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M I _10 ~ Di'1 S~\~ill US ~~` ~ d. The total sediment yield for this pond seems high (Table A). The Dh1f J~ applicant states on page 2.05-94 that it is estimated pre-mine 1 ~' ~~ productivity should be reinstated on all revegetated areas in /%~ h~ f substantially less than the three year's time proven in 1974 ~l''~ ~~~a~ ~~'~~ reclamation. The calculations presented use a reclamation period of 10 ( (/C years. Also, 1t is estimated that sediment transport will be further ~C~~~ reduced using contour furrows. II I ~~i, ul~l II ~ I e. If re-evaluation of the sediment yield increases the capacity of IG~~f~~ the pond to above 2.0 acre-feet, then permanent water storage rights are C~ required. ~~// /~ ~ ~ ~7y~ f. The spillway, as shown on the Permanent Sediment Control Plan, Map 20, is nat drawn to scale. This should be corrected. w .~f c ~~~~ 1. If Middle Creek Mine Detention Pond is to be evaluated as a permanent pond, the following additions/c lartfications need to be provided. a. The total sediment yield for this pond seems high (Table A). See comment 6.e. 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 1s too close to its outlet into Middle Creek to. have a slope of O.D3 ft./ft. Map 4, Hydrology, locates this pond much farther from Middle Creek. Please clarify. C. Diversion Ditches 1. Ditch H3 splits into 2 ditches. Are both ditches constructed in accordance with the design provided for ditch H3? If this 15 not the case, the separate ditch designs need to be presented 1n the permit application. In addition, Map 4, Hydrology, shows only one ditch. ~/~ ~~v~0lQivr4 ~,..~ // cny/~;JC 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 No. 1 do not agree with the same values presented in Table 3, Diversion Ditch Schedule, for Ditch H2, which runs through Culvert No. 1. This discrepancy needs to be addressed. 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. This needs to be corrected. ~~rr~ L~ / ,~ V"~ D G~ 5. Map 4, Hydrology, shows Ditch P2 entering the Middle Creek Detention Basin at its western edge. Map 3, Permanent Sediment Control Plan, shows the same ditch entering the pond close to its east end at the edge of the pond embankment. Please clarify.