Fill is discouraged because storage capacity is removed from floodplains. Elevating buildings by other methods must be considered. An applicant shall demonstrate that fill is the only alternative to raising the building to at least 4 feet above the base flood elevation, 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:
(a) Fill may not be placed in the area of special flood hazard except in accordance with the provisions of § 8-38(f)
(b) Fill may not be placed in tidal or non-tidal wetlands without the required state and federal permits;
(c) Fill must consist of soil and rock materials only. Dredged material may be used as fill only upon certification of suitability by a registered professional geotechnical engineer. Landfills, rubble fills, dumps, and sanitary fills are not permitted in the floodplain;
(d) Fill used to support structures must comply with ASTM Standard D-698, as amended and its suitability to support structures certified by a SC Registered Professional Engineer;
(e) Fill slopes shall be no greater than 2 horizontal to 1 vertical. Flatter slopes may be required where velocities may result in erosion; and
(f) No encroachment/development, including fill, shall be permitted within the area of special flood hazard unless certification with supporting technical data, prepared by a SC registered engineer, is provided to demonstrate that the encroachment will not result in adverse impact to the floodplain. Adverse impact includes, but is not limited to, any increase in base flood elevation, floodway elevation and floodway width.
The floodplain administrator will evaluate each encroachment/development and determine which of the following options will be required.
(1) Option 1: Compensatory storage may be allowed for all storage lost or displaced in a regulatory floodplain. Hydraulically equivalent compensatory storage requirements for fill or structures in a riverine regulatory floodplain shall be at least equal to 1.5 times the volume of regulatory floodplain storage lost or displaced. Such compensation areas shall be designed to drain freely and openly to the channel and shall be located opposite or adjacent to fill areas. A recorded deed or plat restriction is required to prohibit any modification to the compensation area. The regulatory floodplain storage volume lost below the existing ten-year frequency flood elevation must be replaced below the proposed ten-year frequency flood elevation. The regulatory floodplain storage volume lost above the ten-year existing frequency flood elevation must be replaced above the proposed ten-year frequency elevation; and/or
(2) Option 2: A detailed hydrologic and hydraulic analyses performed in accordance with standard engineering practice that meets the requirements of the NFIP. The analyses may incorporate compensatory storage at hydraulically equivalent sites within the proposed project area as part of the required demonstration.
If the encroachment results in adverse impact to the floodplain, the applicant shall submit to DHS-FEMA a Conditional Letter of Map Revision (CLOMR) or other appropriate map change application. Within 60 calendar days of completion of construction activities, the applicant shall apply to DHS-FEMA for a Letter of Map Revision (LOMR). The floodplain development permit will not be issued until DHS-FEMA has issued the CLOMR. The applicant is responsible for all technical submissions and fees required to obtain the CLOMR/LOMR (See § 8-29(b)(9)).
(Ord. 4085, § 2, passed 2-20-2007; Ord. 4631, § 2, passed 6-17-2014; Ord. 5031, passed 11-6-2018; Ord. 5276, passed 4-6-2021)