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7.2 Pumping Well EW-513 GeoHydrologlc Consultants, Inc Monitoring well EW-5D is a 4-inch diameter well that is installed to a depth of 85 feet bgs, with 0 010-inch slotted well screen from 65-85 feet bgs The sand pack extends ' approximately two feet above the top of screen Groundwater appears to be present under unconfined water-table conditions Static groundwater was measured prior to conducting the pumping test in EW-5D at a depth of 47 47 feet bgs, indicating an estimated aquifer thickness of approximately 40 feet The pumping test was started at 6 35 AM on March 31, 2005 and was maintained at a constant pumping rate of approximately 2 3 gallons per minute (gpm) for 745 minutes, terminating at 7 00 PM that evening A total of approximately 1,400 gallons of water was removed during the pumping test and stored onsite in a 4,000-gallon polyethylene Baker ' Tank All water generated during the test was vacuum trucked from the tank and properly recycled/disposed Drawdown was measured and recorded at regular intervals throughout the test from the pumping well EW-513 and observation wells EW-5S, MW-4, TB-10, and TB-7 The maximum observed drawdown in the extraction well EW-5D was 5 40 feet at the end of the test, while the maximum drawdown measured in observation well EW-5S was 0 05 feet at 385 minutes, the maximum drawdown measured in observation ' well MW-4 was 0 05 feet at 325 minutes, the maximum drawdown measured in observation well TB-7 was 0 10 feet at 235 minutes, and the maximum measured drawdown in observation well TB-10 was 0 08 feet at 265 minutes '.! Figure 6A illustrates the drawdown graph for the pumping well EW-5D and Figures 613 and 6C illustrates the drawdown graphs for observation wells TB-7 and TB-10 The drawdown and recovery data for this well is summarized in Table l0A and copies of field data are included in Appendix D ' Analysis of drawdown data for EW-5D is presented in Table 7 2-1, TB-7 is presented in Table 7 2-2, and TB-10 is presented in Table 7 2-3 An estimated saturated thickness of 40 feet was assumed from the well depth, static groundwater level the day of the pumping ' test, and the lithologic logs for the Site According to Todd (1980), hydraulic conductivities in this range are representative of soils consisting of silt to medium sand, which is representative of the sediment described in the boring log for EW-5D at the depths of this well It should be noted that if vertically thinner saturated thicknesses were assumed, the calculated hydraulic conductivity would increase accordingly 1 TOC 171 Pilot Study Page 19