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Theis equation: <br />well function variable <br />2 2 <br />1.87r 5 1.87(1000) (0.01) <br />u = Tt 250(365) = 0.20 <br />well function W(u) = 122 <br />114.60 114.6(70) <br />drawdown s = W(u) _ (1.22) = 39 ft. <br />T 250 <br />Therefore, only a few tens of feet are expected at 1,000 feet from the pit after <br />a year. <br />For: Drawdown estimate at four years and one mile. <br />• @ r = 5280 ft and t = 4 yrs (1460 days) <br />2 <br />1.87(5280) (0.01) <br />u = 250(1460) = 1.43 <br />W(u) = 0.11 <br />114.6(70) (0.11) <br />= 3.5 ft. <br />s = 250 <br />Therefore, by 1985, drawduwns of only a few feet are expected at one mile from <br />the pit. The rate the pits move wiil prevent we1Ls in one area from feeling the <br />impacts of numerous years uE mining. Only wells adjacent to the mine pits and <br />completed in the coal aquifers which are being mined are likely to observe any <br />drawduwn. <br />i 4-226 <br />REVISES FEB 13'07 <br />