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12-18-85 <br />Stipulation No. 13 Response <br />• As shown in the Drainage and Sediment Control Plan Appendix, Appendix 1, <br />the channel for Ditch No. 3 or the West Ditch, has been designed as a <br />"V" ditch 1.53 feet deep with 7.5H:1V side slopes. The depth of flow is <br />calculated at 0.53 foot for 2.6 cfs. The peak flaw of 2.6 cfs is the <br />estimated flow from a 100-year, 24-hour precipitation event. Therefore, <br />the ditch channel, as designed, is adequate to pass the peak flow from a <br />10-year, 24-hour event. <br />Stipulation No. 14 <br />The applicant must install a staff gage clearly marked with the 60% <br />cleanout elevation in the sediment pond. <br />Stipulation No. 14 Response <br />Peerless Resources, Inc. has installed a staff gage in the sediment <br />pond. <br />Stipulation No. 15 <br />• Before the permanent pond design can be considered adequate, the <br />applicant must justify the use of a curve number of 72. This must be <br />done within thirty (30) days of permit issuance. <br />Stipulation No. 15 Response <br />Curve No. 72 has been selected based on the soils and estimated <br />vegetation type and cover for the area which has not been disturbed by <br />mining within the drainage basin for the sediment pond. Due to the <br />temporary nature of the sediment pond, the area has been divided into <br />the disturbed area and undisturbed area for calculation purposes. <br />Curve Na. 72 is based on use of Hydrologic Soil Group D and~a vegetation <br />type of sage-grass with ground cover density of 50 percent. The soil <br />group D represents a conservative estimate given the soil types in the <br />drainage basin. The vegetation type of sage-grass was selected because <br />the undisturbed portion of the drainage basin most closely resembles the <br />sage-grass vegetation type. The estimated ground cover density was <br />• estimated to be approximately 50 percent based on field inspection. <br />-6- <br />