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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 /> a) Longwall operation induced subsidence creates a zone of increased permeability <br /> above the mined-out area and within a 15 to 25 degree angle of draw. <br /> b) Cracking and opening of fissures at the ground surface can occur within the zone of <br /> tensile strain. However, the depth of such subsidence fractures is limited. <br /> c) The zone of increased permeability above the longwall operation is typically 30 to <br /> 50 times the thickness of the removed strata. <br /> d) The thickness of the zone of increased permeability is dependent on the thickness of <br /> the removed strata; speed of mining; and geologic character of the overburden. <br /> After completion of mining, the permeability of the disturbed strata is predicted to <br /> return to close to pre-mining conditions. <br /> Subsidence impacts to alluvial water quantity <br /> Alluvial waters should not be impacted due to mining and subsidence, due to the presence of <br /> a 500-600 foot thick marine shale above the mined Wadge seam which acts as an aquiclude <br /> and minimizes the disruption in the near surface. Previous subsidence along Fish Creek in <br /> the Western Mining District recorded only minimal changes in the water levels in the <br /> alluvial aquifer in Fish Creek. <br /> Subsidence impacts to ground water quality <br /> The mine predicts that subsidence fracturing could cause a new hydrologic communication <br /> between bedrock units with different quality. However, the applicant states that monitoring <br /> does not indicate any substantial intercommunication of bedrock or alluvial aquifers. <br /> Compliance with Basic Standards for Ground Water(Regulation 41 of the Colorado Water <br /> Quality Control Commission) <br /> Section 4.05.13(1) of the Regulations requires the establishment of one or more ground <br /> water points of compliance (well)for an operation which has the potential to negatively <br /> Foidel Creek Mine 18 August 4,2023 <br />