In all areas of special flood hazard, the following standards are required:
1. All new construction and substantial improvements shall be anchored to prevent flotation, collapse or lateral movement of the structure.
2. All manufactured homes must likewise 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 (reference FEMA's "Manufactured Home Installation In Flood Hazard Areas" guidebook for additional techniques).
B. Construction Materials And Methods:
1. All new construction and substantial improvements shall be constructed with materials and utility equipment resistant to flood damage.
2. All new construction and substantial improvements shall be constructed using methods and practices that minimize flood damage.
3. Electrical, heating, ventilation, plumbing, and air conditioning equipment and other service facilities shall be designed and/or otherwise elevated or located so as to prevent water from entering or accumulating within the component during conditions of flooding.
1. All new and replacement water supply systems shall be designed to minimize or eliminate infiltration of floodwaters into the system;
2. New and replacement sanitary sewage systems shall be designed to minimize or eliminate infiltration of floodwaters into the systems and discharge from the systems into floodwaters; and
3. On site waste disposal systems shall be located to avoid impairment to them or contamination from them during flooding consistent with the administrative rules of the Oregon department of environmental quality.
D. Subdivision Applications: Applications shall be consistent with the need to minimize flood damage; shall have public utilities and facilities such as sewer, gas, electrical, and water systems located and constructed to minimize flood damage; and shall have adequate drainage provided to reduce exposure to flood damage; and, where base flood elevation data has not been provided or is not available from another authoritative source, it shall be generated for subdivision proposals and other proposed developments which contain at least fifty (50) lots or five (5) acres (whichever is less).
E. Review Of Building Permits: Where elevation data is not available from the flood insurance study, FIRM, or some other authoritative source, applications for building permits shall be reviewed to assure that proposed construction will be reasonably safe from flooding. The test of reasonableness is a local judgment and includes use of historical data, high water marks, photographs of past flooding, etc., where available. Failure to elevate at least two feet (2') above grade in these zones may result in higher insurance rates.
F. Residential Construction: New construction and substantial improvement of any residential structure shall have the lowest floor, including basement, elevated a minimum of one foot (1') above the base flood elevation. Fully enclosed areas below the lowest floor that are subject to flooding are prohibited, or 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 must either be certified by a registered professional engineer or architect or must meet or exceed the following minimum criteria:
1. A minimum of two (2) openings having a total net area of 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 (1') above grade.
3. Openings may be equipped with screens, louvers, or other covering or devices; provided, that they permit the automatic entry and exit of floodwaters.
G. Nonresidential Construction: New construction and substantial improvement of any commercial, industrial or other nonresidential structure shall either have the lowest floor, including basement, elevated a minimum of one foot (1') above the base flood elevation; or, together with attendant utility and sanitary facilities, shall:
1. Be floodproofed so that below the base flood level the structure is watertight with walls substantially impermeable to the passage of water.
2. Have structural components capable of resisting hydrostatic and hydrodynamic loads and effects of buoyancy.
3. Be certified by a registered professional engineer or architect that the design and methods of construction are in accordance with accepted standards of practice for meeting provisions of this subsection based on their development and/or review of the structural design, specifications and plans.
4. Nonresidential structures that are elevated, not floodproofed, must meet the same standards for space below the lowest floor as described in subsection F of this section.
5. Applicants floodproofing nonresidential buildings shall be notified that flood insurance premiums will be based on rates that are one foot (1') below the floodproofed level (e.g., a building constructed to the base flood level will be rated as 1 foot below that level).
H. Manufactured Dwellings: For manufactured dwellings to be placed or substantially improved on sites:
1. The ground area reserved for the placement of a manufactured dwelling shall be a minimum of twelve inches (12") above BFE unless the foundation walls are designed to automatically equalize hydrostatic forces on exterior walls by allowing for the entry and exit of floodwaters. Designs for meeting this requirement must be either certified by a registered professional engineer or architect or must meet or exceed the following minimum criteria:
a. A minimum of two (2) openings having a total net area of not less than one square inch for every square foot of enclosed area subject to flooding shall be provided;
b. The bottom of all openings shall be no higher than one foot (1') above grade; and
c. Openings may be equipped with screens, louvers, or other coverings or devices provided that they permit the automatic entry and exit of floodwaters;
2. The bottom of the longitude chassis frame beam in A zones, and the bottom of the lowest horizontal structural member supporting the dwelling in V zones shall be a minimum of twelve inches (12") above BFE;
3. The manufactured dwelling shall be anchored to prevent flotation, collapse and lateral movement during the base flood. Anchoring methods may include, but are not limited to, use of over the top or frame ties to ground anchors (reference FEMA's "Manufactured Dwelling Installation In Flood Hazard Areas" guidebook for additional techniques); and
4. Electrical crossover connections shall be a minimum of twelve inches (12") above BFE.
I. Recreational Vehicles: Recreational vehicles placed on sites are required to either:
1. Be on the site for fewer than one hundred eighty (180) consecutive days;
2. Be fully licensed and ready for highway use, on its wheels or jacking system, is attached to the site only by quick disconnect type utilities and security devices, and has no permanently attached additions; or
3. Meet the requirements of subsection H of this section and the elevation and anchoring requirements for manufactured dwellings.
J. Building Setbacks: Within the flood hazard zone, a twenty five foot (25') building setback from the ordinary high water line of all rivers and streams shall be maintained. Within this building setback, riparian vegetation shall be maintained to the maximum extent feasible. The intent of this provision is the stabilization of the river and stream banks by maintaining the existing vegetation. Requests for a variance to this standard must be accompanied with a plan to mitigate the adverse impacts of construction on this sensitive vegetation. This plan may include the replanting of the area with vegetation such as willows or other riparian vegetation to restore the area after construction is finished.
K. Before Regulatory Floodway: In areas where a regulatory floodway has not been designated, no new construction, substantial improvements, or other development (including fill) shall be permitted within zones A1-30 and AE on the community's FIRM, unless it is demonstrated that the cumulative effect of the proposed development, when combined with all other existing and anticipated development, will not increase the water surface elevation of the base flood more than one foot (1') at any point within the community. (Ord. 664, 11-3-2010)