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STATE OF COLORADO <br />DIVISION OF RECLAMATION, MINING AND SAFETY <br />Department of Natural Resources <br />1313 Sherman St., Room 215 <br />A&-4�4k <br />Denver, Colorado 80203 <br />C O L O R A D O <br />D 1 V 1 5 1 o N O F <br />Phone: (303) 866 -3567 <br />RECLAMATION <br />FAX: (303) 832 -8106 <br />MINING <br />SAFETY <br />January 7, 2014 <br />John W. Hickenlooper <br />Governor <br />Mr. Chris Gilbreath <br />Mike King <br />Tri-State Generation and Transmission Association, Inc <br />Executive Director <br />P.O. Box 33695 <br />Loretta E. Pineda <br />Denver, CO 80233 -0695 <br />Director <br />Re: New Horizon North Mine, Permit No. C- 2010 -089 <br />Technical Revision No. 5 (TR -05) Adequacy Review <br />Dear Mr. Gilbreath: <br />The Colorado Division of Reclamation, Mining and Safety (Division) has completed its <br />adequacy review for Western Fuels- Colorado (WPC's) TR -05 application for the New Horizon <br />North Mine (NHN). TR -05 was submitted to address installation of ground water monitoring <br />wells GW -N56, GW -57, and GW -N58 and for proposed modifications to the mine facilities and <br />haul road construction and compaction. The Division submitted its preliminary adequacy review <br />letter dated December 5, 2013 regarding the new groundwater monitoring wells and the changes <br />proposed for Section 2.04.7 of the permit application package. This letter presents our <br />comments (Items 3, 4, and 5 below) regarding the proposed changes to Section 2.05.3(3) mine <br />facilities and haul road construction and compaction. <br />3. On proposed page 5 in Section 2.05.3(3), the final sentence which states, "The minimum <br />safety factor for all embankments will be 1.25." was removed. Please provide an <br />explanation for removing the minimum safety factor from your haul road construction <br />criteria on the proposed page 5. <br />4. In NHN's proposed changes to the haul road construction description, they removed their <br />requirement of compacting all embankment layers to 90 percent of Standard Proctor <br />density. The Rules do not require 90 percent Standard Proctor density for compaction of <br />embankments but the Division would like to understand the reasoning behind removing <br />this criterion for compaction. Please provide an explanation for removing the compaction <br />minimum criteria of 90 percent of Standard Proctor density for embankments. <br />5. The Facilities Map 2.05.3(3) -1 was changed significantly and resubmitted as a smaller <br />8.5 x 11 page. Maps should remain at their original full size for readability. Please <br />resubmit Map 2.05.3(3) -1 as a full size map. <br />Office of Office of <br />Mined Land Reclamation Denver • Grand Junction • Durango Active and Inactive Mines <br />