Laserfiche WebLink
<br /> <br />I <br />Section 780.21(c) Continued. <br />v 1.49 x 109 cubic feet <br />i 2.1I x 106 cubic feet/year, based on the assump- <br />tion that 20% of the assumed mean annual <br />precipitatlon of 11 inches infiltrates <br />into the spoil. This is discussed in more <br />detail in this Section under the heading, <br />Recharge Capacity. <br />Thus, it can be predicted Lhat within 829 years spoil leachate will <br />be within baseline concentrations. The analysis of leaching poten- <br />tial presented in this Section was performed by Kerr Coal personnel <br />on data supplied by Dr. Gardner and does not reflect any assump- <br />tions or conclusions made by Dr. Gardner or USDA-SEA. <br />I • <br />Solute Transport <br />Dissolved solids leached out of the overburden backfill will con- <br />tribute additional salt load to ground water in the adjacent area. <br />Since mining will be conducted in the coal aquifer recharge area, <br />solute contribution can be expected to spread into the undisturbed <br />portion of the coal aquifer down-gradient from the active mining <br />area. No site-specific data indicating solute contribution to the <br />undisturbed coal aquifer resulting from mining have been collected <br />to date. <br />Water which infiltrates into the backfilled mine pits will dlssolve <br />the soluble minerals in the spoils at an accelerated rate, due to <br />the increased surface area of the broken rock. Leachate water will <br />percolate downward through the backfill and flow down-gradient to <br />the backfilled mine floor. There it will pool up above the less <br />• <br />permeable undisturbed coal aquifer providing recharge water to the <br />aquifer. As the leachate water enters the aquifer, it will be <br />diluted by less saline natural ground water. A "plume" of rela- <br />tively saline water will emanate from the mine plan area through <br />780-120 <br />