30.65.290 Shallow flooding areas: standards.
Areas of shallow flooding appear on FIRMs as AO zones with depth designations. The base flood depths in these zones range from one to three feet above ground 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 addition to other applicable provisions in this code, the following provisions apply in AO zones:
(1) New construction and substantial improvements of residential structures and mobile homes within AO zones shall have the lowest floor (including basement and mechanical equipment) elevated above the highest adjacent grade to the structure, one foot or more above the depth number specified in feet on the applicable FIRM (at least two feet above the highest adjacent grade to the structure if no depth number is specified).
(2) New construction and substantial improvements of nonresidential structures within AO zones shall either:
(a) Have the lowest floor (including basement) elevated above the highest adjacent grade of the building site, one foot or more above the depth number specified on the FIRM (at least two feet if no depth number is specified); or
(b) Together with attendant utility and sanitary facilities, be completely floodproofed to a level above the highest adjacent grade that equals or exceeds the depth number specified on the FIRM (at least two feet if no depth number is specified) plus one foot. Any space below that level must be watertight with walls substantially impermeable to the passage of water and have the capability of resisting hydrostatic and hydrodynamic loads and effects of buoyancy. Compliance shall be certified by a registered professional engineer or architect under SCC 30.65.130.
(3) Adequate drainage paths around structures on slopes are required to guide floodwaters around and away from proposed structures.
(4) Recreational vehicles placed on sites within AO zones on the applicable FIRM shall:
(b) Be fully licensed and ready for highway use, on its wheels or jacking system, attached to the site only by quick disconnect type utilities and security devices, and have no permanently attached additions. (Added by Ord. 20-076, Nov. 4, 2020, Eff date Nov. 27, 2020).