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<br />. <br /> <br />. <br /> <br />. <br /> <br />The differenee in elevation between the ground at the low point on the "spillover" ridge and the <br />ground at the top of the railroad embankment is approximately 5 feet. That low point is <br />approximately 2.5 feet lower than the lO-year water surface elevation eomputed by EPl and <br />approximately 6 feet lower than the 100-year water surfaee elevation eomputed by EPL A spill that <br />was either 2.5 feet deep (lO-year flow) or 6 feet deep (lOO-year flow) would be substantial. It is <br />likely that taking into aeeount the effeet of spills over the low point will result in signifieant <br />ehanges both for the 10-year flood and for the 100-year flood. For that reason, the revised FIRM is <br />deemed to be aeeeptable only as approximate floodplain information. <br /> <br />Any development in the south side approximate floodplain will need a detailed floodplain analysis <br />to assure that the efJeets of spills over the low point of the ridge have been appropriately <br />eonsidered. On the north side of Otis, but still along the Southwest Drainage, where the flood <br />eontrol projeet was eonstrueted, the CWCB used the Norton, Underwood & Lamb map to update <br />the floodplain to properly refleet that projeet. The CWCB also did make a ehange to the town <br />eorporate limits in the southeast eorner of Otis, with the help of the town clerk, to more <br />appropriately represent floodprone areas within the eurrent town boundaries. It is expeeted that the <br />town will eonduet the neeessary hydraulie analysis to prepare a detailed floodplain map to replaee <br />the revised FIRM in the near future. <br /> <br />The Town of Otis should regulate the approximate floodplains on a ease-by-ease basis. An <br />approximate floodplain analysis ean be submitted by a developer or development proponent for the <br />allowable eases. Those allowable eases include development sueh as open spaee, agrieulture, farm <br />bridges, pole barns and individual residential struetures. A detailed floodplain analysis must be <br />performed by a professional engineer and submitted by the development proponent for all other <br />projeets. The use of approximate floodplain information is not appropriate for development <br />involving residential subdivisions greater than 50 lots or oceurring on sites greater 5 aeres, <br />eommereial eonstruetion, industrial eonstruetion, eonstruetion of publie faeilities, or eonstruetion of <br />flood eontrol faeilities. <br /> <br />Copies of the FIRM, prepared by FEMA, and the revised FIRM, prepared by the CWCB, are <br />included in Appendiees 3 and 4. <br /> <br />8 <br />