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A landfill gas collection system was installed in 1996 and has been operated to mitigate groundwater impact and to control off-site migration of landfill gas. The sporadic and low level detection of the following three chlorinated VOCs have been used as indication of groundwater impact by landfill gas: • CFC-12 (last reported fourth quarter 2007) • 1, 2-Dichloropropane (last reported 2006) • PCE Low levels of Toluene, a fuel related VOC, is occasionally detected in some samples. COMPLIANCE EVALUATION SUMMARY Monitoring Program Water quality was monitored consistent with WDR Order No. R5-2009-0049. Groundwater The groundwater well network consists of up-gradient well MW-1 and down-gradient wells MW-2, MW-3, and MW-4 (Figure 2). Two new wells have been recently installed, MW-5 and MW-6. Well MW-5 is hydraulically upgradient of the Secondary Site portion of facility and hydraulically side gradient of the Primary Site 1 portion of the facility (Figures 2 and 3). Well MW-6 is hydraulically upgradient of all past landfilling operations at the site. All wells are equipped with dedicated purge and sampling pumps. All wells are surveyed based on the NAVD88 control rather than MSL. Groundwater at MW-2 was previously impacted. Groundwater samples are analyzed for the following semiannual monitoring and field parameters as specified in WDR Order No. R5-2009-0049: Temperature Total Dissolved Solids (TDS) pH Chloride Turbidity Electrical Conductivity (EC) Dissolved Oxygen (DO) Total Alkalinity Redox potential Total Hardness Volatile Organic Compounds (VOCs) Chemical Oxygen Demand Groundwater samples are analyzed annually for the following additional parameters: • Sulfates • Bicarbonate Alkalinity • Nitrate— Nitrogen • Chloride Harney Lane Sanitary Landfill 2 Department of Public Works/Solid Waste 1"Semester 2012 Groundwater Monitoring Report County of San Joaquin—July 31,2012