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• Longwall mining is proposed for portions of the Empire Tract (including <br />most of the Utah Tract). It is not anticipated that longwall mining <br />will produce any more flow per unit area mined than conventional mining <br />methods. In those areas of the No. 5 Mine where complete extraction has <br />been carried out in the past, the inflows are not detestably higher than <br />those adjacent areas that have only been roomed. <br />McWhorter Method. This method assumes that the flow into the mines is a <br />function of the time since mining of each main began (t), the rate of <br />advancement of each main (R), and the length of each main (L). It does <br />not take into account the total area mined. The formula is as follows: <br />0.5 0.5 <br />Q = 4R (S Tbz/12) + (STHoz/4) * t <br />Q <br />R <br />• Sy <br />S <br />T <br />b <br />Ho <br />t <br />L <br />discharge to the mains <br />rate of advancement of the mains <br />apparent specific yield <br />storativity <br />transmissivity <br />thickness of the coal <br />initial piezometric height above the top of the coal seam <br />time since the initiation of the main <br />maximum length of the main <br />Once the mine reaches maximum length, the mine inflow is calculated by <br />the following equation: <br />Q =(4R (Sy Tbz + ST Hoz)0.5 *(t0.5 _/t - L/R)~'% t ~L/R <br />`` 12 4 l <br /> <br />-5- <br />