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' y. <br />Please provide a copy of the application for revision (submitted to WQCD) <br />and provide a copy of the amended discharge permit to the Division when it <br />becomes available. <br />18. In the spreadsheet calculations pages for the proposed sediment pond, there are <br />references to the "office pond" and the "new pond". <br />Please amend the references to use consistent nomenclature. <br />19. From the information submitted with TR-16 it is unclear how the pond will be <br />operated. The 25yr-24hr SEDCAD run shows that the entire runoff volume will <br />be contained by the new sediment pond. There are runoff volumes and sediment <br />volumes provided in Appendix N along with a pond capacity table shown on <br />Figure 2.2-3. However there is no stage storage curve or elevation-capacity- <br />discharge table provided to clearly show the peak stage from the 25yr-24hr event. <br />Further, the top of the sediment storage level is unclear because Section A-A' on <br />Figure 2.2-3 shows the sediment storage elevation at 5415.5 ft., which is above <br />the elevation of the primary spillway (5415.3 ft.). <br />Please provide revised design information in both text and Figure 2.2-3 <br />which clearly explains how the new sediment pond will be operated (e.g. <br />manual versus passive discharge, with detailed design specifications). The <br />revised information shall also provide a demonstration of compliance with <br />Rules 4.05.6(3) (b) and 4.05.2(7). This demonstration should identify the <br />maximum sediment storage volume, cleanout level, and the estimated <br />periodic sediment removal interval. Compliance with these permit <br />commitments shall be demonstrated and documentation of the existing <br />storage capacity shall be provided annually in the Annual Certification for <br />Impoundments required by Rules 4.05.9(14) and (15). <br />20. Statements on revised page 2-27i, indicate that the impoundment is located where <br />serious property damage may occur. Therefore, in accordance with <br />4.05.9(2)(e)(ii), the pond should be designed to control the 100-year 24-hour <br />event. <br />Please provide revised design information which clearly demonstrates <br />compliance with 4.05.9(2)(e). If the pond is a temporary impoundment it <br />may rely primarily on storage to control the runoff from the design event <br />specified in 4.05.9(2) (c). The demonstration should show how the water will <br />be safely removed in accordance with current, prudent, engineering <br />practices. <br />21. The primary spillway pipe on the proposed sediment pond extends to the channel <br />of lower McClane Creek. <br />7