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1 <br /> <br /> <br />1 <br /> <br /> <br />1 <br /> <br /> <br />applicant should submit calculations indicating that the proposed sediment storage <br />volume is sufficient for the sediment yield from the entire drainage area to the <br />pond. <br />RESPONSE: <br />The sediment storage volume has been re-calculated considering the sediment <br />yield from the entire tributary area for the 10-yr., 24-hr. design event. The <br />pond will be sized to provide for this volume at all times. The calculations are <br />included in revised Exhibit la, Sedimentation Pond and Diversion Ditch <br />Designs under Sediment Volume on page 3 and 4. <br />4. The applicant should indicate the cleanout frequency anticipated to <br />maintain sufficient open sediment storage in the pond. Available sediment storage <br />in the pond should be sufficient to contain either one year's sediment yield or the <br />sediment yield from the 10-yr., 24-hr. rainfall event. <br />RESPONSE: <br />' As explained under comment !f3 above, the sediment storage capacity is <br />designed to contain the sediment generated by the 10-yr., 24-hr. event at al! <br />times. The pond will be cleaned out when it is 60% full of sediment. <br />Documentation of sediment storage and cleanout is shown in the revised <br />Exhibit la, Sedimenation Pond and Diversion Ditch Designs, on page 4. <br /> <br />1 <br /> <br /> <br /> <br /> <br /> <br /> <br />5. The applicant failed to adjust the peak flow estimate of the 25-yr., 24- <br />hr. rainfall event for varying basin shape. Peak flow should be reestimated making <br />both the slope and basin shape adjustments. (Refer to Appendix E in Peak Flows in <br />Colorado.) <br />RESPONSE: <br />The basin shape factor was calculated to be 0.96. Therefore, when the peak <br />flow was calculated in the original submittal, this factor was not included <br />inorder to yield a more conservative peak flow for the design of the <br />emergency spillway. Considering the importance of the emergency spillway, <br />CYCC prefers to use the more conservative peak flow rate used in the original <br />application submittal and included in revised Exhibit la, Sedimentation Pond <br />and Diversion Ditch Designs. <br />2 <br />