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<br />Economic feasibility was estimated by plottin,g the minimum cost estimates presented in <br />Table 5-1 on each Figure. The cosf for a three foot wall and levee was 1.2 and 0.5 percent <br />respectively (expressed as a percentage of structure value). A five foot wall or levee was <br />estimated to cost 1.6 and 0.7 percent respectively. A comparison of minimum cost and damage <br />reduced shows a small levee (three feet and .five feet) to be economically feasible for all flood <br />hazard factors, all locations in the flood plain, and all type structures except a two story, no <br />basement structure. For this latter structure a three foot levee appears to be feasible below the <br />15 year flood plain and a five foot levee below the 20 year flood plain (seeFigures 5-3 and 5-7). <br />Above these locations feasibility depends upon the event at the first floor and flood hazard <br />factor. . <br /> <br />A small wall, because of its higher cost is somewhat less feasible. Protection of a one story, no <br />basement structl,lre appears to be feasible for both a three foot and five foot height below about <br />the 15 year flood plain, infeasible above the 25 year and questionable between the two. See <br />Figures 5-2 and 5-6. A two story, no basement structure appears feasible below about the 7 year, <br />infeasible above about the 15 year and questionable between the 7 and 15 year events at the first <br />floor. This is illustrated in Figures 5-3 and 5-7. Three foot and five foot walls are generally <br />economically feasible for one and two story structures with basements at any location in the <br />flood plain provided the flood hazard factor is less than about 8.0 feet. For higher flood hazard <br />factors economic feasibility varies with type structure, height of protection and location in flood <br />plain. <br /> <br />Advantages and Disadvantages <br />Table 5-2 summarizes several advantages and disadvantages of small walls or levees. <br /> <br />f <br />t <br />t <br />t <br />( <br />\ <br />\ <br />l <br />, <br />l <br />r <br />, <br />I <br />( <br />f <br />~ <br />~ <br />i <br />t <br />f <br />l <br />, <br />~ <br />1 <br />t' <br />( <br />" <br />( <br />.; <br />l <br />I <br />( <br /> <br />TABLE 5-2 <br /> <br />ADVANTAGES AND DISADVANTAGES OF PROTECTING <br />A NEW OR EXISTING STRUCTURE WITH A SMALL WALL OR LEVEE <br /> <br />Advantages <br /> <br />Not dependent upon the size, type, or <br />condition of property bei ng protected. <br /> <br />Protects property outside a strucwre. <br /> <br />C;an be aesthetically pleasing and provide <br />privacy and security in addition to" flood <br />protection. <br /> <br />Disadvantages <br /> <br />Dependent upon site conditions: Topo- <br />graphy, property lines, available space, soil <br />and ground water conditions, velocity and <br />depth of flooding, and location of flood <br />water relative to structure. <br /> <br />May require access openings which must be <br />closed during a flood. If the closures are <br />manual a warning time is necessary. <br /> <br />References <br /> <br />1. Dexter, James, "Planning a Program for Flood-Proofing Technology Transfer to Flood-Plain <br />Residents", Ph.d. Dissertation, Department of Civil Engineering, Georgia Institute of <br />Technology, 1977. <br /> <br />.. <br />( <br />r <br />f <br /> <br />r <br />( <br />f <br />I' <br />" <br />, <br />, <br />i <br />I <br />i <br /> <br />34 <br />