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<br />5 <br /> <br />Comparison of "As-Built" to FIS Models <br /> <br />A comparison of the FIS models and BC's "as-built" models for the IOO-year floodplain <br />and floodway is shown in Appendix C, FEMA Fonn 4. <br /> <br />Water surface elevations are the same below the Ash Avenue bridge and above the 5th <br />Street bridge. The water surface elevations between the Ash Avenue bridge and the 5th Street <br />bridge reflect the construction of new bridges at Ash Avenue and 8th Street. The improved <br />bridge capacity limits backwater flooding and removes previously flooded lands and structures <br />from the lOO-year floodplain with subsequent reduction in the floodway. As indicated by the <br />comparison of elevations on Table 2, the average reduction in water surface elevation for the <br />lOO-year storm within the WPCF is 2-feet. <br /> <br />Floodplain and floodway limits, determined by the new models, are shown on Drawing <br />G-I enclosed at the back of this report. <br /> <br />Impacts on Proposed Construction <br /> <br />While 2-foot reductions in the floodplain elevations were realized by the new bridge <br />construction, the WPCF remains within the floodplain of the Poudre. Additionally, parts of the <br />WPCF remain within the revised floodway. Until channel improvements, such as the Warzyn <br />levees, are constructed, certain regulatory limitations will be placed on what the City can <br />construct for improvements. These are: <br /> <br />. No new structures can be constructed within the regulatory floodway. <br /> <br />. Existing structures within the floodway can be remodeled providing that the <br />"footprint" is not expanded and the cost of remodel is less that 50-percent of the <br />structure's market value. <br /> <br />. Construction can be done within the floodplain, outside of the floodway, <br />providing that the fIrst floor elevation is above the lOO-year water surface <br />elevation or the structure is floodproofed. <br /> <br />Construction opportunities at specific facility areas are: <br /> <br />I. Headworks. The headworks is located on an island within the floodplain, but is <br />above the floodplain and the floodway. ModifIcations can be made to the <br />headworks as long as the revised struclme remains outside of the floodway <br />boundary . <br /> <br />2. Primary Clarifiers. The primary clarifiers are located outside of the floodway <br />and are on naturally high ground above the lOO-year floodplain elevation. Any <br />required modifications can be made to this component. <br /> <br />j5,nIIJ\fif] ~mdi CiIlarlwea <br />; ~-, ,~--) t,:Plts <br /> <br />21/7387 <br />