2013-02-01_REVISION - C1981041 (8)

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could be repaired by shimming under the legs or replacing deformed members, which the operator indicated could be done without disruption of service. Mining beneath the powerline was to be limited to development mining with no secondary extraction, resulting in an extraction rate of 49 %. No definitive statement from the powerline owners documenting that potential worst case subsidence damage to the powerline could be repaired without disruption of service was ever submitted. However, South Portal mining operations ceased in 1997, prior to extension of workings to within the subsidence angle of draw associated with the powerline. No further mining within the permit area is proposed or approved. The South Mine Portals were sealed in 2000, and portal entries out -by the seals were backfilled in 2007. The possibility of resumption of mining under Permit C -81 -041 is essentially nil, and would at minimum require approval of a major permit revision. Stipulation No. 22, previously attached to the permit, had required the operator to submit specific written documentation from the powerline owners prior to mining within the subsidence angle of draw associated with the powerline. Due to the fact that coal extraction operations have ceased and the portals have been sealed and backfilled, the Division finds that Stipulation No. 22 is no longer necessary or applicable, and the stipulation was removed with RN -5 approval. The Division finds the subsidence control plan, as presented by Powderhorn Coal Company within the permit application document, to be in compliance with the subsidence - related regulations of Rules 2.05.6(6) and 4.20. On October 31, 2007 the Division issued a proposed decision to approve a Release from Liability of Areas Overlying Underground Workings (SL -3). Upon final approval of SL -3, reclamation liability would be released on approximately 7,294 acres of the permit area, which currently (November 9, 2007) encompasses 10,310 acres. Over 2000 acres of land underlain by Permit C -81 -041 underground workings are included in the area of proposed liability release; remaining lands proposed for release were neither undermined nor affected by surface disturbances or facilities associated with Permit C -81 -041. Please refer to the Division's October 31, 2007 Proposed Decision and Findings document for SL -3, for further details. XIIL Operations on Alluvial Valley Floors The permittee'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 three separate areas where alluvial valley floors must be assessed: 1. The surface facilities area and adjacent areas at the Roadside North and South Portals, and Unit Train Loadout (UTL); 2. The Cottonwood /Rapid Creek drainages and adjacent areas which will be undermined by the Roadside mine; and 3. The Colorado River Alluvial Valley Floor. 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 irrigated 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 51