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_ i=e <br /> 3-7 <br /> Site Hydrogevlogy <br /> The data collected from observation well W-2 was analyzed using the Generalized Straight- <br /> Line Method of Cooper and Jacob (1946)1. The method was used to determine the <br /> transmissivity(T)and hydraulic conductivity(K)of the material in the saturated zone around the <br /> well. Figure 3-5 is a plot of the drawdown (s) over discharge (Q) versus log 10 of equivalent <br /> time. Equivalent time is the time at which the observed drawdown would have occurred if the <br /> pumping had been done at a constant discharge rate equal to the actual discharge rate at a given <br /> time. <br /> -- T = 35.28 <br /> change in S/Q per log cycle (Figure 3-5) <br /> K = T/b <br /> - where, <br /> s = drawdown in ft <br /> - Q = discharge in gpm <br /> b = 20 ft thickness of the tested zone <br /> Using these formulas, the following calculations were made: <br /> - T =270 ft2/day <br /> K= 13.5 ft/day <br /> The hydraulic conductivity thus determined is in the range of values for fine sand(Driscoll, <br /> 1987, p. 75), which is consistent with the site geology. <br /> The data collected from E-I during the step-drawdown test is shown plotted on Figure 3-6. <br /> } The curve shows the response of the pumping well during and after pumping (recovery). <br /> As can be seen from Figure 3-6, the drawdown from the first step of I gpm stabilized <br /> during the 60-minute pumping period. The second step of 2.31 gpm exceeded the capacity of <br /> the well to provide water. The optimum pumping rate is therefore somewhere between 1 and 2.3 <br /> gpm. The recovery Jam indicates that the well fully recovered within approximately 40 minutes. <br /> I <br /> 1Cooper, H.H., and C.E. Jacob, 1946. A Generalized Gra hical Method for Evaluatin <br /> Formation Constants and Summarizin>;Well Field History. American Geophysical Union Trans., <br /> ! Volume 27: 526-534. <br /> F .. <br />