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r~ <br />u <br />Introduction <br />This report has been prepared for the Colorado Department of Minerals and Geology, DMG, in <br />response to Stipulation 12 of Powderhom Coal Company's, PHCC, Mining and Reclamation Permit <br />No. C - 81 - 041. This stipulation requires the submission of an amtual report detailing the results <br />of PHCC's subsidence monitoring inspections. This report contains descriptions of the local terrain, <br />geology, mining practices and details of the surface subsidence inspections. <br />ToRographv <br />PHCC operates the Roadside North and South Portals located 4 miles northeast of Palisade <br />Colorado. The surface terrain is typical for an acid mountainous region with moderately sloping hills <br />giving way to massive sandstone cliffs. Vegetation is limited to various grasses, sagebrush, <br />saltbrush, and a small population ofpinyon-junipers. <br />Geoloev <br />In the neaz vicinity of the mine property the rock strata aze composed of three formations; the Mt. <br />• Gazfield Formation, the Hunter Canyon Formation and the Wasatch Formation. <br />The most important fom~ation is the Mt. Gazfield Formation because it contains three coal seams <br />of economic significance. These seams aze the Palisade, the Cameo, and the Carbonera seams. <br />The Palisade Seam is 3 ft. to 4 ft. thick near the abandoned Midwest mine and rapidly thins to the <br />west, south and east. The Cameo Seam overlies the Palisade Seam by 400 ft. to 450 fr. and is <br />currently the only seam being mined in the immediate area. The Cameo Seam ranges in thickness <br />from less than 5 ft. [o over 10 ft. and is the thickest in the north western parts of the property. The <br />Carbonera Seam overlies the Cameo Seam by 38 ft. to 93 ft. and is characteristically aseries of <br />detached seams rather than a single seam. The remaining 200 ft. to 400 ft. of the Mt. Garfield <br />Formation consists of interbedded to laminated carbonaceous silty, fine to very fine grained <br />sandstones and carbonaceous sandy siltstones. <br />Overlying the Mt. Garfield Formation is the Hunter Canyon Formation. It consists of massive brown <br />- buff and gray sandstones and soft gray shale and ranges from 375 ft. in the west to 1,400 ft. in the <br />east. <br />• Page 1 <br />