Shallow flooding zones appear in FIRMs, as AO Zones with depth designations. The base flood depths in these zones range from one foot (1') to three feet (3') where a clearly defined channel does not exist, or where the path of flooding is unpredictable and where velocity flow may be evident. Such flooding is usually characterized as sheet flow. In those areas, the following provisions apply:
A. New construction and substantial improvements of residential structures within AO Zones shall have the lowest floor (including basement) elevated above the adjacent grade of the building site, to or above the depth number specified on the FIRM (at least 2 feet if no depth number as specified).
B. New construction and substantial improvements of nonresidential structures within AO Zones shall either:
1. Have the lowest floor (including basement) elevated above the highest adjacent grade of the building site, to or above the depth number specified on the FIRM (at least 2 feet if no depth number is specified); or
2. Together with attendant utility and sanitary facilities, be completely floodproofed to or above that level so that any space below that level is watertight with walls substantially impermeable to the passage of water and with structural components having the capability or resisting hydrostatic and hydrodynamic loads and effects of buoyancy. If this method is used, compliance shall be certified by a registered professional engineer or architect as in subsection 11-1-7B3 of this chapter.
C. Require adequate drainage paths around structures on slopes to guide floodwaters around and away from proposed structures. (Ord. 87-7, 6-15-1987)
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