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Michael Boulay May 21. 2008 <br />17. DRMS: The CDPHE Discharge Permit contained in Appendix E needs to <br />be updated with the new sediment pond. <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 <br />it becomes available. <br />CAM: Discharge permit has been applied for and will be supplied to DRMS <br />when granted. <br />18. DRMS: In the spreadsheet calculations pages for the proposed sediment <br />pond, there are references to the "office pond" and the "new pond". <br />Please amend the references to use consistent nomenclature. <br />CAM: The pond nomenclature was changed to 'office pond'. Please see revised <br />PHC pages. <br />19. DRMS: From the information submitted with TR-16 it is unclear how the <br />pond will be operated. The 25yr-24hr SEDCAD run shows that the entire runoff <br />volume will be contained by the new sediment pond. There are runoff volumes <br />and sediment volumes provided in Appendix N along with a pond capacity table <br />shown on Figure 2.2-3. However there is no stage storage curve or elevation- <br />capacity-discharge table provided to clearly show the peak stage from the 25yr- <br />24hr event. Further, the top of the sediment storage level is unclear because <br />Section A-A' on Figure 2.2-3 shows the sediment storage elevation at 5415.5 ft., <br />which is above 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 />CAM: The Impoundment was/is designed according to rule 4.05.9(2)(b) <br />providing for a primary and an emergency spillway. The pond was designed to <br />contain the 10-yr 24-hr event, and the emergency spillway was sized to safely <br />pass the 25-yr 24-hr event. The pond design is in Appendix M, on pages 24-26. <br />The maximum sediment storage, as well as water storage is shown on Figure <br />2.2-3, Section A-A'. As shown on page 2-48, sediment will be cleaned as