A. General Provisions: No final subdivision plat shall be approved nor shall any site development or building permit be issued for property located within the area of shallow flooding or area of special flood hazard until the proposed development, construction, substantial improvement or work under permit complies with the following criteria:
1. All proposals for new development, new construction or substantial improvements to existing structures within the floodplain area, including prefabricated and manufactured homes, must:
a. Be designed or modified and adequately anchored to prevent flotation, collapse or lateral movement of the structure resulting from hydrodynamic and hydrostatic loads, including the effects of buoyancy;
b. Be constructed with materials resistant to flood damage;
c. Utilize construction methods and practices that will minimize flood damage; and
d. Be constructed with electrical, heating, ventilation, plumbing and air conditioning equipment and other service facilities that are designed and/or located so as to prevent water from entering or accumulating within the components during conditions of flooding.
2. All proposals for construction or improvements (including replacements) shall be designed:
a. To minimize or eliminate infiltration of floodwaters into water supply and sanitary sewage systems;
b. To minimize and eliminate discharges from the sanitary sewage system into floodwater; and
c. With any on site waste disposal systems designed, located, and constructed to minimize or eliminate flood damage to the system or contamination from the system during flooding.
3. The buildings or structures shall be constructed and placed on the building site so as to offer the minimum obstruction to the flood or floodwaters. Whenever possible, buildings or structures shall be constructed with longitudinal axis parallel to the direction of flood flow. So far as practicable, buildings or structures shall be placed approximately on the same flood flow lines as those of adjoining structures.
4. Within the AH and AO zones, adequate drainage paths are required around structures on slopes to guide floodwaters around and away from proposed structures.
5. All new construction and substantial improvements that fully enclose areas below the lowest floor that are usable solely for parking of vehicles, building access or storage in an area other than a basement and which are subject to flooding shall be designed to automatically equalize hydrostatic flood forces on exterior walls by allowing for entry and exit of floodwaters. Designs for meeting this requirement must either be certified by the applicant's registered professional engineer or architect or must have the following minimum criteria:
a. A minimum of two (2) flood openings having a total net area of not less than one square inch per one square foot of enclosed area subject to flooding shall be provided;
b. The bottom of all flood openings shall be no higher than one foot (1') above grade; and
c. Flood openings may be equipped with screens, louvers, valves or other coverings or devices; provided, that they permit the automatic entry and exit of floodwaters.
6. All subdivision proposals and other proposed new development, including residential manufactured home parks, shall:
a. Be consistent with the need to minimize flood damage;
b. Have public utilities and facilities such as sewer, gas, electrical, and water systems located and constructed to minimize or eliminate flood damage;
c. Provide adequate drainage to reduce exposure to flood hazards; and
d. Include BFE data for each lot on the preliminary plat if the subdivision or proposed new development contains fifty (50) lots or five (5) acres (whichever is less); and
e. Include the mapped flood hazard zones from the effective FIRM.
7. Fill within an area of special flood hazard shall result in no net loss of natural floodplain storage or increase in water surface elevations during the base flood and shall be offset by compensatory storage.
B. Residences:
1. New construction or substantial improvements of residential structures in the A, A1-30, AH or AE zones of the Weber County, Utah, and incorporated areas FIRM shall have the lowest floor (including basement) elevated to, or above, the BFE;
2. All new construction and substantial improvements of residential structures within the AO or AH zones of the Weber County, Utah, and incorporated areas FIRM shall have the lowest floor (including basement) elevated above the highest adjacent grade or above the depth number specified on the Weber County, Utah, and incorporated areas FIRM, which shall be at least two feet (2') if no depth number is specified;
C. Nonresidential Construction:
1. All new development, new construction and substantial improvements of nonresidential structures within any A1-30, AE and AH zones on the Weber County, Utah, and incorporated areas FIRM shall have the lowest floor (including basement) elevated to or above the BFE, or together with the attendant utility and sanitary facilities, be designed so that below the base flood level the structure is watertight with walls substantially impermeable to passage of water and with structural components that have the capacity of resisting hydrostatic and hydrodynamic loads and effects of buoyancy. Floodproofing may be utilized to meet the above standard. Where floodproofing is utilized:
a. The applicant's registered professional engineer or licensed architect shall certify that the floodproofing design and construction methods comply with 44 CFR 60.3(c)(3)(ii) and associated building codes and are adequate, according to accepted engineering standards, to withstand the flood depths, pressure velocities, impact and uplift factors and other factors associated with the base flood; and
b. A record of said certificates (including calculations) indicating the specific elevation (in relation to mean sea level) to which said structures are floodproofed shall be maintained by the building official with the copy of the building or other permits.
2. All new construction and substantial improvements of nonresidential structures within the AO or AH zones on the Weber County, Utah, and incorporated areas FIRM shall have the lowest floor (including basement) elevated above the highest adjacent grade to or above the depth number specified in feet on the Weber County, Utah, and incorporated areas FIRM (at least two feet (2') if no depth number is specified) or, together with the attendant utility and sanitary facilities, be completely floodproofed to that level to meet the floodproofing standard specified in Subsection C1.
D. Manufactured Home Parks; Manufactured Homes:
1. Manufactured homes shall be elevated on a permanent foundation so that the lowest floor of the home is elevated to or above the BFE and the home is securely anchored to an adequately anchored foundation system to resist flotation, collapse and lateral movement if the home is to be placed, or substantially improved, on any site in an A zone, or on the following sites in zones A1-30, AH, and AE:
a. Outside of a manufactured home park or subdivision;
b. In a new manufactured home park or subdivision;
c. In an expansion to an existing manufactured home park or subdivision; or
d. In an existing manufactured home park or subdivision on which a manufactured home has incurred substantial damage as a result of a flood.
2. Manufactured homes to be placed or substantially improved on sites in existing manufactured home parks or subdivisions which were created before the implementation of the flood regulations and are within zones A1-30, AH, AO, and AE and that are not subject to the provisions of Subsection D1 shall be elevated so that either:
a. The lowest floor of the manufactured home is at or above the BFE; or
b. The manufactured home chassis is supported by reinforced piers or other foundation elements of at least equivalent strength that are not less than thirty six inches (36") in height above the grade and is securely anchored to an adequately anchored foundation system to resist flotation, collapse and lateral movement.
3. When required by this chapter, methods of anchoring a manufactured home may include, but are not limited to, use of over the top or frame ties to ground anchors. Anchoring installed to meet the requirements of this chapter is in addition to applicable state and local anchoring requirements for resisting wind forces.
E. Recreational Vehicles: In all areas of special flood hazard, recreational vehicles are required to either:
1. Be on the site for fewer than one hundred eighty (180) consecutive days, be fully licensed and be ready for highway use, on its wheels or jacking system, attached to the site only by quick disconnect type utilities and security devices, and have no permanently attached structures or addition; or
2. Meet the requirements of being placed on a pad elevated to or above the BFE and be securely anchored to an adequate anchored foundation system to resist flotation, collapse and lateral movement.
F. Approval: Notwithstanding any other provision of this chapter, if the city first applies for a conditional FIRM revision through FEMA's CLOMR process, fulfills the requirements for such revision as established under the provisions of 44 CFR Chapter 1, Section 65.12 of the NFIP regulations, and receives the approval of the federal insurance administrator, certain development in zones A1-30, AE and AH which increase the water surface elevation of the base flood by more than one foot (1') may be approved.
(Ord. 2015-21, 5-26-2015; amd. Ord. 2023-61, 11-14-2023)