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with the same area. This is well located at the estimated center of the mined area. The total drawdown.(sraw) was <br />• calculated as the difference between the average floor elevation in the mined area and the estimated original <br />piezometric level in the Wadge Overburden of 6,900 feet. <br />Based upon the location of the mine well, an image well (l,) was located on the opposite side of the north boundary <br />of the Eckman Pazk Mine No. 1. When it is located west of the eastern boundary of the Eckman Park Mine No. 1, <br />it is a recharging well; when it is located west of this boundary, it is a discharging well. Based upon the location of <br />image well I,, a second image well (I=) was located on the opposite side of the eastern boundary of the Eckman Park <br />Mine No. 1. Image well IZ is always the opposite of image well l,. The distances from each image well (r, and rz) <br />to the mine well was then measured. <br />The drawdown was calculated using the following formula: <br />s = (114/6•Q/I')'W(u) <br />Where: <br />u = (0.00512*~'$)/(T't) <br />W(u) = the "well function for non-leaky artesian aquifers" (Wenzel, 1941) <br />s = drawdown, feet <br />Q = discharge, gpm <br />T = Transmissivity, gpd/ft <br />r = distance from pumping well to image wells Land Iz (r, and rz), or radius of pumping wells radius (r,,,;,K), feet <br />• S - storativity <br />time since pumping began, years <br />The total drawdown at the mine (slow) was calculated to be: <br />(slaw) _ (sue) f si t s2 <br />Where: <br />sm;M = calculated drawdown from the mine well (VV) alone, feet <br />s~ = calculated drawdown from W from image well I, where the sign is positive if it is a <br />rechazge well and negative if it is a discharge well, feet <br />sz =calculated drawdown at W from image well 12 where the sign is positive if it is a recharge well <br />and negative if it is a discharge well, feet <br />The above equation was solved for discharge (Q) yielding: <br />Q = (sTadFT)/[114.6'{W(u~rc) t W(u~) t W(uz)}] <br />The sign of the Well Function is positive if it is a recharge well and negative if it is a discharge well. <br />The discharge for a given mine area was calculated using a Microsoft Excel for Windows® spreadsheet on an IBM <br />compatible PC. Each longwall panel was assumed to be fully contributing to the flow when the gateroads around <br />the panel were completed (time t). Using this method, the transmissivity and storativity were adjusted until the <br />calculated discharges provided a reasonable match to the measured discharges. The measured discharges were <br />. taken from data in the 1993 through 1996 Annual Hydrology Reports for the Foidel Creek Mine. There is not a <br />good match in 1993 because I-South (the room and pillar area), which had been previously seated and flooded, was <br />p~Ph~©F~~fi1 JUN 2 8 2000 <br />PR 99-OS 2.05-171.11 8/27/99 <br />