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French Camp Landfill, located within the central Stockton area, has been impacted by saltwater intrusion and the elevated chloride and TDS concentrations measured in well MW-l0A are believed to be the result of this condition and not the result of landfill- related impacts. 4.5 LEACHATE MONITORING The laboratory results for leachate monitoring well MW-2 are summarized in Table 3 and time-series concentration plots are presented in Appendix D. As shown on Table 3, no VOCs were detected in leachate monitoring well MW-2 during the monitoring period. As previously discussed in section 4.2,the VOCs detected in the duplicate sample are believed to be the result of a mix up with another site that was sampled on the same day. 4.6 SURFACE-WATER MONITORING Field and laboratory results for surface-water monitoring stations (SW-1, SW-2, and SW-3) for the current monitoring period are summarized in Table 4. Stations SW-1 and SW-2 are located upstream of the landfill within the Walker and French Camp Sloughs, respectively, and are used as background sampling points, while station SW-3 is located downstream of the landfill at the confluence of the two sloughs. Water quality data from surface-water sampling stations were graphed on time-series concentration plots and are presented in Appendix D. For the surface-water monitoring stations at the French Camp Landfill, CLs are used for the WQPS. Since CLs are not provided in the WDRs,the CLs shown in Table 4 were calculated by Herst&Associates using Sanitas®, a state-approved statistical software program using historical data from background surface-water stations SW-1 and SW-2, and are presented in Appendix D. As shown in Table 4, no CLs were exceeded and no VOCs were detected in the samples collected from the surface-water stations during the monitoring period. A comparison of upgradient(SW-1 and SW-2)to downgradient(SW-3) surface-water samples indicates generally similar inorganic constituent concentrations in the upgradient and downgradient surface-water stations, suggesting that the landfill is not impacting surface water quality. Only carbonate at surface-water station SW-1 and field turbidity at all three surface-water stations exhibited statistically significant increasing trends (Appendix D). As noted above, surface-water stations SW-1 and SW-2 are background surface-water monitoring points and increasing trends in the surface-water quality at these points are not indicative of an impact from the facility. Given that turbidity exhibits a statistically significant increasing trend at background surface-water points SW-1 and SW-2,the increasing trend in turbidity at SW-3 is unlikely to be indicative of an impact from the landfill. Stream gauging was performed on August 18 and 19, and December 2, 2010 at monitoring points SG-1 and SG-2 and the data is summarized in Table 5. As shown in Figure 1, monitoring point SG-1 is located upgradient in the Walker Slough and monitoring point SG-2 is located upgradient in the French Camp Slough. D:\201"030\FC_25A 10.d oc 5