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by surface methods on the dip slopes, where overburden thickness allows for economic extraction within
<br />Twentymile Pazk azound its mazgins, and where folding has elevated a major coal seam within the basin,
<br />Foidel Creek Mine is currently the only active underground operation within Twentymile Park. The mine
<br />is a longwall operation, using continuous miners for entry and development work only. The permit azea
<br />encompasses approximately 22,694 acres. This permit revision (PR-06) does not propose to enlarge the
<br />permit boundary or disturb new azeas on the land surface, although it does propose new acres of surface
<br />disturbance.
<br />USGS Quadrangle Wraps of Milner and Rattlesnake Butte cover the majority of the permit azea Disturbed
<br />areas of the mine include the main surface facilities area along Foidel Creek and numerous smaller
<br />outlying facilities. These mine-related facilities result in 460 total disturbed acres. The main mine facilities
<br />lie in Sections 29, 31, 32, TSN, R86W of the 6th Principal Meridian and are located in, and adjacent to, a
<br />strip pit excavated originally by Colorado Yampa Coal Company's (CYCC) surface mining operation (No.
<br />C-81-071). Other facilities currently within the permit azea, but sepazate from the main portal facility area,
<br />include: the Fish Creek Borehole (FCB) facility, the Southwest ventilation facility (SW vent), the Eastern
<br />Mining District ventilation facility (EMD vent), the Eastern Mining District dewatering facility (EMD
<br />borehole), the Sandstones substation and North Escape Shaft, the Fish Creek Tipple (FCT) facility, the
<br />Eastern Mining District grout hole pad, and the Northern Mining District (NMD) vent shaft.
<br />The Fish Creek Borehole (FCB) is located on Fish Creek approximately 2 miles northwest of the main
<br />facility area in Section 25, TSN R87W. It consists of 2 dewatering boreholes, an inactive ventilation shaft,
<br />3 treatment ponds, associated roads, a substation, a utility building, and water treatment equipment. The
<br />SW vent was reclaimed in 1996 and is located in Section 36, TSN R87W. The EMD vent facility is
<br />located in Section 14, TSN R86W and consists of two venfilation shafts (intake air and return air), intake
<br />air heating unit, associated buildings, powerlines, and fuel tank. The EMD borehole disturbed azea is
<br />located in Section 21, TSN R86W and consists of a small pump building, a buried water return line and
<br />topsoil stockpiles. The Sandstones substation in Section 20, TSN R86W no longer serves as a power drop
<br />to the mine. The neazby North Escape Shaft has no facilities but exists as a completed 3 foot diameter
<br />shaft to be used only as an underground emergency extraction point for miners. The NMD vent shaft
<br />consists of associated buildings and a powerline.
<br />The Fish Creek Tipple.(FCT) facility is located approximately 5 miles northeast of the main portal area in
<br />Section 2, TSN R86W, about 7 miles downstream on Fish Creek from the FCB facility. It was originally
<br />permitted sepazately under permit No. C-81-036 but since has been incorporated into the Foidel Creek
<br />permit No. C-82-056. It consists of a rail loadout, crushing and screening equipment, conveyors, stockpile
<br />azeas, and a sediment control system of ditches and one pond. The FCT facility has been idle since Energy
<br />Mine No. 3 (No. C-84-062) completed mining in 1986, and is currently inactive.
<br />Locally significant are the rock units of Twentymile Park Basin which dip 5 to 30 degrees north toward the
<br />central portion of the basin. Normal faulting has been identified throughout the permit azea, striking
<br />generally northwest to southeast, with displacement of zero to 85 feet. A reverse fault running in an
<br />arcuate line northward through the west central part of the basin shows displacement of 0-80 feet. Smaller
<br />lateral faults were encountered in the 9R and l0R gateroads while driving development out into the
<br />Eastern Mining District.
<br />The neaz-surface bedrock units aze composed of sedimentary rocks of mazine and non-mazine origin.
<br />These sedimentary rocks were formed through the transgression and regression of an epicontinental sea
<br />and are comprised of sequences of sandstones, siltstones, shales and coal. Four geologic formations exist
<br />in the vicinity of the Eastern Mining District. They are, in ascending order, the Mancos Shale, the Iles and
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