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• Section 1 <br />Introduction <br />This report presents the design analysis for the storm water drainage facilities at the <br />Sunday Mines Complex owned by Denison,Mines (USA) Corp. (Denison). The scope <br />of the report covers all aspects of storm water collection, conveyance, and detention <br />necessary to comply with U.S. Department of Interior, Bureau of Land Management <br />(BLM) and the Colorado Division of Reclamation Mining and Safety (DRMS) drainage <br />criteria. Detailed hydrologic and hydraulic calculations are provided in the <br />Appendices of the report. <br />1.1 Location <br />The Sunday Mines Complex is located in southwestern Colorado, on the south side of <br />Big Gypsum Valley, in San Miguel County, Colorado. The Sunday Mines Complex (or <br />Group) consists of five mine areas; Sunday, West Sunday, St. Jude, Carnation, and <br />Topaz. All five mine areas are on BLM resource claims for uranium and vanadium <br />extraction. Currently the Sunday, West Sunday, St. Jude, and Topaz Mines are active <br />mining operation sites but the Carnation Mine is on temporary standby status (URS <br />2007). The locations of the mines are shown in Figure 1. To investigate existing <br />conditions of the mine areas, CDM performed a site visit on May 13, 2008. <br />Photographs collected during the site visit are presented in Appendix C. <br />1.2 Procedure and Approach <br />A drainage report for Topaz Mine was developed by Tetra Tech EM Inc. in 2007 <br />(Tetra Tech 2007). CDM reviewed the Tetra Tech drainage report and provided <br />recommendations to improve the Topaz Mine drainage facilities designs. CDM also <br />addressed comments provided by the BLM on the Tetra Tech drainage report. For the <br />other mine areas (e.g., Sunday, West Sunday, St. Jude, and Carnation Mines), the <br />following procedure was used to design the drainage facilities components: <br />1. The peak discharge was estimated for a selected storm return interval using <br />drainage basin and climatic characteristics. <br />2. Drainage channels, berms, and catchment basins were designed to convey or <br />contain water for the selected return interval based on available AutoCAD data. <br />3. Channel bank and bed protection was designed for the estimated flow condition. <br />The document review and drainage facility design and recommendations for the <br />Topaz Mine are presented in Section 2 of this report. The designs of storm water <br />collection, conveyance, and detention facilities components for the West Sunday, St. <br />Jude, Carnation, and Sunday Mines are provided in Section 3 through 6, respectively. <br />+- • <br />1-1 <br />OWNS - DenisonWask Order I - Sunday Mines Droinape Study'ReporhFlnal Reporffinal Sunday Mines Drain.ps Rspon_O52208Ax