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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 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 the <br />Western Mining District recorded only minimal changes in the water levels in the alluvial <br />aquifer of Fish Creek. <br />Subsidence impacts to eround water quality <br />The mine predicts that subsidence fracturing could cause a new hydraulic connection between <br />bedrock units with different quality. However, the applicant states that monitoring data <br />recorded does not indicate any substantial intercommunication of bedrock or alluvial <br />aquifers. <br />Compliance with Basic Standards for Ground Water <br />(Re¢ulation 41 of the Colorado Water Ouality Control Commission} <br />Section 4.05.13(1) of the Regulations require the establishment of one or more ground water <br />points of compliance (wells) for an operation which has the potential to negatively impact the <br />quality of ground water. The Wadge overburden and the Twentymile Sandstone are the two <br />aquifers most likely to be affected by the Foidel Creek Mine. The following wells serve as the <br />Foidel Creek Mine's ground water points of compliance: 97013TM (Twentymile sandstone), <br />008-77-58 (Wadge overburden), 008-AU3 (Fish Creek alluvium), and 008-AT-1 (Trout <br />Creek alluvium)9. The mine's annual hydrology reports contain long-term data from these <br />wells. These data show the Foidel Creek mine is in compliance with the Basic Standadds for <br />Ground Water at the ground water points of compliance. <br />Surface water <br />Several possible effects on the surface water system have been identified. <br />Discharge of mine inflow water to surface water drainages <br />Mine water dischazged to the surface water system will increase the conductivity, total <br />dissolved solids (TDS), sulfate, and iron concentrations in the streams receiving the <br />dischazge. Total suspended solids, SAR, and pH could also increase due to these discharges. <br />SAR may reach up to 6.2 in Fish Creek and 3.0 in Trout Creek. Sulfate and conductivity <br />impacts are predicted for various segments of the stream system to be affected. TR-32 <br />approved a plan that will allow the mine to dischazge considerable volumes of degraded <br />9 Permit Revision 6 Findings <br />14 <br />