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i Getty Task 2 Page 18 March 1, 1983 <br />r <br /> <br /> <br />5.0 RESULTS AND ANALYSES <br />After the model ras calibrated, simulation runs were performed to <br />r estimate the amount of inflow that the mine would receive as a function of <br />time. The time increment selected for the simulation runs was 360 days. <br />Based oa the mine plea prepared by Nor West, a total of 37 iterations was <br />`, required to simulate the entire mining period. As described earlier, the <br />model calculates both lateral inflow and vertical inflow through the overlying <br />marine shale from the Tweatymile sandstone. Plots of lateral inflow, vertical <br />inflow from the roof, and total inflow as functions of time are presented on <br />Figare S. As would be expected, the vertical inflow through the roof is a <br />function of only the emonat of active mine area daring the time increment. <br />` Lateral iaflors, oa the other hand, are effected by the drawdowa in the <br />aquifer due to previous removal of water by mining operations as well as the <br />~ amount of active mine area. Daring the first five years of mining, the <br />maximum amount of lateral inflow is 121 gpm chile the maximum vertical inflow <br />~ is 74 gpm for a total estimated inflow of 195 gpm. For the entire life of the <br />mine, the masimnm estimated iaf low is 877 gpm and occurs in the 10th year of <br />mining. <br />• The mean lateral inflow to the mine, calculated from the data presented <br />' on Figure 5, is 333 gpm. The total estimated volume of water removed from the <br />overburden aquifer is, therefore, 19,600 acre-feet. In a similar manner, the <br />~ mesa vertical inflow to the mine is 117 gpm and the total volume of water <br />! removed from the Tweatymile aquifer during the life of the mine is <br />~, approximately 6900 core-feet. The model also provides the drawdowa for each <br />grid as of the cad of the time step. Using these data, plots of predicted <br />drawdowa st times of 5, 10, and 37 years were prepared. These ds awdown maps <br />aze presented on Figures 6, 7, sad 8. <br />i, <br />S.1 Analyses of Results <br />~ As rith eny modeling procedure, sp pr oxima bons required to perform the <br />modeling can have as effect on the results obtained. With two dimensional <br />finite difference modeling, it is necessary to assume that the advance of the <br />mine causes an instantaneous drawdowa to the elevation of the bottom of the <br />coal. In reality, an advancing mine causes the drawdowa to occur only is the <br />• coal itself and the portion of the equifer overlying the coal is drained into <br />