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SB-I(Up gradient): Concentrations of all the parameters analyzed were within established concentration limits this quarter except for Bicarbonate Alkalinity(Table 1). However, because there are no primary and secondary MCLs for Bicarbonate Alkalinity, this exceedance does not pose a human health risk. No primary MCLs were exceeded this quarter in SB-1. Secondary MCL for TDS was exceeded in SB-1 this quarter. However, the TDS levels are consistent with the general historical conditions at this well. A"significantly decreasing"trend is reported by the Sanitas program for sulfate this quarter, and a"significant increasing"trend is reported for EC, 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. No VOCs were reported at SB-1 this quarter. A trace concentration of one VOC was reported in this well in the 4h Quarter 2011. With this one exception, VOCs have not been reported in this well since second quarter 2004 when trace concentrations of one VOC was reported. MW-4(Down gradient): Concentrations of all the parameters analyzed were within established concentration limits this quarter except for Bicarbonate Alkalinity(Table 1). However, because there are no primary and secondary MCLs for Bicarbonate Alkalinity, this exceedance does not pose a human health risk. Ask No primary MCLs were exceeded this quarter in W-4. Secondary MCLs for EC, Sulfate, and TDS were also exceeded in M -4 this quarter. However,the EC, Sulfate, and TDS levels are consistent with the general historical conditions at this well. Sanitas statistical analysis indicates decreasing trends in Bicarbonate Alkalinity, and Sulfate this quarter(Table 3). These trends were first apparent during the following quarters: • Sulfate in first quarter 2005 • Bicarbonate in second quarter 2012 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, increasing trends are reported in Nitrate and TDS,whereas decreasing trends are reported in the concentration of Sulfate(Table 3). One primary MCL for Nitrate as Nitrogen was slightly exceeded in MW-5 this quarter. Secondary MCLs for EC, and TDS were also exceeded in MW-5 this quarter. Corral Hollow Sanitary Landfill 1 Department of Public Works/Solid Waste 2nd Quarter 2012 Groundwater Monitoring County of San Joaquin—July 30,2012