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quarter 1994 and repeated detections of 1, 2-Dichloropropane appeared after first quarter 1996. <br /> The County believes that the presence of VOCs in groundwater collected from MW-2 was due to <br /> landfill gas. <br /> A landfill gas collection system was installed in 1996 and has been operated to mitigate <br /> groundwater impact and to control off-site migration of landfill gas. <br /> The sporadic and low level detection of the following three chlorinated VOCs have been used as <br /> indication of groundwater impact by landfill gas: <br /> • CFC-12 (last reported fourth quarter 2007) <br /> • 1, 2-Dichloropropane (last reported 2006) <br /> • PCE <br /> Low levels of Toluene, a fuel-related VOC, are occasionally detected in some samples. <br /> COMPLIANCE EVALUATION SUMMARY <br /> Monitoring Program <br /> Water quality was monitored consistent with WDR Order No. R5-2009-0049. <br /> Groundwater <br /> ® The groundwater well network consists of up-gradient well MW-1 and down-gradient wells MW-2, <br /> MW-3, and MW-4 (Figure 2). MW-5 and MW-6 were installed in 2010. Well MW-5 is <br /> hydraulically upgradient of the Secondary Site portion of facility and hydraulically side gradient of <br /> the Primary Site 1 portion of the facility (Figures 2 and 3). Well MW-6 is hydraulically upgradient <br /> of all past landfilling operations at the site. All wells are equipped with dedicated purge and <br /> sampling pumps. All wells are surveyed based on the NAVD88 control rather than MSL. The <br /> purpose of wells MW-6 and -6 were to assess potential impact by the wastewater treatment <br /> ponds at the migrant labor housing facility, which are located immediately up-gradient of the <br /> Secondary site. <br /> Groundwater at MW-2 was previously impacted. <br /> Groundwater samples are analyzed for the following semiannual monitoring and field parameters <br /> as specified in WDR Order No. R5-2009-0049: <br /> Temperature Total Dissolved Solids (TDS) <br /> pH Chloride <br /> Turbidity Electrical Conductivity (EC) <br /> Dissolved Oxygen (DO) Total Alkalinity <br /> Redox potential Total Hardness <br /> Volatile Organic Compounds (VOCs) Chemical Oxygen Demand <br /> Harney Lane Sanitary Landfill 2 Department of Public Works/Solid Waste <br /> I"Semester 2013 Groundwater Monitoring Report County of San Joaquin—July 15,2013 <br />