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West Elk Mine <br />Subsidence should not result in the draining of saturated alluvium or soils that support the <br />riparian and wetlands associated with Minnesota and Dry Fork. As discussed extensively in <br />several portions of Section 2.05.6 (6) and Appendix 60B, subsidence cracks within the alluvium <br />and soils are not anticipated to occur where the thickness of these units exceeds 10 feet. <br />Additionally, the materials supporting the wetlands consist of fine grained materials with clay <br />and silt sized particles that aze expected to heal any subsidence cracks within the soils, thus <br />preventing the diversion of subsurface water flows. <br />Changes in gradient in stream channels may result in increased ponding of water in low lying <br />areas and should encourage increases in ripazian and wetlands vegetation. If ponding does occur <br />and is not determined to create a hazard to the public, no additional mitigation is proposed. <br />However, if the ponding creates hazazdous conditions, the structure creating the ponding may be <br />breached or a bypass channel built. The mitigation work will only be accomplished after the <br />appropriate permits are obtained. Ponding resulting from mining related subsidence that is <br />allowed to remain will most likely result in an increase in rushes, sedges, water-tolerant grasses, <br />and willows. <br />If subsidence of existing Dry Creek wetlands raises the water table to a point where the wetlands <br />are in danger of destruction, the CDMG and Forest will be notified and appropriate actions be <br />taken. These actions may include excavating the portion of the channel that has created the <br />damming effect on the wetlands. No action may be appropriate where the ponding would result <br />in an overall increase in wetlands and creation of habitat that would benefit waterfowl and other <br />• wildlife. <br />If subsidence in the area of Dry Creek wetlands creates a change in the gradient that would result <br />in a lowering of the wetland water table, modifications to the stream channel to stabilize the <br />water table may be necessary. The mitigation efforts may include the construction of rock dams <br />or weirs that would act as impediments to stream flow and result in the re-establishment of the <br />wetland water table levels. The Best Currently Available Technology will be used to restore the <br />water levels of the wetlands if necessary and only implemented after obtaining approval from the <br />appropriate agencies. <br />If surface activities are proposed in riparian areas, the effects on riparian and wetland <br />resources would be evaluated at that time. <br />Wet Meadows <br />Wet meadow vegetation communities aze identified by open subirrigated areas occurring along <br />major drainages as inclusions in riparian azeas above 2,100 m (7,000 ft.) and as openings in brushy <br />or forested areas at elevations above 2,400 m (8,000 ft.). Wet meadows are occupied by herbaceous <br />species, especially those adapted to continuously moist or subirrigated conditions, such as sedges <br />(Carex sp.) and false hellebore (Veratrum californicum). <br />Wet meadow locations in the study area occur primarily in the upper drainage of the Dry Fork of the <br />Minnesota Creek in the vicinity of the Cow Camp, on flat areas of the West and East Flatirons, <br />along the upper reach of Deep Creek, and as very small, isolated azeas in the aspen forest near <br />2.04-/44 RevisedNwember 1004 PR70 <br />