City of Vandalia, MO Article IV Provisions For Flood Hazard Reduction

Section 425.070 General Standards.

[R.O. 1991 § 425.070; Ord. No. 1018 § I, 7-13-2004; Ord. No. 1030 §§ I – II, 4-12-2005]

A. General Standards.

1. No permit for floodplain development shall be granted for new construction, substantial improvements and other improvements, including the placement of manufactured homes, within any unnumbered or numbered A Zones and AE Zones, unless the conditions of this Section are satisfied.

2. All areas identified as unnumbered A Zones on the FIRM are subject to inundation of the 100-year flood; however, the base flood elevation is not provided. Development within unnumbered A Zones is subject to all provisions of this Chapter. If Flood Insurance Study data is not available, the community shall obtain, review and reasonably utilize any base flood elevation or floodway data currently available from Federal, State or other sources.

3. Until a floodway is designated, no new construction, substantial improvements or other development, including fill, shall be permitted within any numbered A Zone or AE Zone on the FIRM, unless it is demonstrated that the cumulative effect of the proposed development, when combined with all other existing and anticipated development, will not increase the water surface elevation of the base flood more than one (1) foot at any point within the community.

4. All new construction, subdivision proposals, substantial improvements, prefabricated structures, placement of manufactured homes, and other developments shall require:

a. Design or adequate anchorage to prevent flotation, collapse or lateral movement of the structure resulting from hydrodynamic and hydrostatic loads, including the effects of buoyancy;

b. Construction with materials resistant to flood damage;

c. Utilization of methods and practices that minimize flood damages;

d. All electrical, heating, ventilation, plumbing, air-conditioning equipment and other service facilities be designed and/or located so as to prevent water from entering or accumulating within the components during conditions of flooding;

e. New or replacement water supply systems and/or sanitary sewage systems be designed to minimize or eliminate infiltration of floodwaters into the systems and discharges from the systems into floodwaters, and on-site waste disposal systems be located so as to avoid impairment or contamination; and

f. Subdivision proposals and other proposed new development, including manufactured home parks or subdivisions, located within special flood hazard areas are required to ensure that:

(1) All such proposals are consistent with the need to minimize flood damage;

(2) All public utilities and facilities, such as sewer, gas, electrical and water systems, are located and constructed to minimize or eliminate flood damage;

(3) Adequate drainage is provided so as to reduce exposure to flood hazards; and

(4) All proposals for development, including proposals for manufactured home parks and subdivisions, greater than five (5) acres or fifty (50) lots, whichever is lesser, include within such proposals base flood elevation data.

5. Agricultural Structures. Structures used solely for agricultural purposes in connection with the production, harvesting, storage, drying or raising of agricultural commodities, including the raising of livestock, may be constructed at-grade and wet-flood-proofed provided there is no human habitation or occupancy of the structure; the structure is of single-wall design; there is no permanent retail, wholesale or manufacturing use included in the structure; a variance has been granted from the floodplain management requirements of this Chapter; and a floodplain development permit has been issued.

6. Storage, Material And Equipment.

a. The storage or processing of materials within the special flood hazard area that are in time of flooding buoyant, flammable, 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, if firmly anchored to prevent flotation, or if readily removable from the are within the time available after a flood warning.

(1) Accessory Structures. Structures used solely for parking and limited storage purposes, not attached to any other structure on the site, of limited investment value, and not larger than four hundred (400) square feet may be constructed at-grade and wet-flood-proofed, provided there is no human habitation or occupancy of the structure; the structure is of single-wall design; a variance has been granted from the standard floodplain management requirements of this Chapter; and a floodplain development permit has been issued.

B. Specific Standards. In all areas identified as unnumbered and numbered A Zones and AE Zones, where base flood elevation data have been provided as set forth in Article IV, Section 425.070(A)(2), the following provisions are required:

1. Residential Construction. New construction or substantial improvement of any residential structures, including manufactured homes, shall have the lowest floor, including basement, elevated to one (1) foot above base flood level.

2. Non-Residential Construction. New construction or substantial improvement of any commercial, industrial or other non-residential structures, including manufactured homes, shall have the lowest floor, including basement, elevated to one (1) foot above the base flood level or, together with attendant utility and sanitary facilities, be floodproofed so that below the base flood elevation the structure is watertight with walls substantially impermeable to the passage of water and with structural components having the capability of resisting hydrostatic and hydrodynamic loads and effects of buoyancy. A registered professional engineer or architect shall certify that the standards of this Subsection are satisfied. Such certification shall be provided to the Floodplain Administrator as set forth in Article III, Section 425.060(C)(9).

3. Require, for all new construction and substantial improvements, that fully enclosed areas below lowest floor used solely for parking of vehicles, building access, or storage in an area other than a basement and that 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 must either be certified by a registered professional engineer or architect or meet or exceed the following minimum criteria:

a. A minimum of two (2) openings having a total net area of not less than one (1) square inch for every square foot of enclosed area subject to flooding shall be provided; and

b. The bottom of all opening shall be no higher than one (1) 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.

C. Manufactured Homes.

1. All manufactured homes to be placed within all unnumbered and numbered A Zones and AE Zones on the community's FIRM shall be required to be installed using methods and practices that minimize flood damage. For the purposes of this requirement, manufactured homes must be elevated and anchored to resist flotation, collapse or lateral movement. Methods of anchoring may include, but are not limited to, use of over-the-top or frame ties to ground anchors.

2. Require manufactured homes that are placed or substantially improved within unnumbered or numbered A Zones and AE Zones on the community's FIRM on sites:

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 the result of a flood, be elevated on a permanent foundation such that the lowest floor of the manufactured home is elevated to one (1) foot above the base flood elevation and be securely attached to an adequately anchored foundation system to resist flotation, collapse and lateral movement.

3. Require that manufactured homes be placed or substantially improved on sites in an existing manufactured home park or subdivision within all unnumbered and numbered A Zones and AE Zones on the community's FIRM, that are not subject to the provisions of Article IV, Section 425.070(C)(2) of this Chapter, be elevated so that either:

a. The lowest floor of the manufactured home is at one (1) foot above the base flood elevation; or

b. Manufactured home chassis is supported by reinforced piers or other foundation elements of at least equivalent strength that are no less than thirty-six (36) inches in height above grade and be securely attached to an adequately anchored foundation system to resist flotation, collapse and lateral movement.

D. Floodway. If a community determines these are areas of special flood hazard that may be defined as floodway, through the use of base flood elevation and floodway data available from a Federal, State or other source, including data developed pursuant to Article IV, Section 425.070(A)(4)(f)(iv) and determines this data is suitable as criteria for requiring that new construction, substantial improvements, or other development in Zone A, the community must meet the standards below:

1. Adopt a regulatory floodway based on the principle that the area chosen for the regulatory floodway must be designed to carry the waters of the base flood without increasing the water surface elevation of that flood more than one (1) foot at any point.

2. Prohibit encroachments, including fill, new construction, substantial improvements, and other development, within the adopted regulatory floodway unless it has been demonstrated through hydrologic and hydraulic analyses performed in accordance with standard engineering practice that the proposed encroachment would not result in any increase in flood levels within the community during the occurrence of the base flood discharge.

E. Recreational Vehicles. Require that recreational vehicles placed on sites within all unnumbered and numbered A Zones and AE Zones on the community's FIRM either:

1. Be on the site for fewer than one hundred eighty (180) consecutive days; or

2. Be fully licensed and ready for highway use*;. or

3. Meet the permitting, elevation and anchoring requirements for manufactured homes of this Chapter.

*A recreational vehicle is ready for highway use if it is on its wheels or jacking system, is attached to the side only by quick-disconnect type utilities and security devices and has no permanently attached additions.