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The Applicant Violator System (AV S) was queried on May 3, 2005 and again on February 28, 2006. <br />The Division recommends approval for the permit revision. The proposed decision to approve the <br />revision was issued on February 28, 2006. <br />Description of the Environment <br />The Yoast Mine plan azea is located approximately 8.5 miles southeast of the town of Hayden, and is <br />positioned between three existing coal-mining operations. The Yoast Mine plan area is <br />approximately 4 miles southwest of the Seneca II Mine, 3.5 miles east of the Seneca II-W mine, and <br />one mile west of the reclaimed Grassy Gap Mine. See Figure 1 for further detail. The mining azea is <br />located between Sage Creek and Grassy Creek and is found on USGS Mount Harris and Dunkley <br />maps. <br />Coal-mining operations have ceased at the Yoast Mine and reclamation is the only activity continuing <br />at the site. Mining occun•ed in two separate areas, and in the neck pit connecting the two areas. <br />During the first five-yeaz permit term, mining was developed in Section 17 of Township 5 North, <br />Range 87 West. Mining during the second and third terms occurred in Sections 17, 18,19, 20, 29, <br />and 30. <br />Geology and Toao~raphv <br />The Yoast permit area is located within the Wyoming Basin Physiographic Province. Elevations <br />within the permit area range between 6530 feet along the northern end of Haul Road Aand 7980 feet <br />at the summits of ridges within the southeastern portion of the proposed permit area. Slopes range <br />from 1° in Scotchman's Gulch to 100° at isolated sandstone bluffs. The terrain is characterized by <br />broad west and northeast facing moderately sloping benches and ridges that are deeply incised, and <br />barren, brush covered, southwestward facing cliffs where the more resistant sandstone outcrops. The <br />long, sloping landforms of these areas roughly coincide with the strike and dip of the underlying <br />bedrock. <br />The permit azea is dissected by several small, ephemeral drainages which flow into two principal <br />stream systems; Sage Creek on the southwest, Grassy Creek on the southeast. A detailed discussion <br />of the Yoast surface water system is presented in Tabs 7 and 16 of the permit application package. <br />The Yoast permit azea is in the Williams Fork Mountains, within the southeastern synclinal portion of <br />the Sand Wash structural Basin of northern Colorado and central Wyoming. The stratigraphy of the <br />permit area is illustrated in Figure 2. <br />The coal seams to be mined are the Wadge and the Wolf Creek. These seams are contained within the <br />Middle Coal Group, an interval of interbedded sandstones, sandy shales, shales and coal within the <br />Williams Fork Formation. The Middle Coal Group also contains the Lennox Coal seam, which is <br />non-commercially mined in the Yoast mine. Above the Middle Coal Group is the Twentymile <br />Sandstone, a 100-200 foot thick fine-grained, massive sandstone. The upper unit of the Williams <br />Fork Formation, which contains the Upper Coal Group ofthe Mesaverde group, consists oflayers of <br />sandstone, sandy shale, shale, and coal. The thickness ofthis unit varies from approximately 200 to <br />Yoas[ Mine 10 February 28, 2006 <br />