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NEW ELK COAL <br />COMPANY <br />February 26, 2014 <br />Mr. Leigh Simmons <br />Division of Reclamation, Mining & Safety <br />1313 Sherman Street, Room 215 <br />Denver, CO 80203 <br />Re: New Elk Mine Permit C- 1981 -012 <br />Technical Revision TR -69 <br />Dear Mr. Simmons: <br />Technical Revision 69 (TR -69) has been prepared to address design <br />criteria for RDA Clean Water Diversion Ditch D -55. As a result of <br />Notice of Violation, CV- 2013 -09, the ditch was re- graded to restore <br />positive drainage along all sections of the ditch and meet the flow <br />requirements for a 100 - year /24 -hour storm event. <br />The approved design for the diversion structures can be found in <br />Exhibit 20 Refuse Pond Design and Certification. The section Contour <br />Ditches addresses the design for temporary diversion ditches as the <br />refuse lifts incrementally advance up the slope of the valley fill.and <br />predicts reduced flows as successive ditches continue to move up <br />contour with reduced run -off area. "In all cases the ditched was <br />assumed to have a triangular shape with 3H:1V side slopes ". Further, <br />the ditches were to "roughly follow existing ground contour" and <br />"classified as channels with a mild slope and the flow will be <br />subcritical" and "it will not be necessary to provide riprap protection ". <br />122250 Hwy 12 PHONE (303) 300 -8708 <br />Weston, CO 81091 Fax ((719) 868 -0044 <br />E -MAIL gsmithn @newelkcoal.com <br />