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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 streams. <br />This would persist for approximately 360 years until potentiometric levels recover to pre-mining <br />conditions. Discharge of mine water discharge to the streams will more than offset this loss, which is <br />estimated at approximately 0.02 cfs in Fish Creek. <br />Deeradation of Wadee overburden water <br />Only the Wedge 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 degraded water is <br />estimated at 4000-7000 umhos/cm. Areas immediately downgradient will be affected to a greater <br />degree due to the close proximity to the source (mine workings). Due to dilution and dispersion, water <br />quality will generally improve as the distance from the mine workings increases. Wedge overburden <br />water is not presently used in the Twentymile Park basin. <br />Deeradation of alluvial water qualiri in Fish Creek <br />This water will move downgradient to the natural discharge points along Fish Creek. Alluvial aquifers <br />are recharged mainly by stream flows during high flow conditions and to a lesser degree, bedrock <br />discharge. Given the small amount of estimated discharge, this degraded water will easily be diluted <br />by upstream flows. <br />Subsidence impacts to bedrock aquifer water quantity <br />Although the applicant presents no site specific information, the predicted consequences of subsidence <br />and effects to ground water quantity can be summarized as follows: <br />a) Increased permeability above mined area, especially within 300 feet of the mine roof. <br />b) Cracking, of limited depth, of the ground surface above the mined area. <br />Subsidence impacts to alluvial water guantiri <br />Alluvial waters should not be impacted due to mining and subsidence, due to the presence of a 500- <br />600 foot thick marine shale above the mined Wedge seam which acts as an aquiclude and minimizes <br />the disruption in the near surface. Previous subsidence along Fish Creek in the Western Mining <br />District recorded only minimal changes in the water levels in the alluvial aquifer of Fish Creek. <br />Subsidence impacts to around water aualiri <br />The mine predicts that subsidence fracturing could cause a new hydraulic connection between bedrock <br />units with different quality. However, the applicant states that monitoring data recorded does not <br />indicate any substantial intercommunication of bedrock or alluvial aquifers. <br />Compliance with Basic Standards for Ground Water <br />SRegulation 41 of the Colorado Water Quality Control Commission) <br />Section 4.05.13(1) of the Regulations require the establishment of one or more ground water points of <br />compliance (wells) for an operation which has the potential to negatively impact the quality of ground <br />11 <br />