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2000-11-20 WC Dept of Hwys Bridge Replacement Recommendation DEC-07-2005 (WED) 13:11 P.0021002 .. () , November 20, 20()() ee~'\J~d 1YOM 11- /I""' ()~ ......, ~ ) $'eH W Olyne Fingalson. P .E. Wright County Highway Depo.rtment 1901 Hwy 2S N Buffalo, MN 55313, MN RE: Replacement recommendation for Bridge 8430 on CSAH 18 Sec. 2, T.12O-N, R.24-W. Dear Mr. Fingalson: Enciosed are copies of calculation sheets and a risk assessment for sizing cu1ve~1S to replace the abov;: referenced structure. The recommended size and pertinent hydraulic data are as follows: Recommended Culverts ................................. 1 - 12 ft x 8 ft Box Culvert ... S~....................... . . . . . . . . . . . . . . Co. Ditch #9 ... Drainage Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.23 sq. mi. . Flood of Record ....................................... Unlmown Maximum Observed Highwatcr . . . . . . . . . . . . . . . . . . . . . . . . . ..: Unknown ... Design and Basic Flood (1 00 Year Frequency) ............... : .' 29~..~fs III Headwater Elevation ............................... : i.....~51.5..-:~, Stage In.crease .......,...........,.... a .. .. . .. .. .. . . . . . . . ..: o"'i' ft. . Stage Increase for Existing Structure. . . . . . . . . . . . . . . . . ..: 0.25 ft. Approximate Roadway Sag Point Elevation. . . . . . . . . . . ..: 957.7 Mean Velocity Through Structure. . . . .. . . . . . ... . . . . . ..: 2,5 fps Mean Velocity in Channel. . . . . . . . . . . . . . . . . . . . . . . . . ..: 1.75 tps Greatest Flood (500 Year Frequency) ......................: 350 cfs ... Headwater Elevation ............................... 953.0 Stage Increase .........................................: 0.3 ft Mean VelocityTbrough Structure.... .. . . . .. .. . .. .. . ..: 3.7 ips Approximate Inlet Invert Elevation ........................: 944.5...... Approximate Outlet Invert Elevation. . . . . . . . . . . . . . . . . . . . . ..: 944.3*. '" This infonnatio~ should be shown on the plan sheet(s) ** These arc suggested invert elev~tio!ls) !f a designated ditch flowline is available, the culvert should be set at that elevation. The above design. data is based on field survey data. provided by Wright County for this pt'Oject. I hereby certify that this report was prepared by me or under my direct supervision, and that I am a duly registered professional engineer under the laws of the State- of Minnesota. L?~gJ~ Brian D. Walter, P.E.. Reg. No. 13896 Date: // ho/t:;o EXHIBIT ... .!! ~ F :I