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<br />~ <br /> <br />';' <br /> <br />the br i dge is to be rep! aced for reasons other than to meet requ i re- <br />ments for flood protect ion, the new structure has not been inc luded <br />as a project feature. <br /> <br />9. The water surface profi Ie for the design discharge, as shown <br />on plates 2 and 3, was determ i ned by Lackwater computat ions us i n9 "n" <br />values of 0.020 for channel flows and 0.035 to 0.070 for overbank flows. <br />Channel velocities at design discharge range from I I to 21 feet per <br />second. Velocities in the overbank vary from 2 to 9 feet per second. <br /> <br />" ..' <br /> <br /> <br />8. Overbank clearing under the new highway bridge and the exist- <br />ing rai Iroad bridge would give a flow width of 800 feet at the highway <br />br i dge and 858 feet at the ra i I road br i dge. Overbank clear Inga I so <br />would be maintained between the bridges so that the cleared width plus <br />the channel would equal the flow width of the bridges. The clearing <br />would be extended a short distance above the highway bridge and below <br />the rai Iroad bridge to maintain an "n" value of 0.035 in the vicinity <br />of the br i dges. <br /> <br />10. RAILROAD GRADE RAISE.- In the vicinity of levee station 4+00 <br />the levee al ignment would cross the main line of the AT&SF where an <br />opening would be provided. The rai Iroad would be raised 6.0 feet at <br />th is po i nt wh i ch wou I d pi ace it at the des i gn water surface. Sand- <br />. bagg i ng wou Id be requ i red to prov i de freeboard. The ra i se woo I d requ ire <br />ramping of about 4,900 feet of single track and alteration of smal.1 <br />bridge structures in this reach. The maximum grade for the raise would <br />be 0.36 percent which is equivalent to existing rai I road grades in the <br />area. It would be necessary to lay a shoofly for routing traftic <br />dur i ng construct i on of the grade. ra i se. <br /> <br />II. RAILROAD BRIDGE ALTERATION.- In order to provide adequate <br />waterway open i ng for the des i gn f low and ma i nta i n ex i st ing ra i I road <br />grades, it would be necessary to alter the rai Iroad bridge on the <br />Arkansas Valley Branch I ine across the Arkansas River. It is proposed <br />to reconstruct the 416-foot deck plate girder bridge and replace por- <br />t ions of the ba II ast deck pile trest Ie to form a 550-foot thro!Jgh plate <br />girder br i dge des I gned to carry E -65 load i ng. The ba II ast deck pile <br />trestle on the north end of the bridge and approximately 80 feet of <br />the bal last deck pi Ie trestle on the south end would be replaced. <br />This work would require one new abutment on the north end of the bridge <br />and one new pier on the south end of the through plate girder section. <br />Also, the five existing piers would have to be raised approximately <br />6 feet. This alteration would increase the horizontal clear waterway. <br />opening by 135 feet and the vertical clearance by 6 feet. Detai Is of <br />the proposed alterations are shown on plate 4. <br /> <br />12. COUNTY ROAD RELOCATION.- The levee al ignment crosses a 2- <br />lane gravel-surfaced county road in the vicinity of levee station <br />82+00 and again in the vicinity of station 109+00. It is proposed to <br />relocate 2,700 feet of this county road adjacent to the lands ide toe <br />of the levee. <br /> <br />A-3 <br /> <br />R 1/28/64 <br />