§ 19A-2-4-242. Specific standards.

A.

In all areas of special flood hazards the following provisions are required:

1.

Residential Construction - new construction and substantial improvement of any residential structure shall have the lowest floor (including basement) elevated at least two (2) feet above the base flood elevation. A registered professional engineer, architect, or land surveyor shall submit a certification to the floodplain administrator that the standard of this subsection is satisfied before a building permit is issued for above-slab (foundation) construction. An additional certificate shall also be submitted prior to the issuance of a certificate of occupancy.

2.

Nonresidential Construction - new construction and substantial improvements of any commercial, industrial or other nonresidential structure shall have the lowest floor (including basement) elevated at least two (2) feet above the base flood elevation. A registered professional engineer, architect, or land surveyor shall submit a certification to the floodplain administrator that the standard of this subsection is satisfied before a building permit is issued for above-slab (foundation) construction. An additional certificate shall also be submitted prior to the issuance of a certificate of occupancy.

3.

Enclosures - new construction and substantial improvements, with fully enclosed 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 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 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; and

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.

4.

Fill and/or Development. For single-family residences fill and/or development may be allowed in flood fringe and areas of shallow flooding upon approval of plans submitted by a professional engineer, registered in the State of Oklahoma, showing that no fill shall encroach on the floodway. For all other development, fill and/or development may be allowed in flood fringe and areas of shallow flooding upon approval of plans and engineering calculations submitted by a professional engineer, registered in the State of Oklahoma, showing that the fill and/or development shall not cause an increase in flood levels during the base flood discharge to an extent causing existing upstream structures that currently flood to be flooded to a greater depth or causing existing upstream structures that currently do not flood to begin to flood. When preparing the plans and engineering calculations, the engineer must take into account any fill and/or development that has already been permitted in the flood fringe and areas of shallow flooding. Additionally, the following regulations shall apply when the flood fringe or area of shallow flooding sought for development or fill is adjacent to a regulatory floodway on the same property for which the development or fill is required:

a.

The applicant will retain at his cost a land surveyor, registered in the State of Oklahoma, to delineate the floodway boundary on the proposed site to prevent encroachment or any fill material or development in the floodway area;

b.

The land surveyor shall do an actual field survey to determine the floodway delineation line. The land surveyor shall also supervise the installation of monuments on the floodway boundary line. The monuments shall consist of a two-inch heavy gauge metal post being buried in the ground two (2) feet and set in concrete with six (6) feet above ground. The monuments will be set at the intersection of all the property lines on the requested site and at a minimum of fifty (50) foot intervals or at angular points, whichever is closer. The monuments shall be painted a caution orange;

c.

A survey map with the appropriate seal indicating the locations of the monuments set in relationship to property lines by distances and bearings shall be submitted to the city engineer by a land surveyor, registered in the State of Oklahoma, after installation of the monuments and prior to fill;

d.

No special flood hazard development permit or any other permit that allows fill shall be issued by the code official until these monuments have been constructed and the survey map prepared by a land surveyor, registered in the State of Oklahoma, has been approved by the floodplain administrator;

e.

The monuments shall be maintained in place by the applicant until the development site is completed and the floodplain administrator approves the removal of the monuments. In new subdivisions the monuments shall remain in place and be maintained by the property owner until all building construction and landscaping is completed; and that they permit the automatic entry and exit of floodwaters; and

f.

This subsection shall apply to all types of development on sites adjacent to the floodway to include applications for subdivisions, fill sites, or building permits.

5.

Critical Facilities. Critical facilities due to their importance in maintaining the health, safety and welfare of the community during periods of heavy rain and when flooding is prevalent must remain accessible and operational. Therefore, new critical facilities are prohibited in any regulatory special flood hazard area including the area identified as the 500-Year (0.2%) Floodplain on the adopted FIRM.

6.

Manufactured Homes:

a.

Require that all manufactured homes to be placed within Zone A on the Comanche County FIRM shall be installed using methods and practices that minimize flood damage and have the bottom of the I-beam elevated at two (2) feet above the base flood elevation. For the purposes of this requirement, manufactured homes must be elevated and anchored to resist flotation, collapse, or lateral movement. This requirement is in addition to applicable state and local anchoring requirements for resisting wind forces. The home shall be installed by a licensed installer according to Oklahoma state law and compliance herewith shall be certified in writing to the floodplain administrator by said installer prior to habitation of the manufactured home.

b.

Require that manufactured homes that are placed or substantially improved within Zone AE on the Comanche County FIRM on sites (i) outside of a manufactured home park or subdivision, (ii) in a new manufactured home park or subdivision, (iii) in an expansion to an existing manufactured home park or subdivision, or (iv) in an existing manufactured home park or subdivision on which a manufactured home has incurred "substantial damage" as a result of a flood, be elevated on a permanent foundation such that the bottom of the I-beam for the manufactured home is elevated at least two (2) feet above the base flood elevation and be securely anchored to an adequately anchored foundation system to resist flotation, collapse, and lateral movement. A licensed installer shall install the home in accordance with state law and compliance herewith shall be certified in writing to the floodplain administrator by said installer prior to habitation of the manufactured home.

c.

Require that manufactured homes be placed or substantially improved on sites in an existing manufactured home park or subdivision within Zone AE on the Comanche County FIRM that are not subject to the provisions of paragraph (6) of this section be elevated so that the bottom of the I-beam of the manufactured home is at least two (2) feet above the base flood elevation and be securely anchored to an adequately anchored foundation system to resist flotation, collapse, and lateral movement. A licensed installer shall install the home in accordance with state law and compliance herewith shall be certified in writing to the floodplain administrator by said installer prior to habitation of the manufactured home.

7.

Recreational Vehicles - Require that recreational vehicles placed on sites within Zones A and AE on the Comanche County FIRM either:

a.

Be on the site for fewer than one hundred eighty (180) consecutive days,

b.

Be fully licensed and ready for highway use, or

c.

Meet the permit requirements of Section 19A-2-2-223, and the elevation and anchoring requirements for "manufactured homes" in paragraph (6) of this section. 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.

8.

Accessory Structure - Accessory structures to be placed on sites within Zones A and AE on the Comanche County FIRM shall comply with the following:

a.

The structure shall be unfinished on the interior;

b.

The structure shall be used only for parking and limited storage;

c.

The structure shall not be used for human habitation. Prohibited activities or uses include but are not limited to working, sleeping, living, cooking, or restroom use;

d.

Service facilities such as electrical and heating equipment must be elevated to or above the BFE;

e.

The structure shall be constructed and placed on the building site so as to offer the minimum resistance to the flow of floodwaters;

f.

The structure shall be designed to have low flood damage potential and constructed with flood resistance materials;

g.

The structure shall be firmly anchored to prevent flotation, collapse, and lateral movement;

h.

Floodway requirements must be met in the construction of the structure;

i.

Openings to relieve hydrostatic pressure during a flood shall be provided below the BFE; and

j.

The structure shall be located so as not to cause damage to adjacent and nearby structures.

B.

Standards for Subdivisions:

1.

The applicant for a special flood hazard development permit for any subdivision located in Zones A and AE shall generate the base flood elevation data for that subdivision.

2.

All subdivisions including the placement of manufactured home parks and subdivisions shall have adequate drainage provided to reduce exposure to flood hazards.

3.

All subdivisions including the placement of manufactured home parks and subdivisions shall have public utilities and facilities such as sewer, gas, electrical and water systems located and constructed to minimize or eliminate flood damage.

4.

No portion of a proposed subdivision shall reflect new structures or fill in the floodway. Portions in the flood fringe or areas of shallow flooding shall be allowed only when it can be shown through engineering calculations submitted by a professional engineer, registered in the State of Oklahoma, that the proposed portions would not cause an increase in flood levels during the base flood discharge to an extent causing existing upstream structures that currently flood to be flooded to a greater depth or causing existing upstream structures that currently do not flood to begin to flood. When preparing the plans and engineering calculations, the engineer must take into account any fill and/or development that has already been permitted in the flood fringe and areas of shallow flooding. If portions are allowed in the flood fringe or areas of shallow flooding, those portions in the flood fringe or areas of shallow flooding on which structures are to be built shall provide for adequate fill to permit lowest floor elevations two (2) feet above the base flood.

C.

Standards for Areas of Shallow Flooding (AO Zones):

1.

Located within the areas of special flood hazard established in Section 19A-2-1-208, are areas designated as shallow flooding. These areas have special flood hazards associated with flood depths of one to three (3) feet where a clearly defined channel does not exist, where the path of flooding is unpredictable, and where velocity flow may be evident. Such flooding is characterized by ponding or sheet flow; therefore, the following provisions apply:

a.

All new construction and substantial improvements of residential structures have the lowest floor (including basement) elevated two (2) feet above the base flood elevation or the highest adjacent grade at least as high as the depth number specified in feet on the community's FIRM (at least two (2) feet if no depth number is specified).

b.

All new construction and substantial improvements of non-residential structures have the lowest floor (including basement) elevated two (2) feet above the base flood elevation or the highest adjacent grade at least as high as the depth number specified in feet on the community's FIRM (at least two (2) feet if no depth number is specified).

c.

A registered professional engineer or architect shall submit a certification to the floodplain administrator that the standards of this Section, as proposed in Section 19A-2-2-223 are satisfied.

d.

Require within Zone AO adequate drainage paths around structures on slopes, to guide flood waters around and away from proposed structures.

e.

Fill. Plans shall be submitted by a professional engineer, registered in the State of Oklahoma, showing that there will be no encroachment on the floodway under the provisions established in Subsection A4 of this section.

D.

Floodways.

1.

The following provisions shall apply to floodways:

a.

Encroachments, including but not limited to fill, new construction, substantial improvements and other development are prohibited within the adopted 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 City of Lawton during the occurrence of the base flood discharge.

b.

If (C)(1)(a) above is satisfied, all new construction and substantial improvements shall comply with all applicable flood hazard reduction provisions of Division 19A-2-4.

c.

The City of Lawton may permit encroachments within the adopted floodway that would result in an increase in base flood elevations, provided that the applicant for the development permit complies with all of 44 CFR Section 65.12.

(Ord. 2004-35, Amended, 08/24/2004; 98-18, Added, 05/26/1998)

(Ord. No. 09-21, § 23, 6-23-2009)