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QA/QC procedures were exercised. The water quality samples collected from the French Camp Landfill appear to be generally representative of water quality at the site. 4.3 GROUNDWATER ELEVATIONS AND CONTOURS Prior to purging and sampling, each well was sounded for water depth using a weighted electronic sounder, and the static water level was recorded on a Well Data Sheet (Appendix Q. The groundwater elevations were calculated for each well by subtracting the depth-to-water measurement from the top-of-casing reference elevation. The current and historical groundwater elevation data for the French Camp Landfill is summarized in Table 5. The groundwater elevation data obtained during the monitoring period were used to generate the groundwater elevation contour maps shown on Figures I A and I B, which indicates that groundwater generally flows to the southeast with an average hydraulic gradient of 0.002 ft/ft. To calculate the approximate linear groundwater flow velocity for the site, conservative assumptions were used, including a hydraulic conductivity of 0.014 cm/sec, and an estimated effective porosity of 35 percent(CH2M Hill 2000). An estimated range in groundwater flow velocity was calculated using Darcy's Law: Ki CM 0.002 sec- ft V _ [(0.014 —)* —]* 2835 0.227 ft/day ne sec 0.35 cm - day where: V=Groundwater flow velocity. K=Hydraulic conductivity of the water-bearing unit(0.014 cm/sec). i=Hydraulic gradient: i�0.002 for the site during the monitoring period. n,=Effective porosity(n,=0.35);an estimated value. The groundwater flow rate is calculated to be 0.227 feet/day(83 feet/year). 4.4 DETECTION MONITORING PROGRAM Field and laboratory results from the current monitoring period for DMP monitoring wells (MW-6A, MW-7A, MW-8A,MW-9A, MW-913, and MW-1 OA) are summarized in Table 2 and time-series plots are presented in Appendix D. As shown in the time-series plots, general chemistry and metals constituent concentrations are generally consistent with historical concentrations. However, constituent concentrations of bicarbonate, calcium, chloride, magnesium,nitrate as nitrogen, specific conductance, sulfate, and total dissolved solids (TDS)measured in the samples collected from wells MW-I OA and/or MW-9A have exhibited decreasing concentrations since 2010. During the monitoring period, chloroform and trichlorofluoromethane (TCF ) were measured above the PQL in the samples collected from wells MW-6A and MW-9A, respectively, and a notification letter was sent to the RWQCB of these VOC detections C:\zou-oosnFc_zsnu.aoe 3 Geo-Logic Associates