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Since the coal in the No. 6 mine is very similar to the No. 5 Mine coal, the same aquifer properties are assumed to <br />apply. The McWhorter method has been used to estimate drawdown in the coal seam, but not mine inflows. The <br />method, as described in the subsection titled "Impacts on Aquifers ", was developed to estimate drawdown associated <br />with an open coal face and may have limited applicability to longwall mining. <br />Inflow to the No. 6 Mine was estimated using the Jacob - Lohman constant drawdown equation and the Theim steady <br />state equation. During the first five years of mining, almost all the No. 6 Mine will be directly under old workings of <br />the No. 5 Mine (refer to the No. 5 Mine Plan Map, Map 23). It is anticipated that the No. 5 Mine will be continued to <br />be dewatered during the mining of the No. 6 Mine. Due to these conditions, it was therefore assumed, that almost all <br />inflow to the No. 6 Mine through year 5 will come from dewatering the rock between the No. 6 and No. 5 Mines - an <br />initial static head of approximately 100 feet. <br />Beginning in year six, the No. 6 mine will extend beyond the No. 5 Mine. The initial static head is assumed tc <br />average 700 to 800 feet. This is a very conservative assumption because the previous dewatering of the No. 5 and No. <br />6 Mines will have reduced this head. <br />Jacob - Lohman Method. This method assumes that the mine is a large well with constant drawdown and an inflow <br />varying with time. The radius of the "well" was estimated by calculating the radius of the circle with an area equal to <br />the area mined. This equation assumes artesian conditions; however, it has been found to provide a reasonable <br />approximation of mine dewatering inflows where the initial artesian head is large and the radius of the assumed well is <br />large. The equation used is as follows: <br />Q= 2Ts,G(a) <br />a = Tt/S r,,,2 <br />Q = flow rate <br />T = transmissivity <br />s' = drawdown at well <br />S = storativity <br />r,,, = well radius <br />G(a) = constant drawdown equation <br />The calculated inflows for the No. 5 and No. 6 Mines are presented n Table 75, Estimated Mine Inflows. The input <br />data for the No. 6 Mine is presented in Table 76, Summary of Mine Inflow Input Data - No. 6 Mine. This method is <br />most applicable to the No. 6 Mine inflows after the start of extensive paneling (the time the mine most closely <br />approximates a large diameter well). The input data for the No. 5 Mine has been taken from the original RAG Empire <br />Permit (1983), and is presented in Exhibit 31, Mine Inflows - No. 5 Mine. <br />Theim Method. The Theim equation is a steady -state formula in which the inflow to the mine is a function of the <br />radius of the cone of influence. For artesian conditions, the cone of influence is generally assumed to be 10,000 feet <br />for the purposes of this equation. The radius of the well is calculated in the same manner as for the Jacob - Lohman <br />method. The Theim equation is as follows: <br />Q = T H-h <br />528 logio (R/r) <br />Q = flow rate, gpm <br />T = transmissivity, gpd/ft <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 />TR14 -36 2.05 -38 Revised 06/23/14 <br />