Flood hazard districts include: (1) flood plains, (2) areas of shallow flooding, (3) areas of special flood hazard, and (4) floodways. The development of these areas, where shown on flood hazard boundary maps, issued by the Federal Emergency Management Agency (FEMA) for Colleton County, may not occur where alternative locations exist due to the inherent hazards and risks involved. Where there is no alternative to a location in a flood hazard district, proposed development shall be regulated by the following.

A. General Development Standards.

1. New construction and substantial improvements of existing structures shall be anchored to prevent floatation, collapse, or lateral movement of the structure;

2. New construction and changes of existing structures below the minimum first floor elevation shall be constructed with materials and utility equipment resistant to flood damage;

3. New construction or substantial improvements of existing structures shall be constructed by methods and practices that minimize flood damage;

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

5. Manufactured homes shall be anchored to prevent floatation, 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. This standard shall be in addition to and consistent with applicable state requirements for resisting wind forces;

6. New and replacement water supply systems shall be designed to minimize or eliminate infiltration of flood waters into the system;

7. New and replacement sanitary sewerage systems shall be designed to minimize or eliminate infiltration of flood waters into the systems and discharges from the systems into flood waters;

8. On-site waste disposal systems shall be located and constructed to avoid impairment or contamination during flooding; and

9. Any alteration, repair, reconstruction, or improvement to a structure which is not in compliance with the provisions of this title, shall be undertaken only if non-conformity is not furthered, extended, or replaced.

B. Specific Development Standards. In all areas of special flood hazard where base flood evaluation data are available, the following shall be required.

1. Residential Construction. New construction or substantial improvement of any residential structure (including manufactured homes) shall have the lowest floor elevated no lower than one foot above the base flood elevation. A pre-construction and post-construction flood evaluation certificate shall be submitted. No basements are permitted. Should solid foundation perimeter walls be used to elevate a structure, creating a fully enclosed area, said enclosed area shall:

a. Be designed to preclude permanent living space;

b. Be useable solely for parking vehicles, building access, or storage; and

c. Include openings sufficient to facilitate unimpeded movement of floodwaters and/or be designed to automatically equalize hydrostatic flood forces on exterior walls by allowing for entry and exit of floodwaters.

Designs for complying with this requirement must either be certified by a professional engineer or architect or meet the following minimum criteria:

a. Provide a minimum of two openings on different walls having a total net area of not less than one square inch for every square foot of enclosed area subject to flooding;

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 they permit the automatic flow of floodwaters in both directions; and,

d. Fill placed around foundation walls must be graded so that the grade inside the enclosed area is equal to or higher than the adjacent grade outside the building on at least one side.

2. Nonresidential Construction. New construction or substantial improvements of any commercial, industrial, or nonresidential structure shall have the lowest flood elevated no lower than one foot above the level of the base flood elevation. No basements are permitted. Structures located in A-zones may be floodproofed in lieu of elevation are watertight with walls substantially impermeable to the passage of water, using structural components having the capability of resisting hydrostatic loads and the effect of buoyancy. A registered, professional engineer or architect shall certify that the standards of this subsection are satisfied. Agricultural structures may be wet-floodproofed in accord with Technical Bulletin 7-93, Wet Floodproofing Requirements for Structures Located in Special Flood Hazard Areas in Accordance with the National Flood Insurance Program, document number FIA-TB-7.

3. Temporary Development. All applicants for a temporary use must submit to the director of planning and facilities, prior to the issuance of a development permit, a written plan for the removal of any temporary use or structure in the event of a hurricane or flash flood warning notification. The plan shall be reviewed and approved in writing, and must include the following information:

a. A specified time for which the temporary use will be permitted,

b. The name, address, and phone number of the individual responsible for the removal of said use,

c. The time frame prior to the event at which any structure will be removed (i.e. minimum of seventy-two (72) hours before landfall of a hurricane or immediately upon flood warning notification),

d. A copy of a contract or other suitable instrument with a trucking company to insure the availability of removal equipment when needed,

e. Designation, accompanied by documentation, of a location outside the floodplain to which said temporary structure will be moved, and

f. A plan to restore the area to its natural condition once the temporary permit expires or the temporary use is terminated, whichever is first.

4. Accessory Structures. An accessory structure, the cost of which is greater than three thousand dollars ($3,000.00), must comply with the elevated structure requirements of this section. When accessory structures of three thousand dollars ($3,000.00) or less are to be placed in the floodplain, such structures shall:

a. Not be used for human habitation (including work, sleeping, living, cooking, or restroom areas); and

b. Be designed to have low flood damage potential, be constructed and placed on the building site so as to offer minimum resistance to floodwaters, and be firmly anchored to prevent floatation, collapse, or lateral movement.

5. Floodways. The following provisions shall apply within floodways:

a. No encroachments, including fill, new construction, substantial improvements, additions, or other developments shall be permitted unless it has been demonstrated through hydraulic analysis performed in accordance with standard engineering practice that the proposed encroachment would not result in any increase in the flood levels during the occurrence of a base flood.

b. Where no such increase is certified, new construction and substantial improvements may be permitted in compliance with the requirements of this section.

c. Permissible uses exempt from such certification include general farming, pasture, outdoor plant nurseries, horticulture, forestry, wildlife sanctuary, game farm, and other similar agricultural, wildlife, and related uses, lawns, gardens, play areas, picnic grounds, hiking and horseback riding trails, provided that they do not employ structures or fill.

6. Standards for Streams and/or Floodways Without Established Base Flood Elevations. Development contiguous to small streams where no flood data have been provided or where no floodways have been identified shall adhere to the following:

a. No encroachments, including fill, new construction, substantial improvements or new development shall be permitted within forty (40) feet of the stream bank unless certification with supporting technical data by a registered, professional engineer is provided demonstrating that such encroachments shall not result in any increase in flood levels during the occurrence of base flood discharge.

b. Where no such increase is certified, new construction and substantial improvements may be allowed within such areas provided all applicable provisions of this section are satisfied.

7. Standards for Subdivision Proposals.

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

b. All subdivision proposals shall have adequate drainage provided to reduce exposure to flood hazard; and,

c. Base flood elevation data shall be provided for subdivision proposals and other proposed developments greater than the lesser of five lots or five acres.

8. Standards for Areas of Shallow Flooding (AO Zones). Development within the areas subject to shallow flooding in the AO zone shall adhere to the general and specific development standards of this section.

C. Warning and Disclaimer of Liability. The degree of flood protection required by this chapter is based on scientific and engineering considerations. However, larger floods can and will occur on rare occasions. Therefore, this section shall not create liability on the part of Colleton County or by any officer or employee thereof for any flood damages that may result from reliance on this chapter or any administrative decision lawfully made thereunder. (Ord. 99-O-25 § 2.6, 1999)