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• Aontrol BoardCahforn�a Re onal Water Quality Central Valley Region _ <br /> Robert Schneider,Chair Arnold <br /> Linda S.Adams Schwarzenegger <br /> Secretaryfor Fresno Branch Office <br /> Environmental 1685 E Street,Fresno,California 93706 Governor <br /> Protection 16•Fax(559)445-5910 <br /> bttp://www.waterboards,ea.goV/CeDtralvalley FR EC E E D <br /> 23 October 2006 OCT 2 4 2006 <br /> M. Scott Mansholt ENVIRONMENT HEALTH <br /> Chevron Environmental Management Company PERMITISERVICES <br /> 6001 Bollinger Canyon Road, Rm K2066 <br /> San Ramon, California 94583-2324 <br /> ADDENDUM TO ADDITIONAL SITE CHARACTERIZATION WORKPLAN— MOUNTAIN <br /> HOUSE DEVELOPMENT SITE #3, MOUNTAIN HOUSE, SAN JOAQUIN COUNTY <br /> Regional Water Board staff has reviewed the referenced report, dated 6 October 2006 for the <br /> Chevron Old Valley Pipeline (OVP) project. The property is located at the southeast <br /> intersection of Byron Road and Mountain House Parkway, northwest of the City of Tracy. <br /> Currently, the site and surrounding area is agricultural land under development to residential <br /> and/or commercial properties. <br /> Previously, Regional Water Board staff approved a site investigation workplan in a letter to <br /> Chevron dated 27 October 2005. Chevron's consultant, Science Applications International <br /> Corporation (SAIC) in a 10 November 2005 letter, stated that due to wet ground conditions, <br /> the field work would not be completed until 2006. Subsequent to the earlier workplan <br /> approval, Chevron determined that the former Tidewater Associate Oil Company (TAOC) <br /> pipeline(s) was present east of Byron Road, near existing refined product pipelines. <br /> Consequently, the previously approved workplan was amended to incorporate borings to <br /> investigate potential downgradient impacts from the former TAOC pipeline in addition to the <br /> borings for evaluating the OVP (located west of Byron Road). <br /> The amended workplan proposes the following: <br /> • Obtain samples from two domestic water supply wells located within 2,000 feet of the <br /> site; analyze the samples for petroleum constituents and total dissolved solids (TDS); <br /> • Advance three upgradient borings (west of Byron Road) and five downgradient borings <br /> (east of Byron Road) to evaluate soil conditions and collect groundwater samples for <br /> analysis of the petroleum constituents of concern; <br /> • Select and submit a representative soil or groundwater sample for fuel fingerprint <br /> analysis to evaluate if the petroleum hydrocarbons present at the site are historical San <br /> Joaquin Valley crude oil, bunker fuel or from an undetermined source; <br /> • Obtain a groundwater sample from the general area of soil boring MI-13-2, which <br /> previously reported 500,000ug/l TPH as diesel in groundwater; and, <br /> California Environmental Protection Agency <br /> Cal Recycled Paper <br />