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<br />TRAPPER MINE RESPONSE TO PR-1 ADEQUACY RESPONSE DOCUMENT <br />May, 1987 <br />4. Surface Water and Sediment Control <br />6. Sizing of the diversion ditch to lead to Coyote Dam. <br />Trapper should also discuss how the diversion ditch will be designed to <br />minimize erosion, such as low gradients. <br />Response <br />Enclosed is the requested information for proposed Coyote Diversion No. <br />1. <br />The peak flow rate for Coyote Diversion Ditch No. 1, routing runoff from <br />the disturbed area, was determinedd by the use of hydrologic modeling <br />techniques. A runoff model was created for the watershed under the <br />10-year, 24-hour precipitation event. The results of the hydrologic <br />model are presented in Appendix Q, Section 3, Drainage and Sediment Con- <br />trol Plan (attached). <br />A11 major diversions are built with side slopes of 3H:1V and a slope of <br />no greater than two percent (Table 1). All diversions will have a mini- <br />mum freeboard of 0.3 feet. <br />The location of Coyote Diversion Ditch No. 1 will be within 100 feet of <br />plan (see Map M51, Drainage and Sediment Control Plan). However, unless <br />Division approval is received, the Location of the proposed point of dis- <br />charge won't be changed if it results in a functional change to the over- <br />all system design. Modifications exceeding 100 feet laterally or other <br />such major modification to Coyote Diversion No. 1 will be submitted to <br />the Division for approval. <br />Coyote Diversion Ditch No. 1 will be inspected annually following spring <br />runoff and upgraded or maintained as needed. <br />