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-3- 7. If Middle Creek Mine detention pond 1s to be evaluated as a permanent pond, the following additions/clarifications need to be provided. a. The total sediment yield for this pond, Table A, seems high. See comment 4.c. above. b. The capacity of this pond is greater than 2.0 acre-feet and permanent water storage rights are required. c. Based on Map 3, Permanent Sediment Control Plan, the spillway is too close to its outlet into Middle Creek to have a slope of 0.03 ft./ft. Map 4, Hydrology, locates this pond much farther from Middle Creek. Please clarify. B. Diversion Ditches - Rules 2.05.4, 4.05.3 and 4.05.4 1. Ditch H3 splits into 2 ditches. Are both ditches constructed in accordance with the design provided for ditch H3? If this is not the case, the separate ditch designs need to be presented in the permit application. In addition, Map 4, Hydrology, shows only one ditch. 2. What erosion protection is being utilized to protect the pond side slopes at the point where the ditches enter the pond? 3. The design values for tributary area, CN, and runoff, as presented in Table 5, Culvert Schedule, for culvert 1 do not agree with the same values presented in Table 3, Diversion Ditch Schedule, for Ditch H2, which runs through culvert No. 1. 4. The shape correction used in the design of culvert No. 2 does not agree with the shape correction used for ditch P2, which runs through culvert 2. 5. Map 4, Hydrology, shows ditch P2 entering the Middle Creek detention basin at its western edge. Map 3, Permanent Sediment Control, shows the same ditch entering the pond close to its eastern end at the edge of the pond embankment. Please clarify. 6. Map 4, Hydrology, does not show the location of ditch P1. C. Haul Roads - Rules 2.05.3 and 4.03.1 1. The haul road cross-sections show the fill slopes as lh:ly slopes. According to Rule 4.03.1(3)(d), this slope is too steep unless tt can be demonstrated that this slope is stable. 2. In accordance with Rule 4.03.1(4)(a)(iii), the drainage ditches for the haul road and the associated sediment structures must be designed for a 70-year, 24-hour storm and the design presented in the permit application.