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• i EDMUND G. BROWN JR. <br /> wwrA MnerRV`ORDaiouaz <br /> Water Boards `ViRDN eN.°`RR°"°"DN <br /> Central Valley Regional Water Quality Control Board <br /> TO: Duncan Austin, P.E. FROM: Steven Meeks, P.E. <br /> Program Manager Chief, PriM27 nit <br /> Site and Groundwater Cleanup <br /> SIGNATURE: <br /> DATE: 5 August 2014 <br /> SUBJECT: SOURCE AREA SOILS NO FURTHER ACTION;LINCOLN VILLAGE SHOPPING <br /> CENTER <br /> Rationale <br /> Soil vapor data indicates that the soil vapor extraction (SVE) system has effectively removed <br /> tetrachloroethene (PCE) from the vadose zone soil in the onsite source area at the Lincoln <br /> Village Shopping Center in Stockton, California (Site). <br /> In September 2012, Central Valley Regional Water Quality Control Board (Central Valley Water <br /> Board) staff requested that the Lincoln Center Environmental Remediation Trust (Trust) conduct <br /> a PCE source area-focused SVE system optimization test in historically high concentration <br /> source areas, followed by a round of confirmation samples to ensure that the SVE system had <br /> reached its effective removal limit. <br /> With our concurrence, Geosyntec Consultants, Inc. conducted (on behalf of the Trust) the SVE <br /> system optimization measures (system pulsing) and confirmation soil sampling activities <br /> between November 2012 and February 2013, and summarized its findings in the Soil Closure <br /> Report(Report) dated 1 May 2013. The Report documented the additional SVE system <br /> optimization testing and soil vapor data collection activities; presented laboratory analytical <br /> results; evaluated the data with respect to SVE system optimization; and requested a No <br /> Further Action (NFA) determination from the Central Valley Water Board for onsite source area <br /> soils. In a letter dated 2 August 2013, Central Valley Water Board staff stated that the most <br /> recent soil vapor contained in the Report indicated that the PCE concentration levels are below <br /> the California Human Health Screening Levels (CHHSLs) for commercial use of the property. A <br /> few of the soil vapor data points exceeded CHHSLs for residential use of the property. <br /> However, the concentrations of PCE in those small, limited areas will continue to dissipate and <br /> would not be expected to cause excessive health risks even if the property were eventually <br /> converted to residential use. As such, staff do not believe that a land use covenant or deed <br /> restriction is necessary for this Site. <br /> KARL E. LONGEV SCD, P.E., CHAIR I PAMELA C. CREEDON P.E., BCEE, EXECUTIVE OFFICER <br /> 11020 Sun Center Drlve#200,Rancho Cordova,CA 95670 1 WWW.Waterboards.ca.9ov/centralva1ley <br /> C"aemmeD FAIIN <br />