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been identified as a confining layer in this area. This confining layer, which will <br />not be actively disturbed by mining, will mitigate mining related impacts to the <br />Trout Creek Sandstone. There will be no depletion or degradation of the water in <br />this regional aquifer. <br />The Twentymile Sandstone may be slightly impacted by the mining operation. <br />The Bond Creek and Cow Camp Creek drainages intersect the dipping sandstone <br />outcrop adjacent to the southeastern portion of the permit area. The <br />alluvial/colluvial material within each drainage will transmit water discharged <br />from spoils aquifers upgradient in each drainage. This water, which is high in <br />TDS, may recharge the Twentymile Sandstone at the point where the <br />alluvial/colluvial material bisects the outcrop. The potential for water quality <br />degradation due to potential recharge by the poor quality alluvial/colluvial water is <br />the only identified potential impact to this regionally significant aquifer. <br />The Wadge Coal and overburden units are aquifers which have potential for local <br />use. Well yields for the Wadge Coal and overburden have been reported at <br />between 2 and 5 gpm. In the vicinity of the Seneca II Mine site, both units have <br />been used for domestic and livestock purposes. <br />The Wadge Coal has been mined in the northern portion of the permit area <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 Park in which the Seneca II Mine is located has been <br />identified as a recharge area. As such, the potential impacts of mining will be <br />threefold: <br />(1) Interruption of the aquifer by physically removing the coal and its <br />overburden. Mining of the coal will interrupt the aquifer function <br />upgradient of Twentymile Park. This will reduce the recharge potential to <br />the down-gradient aquifer for a short period of time. <br />(2) After discreet mining areas have been backfilled, the spoils will resaturate. <br />A portion of the spoil water will recharge the undisturbed Wadge Coal and <br />overburden immediately down-gradient. This recharge water will be high <br />in TDS and other constituents. The concentrations of these constituents <br />will be greater than that which existed in the Wadge Coal and overburden <br />aquifer prior to mining. <br />(3) It is thought that the Wadge overburden, through sub-crops and outcrops, <br />may recharge creeks within Twentymile Basin. This recharge may be <br />directly affected by the addition of the poor quality spoil discharge water <br />during base flow conditions, or indirectly by the addition of this water to <br />19