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Water Quality Monitoring Report ® French Camp Landfill 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 and time-series concentration plots are presented in Appendix D. 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. Station SW-3 is located downstream of the landfill at the confluence of the two sloughs. A comparison of upgradient (S -1 and SW-2) to downgradient (SW-3) surface water samples indicates generally similar inorganic constituent concentrations. No VOCs were detected in surface water samples during the monitoring period. Stream gauging was performed on August 10 and October 27, 2017, at monitoring points SG-1 and SG-2 and the data are summarized in Table 5. As shown in Figures 1 and 2, 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. 115-2007-0046, perimeter soil-pore gas probes are monitored 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 September 30 and December ® 11, 2017. As shown on Table 6, methane was only detected in one of the soil-pore gas probes (SGP-7A) at a concentration of 0.1 percent by volume during the fourth quarter 2017. As a result, no samples were collected. 6.0 ANNUAL SUMMARY 6.1 General During the 2017 monitoring year, groundwater elevation measurements were performed quarterly and water quality sampling and soil-pore gas monitoring were performed semiannually in accordance with WDR Order No. 115-2007-0046. All of the monitoring points were sampled for the monitoring parameters summarized in Table 1. A tabular summary of the historical monitoring data is presented in Appendix C and time-series plots depicting groundwater and surface water constituent concentrations are presented in Appendix D. Stiff diagrams of the semiannual data obtained in 2017, hydrographs illustrating the historical groundwater elevations of the detection monitoring wells, and information relative to well screen elevations and pump intake elevations are also included in Appendix D. 6.2 Groundwater Over the 2017 monitoring year, groundwater elevations varied up to eight feet with hydraulic gradients ranging between 0.002 ft/ft to 0.003 ft/ft to the east. Groundwater quality conditions beneath the French Camp Landfill during the 2017 monitoring year are generally Project No.5017.1030 5