Whenever any portion of a floodplain is authorized for use, the volume of space which will be occupied by the authorized fill or structure below the base flood or 100-year frequency flood elevation shall be compensated for and balanced by a hydraulically equivalent volume of excavation taken from below the base flood or 100-year frequency flood elevation. The following standards apply within the regulatory floodplain.
(A) Hydraulically equivalent compensatory storage volume will be required for development in a riverine or non-riverine regulatory floodplain and shall be at least one and one-fourth times the regulatory floodplain flood storage volume displaced. The storage volume displaced below the existing ten-year frequency flood elevation must be replaced below the proposed ten-year frequency flood elevation. The storage volume displaced above the ten-year existing frequency flood elevation must be replaced above the proposed ten-year frequency flood elevation.
(B) Compensatory storage areas shall be designed to drain freely and openly to the watercourse, and in the case of streams and watercourses, the excavation shall be located opposite or adjacent to the areas so filled or occupied.
(C) A recorded covenant running with the land is required to maintain the compensatory storage volume in areas modified to provide compensatory storage volume.
(D) Existing depressional storage shall meet the requirements of § 164.021(F).
(Ord. 10-164, passed 6-17-2010)