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The intervening strata between the Wolf Creek Coal and the Trout Creek Sandstone, <br />which consists of lenticular sandstone lenses, shale and siltstone, has been identified as <br />a confining layer in this area. This confining layer, which will not be actively disturbed <br />by mining, will mitigate mining related impacts to the Trout Creek Sandstone. There <br />will be no depletion or degradation of the water in this regional aquifer. <br />The Twentymile Sandstone may be 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 alluvial/colluvial material <br />within each drainage will transmit water discharged from spoils aquifers upgradient in <br />each drainage. This water, which is high in TDS, may rechazge the Twentymile <br />Sandstone at the point where the alluvial/colluvial material bisects the outcrop. The <br />potential for water quality degradation due to potential recharge by the poor quality <br />alluvial/colluvial water, is the only identified potential impact to this regionally <br />significant aquifer. <br />The Wolf Creek Coal stratigraphically the lowest seam to be mined, along with its <br />associated overburden, is capable of storing and transmitting small amounts of water, <br />and in the permit azea, may not meet the definition of an aquifer. Reported yields from <br />wells completed in the Wolf Creek Coal are generally less than one gallon per minute <br />(GPM). Furthermore, high pre-mining concentrations of iron, manganese and sulfate <br />generally preclude use of this water for domestic or livestock use. <br />The Seneca II Mine operation is removing the Wolf Creek Coal and overburden in the <br />north central portion of the active mine area, located within the regional Sand Wash <br />Basin. One consequence of mining will be the physical removal of this unit, thus <br />interrupting rechazge to the coal and overburden aquifer. <br />As the Wolf Creek mining azea is reclaimed, the backfilled mining pits will gradually <br />resaturate. Spoil aquifers will develop and discharge to the surface system. A small <br />portion of the spoil aquifer water will recharge the Wolf Creek Coal and overburden <br />with water which is higher in TDS than the water which existed within the units prior to <br />mining. <br />The Wadge Coal and overburden units are aquifers which have potential for local use. <br />Well yields for the Wadge Coal and overburden have been reported at between 2 and 5 <br />gpm. In the vicinity of the Seneca II Mine site, both units have been used for domestic <br />and livestock purposes. <br />The Wadge Coal has been mined in the northern portion of the permit area (Sand Wash <br />Ground Water Basin) in the past. During previous permit terms, the Wadge Coal was <br />extracted from the southeastern portion of the permit azea within the Twentymile Pazk <br />Basin. <br />The portion of Twentymile Pazk in which the Seneca II Mine is located has been <br />26 <br />