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NINE "I'lls 1111 1 1111 <br />1w%] TET'RATECH <br />hibit was prepared to reevaluate the mine water control plan at West Elk Mine, <br />This ex <br />documented in the September 1993 Mine Water Control Plan, and subsequently revised several <br />times from 1996 through 1999. This revision presents an updated SEDCAD analysis of the <br />mine's surface water collection and treatment system, based on field inspections of the existing <br />ditches and culverts. The analysis also reflects proposed repairs, to be constructed from Fall <br />2008 through Summer 2009. The analysis was based on previous analyses provided by West Elk <br />Mine, and field confirmation of site conditions. Survey information from previous design was <br />accepted, but not checked. <br />The analysis includes the watersheds and drainage networks reporting to Ponds MB-1, MB-2R, <br />MB-3, MB-5, NSSA, RPE, and SG-1; cleanwater diversion outfalls; and outfalls to natural <br />drainages within Sylvester Gulch. Updated site maps and drainage network diagrams are <br />included. No changes have been made to existing previously approved Small Area Exemption <br />demonstrations, or to Pond MB-4. <br />With consideration to applicable drainage principles and generally accepted engineering <br />standards and procedures, the analysis submitted provides for the drainage and storm water flow <br />from the subject site areas to be in accordance with applicable requirements, and to the best of <br />my knowledge, represents good standard engineering practice. The drawings presented herein <br />are for permitting purposes. <br />RED/ <br />33892 <br />!oNAL <br />Troy Meyer, PE <br />Tetra Tech <br />715 Horizon Drive, Suite 300 Grand Junction, CO 81506 <br />Tel 970.986.3566 Fax 970.241.3120 www.tetratech.com