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During the third quarter 2006 monitoring event,one duplicate sample was collected from <br /> well MW-16 and labeled MW-DUP. As shown on Table 2-2, duplicate sample analysis <br /> yielded good correlation(within 5%)with the primary sample results. <br /> Review of laboratory analysis dates with required holding times indicates that with the <br /> exception of non-volatile organic carbon and chemical oxygen demand analyses for <br /> surface water, all samples were submitted and analyzed within the required holding times <br /> during the third quarter 2006. <br /> Based on the results of the laboratory blank and duplicate analyses, it is concluded that <br /> the laboratory data generated for the third quarter 2006 monitoring period are generally <br /> acceptable. <br /> 2.1.3 Groundwater Elevations and Contours <br /> Prior to purging and sampling, each well was sounded for water depth using a weighted <br /> electronic sounder to an accuracy of 0.01 foot, and the static water level was recorded on <br /> a Well Data Sheet(Appendix Q. The groundwater elevations were calculated for each <br /> well by subtracting the depth-to-water measurement from the top-of-casing reference <br /> elevation. The current groundwater elevation data for the Forward Unit is summarized in <br /> Table 2-3. <br /> The groundwater elevation data obtained during third quarter 2006 monitoring period <br /> were used to generate the groundwater elevation contour map shown on Figure 2-1, <br /> which indicates that groundwater at the site generally flows to the northeast at an average <br /> hydraulic gradient of approximately 0.002 ft/ft. <br /> To calculate the approximate linear groundwater flow velocity for the site, conservative <br /> assumptions were used, including a hydraulic conductivity of 875 gallons per day per <br /> square foot(0.04 cm/sec) and an estimated effective porosity of 35 percent (CH2M Hill <br /> 2000). The estimated maximum groundwater flow velocity was calculated using Darcy's <br /> Law: <br /> Ki cm 0.002 sec– ft <br /> V = —_ [(0.04—)* ]*2835 0.648 ft/day <br /> ne sec 0.35 cm –day <br /> where: V=Groundwater flow velocity. <br /> K=Hydraulic conductivity of the water-bearing unit(0.04 cm/sec). <br /> i=Hydraulic gradient: i%t�0.002 for the site during the third quarter 2006. <br /> ne=Effective porosity(nc=0.35);an estimated value. <br /> The groundwater flow rate is calculated to be 0.648 feet/day(237 feet/year). <br /> 2.1.4 Detection Monitoring Program <br /> Field and laboratory results for the groundwater monitoring wells for the third quarter <br /> 2006 are summarized in Table 2-2 and Appendix D presents time-series charts of select <br /> DA2003 021�FomardAastla s®05.doc <br /> - - 5 Geologic Associates <br />