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~~ -2- 5. Because the exact angle of draw was unable to be determined by the NW-1 subsidence monitoring data, an additional zone of possible subsidence beyond the limit of predicted subsidence has been identified. On Map 20, Structure Inventory, this additional zone is identified as the "500-foot barrier". For this area, please provide a subsidence survey, as described in Stipulation No. 66 and Rule 2.05.6(6)(e), as well as a subsidence control plan per Rule 2.05.6(6)(f) if necessary. 6. Question C-2 of the Division's first adequacy letter requested that all drill site and exploration hole locations be placed in the Post Mining Land Use Map No. 12. However, Rules 2.05.5(2)(a) and (c) apply to lands, disturfied by surface operations and facilities associated with underground mining activities, that are proposed to be reclaimed. The oSt definition of underground mining activities, per Rule 1.04(144), does not include exploration. nos; M,.,..~ ~~r -Z Therefore, Map 12 should be revised to include those areas proposed for reclamation that are associated with development holes (degas wells), airshafts, and their associated access roads. Exploration holes and their associated roads do not need to be included unless they have been converted to uses associated with the mining operation, such as degas wells or water monitoring locations.. 7. The narrative under Section 2.05.5, "Post-Mining Land Uses", needs to be revised to include the areas described in Item No. 6 of this letter. The narrative should follow Rule 2.05.5(2). In addition, under Rule 2.05.4(2)(c), the post-misting contour map and cross sections should be revised to include the NW-1 airshaft and 3rd North airshaft areas, and a typical road cut reclamation plan. 8. Based upon our review of the presently proposed subsidence monitoring program for the west end of the NW-3 panel, it appears that the maximum potential angle of draw that could be observed is 44 degrees. The Division recommends subsidence monitoring programs be developed to observe a maximum potential angle of 45 degrees. Please confum the maximum angle of draw that could be observed from the proposed subsidence monitoring stations located at the west end of the NW-3 panel and at the east end of the NW-2 panel. 9. The Division recommends that the proposed subsidence monitoring stations at the west end of the NW-3 panel and at the east end of the NW-2 panel be spaced 50 feet apart, rather than 100 feet apart, in the zone where the angle of draw is expected to end. At a 100 foot spacing, the degree of accuracy may be insufficient. 10. At the west end of the NW-3 panel, the 100 foot spacing corresponds to approximately 5 degrees of angle of draw, from the next to the last station to the last station. Consequently, it would appear that the degree of accuracy considered for any future items involving the angle of draw would be no more accurate than plus or minus 5 degrees. Please confum this. If monitoring stations were spaced 50 feet apart rather than 100, this degree of accuracy could be improved. Please address.