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varied until a reasonable match to observe flows was obtained. The values of (T) and (S) that produced the best were <br />30 ft/day (225 gpd/ft.) and 0.002 respectively. It was found that the values for transmissivity and storativity used for <br />the No. 9 mine produced a reasonable fit to observed flows in the No. 5 mine as well. <br />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 described in the subsection titled "Impacts on <br />Aquifers" was developed to estimate drawdown associated with an open coal face and is not as applicable to longwall <br />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 (5) years of mining, almost all the No. 6 Mine will be directly under old workings <br />of 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 <br />to be dewatered during the mining of the No. 6 Mine. Due to these conditions, it was therefore, assumed that almost <br />all inflow to the No. 6 Mine through year 5 will come from dewatering the rock between [he No. 6 and No. 5 Mines - <br />an 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 to <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 lazge and the radius of the assumed well is <br />large. The equation used is as follows: <br />Q = 2 T sw G(a) <br />a = Tt/S rwZ <br />Q =flow rate <br />T =transmissivity <br />s"' =drawdown at well <br />S =storativity <br />rw =well radius <br />G(a) =constant drawdown equation <br />The calculated inflows for the No. 5 and No. 6 Mines is 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 EC Permit <br />(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 = ~-~ <br />528 logo (R/r) <br />Q =flow rate, gpm <br />T =transmissivity, gpd/ft <br />Permit Revision 04-34 2.05-38 Revised 7/2/0 <br />