2008-03-21_PERMIT FILE - C1980007A (46)

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West Elk Mine If surface cracks were to form and if they were to intercept stock ponds or ephemeral channels, they could potentially intercept surface water. Field evidence at the Section 17 cracks, evaluation of the soft plastic shales occurring in the Barren Member above the F Seam, and theoretical subsidence stress-strain relationships discussed elsewhere in the subsidence section of the application, each strongly suggest that surface cracks would not extend to any great depth. Two factors will also tend to heal the cracks, if they were to intercept water. First, the shales of the Mesaverde Formation are known to have shrink-swell capacity. If the saturation of these shales were to be increased, they would swell and this could be expected to help heal the crack. Secondly, Mr. Jeff Hynes of the Colorado Geological Survey (1994) has stated that a greater factor in crack healing would be increases in the plasticity of the shales as water saturations were increased. Simply stated, as the shales become wetter, they soften and will squeeze into and heal the cracks. An important consideration regarding mining in the Apache Rocks, South of Divide and Dry Fork permit revision areas are potential impacts to the Minnesota Reservoir. The water rights implications of mining in the tributary area to the reservoir are discussed later in Section 2.05.6 (3)(b)(iii & viii) Water Rights. MCC has committed to maintaining a buffer zone between active mining and the dam of over 1,000 feet, which is greater than the distance utilizing the conservative angle of draw 25 degrees. With a setback of this margin, there is no risk of either a crack developing under the reservoir or aggravation of the existing structural problems with the dam as a result of MCC's mining activities: Mining of longwall Panel 13 in the B Seam occurred at a distance of approximately 700 feet from the reservoir with no adverse impacts to the structure. The additional distance for longwall Panel E9 is very conservative given that the E Seam is stratigraphically higher and, therefore, has a smaller area of influence at a given angle of draw. Wetlands Based upon inspection of conventional and infrared aerial photographs and reconnaissance-level field investigation, the wetlands in the permit area are confined primarily to manmade stockponds in the drainages. They are intermittent in nature. Very few "natural" riparian wetlands are evident. The total acreage of potential jurisdictional wetlands in the permit area is approximately 7 acres (as defined by the U.S. Army Corps of Engineers (USACE)). Field surveys conducted in August 1995 verified this estimate. An additional 2 to 3 acres lies above the LONE and 11 NE longwall panels. Field surveys in the South of'Divide permit area in 1996 found additional wetland/riparian areas along the valley bottoms within the Dry Fork and Lick Creek drainages and in association with hillside spring and seeps (refer to Section 2.04.10). Another study was conducted November 2004 shoving these additional wetland areas and is included in Exhibit 32B, Drawing 1. AlthouUh most of the wetlands are found u1 drainage channels, there are small, isolated wetlands on *he hillsides where springs and seers emerge. There are other isolated wetlands in association with landslides and slumps. In these instances. the wetlands are associated with the uppermost portion of the landslide/slump, where a relatively flat area has been created and water has tended to collect and saturate the soils. 2.06-207 Revised June 2005 PRIO: Rev. Alarch 2006: Rev. April 2006 PRIO; .May 2006 PRIO; Sep. 2007 PR12; Feb 2008 PR12