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The length of the side channel spillways was determined based on the following <br /> relationship: <br /> L5= 0.6 Ap/12,000 <br /> where: <br /> Ls = length of the side channel spillway <br /> Ap= areas of the pit measured in ft2 at the high water line. <br /> Table 6.4.7-1 — Side Channel Spillway Length and Elevation Calculations <br /> below gives this calculation for each of the Ponds. <br /> The elevations of the spillway channels (crest) set to 1 ft above the 2-year flood <br /> water surface elevation (WSEL). The 2-year WSEL's and the spillway elevations <br /> are also given in the table below. The 2-year flood WSEL's were determined by <br /> first running a HEC-SSP Bulletin 17C Flood Frequency analysis model with data <br /> from the Loveland Stream gage on the BTR. The model inputs and outputs are <br /> given in Appendix 6.4.7-A1 HEC SSP REPORT. The resulting value of 702 cfs <br /> was then entered into the HEC-RAS model developed for the No-Rise <br /> Certification Report (NRCR) prepared by Ayres &Associates (see Appendix <br /> 6.4.7-A2. The HEC-RAS model output for the 50 % chance flood event (2-year <br /> flood) is given below in Table 6.4.7-2. HEC-RAS Model Output 50% Chance <br /> Flood Event (2-year) <br /> Amen Aggregate Resource <br /> Specific Exhibits <br /> Page 36 of 84 <br />