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• APPENDIX M -HYDROLOGIC CALCULATIONS <br />EAST SALT CREEK BRIDGE: <br />The road to the McClave Canyon Mine crosses East Salt Creek Regulation 4.03. I (4) <br />requires that the bridge be designed to safely pass the flows from a 20 year, 24 hour <br />precipitation event <br />Flow Calculations <br />Use 10 ft by 16 ft opening. <br />Area = 160 ft~ <br />Slope -from X-C's 5.6' / 295' = 0.019 ft/ft <br />Manning Number <br />• For Earth Bottom and Rubble sides n = 0.032 <br />For Earth Bottom and Wood Crib sides use n = 0.04 <br />Flow -from Manning Equation <br />Q= 1.49/nX Rv3 S~'A <br />Q = 1.49 / 0.04 X (I 60/36) "' (0.019)'n 160 <br />Q = 2,200 CFS <br />From Hydrotriad Report ,November 1980 (see Munger Canyon Permit , Apx Mv) <br />Qioo = 1,929 cfs <br />Rule 4.03. I (4)(e) requires that this bridge be designed for the 20 year 24 hour event; therefore, <br />the bridge has adequate capacity. <br />C~ <br />Mc Vol III Page I 10 - 13 - 97 <br />