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where: <br />Qi = Aquifer discharge at any time increment and the other • <br />variables are as defined above, only for time increment <br />i. <br />If the aquifer discharge truly does become zero at time to then <br />the drawdown at time = tI can be determined by: <br />o t <br />SI = o In 1 <br />4 atl tl-to <br />from which the transmissivity (T1) can be calculated using the <br />measured drawdown (Si) at time tl. Because the aquifer <br />discharge at tI is not zero and significant afterflow has been <br />neglected, the transmissivity at tl wilt be a poor <br />approximation to the actual transmissivity. <br />The effects of afterflow on the calculated transmissivity can • <br />be reduced by performing a series of successive approximations <br />on the transmissivity until the actual transmissivity is obtained. <br />The generalized form of this equation is: <br />i to n-1 to - tI-1 <br />Tn = a~ ( Qo I n ~--~- + a Q i I n t- t ) <br />n n a i=1 n i <br />where: <br />n =Number of approximations <br />Tn = Transmissivity at the nth approximation <br />to = Time at approximation n <br />Qo Discharge rate during pumping phase <br />Qi = Determined from Equation 3 <br />srt = Drawdown at time n <br />The results of the tests on monitor wells GW-N9, N13, and N15 <br />were plotted on semi-logarithmic graph paper (see Appendix F) , <br />and attempts were made to match the data curves to one of the <br />82 <br />