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Descriation of the Environment <br />Climate <br />The climate at the Edna Mine is typical of semi-arid steppe regions with more than half of <br />the annual precipitation (16 inches) falling as snow. The temperatures are cool, from 61 <br />F average mean temperature in August, to a cold 18 F average mean in February. <br />Regional winds aze from the west. Local topography affects both precipitation and wind <br />direction. <br />Geoloey <br />The Edna Mine is geographically situated between the drainages of Oak Creek on the east <br />and Trout Creek on the west. Topographically, the permit area is dominated by a <br />north-south trending ridge line. A steep east-facing escarpment extends to Oak Creek, <br />with a more gentle west-facing dip slope from the ridge line west to Trout Creek. <br />Elevation of the azea varies from 7,000 to 7,600 feet. <br />Except for surficial deposits, only the coal beazing Cretaceous Mesaverde Group outcrops <br />in the permit area. The Williams Fork Formation and the Iles Formation together <br />comprise the Mesaverde Group. The Williams Fork Fornation is sepazated from the <br />lower Iles Formation by the massive Trout Creek Sandstone Member, the top of which <br />forms the upper limit of the Des Formation. The coals to be mined at the Edna Mine are <br />all situated within the Williams Fork Formation, approximately 150-225 feet above the <br />Trout Creek Sandstone. The "Middle Coal Group" of the lower coal bearing member <br />includes, in ascending order, the Wolf Creek, Wadge, and Lennox coal seams. The <br />Lennox and Wedge seams were mined in the West Ridge Area. The Moffat pits will <br />recover the Wadge seam only. <br />The major portion of the Edna Mine is located on the eastern limb of the Twentymile <br />Park Syncline, the axis of which trends northwest from the southernmost boundary of the <br />permit area through West Ridge. Two minor faults occur in the Moffat Area of the mine <br />site. <br />Landscape chazacter in and near the Edna Mine results mostly from moderate folding of <br />strata followed by differential erosion of interbedded resistant and non-resistant layers of <br />various thicknesses. The southern portion of the permit area, West Ridge, consists of <br />large areas of previously strip-mined land characterized by spoil ridges from a dragline <br />operation conducted prior to enactment of the Surface Mining Control and Reclamation <br />Act (SMCRA). <br />Ground Water <br />Monitoring and on-site investigations have identified four aquifer systems at the Edna <br />Mine. These units are: 1) Trout Creek Sandstone, 2) Wadge Coal and overburden, 3) <br />Edna Mine 4 Permit Renewal No. 4 <br />