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A. All new structures and substantial improvements shall have the lowest floor, including basement, elevated to or above the FPE.

B. New construction and substantial improvement of any residential structure in an unnumbered A zone for which a BFE is not available and cannot be reasonably obtained shall be reasonably safe from flooding, but in all cases the lowest floor shall be at least two feet above the highest adjacent grade.

C. The structure shall be aligned parallel with the direction of flood flows where practicable.

D. The structure shall be anchored to prevent flotation, collapse, or lateral movement of the structure resulting from hydrodynamic and hydrostatic loads including the effects of buoyancy.

E. All manufactured homes shall be anchored to prevent flotation, collapse, or lateral movement, and shall be installed using methods and practices that minimize flood damage. Anchoring methods may include, but are not limited to, use of over-the-top or frame ties to ground anchors.

F. All materials below the FPE shall be resistant to flood damage and firmly anchored to prevent flotation. Materials harmful to aquatic wildlife, such as creosote, are prohibited below the FPE.

G. All new construction and substantial improvements shall be constructed using methods and practices that minimize flood damage.

H. Electrical, heating, ventilation, duct work, plumbing, and air-conditioning equipment and other service facilities shall be elevated to or above the FPE. Water, sewage, electrical, and other utility lines (excluding storm drainage facilities) below the FPE shall be constructed so as to minimize water from entering or accumulating within them during conditions of flooding.

I. Fully enclosed areas below the lowest floor that are subject to flooding shall be used only for parking, limited storage, or building access and shall be designed to automatically equalize hydrostatic flood forces on exterior walls by allowing for the entry and exit of floodwaters. Designs for meeting this requirement shall either be certified by a registered professional engineer or licensed architect in the state of Washington and/or meet or exceed the following minimum criteria:

1. A minimum of two openings having a total net area not less than one square inch for every square foot of enclosed area subject to flooding shall be provided.

2. The bottom of all openings shall be no higher than one foot above grade.

3. Openings may be equipped with screens, louvers, or other coverings or devices; provided, that they permit the automatic entry and exit of floodwaters.

4. A garage attached to a residential structure, constructed with the garage floor slab below the BFE, must be designed to allow for the automatic entry and exit of floodwaters. (Ord. 6761 § 1 (Exh. A), 2020.)