Laserfiche WebLink
erection 780.21 (c) Continued. <br />as to include the entire Eckman Park and Energy Mine No. 1 mined <br />area, because the confining layers will be removed and replaced <br />with unconsolidated backfill. Another factor to consider, while <br />difficult to quantify, is that the permeability of the backfill <br />will exceed that of the undisturbed aquifer. Both of these factors <br />balance against the expected decrease in infiltration rates in <br />estimating the postmining ground water recharge capacity of the <br />overburden aquifer. Since the proposed areas of disturbance at <br />mines No. 1 and Eckman Park amount to about 4,000 acres, and <br />assuming an annual precipitation rate of 16 inches per year and <br />that 25 percent of this precipitation will infiltrate into the <br />substrate, the postmining recharge rate should be 1,330 acre-feet <br />per year, or 190,000 gpd/square mile. This increased rate of <br />recharge will enable rapid recovery of the original storage volume <br />of the undisturbed overburden aquifer from the temporary dewatering <br />due to mining. Thus, the hydrologic balance of ground water systems <br />• will be restored after mining and reclamation is completed. <br />Solute Leaching. A potential impact of mining on ground water <br />quality is the increased dissolution of solids from physical modi- <br />fication of overburden into water which has saturated spoil ma- <br />terial. The reasons for increased leaching are: 1) greater quan- <br />tities of water are able to move through spoil; and 2) a greater <br />amount of surface area of spoil fragments and particles is exposed <br />to water. <br />In an attempt to quantify the amount of solute leaching which will <br />take place as a result of proposed mining operations, and in order <br />to adequately address 30 CFR 780.21 (c), Energy Fuels cooperated <br />with Dr. Herbert Gardner in his work on a leaching study on over- <br />burden material collected from the mine plan area. Dr. Gardner is <br />with the Science and Education Administration of the U. S. Depart- <br />. ment of Agriculture at the Colorado State University campus in Ft. <br />Collins, Colorado, and is recognized as an expert in the field of <br />spoil leaching. <br />780-182 <br />