Flood control plans shall be prepared according to the following guidelines prior to the submission of the plan to the county.
(A) Encroachment upon an identified major drainage channel and the adjacent overflow land shall be avoided. An easement, sufficient to accommodate the flow resulting from a storm with a 100-year return frequency, shall be provided, approved by the Planning Engineer as to width and course, to protect the carrying capacity of the channel and to provide working room for construction and maintenance. The easement shall be dedicated to the county.
(B) Whenever major drainage channel improvements are carried out, sodding, backsloping, cribbing and other bank protection shall be designed and constructed to control erosion for the anticipated conditions and flow resulting from a 100-year frequency rainfall. If the improvements involve significant alteration or relocation of the course of a major drainage channel, prior notification shall be given to adjacent communities and the South Carolina Water Resources Commission, with copies of the notification sent to the Federal Insurance Administrator.
(C) Design all culverts, bridges, and other drainage structures in accordance with the specifications and design standards of the Planning Engineer's office and predicate same on a 100-year frequency rainfall.
(D) Applicants shall obtain all necessary permits from those governmental agencies from which approval is required by state or federal law.
(E) The Planning Engineer shall review subdivision proposals and other proposed new developments to determine whether the proposals will be reasonably secure from the ravages of flooding. If any subdivision proposal or other proposed new development is in a flood-prone area, the Planning Engineer shall require the submission of the base flood elevation date, and any proposal shall be reviewed to assure that:
(1) All proposals are consistent with the need to minimize flood damage with the flood prone area;
(2) All public utilities and facilities, such as sewer, gas, electrical and water systems, are located and constructed to minimize or eliminate flood damage; and
(3) Adequate drainage is provided to reduce exposure to flood hazards.
(F) The applicant shall design new and replacement water and sewer systems within flood prone areas so as to prevent or eliminate infiltration of flood waters into the system. Septic tanks shall be located so that they are free from inundation by a 100-year flood.
(G) All new construction and substantial improvements of residential structures shall have the lowest floor, including basement, elevated to at least one (1) foot above the 100-year frequency flood elevation. If a building pad is used, the ground shall be sloped from the pad down to the 100-year frequency flood elevation over a distance of ten (10) feet or more feet.
(H) All new construction and substantial improvements of non-residential structures shall:
(1) Have the lowest floor, including basement, elevated to at least one (1) foot above the flood level of a flood with a return frequency of 100 years;
(2) Together with attendant utility and sanitary facilities, be designed so that below the elevation of a flood with a return frequency of 100 years, the structure is watertight with walls substantially impermeable to the passage of water and with structural components having the capability of resisting hydrostatic loads and effects of buoyancy; and
(3) Where floodproofing is utilized for a particular structure, a registered engineer or architect shall certify that the floodproofing methods are adequate to withstand the flood depths, pressure, velocities, impact, uplift forces and other factors associated with a flood with a return frequency of 100 years, and a record of the certificates shall be maintained in the Department of Planning and Development.
(I) For the purpose of determining applicable flood insurance risk premium rates, the county shall:
(1) Require that the elevation (mean sea level) of the lowest floor (including basement) of all new or substantially improved structures be provided and that notice be given if the structure includes a basement;
(2) Require that, if the structure has been floodproofed, the elevation (mean sea level) to which the structure was floodproofed be provided; and
(3) Maintain a public record of all information with the Department of Planning and Development.
(J) No encroachments, including fill, new construction, substantial improvements or other development resulting in an increase in the surface water elevation of the adopted regulatory floodway during the occurrence of a 100-year flood shall be permitted.
(K) Mobile home location and placement shall adhere to the following:
(1) No mobile home shall be permitted in the regulatory floodway;
(2) Mobile homes located in the floodplain shall be placed on compacted fill elevated to at least one (1) foot above the elevation of the 100-year flood; and
(3) Mobile homes located in the floodplain in accord with the above shall be secured with anchored tie-downs in accord with C.F.R. § 60.3(b)(8).
(L) New construction or substantial improvements of elevated buildings that include fully enclosed areas formed by foundation and other exterior walls below the base flood elevation shall be designed to preclude finished living space and designed to allow for the entry and exit of floodwaters to automatically equalize hydrostatic flood forces on exterior walls. Designs for complying with this requirement must either be certified by a professional engineer or architect or meet the following minimum criteria:
(1) Provide 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;
(2) The bottom of all openings shall be no higher than one (1) foot above grade; and
(3) Openings may be equipped with screens, louvers, valves or other coverings or devices provided they permit the automatic flow of floodwaters in both directions.
(M) Electrical, plumbing and other utility connections are prohibited below the base flood elevation.
(1985 Code, § 4, 4.20) Penalty, see § 157.999