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EDMUND D.BPOWp JP. <br /> Q Ea.A-�- fto EI <br /> MAnNEw RooewDaz <br /> • Water Boards <br /> Central Valley Regional Water Quality Control Board <br /> 3 November 2014 <br /> Chevron Environmental Management Company <br /> and Phillips 66 (L&M Group) <br /> c/o Dan Schreiner <br /> Stantec Consulting Services Inc. <br /> 3017 Kilgore Road, Suite 100 <br /> Rancho Cordova, CA 95670 <br /> WORK PLAN FOR ADDITIONAL SOIL VAPOR SURVEY, L&M OPERABLE UNIT, STOCKTON, <br /> SAN JOAQUIN COUNTY <br /> Central Valley Water Board staff has reviewed the 30 May 2014 Work Plan for Additional Soil Vapor <br /> Survey(work plan) and the 30 May 2014 Remediation System Removal Proposal prepared by <br /> Stantec Consulting Services Inc. on behalf of Chevron Environmental Management Company and <br /> Phillips 66 (L&M Group) for the L&M Operable Unit site in San Joaquin County. These documents <br /> • were submitted pursuant to Central Valley Water Board staff's 7 April 2014 letter that requested them <br /> following a meeting held on 7 March 2014. <br /> The Work Plan proposes to install seven new off-site soil vapor sampling probes (APSV-11 through <br /> APSV-17) and two new onsite probes (UPSV-7 and UPSV-8) at locations shown on Figure 2 of the <br /> work plan. The purpose of the additional probes is to verify that the source area has been sufficiently <br /> remediated such that additional soil vapor extraction (SVE) or other remedial actions for the source <br /> area are not necessary related to human health considerations. As discussed on 7 March 2014, the <br /> L&M Group is also proposing to remove the SVE/DPE remedial equipment, but to leave the wells, <br /> piping, gas and electrical connections, and manifolds in place to allow for possible future use. The <br /> work plan includes in its Attachment 1, a copy of the 17 January 2014 Vapor Intrusion Contingency <br /> Plan (contingency plan). We understand based on our discussions in the recent 23 October 2014 <br /> meeting that the proposals in the contingency plan will be updated and be part of the report <br /> presenting the results of the additional soil vapor survey. <br /> Central Valley Water Board staff concurs with the work plan for the additional soil vapor survey and <br /> with the proposal to remove the SVE/DPE remedial equipment. Please submit a results report for the <br /> additional soil vapor survey by 1 April 2015. In addition to the results of the soil vapor survey, the <br /> report shall include the proposed monitoring/reporting schedule and constituents for the soil vapor <br /> probes, any necessary modifications to the previously submitted contingency plan (including the <br /> appropriate screening levels), and information about how and when SVE will be restarted in the future <br /> if proposed soil vapor concentration screening levels are exceeded in specified probes. As <br /> discussed, we will expect to meet with you again sometime prior to the 1 April 2015 deadline to further <br /> discuss what will be in the plan. <br /> KARL E. LONOLEY SCD, P.E., CHAIR I PAMELA C. CREEDON P.E., BCEE, EXECUTIVE OFFICER <br /> 11020 Bun Center Drive NEW,Rancho Cordova.CA 95670 1 www.waterb rds.u.gov/Centr.lv.1i.y <br /> 0 RECYCLED PAPER <br />