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Page 3 of 6 <br /> <br />stated on page 6, “gated principle spillways, as designed for all three ponds, <br />prevent short circuiting.” <br /> <br /> DRMS: Response accepted. <br /> 5. DRMS: Please include design information for the emergency spillway channel to indicate the flow depth and demonstrate adequate embankment height to ensure <br />1’ of freeboard, as required by Rule 4.05.9(7)(d). <br /> <br /> WFC: The four SEDCAD runs for the as-built pond show no discharge through the emergency spillway, therefore no emergency spillway flow is indicated for <br />use in calculating freeboard. The minimum freeboard resulting from there four <br />SEDCAD runs occurs during the 25yr-24hr seep holes closed case, where the <br />peak pool stage elevation is 5,676.62 ft. This provides for 2.88 feet of freeboard <br />to the top of the dam at 5,679.5 ft. The emergency spillway has been built to the elevation of 5,677.5, two feet lower than the top of the dam embankment. The <br />approved Pond NHN-001 design done by Arcadis included a 25yr-24hr SEDCAD <br />run assuming no flow through the primary spillway, resulting in a flow depth <br />through the designed 10 ft. wide, 2:1 side slope emergency spillway of 0.18 ft. <br />The resulting freeboard in such a scenario is 1.82 ft. In this worst case situation, where the primary spillway would become blocked, the emergency spillway as <br />built would still have greater than the required 1.0 of freeboard. The emergency <br />spillway channel as-built is a rip-rapped trapezoidal channel, 10 ft. wide with <br />2h:1v or flatter side slopes. <br /> <br /> DRMS: The response adequately addressed our concern with demonstrating adequate freeboard in the emergency spillway channel. The <br />design information provided, however, does not accurately reflect the as- <br />built configuration. Map 2.05.3(4)-6, the text on page 2.05.3(4)-6, and the <br />SEDCAD reports all indicate that the emergency spillway is an open channel flowing southward over the embankment. Photographs of the constructed spillway, taken on December 12, 2012, indicate that the <br />emergency spillway has been blocked on the south side, forcing flow <br />through a drop structure to the county road culvert. <br /> Embankment is built up on <br />south end, forcing flow into drop structure <br /> <br /> <br /> <br />