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oe�ftt01D <br /> GAVIN NEWSOM <br /> GOVERNOR <br /> Ca I co R M IA JARED <br /> SECRETARRY FORNFELD <br /> Water Boards ENVIRONMENTAL PROTECTION <br /> Central Valley Regional Water Quality Control Board <br /> 28 October 2021 <br /> Andrew Richle <br /> Water Plant Superintendent <br /> City of Lodi <br /> 2001 W. Turner Road <br /> Lodi, CA 95242 <br /> CONCURRENCE WITH SOIL VAPOR SAMPLING WORK PLAN, CITY OF LODI <br /> SOUTHERN PLUME, LODI, SAN JOAQUIN COUNTY <br /> Central Valley Regional Water Quality Control Board (Central Valley Water Board) staff <br /> reviewed the 13 October 2021 Soil Vapor Sampling Work Plan (Work Plan) prepared by <br /> Civil Hydro Tech (CHT) on behalf of the City of Lodi (City) for the Lodi Southern Plume <br /> (LSP) in Lodi. CHT prepared the Work Plan pursuant to our 21 July 2021 letter for review <br /> of the 17 June 2021 Results of Additional Passive Soil Gas Sampling report. The purpose <br /> of the Work Plan is to assess tetrachloroethene (PCE) and trichloroethene (TICE) in deeper <br /> soil vapor at locations where the highest concentrations were found in shallow soil vapor <br /> during previous investigations. <br /> CHT will perform discrete depth soil vapor sampling to delineate the vertical extent of the <br /> PCE and TICE in soil vapor south of the City's industrial pump station at the LSP-SV1 and <br /> LSP-SV2 locations on Figures 3 and 4 of the Work Plan. CHT will begin by advancing soil <br /> borings to a depth of 50 feet below ground surface (bgs) using continuous soil coring. The <br /> soil cores will be used to log the soil and determine the screen intervals for temporary soil <br /> vapor probe depths. CHT will then install temporary soil vapor sample probes using a <br /> dual-purpose limited access rig. At each soil vapor sampling location, the drill rig will <br /> advance rods to a total depth of 10 feet bgs for installation of 5 and 10 foot soil vapor <br /> probes, and then drill separate borings for installing soil vapor probes at depths of 20, 30, <br /> and 50 feet bgs. <br /> CHT will collect soil vapor samples from each probe in 1-liter Summa canisters using <br /> helium as the leak detection compound. The soil vapor samples will be delivered to a <br /> California-certified laboratory for testing of chlorinated volatile organic compounds by EPA <br /> method TO-15 and helium by EPA method TO-3. CHT will abandon the temporarily well <br /> points upon completion of sampling activities by removing temporary well points and <br /> sealing the borehole with a neat cement grout or by using the appropriate method <br /> approved by the San Joaquin Department of Environmental Health. CHT will prepare a <br /> report documenting the soil vapor sampling activities, summarizing the results, and that will <br /> KARL E. LONGLEY SCD, P.E., CHAIR I PATRICK PULUPA, ESQ., EXECUTIVE OFFICER <br /> 11020 Sun Center Drive#200, Rancho Cordova, CA 95670 1 www.waterboards.ca.gov/centralvalley <br />