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•,��� California Regional Water Quality Control Board .7•. ' <br /> Central Valley Region <br /> Karl E. Longley, Scl), P.E.,Chair <br /> Linda S.Adams Arnold ' <br /> Sucrerarvfor 1685 H 5ituat,5-51 6-I' ,C€flitb ra 45937Ub Schwarzenegger <br /> fr,vrronrqurual (039)4d5-5 i 16•I'tr•�c(559)X45-5910 (Imerrfor <br /> Yrnfec!!aq <br /> http:it�vvr.4rffterbc�rd5.ca.gorcentrAlvallcy ' <br /> 171 F I L <br /> RECEIVED <br /> 12 November 2008 NOV 17 <br /> 2006 <br /> M. Scott Mansholt C0evronEnnonmenlalManagdamentCo. <br /> Chevron Environmental Management Company <br /> 6111 Bollinger Canyon Road <br /> Room 3432 <br /> San Ramon, CA 94583 ' <br /> REVIEW - SOIL AND GROUNDWATER INVESTIGATION REPORT AND ADDITIONAL <br /> INVESTIGATION WORKPLAN, MOUNTAIN HOUSE DEVELOPMENT SITE #6, MOUNTAIN <br /> HOUSE, SAN JOAQUIN COUNTY <br /> Chevron Environmental Management Company (Chevron) submitted a Soil and Groundwater , <br /> Investigation Report with an Additional Investigation Workplan (Workplan) dated 24 July 2008, <br /> for Mountain House Development Site #6 (Site). The Report and Workplan were prepared for <br /> Chevron by Science Applications International Corporation (SAIC). The Site is at the , <br /> intersection of West Byron Road and Wickfund Road, northwest of Tracy. Fallowing <br /> completion of the recent investigation, SAIC proposed that an additional soil and groundwater <br /> investigation be conducted. Detailed comments are provided in the attached memorandum ' <br /> and summarized below. <br /> The Site lies within the West Byron Road and Union Pacific Railroad (UPRR) right-of-way <br /> easements. The historical Old Valley Pipeline (OVP) is parallel, west of West Byron Road and ' <br /> the former Tidewater Associated Oil Company (TAOC) pipeline is between the road and the <br /> railroad tracks. Previously, a workplan dated 31 July 2007, to investigate the lateral and <br /> vertical extent of impacted soil and groundwater onsite and offsite to the east was approved. ' <br /> In March and April 2008, SAIC advanced borings and obtained samples for analysis to <br /> delineate crude oil affected soil and groundwater previously identified at the Site. According to ' <br /> the report, affected soil and groundwater was identified at three separate areas, designated <br /> Area 1, 2, and 3. <br /> SAIC's Report concluded: ' <br /> • The lateral and vertical extent of affected groundwater has been defined in Area 1. The ' <br /> downgradient extent of affected soil has not been defined and an additional <br /> investigation is needed. <br /> • Within Area 2, the lateral extent of soil and groundwater has not been defined and ' <br /> additional investigation is needed downgradient to the east-northeast. <br /> • The lateral, downgradient extent of affected soil to the east-northeast in Area 3 is ' <br /> undefined and additional investigation is needed. <br /> California Environmental Protection Agene-j' ' <br /> Recle led Paper <br />