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MW-2 (Impacted): No general water quality parameter concentration limits were exceeded in MW-2 during the first or second semester 2013 sampling events. Three VOCs (Benzene, Toluene, and PCE) were detected in MW-2 at a trace concentration during the first semester sampling on February 1, 2013. Benzene, Toluene and PCE were also detected in trace concentrations in resampling on March 1, 2013. One VOC (PCE)was detected in MW-2 at a trace concentration during the second semester 2013 sampling event conducted on August 2, 2013. VOCs will continue to be checked for at this well during the next semiannual event. Historically, the impact to groundwater at MW-2 has been believed to be due to landfill gas, as indicated by the presence of the following VOCs: • CFC-12 (last reported second semester 2007) • 1,2-Dichloropropane (last reported in 2006) • PCE (last reported second semester 2012) CFC-12 and 1,2-Dichlopropane were not detected in MW-2 during this year. PCE was detected in concentrations below 1 ppb. The reduction of impact indicates significant reduction in impact by VOCs at MW-2. The trend analysis by Sanitas software indicates increasing trends for Turbidity, and TDS, and a decreasing trend for Chloride during the first and second semester 2013 Sampling Events. The EC concentration in this well (349.3 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. MW-3: Concentrations of all the parameters analyzed were within established concentration limits during the first semester except for Turbidity (Table 1). The trend analysis by Sanitas software indicates increasing trends for Turbidity, TDS, and a decreasing trend for Chloride, and Sulfate during the first semester 2013 sampling event. One VOC (Dichlorodifluoromethane) was detected in MW-3 at trace concentrations during the first semester 2013 sampling event conducted on February 1, 2013. Dichlorodifluoromethane was also detected at trace concentrations in MW-3 during the resampling event conducted on March 1, 2013. The consistent detection of VOCs in this well is unusual. The presence of VOCs in this well be securitized during the next routine monitoring event. Well MW-3 replaced by MW-3A in June 2013 due to falling groundwater levels. MW-3A will no Harney Lane Sanitary Landfill 11 Department of Public Works/Solid Waste 2"d Semester and Annual 2013 Groundwater Monitoring Report County of San Joaquin—January 31,2014