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Californiallbegional Water Quality Como/ Board ' <br /> Central Valley Region <br /> Karl E. Longley,ScD;P.E.,Chair <br /> Linda S.AdamsArnold <br /> Secrera,yfor 1685 C Street,Fresno,California 93706 � (�� D <br /> U <br /> (559)445-5116•Fax(559)445-5910 [� Schwarzenegger <br /> Envirownental Governor <br /> Protection ht[palwww.waterboards.ca.govlcentra[Val ley <br /> NOV 2008 <br /> 31 October 2008 ENVIRONMENT HEALTH <br /> PER AI TISERVICES <br /> M. Scott Mansholt <br /> Chevron Environmental Management Company <br /> 6111 Bollinger Canyon Road <br /> Rm 3432 <br /> Sart Ramon, CA 94583 <br /> REVIEW— ENVIRONMENTAL RISK EVALUATION, MOUNTAIN HOUSE DEVELOPMENT <br /> SITE #5, MOUNTAIN HOUSE, SAN JOAQUIN COUNTY <br /> On behalf of Chevron Environmental Management Company (Chevron), Science Applications <br /> International Corporation (SAIC) submitted the 15 September 2008 report Environmental Risk <br /> Evaluation (ERE), Mountain House Development Site #5 (Site). The Site is along Byron Road <br /> approximately 2,500 feet northwest of the Mountain House Creek crossing northwest of Tracy, <br /> in western San Joaquin County. Mountain House Development Site #4 is adjacent to and <br /> southeast of Site #5. <br /> The Site lies within the Byron Road right-of-way (ROW) easement, primarily beneath the <br /> Byron Road highway alignment. The ROW easement is approximately 125 feet wide and <br /> includes the historical Old Valley Pipeline (OVP) that lies adjacent the southwest side of Byron <br /> Road. The Union Pacific Railroad (UPRR) ROW, approximately 140 feet wide is adjacent the <br /> northeast side of the highway and includes the historical Tidewater Associated Oil Company <br /> (TAOC) pipelines as well as the UPRR tracks. Two active refined petroleum products lines, <br /> the Bay Area Products Line (BAPL) operated by Chevron Pipeline Company, and the Kinder <br /> Morgan, LLC pipeline, are located within the UPRR easement between the tracks and the <br /> highway. <br /> Central Valley Regional Water Quality Control Board (Central Valley Water Board) staff has <br /> reviewed the ERE report. Additionally, 2001 to 2007 soil and groundwater investigation <br /> reports, prepared for Chevron by SAIC and other environmental consulting firms, were <br /> reviewed. <br /> The initial Site investigation in 2001 identified petroleum hydrocarbon affected soil in one of <br /> five borings at approximately 16 feet below ground surface (bgs). Analysis of the soil sample <br /> from 16 foot bgs detected total petroleum hydrocarbons as crude oil (TPHc), chrysene, <br /> fluorene, and phenanthrene, attributed to leaks from the historical OVP pipeline at <br /> concentrations of 7,600 milligrams per kilogram (mg/kg), 0.2 mg/kg, 0.7 mg/kg, and 1.6 mg/kg, <br /> respectively. Groundwater was not sampled. <br /> SAIC conducted an investigation in latter 2005, advancing eight borings to depths of 32 to <br /> 46 feet bgs. Thirty-one soil samples and five groundwater samples were collected for <br /> California Environmental Protection Agency <br /> 0a Recycled Paper <br />