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<br />-z- <br />Rule 2.0-5.6(61 - Subsidence <br />The appllcation includes a narrative discussion of subsidence-related concerns <br />in Section 4.5.5, and a technical projection of the anticipated subsidence due <br />to the proposed five year permit's mining activities, within Appendix 4.5-1. <br />The application is complete in its response to the requirements of <br />Rule 2.05.6(6), however, my preliminary review has determined several <br />potential major inadequacies. The technical projection of subsidence <br />theorizes a mechanism which limits subsidence generation to gob formation on a <br />panel by panel basis. No consideration is given to potential stoping of gob <br />materials downdip into subsequent lower panel levels. Considerable <br />elaboration upon the anticipated mechanism of subsidence will be necessary <br />before the appllcation can be considered adequate. Secondly, I am concerned <br />that much of the area of projected significant vertical subsidence (14' <br />maximum) is comprised of steep sloped ridgetop area, which might be subject to <br />significant secondary mass movement phenomena, as a result of subsidence <br />disruption. It will 6e necessary for the applicant to prepare feasible <br />methods of detection and mitigation, 1n order to assure prevention of material <br />damage to the affected and adjoining permit areas. I also believe that a <br />significantly more complex subsidence monitoring program will be necessitated <br />by the above concerns. <br />Rule 2.06.4 - Special Categories of Mining-Steep S1oDe Mining <br />Portions of the permit area appear to qualify as steep slope mining areas. As <br />discussed under Rule 2.05.6(6), above, projected areas to be subsided during <br />the first five year permit period probably constitute steep slope mining <br />areas. Rule 2.06.4, however, does not require a specific response, but rather <br />requires compliance with the performance standards within Rule 4.27 for any <br />area which qualifies as steep slope mining. Compliance with Rule 4.27 will be <br />judged during adequacy review, following a determination of completeness. <br />The appllcation does not contain a request for a variance from approximate <br />original contour restoration requirements for steep slope mining. <br />/ep <br />Doc. No. 0129 <br />