2009-05-22_GENERAL DOCUMENTS - C1981044

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subsidence is 10.5 feet. In areas where only one seam has been mined using longwall methods, maximum predicted subsidence is 7.5 feet. Further information can be found in permit Section 2.05. While the mine is in active status, BTU EC has committed to submitting results of the monitoring program at least semi- annually. Maximum total subsidence of 10 feet has been reported in the subsidence reports. The longwall panel 2 of Mine 6 was proposed to undermine the Amoco pipeline. The predicted subsidence that could occur under this zone was estimated at 10.5 feet, since this would involve one longwall panel under room-and-pillar workings. In lieu of subsiding the pipeline, the operator opted to relocate the pipeline and not conduct full extraction of the coal within 100 feet horizontally of the pipeline. This 100-foot buffer will allow for an angle of draw calculated at 19°. This plan was in agreement with the Amoco Pipeline Company and approved by the Division by Minor Revision No. 24. The operator also submitted a plan to undermine a portion of the railroad spur, the Williams Fork alluvial valley floor, the Williams Fork River, and a portion of State Highway 13. Further detail on this proposal can be located in Technical Revision No. 19. The Division approved of development mining only under these resources, with three additional subsidence monitoring locations along the highway, 1. The Division has previously found the permittee's subsidence control plan complies with Rule 2.05.6(6) and the permittee has committed to adopt all measures in order to reduce the likelihood of subsidence, prevent material damage, or mitigate the effects. The Division has previously approved the plan (4.20.1(2) and 4.20.3(1)). 2. The Division has previously found that the permittee's subsidence monitoring program complies with Rule 2.05.6(6)(c), and is designed to determine the commencement and magnitude of subsidence movements. The "B" Seam Longwall Subsidence Monitors" map submitted with the semi-annual subsidence report depicts the location of monuments to be installed and structures to be monitored within the permit and adjacent area. The results of the monitoring program will be submitted to the Division semi-annually. The monitoring program is designed to extend for a time, beyond cessation of mining in any area, consistent with the need for verification of the subsidence prediction. XI. Operations on Alluvial Valley Floors The applicant has determined that alluvial valley floors exist along both the Yampa and the Williams Fork valleys within the permit and adjacent area. This determination is based upon the fact that flood-irrigated agricultural activities are practiced on unconsolidated streamlaid deposits along both rivers. The Division concurs with this determination. The boundary of the alluvial valley floors is shown on Map 25 of the Eagle Mine Complex 35 Permit Renewal 05 C-1981-044 May 22, 2009