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A duplicate groundwater sample was collected from well MW-I OA and was labeled MW-DUP. Duplicate groundwater test results are presented along with the primary data in Table 2. Comparison of the primary and duplicate sample results, when both results are measurable concentrations above the practical quantitation limit (PQL) indicates good agreement (within 10%), except for aluminum, iron, and selenium. Review of sampling dates and laboratory analytical certificates indicates that all of the laboratory analyses were completed within required holding times. Based on the results of the laboratory QA/QC analyses, it is concluded that generally acceptable QA/QC procedures were exercised and the water quality samples collected from the French Camp Landfill appear to be 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 south with an average hydraulic gradient of 0.003 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 0.003 sec- fi V = [(0.014 —)*—]- 2835 0.340 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�0.003 for the site during the monitoring period. n,=Effective porosity(n,=0.35);an estimated value. The groundwater flow rate is calculated to be 0.340 feet/day(124 feet/year). 4.4 DETECTION MONITORING PROGRAM Field and laboratory results for DMP monitoring wells (MW-6A, MW-7A, MW-8A, MW-9A, MW-9B, and MW-I OA) from the current monitoring period 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 D:\2008-0012TC_2SA09.doc 3 Geologic Associates