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Section 5 <br />Camation Mine <br />elevation. CDM also recommends connecting any breached areas along the berm. <br />Details for this calculation are included in Appendix B. <br />The total runoff volume of Basin 3 was calculated to evaluate the required depth of <br />the sediment pond. The existing pond has an area of 5,724 square feet. Based on this <br />area, the minimum required depth of the pond is 2.5 feet. Therefore, including 1-foot <br />freeboard, a depth of 3.5 feet is required for the pond to contain the 100-year, 24-hour <br />storm event. Details for these calculations are included in Appendix B. <br />The total runoff and sediment volume of Basin 4 will be contained within existing <br />water bars and vegetation due to the mild basin slope. <br />5.5 Conclusions and Recommendations <br />CDM proposed additional control structures to route offsite surface flow around the <br />surface mine area and contain the 100-year, 24-hr storm event within the onsite berms <br />and catchment. CDM recommends the following for Carnation Mine storm water <br />drainage control: <br />1. A grass-lined channel with a depth of 3.0 feet for the proposed Channel 1. <br />2. Increasing the height of the existing Basin 2 berm, where it is less than 1.5-feet <br />high, to 1.5 feet and connecting any breached areas along the berm. <br />3. Maintaining the existing Basin 3 sediment pond area and increasing the depth to <br />3.5 feet to contain the 100-year, 24-hour storm event. <br />A plan view of the catch basin and channels is included as Exhibit D-1 and details are <br />included in Exhibit D-2. <br />• <br />?-' <br />5-4 <br />OIA4986 - Denisoffask Order 7 - Sunday Mims Drainage SWdyWeponWinal ReportlFinel Sunday Mines Drainage Report 052208.doc