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t <br /> • Total Organic Carbon <br /> • Inorganics (dissolved) <br /> • VOCs (extended list) <br /> • Semi-Volatile Organic Compounds <br /> • Chlorophenoxy Herbicides <br /> • Organophosphorous Compounds <br /> Leachate samples were last analyzed for COCs during the first semester 2005 monitoring event. <br /> The next monitoring event for leachate COCs will occur during the first semester of 2010. <br /> Vadose Zone Soil Gas <br /> The soil is monitored for VOCs per the WDRs Order No. R5-2003-0020. Eleven wells, SG-1 <br /> through SG-11, are located around modules "I" and 1 (Figure 5). Wells extend from 25 feet to <br /> 68 feet below the surface. Gas from the soil gas trench under Module 1, designated SG-T, is also <br /> analyzed for VOCs. <br /> The Monitoring and Reporting Program requires that soil gas be monitored semi-annually. <br /> Samples are analyzed by a certified laboratory per EPA test method TO-14A. <br /> MONITORING RESULTS <br /> Sampling and analysis procedures are in Appendix A; the field data sheets are in Appendix B. <br /> The laboratory reports are in Appendix C. <br /> 1 Statistical Analysis <br /> The FSL has been approved to use interwell tolerance limits methods, with an upgradient well <br /> providing background data(Table 2). <br /> MW-4 was located directly up-gradient of the landfill based on groundwater elevations from the <br /> previously-installed wells. This well has been sampled four times since installation. Because the <br /> quantity of data from this well is insufficient to establish concentration limits until at least eight <br /> samples are collected, data from MW-1 is used to calculate concentration limits on a provisional <br /> basis. Until sufficient data from MW-4 is available for that analysis, conclusions regarding <br /> possible groundwater impacts from Sanitas software will be tentative, and will be tempered with <br /> review of the data. The County proposes to increase sampling at MW-4 until sufficient data is <br /> available for statistical analysis. <br /> Groundwater <br /> Monitoring and Field Parameters <br /> A review of the first quarter general water quality parameters (Table 2) indicates compliance with <br /> concentration limits that can be validly derived. <br /> Foothill Sanitary Landfill 7 Department of Public Works/Solid Waste <br /> 1"Semester 2009 Groundwater Monitoring County of San Joaquin—July 31,2009 <br />