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S. Restoration of <br />ground water <br />recharge to <br />approximate pre- <br />mining rate <br />CDRMS <br />regulation <br />4.05.11(3) <br />yes <br />Each pit disrupts the potentiometric surface of confined <br />aquifers. After reclamation, monitoring data show full <br />recovery of the potentiometric surface outside of backfilled <br />pits and partial recovery of potentiometric surface inside <br />backfilled pits. Spoil springs may reduce groundwater <br />recharge by diverting groundwater flow to surface flow. <br />However, Trapper's expected total aggregate spoil spring <br />discharge of less than 1 cfs will be too small to reduce <br />recharge below the approximate pre- mining rate. <br />The Probable Hydrologic Consequences (PHC) section of <br />Trapper's mining and reclamation permit (Section 4.8.3) <br />discusses the possibility of a high -TDS plume of coal spoil <br />leachate forming in the Third White Sandstone downgradient <br />from the Trapper Mine in Section 29- T6N -90W. Such a <br />plume would not be expected to form until several years, <br />possibly decades, after the pit is reclaimed in the adjoining <br />Section 32. Compared to pre - mining ground water conditions, <br />such a plume would have elevated dissolved solids, which <br />T. Prevention of <br />could possibly impair the use of ground water in the Third <br />adverse impacts <br />CDRMS <br />White Sandstone. <br />to ground water <br />regulation <br />yes <br />Spoil leachate could also invade the alluvium in Flume Gulch <br />systems outside <br />4.05.11 <br />by seeping down into the subsurface from spoil springs <br />the permit area <br />flowing on the land surface in the gulch. <br />The Third White Sandstone is monitored in the area of the <br />possible plume in well GP -9, and the alluviums is monitored <br />with the Coy well. Monitoring data from both wells indicate <br />that a plume has not formed. For the Third White Sandstone, <br />this could be the consequence of artesian conditions that are <br />preventing invasion in the subsurface by spoil leachate. <br />Page 5 <br />