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f <br /> California Sgional Water Quality Con*1 Board <br /> Central Valley Region <br /> Karl E. Longley,SCD, P.E.,Chair <br /> Linda S.Adams Arnold <br /> Secretary far 1685E Street,Fresno,Cal(559)445 5910 Schwarzenegger <br /> Environmental (559)445-5116• Pax{5S9}445-5910 Governor <br /> Prronm on http,//www.waterboards.ca.gov/centralvalley <br /> 25 September 2008 ho-, Vvl-E <br /> SEP 2 9 2008 <br /> ENVIRONMENT HEALTH <br /> M. Scott Mansholt PERMIT/SERWICES <br /> Chevron Environmental Management Company <br /> 6111 Bollinger Canyon Road <br /> Rm 3432 <br /> San Ramon, CA 94583 <br /> NO FURTHER ACTION REQUIRED, MOUNTAIN HOUSE DEVELOPMENT SITE #1, BYRON <br /> ROAD, MOUNTAIN HOUSE <br /> Chevron Environmental Management Company (Chevron) submitted a request for No Further <br /> Action Required (NFAR) determination for Mountain House Development Site #1 (Site). The <br /> NFAR, dated 4 January 2008, was prepared by Science Applications International <br /> Corporation (SAIC) on behalf of Chevron. In addition, an Environmental Risk Screening <br /> Evaluation, dated 16 January 2007 (ERE, amended May 2007), prepared by SAIC was <br /> previously submitted. The Site is located near the intersection of Mountain House Road and <br /> West Byron Road, northwest of Tracy, in western San Joaquin County. <br /> Central Valley Regional Water Quality Control Board (Central Valley Water Board) staff has <br /> reviewed the NFAR and ERE reports and our comments are incorporated into the attached <br /> memorandum. <br /> In a 14 June 2007 letter, Central Valley Water Board staff concurred that soil and groundwater <br /> affected by crude oil leaks from Chevron's historical pipelines had been adequately delineated <br /> and additional characterization was not needed. There are no monitoring wells to be <br /> destroyed. <br /> According to the findings, affected soil and groundwater is limited in extent within an area of <br /> approximately 150 by 200 feet in the Byron Road right-of-way (ROW), the Union Pacific <br /> Railroad (UPRR) ROW, and beneath two active refined petroleum product pipelines. The <br /> future use and site access is anticipated to be limited to construction/maintenance activities <br /> associated with the roads and/or the utilities. According to the January 2007 ERE, and <br /> considering that the Site use is not anticipated to change, SAIC conducted the risk evaluation. <br /> The evaluation was based on the most likely potential exposure of a construction/trench <br /> maintenance worker associated with features within the road/railroad/utility corridor. Based on <br /> the risk evaluation, SAIC concluded that the residual crude oil remaining at the site does not <br /> pose a threat to human health for the construction/trench worker scenario. <br /> California Environmental Protection Agency . <br /> 041 Recycled Paper <br />