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California RItional Water Quality Shntrol Board <br /> Central Valley Region <br /> Robert Schneider,Chair <br /> Alan C.Lloyd,Ph.D. Arnold <br /> Agency Secremry Sacramento Main Office Schwarzenegger <br /> 11020 Sun Center Drive#200,Rancho Cordova,California 956706114 Governor <br /> Phone(916)464-3291•FAX(916)4644645 <br /> bttp:llw .waterboards.ca.govlcentralvalley <br /> November 4, 2005 W FECCEV E© <br /> NOV — 9 2005 <br /> Donald Bradshaw, P.G. EWIRONMENT HEALTH <br /> LFR Levine Fricke I'ER1 IT/SERVICES <br /> 1900 Powell Street, 12th Floor <br /> Emeryville, CA 94608 <br /> REVIEW OFRESULTS OFAIR SPARGE PILOT TEST,LINCOLN CENTER, STOC%TON,SAN <br /> JOAQUINCOUNTY <br /> Staff of the Central Valley Regional Water Quality Control Board has reviewed the results of the Air <br /> Sparge Pilot Test Results for Lincoln Center, Stockton (the Site), and your recommendations for <br /> installing and operating a full scale ozone/air sparging system. The document is dated September 15, <br /> 2005 €nd was received by the Central Valley Water Board on September 16, 2005. <br /> Former dry cleaning operations at the Site have resulted in the presence of tetrachloroehtene (PCE) in <br /> soil and groundwater. Investigation activities conducted to date indicate that the existing groundwater <br /> extraction and treatment system(GWETS)has been successful in reducing chlorinated solvent <br /> concentrations, and specifically PCE, in the relatively more permeable A Zone. However, a rise in <br /> groundwater elevation of approximately 15 feet from 1996 to 2000 has created a resaturated zone in low <br /> permeability sediments. The Resaturated Zone is responding more slowly to remedial measures. <br /> Therefore, an Air Sparging Pilot Test (ASPT) was conducted to further evaluate ways to accelerate <br /> remediation in the Resaturated Zone and in the vadose zone sediments located directly above. Together, <br /> these two zones are referred to as the "Historical Source Area." <br /> Based on the data from the ASPT, it appears that air sparging can be successful in reducing the <br /> concentration of PCE, as numerous positive indicators were obtained from the test results. However, <br /> LFR has recommended blending ozone with air for more accelerated destruction of PCE in the Historical <br /> Source Area. Ozone injection is a documented technology for oxidizing PCE and its degradation <br /> products. According to LFR, ozone has been used at several sites similar to Lincoln Center. <br /> Staff concurs with the findings of the ASPT, and we approve the implementation of an air sparging <br /> system. However, we do not approve addition of ozone at this time. Currently, the concentration of <br /> PCE in soil and groundwater is too high to use ozone. Because ozone use results in the complete <br /> destruction of the PCE molecule, and the destruction of one PCE molecule creates four chlorine <br /> complexes, this process will result in the production of unacceptable levels of chloride and total <br /> dissolved solids (TDS) in the aquifer, which could cause unacceptable degradation of water quality for <br /> those compounds. First, air sparging combined with soil vapor extraction (SVE) should be implemented <br /> to lower the concentration of PCE by removal form the vadose zone. Then, ozone can be added to the <br /> California Environmental Protection Agency <br /> 0 Recycled Paper <br />