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~~OUNTAIN COAL ~ ~ ~ COMPANY~.~- west E>k Mme A Subsidiary ofP.rch Western Resources, LLC P O Box 591 5174 Highway 133 Somerset, CO 81434 (970) 929-5015 Fax (970) 929-5595 jor the South of Divide Mining Area". Additionally, MCC has reviewed the "Skyline Mine Subsidence Study, Changes in Stream Channel Characteristics and Hydraulic Parameters Related to Surface Subsidence"prepared by the Forestry Sciences Laboratory, Rocky Mountain Research Station in Logan, Utah jor the Monti-LaSal National Forest, Utah in July 1998. This paper addresses the vegetative and geomorphic changes that occurred in the perennial Burnout Canyon Creek as a result ojlongwall coal extraction mining beneath the stream. Further, we have reviewed Burnout Creek flow data collected by the Skyline Mine from 1993 to present to determine what, ij any, effects undermining the stream had on the stream flow volumes. Much ojthe flow data is available from the Monti-LaSal National Forest in the Data Adequacy volumes submitted jor an EIS initiated for the leasing of the Flat Canyon Tract adjacent to the Skyline Mine. Finally, MCC has reviewed the data the Utah Division of Oil, Gas and Mining and the Canyon Fuel Company, LLC have on the effects of longwall mining beneath the perennial East Fork ojBox Canyon Creek, Emery County, Utah by the Sufco Mine. Site Comparison ofDrv Fork and NFRF of Miller Creek As a result ojthis review, MCCfinds significant differences in the general stream morphology when comparing the Dry Fork in the SOD area with the NFRF of Miller Creek in Utah. A striking difference is noted in the overall gradient oJthe portions ojthe drainages affected by mining in • Miller Creek and those to be affected by mining SOD. The portion of the NFRF of Miller Creek undermined had a gradient of 23% while the section ojDry Creek that will be undermined has a gradient 4 %. This difference in gradient is partially responsible for the differences in the amount of alluvia[ cover present in each system. The general cross-section of the two streams is also different. The NFRF of Miller Creek has a fairly narrow channel at the bottom oja steep walled canyon with bedrock forming the majority of the channel floor and colluvium and bedrock forming the channel banks. The majority ojthe Dry Fork channel where there is less than a 1000 feet of overburden above the coal seam to be mine is incised in a thick mantle of alluvium that covers the canyon floor. The stream banks are steep and channel floor and walls are comprised mostly ojsand, silt, and clay with some exposed bedrock. The NFRF ofMil[er Creek has very little alluvial cover in the affected stream channel resulting in the stream ruxxing over large stretches ojexposed bedrock (Erik Petersen, Oral Commuxication, August 20, 2004). Most of the Dry Fork channel floor has a few feet to several feet ojalluvial cover. Specifically, in the areas ojDry Fork where the overburden is 400 to S00 feet thick over the panels to be mined, the alluvium appears to be 10 to 30 feet thick. No discussion is provided in the USGS NFRF of Miller Creek report regarding the thickness of the alluvial cover, if any, on the stream channel floor. The stratigraphy of the NFRF ojMiller Creek is presented only in a general sense. No site-specific lithology is presented to allow the reader to determine what types ojrock units are present in the areas where the creek flow went subsurface. Therefore, it maybe difficult to make meaningful comparisons between the NFRF of Miller Creek response to subsidence and the anticipated effects of subsiding Dry Fork MCC's PR-10 Figure SE Cross Section E-E', illustrates detailed lithology in the area of the west end oJpanels E2 and E3, specifically from drill hole logs of exploration holes SOM-30, SOM-C75, and SOM-57. The logs indicate the presence of claystone and shale beds several tens of feet thick, units 15