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DIVISION OF RECLAMATION, MINING AND SAFETY <br />Department of Natural Resources <br />1313 Sherman St., Room 215 <br />Denver, Colorado 80203 <br />Phone: (303) 866 -3567 <br />FAX: (303) 832 -8106 <br />w4m,r������������ <br />COLORADO <br />ID IV I S I O N O F <br />RECLAMATION <br />MINING <br />SAFETY <br />January 17, 2013 John W. Hickeniooper <br />Governor <br />Mr. Tony Tennyson Mike King <br />Executive Director <br />Colowyo Coal Company <br />5731 State Hi wa Loretta E. Pineda <br />h <br />g y 13 Director <br />Meeker, CO 81641 <br />Re: Colowyo Mine, Permit No. C- 1981 -019, TR -98 Adequacy <br />Dear Mr. Tennyson: <br />Your technical revision application TR -98 (revising the West Taylor Fill temporary spoil pile design) was <br />considered complete for the purposes of filing on December 27, 2012. <br />The Division has reviewed your revision application and we have some issues to address: <br />• Two scenarios within the geotechnical analysis by Shannon &Wilson did not meet the minimum required <br />factor of safety, (FS) of 1.5 as per Rule 2.05.3(6). These correspond to Case 2a and Case 2c. Please <br />explain how long -term stability is achieved in relation to the Division's minimum requirements for slope <br />stability of a temporary excess spoil pile. This explanation may include an additional slope stability <br />analysis regarding the temporary excess spoil fill showing that with revised input parameters (more <br />conservative than the average values but less conservative than the "low bound" values used previously) <br />the proposed excess spoil pile will meet the Division's minimum requirements of a 1.5 FS. <br />• Shannon &Wilson's analysis does not address the fact that some of the proposed excess spoil would <br />overlay an area of highwall mining. Please address the potential impact of the additional load from the <br />proposed excess spoil fill on the excavated sections from highwall mining as well as the integrity of the <br />proposed excess spoil fill. <br />• Please add information to the appropriate text and to Map 45 showing how drainage from the temporary <br />spoil pile will drain to the pit. <br />When these issues are resolved or within 60 days of completeness (February 25, 2013), whichever comes first, a <br />proposed decision approving or denying this application will be issued. <br />Please contact me (extension 8113) if you have any questions. <br />Sincerely, <br />Robert Zuber, P.E. <br />Environmental Protection Specialist <br />Office of Office of <br />Mined Land Reclamation Denver • Grand Junction • Durango Active and Inactive Mines <br />