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• Construct a longitudinal profile that remains stable, and to the • <br />extent possible control erosion using channel lining structures in <br />accordance with Rule 4.05.4 (2)(a). <br />• Provide adequate capacity to safely convey the peak discharge from <br />the 100-year, 24-hour storm event in accordance with Rule <br />9.05.4(21(6)• <br />Channel SIIPM-1 is sub-divided into three reaches see Exhibit 13-23). The <br />upper reach (identified as Channel 1 Upper in the SEDCAD modeling in <br />Appendix 7-12A) stretches from Culvert 19-A (stationing 50+21.93) to <br />stationing 34+50. The contributing drainage area to Channel 1 Upper is <br />approximately 868 acres. The 2004 SE DCAD4 modeling indicates the peak <br />discharge for the 100-year, 29-hour storm event from this catchment area is <br />52.2 cubic feet per second (cfs). However, the channel was designed to <br />safely convey a peak discharge of 119 cfs (see the Channel Design Summary <br />table in Appendix 7-12B). <br />The middle reach, identified as Channel 1 Middle in the SEDCAD+ modeling in <br />Appendix 7-12A, stretches from stationing 34+50 to Culvert 15-A <br />(approximately stationing 8+80). The contributing drainage area to Channel <br />1 Middle is approximately 1,459 acres. The 2009 SE DCAD4 modeling indicates <br />the peak discharge for the 100-year, 24-hour storm event from this <br />catchment area is 70.1 cfs. This channel reach was also designed to safely <br />convey a peak discharge o£ 119 cfs (see Appendix 7-12B). <br />The lower reach, identified as Channel 1 Lower in the SEDCAD+ modeling in <br />Appendix 7-12A, stretches from Culvert 15-A (stationing 8+80) to Pond 002 <br />(stationing 0+00). The contributing drainage area to Channel 1 Lower is <br />approximately 2,702 acres. The 2004 SEDCAD9 modeling indicates the peak <br />discharge for the 100-year, 24-hour storm event from this catchment area is <br />134 cfs. Consequently, the lower channel section was designed to safely <br />convey a peak discharge of this magnitude (see Appendix 7-12B). <br />As-Built Construction <br />SCC completed an as-built survey of Diversion Channel SIIPM-1 during August <br />and September 2005. Exhibit 7-23, Channel SIIPM-1 Profile and Sections, is <br />a certified as-built drawing that presents the plan view, longitudinal <br />profile and typical cross-sections of this permanent diversion channel. . <br />TR-37 2 Aevised 10/OS <br />