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® This is a significant improvement since 2007, when all three compounds were consistently reported at well MW-2. With the exception of Turbidity in MW-2, MW-3, W-4 and EC in MW-2 no concentration limits, where concentration limits could be determined, were exceeded in any wells during the second semester 2012 sampling event. MW-1 (Up-gradient) No general water quality parameter concentration limits were exceeded during the second semester 2012 sampling event. No VOCs were detected in MW-1 during the second semester 2012 sampling event The trend analysis by Sanitas software indicates increasing trends for EC and Chloride, and a decreasing trend for Turbidity during the second semester quarter 2012. However, MW-1 is the upgradient well. The increasing trends in EC and Chloride could be from changes in background water quality conditions. MW-2 Concentrations of all the parameters analyzed were within established concentration limits this semester except for EC and Turbidity (Table 1). One VOC (PCE) was detected in MW-2 at a trace concentration during the second semester 2012 sampling event conducted on July 30, 2012. ® Historically, the impact to groundwater at MW-2 was apparently due to landfill gas, as indicated by the presence of the following VOCs: • CFC-12 (last reported fourth quarter 2007) • 1,2-Dichloropro pane (last reported in 2006) • PCE CFC-12 and 1,2-Dichloropropane were not detected in MW-2 during this sampling event and these VOCs were not detected in MW-2 in the sixteen previous quarters. The lack of these compounds indicates removal of these VOCs from the groundwater at MW-2. Therefore, landfill gas extraction apparently has been successful in reducing or removing the VOC impact near this well. The trend analysis by Sanitas software indicates increasing trends for Turbidity, TDS, and a decreasing trend for Chloride during the second semester 2012 sampling event. The EC concentration in this well (360 mg/L) is far below the secondary maximum contaminant level (MCL) of 900 uS/cm, and indicates good water quality. TDS has also not exceeded their secondary MCL standards, which address aesthetics rather than human health issues. It is unlikely that the increasing trend in turbidity is a result of landfill activities. Siltation within the well is often the cause of an increase in turbidity that does not affect the water quality of the aquifer outside of the well. As such, turbidity is an indicator of well function and not an indicator of landfill impact to groundwater. Harney Lane Sanitary Landfill 6 Department of Public Works/Solid Waste 2nd Semester and Annual 2012 Groundwater Monitoring Report County of San Joaquin—January 25,2013