A. General Standards. In all areas of flood hazards the following standards are required:
a. All new construction and substantial improvements shall be anchored to prevent flotation, collapse or lateral movement of the structure;
b. 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).
2. Construction Materials and Methods.
a. All new construction and substantial improvements shall be constructed with materials and utility equipment resistant to flood damage.
b. All new construction and substantial improvements shall be constructed using methods and practices that minimize flood damage.
c. 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 components during conditions of flooding.
a. All new and replacement water supply systems shall be designed to minimize or eliminate infiltration of flood waters into the system;
b. New and replacement sanitary sewage systems shall be designed to minimize or eliminate infiltration of flood waters into the systems and discharge from the systems into flood waters; and
c. On-site waste disposal systems shall be located to avoid impairment to them or contamination during flooding.
4. Subdivision Proposals.
a. All subdivision proposals shall be consistent with the need to minimize flood damage;
b. All subdivision proposals shall have public utilities and facilities such as sewer, gas, electrical, and water systems located and constructed to minimize flood damage;
c. All subdivision proposals shall have adequate drainage provided to reduce exposure to flood damage; and
d. 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 development which contain at least fifty (50) lots or five (5) acres, whichever is less.
5. Review of Building Permit.
a. Where elevation data is not available, either through the Flood Insurance Study or from another authoritative source (Section 15.10.070.C) 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 the lowest floor at least two (2) feet above grade in these zones may result in higher insurance rates.
b. To determine the flood base elevation, the applicant’s Oregon registered engineer or land surveyor shall investigate all available sources of information, such as historic flooding profiles, high water marks, photographs of past flooding, soil characteristics, or any other feasible methods. A report shall be submitted to the City by the applicant, setting forth said elevation and citing the evidence upon which the estimate is made. Said report may be accepted or rejected by the City. The Oregon registered engineer or surveyor shall place a permanent elevation marker on the property.
B. Specific Standards. In all areas of special flood hazards where base flood elevation data has been provided as set forth in Section 15.10.060.B, “Basis for Establishing the Areas of Special Flood Hazard”, or Section 15.10.070.C.2, “Use of Other Base Flood Data, the following provisions are required:
1. Residential Construction.
a. New construction and substantial improvement of any residential structure shall have the lowest floor, including basement, elevated to at least two (2) feet or above base flood elevation. Prior to the issuance of a certificate of occupancy by the City, the property owner shall furnish certification by a registered engineer or surveyor of the actual elevation of the lowest habitable floor, including a basement.
b. Fully enclosed areas below the lowest floor that are subject to flooding are prohibited, or shall be designed to automatically equalize hydrostatic flood sources on exterior walls by allowing for entry and exit of flood-waters. 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:
(i) A minimum of two openings having a total net area of not less than one (1) square inch for every square foot of enclosed area subject to flooding.
(ii) The bottom of all openings shall be no higher than one (1) foot above grade.
(iii) Openings may be equipped with screens, louvers, or other coverings or devices provided that they permit the automatic entry and exit of flood-waters.
2. Nonresidential Construction. New construction and substantial improvement of any commercial, industrial or other nonresidential structure shall either have the lowest floor, including basement, elevated to the level of the base flood elevation; or together with attendant utility and sanitary facilities; shall:
a. Be flood-proofed so that below the base flood level the structure is watertight with walls substantially impermeable to the passage of water;
b. Have structural components capable of resisting hydrostatic and hydrodynamic loads and effects of buoyancy; and
c. Be certified by an Oregon registered professional engineer or architect that the designs and methods of construction are in accordance with accepted standards of practice for meeting the provisions of this subsection based on their development review of the structural design, specifications and plans. Such certifications shall be provided to the official as set forth in Section 15.10.070.C.3.b.
d. Nonresidential structures that are elevated, not flood-proofed, must meet the same standards for space below the lowest floor as described in 15.10.080.B.1.b.
e. Applicants flood-proofing nonresidential buildings shall be notified that flood insurance premiums will be based on rates that are one (1) foot below the flood proofed level (e.g., a building constructed to the base flood level will be rated as one (1) foot below that level).
3. Manufactured Homes. All manufactured homes to be placed or substantially improved within Zones A1-30, AH, and AE shall be elevated on a permanent foundation such that the lowest floor of the manufactured home is at least two (2) feet above the base flood elevation and be securely anchored to an adequately anchored foundation system in accordance with the provisions of Section 15.10.080.A.1.
4. Recreational vehicles placed on sites are required to either:
a. Be on the site for fewer than 180 consecutive days,
b. 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
c. Meet the requirements of Section 15.10.080 the elevation and anchoring requirements for manufactured homes.
5. Critical Facility. Construction of new critical facilities shall be, to the extent possible, located outside the limits of the Special Flood Hazard Area (SFHA) (100-year floodplain). Construction of new critical facilities shall be permissible within the SFHA if no feasible alternative site is available. Critical facilities constructed within the SFHA shall have the lowest floor elevated three feet above BFE or to the height of the 500-year flood, whichever is higher. Access to and from the critical facility should also be protected to the height utilized above. Flood proofing and sealing Measures must be taken to ensure that toxic substances will not be displaced by or released into floodwaters. Access routes elevated to or above the level of the base flood elevation shall be provided to all critical facilities to the extent possible.
6. Below-grade Crawl Spaces. Below-grade crawl spaces area allowed provided they conform to the guidelines in FEMA Technical Bulletin 11-01, Crawlspace Construction for Buildings Located in Special Flood Hazard Areas.
C. Flood-ways. Located within areas of special flood hazard established in Section 15.10.060.B are areas designated as flood-ways. Since the flood-way is an extremely hazardous area due to the velocity of flood waters which carry debris, potential projectiles, and erosion potential, the following provisions apply:
1. Prohibit encroachments, including fill, new construction, substantial improvements, and other development unless certification by a registered professional engineer or architect is provided demonstrating that encroachments shall not result in any increase in flood levels during the occurrence of the base flood discharge.
2. If Section 15.10.080.C.1 above is satisfied, all new construction, and substantial improvements shall comply with all applicable flood hazard reduction provisions of Section 15.10.080, “Provisions for Flood Hazard Protection”. (Ord. 3046, amended, 03/15/2011; Ord. 2925, amended, 04/18/2006)