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8. Pre-law leachate vs. post-law leachate - Spoil springs that pre-date <br />SMCRA will hinder recognition of the hydrologic impacts resulting <br />from mining completed since the enactment of SMCRA (page 2.5- <br />104). <br />9. Duration of elevated dissolved solids in leachate -The elevated <br />dissolved solids will persist for a few hundred years (page 2.5-105). <br />Observed Impacts <br />Post-mining infiltration rate of meteoric water -Continuous spoil <br />spring flows totaling more several hundred gpm indicate that at least <br />1.95 inches of meteroic water is annually infiltrating into the <br />approximately 3,000 acres of disturbed ground surface (annual <br />hydrology reports). <br />2. Spoil saturation -The formation of spoil springs indicates the <br />infiltrating meteoric water has saturated spoil in the toe (northwestern, <br />down-dip end) of each backfilled pit (annual hydrology reports). <br />Spoil leachate quality -TDS has fluctuated azound 3500 mg/1 in [he <br />only spoil well, WR-1 (annual hydrology reports). <br />4. Discharge of leachate from pit -TDS loading of Trout Creek <br />immediately downstream from the Edna Mine and the formation of <br />spoil springs indicate leachate is dischazging from pits at the mine <br />(page 2.SB-L of Appendix 2.SB). <br />5. Leachate impacts on bedrock ground water -Mining operations left a <br />wedge of unmined bedrock less than 1,000 feet wide at the toe of the <br />pits that lies between the toe of the pits and Trout Creek. This unmined <br />rock is believed to transmit leachate from the backfilled pits to the <br />rock's outcrop next to Trout Creek and to its subcrop beneath Trout <br />Creek, resulting in [he leachate flowing into the creek's surface water <br />and alluvium, rather than to bedrock downdip from the creek. <br />Consequently, no impacts to bedrock ground water aze suspected. <br />Substantial leachate dischazge to bedrock in the bottom of Edna's pits <br />would not be possible due to the impermeable shale and siltstone that <br />underlies the Wadge seam as shown on lithologic and geophysical logs <br />in Section 2.2.4.1 of the permit application. The mining operation can <br />be expected to be in compliance with the basic standards for ground <br />water for a compliance point in any stratigraphic unit at the permit <br />boundary. Monitoring data from well TCS, immediately downdip <br />from the permit boundary, indicates the Trout Creek Sandstone has not <br />Edna Mine 22 Permit Renewal No. 4 <br />