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Water Quality Monitoring Report French Camp Landfill 4.4.1 Concentration Limits For DMP monitoring wells at the French Camp Landfill, concentration limits (CLs) provided in WDR R5-2007-0046 are used for the water quality protection standards (WQPS). All CLs are provided in Table 2 for comparison with current monitoring data. The following table presents constituents that were found to exceed a CL: CONSTITUENT CONCENTRATION DMP MONITORING WELLS LIMIT MW-6A* MW-7A* MW-8A MW-9A I MW-9B MW-10A GENERAL CHEMISTRY(mg/L) Chloride 249in 310ME NOTES: (*)—Background Well. A shaded cell indicates that the current value was measured below the CL. Only constituents that exceeded a CL are provided in the table above. All CLs are provided in Table 2. Previously, a No Release Demonstration (NRD) was performed for CL exceedances of chloride and TDS at the site (Herst, 2005). The NRD concluded that French Camp Landfill, located within the central Stockton area, has been impacted by saltwater intrusion and the elevated chloride and TDS concentrations measured in groundwater monitoring wells are believed to be the result of this condition and not the result of landfill-related impacts. 4.4.2 Non-Statistical Data Analysis The non-statistical VOC water analyses were performed on the DMP well data collected during the monitoring period. Non-statistical exceedances were identified at wells MW-6A and MW-9A. These exceedances are the result of quantifiable concentrations of chloroform and trichlorofluoromethane (TCFM) measured in well MW-6 and MW-9A, respectively. Confirmation sampling was not performed since these compounds have already been confirmed in each respective well. Given the distance of well MW-6A from the landfill (approximately 0.25 miles upgradient),the chloroform concentrations measured in well MW-6A are not believed to be the result of a release from the landfill, while the TCFM concentration measured in well MW-9A has been attributed to the placement of the final cover system on the landfill and continues to exhibit decreasing concentrations. In order to evaluate changes in water quality in DMP wells at the French Camp Landfill, Sen's Slope trend analyses were performed for those constituents exceeding a CL. During the monitoring period, no statistically significant increasing temporal trends were calculated for constituents exceeding a CL and current concentrations measured in these wells within the historical range of values for these wells. A statistically significant decreasing trend was calculated for TCFM concentrations at well MW-9A. Trend analyses are presented in Appendix D. Project No.2016.0007 4