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'l <br />MONITORING SULTS <br />Groundwater <br />Summary <br />' Groundwater was sampled on October 17, 2013. <br />No VOCs were reported in the deep aquifer wells. No VOCs were reported in shallow aquifer <br />wells SB -1, MW -4, and MW -9A this quarter. Data from the shallow aquifer wells beyond the <br />County property seems to support a tentative conclusion that the quality of the water in this <br />aquifer appears to be improving. <br />Shallow Aquifer <br />Summary <br />Conditions in the shallow aquifer appear to be improving incrementally. <br />No general water quality parameters were exceeded in any wells this quarter. <br />Seven VOCs were detected in impacted on-site well MW -5 and five VOCs were detected in <br />impacted on-site well MW -8. Concentrations of VOCs at well MW -5 appear to be decreasing <br />over the past year (see discussion below). <br />No VOCs were detected in new off-site monitoring well MW -9A this quarter or for the last three <br />quarters. Three VOCs were detected in new off-site monitoring well MW -10A, and three VOCs <br />were detected in new off-site monitoring well W -1 1A. All VOCs detected in these wells are <br />among the VOCs found in MW -5 and MW -8, generally at lower concentrations. <br />Data from MW -1 IA is encouraging. Only three VOCs were reported, this quarter, compared to <br />six compounds when the well was first installed. This indicates an improvement in water quality <br />at this well. The County will review with interest succeeding monitoring data to assess whether <br />we are seeing the start of a trend. <br />L The source of these VOCs is apparently from LFG emanating from the refuse discovered near the <br />County/Caltrans property boundary line, where the influence of the LFG system has been <br />minimal. . Landfill Gas System Information is provided in Appendix H. <br />SB-1(Up gradient): <br />Concentrations of all the parameters analyzed were within established concentration limits this <br />quarter (Table 1). <br />Corral Hollow Sanitary Landfill 12 Department of Public Works/Solid Waste <br />4`" Quarter and Annual 2013 Groundwater Monitoring County of San Joaquin — January 15, 2014 <br />