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A duplicate groundwater sample was collected from well MW-7A 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 PQL, indicates good agreement (within 6%). Review of the semiannual 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 the laboratory data generated for the current monitoring period are generally acceptable 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 C). 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 1 and 2. During the first quarter 2010 (Figure IA) groundwater flowed to the northeast with an average hydraulic gradient of 0.003 ft/ft. During the second quarter 2010 (Figure 1B) groundwater flowed to the southeast with an average hydraulic gradient of 0.001 ft/ft. To calculate the approximate linear groundwater flow velocity for the site, conservative assumptions were used, including a hydraulic conductivity of 300 gallons per day per square foot(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– ft V _ — _ [(0.014 —)* ]*2835 0.34 ft /day ne sec 0.35 cm – day where: V=Groundwater flow-velocity- K= elocity.K=Hydraulic conductivity of the water-bearing unit(0.014 cm/sec). i=Maximum hydraulic gradient:i-0.003 for the site during the monitoring period. ne=Effective porosity(ne=0.35);an estimated value. The groundwater flow rate is calculated to be 0.34 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-lOA) 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 DA2010-0030TC 1SAIO.doc 3 GeoLogic Associates