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on December 1, 2011. Confirmation sampling was not performed for background well <br /> MW-6A since similar concentrations of chloroform have already been confirmed and <br /> based on the lack of chloroform at the point of compliance, it is believed that the <br /> chloroform concentrations measured in well MW-6A are not the result of a release from <br /> the landfill. A retest sample was collected from well MW-9A on December 2, 2011 and <br /> TCFM was confirmed in the retest sample. As presented in the March 12, 2007 letter the <br /> RWQCB no further action is necessary since the TCFM concentration measured in well <br /> MW-9A is well below risk-based concentrations. <br /> Concentration Limits <br /> For DMP monitoring wells at the French Camp Landfill, concentration limits (CLs) <br /> provided in the WDRs are used for the water quality protection standards (WQPS). <br /> Based on a comparison of the data obtained during the current monitoring period, only <br /> the chloride concentration measured in well MW-913 (320 mg/L) exceeded its <br /> concentration limit of 249 mg/L. As shown in the time-series plots (Appendix D), the <br /> current chloride concentration measured in well MW-913 is near the historical minimum <br /> value measured at this well. <br /> Trend Analysis <br /> In order to evaluate changes in water quality in DMP wells at the French Camp Landfill, <br /> historical groundwater data were evaluated using Sen's Slope trend analyses to determine <br /> if statistically significant increasing or decreasing trends were evident. Trend analyses, <br /> performed by Herst & Associates, are presented in Appendix D and summarized below. <br /> Well Number Increasing Trends Decreasing Trends <br /> MW-6A None Apparent Calcium,Magnesium,pH <br /> MW-7A None Apparent Chloride, Specific Conductance,TDS <br /> MW-8A None Apparent Bicarbonate,Calcium, Chloride,Magnesium, <br /> Nitrate-N,TDS <br /> MW-9A None Apparent Nitrate-N,TCFM <br /> MW-9B Potassium, Sulfate pH <br /> MW-10A Chloride Nitrate-N <br /> During the monitoring period, statistically significant increasing trends were calculated <br /> for potassium and sulfate in well MW-913, and for chloride in well MW-10A. However, <br /> none of these constituents exceeded a CL. One or more statistically significant <br /> decreasing trends were calculated, for inorganic constituent concentrations, in all of the <br /> groundwater monitoring wells at the French Camp Landfill. For organic constituents, a <br /> decreasing trend was calculated for TCFM in well MW-9A. <br /> 4.5 LEACHATE MONITORING <br /> The laboratory results for leachate monitoring well MW-2 are summarized in Table 3 and <br /> time-series concentration plots are presented in Appendix D. As shown on Table 3, no <br /> VOCs were detected in leachate monitoring well MW-2 during the monitoring period. <br /> C:\2011-0051\FC 2SAII.doc 4 Geo-Logic Associates <br />