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• Thiem Method. The Thiem equation is a steady state formula in which the <br />inflow to the mine is a function of the radius of the cone of influence. <br />For artesian conditions, the cone of influence is generally assumed to <br />be 10,000 feet for the purposes of this equation. The radius of the <br />well is calculated in the same manner as for the Jacob-Lohman method. <br />The Thiem equation is as follows: <br />Q _ T H-h) <br />528 1a910 (R/r) <br />Q = flow rate, gpm <br />T = transmissivity <br />H = static head from bottom of aquifer, ft. <br />h = height of water above bottom of aquifer at distant, ft. <br />R = radius of cone of depression, ft. <br />r = radius of a point on cone of depression, ft: <br />The calculated inflows are presented on Table 2, Estimated Mine Inflows <br />• - No. 5 Mine. The input data is presented on Table 3, Summary of Mine <br />Inflow Input Data - No. 5 Mine. Since this is a steady-state equation, <br />it is most applicable to situations where the size of the mine has not <br />changed for a long period. The conditions in the last stages of mining <br />would most closely fit the steady-state conditions. <br />2 West Mains Inflow <br />A major fault zone was encountered in the 2 West Mains of the No. 5 Mine <br />in June, 1981. However, the fault zone was not crossed until January, <br />1982, at which time additional inflow was encountered. Initial inflows <br />were of the order of 600+ gpm and as of May, 1983, were 363 gpm. Based <br />upon more recent data, the estimations of the fault zone and effects on <br />the adjacent aquifers have been revised. <br />Since such a relatively large quantity of water is issuing from a small <br />area of the mine, it is assumed that a large part of the flow may be <br />• <br />-10- <br />