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Water Quality Monitoring Report <br /> French Camp Landfill <br /> 4.6 Surface Water Monitoring <br /> Field and laboratory results for surface water monitoring stations (SW-1, SW-2, and SW-3) for <br /> the current monitoring period are summarized in Table 4 and time-series concentration plots <br /> are presented in Appendix D. Stations SW-1 and SW-2 are located upstream of the landfill <br /> within the Walker and French Camp Sloughs (respectively) and are used as background <br /> sampling points. Station SW-3 is located downstream of the landfill at the confluence of the <br /> two sloughs. A comparison of upgradient (SW-1 and SW-2) to downgradient (SW-3) surface <br /> water samples indicates generally similar inorganic constituent concentrations. Three VOCs <br /> (bromodichloromethane, chloroform, and dibromochloromethane) were detected in samples <br /> from upgradient surface water monitoring station SW-2 (all at trace concentrations) and <br /> downgradient station SW-3 (two quantifiable concentrations and one trace concentration). <br /> These particular VOCs are drinking water disinfection byproducts (trihalomethanes) that likely <br /> originate from a source other than the landfill. No other VOCs were detected in samples <br /> collected from surface water monitoring stations. In a letter dated June 26, 2015, the RWQCB <br /> was notified of the non-statistical exceedances. Verification retesting is currently scheduled for <br /> July 2015. <br /> Stream gauging was performed on March 2 and May 20, 2015, at monitoring points SG-1 and <br /> SG-2 and the data are summarized in Table 5. As shown in Figures 1 and 2, monitoring point <br /> SG-1 is located upgradient in the Walker Slough and monitoring point SG-2 is located <br /> upgradient in the French Camp Slough. <br /> 5.0 SOIL-PORE GAS MONITORING <br /> In accordance with WDR Order No. 115-2007-0046, perimeter soil-pore gas probes are <br /> monitored using a field screening protocol, and soil-pore gas samples are only collected if field <br /> screening indicates methane concentrations greater than 2.5 percent. During the monitoring <br /> period,field screening of soil-pore gas probes was conducted on March 30, 2015. As shown on <br /> Table 6, methane was only detected in one of the soil-pore gas probes at a low concentration of <br /> 0.1 percent by volume. As a result, no samples were collected. <br /> Project No.2015.0014 5 <br />