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RESULTS Quarterly monitoring results show that the landfill's final cover and LFG system are preventing further degradation of the groundwater. Three VOCs were reported in the first and third quarters tof 2006 in MW-2, the impacted well. These are the same compounds reported in previous analyses. The total number of VOCs reported in groundwater in MW-2 is not increasing and the concentrations reported are either traces or just above the practical quantitative limit. No VOCs were reported in wells MW-1, MW-3 and W-4 this quarter. No VOCs have been reported in either down-gradient well MW-3 or well W-4 for 26 consecutive quarters. No VOCs were reported in up-gradient well MW-1 the past five quarters. The County anticipates a continued reduction in the VOCs in groundwater at monitoring well MW-2 as a result of the reduction of leachate and LFG (and associated VOCs) in the vadose zone. A statistically significant upward trend in Chloride concentration in impacted well MW-2 was indicated for the past year; however, the concentration has been decreasing the past seven quarters. Increasing trends are also present for Chloride in MW-3 and MW-4. This data may represent a change in the background groundwater quality in the region. PROPOSED INCREASE IN CORRECTIVE ACTION Although it appears that corrective action at MW-2 is successful, that is, groundwater quality is not degraded further, we are not satisfied with the progress of the corrective action. Therefore, we propose to increase corrective action against the VOC impact by installing at least two gas extraction wells, designed to collect gas from the soil beneath the landfill, in the general vicinity of MW-2 (Figure I-1). This would be the first step in a program of gradually increasing corrective action at this site. Additional wells would be added as needed,possibly each year, depending on the quarterly groundwater monitoring results. It is our understanding from our consultant that this general approach has been effective at at least one other site. Harney Lane Sanitary Landfill 1-4 Department of Public Works/Solid Waste 1"Quarter 2007 Groundwater Monitoring Report County of San Joaquin—April 15,2007