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Water Quality Monitoring Report <br /> French Camp Landfill <br /> sample results indicates that with the exception of TDS, there was good agreement with a <br /> relative percent difference (RPD) of less than seven percent when both results are measurable <br /> concentrations above the practical quantitation limit (PQL). For TDS, the RPD was 17 percent. <br /> Review of sampling dates and laboratory analytical certificates indicates that all of the <br /> laboratory analyses were completed within required holding times. Based on the results of the <br /> laboratory QA/QC analyses, it is concluded that acceptable QA/QC procedures were exercised, <br /> and the water quality samples collected from the French Camp Landfill appear to be <br /> representative of water quality at the site. <br /> 4.3 Groundwater Elevations and Contours <br /> Prior to purging and sampling, each well was sounded for water depth using a weighted <br /> electronic sounder, and the static water level was recorded on a Well Data Sheet (Appendix Q. <br /> The groundwater elevations were calculated for each well by subtracting the depth-to-water <br /> measurement from the top-of-casing reference elevation. The current and historical <br /> groundwater elevation data for the French Camp Landfill is summarized in Table 5. <br /> The groundwater elevation data obtained during the monitoring period were used to generate <br /> the groundwater elevation contour maps shown on Figures 1 and 2, which indicates that <br /> groundwater generally flows in an easterly direction, converging near wells MW-9A and MW-9B <br /> with hydraulic gradients ranging between 0.001 ft/ft and 0.004 ft/ft. <br /> To calculate the approximate linear groundwater flow velocity for the site, conservative <br /> assumptions were used, including a hydraulic conductivity of 0.014 cm/sec, and an estimated <br /> effective porosity of 35 percent (CH2M Hill, 2000). The estimated groundwater flow velocity <br /> was calculated using Darcy's Law: <br /> Ki cm 0.004 sec— ft <br /> V = —_ [(0.014 —)* ]*2835 0.45 ft /day <br /> ne sec 0.35 cm —day <br /> where: V= Groundwater flow velocity. <br /> K= Hydraulic conductivity of the water-bearing unit (0.014 cm/sec). <br /> i = Maximum hydraulic gradient: i & 0.004 for the site during the monitoring <br /> period. <br /> ne= Effective porosity (ne= 0.35); an estimated value. <br /> The groundwater flow rate is calculated to be 0.45 feet/day(166 feet/year). <br /> Is <br /> Project No.2014.0012 FC 2SA14 Report.docx 3 <br /> 1/20/2015,Rev.0 <br />