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EOMUNo G. BROWN JR. <br /> GOVERNOR <br /> 3T• <br /> C A L I F O P N I A MATTHEW RooRlouEz <br /> Water Boards S«R[IARv FOR <br /> t l:vi__ENTAL PROTECTION <br /> Central Valley Regional Water- Quality Control; Board <br /> 31 January 2017 <br /> �1 <br /> Bonny Carter & 1 <br /> Director of Facilities and Planning �N��Rr�h,tr�Nr <br /> Tracy Unified School District P�R�%r/SFS NEA <br /> 1875 W. Lowell Avenue <br /> Tracy, CA 95376 <br /> RE: REMEDIAL ACTION PLAN, DELTA ISLAND SCHOOL, 11022 WEST HOWARD ROAD, <br /> STOCKTON, CALIFORNIA <br /> Dear Ms. Carter. <br /> Central Valley Regional Water Quality Control Board (Central Valley Water Board) staff have <br /> reviewed the Remedial Action Plan (RAP) dated 12 October 2016 and prepared by GHD <br /> Services Inc. for the former Delta Island School property located at 11022 West Howard Road in <br /> Stockton, California (Site). The objective of the RAP is to address actions needed to remove <br /> the residual oil impacts in soil that originated from a power transformer at the site. <br /> Remedial Action Plan Evaluation <br /> Previous investigations have determined that residual Total Petroleum Hydrocarbon as Diesel <br /> (TPH-d) exists in the shallow soil directly beneath and in close proximity to the former <br /> transformer pad. The RAP examined three alternatives to address TPH-d in the shallow soil at <br /> the site: 1) no action, 2) selective source area excavation, and 3) extensive excavation. <br /> Extensive excavation was selected as the proposed alternative based on the ability to achieve <br /> the overall site goal of returning the property to pre-release conditions. <br /> Proposed Scope of Work <br /> The RAP proposes to remove TPH-d impacted soil via excavation. Heavy equipment will be <br /> used to remove the hydrocarbon impacted soil from 7 to 10 ft bgs within the previously <br /> assessed area around the former transformer pad. Former investigative information and field <br /> evidence will be used to determine the final extents of the excavation, including soil screening <br /> using a photoionization detector (PID), and visual evidence due to discoloration or the presence <br /> of oil. <br /> Soil removed from outside the targeted removal area due to the need to slope the excavation <br /> sidewalls will be segregated from a hydrocarbon impacted stockpile, inspected and scanned <br /> with a PID for hydrocarbon impact. If no impacts are observed, the segregated materials will be <br /> placed onto and covered with plastic. Once the excavation is complete, a 4-point composite <br /> sample will be collected from the non-impacted stockpile and analyzed for TPH-d. If no <br /> concentrations are reported in the composited sample, this material will be used as backfill <br /> KARL E. LONGLEY SCD, P.E., CHAIR PAMELA C. CREEDON P.E., BCEE, EXECUTIVE OFFICER <br /> 11020 Sun Center Drive#200,Rancho Cordova,CA 95670 1 www.waterboards.ca.gov/centralvalley <br /> C?RECYCLED PAPER <br />