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<br /> <br />J.E. Stover & Associates -29- May 31, 1996 <br />Bowie No. 2 Mine <br />87. However, the Division does believe it would be appropriate <br />to visually inspect known historic and modern landslides, <br />during the periods immediately following retreat extraction <br />in their immediate proximity. Please incorporate a <br />commitment to do so. <br />(f)(ii)(B) <br />The application proposes a method to prevent near subcrop <br />subsidence impacts, including chimney collapse and cantilever <br />failure. However, the preparer of Exhibit 15 is ambiguous in the <br />important referenced section. <br />88. The applicant should clarify the proposal. Further, <br />additional information should be provided to stipulate <br />whether the extended pillar will be unmined, or developed. <br />Obviously, at least one development room will have been <br />extracted in order to encounter the low quality coal. The <br />application should expand on this proposal to clarify the <br />approach to be implemented. <br />(f) (v) (B) <br />Monitoring <br />The application proposes to visually inspect the permit area to <br />determine whether new mass movement features have developed. If <br />new landslides are detected "they will be brought to the <br />attention of the Division". The Division will require a more <br />detailed proposal for action in the event of rejuvenation of old <br />landslides or the development of new landslides. <br />89. At a minimum the applicant will need to evaluate each <br />rejuvenated or new landslide to determine what the apparent <br />cause of the modern movement might be. If appropriate, <br />mitigative methods should be proposed to minimize hazard to <br />the mine facilities, public health & safety, and the <br />environment. <br />Exhibit 15 - Subsidence Prediction <br />The analysis presented within the application employs empirical <br />methods of prediction. The empirical methodology is based <br />largely upon the proven methods developed by Britain's National <br />Coal Board (NBC), published in 1975 as "The Subsidence Engineer's <br />Handbook". The NBC's empirically derived predictive <br />relationships were developed predominantly for subsidence above <br />longwall underground extraction. During the past two decades a <br />