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Portsmouth, Virginia, Code of Ordinances: PART II -CODE -Chapter 14.1 FLOOD PROTECTION Conditional Letter of Map Revision, and receives the approval of the Federal Emergency Management Agency. (3) The following provisions shall apply within an A zone [44 CFR 60.3(b)J. a. The Approximated Floodpiain District shall be that floodplain area for which no detailed flood profiles or elevations are provided, but where a one hundred {104}-year floodplain boundary has been approximated. Such areas are shown as Zane A on the maps accompanying the FIS. For these areas, the base flood elevations and floodway information from federal, state, and other accep#able sources shall be used, when available. Where the specific one percent annual chance flood elevation cannot be determined for this area using other sources of data, such as the U. S. Army Gorps of Engineers Floodpiain Information Reports, U. S. Geological Survey Flood-Prone Quadrangles, etc., then the applicant for the proposed use, development and/or activity shall determine this base flood elevation. For development proposed in the approximate floodplain the applicant must use technical methods that correctly reflect currently accepted non-detailed technical concepts, such as point on boundary, high water marks, or detailed methodologies hydrologic and hydraulic analyses. Studies, analyses, computations, etc,, shall be submitted in sufficient detail to allow a thorough review by the Floodpiain Administrator. b. The Floodpiain Administrator reserves the right to require a hydrologic and hydraulic analysis for any development. When such base flood elevation data is utilized, the lowest floor shall be elevated to the design flood elevation {DFE}. c. During the permitting process, the Floodpiain Administrator shall obtain: 1 } The elevation of the lowest floor (including HVAG, all duct work, and the basement} of ail new and substantially improved structures; and 2} If the structure is non-residential has been flood-proofed in accordance with the requirements of this article, the elevation (in relation to mean sea level} to which the structure has been flood-proofed. Residential structures shall not be flood-proofed. d. Base flood elevation data shall be obtained from other sources or developed using detailed methodologies comparable to those contained in a FIS for subdivision proposals and other proposed development proposals (including manufactured home parks and subdivisions} that exceed fifty Tots or five acres, whichever is the lesser. (4) The following provisions shall apply within an AO zone [44 CFR 60.3(c}J. a. All new construction and substantial improvement of residen#iai structures shall have the lowest floor, including basement, elevated to or above the flood depth specified on the FIRM, above the highest adjacent grade at least as high as the depth number specified in feet on the FIRM. If no flood depth number is specifed, the lowest floor, including basement, shall be eleva#ed no less than two feet above the highest adjacent grade, 94