A. General Standards: In all areas of special flood hazard, the following standards are required:
1. Anchoring:
a. All new construction and substantial improvements shall be anchored to prevent flotation, collapse, or lateral movement of the structure. (Ord. 1987-3, 4-8-1987)
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. For more detailed information, refer to guidebook FEMA-85, "Manufactured Home Installation In Flood Hazard Areas". (Ord. 2009-4, 7-2-2009, eff. 7-7-2009)
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. (Ord. 1987-3, 4-8-1987)
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. Locating such equipment below the flood protection elevation may cause annual flood insurance premiums to be increased. (Ord. 2009-4, 7-2-2009, eff. 7-7-2009)
3. Utilities:
a. All new and replacement water supply systems shall be designed to minimize or eliminate infiltration of floodwaters into the system;
b. 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
c. On site waste disposal systems shall be located to avoid impairment to them or contamination from them during flooding. (Ord. 1987-3, 4-8-1987)
d. Water wells, if permitted by the city, shall be located on high ground that is not in the floodway. (Ord. 2009-4, 7-2-2009, eff. 7-7-2009)
4. Subdivision Proposals:
a. All subdivision proposals shall be consistent with the need to minimize flood damage; (Ord. 1987-3, 4-8-1987)
b. All subdivision proposals shall have public utilities and facilities such as sewer, gas, electrical, and water systems located and constructed to minimize or eliminate flood damage; (Ord. 2009-4, 7-2-2009, eff. 7-7-2009)
c. All subdivision proposals shall have adequate drainage provided to reduce exposure to flood damage; and (Ord. 1987-3, 4-8-1987)
d. Where flood protection 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). (Ord. 1987-3, 4-8-1987; amd. Ord. 2009-4, 7-2-2009, eff. 7-7-2009)
5. Review Of Building Permits: Where flood protection elevations or other current engineering data are not available either through the flood insurance study, FIRM, or from another authoritative source (subsection 12-1-7B2 of this chapter), the floodplain administrator shall obtain, review, and reasonably utilize scientific methods 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 the highest adjacent grade in these zones may result in higher insurance rates. (Ord. 2009-4, 7-2-2009, eff. 7-7-2009)
1. Residential Construction:
a. Where flood protection data is available, any structure or manufactured home shall have the lowest floor, including basement, elevated to or above the flood protection elevation.
b. Fully enclosed areas below the lowest floor that are subject to flooding are prohibited, or shall be designed to equalize hydrostatic flood forces on exterior walls by allowing for the automatic 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 coverings or devices provided that they permit the automatic entry and exit of floodwaters. Standard foundation vents as required by the international building code do not meet this standard.
(4) Below grade, crawl spaces are prohibited at sites where the velocity of floodwaters exceeds five feet (5') per second.
(5) All building utility systems within the crawl space shall be elevated above flood protection elevation or be designed so that floodwaters cannot enter or accumulate within the system component during a flood.
(6) The interior of a crawl space below the flood protection elevation must not be more than two feet (2') below the lowest adjacent exterior grade (LAG) and the height of the below grade crawl space, measured from the interior grade of the crawl space to the top of the crawl space foundation must not exceed four feet (4') at any point.
(7) Below grade, crawl spaces constructed in accordance with the requirements listed in this subsection shall not be considered basements. However, applicants who construct buildings that have below grade crawl spaces are hereby advised that such buildings will have higher flood insurance premiums than buildings that have crawl spaces with interior elevations at or above the lowest adjacent grade.
(8) Below grade unfinished or flood resistant enclosures shall only be used for parking of vehicles, limited storage of maintenance equipment, or building access.
(9) Otherwise follow the guidelines of the latest version of FEMA TB 11-01 construction for buildings located in special flood hazard areas: national flood insurance program interim guidance for crawl space construction. (Ord. 2009-4, 7-2-2009, eff. 7-7-2009)
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 flood protection elevation; or, together with attendant utility and sanitary facilities, shall: (Ord. 1987-3, 4-8-1987; amd. Ord. 2009-4, 7-2-2009, eff. 7-7-2009)
a. Be floodproofed 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 effect of buoyancy;
c. 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. Such certifications shall be provided to the official as set forth in subsection 12-1-7B3b of this chapter.
d. Nonresidential structures that are elevated, not floodproofed, must meet the same standards for space below the lowest floor as described in subsection 12-1-9B1b of this chapter. (Ord. 1987-3, 4-8-1987)
e. 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). Floodproofing the building an additional foot will reduce insurance premiums significantly.
f. Otherwise follow the guidelines of the latest version of FEMA TB 11-01 crawl space construction for buildings located in special flood hazard areas: national flood insurance program interim guidance for crawl space construction.
3. Manufactured Homes: All or varied placement of manufactured homes in the floodplain shall be elevated on a permanent foundation such that the lowest floor of the manufactured home is at or above the flood protection elevation and be securely anchored to an adequately anchored foundation system in accordance with the provisions of subsection 12-1-9A1b of this chapter to resist flotation, collapse and lateral movement.
4. Recreational Vehicles: All recreational vehicles placed on sites within the city shall either:
a. Be on the site for fewer than one hundred eighty (180) consecutive days; or
b. Be fully licensed and ready for highway use, on wheels or jacking system, attached to the site only by quick disconnect type utilities and security devices, and have no permanently attached additions; or
c. Meet the permit requirements of this chapter, and the elevation and anchoring requirements for "manufactured homes" as defined in this chapter.
5. AE And A1-30 Zones With Flood Protection Elevations But No Floodways: In areas with flood protection elevations (but 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.
6. Building Standards For Areas Of Shallow Flooding (AO Zones): Areas of special flood hazard may include designated AO shallow flooding areas. These areas have base flood depths of one to three feet (3') aboveground, with no clearly defined channel. Such flooding is usually characterized as sheet flow. In these areas the following provisions apply:
a. All new construction and substantial improvements of residential and nonresidential structures shall have the lowest floor, including basement, elevated above the highest adjacent grade at least as high as depth number specified in feet on the community's flood insurance rate map (FIRM) or at least two feet (2') if no depth number is specified. Openings sufficient to facilitate the unimpeded movements of floodwaters shall be provided in accordance with standards of subsection B1 of this section;
b. New construction or the substantial improvement of a nonresidential structure may be floodproofed in lieu of elevation. The structure, together with attendant utility and sanitary facilities, must be designed to be watertight to the specified flood protection elevation, with walls substantially impermeable to the passage of water, and structural components having the capability of resisting hydrostatic and hydrodynamic loads and the effect of buoyancy. A registered professional engineer or architect shall certify that the design and methods of construction are in accordance with accepted standards of practice; and
c. Drainage paths shall be provided to guide floodwater around and away from a proposed structure.
7. 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 (3') above FPE 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. Floodproofing 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 flood protection elevation shall be provided to all critical facilities to the extent possible. (Ord. 2009-4, 7-2-2009, eff. 7-7-2009)
C. Floodways: Located within areas of special flood hazard established in subsection 12-1-6B of this chapter are areas designated as floodways. Since the floodway is an extremely hazardous area due to the velocity of floodwaters 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 subsection C1 of this section is satisfied, all new construction and substantial improvements shall comply with all applicable flood hazard reduction provisions of this section. (Ord. 1987-3, 4-8-1987)
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