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regional aquifer. <br />The Twentymile Sandstone maybe slightly impacted by the mining operation. The <br />Bond Creek and Cow Camp Creek drainages intersect the dipping sandstone outcrop <br />adjacent to the southeastern portion of the permit area. The alluviaUcolluvial <br />material within each drainage will transmit water discharged from spoils aquifers <br />upgradient in each drainage. This water, which is high in TDS, may recharge the <br />Twentymile Sandstone at the point where the alluvial/colluvial material bisects the <br />outcrop. The potential for water quality degradation due to potential rechazge by the <br />poor quality alluviallcolluvial water, is the only identified potential impact to this <br />regionally significant aquifer. <br />The Wolf Creek Coal stratigraphicallyrhe lowest seam to be mined, along with its <br />associated overburden, is capable of storing and transmitting small amounts of <br />water, and in the permit azea, may not meet the defmition of an aquifer. Reported <br />yields from wells completed in the Wolf Creek Coal aze generally less than one <br />gallon per minute (GPM). Furthermore, high pre-mining concentrations of iron, <br />manganese and sulfate generally preclude use of tnis water for domestic or livestock <br />use. <br />The Seneca II Mine operation is removing the Wolf Creek Coal and overburden in <br />the north central portion of the active mine area, located within the regional Sand <br />Wash Basin. One consequence of mining will be the physical removal of this unit, <br />thus interrupting rechazge to the coal and overburden aquifer. <br />As the Wolf Creek mining azea is reclaimed, the backfilled mining pits will <br />gradually resaturate. Spoil aquifers will develop and dischazge to the surface <br />system. A small portion of the spoil aquifer water will recharge-the Wotf Creek <br />Coal and overburden with water which is higher in TDS than the water which <br />existed within the units prior to mining. <br />The Wadge Coal and overburden units aze aquifers which have potential for local <br />use. Well yields for the Wadge Coal and overburden have been reported at between <br />2 and 5 gpm. In the vicinity of the Seneca II Mine site, both units have been used for <br />domestic and livestock purposes. <br />The Wadge Coal has been mined in the northern portion of the permit azea <br />(Sand Wash Ground Water Basin) in the past. During previous permit terms, the <br />Wadge Coal was extracted from the southeastern portion of the permit area within <br />the Twentymile Park Basin. <br />The portion of Twentymile Pazk in which the Seneca II Mine is located has been <br />identified as a rechazge area. As such, the potential impacts of mining will be <br />threefold: <br />27 <br />