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Dewatering and potentiometric drawdown in bedrock units <br />Dewatering will occur in the Trout Creek Sandstone, Wadge Overburden, and Twentymile <br />Sandstone. Monitoring data have verified both that this dewatering has occurred and the <br />existence of a depression of the potentiometric surfaces of these hydrostratigraphic units in <br />the vicinity of the mine. <br />Diminution of bedrock discharge to alluvium and surface streams <br />Gradient reversal due to mining could cause a decrease in natural discharge to alluvium and <br />streams. This would persist for approximately 360 years until potentiometric levels recover <br />to pre -mining conditions. Discharge of mine water discharge to the streams will more than <br />offset this loss, which is estimated at approximately .02 cfs in Fish Creek. <br />Degradation of Wadge overburden water <br />Only the Wadge overburden aquifer is predicted to be degraded with regard to water quality. <br />Estimates indicate that degraded water will persist for 23,000 years. Conductivity of <br />degraded water is estimated at 4000-7000 umhos/cm. Areas immediately down gradient will <br />be affected to a greater degree due to the close proximity to the source (mine workings). <br />Due to dilution and dispersion, water quality will generally improve as the distance from the <br />mine workings increases. Wadge overburden water is not presently used on the Twentymile <br />Park basin. <br />Degradation of alluvial water quality in Fish Creek <br />Water will move down gradient to the natural discharge points along Fish Creek. Alluvial <br />aquifers are recharged mainly by stream flows during high flow conditions and to a lesser <br />degree, bedrock discharge. Given the small amount of estimated discharge, this degraded <br />water will easily be diluted by upstream flows. <br />Degradation of alluvial water quality in Foidel Creek <br />Only the area near the confluence of Foidel and Middle Creeks contain adequate saturation <br />to be measured. As with Fish Creek, the water near the confluence of Foidel and Middle <br />Creeks will move down gradient to the natural discharge points along Middle Creek. <br />Alluvial aquifers are recharged mainly by stream flows during high flow conditions and to a <br />lesser degree, bedrock discharge. Given the small amount of estimated discharge, any <br />degraded water will easily be diluted by upstream flows. <br />Subsidence impacts to bedrock aquifer water quantity <br />Although the applicant presents no site specific information, the predicted consequences of <br />subsidence and effects to ground water quantity can be summarized as follows: <br />Foidel Creek Mine 19 August 10, 2018 <br />