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Two VOCs were reported in MW-2 this quarter. No VOCs were reported in the other wells. No parameters were found in any of the Quality Control Blanks this quarter. MW-1 Up-gradient) No general water quality parameters were exceeded in MW-1 this quarter. However, there is a statistically significant increasing trend in EC. As stated in previous reports (beginning with the fourth quarter 2004), the cause of the trend is believed to be other than the landfill because this well is up-gradient. Trend analysis also notes an increasing trend in TDS this quarter at this well. The increasing trend in TDS is also related to the trend in EC. Because of these trends in the landfill's upgradient well, increasing levels of EC and TDS in the downgradient wells should be expected. No VOCs were reported in MW-1 this quarter. MW-2 MW-2 is an impacted well. No general water quality parameters were exceeded in MW-2 this quarter. A statistically significant increasing Chloride trend continue this quarter. However, the Chloride concentration this well (24 mg/L) is far below the secondary maximum contaminant level of 250 mg/1. Trend analysis indicates an increasing trend for Turbidity this quarter. However, it is unlikely that the increasing tend in turbidity is a result of landfill activities. The increase in turbidity could be due to siltation within the well. This trend will be monitored in future reports to determine if action is necessary. Two VOCs, Tetrachloroethene(PCE), and Dichlorodifluoromethane were reported this quarter. These compounds are those historically impacting this well. 1,2 Dichloropropane was not reported this quarter. This compound has been reported in the last eleven monitoring events. Trend Analysis indicates that there is an increasing trend for PCE this quarter. However, the detected concentration(1.8 ug/L)has not exceeded the maximum concentration limit(MCL) of 5.0 ug/L. Although there is no MCL for Dichlorodifluoromethane, EPA Region 9 has developed Preliminary Remediation Goal (PRG) for Dichlorodifluoromethane of 390 ug/L, which is two orders of magnitude greater than the concentration detected. The vacuum at landfill gas wells in the vicinity of this well has been increased to reverse this trend. Harney Lane Sanitary Landfill Department of Public Works/Solid Waste 2nd Quarter 2007 Groundwater Monitoring Report County of San Joaquin—July 15,2007 5