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Page 6 <br />The post - mining uses of ground water in the pen area will <br />be irrigation and livestock uses. Only the three large sandstone <br />aquifers within the upper Williams Fork Formation at Trapper <br />(Twenty Mile Sandstone, Second White Sandstone, and Third <br />White Sandstone) could reasonably be expected to yield <br />enough high quality water to serve as a local supply source. <br />Coal aquifers in the area possess neither the deliverability nor <br />water quality to be considered for reliable water supplies. <br />The Twenty Mile Sandstone is the only regionally extensive <br />aquifer in the vicinity of the Trapper Mine. It is several <br />hundred feet deeper than the deepest mining at Trapper and <br />has shown no effect from Trapper's mining based on <br />monitoring data from well GF -1 and previously from well GD- <br />1(2). <br />The Second and Third White Sandstone aquifers overlie the <br />stratigraphic sequence being mined at Trapper. TDS <br />concentrations in both of these aquifers have increased over <br />U. Prevention of <br />the past several years based on monitoring of wells P -5 and P- <br />impacts to ground <br />CDRMS <br />8, which are in the East Pyeatt Gulch basin. <br />water that <br />regulations <br />adversely impact <br />4.05.1(2) and <br />yes <br />In 2011, elevated levels of TDS were detected in wells GD -2 <br />the postmining <br />40511 <br />and GD -3 (spoil backfill). GD -2 is down- gradient of GD -3 <br />land use within <br />.. <br />which has increased in TDS in 2008 to 2011 which could be <br />the permit area <br />the movement of higher concentrations from GD -3 area to <br />well GD -2. The TDS levels in the backfill aquifer may be <br />due to leaching from backfill material, but these levels were <br />reported to be well within their natural limits. <br />In 2011, GMP -1 well indicated higher levels of TDS. This <br />well is down gradient from the reclaimed A -pit and is likely <br />showing fluctuations from the backfilled aquifer. According <br />to the report, other wells monitored in this specific area and <br />aquifer have TDS levels that naturally vary significantly over <br />the area. <br />Trapper believes the TDS and conductivity concentrations will <br />eventually subside, possibly hundreds of years after mining <br />and reclamation, as discussed in Section 4.8.3 of the permit. <br />The suitability of Trapper's ground water for livestock and <br />wildlife is expected to continue into the future based on long- <br />term trends in Trapper's water quality data. <br />V. Minimization of <br />disturbance to the <br />CDRMS <br />hydrologic <br />regulation <br />yes <br />balance within <br />4.05.1(1) <br />and adjacent to <br />the permit area <br />Page 6 <br />