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.� California Regional Water Quality Control Board _ <br /> Central Valley Region t <br /> Robert Schneider,Chair <br /> Alan C.Lloyd,Ph.D. Arnold <br /> Secretaryjor Fresno Branch Office Schwarcenegger <br /> Environmental 1685 E Street,Fresno,California 93706 Governor <br /> Protection (559)445-5116•Fax(559)445-5910 <br /> http:l/www.waterboards.ca.gov/centralvalley <br /> 14 July 2005 JUL 1 5 2005 <br /> ENVIRONMENT HEALTH <br /> M. Scott Mansholt PERMIT/SERVICES <br /> Chevron Environmental Management Company <br /> 6001 Bollinger Canyon Road <br /> Rm.K2066 <br /> San Ramon, CA 94583-2324 <br /> REVIEW OF SOIL AND GROUNDWATER INVESTIGATION, MOUNTAIN HOUSE SITE #2, <br /> MOUNTAIN HOUSE, SAN JOAQUIN COUNTY <br /> I have reviewed the 15 May 2005 Soil and Groundwater Investigation Report, Mountain House Site #2, <br /> Mountain House, San Joaquin County, prepared for ChevronTexaco by Science Applications International <br /> Corporation (SAIL). The site is within an approximately 300-foot long section of the former Old Valley <br /> Pipeline (OVP) right-of-way adjacent to Byron Road and 200-feet northwest of the Mountain House Creek <br /> crossing. The OVP previously transported crude oil and Bunker C fuel oil between Kern County oil fields <br /> and refineries in the Richmond area until the 1970's. <br /> Additionally, we reviewed a 26 November 2001 soil and groundwater investigation completed for <br /> Trimark Communities, Inc. by Condor Earth Technologies. The Condor investigation identified separate <br /> locations along the former OVP, including the subject site that had been impacted by leaks from the <br /> OVP. At the Mountain House Site#2, TPH as crude oil (TPH-c) concentrations ranging from 11 mg/kg <br /> to 12,000 mg/kg was reported in three borings between 16 and 20 feet. Groundwater was encountered <br /> between 7 and 17 feet, but was not sampled. <br /> The current report describes the installation of eight temporary borings and collection of soil and <br /> groundwater samples for laboratory analysis. The purpose of the investigation was to characterize the <br /> lateral and vertical extent of total petroleum hydrocarbon (TPH)-impacted soil and groundwater in the <br /> vicinity of Condor borings GP-9, GP-174, and GP-175. <br /> In addition to analysis of samples for delineation purposes, soil and groundwater samples were analyzed <br /> for the TPH constituents of concern (TPH as diesel [TPH-d], polynuclear aromatic hydrocarbons <br /> [PAHs], and BTEX, i.e. benzene, toluene, ethylbenzene, and xylenes) to support a future Human Health <br /> Risk Assessment (HHRA). Soil samples for HHRA purposes were obtained from a depth of two feet <br /> and six feet; lateral and vertical characterization samples were obtained at depths of 20 to 44 feet. <br /> California Environmental Protection Agency <br /> �a Recycled Paper <br />