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Description of the Environment <br />li ate <br />The climate at the Edna Mine istypical ofsemi-arid steppe regions with more than half of the annual <br />precipitation (16 inches) falling as snow. The temperatures aze cool, from 61 °F average mean <br />temperature in August, to a cold 18 °F average mean in February. Regional winds are from the west. <br />Local topography affects both precipitation and wind direction. <br />eo 0 <br />The Edna Mine is geographically situated between the drainages of Oak Creek on the east and Trout <br />Creek on the west. Topographically, the permit azea is dominated by a north-south Vending ridge <br />line. A steep east-facingescarpment extendsto Oak Creek, with a more gentle west-facingdip slope <br />from the ridge line west to Trout Creek. Elevation of the azea varies from 7,000 to 7,600 feet. <br />Except for surficial deposits, only the coal bearing Cretaceous Mesaverde Group outcrops in the <br />permit area. The Williams Fork Formation and the Iles Formation togethercomprise the Mesaverde <br />Group. The Williams Fork Formation is separated from the lower Iles Formation by the massive <br />Trout Creek Sandstone Member, the top of which forms the upper limit of the Iles Formation. The <br />coals to be mined at the Edna Mine are all situated within the Williams Fork Formation, <br />approximately 150-225 feet above the Trout Creek Sandstone. The "Middle Coa] Group" of the <br />lower coal bearing member includes, in ascending order, the Wolf Creek, Wadge, and Lennox coal <br />searns. The Lennox and Wadge seams were mined in the West Ridge Area. The Moffat pits will <br />recover the Wadge seam only. <br />Most of the permit area of the Edna Mine is located on the east limb of the Twentymile Pazk <br />Syncline, the axis of which trends noRhwest from the southernmost boundary of the permit area <br />through West Ridge. Two minor faults occur in the Moffat Area of the mine site. <br />Landscape chazacter in and near the Edna Mine derives from differential erosion of interbedded <br />resistant and non-resistant layers of various thickness which have been folded moderately. The <br />southern portion of the permit area, West Ridge, consists of large areas of previously strip-mined <br />]and characterized by spoil ridges from a dragline operation conducted prior to enactment of the <br />Surface Mining Control and Reclamation Act (SMCRA). <br />Groundwater <br />Monitoring and on-site investigationshave identified four aquifer systems at the Edna Mine. These <br />unitsaze: 1) Trout Creek Sandstone, 2) Wadge Coal and overburden, 3) Quaternary alluvium, and <br />4) replaced spoils. The bedrock units are thought to be hydrologicallydiscontinuouswith each other <br />because of the relatively impermeable nature of the intervening strata. <br />Edne Mine A Pertnii Renewal No. J <br />