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MW-1 (Up-gradient) dient) The concentration of EC was higher g than the established concentration limit this quarter. There is also 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 the well is up-gradient. Trend analysis also notes an increasing trend in total dissolved solids this quarter. No VOCs were reported in MW-1. MW-2 MW-2 is an impacted well. A statistically significant increasing Chloride trend continues, the Chloride concentration exceeded the tolerance limit,however, it is well below the recommended secondary maximum contaminant level for drinking water, 250 mg/l. 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. Three VOCs, Tetrachloroethene(PCE), 1,2-Dichloropropane, and Dichlorodifluoromethane were reported this quarter. Trend analysis indicates an increasing trend for both 1,2-Dichloropropane and Tetrachloroethene (PCE)this quarter. Adjustments to the operation of the landfill gas collection system may be necessary to reverse the upward trend of VOC impact. Increased vacuum may need to be placed on the refuse to control landfill gas in the portion of the landfill adjacent to well MW-2. MW-3 The concentration of EC was higher than the established concentration limit this quarter. An increasing trend in Chloride continues this quarter; however, Chloride concentrations are generally lower in the past eight quarters. Because this fluctuation also occurs in the upgradient well, we believe that changes in groundwater quality are due to natural fluctuation of groundwater quality in the region. This was noted in previous reports (beginning with the second quarter 2004) and continues at the present. An increasing trend in turbidity was also noted this quarter. However, we expect the presently- indicated increasing trend in turbidity to return to no-trend status. Note: the drinking water standard for turbidity is a secondary standard(an aesthetic water standard). Harney Lane Sanitary Landfill Department of Public Works/Solid Waste 4t"Quarter and Annual 2006 Groundwater Monitoring Report County of San Joaquin—January 15,2007