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West Elk Mine <br />If stream channels are impacted by subsidence, efforts will be made to repair the channel to ensure that flow <br />continues in the channel. If cracking, headcutting or significant channel incising occurs, MCC will evaluate <br />the channel morphology and prepare a mitigation plan. Mitigation may require the sealing of fractures, if <br />they occur in the stream channel, with bentonite/soil mixes to stop water loss, excavating ridges or high <br />areas created by subsidence within the stream channel that impede flow, and redirecting flow, if <br />necessary, back into the original channel if diverted due to subsidence. Temporary culverts in ditches and <br />streams may also be used to bridge surface cracks while the. best method to seal the fractures is <br />determined. <br />If stream courses are blocked by mining induced slide movement, MCC will use hand tools or appropriate <br />heavy equipment to reopen affected channels. The necessary permits to perform such work will be <br />obtained prior to performing mitigation. Other mitigation may include the placement of straw bale dikes <br />or silt fences below slide areas to reduce sediment loading. If ponding occurs due to rockfalls or slides <br />within the stream channels and is not detennined to create a hazard to the public, no additional mitigation <br />is proposed. However, if the ponding creates hazardous conditions, the structure creating the ponding <br />may be breached or bypass channel built. The mitigation work will only be accomplished after the <br />appropriate permits are obtained. <br />If ponding occurs within the stream channels due to differential subsidence and is not detennined to <br />create a hazard to the public, no additional mitigation is proposed. However, if the ponding creates <br />hazardous conditions, the structure creating the ponding may be breached or bypass channel built. The <br />mitigation work will only be accomplished after the appropriate permits are obtained. <br />If subsidence of existing SOD wetlands raises the water table to a point where the wetlands are in danger <br />i of destruction, the CDMG and Forest will be notified and appropriate actions be taken. These actions <br />may include excavating the portion of the channel that has created the damming effect on the wetlands. <br />No action may be appropriate where the ponding would result in an overall increase in wetlands and <br />creation of habitat that would benefit waterfowl and other wildlife. <br />If subsidence in the area of SOD wetlands creates a change in the gradient that would result in a lowering <br />of wetland water table, modifications to the stream channel to stabilize the water table may be necessary. <br />The mitigation efforts may include the construction of rock dams or weirs that would act as impediments <br />to stream flow and result in the re-establishment of the wetland water table levels. The Best Currently <br />Available Technology will be used to restore the water levels of the wetlands if necessary and only <br />implemented after obtaining approval. <br />Additional mitigation of mining impacts may be necessary if loss or diversion of flow or a significant <br />change in the stream profile will significantly impact vegetation. Efforts will be made to re-establish <br />riparian vegetation in areas negatively impacted by changes in flow locations. These re-establishment <br />efforts may include, but not be limited to, planting of new seedlings or reseeding with appropriate species. <br />The appropriate permits and approvals of plant or seed mixes will be obtained prior to performing <br />mitigation activities. <br />It is anticipated that little or no impacts to wildlife and domestic livestock uses, and their respective <br />habitat will occur as a consequence of mining-induced subsidence on the permit area. In the unlikely <br />event that subsidence effects adversely impact o,;ddlife or domestic livestock uses associated mitigation <br />measures will focus on returned disturbed areas to a capability and land use(s) which existed prior to <br />mining. These mitigation measures may include, but not be limited to, repairs of surface cracks that are <br />deemed dangerous to human, wildlife, or livestock. The repairs of the cracks may include backfilling <br />with available native soils, gravels, concrete block, etc. Livestock fences damaged by mining related <br />activities will be repaired as soon as possible. <br />2.05-171 Revised June 200.1 PRIG, Rev. March 2006; hlaj, 2006 PR10. Yov. 2006TR107,.9pri12007TR108;Sep. 2007 PR12; Feb. 2008 PR-12