2016-05-04_REVISION - C1982056 (12)

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The 10 East Mid Panel Emergency Air Borehole was approved in 2015 but at the writing of this document has not been constructed. The 13 -Left Outby Utility Borehole was approved in December of 2015 and the access road and pad was constructed in early 2016 and the borehole was also drilled at that time. Physiographic Setting The permit area varies in elevation from 6,600' to 7,500' with the portal openings at 6,885' along Foidel Creek. Generally, the topography consists of gently rolling hills, dip slopes and cliff outcrops. Flatter topography is evident in the valleys of the major streams draining the area (Fish Creek and Foidel Creek), as well as along the gentle dip slopes. Prominent cliffs have formed where massive sandstone units outcrop. Geologic Setting The rock units of Twentymile Park Basin which dip 5° - 30° toward the central portion of the basin are of local significance. Normal faulting has been identified throughout the permit area, striking generally northwest to southeast, with displacement of zero to 85 feet. A reverse fault running in an arcuate line northward through the west central part of the basin shows displacement of 0 to 80 feet. Smaller lateral faults were encountered in the 9 Right and 10 Right gateroads while driving development out into the Eastern Mining District. The near surface bedrock units are composed of sedimentary rocks of marine and non -marine origin. These sedimentary rocks were formed through the transgression and regression of an epicontinental sea and are comprised of sequences of sandstones, siltstones, shales and coal. Four geologic formations exist in the vicinity of the Foidel Creek Mining Districts. They are, in ascending order, the Mancos Shale, the Iles and Williams Fork Formation of the Mesaverde Group, and the Lewis Shale. These strata were all deposited during the late Cretaceous Period. Generally, the strata dip to the center of the basin. Coal Seam Stratigraphy Three economically important coal seams, the Lennox, Wadge, and Wolf Creek coals, are located within the locally important Middle Coal Group of the Williams Fork Formation. TC is currently mining coal in the Wadge Coal Seam. The Wadge Coal seam was strip mined in CYCC's adjacent Energy Mine No. 1, Energy Mine No. 2, and Eckman Park Mines (No. C-81- 071) and Energy Mine No. 3 (C-84-062). The Wadge coal seam, in the area of the Foidel Creek Mine, is separated from the underlying Trout Creek sandstone by about 250 feet of interbedded sandstones, siltstones, shales and coals. The Wadge coal seam is separated from the overlying Twentymile sandstone by 700 feet of massive shale and interbedded sandstones, siltstones, shales and coals. Overburden depths in the current permit area range from 0 to 1,700 feet. TC also mines within the Wolf Creek Seam. TC was given approval to conduct development mining within this seam with the approval of TR83 in December of 2014. PR -10 proposes to update the mining plan to conduct development mining and longwall mining of this seam in the 5RT to 9RT longwall panels as depicted on Maps WC -23 and WC -23B dated July 6, 2015, proposed to be approved with PR -10. The Wolf Creek Coal Seam splits into four distinct Page 12 of 52