ARCHIVED REPORTS_2012_8 - Laserfiche WebLink

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® MW-4(Down gradient): Concentrations of all the parameters analyzed were within established concentration limits this quarter(Table 1). A"significantly decreasing"trend is reported by the Sanitas program for chloride, sulfate and TDS this quarter(Table 3). However,the variation in concentrations are slight, so the reports of "significant trend" appears to be an artifact of the Sanitas statistical calculations. This indicates the continuation of a relatively long trend of improving general water quality conditions at this well. It is likely that the improvements to the drainage ditch in 2003 resulted in these improvements in general water quality at MW-4. No VOCs were reported at this well this quarter. Other than compounds also reported in quality control blanks, VOCs have not been reported in this well since third quarter 2001. MW-5(Impacted): Concentrations of all the parameters analyzed were within established concentration limits this quarter(Table 1). Based on output from the Sanitas statistical software, an increasing trend is reported in TDS,whereas decreasing trends are reported in Turbidity and Sulfate (Table 3). Six VOCs were reported in impacted well MW-5: four above "trace" concentrations (Table 1). These data are consistent with previous monitoring results. Trend analysis of VOC concentrations indicates increasing trends for 1,1-Dichloroethane and PCE, and a decreasing trend for Dichlorodifluoromethane, Trichloroethene, and Vinyl Chloride. Trend analysis will continue to be used quarterly to evaluate concentrations of VOCs in MW-5. 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 trends are reported in Bicarbonate Alkalinity and Total Alkalinity as CaCO3, whereas a decreasing trend is reported in the concentration of Chloride,Nitrate as Nitrogen, Turbidity, and Sulfate (Table 3). These data are consistent with previous monitoring results.. Five VOCs were reported this quarter,three above "trace" concentrations (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 1,1-Dichloroethane, Dichlorodifluoromethane,PCE and Trichlorofluoromethane. Trend analysis will continue to be used quarterly to evaluate concentrations of VOCs in MW-8. Corral Hollow Sanitary Landfill Department of Public Works/Solid Waste 3`d Quarter 2012 Groundwater Monitoring County of San Joaquin—October 30,2012