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California Regional Water Quality Control Board <br /> ` Central 'Valley Region , <br /> Karl C. Longley,ScD, PE,Chair ,�•".�" <br /> Linda S.Adams Arnold ' <br /> Secrernryfor Fresno Branch Office Schwarzenegger <br /> Envrrownewal 1685 I:51ree1,Fresno,California 93706 <br /> Proreclron (559)445-5116•Fax(559)445-5910 Governor <br /> hitp://t1ikiv.kvalerboards.ca.gov/ccnlraIvaIley ' <br /> 31 July 2007 ' <br /> M. Scott Mansholt <br /> Chevron Environmental Management Company ' <br /> 6001 Bollinger Canyon Road <br /> Rm K2066 <br /> San Ramon, CA 94583-2324 ' <br /> REVIEW OF REVISED SOIL AND GROUNDWATER WORKPLAN, MOUNTAIN HOUSE <br /> SITE #6, WICKLUND ROAD AT W. BYRON ROAD, MOUNTAIN HOUSE, SAN JOAQUIN ' <br /> COUNTY <br /> Regional Water Board staff has reviewed the referenced workplan, dated 13 July 2007 and <br /> submitted by Science Applications International Corporation (SAIC) on behalf of Chevron. <br /> The project is in the community of Mountain House on West Byron Road, approximately 700- <br /> feet northwest of Wicklund Road. Regional Water Board staff approved SAIC's original , <br /> project workplan on 13 April 2005; an amended SAIC workplan requesting removal of methyl <br /> tertiary butyl ether (MTBE) from the analytical suite was approved on 6 March 2006. <br /> According to our files, the initial discovery of petroleum hydrocarbons in soil was confirmed <br /> attributable to leaks from the Old Valley Pipeline (OVP) and/or the Tidewater Associated Oil <br /> Company (TAOC) pipelines that had existed on the site. Mountain House Site #6 <br /> encompasses an approximate length of 1,000 feet and at this time as much as 200-feet wide. <br /> Two refined products pipelines (Kinder Morgan Energy Partners and Bay Area Products Line) <br /> are located within the former OVPITAOC right-of-way corridor. The Union Pacific Railroad <br /> right-of-way (ROW) runs along the eastern property boundary. <br /> During an investigation by Condor Earth Technologies, Inc. (Condor) in 2001 , crude oil- ' <br /> affected soil and groundwater were encountered. Condor's investigation indicated elevated <br /> concentrations of petroleum hydrocarbons present in at least six soil borings. Total petroleum ' <br /> hydrocarbons as crude oil (TPHc) in soil was encountered at depths of 4.5 to 20-feet with <br /> TPHc concentrations reported as high as 29,000 mg/kg. <br /> Total petroleum hydrocarbons as diesel (TPHd) was reported in groundwater samples at <br /> concentrations as high as 260,000 micrograms per liter (pg/L); TPH as gasoline (TPHg) was <br /> reported as high as 9,900 pg/L; BTEX compounds were ND. Depth to groundwater is ' <br /> between 7 and 17-feet. <br /> California Environmental Protection Ageucy <br /> �pw fZecf c•lecl l'<rper ' <br />