2011-04-05_REVISION - C1982057 (2)

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22. On Section C-C', the existing Pond 016A impounding structure is centered at -Sta. 1+90. As shown, the Proposed Surface will result in fill above the elevation of the current structure and on the downslope of the structure. This configuration appears to contradict the text description provided in the Pond 16 Area Stabilization Plan Summary (Page 3 of the application), which states, under Pond 016A Removal, "a portion of the existing embankment will be lowered/removed to drain the current pond and then be reconfigured to fit the relocated Channel PM-2 design." Please clarify the text and/or map and cross section to provide consistency within the application. 23. On Section D-D', please depict the location of Road J/K, as the Division also requests for Sections B-B' and C-C', above. 24. Comparison of Section D-D' with the plan view on Sheet 1 indicates that Channel PM-2 will cross this section at -Sta. 1+85. Please modify this section to accurately depict the proposed location and configuration of channel PM-2. 25. The existing Pond 016 design and as-built report indicate that the riser height of the drop- inlet spillway is 5', with a spillway invert elevation of 7,462.00'. The new design retains the spillway invert height of 7,462.00', but indicates the riser height will be 2.5'. Is SCC proposing to modify the drop inlet spillway? 26. The design submitted for Pond 016 includes the two stock tanks (T-26 and T-27) as sediment control features. The previously approved language in the permit application package, on page 11 of Tab 13, indicates that the stock tanks are not primary sediment control structures. If SCC intends to rely on these structures to control runoff and sedimentation, the language of Tab 13 will need to be revised accordingly. Also, SCC will need to submit detailed design information, as required by Rule 4.05.6(5), indicating that Stock Tanks T-26 and T-27 will comply with Rules 4.05.6 and 4.05.9. 27. If the stock tanks are an integral part of the runoff and sediment control system as indicated in the proposed Pond 016 drainage area plan, they would need to be maintained at their design capacity until SCC can make a demonstration, under Rule 4.05.2(2), that the quality of untreated drainage from the disturbed area meets applicable water quality standards. Both stock tanks are a considerable distance from LU-6 (T-27 is about 1,500' away-and T-26 is about 500' away). SCC will need to address access to the stock tanks for maintenance during the period of time that the stock tanks are necessary for sediment control. 28. The SEDCAD run for Pond 016 uses a curve number of 71 for reclaimed areas, based on "good (>70%)" vegetative cover and a C type soil group. This value appears to be based on approved input values found in the permit application package, in Appendix 13-513; the tables in Appendix 13-513 are derived from NRCS TR-55. The vegetation monitoring reports