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• Theis equation: <br />well function variable <br />1.87r2 S 1.87(100012 (0.01) <br />U= Tt 250(365) = 0.20 <br />well function W(u) = 122 <br />drawdown s =114.6 TW(u) = 114.6(701 50 2) = 39 ft. <br />Therefore, only a few tens of feet are expected at 1,000 feet from the pit after a year. <br />For: Drawdown estimate at four years and one mile. <br />Q r = 5280 ft and t = 4 yrs (1460 days) <br />1.87(5280)2 (0,01 <br />u = 250(1460) = 1.43 <br />W(u) = 0.11 <br />• 114.6(70)(0.11) <br />s = 250 .5 ft. <br />Therefore, after four years, drawdowns of only a few feet would be expected at one mile from the pit. <br />However, the rate the pits move will prevent wells in one area from feeling the impacts of numerous years <br />of mining. Only wells adjacent to the mine pits and completed in the coal aquifers which are being mined <br />are likely to observe any drawdown. <br />4-226 <br />Revision: -.LL- s <br />