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LFR Inc. <br /> extraction well network, installed in the area of the Site downgradient from Lincoln <br /> Center (wells GWE-18 through GWE-33). <br /> • Phase IV implemented in 2007: Operation of air and ozone sparging at 59 wells <br /> (AS-1 through AS-59; Figure 4) within the Historical Source Area at Lincoln <br /> Center <br /> • Phase V implemented in 2008: Injection of emulsified soybean oil to induce an <br /> enhanced reductive zone in the vicinity of the Bank of Stockton east and <br /> hydraulically downgradient from Lincoln Center. <br /> Since its installation, the GWETS (Phase I and III IRAs) has effectively mitigated <br /> downgradient migration of Hazardous Substances in both A- and B-zone groundwater at <br /> Lincoln Center and will remain operational. The GWETS continues to remove volatile <br /> organic compound (VOC; Hazardous Substances) mass, thereby meeting the objective <br /> of the Phase I and III IRAs. Operation and compliance data for the GWETS are <br /> reported semiannually in accordance with National Pollutant Discharge Elimination <br /> System (NPDES) permit requirements (e.g., LFR 2009). <br /> Phase V has been shown to be effective at remediating higher concentrations of <br /> Hazardous Substances present within A-zone groundwater in the area hydraulically <br /> downgradient from Pacific Avenue(Figure 2). This is a passive system that will <br /> continue to be monitored for effectiveness. <br /> 1.2 Phase II IRA (SVETS) <br /> The SVETS was started up in October 1999 in accordance with the "Phase II Interim <br /> Remedial Action Detailed Plan," dated May 14, 1999 (LFR 1999). SVETS <br /> performance has been monitored using field instruments and through the collection of <br /> samples for laboratory analyses from SVE wells and soil-vapor monitoring wells. The <br /> SVETS influent and effluent is monitored weekly using a photoionization detector(PID) <br /> in accordance with San Joaquin Valley Air Pollution Control District air discharge <br /> requirements. <br /> The Phase II IRA (SVETS) has effectively reduced concentrations of Hazardous <br /> Substances in source area vadose-zone soils and within indoor air at Lincoln Center. <br /> Since start-up in 1999 through June 2009, the SVETS has removed a total of <br /> approximately 7,500 pounds of PCE from soil vapor. <br /> Over the past 10 years of active operation of the SVETS, concentrations of Hazardous <br /> Substances have decreased significantly in the wells within the treatment area. <br /> Historical analytical results for samples collected from SVE wells and soil-vapor <br /> monitoring wells are summarized in Table 1. PCE isoconcentration contour drawings <br /> for sampling events conducted between 1999 and 2005 are depicted on Figures 5 <br /> through 12. <br /> Pfte 2 plao-Imm-Phil IV IRA-Aug09.06750.dm:deh <br />