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RULE 2 PERMITS <br /> Underlying the Williams Fork Formation is the Iles Formation.Little data are available to describe <br /> the characteristics of the Iles Formation,principally because of its great depth. However,based on <br /> information from adjacent areas,the general characteristics of the Iles Formation can be described. <br /> The Iles Formation is continuous and can be correlated over a large area. Trout Creek Sandstone, <br /> the upper member of the Iles Formation, has been mapped to be 75 feet thick. This sandstone is <br /> easily recognized and is considered a marker bed for the top of the Iles formation. Trout Creek <br /> Sandstone is a white, fine-grained and well sorted sandstone. It is fairly uniform in thickness in <br /> the general area. <br /> Beneath the Iles Formation lies the Mancos Shale. The Mancos Shale is a marine shale with thin <br /> interbeds of siltstones and limestones and is estimated to be over 5,000 feet thick in this area. This <br /> shale forms the base of the regional groundwater system in the area. These shales are relatively <br /> impermeable and do not store or transmit appreciable quantities of groundwater. The Mancos <br /> Shale is exposed north of the permit area and is found at depth beneath the permit site. <br /> The permit area straddles the southern limb of the Collum Syncline. The syncline is a regional <br /> structure trending in a southeast northwest direction parallel to the major geologic structure of the <br /> area in the Axial Basin. The Williams Fork and the Iles Formations are truncated north of the <br /> permit area and the Mancos Shale is exposed as a result of the regional geologic structure. <br /> Goodspring, Taylor and Wilson Creeks are tributaries to the Yampa River, a major surface water <br /> feature located some distance from the mine property. Water resources on the mine property are <br /> connected to the Yampa River only by surface water discharge and then only during periods of <br /> infrequent snowmelts and thunderstorm events. A second major surface water feature in the area <br /> is the Williams Fork River. However, the Williams Fork River, which is a tributary to the Yampa <br /> River, does not receive discharge from Wilson, Goodspring or Taylor Creeks. Instead, the <br /> Williams Fork flows into the Yampa River near the town of Hamilton. This location is far above <br /> the confluence of'the Yampa River with Milk Creek, the immediate receiving system of water <br /> from Goodspring, Wilson and Taylor Creeks. <br /> Surface and groundwater resources in the general area of the mine are limited. There is little <br /> development of resources. Those resources which are developed are limited in scope and in <br /> quantity. A few wells have been constructed into the fine grain sandstones of the Williams Fork <br /> Formation or into fractured parts of the Mancos Shale. These wells typically yield less than five <br /> gallons per minute (gpm) and their uses are limited to domestic and/or livestock supplies. Surface <br /> water development in the region is limited to irrigation and consists of both direct flow and storage <br /> rights. Most of the surface water development occurs in the valley of the Yampa River east of <br /> Craig, Colorado. However, this general area of the development is many miles from the mine <br /> property. <br /> Permit Area <br /> Groundwater on the Colowyo Mine property occurs under perched conditions in the interbedded <br /> and lenticular sandstones of the Williams Fork Formation above the coals to be mined. There is <br /> no continuous, regional groundwater system on the propeny within the straLigraphic section to be <br /> Rule 2 Permits 2.04-12 Revision Date: 12/20/19 <br /> Revision No.: TR-135 <br />