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-~ - <br />TRAPPER 1CIpIp6 IpC. <br />~II II~~I~~I~~I~~ ~I~ <br />March 28, 1995 <br />CERTIFIED 2067066355 <br />Mr. Jce Dudash <br />Colorado Division of Minerals & Geology <br />1313 Sherman Street, Room 215 <br />Denver, CO 80203 <br />Dear Mr. Dudash: <br />s~ECEIVEf~ <br />APR ~ 3 1995 <br />Division or imineraw a uduiogy <br />Re: Trapper Mine (Permit No C-81-010) Revision TR-67 (Oak Ponds) <br />Enclosed are pond/embankment designs and the hydrology and sedimentology calculations for Oak ponds <br />No 1 and No 2 to be constructed at Trapper Mine this summer. To process this revision, various changes <br />are needed to our Mining and Reclamation Permit. Initially, a new Appendix Q Section XXVI (Oak <br />Hydrologic Model) is provided. Also included are revised permit maps M51, sheets 3 of 4 and 4 of 4, and <br />updated Permit tables 4.8-6 (page 3)and Table 4.8-7. <br />Finally, design calculations for the outflow of Oak Pond No. 2 aze provided which are to be included in <br />Appendix Q, Section XIX. Previously, Trapper had committed to rip-rapping all future pond outflows <br />where velocities are projected to exceed 5 feet per second. Discussions with Division personnel indicated <br />that rip-rapping only the final pond outflow ta a drainage is sufficient since possible erosion with an <br />upstream outflow will be controlled within the final pond. <br />The design included within Section Xllt is based on the use of rip-rap. The rip-rap will be a durable stone <br />secured from the mine site and will meet the design size as closely as practicable. Trapper is also currently <br />investigating the use of synthetic erosion wntrol fabrics. Should Trapper elect to use this approach, a final <br />design will be forwarded to the Division for approval. <br />Outflows for ponds other than the final will be constmcted with techniques more typical of those curcently <br />in use at Trapper. These techniques, which include excelsior blankets, vegetation and some rip-rap, have <br />proven generally adequate with only minor erosional problems. As stated earlier, any minor problems will <br />be controlled within the downstream pond. <br />Should you have any questions or require further information, please wntact Mazk Wehmanen or me. <br />Sincerely, f'^Z <br />orcest V. Luke <br />Environmental Manager <br />LWIVMW W/jsb <br />(95-MAR78J <br />me <br />c MW Wehmanen, Trapper <br />1M Matlern, Trapper <br />P.0. Box 187 <br />Craig, Colorado 81626 <br />(303) 824-4401 <br />