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f <br />_ • <br />2 WEST PORTALS <br />CULVERT DESIGN <br />Kiddle Area Undisturbed Drainage, 100-year event <br />? West Portal Area, Powderhorn Coal Company <br />HASIN CHARACTERISTICS <br />DRAINAGE AREA (SQ. MI.) = 0.065 <br />STREAM LENGTH (MI.) = 0.424 <br />ELEVATION DIFFERENCE (FT.)~ = 1110.000 <br />RUNOFF CURVE NUMBER, CN = 78.000 <br />MINIMUM INFILTRATION IASS (IN./HR.) = 0.150 <br />PRECIPITATION FOR SPECIFIED STORM <br />~„ • ADJUSTED PRECIPITATION FOR SELECTED STORM (IN.) = 2.20 <br />UNIT HYDROGRAPH PARAMETERS <br />UNADJUSTED TIME OF CONCENTRATION {HR.) = 0.06 <br />ADJUSTED TIME OF CONCENTRATION (HR.) = 0.07 <br />DURATION OF EXCESS RAINFALL, D (HR.) - 0.01 <br />TIME TO PEAK (HR. ) = 0.05 <br />BASE TIME {HR. ) 0.12 <br />QPEAK (PEAK FLOW IN CFS FOR UNIT HYDROGRAPH) = 674.1 <br />RESULTANT HYDROGRAPH VALUES <br />PEAK DISCHARGE (CFS) = 36.79 <br />RUNOFF VOLUME (ACRE-FEET) = 1.01 <br />TIME TO PEAK DISCHARGE (HR} = 12.01 <br />USED SCS TYPE II 24-HOUR GENERAL STORM <br />Culvert Design <br />Reference: Figure 4-18, Inlet Control Monogram for CMP, Page 161, <br />. Handbook of Steel Drainage & Highway Construction Products, <br />American Iron and Steel Institute, 1971 <br />_. ~ A 24" CMP with end section conforming to fill slope and a 1.50 headwater <br />depth to diameter ratio will carry 20 CFS. Use 2 24" CMP <br />~415C - 3 (New 8-28-92) <br />