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COLORADO <br />Division of Reclamation, <br />Mining and Safety <br />Department of Natural Resources <br />1313 Sherman Street, Room 215 <br />Denver, CO 80203 <br />October 30, 2014 <br />Chris Gilbreath <br />Tri -State Generation and Transmission Association, Inc. <br />P.O. Box 33695 <br />Denver, CO 80233 -0695 <br />Re: New Horizon North Mine (Permit No. C- 2010 -089), TR -06, third adequacy letter <br />Dear Mr. Gilbreath: <br />We received your responses to our second adequacy letter for TR -06 on October 10, 2014. There are still <br />some items to be addressed before the Division can approve this revision. <br />It is unclear why there is no new SEDCAD run for the north ditch but there is one for the south ditch. Please <br />explain this apparent omission. <br />In the proposed text, on Appendix 8 page 8, it is written that erosion of ditch bed material may happen during <br />storm events and that maintenance will be required. This approach does not meet Rule 4.05.4(2)(a), which <br />states that ditches must be constructed to be stable. Also, the new version of Map 2.05.3(4)-9 indicates slopes <br />of 1 - 4% for the north channel and 5% slopes in the upper portion of the south channel; however, the <br />previous submittal (Table 2.05.3(4) -8 -2) indicates that channels with 12' width and slopes of 3% or more <br />require riprap. Please explain this apparent discrepancy. <br />If you have any questions, please contact me at 303.866.3567 (extension 8113) or Rob.Zuber@state.co.us. <br />Sincerely, <br />Robert Zuber, P.E. <br />Environmental Protection Specialist <br />1313 Sherman Street, Room 215, Denver, CO 80203 P 303.866.3567 F 303.832.8106 http: / /mining.state.co.us <br />John W. Hickenlooper, Governor I Mike King, Executive Director I Virginia Brannon, Director <br />Colo <br />'f 1876 �` <br />