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Vinyl Chloride. Trend analysis will continue to be used quarterly to evaluate concentrations of VOCs in MW-5. LFG is believed to be the source of VOCs at this well. MW-8(Impacted): Concentrations of all parameters were within established concentration limits where the limits could be determined (Table 1). Based on output from the Sanitas statistical software, an increasing trend is reported in Bicarbonate Alkalinity, whereas a decreasing trend is reported in the concentration of Chloride, and Sulfate(Table 3). One primary MCL for Nitrate as Nitrogen was slightly exceeded in MW-8 this quarter. No secondary MCLs were exceeded in MW-8 this quarter. Seven VOCs were reported this quarter,three above"trace" concentration, one (Tetrachloroethene) above their MCLs (Table 1). All VOCs detected in this well are among the VOCs found in MW-5, generally at lower concentrations. It is our opinion that MW-5 is closer to the source of the VOCs and thus has more VOCs. Trend analysis of VOC concentrations indicates increasing trends for Tetrachloroethene and Trichloroethene. Trend analysis will continue to be used quarterly to evaluate concentrations of VOCs in MW-8. Deep Aquifer 31W-6(Down gradient): Concentrations of all parameters were within established concentration limits where the limits could be determined (Table 2). No primary MCLs were exceeded this quarter in MW-6. Secondary MCLs for EC, TDS, and Sulfate were exceeded in MW-6 this quarter. However,the EC, TDS and Sulfate levels are consistent with the general historical conditions at this well. Based on output from the Sanitas statistical software, a decreasing trend is reported in the concentration of Nitrate as Nitrogen this quarter(Table 3). No VOCs were reported at this well this quarter. Other than false positives,no VOCs have been reported since Toluene was reported in 2005 when the well was first installed. These Toluene data indicate that this compound was probably introduced by the drilling company when this well was installed in 2003,but quickly reduced to "trace.' in three quarters. Excluding probable contamination during well construction and compounds also found the QC blanks,no VOC has been reported in this well. Therefore,there has been no indication of impact from the landfill at this well. MW-7(Up gradient): Concentrations of all parameters were within established concentration limits where the limits could be determined (Table 2). A comparison of general water quality parameters between MW-7 (up-gradient) and MW-6 (downgradient)indicates better water quality downgradient of Corral Hollow Sanitary Landfill. Department of Public Works/Solid Waste 1 s'Quarter 2012 Groundwater Monitoring County of San Joaquin—April 16,2012