2008-08-15_PERMIT FILE - C1982056A (4)

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RESPONSE • The mine portals aze located in the NE`/o of the NE'/< of Section 32, TSN, R86W, Routt County, Colorado. Currently, these portals provide the primary openings to the mine for men and materials, utility services, and ventilation. Additionally, another portal was driven northeast of the original portals. This porta- provides access for men, equipment, and supplies into the mine. This portal is shown on Map 23, Mine Plan. Other openings into the mine include the Rock-Dust, Fish Creek, and 10-Right boreholes; the 7-North Escape Shaft; and the Eastern Mining District (EMD), NW Mains, 18-Right, and 6-North Mains ventilation shafts and associated utility boreholes. These facilities are shown on Maps 24, Surface Facilities and Freshwater Systems, and 26, Fish Creek Borehole Area Facilities and Access Road. Surface disturbances are discussed under the response to 2.05.3(3) below. Given the long history of mining on the site, disturbance boundaries are mazked by a variety of mazkers including steel fence-posts, surveyor markers, fiberglass or steel roof bolts, and steel rebaz, all of which are identifiable by their orange color or by orange paint on the top one-foot of the marker. Production of coal began from the portal slopes. A set of entries were driven towazd the north (ls` Main North). The ls` Main North was developed approximately 8,000 feet to the north. Once this initial development was completed, the North Mains were angled to the west and driven to the north permit boundary. At a point approximately 1,850 feet north of the portals, a new set of mains (15' Main West) was tamed off toward the west and were developed approximately 4,700 feet. Approximately 500 feet to the north of the 1~' Main West a second set of mains was driven. These mains were developed approximately 2,700 feet to the west. During the initia12,700 feet, the mains typically consist of six entries. Depending upon conditions, the number of entries may vary, up to a maximum of seven. Once development progressed to this point, the 6-7 entries were necked down to a three-entry gate road system for the remainder of the panel. A set of sub-mains were driven from 1 s` Left heading and extend approximately 3,000 feet to the south. These sub- • mains consist of 5 entries and the gate roads for Panels 7 through 9 were developed from them to the west. These sub-mains are shown as ls` South Sub-mains on Map 23. The first set of 6 longwall panels were developed to the west from ls` Main North. These panels extend until they reach either of two anticipated faults or until the 25 degree angle-of-draw line from the panel reaches the buffer zone of Fish Creek, whichever comes fast. An estimated 12.3 million tons were recovered from this fast block of Longwall panels. In order to explore and assess the fault zone on the west end of the panels, TCC wishes to extend the 1 s` 2"a and 3'a Left entries beneath the Fish Creek AVF. These entry extensions will be similaz in nature to the previously approved 2"a West Main entries, which were identified in the 1986 Findings of Compliance Document as having no potential adverse impacts upon the AVF. This detemunation is fiuther supported by a Wilson Pillaz Stability Analysis which yielded a safety factor of 2.2 for the anticipated 35x 80 foot pillar design of the proposed extensions. TCC does not anticipate any major inflows to be encountered during the proposed extensions, but should excessive inflows be encountered, TCC will seal the affected entry extension. TCC also plans to partially extend Panels 5 and 6 beneath the designated Fish Creek AVF. While extension was not contemplated in the original Foidel Creek mine plan, mining experience indicates that subsidence associated with longwall extraction beneath the designated AVF area will not result in significant surface impacts. In order to objectively assess potential impacts on the designated AVF due to proposed panel extension, TCC completed subsidence projections and evaluated related effects. The subsidence projections aze based on existing available subsidence data for TCC's ongoing longwall operations, and reflect an increase in panel width for Panel 6, from 625 feet (current panel width) to 850 U TR06-52 2.05-12 05/16/06