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In addition to the substantive requirements of SPMC 15.18.130, the following requirements shall apply to floodplains:

A. To the extent possible consistent with the development objective, all improvements shall be located on the nonfloodplain portion of the site, if any, or on the highest ground on the site, as far as possible from the flood source.

B. New and substantially improved residential structures shall have the lowest floor, including basement, elevated one foot or more above the 100-year flood elevation. In addition, new and substantially improved manufactured homes shall be securely anchored to resist flotation, collapse, and lateral movement.

C. New and substantially improved nonresidential structures shall either:

1. Have the lowest floor, including basement, elevated one foot or more above the 100-year flood elevation; or

2. Together with utilities and sanitary facilities, be certified by a registered professional engineer or architect as being floodproofed, so that below one foot or more above the 100-year flood level the structure is watertight and capable of resisting hydrostatic and hydrodynamic loads and buoyancy.

D. Fully enclosed areas below the lowest habitable floor that are not floodproofed shall be certified by a registered professional engineer or architect as designed to resist hydrostatic flood forces.

E. New and replacement water supply systems shall be designed to minimize infiltration of floodwaters into the systems.

F. New and replacement sanitary sewage systems and on-site septic systems shall be designed to minimize infiltration of floodwaters into and discharges from the system.

G. All new construction and substantial improvements, including electrical, heating, ventilation, plumbing, and air-conditioning equipment, shall be constructed using flood-resistant materials and methods.

H. Alteration of natural watercourses shall be avoided if feasible. If unavoidable, the director shall notify adjacent communities, the Department of Ecology, and FEMA prior to alteration. Any stream-bank stabilization shall use soft armoring (bioengineering). Removal of vegetation and woody debris shall be minimized. The alteration shall not block side channels or diminish flood-carrying capacity.

I. Development in floodplains shall be designed to minimize impacts to such ecological functions as wildlife movement and aquifer recharge. Fill and grading may be placed in areas which in the event of a 100-year flood would be covered with relatively static floodwaters but not in a manner which would block side channels or inhibit channel migration.

J. Recreational vehicles shall either be on the site for fewer than 180 consecutive days or be fully licensed and ready for highway use. [Ord. 492 § 3 (Exh. B § 153), 2007.]