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III IIIIIIillllll III <br />999 <br />STATE OF COLORADO <br />DIVISION OF MINERALS AND GEOLOGY <br />Department of Natural Resources <br />1313 Sherman Sl, Room 215 <br />Denver, CO 80203 <br />Phone: 603) 866-3567 <br />FAX ~ 1303) 832-8106 <br />August 6, 1993 <br />Mr. Marcus Middleton <br />Twentymile Coal Company <br />29587 Routt Co. Rd. No. 27 <br />Oak Creek, CO 80467 <br />RE: TR-35 Adequacy Review, Eckman Park Mine, C-81-071 <br />Dear Mr. Middleton: <br />The Division has completed review of Technical Revision 35, permanent gully <br />maintenance work for PG 61-1, lower segment. Please respond assuming a <br />decision deadline of August 29, 1993. <br />OF' COQ <br />,sw~ <br />Ne ~~ <br />r8]6 ~ <br />Roy Romer <br />Governor <br />Michael g. Long <br />Division Director <br />Inspection of the SEDCAD+ hydrology routing network map shows two <br />branches meeting at junction 3. Junction 3 is also the entire watershed <br />outlet. Any time 2 or more branches meet at the final junction, another <br />junction is required immediately downstream to insure all hydrographs are <br />summed. Therefore, 4 junctions are required in this model. Please <br />correct your information, including Figure 32, and resubmit. <br />2. It is recommended that 2:1 sideslopes are used rather than 3:1 for the <br />riprap section due to the higher angle of repose for riprap and the <br />desire to minimize the disturbance. (i.e. smaller topwidth) <br />If you have any questions, please call me. <br />Sincer ly, <br />Kent A. Gorham <br />Reclamation Specialist <br />KAG/amm <br />8387E <br />