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<br />. Generally, when an appellant is required <br />to submit delineations of floodplain <br />boundaries, both the 100- and SOO-year <br />floodplain boundaries must be <br />submitted. If the FIS includes analyses of <br />only the 100-year flood for the flooding <br />source that is the subject of the appeal, <br />only the 100-year floodplain boundaries <br />must be submitted. The boundaries <br />should be shown on a topographic map <br />whose scale and contour interval are <br />sufficient to provide reasonable <br />accuTacy. <br /> <br />. To support an appeal based on the <br />effects of earthfill levees or similar <br />structures, the appellant must submit <br />the following data to show that the <br />structural stability, operation, and <br />maintenance requirements of Section <br />6S.10 of the N FIP regulations have been <br />met: <br /> <br />1. Freeboard -- For a riverine levee, <br />evidence that the levee provides a <br />minimum of 3 feet of freeboard <br />above the BFE <br /> <br />2. Freeboard -- For a coastal levee, <br />evidence that the levee provides a <br />minimum of 1 foot of freeboard <br />above the height of the 1-percent <br />wave or the maximum wave runup <br />(whichever is greater) associated <br />with the 100-year stillwater surge <br />elevation, but in no case less than 2 <br />feet of freeboard above the 100-year <br />stillwater surge elevation <br /> <br />3. Closures n Evidence that shows that <br />all drainage structures that <br />penetrate the levee are fitted with <br />closure devices that are structural <br />parts of the levee during operation <br />and designed according to sound <br />engineering practice <br /> <br />4. Erosion Protection -- An engineering <br />analysis that demonstrates that no <br />appreciable erosion of the levee <br />embankment can be expected <br />during the 100- yearflood <br /> <br />16 <br /> <br />S. Stability -- An engineering analysis <br />that evaluates the stability of the <br />levee embankment and foundation <br /> <br />6. Settlement -- An engineering <br />analysis that assesses the potential <br />for, and magnitude of, losses of <br />freeboard that may resu It from <br />settlement of the levee and that <br />demonstrates that the mini mum <br />required freeboard will be <br />maintained <br /> <br />7. OpeTations A formal levee <br />operation plan <br /> <br />8. Maintenance A formal levee <br />maintenance plan <br /> <br />Exceptions to the minimum freeboard <br />requirements cited in Items 1 and 2 for <br />riverine and coastal levees may be <br />approved under certain conditions. Any <br />request for an exception must be <br />supported by appropriate engineering <br />analyses which show that even with the <br />lesser freeboard, a high level of certainty <br />for 1 OO-year flood protection exists. For <br />riverine levees, the supporting analyses <br />must evaluate the uncertainty in the <br />estimated BFE and must assess, at a <br />minimum, the statistical confidence <br />limits of the 100-year peak dischaTge; <br />stage-discharge relationships for floods <br />larger than the 100-year flood; and the <br />sources, potential, and magnitude of <br />debris, sediment, and ice accumulation <br />that may affect those relationships. The <br />analyses must also show that the levee <br />will remain structurally stable during the <br />base flood, when such additional <br />loading conditions are imposed. <br />Freeboards of less than 2 feet will not be <br />accepted. <br /> <br />For coastal levees, the supporting <br />analyses must evaluate the uncertainty <br />in the estimated base flood loading <br />conditions. Particular emphasis must be <br />placed on the effects of wave attack and <br />overtopping on the stability of the levee. <br />FreeboaTds of less than 2 feet above the <br />computed stillwater surge elevation will <br />not be accepted. <br />