If detention storage is provided within a floodplain, only the net increase in storage volume above that which naturally existed on the floodplain shall be credited to the development. No credit will be granted for volumes below the elevation of the base flood at that location unless compensatory storage is also provided. Where encroachments in the existing floodplain fill the valley storage areas, an equal amount of detention volume shall be provided.
(1999 Code, § 34-5-57)