2023-10-31_REVISION - M1973021 (5)

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I Holcim-WCR,Inc. I Morrison Quarry Drainage Report Appendix F—Hydraulics It's assumed the channel will be riprapped lined and have a geotextile to reduce risk of infiltration. The design flow for 100-year and 5-year return periods are estimated in Appendix E and are 25.4 cfs and 6.6 cfs respectively. Table 1 — Design Flow Return Interval 5-year 6.6 100-year 25.4 Hydraulic Design Results The channel configuration along the bench is limited by the width of the inactive quarry bench. In concert with the geotechnical analysis the channel is proposed to have a bottom width of 2 feet, a constructed depth of 3 feet, side slopes of 2H:1V, and have a geotextile anchor trench along the reclaimed highwall with clay content material to mitigate potential infiltration of flows entering the channel. Details are presented in Appendix H — Design Drawings. The chute portion calculated by the NRCS workbook is identical to the bench except the bottom width is increased to 3 feet to ensure a commonly available D50 = 12 inch riprap material is stable. The results in the attached workbook and FlowMaster outputs are the basis of the design drawings presented in Appendix H. The superelevation of the flow in the chute portion is estimated using this USACE equation and a coefficient of 1.0 and design radius of 135 feet: ❑Y I.�Cl''T (8.8) Where; ❑Y _ Rise in water-surface elevation (superelevation) around the outside of a channel bend, in feet; C A coefficient (see Table 8.3); Y = Average velocity of flow, in feet per second; T — Channel width at elevation of water surface, in feet; g — Acceleration due to gravity (= 32.2 ft/sec2), rc = Radius of curvature of channel centerline, in feet; and, 1.5 — factor of safety to account For alluvial channel conditions. See U.S. Army Corps of Engineers (1970) for the source of this equation.