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Eov xunn0.BRow„JR. <br /> uAn�..R poRlauez <br /> Water Boards <br /> Central Valley Regional Water Quality Control Board <br /> 27 April 2012 <br /> Mr. Joe Niland <br /> Lincoln Center Environmental Trust <br /> c/o Geosyntec Consultants <br /> 3043 Gold Canal Drive, Suite 201 <br /> Rancho Cordova, CA 95670 <br /> COMMENTS ON WORK PLAN FOR ADDITIONAL SOIL-GAS SAMPLING FOR CLOSURE <br /> OF SVE INTERIM REMEDIAL ACTION—LINCOLN CENTER, SAN JOAQUIN COUNTY <br /> The Central Valley Regional Water Quality Control Board (Central Valley Water Board) has <br /> reviewed the report titled "Excavation Implementation and Post Excavation Sampling Report" <br /> (Report) prepared by Arcadis on behalf of Lincoln Center Environmental Remediation Trust <br /> (Trust) dated 12 March 2012. <br /> The following actions have been completed in support of the Trust's proposal to terminate <br /> operation of the air/ozone sparging and soil vapor extraction interim remedial action (IRA) <br /> systems: <br /> • In 2009, the Trust proposed to shut-off the soil vapor extraction (Phase 2 IRA) <br /> and the air/ozone sparging systems (Phase 4 IRA) in the Site's source area and <br /> conduct a rebound study. <br /> • In January 2010, the Trust collected baseline soil-gas samples at 10 approved <br /> locations onsite. <br /> • In February 2010, the Trust shut down the system to allow the subsurface to <br /> equilibrate and return to static conditions. <br /> • In May 2010, the Trust collected confirmation samples from the same 10 <br /> locations to analyze rebound in the source area. <br /> • In August 2010, the Trust proposed closure of the air/ozone sparging and SVE <br /> system based on the results of the confirmation samples. <br /> • In January 2011, Central Valley Water Board staff issued a letter stating that the <br /> confirmation data does not support a decision to permanently decommission the <br /> remediation systems. The letter further stated that the Trust should collect <br /> additional confirmation samples approximately 12 months from the date of the <br /> letter. Based on the results of the additional confirmation samples, Central <br /> Valley Water Board staff would re-assess soil and groundwater conditions at the <br /> Site. <br /> • In February 2012, the Trust submitted a work plan to collect the additional <br /> confirmation samples from the same locations using identical techniques as the <br /> previous sampling event in support of closure of the air/ozone sparging and SVE <br /> systems. <br /> KARL E. LONGLEY SOD. P.E..CRAM I PAMELA Q CREEOON.EREOOT.E OiFlCER <br /> 11020 Sun Cenler Orlve N200.RancNa Cordova.CA 9E070 1 www.weterbgartle.ca.gov/centralvalley <br /> 4i .uvca[v rnven <br />