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2-18 <br />The channel relocation shall safely pass the surface runoff <br />• from a 100-year, 24-hour precipitation event. For channel <br />crossings as indicated in Figure 2.3-2.25, two 60" diameter <br />culverts, side by side, shall safely pass 400 cfs with a <br />maximum anticipated head of 7.5 feet (1.5 x diameter of cul- <br />vert). For hydrologic and hydraulic data, see Appendix As. <br />The construction of Munger Creek relocation will require <br />the excavation of approximately 90,210 yd.3 of material. <br />All salvageable topsoil will be removed and stockpiled (ap- <br />proximately 3,005 bank cubic yards) as described in Section <br />2. 5. The remainder of the excavated material (37,205 bank <br />cubic yards) shall then be used for embankment in the central <br />facilities area. Any excess material unsuitable for embank- <br />ment shall be disposed of or stockpiled in the designated <br />areas. A minimum depth of six feet will be maintained through- <br />out the entire channel relocation. A minimum depth of ten <br />feet shall be maintained at the entrance to the culverts to <br />• provide 2.5 feet of freeboard. <br />To insure stabilization of the new channel geometry, conven- <br />tional erosion control measures shall be employed. Stabiliza- <br />tion shall be provided by the placement of dumped rock on the <br />channel bottom and revegetation of the channel slopes. Where <br />excavation of diversion channel is through rock, erosion <br />control measures shall not be required. <br />`I <br />