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a <br /> Californiaogional Water Quality Conol Board <br /> Central Valley Region <br /> Karl E.Longley,ScD,P.E.,Chair a <br /> Linda S.Adams Sacramento Main Office Arnold <br /> EnvSecironmentetaryforal <br /> 11020 Sun Center Drive#200,Rancho Cordova,California 95670.6114 Sch Governor Environmental Phone(916)464-3291 •FAX(916)4644645 Governor <br /> Protection http://www.waterboards.cagov/centralvalley <br /> 21 March 2007 <br /> Ben Hall <br /> Musco Family Olive Company <br /> 17950 Via Nicolo <br /> Tracy, California 95376 <br /> REVIEW AND RESPONSE TO BACKGROUND GROUNDWATER QUALITY ASSESSMENT <br /> WORK PLAN, MUSCO FAMILY OLIVE COMPANY, TRACY, SAN JOAQUIN COUNTY <br /> The Regional Water Quality Control Board (Regional Water Board) staff has reviewed the <br /> Background Groundwater Quality Assessment Work Plan dated 27 February 2007. The work <br /> plan was prepared in response to the Regional Water Board staffs 15 December 2006 <br /> Review of Groundwater Quality and Hydrogeology(Memo) of the Musco site. Based on the <br /> available data, staff made recommendations with the focus on developing background <br /> groundwater concentrations, installing groundwater monitoring wells to further characterize <br /> groundwater impacts both in the shallow and deep water bearing zones beneath the site, and <br /> installing additional groundwater monitoring wells offsite of the Musco facility. <br /> In a meeting on 12 January 2007 between Musco and Regional Water Board staff, Musco <br /> proposed to proceed with the recommendations in a phased approach that included: <br /> 1. Installing one shallow and one deep background groundwater wells in the vicinity of the <br /> Hansen Well to develop background groundwater concentrations, <br /> 2. Installing replacement wells for MW-6, MW-9, MW-10, and MW-13, and <br /> 3. Installing three additional wells south, southwest, and southeast of Field 95. <br /> a <br /> Once the Phase I wells are installed and groundwater sampling initiated, Musco will submit a <br /> second work plan to install the "Phase 11" wells. Regional Water Board staff agrees with the <br /> phased approach and Musco may proceed with scheduling the proposed scope of work with <br /> the following conditions: <br /> Background groundwater concentrations must be developed only from the Phase I <br /> wells located within the mid-fan and distal fan facies of the alluvial fan environment <br /> outside of the impact zone (offsite). Staff has identified this area as being located in <br /> the vicinity of the Hansen Well. These Phase I well locations are shown on Figure 3 of <br /> the Work Plan, identified as A(R2)/B(R3). <br /> California Environmental Protection Agency <br /> co,Recycled Paper <br />