Lafayette Municipal Code Art. 4 Standards for Flood Hazard Reduction

In all areas of special flood hazards the standards set forth in this article are required.

(Ord. No. 684, § 2(Exh. 2), 4-10-2023)

(a) All new construction and substantial improvements shall be adequately anchored to prevent flotation, collapse or lateral movement of the structure resulting from hydrodynamic and hydrostatic loads, including the effects of buoyancy.

(b) All manufactured homes shall meet the anchoring standards of Section 6-1838.

(Ord. No. 684, § 2(Exh. 2), 4-10-2023)

(a) All new construction and substantial improvements shall be constructed:

(1) With flood resistant materials as specified in FEMA Technical Bulletin TB 2-93, and utility equipment resistant to flood damage;

(2) Using methods and practices that minimize flood damage;

(3) 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; and if

(4) Within Zone AO or Zone AH, adequate drainage paths shall be provided around structures on slopes to guide floodwaters around and away from proposed structures.

(Ord. No. 684, § 2(Exh. 2), 4-10-2023)

(See Section 6-1804 definitions for "basement," "lowest floor," "new construction," "substantial damage" and "substantial improvement.")

(a) Residential construction, in cases of new or complete reconstruction, shall have the lowest floor, including basement,

(1) In an AO zone, elevated above the highest adjacent grade to a height exceeding the depth number specified in feet on the FIRM by at least two feet, or elevated at least four feet above the highest adjacent grade if no depth number is specified.

(2) In an A zone, elevated at least two feet above the base flood elevation, as determined by the community; the base flood elevation shall be determined by one of the methods in Section 6-1823(b).

(3) In all other zones, elevated at least two feet above the base flood elevation.

Upon completion of the structure, the elevation of the lowest floor including the basement shall be certified by a registered professional engineer or surveyor, and verified by the community building inspector, to be properly elevated. Such certification and verification shall be provided to the city engineer.

(b) Residential construction, in cases of substantial improvement, shall have the lowest floor, including basement:

(1) In an AO zone, elevated above the highest adjacent grade to a height equal to or exceeding the depth number specified in feet on the FIRM, or elevated at least two feet above the highest adjacent grade if no depth number is specified.

(2) In an A zone, elevated to or above the base flood elevation; said base flood elevation shall be determined by one of the methods in Section 6-1823(b).

(3) In all other zones, elevated to or above the base flood elevation.

Upon completion of the structure, the elevation of the lowest floor including the basement shall be certified by a registered professional engineer or surveyor, and verified by the community building inspector, to be properly elevated. Such certification and verification shall be provided to the city engineer.

(c) Nonresidential construction, new or substantial improvement, shall either be elevated in conformance with Section 6-1834(a) or (b), together with attendant utility and sanitary facilities:

(1) Be floodproofed so that below the elevation recommended in Section 6-1834(a) or (b), the structure is watertight with walls substantially impermeable to the passage of water;

(2) Have structural components capable of resisting hydrostatic and hydrodynamic loads and effects of buoyancy; and

(3) Be certified by a registered professional engineer or architect that the standards of Section 6-1834(c) are satisfied. Such certifications shall be provided to the city engineer.

(d) All new construction and substantial improvements, fully enclosed areas below the lowest floor (excluding basement) that are usable solely for parking of vehicles, building access or storage, and which are subject to flooding, shall be designed to automatically equalize hydrostatic flood forces on exterior walls by allowing for the entry and exit of floodwaters. Designs for meeting this requirement shall follow the guidelines in FEMA Technical Bulletins TB 1-93 and TB 7-93, and must exceed the following minimum criteria:

(1) A minimum of two openings having a total net area of not less than one square inch for every square foot of enclosed area subject to flooding shall be provided. The bottom of all openings shall be no higher than one foot above grade. Openings may be equipped with screens, louvers, valves or other coverings or devices, provided that they permit the automatic entry and exit of floodwaters; or

(2) Be certified by a registered professional engineer or architect.

(e) Manufactured homes shall meet the standards in this section and also the standards in Section 6-1838.

(Ord. No. 684, § 2(Exh. 2), 4-10-2023)

(a) The storage or processing of materials that are in time of flooding buoyant, flammable or explosive or could be injurious to human, animal or plant life is prohibited.

(b) 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.

(Ord. No. 684, § 2(Exh. 2), 4-10-2023)

(a) All new and replacement water supply and sanitary sewage systems shall be designed to minimize or eliminate:

(1) Infiltration of floodwaters into the system, and

(2) Discharge from systems into floodwaters.

(b) On-site waste disposal systems shall be located to avoid impairment to them or contamination from them during flooding.

(Ord. No. 684, § 2(Exh. 2), 4-10-2023)

(a) All preliminary subdivision proposals shall identify the flood hazard area and the elevation of the base flood.

(b) All subdivision plans will provide the elevation of proposed structure(s) and pad(s). If the site is filled above the base flood elevation, the lowest floor and pad elevations shall be certified by a registered professional engineer or surveyor and shall be provided to the city engineer.

(c) All subdivision proposals shall be consistent with the need to minimize flood damage.

(d) All subdivision proposals shall have public utilities and facilities such as sewer, gas, electrical and water systems located and constructed to minimize flood damage.

(e) All subdivision proposals shall provide adequate drainage to reduce exposure to flood hazards.

(Ord. No. 684, § 2(Exh. 2), 4-10-2023)

(a) All manufactured homes that are placed or substantially improved, within Zones A1-30, AH and AE on the community's flood insurance rate map, on sites located:

(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 a site upon which a manufactured home has incurred "substantial damage" as the result of a flood,

shall be elevated on a permanent foundation such that the lowest floor of the manufactured home is elevated:

(1) At least two feet above the base flood elevation for cases of new placement; or

(2) At least above the base flood elevation for cases of substantial improvement; and be securely fastened to an adequately anchored foundation system to resist flotation, collapse and lateral movement.

(b) All manufactured homes to be placed or substantially improved on sites in an existing manufactured home park or subdivision within zones A1-30, AH and AE, on the community's flood insurance rate map that are not subject to the provisions of paragraph Section 6-1838(a) will be securely fastened to an adequately anchored foundation system to resist flotation, collapse, and lateral movement, and be elevated so that either the

(1) Lowest floor of the manufactured home is:

(A) At least two feet above the base flood elevation for new placement; or

(B) At least above the base flood elevation for substantial improvement; or

(2) 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.

(c) Upon the completion of the structure, the elevation of the lowest floor including basement shall be certified by a registered professional engineer or surveyor, and verified by the community building inspector to be properly elevated. Such certification and verification shall be provided to the floodplain administrator.

(d) All recreational vehicles placed on sites within zones A1-30, AH and AE on the community's flood insurance rate map will either:

(1) Be on the site for fewer than 180 consecutive days, and be fully licensed and ready for highway use; a recreational vehicle is ready for highway use if it is on its wheels or jacking system, is attached to the site only by quick disconnect type utilities and security devices, and has no permanently attached additions; or

(2) Meet the permit requirements of Article 3 of this chapter and the elevation and anchoring requirements for manufactured homes in Section 6-838(a).

(Ord. No. 684, § 2(Exh. 2), 4-10-2023)

Located within areas of special flood hazard established in Section 6-1812 are areas designated as floodways. Since the floodway is an extremely hazardous area due to the velocity of floodwaters which carry debris, potential projectiles, and erosion potential, the following provisions apply.

(a) Encroachment, including fill, new construction, substantial improvements, and other new development is prohibited, unless certification by a registered professional engineer is provided demonstrating that the encroachment will not result in any increase in (the base) flood elevation during the occurrence of the base flood discharge.

(b) No manufactured home may be placed in a floodway.

(c) If Section 6-1839(a) is satisfied, all new construction, substantial improvements, and other proposed new development shall comply with all applicable flood hazard reduction provisions of this article.

(Ord. No. 684, § 2(Exh. 2), 4-10-2023)

Flood-related erosion-prone areas in Lafayette are typically creeks and should comply with Article 5 of this chapter.

(Ord. No. 684, § 2(Exh. 2), 4-10-2023)