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7 iiiiiii~tuiiiiiii STATE OF COLORADO DIVISION OF MINERALS AND GEOLOGY Deparimenl of Natural ReKOUrces 1 313 Sherman $t., Room ? 15 Denver. Culorado BO:G) Phone 14031 A66J 567 FA\~ 170 t1 A32-A106 February 3, 1998 ~~ DEPARTMENT OF NATURAL RESOC.TRCES Roy Rome Governor Ms. Christine Johnston 1„""'' `°`hnr'"' E~ecume Direiurt Mountain Coal Company hu~h~r~ a Font P.O. Box 591 Diri9ipn Dire,~r Somerset, Colorado 8143 Re: Technical RevisionNo. 83; Review ofMCC Responsesto Adequacy Comments; West Elk Mine; Permit No. C-80-007 Deaz Ms. Johnston: The Division has reviewed Mountain Coal Company's responses to our adequacy review letter dated December 18, 1997. The Division has the following remaining comments concerning the adequacy of the 7R-83 submittal. 1. - 3. Responses accepted. 4. MCC notes that, based on the proposed energy dissipation plan, erosion of the 10' section of natural ground adjoining the West Fork of Sylvester Gulch is not expected. The Division will accept this response, but would caution MCC that should erosion occur, it may be a compliance issue. No further response is required. MCC provided a brief description of the routing structures between the treatment structures, but has not provided a map or drawing showing their locations. This response is acceptable, but the Division will monitor the stability of the area, and if problems are observed, MCC may be required to provide a map or drawing showing the location of the underground piping between structures. No further response is required. Response accepted. The issue of utilizing large capacity sumps is under review with TR#80. The Division understands that the Mine Dewatering and Treatment Facilities proposed with this technical revision would be a beneficial water management practice. As stated in the TR#80 submittal, the NE Panels sealed sump will have a proposed estimated storage capacity of more than 130 million gallons and the estimated time to fill the NE panels sealed sump is just over 1 year. At the time that TR#80 was submitted, the NE longwall panels had not yet been mined. Have the NE longwall panels been mined since the time that TR#80 was submitted, and if so, is water currentiv being stored in the proposed NE Panels sealed sump? Please specify the maximum anticipated volume of water to be stored at any given time in the NE Panels. Also specify the duration of storage. Does MCC anticipate that the NE Panels will be a permanent storage reservoir, or is it MCC's intent to completely dewaterthe NE Panels seated sump? Please provide the above information so that the Division can finalize its review of the TR#83 application submittal.