potential onsite residential cancer risk from possible oral, dermal, <br /> inhalation exposures to onsite soils is within the range of risk management. SAIC indicated the risk <br /> estimate is conservative, and actual risks are believed to be much lower. According to the Report the <br /> exposure to petroleum hydrocarbons in shallow soil at the Site, should not result in an unacceptable <br /> health risk for an adult or child resident. <br /> The consultant queried the 2011 California Natural Diversity Database maintained by the California <br /> Department of Fish and Game to search for threatened, endangered, or sensitive species in the vicinity <br /> of the Site. The database identified six threatened or endangered species in the surrounding vicinity. <br /> There were no occurrences within one-mile of the Site-, the closest was the sighting of a Swainson's <br /> Hawk, approximately 1.6 miles from the Site. SAIC stated based on this information, a threat to <br /> sensitive ecological receptors does not appear to exist. <br /> SAIC concluded that no remedial action is necessary to protect human health or ecological receptors. <br /> and that a risk management decision of no further action required determination could be made. <br /> KAR_ E _ONOL°`- SCD. P.E.. CHAIP ! PAMELF C. CREEDON P.C.. BCEE. EXECUTIVE OFFICET+ <br /> 1685 F Slree'. Fresno GA 93700 www walerooaros ce.gowcen-rawalle, <br /> r.. r.:: _'.. <br />