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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 />Denver, Colorado 80203 <br />Phone: (303) 866-3567 <br />FAX: (303) 832-8106 <br />14 August 2009 <br />Ms. Jennifer Sekulski-Barton <br />Colowyo Coal Company, LP <br />5731 State Highway 13 <br />Meeker, CO 81641 <br />Re: Colowyo Mine C-1981-019 <br />Second Adequacy Review - Technical Revision 78 <br />Dear Ms. Sekulski: <br />COLORADO <br />D IV IS I O N OF <br />RECLAMATION <br />MINING <br />SAFETY <br />Bill Ritter, Jr. <br />Governor <br />Harris D. Sherman <br />Executive Director <br />Ronald W. Cattany <br />Division Director <br />Natural Resource Trustee <br />The Division has received Colowyo Coal Company LP's (Colowyo) 24 June 2009 <br />responses to the Division's 4 February 2009 preliminary adequacy letter for Technical <br />Revision 78. The Division has reviewed the submittal and has the following comments <br />and questions. <br />General Comments <br />The measures proposed for approval under TR-78 are generally temporary. The revision <br />proposes three "internal ditches", A, B and C that divert runoff from mostly spoil areas <br />into the existing portion of the East Pit. The revision also proposes a temporary "sump", <br />constructed in the spoil area adjacent to the completed section of the Prospect post- <br />mining drainage, that captures the majority of flow (during the 10-year storm) from areas, <br />both disturbed and reclaimed, above the sump. And finally, the revision uses recently <br />approved hydrologic input parameters (from Technical Revision 73) to calculate flows <br />into Prospect Pond with the previously mentioned measures in-place. <br />1. <br />2. <br />3. <br />Colowyo has addressed this question. The curve numbers used were approved <br />with Technical Revision 73. <br />Colowyo has provided the requested SEDCAD runs. <br />Colowyo has addressed the soil group question. The soil group used was <br />approved with Technical Revision 76. <br />Office of Office of <br />Mined Land Reclamation Denver • Grand Junction • Durango Active and Inactive Mines