(A) General provisions.
(1) Alteration or relocation of a watercourse.
(a) A watercourse or drain way shall not be altered or relocated in any way that in the event of a base flood or more frequent flood will alter the flood-carrying characteristics of the watercourse or drain way to the detriment of upstream, downstream or adjacent locations.
(b) No alteration or relocation shall be made until all adjacent communities that may be affected by such action and the State Department of Natural Resources have been notified and all applicable permits obtained. Evidence of such notification shall be submitted to the Federal Emergency Management Agency.
(2) Encroachments.
(a) When proposing to permit any of the following encroachments, the standards in this subsection (A)(2) shall apply:
1. To any development in Zone A without a designated floodway that will cause a rise of more than one foot in the base flood elevation; or
2. To the alteration or relocation of a stream.
(b) The applicant shall:
1. Apply to FEMA for conditional approval of such action via the conditional letter of map revision process (as per 44 C.F.R. § 65.12) prior to the permit for the encroachments; and
2. Supply the fully approved package to the Floodplain Administrator, including any required notifications to potentially affected property owners.
(B) Elevation and floodproofing requirements.
(1) Residential structures. In Zone A, all new construction and substantial improvements shall have the lowest floor, including basement, elevated to or above two feet above the base flood elevation.
(2) Nonresidential structures.
(a) In Zone A, all new construction and substantial improvements shall have the lowest floor, including basement, elevated to or above two feet above the base flood elevation or, together with attendant utility and sanitary facilities, floodproofed so that below two feet above the base flood elevation:
1. The structure is watertight with walls substantially impermeable to the passage of water; and
2. The structure has structural components with the capability of resisting hydrostatic and hydrodynamic loads and effects of buoyancy.
(b) A registered professional engineer or architect shall certify that the standards of this subsection (B) are satisfied. A floodproofing certificate shall be provided to the Floodplain Administrator as set forth herein.
(3) Critical facilities. New construction or substantial improvement of any critical facility is prohibited in all areas of the floodplain and the 0.2% annual chance floodplain unless all of the following provisions are met.
(a) No feasible alternative site exists for the construction of an equivalent facility within the corporate or extraterritorial jurisdiction boundaries of the city.
(b) The facility has the lowest floor, including basement, of all structures elevated to one foot above the 0.2% annual chance flood elevation or, together with attendant utility and sanitary facilities, floodproofed so that below one foot above the 0.2% annual chance flood elevation:
1. The structure is watertight with walls substantially impermeable to the passage of water;
2. The structure has structural components with the capability of resisting hydrostatic and hydrodynamic loads and effects of buoyancy; and
3. A registered professional engineer or architect shall certify that the standards of the subsection are satisfied. Such certification shall be provided to the Floodplain Administrator as set forth herein.
(c) If the 0.2% annual chance floodplain is not identified, the facility shall have the lowest floor, including basement, elevated to three feet above the base flood elevation or be floodproofed to three feet above the base flood elevation with the standards in subsection (B)(3)(b) above.
(d) The facility has at least one access road connected to land outside the 0.2% annual chance floodplain that is capable of carrying emergency support vehicles and the top of the access road is no lower than the 0.2% annual chance flood elevation.
(4) Space below lowest floor.
(a) All new construction and substantial improvements shall not have fully enclosed areas below the base flood elevation.
(b) Fully enclosed areas below the lowest floor (excluding basements) and below the base flood elevation shall be used solely for the parking of vehicles, building access or limited storage of readily removable items.
(c) Fully enclosed areas below the lowest floor (excluding basements) and below the base flood elevation shall be designed to automatically equalize hydrostatic flood forces on exterior walls by allowing for the entry and exit of floodwaters. The size of such enclosed areas shall not exceed 299 square feet except for buildings where the minimum clearance height of the enclosed area is less than seven feet. Designs for meeting this requirement must either be certified by a registered professional engineer or architect or meet or exceed the following minimum criteria.
1. A minimum of two openings having a net total area of not less than one square inch for every one square foot of enclosed space are required.
2. The bottom of all openings shall not be higher than one foot above grade.
3. Openings may be equipped with screens, louvers, valves or other coverings or devices provided that they allow the automatic entry and exit of floodwaters.
(5) Appurtenant structures. Structures accessory to a principal building may have the lowest floor below one foot above base flood elevation provided that the structure complies with the following requirements.
(a) The structure shall not be used for human habitation.
(b) The use of the structure must be limited to parking of vehicles or storage of items readily removable in the event of a flood warning.
(c) The floor area shall not exceed 900 square feet.
(d) The structure shall have a low damage potential.
(e) The structure must be adequately anchored to prevent flotation, collapse or other lateral movement.
(f) The structure shall be designed to automatically provide for the entry and exit of floodwaters for the purpose of equalizing hydrostatic forces. Designs for meeting this requirement must either be certified by a registered professional engineer or architect or meet or exceed the following minimum criteria:
1. A minimum of two openings having a net area of not less than one square inch for every one square foot of enclosed space are required.
2. The bottom of all openings shall not be higher than one foot above grade.
3. Openings may be equipped with screens, louvers, valves or other coverings or devices provided they allow the automatic entry and exit of floodwaters.
(g) No utilities shall be installed in the structure, except electrical fixtures which must be elevated or floodproofed to one foot above base flood elevation.
(h) The structure shall be constructed and placed on the building site so as to offer the minimum resistance to the flow of floodwaters.
(i) If the structure is converted to another use, it must be brought into full compliance with the minimum standards governing such use.
(6) Manufactured homes.
(a) All manufactured homes are required to be placed or substantially improved within floodplains on sites:
1. Outside of a manufactured home park or subdivision;
2. In a new manufactured home park or subdivision;
3. In an expansion to an existing manufactured home park or subdivision; or
4. In an existing manufactured home park or subdivision on which a manufactured home has incurred substantial damage as the result of a flood, be elevated on a permanent foundation such that the lowest floor of the manufactured home is at or above two feet above the base flood elevation and be securely anchored to an adequately anchored foundation system in accordance with the provisions of this section.
(b) Manufactured homes are required to be placed or substantially improved on sites in an existing manufactured home park or subdivision within special flood hazard areas that are not subject to the provisions of subsection (B)(6)(a) above be elevated so that either:
1. The lowest floor of the manufactured home is at or above two feet above the base flood elevation; or
2. The manufactured home chassis is supported by reinforced piers or other foundation elements of at least equivalent strength that are no less than 36 inches in height above grade; and be securely anchored to an adequately anchored foundation system in accordance with the provisions of subsection (B)(6)(d) below.
(c) New manufactured home parks of five acres or 50 lots, whichever is less, shall follow the standards of subsection (C)(8) below.
(d) All manufactured homes shall be anchored to resist flotation, collapse or lateral movement. Manufactured homes must be anchored in accordance with local building codes or FEMA guidelines. In the event that over-the-top ties to ground anchors are used, the following specific requirements (or their equivalent) shall be met.
1. Over-the-top ties shall be provided at each of the four corners of the manufactured home, with two additional ties per side at intermediate locations and manufactured homes less than 50 feet long requiring one additional tie per side.
2. Frame ties shall be provided at each corner of the manufactured home with five additional ties per side at intermediate points and manufactured homes less than 50 feet long requiring four additional ties per side.
3. Any additions to the manufactured home shall be similarly anchored.
(7) Existing structures.
(a) The provisions of this article do not require any changes or improvements to be made to lawfully existing structures. However, when an improvement is made to a structure in the floodplain, a floodplain development permit is required and the provisions of subsections (B)(7)(b) and (B)(7)(c) below shall apply.
(b) Any addition, alteration, reconstruction or improvement of any kind to an existing structure where the costs of which would equal or exceed 50% of the pre-improvement market value shall constitute a substantial improvement and shall fully comply with the provisions of this article.
(c) Any addition, alteration, reconstruction or improvement of any kind to an existing structure that will change the compliance requirements of the building shall require applicable documentation including an elevation certificate, floodproofing certificate or no rise certification.
(C) Design and construction standards.
(1) Anchoring. All buildings or structures shall be firmly anchored to prevent flotation, collapse or lateral movement of the structure resulting from hydrodynamic and hydrostatic loads, including the effects of buoyancy.
(2) Building materials and utilities.
(a) All buildings or structures shall be constructed with materials and utility equipment resistant to flood damage. All buildings or structures shall also be constructed by methods and practices that minimize flood and flood-related damages.
(b) All buildings or structures shall be constructed with electrical, heating, ventilation, plumbing, 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.
(3) Drainage. Within Zones AO and AH, adequate drainage paths around structures on slopes shall be required in order to guide floodwaters around and away from proposed structures.
(4) Water supply and sanitary sewer systems.
(a) All new or replacement water supply and sanitary sewer systems shall be located, designed and constructed to minimize or eliminate flood damages to such systems and the infiltration of floodwaters into the systems.
(b) All new or replacement sanitary sewage systems shall be designed to minimize or eliminate discharge from the system into floodwaters.
(c) On-site waste disposal systems shall be located and designed to avoid impairment to them or contamination from them during flooding.
(5) Other utilities. All other utilities such as gas lines, electrical, telephone and other utilities shall be located and constructed to minimize or eliminate flood damage to such utilities and facilities.
(6) Storage of materials.
(a) The storage or processing of materials that are in time of flooding buoyant, flammable, explosive or could be injurious to human, animal or plant life is prohibited.
(b) The storage of other material or equipment may be allowed if not subject to major damage by floods and firmly anchored to prevent flotation or if readily removable from the area within the time available after flood warning.
(7) Recreational vehicles. Recreational vehicles to be placed on sites within the floodplain shall:
(a) Be on site for fewer than 180 consecutive days;
(b) Be fully licensed and ready for highway use, which shall mean it is on its wheels or jacking system, is attached to the site by only quick-disconnect type utilities and security devices and has no permanently attached additions; and
(c) Meet the permit requirements and the elevation and anchoring requirements for manufactured homes of this article.
(8) Subdivisions. Subdivision proposals and other proposed new development, including manufactured home parks or subdivisions, shall require assurance that:
(a) All such proposals are consistent with the need to minimize flood damage;
(b) All public utilities and facilities such as sewer, gas, electrical and water systems are located, elevated and constructed to minimize or eliminate flood damage;
(c) Adequate drainage is provided so as to reduce exposure to flood hazards; and
(d) Proposals for development (including proposals for manufactured home parks and subdivisions) of five acres or 50 lots, whichever is less, where base flood elevation data are not available, shall be supported by hydrologic and hydraulic analyses that determine base flood elevations and floodway information. The analyses shall be prepared by a licensed professional engineer in a format required by FEMA for conditional letters of map revision and a letters of map revision.
(Ord. 964, passed 6-7-2022)