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Page 4 of 6 <br /> <br /> In accordance with Rules 4.05.6(5) and 4.05.9(2) pertaining to supporting <br />calculations, documents, and drawings and spillway design requirements, <br />please revise Map 2.05.3(4)-6, page 2.05.3(4)-6, and the SEDCAD model to <br />indicate that the emergency spillway is a drop inlet structure. The barrel <br />length and slope should include the entire culvert length to its outlet on the other side of the county road, and the riser height should correspond to the <br />elevation of the spillway channel bottom relative to the county culvert <br />invert. On Map 2.05.3(4)-6, a spillway detail should be provided, and the <br />outlet end of the culvert should be shown. <br /> <br /> Riser height as depicted in blue <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br />6. DRMS: The SEDCAD run provided for pond NHN-001 is based on one 114.9 <br />acre watershed. The run also includes Muskingum routing information. The SEDCAD User’s Manual indicates that this routing function is used when there <br />are multiple subwatersheds and a given subwatershed does not flow directly to <br />the design structure but rather is routed (via ditch, culvert, etc.) to the structure. <br />This does not appear to be the case with the NHN-001 watershed. Please revise <br />the design to omit this routing or break the watershed into the subwatersheds indicated on Map 2.05.3(4)-1 and include appropriate routing for each <br />subwatershed and structure. <br /> <br /> WFC: The four SEDCAD runs included with this submittal were done with <br />Structure Networking Muskingum K & X values equal to zero, and used a single watershed, land flow condition 8 for the 114.9 acres watershed, as was done in <br />the approved permit SEDCAD runs. <br /> <br /> DRMS: Response accepted. <br /> 7. DRMS: The sedimentology portion of the SEDCAD run provided for pond NHN- <br />001 utilizes a control practice factor (C) of 0.45. The curve number used for the <br />watershed (91) indicates that the area is bare. Therefore, the “C” value should <br />be 0.9. Please revise the design accordingly.