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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 QPS. Since CLs are not provided in the WDRs,the CLs shown in Table 4 were calculated by Herst& Associates using Sanitas 9, 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 stations SW-1 and SW-3, and field turbidity at all three surface-water stations exhibit statistically significant increasing trends (Appendix D). Given that carbonate and turbidity both exhibit statistically significant increasing trends at background surface-water points SW-1 and/or SW-2, these increasing trends at SW-3 are unlikely to be indicative of an impact from the landfill. Stream gauging was performed on August 30 and 31, and November 7, 2011 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. 5.0 SOIL-PORE GAS MONITORING In accordance with WDR Order No. R5-2007-0046, soil-pore gas probes are monitored semiannually using a field screening protocol, and soil-pore gas samples are only collected if field screening indicates methane concentrations greater than 2.5 percent. During the monitoring period, field screening of soil-pore gas probes was conducted on August 31, 2011. As shown on Table 6, no methane was detected in any of the soil-pore gas probes, and as a result, no samples were collected. C:\2011-0051TC 2SAII.doc 5 Geo-Logic Associates