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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 />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) Increased permeability above mined area, especially within 300 feet of the mine <br />roof. <br />b) Cracking, of limited depth, of the ground surface above the mined area. <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 />data recorded does not indicate any substantial intercommunication of bedrock or alluvial <br />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 require the establishment of one or more ground water <br />points of compliance (well) for an operation which has the potential to negatively impact the <br />quality of groundwater. The Wadge overburden and the Twentymile Sandstone are the two <br />major aquifers most likely to be affected by the Foidel Creek Mine. The following wells <br />serve as the Foidel Creek Mine's groundwater points of compliance: 97013TM (Twentymile <br />sandstone), 008-77-58 (Wadge overburden), 008-AU3 (Fish Creek alluvium), and 008-AT-1 <br />(Trout Creek alluvium). The mine's annual hydrology reports contain long-term data from <br />these wells. These data show Foidel Creek Mine is in compliance with the Basic Standards <br />for Ground Water at the groundwater points of compliance. <br />Surface water <br />Several possible effects on the surface water system have been identified: <br />Foidel Creek Mine 20 June 4, 2010