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Recharge Capacity <br />Surface mining at Energy Mine No. 3 has resulted in greater <br />permeability and recharge capacity of the Wadge Overburden <br />Aquifer than in the pre-mining condition. The pre-mining <br />recharge area for the Wadge Overburden Aquifer was a narrow <br />strikeline covering about 33.5 acres where the aquifer <br />outcropped at the surface (see Map 4a, Mine No. 3 Hydrology). <br />Surface mining has resulted and will result in an expansion of <br />the post-mining recharge area to include the entire mined area, <br />which will amount to approximately 525 acres. <br />The applicant has estimated that the Dost-mining recharge rate <br />should be about 140 acre-feet per year (page 2.05-167a1. This <br />is compared to an estimated pre-mining recharge rate of <br />9 acre-feet per year (page 2.04-411. This increase in <br />post-mining recharge capacity will provide an additional <br />131 acre-feet per year to the undisturbed Wadge Overburden <br />Aquifer. <br />An analysis was performed by the applicant to evaluate the <br />capability of the undisturbed Wadge Overburden Aquifer to <br />transmit this increased volume of water. Using an average <br />permeability for the Wadge Overburden Aquifer of 3.4 gallons <br />per day Der foot squared (gpd/ft21 (page 2.04-401, average <br />highwall height of 60 feet, and highwall length of 15,000 feet, <br />it was calculated that the Wadge Overburden Aquifer is capable <br />of transmitting about 3,400 acre-feet per year <br />(page 2.05-168a1, Based on this analysis, it is expected that <br />recharge to the backfilled spoils (140 acre-feet per year) <br />would be absorbed by the undisturbed Wadge Overburden Aquifer. <br />Solute Leaching <br />Solute leaching as water percolates through the backfilled <br />spoils at Energy Mine No. 3 has been predicted to increase the <br />TDS concentration in the Wadge Overburden Aquifer as a result <br />of mining operations. In an attempt to quantify the amount of <br />solute leaching which will take D1 ace as a result of mining <br />operations, a column leaching study was performed on overburden <br />collected from CYCC's Eckman Park Mine, located approximately <br />seven miles southwest of Energy Mine No. 3. <br />One of the results of this study was a determination of the <br />amount of time necessary to leach the spoil until the solute <br />concentration returned to baseline ground water levels. This <br />value was calculated by the applicant to be 64.2 years <br />(page 2.05-171 a). <br />-26- <br />