(A) Residential construction. New construction and substantial improvement of any residential structure (including manufactured homes) shall have the lowest floor elevated no lower than one (1) foot above the base flood elevation. No basements are permitted. Should solid foundation perimeter walls be used to elevate a structure, flood openings sufficient to automatically equalize hydrostatic flood forces, shall be provided in accordance with the elevated buildings requirements in division (D) below.
(B) Non-residential construction.
(1) New construction and substantial improvement of any commercial, industrial, or non-residential structure (including manufactured homes) shall have the lowest floor elevated no lower than one (1) foot above the level of the base flood elevation. Should solid foundation perimeter walls be used to elevate a structure, flood openings sufficient to automatically equalize hydrostatic flood forces, shall be provided in accordance with the elevated buildings requirements in division (D) below. No basements are permitted. Structures located in A-Zones may be floodproofed in lieu of elevation provided that all areas of the structure below the required elevation are watertight with walls substantially impermeable to the passage of water, using structural components having the capability of resisting hydrostatic and hydrodynamic loads and the effect of buoyancy.
(2) A registered, professional engineer or architect shall certify that the standards of this division are satisfied. Such certifications shall be provided to the official as set forth in the floodproofing certification requirements in § 5-6-22. A variance may be considered for wet-floodproofing agricultural structures in accordance with the criteria outlined in § 5-6-44. Agricultural structures not meeting the criteria of § 5-6-44 must meet the nonresidential construction standards and all other applicable provisions of this chapter. Structures that are floodproofed are required to have an approved maintenance plan with an annual exercise. The Local Floodplain Administrator must approve the maintenance plan and notification of the annual exercise shall be provided to it.
(C) Manufactured homes.
(1) Manufactured homes that are placed or substantially improved on sites outside a manufactured home park or subdivision, in a new manufactured home park or subdivision, in an expansion to an existing manufactured home park or subdivision, or in an existing manufactured home park or subdivision on which a manufactured home has incurred substantial damage as the result of a flood, must be elevated on a permanent foundation such that the lowest floor of the manufactured home is elevated no lower than 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.
(2) Manufactured homes that are to be placed or substantially improved on sites in an existing manufactured home park or subdivision that are not subject to the provisions for residential construction in division (A) above must be elevated so that the lowest floor of the manufactured home is elevated no lower one (1) foot than above the base flood elevation, and be securely anchored to an adequately anchored foundation to resist flotation, collapse, and lateral movement.
(3) Manufactured homes shall be anchored to prevent flotation, collapse, and lateral movement. For the purpose of this requirement, manufactured homes must be anchored to resist flotation, collapse, and lateral movement in accordance with Section 40-29-10 of the South Carolina Manufactured Housing Board Regulations, as amended. Additionally, when the elevation requirement would be met by an elevation of the chassis thirty-six (36) inches or less above the grade at the site, the chassis shall be supported by reinforced piers or engineered foundation. When the elevation of the chassis is above thirty-six (36) inches in height an engineering certification is required.
(4) An evacuation plan must be developed for evacuation of all residents of all new, substantially improved or substantially damaged manufactured home parks or subdivisions located within flood-prone areas. This plan shall be filed with and approved by the Local Floodplain Administrator and the local Emergency Preparedness Coordinator.
(D) Elevated buildings. New construction and substantial improvements of elevated buildings that include fully enclosed areas below the lowest floor that are usable solely for the parking of vehicles, building access, or limited storage in an area other than a basement, and which are subject to flooding shall be designed to preclude finished space and be designed to automatically equalize hydrostatic flood forces on exterior walls by allowing for the entry and exit of floodwaters.
(1) Designs for complying with this requirement must either be certified by a professional engineer or architect or meet or exceed all of the following minimum criteria:
(a) Provide a minimum of two (2) openings on different walls having a total net area of not less than one (1) square inch for every square foot of enclosed area subject to flooding;
(b) The bottom of each opening must be no more than one (1) foot above the higher of the interior or exterior grade immediately under the opening;
(c) Only the portions of openings that are below the base flood elevation (BFE) can be counted towards the required net open area;
(d) Openings may be equipped with screens, louvers, valves, or other coverings or devices provided they permit the automatic flow of floodwaters in both directions;
(e) 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 of the building.
(2) Hazardous velocities. Hydrodynamic pressure must be considered in the design of any foundation system where velocity waters or the potential for debris flow exists, if flood velocities are excessive (greater than five (5) feet per second), foundation systems other than solid foundations walls should be considered so that obstructions to damaging flood flows are minimized.
(3) Enclosures below lowest floor.
(a) Access to the enclosed area shall be the minimum necessary to allow for parking of vehicles (garage door) or limited storage of maintenance equipment used in connection with the premises (standard exterior door) or entry to the living area (stairway or elevator).
(b) The interior portion of such enclosed area shall not be finished or partitioned into separate rooms, must be void of utilities except for essential lighting as required for safety, and cannot be temperature controlled.
(c) One (1) wet location switch and/or outlet connected to a ground fault interrupt breaker may be installed below the required lowest floor elevation specified in the specific standards outlined in divisions (A), (B) and (C) above.
(d) All construction materials below the required lowest floor elevation specified in the specific standards outlined in divisions (A), (B), (C) and (D) should be of flood- resistant materials.
(E) Floodways. Located within areas of special flood hazard established in § 5-6-4 are areas designated as floodways. The floodway is an extremely hazardous area due to the velocity of floodwaters that carry debris and potential projectiles and has erosion potential. The following provisions shall apply within such areas.
(1) No encroachments, including fill, new construction, substantial improvements, additions, and other developments shall be permitted unless:
(a) 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 the flood levels during the occurrence of the base flood. Such certification and technical data shall be presented to the Local Floodplain Administrator.
(b) A Conditional Letter of Map revision (CLOMR) has been approved by FEMA. A Letter of Map Revision must be obtained upon completion of the proposed development.
(3) No manufactured homes shall be permitted, except in an existing manufactured home park or subdivision. A replacement manufactured home may be placed on a lot in an existing manufactured home park or subdivision provided the anchoring and the elevation standards of division (C) above and the encroachment standards of division (E)(1) above are met.
(4) Permissible uses within floodways may include: general farming, pasture, outdoor plant nurseries, horticulture, forestry, wildlife sanctuary, game farm, and other similar agricultural, wildlife, and related uses. Also, lawns, gardens, play areas, picnic grounds, and hiking and horseback riding trails are acceptable uses, provided that they do not employ structures or fill. Substantial development of a permissible use may require a no-impact certification. The uses listed in this division are permissible only if and to the extent that they do not cause any increase in base flood elevations or changes to the floodway configuration.
(F) Recreational vehicles.
(1) A recreational vehicle is ready for highway use if it is:
(a) On wheels or jacking system;
(b) Attached to the site only by quick-disconnect type utilities and security devices; and
(c) Has no permanently attached additions.
(2) Recreational vehicles placed on sites shall either be:
(a) On site for fewer than one hundred eighty (180) consecutive days; or
(b) Be fully licensed and ready for highway use, or
(G) Map maintenance activities. The National Flood Insurance Program (NFIP) requires flood data to be reviewed and approved by FEMA. This ensures that flood maps, studies and other data identified in § 5-6-4 accurately represent flooding conditions so appropriate floodplain management criteria are based on current data. The following map maintenance activities are identified.
(1) Requirement to submit new technical data.
(a) For all development proposals that impact floodway delineations or base flood elevations, the community shall ensure that technical or scientific data reflecting such changes be submitted to FEMA as soon as practicable, but no later than six (6) months of the date such information becomes available. These development proposals include; but not limited to:
1. Floodway encroachments that increase or decrease base flood elevations or alter floodway boundaries;
2. Fill sites to be used for the placement of proposed structures where the applicant desires to remove the site from the special flood hazard area;
3. Alteration of watercourses that result in a relocation or elimination of the special flood hazard area, including the placement of culverts; and
4. Subdivision or large scale development proposals requiring the establishment of base flood elevations in accordance with § 5-6-32(A).
(b) It is the responsibility of the applicant to have technical data, required in accordance with this division (G), prepared in a format required for a Conditional Letter of Map Revision or Letter of Map Revision, and submitted to FEMA. Submittal and processing fees for these map revisions shall also be the responsibility of the applicant.
(c) The Local Floodplain Administrator shall require a Conditional Letter of Map Revision prior to the issuance of a floodplain development permit for:
1. Proposed floodway encroachments that increase the base flood elevation; and
2. Proposed development which increases the base flood elevation by more than one (1) foot in areas where FEMA has provided base flood elevations but no floodway.
(d) Floodplain development permits issued by the Local Floodplain Administrator shall be conditioned upon the applicant obtaining a Letter of Map Revision from FEMA for any development proposal subject to this division (G).
(2) Right to submit new technical data. The Floodplain Administrator may request changes to any of the information shown on an effective map that does not impact floodplain or floodway delineations or base flood elevations, such as labeling or planimetric details. Such a submission shall include appropriate supporting documentation made in writing by the local jurisdiction and may be submitted at any time.
(H) Accessory structures.
(1) A detached accessory structure or garage, the cost of which is greater than three thousand dollars ($3,000), must comply with the requirements as outlined in FEMA's Technical Bulletin 7-93 Wet Floodproofing Requirements or be elevated in accordance with divisions (A) and (D) above or dry floodproofed In accordance with division (B) above.
(2) If accessory structures of three thousand dollars ($3,000) or less are to be placed in the floodplain, the following criteria shall be met:
(a) Accessory structures shall not be used for any uses other than the parking of vehicles and storage;
(b) Accessory structures shall be designed to have low flood damage potential;
(c) Accessory structures shall be constructed and placed on the building site so as to offer the minimum resistance to the flow of floodwaters;
(d) Accessory structures shall be firmly anchored to prevent flotation, collapse and lateral movement of the structure;
(e) Service facilities such as electrical and heating equipment shall be installed in accordance with § 5-6-30(E);
(f) Openings to relieve hydrostatic pressure during a flood shall be provided below base flood elevation in conformance with division (D)(1) above; and
(g) Accessory structures shall be built with flood resistance materials in accordance with Technical Bulletin 2, Flood Damage-Resistant Materials Requirements, dated August 2008, and available from the Federal Emergency Management Agency. Class 4 and 5 materials, referenced therein, are acceptable flood-resistant materials.
(I) Swimming pool utility equipment rooms. If the building cannot be built at or above the BFE, because of functionality of the equipment then a structure to house the utilities for the pool may be built below the BFE with the following provisions:
(1) Meet the requirements for accessory structures in division (H) above;
(2) The utilities must be anchored to prevent flotation and shall be designed to prevent water from entering or accumulating within the components during conditions of the base flood.
(J) Elevators.
(1) Install a float switch system or another system that provides the same level of safety necessary for all elevators where there is a potential for the elevator cab to descend below the BFE during a flood per FEMA's Technical Bulletin 4-93 Elevator Installation for Buildings Located in Special Flood Hazard Areas.
(2) All equipment that may have to be installed below the BFE such as counter weight roller guides, compensation cable and pulleys, and oil buffers for traction elevators and the jack assembly for a hydraulic elevator must be constructed using flood-resistant materials where possible per FEMA's Technical Bulletin 4-93 Elevator installation for Buildings Located in Special Flood Hazard Areas.
(K) Fill. An applicant shall demonstrate that fill is the only alternative to raising the building to meet the residential and non-residential construction requirements of divisions (A) and (B) above, and that the amount of fill used will not affect the flood storage capacity or adversely affect adjacent properties. The following provisions shall apply to all fill placed in the special flood hazard area:
(1) Fill may not be placed in the floodway unless it is in accordance with the requirements in division (E)(1) above.
(2) Fill may not be placed in tidal or non-tidal wetlands without the required state and federal permits.
(3) Fill must consist of soil and rock materials only. A registered professional geotechnical engineer may use dredged material as fill only upon certification of suitability. Landfills, rubble fills, dumps, and sanitary fills are not permitted in the floodplain.
(4) Fill used to support structures must comply with ASTM Standard D-698, and its suitability to support structures certified by a registered, professional engineer.
(5) Fill slopes shall be no greater than two horizontal to one vertical. Flatter slopes may be required where velocities may result in erosion.
(6) The use of fill shall not increase flooding or cause drainage problems on neighboring properties.
(7) Fill may not be used for structural support in the coastal high hazard areas.
(8) Will meet the requirements of FEMA Technical Bulletin 10-01, Ensuring That Structures Built On Fill in or Near Special Flood Hazard Areas Are Reasonable Safe from Flooding.
(L) Standards for subdivision proposals and other development.
(1) All subdivision proposals and other proposed new development shall be consistent with the need to minimize flood damage and are subject to all applicable standards in these regulations.
(2) All subdivision proposals and other proposed new development shall have public utilities and facilities such as sewer, gas, electrical, and water systems located and constructed to minimize flood damage.
(3) All subdivision proposals and other proposed new development shall have adequate drainage provided to reduce exposure to flood damage.
(4) The applicant shall meet the requirement to submit technical data to FEMA in division (G) above when a hydrologic and hydraulic analysis is completed that generates base flood elevations.
(Ord. 18-06, passed 6-11-2018)