(A) Residential structures.
(1) Elevation on fill. Structures erected, constructed, reconstructed, altered, or moved on fill within the Flood Fringe District shall be placed so that the lowest floor, as defined in § 151.013, is elevated at or above the Regulatory Flood Protection Elevation (RFPE). The finished fill elevation shall be at or above the elevation associated with the base flood plus any stage increases that result from designation of a floodway. Fill must extend at the same elevation at least 15 feet beyond the outside limits of the structure. Elevations must be certified by a registered professional engineer, land surveyor or other qualified person designated by the Zoning Administrator. Elevation methods alternative to these fill standards are subject to a conditional use permit, as provided in § 151.062(A) (Figure 1 below). Construction of this type shall only be permitted in locations where the natural ground is no lower than three feet below the base flood elevation.
Figure 1: Overview of Fill Standards for Residential Structures.
(B) Nonresidential principal structures. Nonresidential principal structures must meet one of the following construction methods:
(1) Elevation on fill. Structures may be elevated on fill, meeting the standards in division (A) above. Fill for nonresidential structures is not required to be extended 15 feet beyond the outside limits of the structure.
(2) Alternative elevation methods.
(a) Structures may be elevated using methods alternative to the fill standards in division (A) above. Such methods include the use of blocks, pilings (Figure 2 below), filled stem walls (Figure 3 below), or internally-flooded enclosed areas (Figure 4 below) such as crawl spaces, attached garages, or tuck under garages.
Figure 2: Blocks or Pilings Figure 3: Filled Stem Walls Figure 4: Internally Flooded Enclosed Area
Designs accomm odating for internall y-flooded enclosed areas must be certified by a registered professional engineer or architect, or meet or exceed the standards detailed in FEMA Technical Bulletin 1, as amended, as well as the following standards:
(a) The lowest floor, as defined in § 151.013, shall be elevated at or above the Regulatory Flood Protection Elevation (RFPE).
(b) The floor of the enclosed area must be at or above the exterior grade on at least one side of the structure.
(c) To allow for the equalization of hydrostatic pressure, there shall be a minimum of two openings below the base flood elevation on at least two sides of the structure. The bottom of all openings shall be no higher than one foot above grade. The openings shall have a minimum net area of not less than one square inch for every square foot of enclosed area subject to flooding, have a net area of not less than one square inch for every square foot of enclosed area subject to flooding, and shall allow automatic entry and exit of floodwaters without human intervention.
(d) Internally flooded enclosed areas shall only be used for the parking of vehicles, building access, or storage. Bathrooms and toilet rooms shall not be allowed. Such areas shall be subject to a deed-restricted non-conversion agreement as well as periodic inspections with the issuance of any permit.
(3) Dry floodproofing. Structures having watertight enclosed basements or spaces below the Regulatory Flood Protection Elevation (RFPE) must meet the following standards:
(a) Walls must be substantially impermeable to the passage of water, with structural components having the capacity of resisting hydrostatic and hydrodynamic loads and effects of buoyancy, at least up to the Regulatory Flood Protection Elevation (RFPE);
(b) Must meet the standards of FEMA Technical Bulletin 3, as amended; and
(c) A registered professional engineer or architect shall be required to certify that the design and methods of construction meet the standards detailed in this section.
(C) Accessory structures. All accessory structures must meet the following standards:
(1) Structures shall not be designed or used for human habitation.
(2) Structures will have a low flood damage potential.
(3) Structures with fewer than two rigid walls, such as carports, gazebos, and picnic pavilions, may be located at an elevation below the Regulatory Flood Protection Elevation (RFPE).
(4) Structures with two or more rigid walls, must meet one of the following construction methods:
(a) Wet floodproofing. Structures may be floodproofed in a way to accommodate internal flooding. Such structures shall constitute a minimal investment not to exceed 576 square feet in size, one-story in height, and shall only be used for parking and storage. To allow for the equalization of hydrostatic pressure, there shall be a minimum of two openings on at least two sides of the structure and the bottom of all openings shall be no higher than one foot above grade. The openings shall have a minimum net area of not less than one square inch for every square foot of enclosed area subject to flooding, and shall allow automatic entry and exit of floodwaters without human intervention.
(b) Elevation on fill. Structures may be elevated on fill, meeting the standards in division (A) above. Fill is not required to be extended 15 feet beyond the outside limits of the structure.
(c) Alternative elevation methods. Structures may have their lowest floor elevated above the Regulatory Flood Protection Elevation (RFPE) through methods alternative to the fill standards in division (C)(4)(b) above, and must meet the standards in division (B)(2) above.
(d) Dry floodproofing. Structures may be dry-floodproofed, or watertight, meeting the standards in division (B)(3) above.
(D) All new principal structures must provide vehicular access no lower than one foot below the Base Flood Elevation (BFE), unless a flood waming/emergency evacuation plan has been approved by the city.
(E) Any facilities used by employees or the general public must be designed with a flood warning system acceptable to the city that provides adequate time for evacuation, or be designed to ensure that within the area inundated during the base flood event, the depth (in feet) multiplied by the velocity (in feet per second) is less than four.
(Ord. 406, passed 11-27-1989; Ord. 607, passed 7-8-2024)