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Calitornzkegional Water Quality Co9rol Board <br /> Central Valley Region <br /> Karl E. Longley,SCD, PE, Chair QP <br /> Linda S. Adams Arnold <br /> 5ecretar�,for Fresno Branch Office Schwarzenegger <br /> Environmental 1685 E Street,Fresno,California 93706 <br /> X59 445-5116+Fax 559 445-5910 Governor <br /> ProlecNun � � � � <br /> http:/h"%-x waterboards.ca,gov/centr<ilvalley <br /> 20 June 2008 <br /> M. Scott Mansholt <br /> Chevron Environmental Management Company <br /> 6001 Bollinger Canyon Road <br /> Room K2066 <br /> San Ramon, CA 94583-2324 <br /> REVIEW OF ENVIRONMENTAL RISK EVALUATION — MOUNTAIN HOUSE <br /> DEVELOPMENT SITE #4, BYRON ROAD, MOUNTAIN HOUSE, SAN JOAQUIN COUNTY <br /> Regional Water Board staff reviewed the above referenced report dated 13 May 2008 for the <br /> Chevron Environmental Management Company (Chevron) Old Valley Pipeline <br /> (OVP)/Tidewater Associated Oil Company (TAOC) site, northwest of Tracy. Science <br /> Applications International Corporation (SAIC) prepared the report for Chevron. We also <br /> reviewed additional SAIC and Condor Earth Technologies soil and groundwater reports <br /> completed for Chevron between 2001 and 2006. The attached memorandum summarizes <br /> and evaluates the soil and groundwater investigation findings for the purpose of determining <br /> whether the remaining petroleum hydrocarbons identified at the site present an unacceptable <br /> human health risk and/or hazard as part of Chevron's receiving a determination of No Further <br /> Action Required for Mountain House Development Site #4 (Site #4). <br /> Site #4 is defined as an approximately 150 foot by 250 foot parcel primarily beneath Byron <br /> Road and the former OVP pipeline right-of-way (ROW) adjacent to and parallel the west side <br /> of Byron Road. Two active pipelines, Kinder Morgan and the Bay Area Products Line (BAPL) <br /> are adjacent to the former TAOC line along the east side of Byron Road. The historical OVP <br /> and TAOC lines, reportedly abandoned in the 1970's, transported heated crude oil from Kern <br /> County oil fields to refineries in the Richmond area until the late 1960's. <br /> Detailed Regional Water Board staff review comments are provided in the attached <br /> memorandum and summarized below. <br /> Regional Water Board staff finds that: <br /> • Affected soil and groundwater associated with the OVP/TAOC pipelines have been <br /> delineated and impacted soil removal is generally not feasible. <br /> • Elevated concentrations of total petroleum hydrocarbons (TPH) as diesel and gasoline, <br /> and benzene, toluene, ethylbenzene and xylenes were reported in soil and groundwater <br /> California Environmental Protection Agency <br /> (.s Recycled Paper <br />