2007-07-30_GENERAL DOCUMENTS - C1981041

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indicates could be done without dismption of service. Mining beneath the powerline would be limited to development mining with no secondary extraction, resulting in an extraction rate of 49%. As of August 2003, no definitive statement from the powerline owners documenting that potential worst case subsidence damage to the powerline could be repaired without disruption of service has been submitted. Mining has ceased and no further mining within the permit area is proposed or approved. Resumption of mining is unlikely, and would require approval of a major permit revision. For these reasons, it is unlikely that the powerline will be undermined. The following stipulation is unlikely to be triggered, but is retained as a precautionary measure. Stipulation No. 22 AT LEAST 120 DAYS PRIOR TO INITIATION OF COAL EXTRACTION WHICH COULD POTENTIALLY CAUSE SUBSIDENCE DAMAGE TO THE 345 KV RIFLE-SAN JUAN POWERLINE, THE PERMITTEE WILL SUBMIT WRITTEN STATEMENTS FROM THE OWNERS OF THE POWERLINE WHICH INDICATE THAT POTENTLAL WORST CASE SUBSIDENCE DAMAGE TO THE POWERLINE COULD BE REPAIRED WITHOUT DISRUPTION OF SERVICE. NO MINING WHICH COULD AFFECT THE POWERLINE BASED ON PROJECTED SUBSIDENCE ANGLE OF DRAW SHALL OCCUR PRIOR TO DMG'S WRITTEN NOTICE OF COMPLIANCE WITH THIS STIPULATION. With the acceptance of Stipulation No.22, the subsidence control plan, as presented by Powderhom Coat Company within the amended application documents, is found to be in compliance with the subsidence-related regulations of Rules 2.05.6(6) and 4.20. XIII. Operations on Alluvial Vallev Floors The pertnittee's alluvial valley floor investigations in Section 2.06.8 of Tab 21, Volume 6, of the application have been reviewed for compliance. There are two separate areas where alluvia! valley floors must be assessed: 1. The surface facilities area and adjacent areas at the Roadside North and South Portals, and Unit Train Loadout; and 2. The Cottonwood/Rapid Creek drainages and adjacent areas which will be undermined by the Roadside mine. Drainages in the North Portal mining area are characterized by steep sided canyons with deeply incised channels, limited areas of alluvial deposition, and no flood inrigated or subirrigated agriculture. Headwaters for these drainages are at relatively low elevations in the Book Cliffs, and the streams exhibit intermittent or ephemeral flow regimes. Insufficient surface water availability and saline soils eliminate Coal Creek, Jerry Creek and their tributaries from alluvial valley Floor consideration. Drainages in the bookcliffs with characteristics similar to those in the permit area are not typically developed for irrigated agriculture (OSM, June, 1985 "Reconnaissance Maps to Assist in Identifying Alluvial Valley Floors, West-Central Colorado"). Potential AVF areas within and adjacent to the permit area are addressed below. See Tab 21 of the application for further information. Permit Revision No. 3 Permit No. C-1981-041 July 30, 2007 Page 53