Okla. Admin. Code § 785:55-3-2

Current through Vol. 42, No. 4, November 1, 2024

Section 785:55-3-2 - Development in the regulatory floodplain with base flood elevations determined

(a)Applicability of section. In addition to the criteria and requirements set forth in 785:55-3-1 and 785:55-3-4 herein, all developments within the regulatory floodplain where base flood elevations have been determined shall comply with the criteria and requirements of this section.

(b)Use of base flood elevations. The Board shall obtain, review and utilize any base flood elevation and floodway data available from a federal, state, or other source, including data developed pursuant to 785:55-3-1(g), as criteria for requiring that new construction, substantial improvements, or other development in the regulatory floodplain meets the requirements of these Rules as applicable.

(c)Floor and floodproof elevations. The applicant shall obtain and provide the Board with the elevation (in relation to mean sea level) of the lowest floor (including basement) of all new and substantially improved structures. If the structure has been floodproofed in accordance with (i)(2) and (j) of this section, the applicant shall obtain and provide the Board with the elevation (in relation to mean sea level) to which the structure was floodproofed.

(d)Flood carrying capacity of altered watercourse. The Board shall assure that the flood carrying capacity within the altered or relocated portion of any watercourse is maintained.

(e)Manufactured home installation in general. All manufactured homes which are to be placed within a regulatory floodplain shall be installed using methods and practices which 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 to be limited to, use of over-the-top frame ties to ground anchors. This requirement is in addition to applicable state and local anchoring requirements for resisting wind forces.

(f)Manufactured home with permanent foundations. anufactured homes that are placed or substantially improved on sites within a regulatory floodplain shall be elevated on a permanent foundation such that the lowest floor of the manufactured home is elevated at least one (1) foot above the base flood elevation and be securely anchored to an adequately anchored foundation system to resist flotation, collapse and lateral movement where the manufactured home is located as follows:

(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.

(g)Manufactured homes without permanent foundations. Manufactured homes to be placed or substantially improved on sites in an existing manufactured home park or subdivision within regulatory floodplains that are not subject to the provisions of (f) of this section shall be elevated so that either:

(1) The lowest floor of the manufactured home is at or 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 to resist flotation, collapse and lateral movement.

(h)Other residential structures. All new construction and substantial improvements of residential structures within the regulatory floodplain shall have the lowest floor (including basement) elevated at least one (1) foot above the base flood elevation.

(i)Non-residential structures. All new construction and substantial improvements of non-residential structures within regulatory floodplains shall:

(1) Have the lowest floor (including basement) elevated at or above the base flood elevation; or

(2) Together with attendant utility and sanitary facilities, be designed so that below the base flood level the structure is watertight with wall substantially impermeable to the passage of water and with structural components having the capability of resisting hydrostatic and hydrodynamic loads and effects of buoyancy.

(j)Non-residential floodproofing. Where a non-residential structure is intended to be made watertight below the base flood elevation, the following shall apply:

(1) A Registered Professional Engineer or Architect shall develop and/or review structural design, specifications, and plans for the construction, and shall certify that the design and methods of construction are in accordance with accepted standards of practice for meeting the applicable provisions of (i)(2) of this section; and

(2) A record of such certificates which includes the specific elevation (in relation to mean sea level) to which such structures are floodproofed shall be maintained by the Board.

(3) Floodproofing for non-residential structures will be required only when the other aforementioned techniques for flood protection are impossible or impractical. Floodproofing measures shall be designed consistent with the base flood elevation for the particular area, flood velocities, durations, rate of rise, hydrostatic and hydrodynamic forces, and other factors associated with the regulatory flood. The Board may require that the applicant submit a plan or document certified by a Registered Professional Engineer or Licensed Architect that the floodproofing measures are consistent with the base flood elevation and associated flood factors for the particular area. Floodproofing measures which may be required include but are not limited to the following:

(A) Construction with materials and utility equipment resistant to flood damage.

(B) Anchorage to resist flotation and lateral movement.

(C) Installation of watertight doors, bulkheads and shutters or similar methods of construction.

(D) Reinforcement of walls to resist water pressures.

(E) Use of paints, caulks, or other substances to reduce seepage of water through walls.

(F) Addition of mass or weight to structures to resist flotation.

(G) Installation of pumps to lower water levels in structures.

(H) Construction of water supply and waste treatment systems so as to prevent the entrance of floodwaters.

(I) Pumping facilities or comparable practices for subsurface drainage systems for buildings, to relieve external foundation wall and basement flood pressures.

(J) Construction to resist rupture or collapse caused by water pressure or floating debris.

(K) Installation of valves or controls on sanitary and storm drains which will permit the drains to be closed to prevent backup of sewage and storm waters into the buildings or structures. Gravity draining of basements may be eliminated by mechanical devices.

(L) Location of all electrical equipment, circuits, and installed electrical appliances to assure they are above the base flood elevation.

(k)Enclosed areas below lowest floor. For all new construction and substantial improvements:

(1) Fully enclosed areas below the lowest floor that are usuable 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 the entry and exit of floodwaters.

(2) 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 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.

(B) The bottom of all openings shall be no higher than one foot above grade.

(C) Openings may be equipped with screens, louvers, valves, or other coverings or devices provided that they permit the automatic entry and exit of floodwaters.

(l)Recreational vehicles. Recreational vehicles placed on sites within regulatory floodplains shall:

(1) Be on the site for fewer than 180 consecutive days.

(2) Be fully licensed and ready for highway use. A recreational vehicle will be considered ready for highway use if it is on its wheels or jacking system, if attached to the site only by quick disconnect type utilities and security devices, and has no permanently attached additions; or

(3) Meet the permit requirements of 785:55-1-4 and the elevation and anchoring requirements for "manufactured homes" in (f) of this section.

Okla. Admin. Code § 785:55-3-2

Amended at 10 Ok Reg 3369, eff 6-25-93; Amended at 14 Ok Reg 2808, eff 7-1-97