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<br />0018i5 <br /> <br />J. Tieback Levee, North Side <br /> <br />To not permit flood flows to outflank the levee system, the levee <br />should be tied back to higher ground from the upstream end of the <br />existing levee. The northerly levee would consist of about 7100 <br />feet of levee from about river station 275+00 (Sheet 1) to North <br />River Road at the Maddux Ditch, then northerly to the intersection <br />with 4-1/2 Mile Road in Sec. 28. The proposed elevation of the <br />tieback levee, to protect the area for the 100-year flood <br />including 3-feet of freeboard, is 7548. Riprap erosion control is <br />recommended at the corner of the tieback levee and the river levee <br />system. Figure 9 shows a typical section of the tieback levee. <br />Figure 10 shows the approximate location of the north side tieback <br />levee. <br /> <br />Two a lternat i ves ha ve been cons i dered for a tieback 1 evee on the <br />southerly side of the river. Alternative 'A' excludes the <br />Riverwood Estates subdivision from flood protection and Alternate <br />'B' provides flood protection to the new subdivision. <br /> <br />, <br /> <br />I <br /> <br />K. Tieback Levee, South Side <br /> <br />1. Alternate 'A' <br /> <br />Alternate 'A' tieback 1 evee does not i ncl ude the R i verwood <br />Estates (Anderson) subdivision recently platted at the <br />northwest end of Alamosa. This alternative proposes a new <br />1 evee that traverses through unimproved areas of the Carroll <br />Addition and a portion of Harold Carrol Park, as shown in <br />Sheet 1. This alternative is the less costly of the two <br />considered. The Riverwood Estates subdivision would remain in <br />the floodway, as it is currently. The levee would be <br />approximately 6200-feet long and would be built to an <br />elevation of 7548. A typical section of the tieback levee is <br />shown in Figure 9. Riprap protection should be provided along <br />a short length of the levee near the river. <br /> <br />I <br /> <br />2. Alternate 'B' <br /> <br />Tieback levee Alternate 'B' continues northerly along the <br />river from the Carroll Addition and ties back to high ground <br />from the northern boundary of the Ri verwood Estates. <br />Approximately 4300-feet of levee reconstruction and new levee <br />construction would be required along this alignment. The <br />tieback levee would extend approximately 1900-feet, at <br />el evation 2548, from the river and tie into natural ground <br />near the abandoned irrigation ditch west of Riverwood Estates. <br />Riprap slope protection would be required along approximately <br /> <br />~ <br />~ <br /> <br />, <br /> <br />-23- <br />