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<br />2 <br /> <br />Our comparison of the proposed conditions model revealed increases and decreases in the BFEs compared <br />to the corrected effective model. The maximum increase in BFE, approximately 0.9 foot, will occur <br />approximately 500 feet upstream ofihe proposed E-470 bridges. All increases in BFEs based upon the <br />proposed project are contained within the proposed highway right-of-ways with the exception of 0.1 foot <br />increase at approximately 400 feet upstream of the 1 52nd A venue bridge. At this location, the increase in <br />BFE has been mitigated by an agreement between the City of Thomton and the affected property owner to <br />eliminate the increase in SFHA by filling the affected area. No insurable structures are located in areas <br />impacted by increased BFEs. The maximum decrease in BFE, approximately 0.7 foot, will occur at the <br />proposed E-470 bridges, The width of the SFHA will increase a maximum of approximately 700 feet <br />immediately downstream of the E-470 bridges, due to the construction of a wetland area. The width of the <br />SFHA will decrease approximately 900 feet at the proposed E-470 bridges. <br /> <br />The proposed conditions HEC-2 hydraulic computer modelincorporates the E-470 Highway project into <br />the corrected effective model. Our comparison of the proposed conditions model revealed increases in <br />BFEs when compared to the effective BFEs. The maximum increase in BFE, approximately 1.8 feet, will <br />occur just downstream of 156th Avenue. The width of the effective SFlfA will increase a maximlJDl of <br />approximately 700 feet immediately downstream of the E-470 bridges. The width of the SFHA will <br />decrease a maximum of approximately 900 feet at the proposed E-470 bridges. The effective floodway <br />width will increase a maximum of approximately 700 feet immediately downstream of the E-470 bridges. <br />The effective floodway width will decrease a maximum of approximately 800 feet at the proposed bridges. <br /> <br />Upon completion of the project, your community may submit the data listed below and request that we <br />make a final determination on revising the effective FIRM and FIS report. <br /> <br />. Detailed application and certification forms, which were used in processing this request, must be <br />used for requesting final revisions to the maps. Therefore, when the map revision request for the <br />area covered by this letter is submitted, Form 1, entitled "Revision Requester and Community <br />Official Form," must be included. (A copy of this form is enclosed.) <br /> <br />. The detailed application and certification forms listed below may be required if as-built conditions <br />differ from the preliminary plans. If required, please submit new forms (copies of which are <br />enclosed) or annotated copies of the previously submitted forms showing the revised information. <br /> <br />Form 3, entitled "Hydrologic Analysis Form" <br /> <br />Form 4, entitled "Riverine Hydraulic Analysis Form" <br /> <br />~ <br /> <br />Form 5, entitled "Riverine/Coastal Mapping Form" <br /> <br />Form 6, entitled "Channelization Form" <br /> <br />Form 7, entitled "Bridge/Culvert Form" <br /> <br />Hydraulic analyses, for as-built conditions, of the base flood; the floods having a 10-,2-, and <br />O.2-percent chance of being equaled or exceeded in any given year; and the regulatory floodway <br />must be submitted with Form 4, and a topographic work map showing the revised floodplain and <br />floodway boundaries must be submitted with Form 5. <br /> <br />. Effective June 1, 2000, FEMA revised the fee schedule for reviewing and processing requests for <br />