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A. Permitted Uses: Permitted uses shall be those uses of land or structures listed as permitted uses in the underlying zoning use district(s). All permitted uses shall comply with the standards for flood fringe district "permitted uses" listed in subsection B of this section and subsection E, "Standards For All Flood Fringe Uses", of this section.
B. Standards For Flood Fringe Permitted Uses:
1. All structures, including accessory structures, must be elevated on fill so that the lowest floor including basement floor is at or above the regulatory flood protection elevation. The finished fill elevation for structures shall be no lower than one foot (1') below the regulatory flood protection elevation and the fill shall extend at such elevation at least fifteen feet (15') beyond the outside limits of the structure erected thereon.
2. As an alternative to elevation on fill, accessory structures that constitute a minimal investment and that do not exceed five hundred (500) square feet at its largest projection may be internally floodproofed in accordance with subsection 11-12-4D5c of this chapter.
3. The cumulative placement of fill where at any one time in excess of one thousand (1,000) cubic yards of fill is located on the parcel shall be allowable only as a conditional use, unless said fill is specifically intended to elevate a structure in accordance with subsection B1 of this section.
4. The storage of any materials or equipment shall be elevated on fill to the regulatory flood protection elevation.
5. The provisions of subsection E of this section shall apply.
C. Conditional Uses: Any structure that is not elevated on fill or floodproofed in accordance with subsections B1 through B2 of this section or any use of land that does not comply with the standards in subsections B3 through B4 of this section shall only be allowable as a conditional use. An application for a conditional use shall be subject to the standards and criteria and evaluation procedures specified in subsections D and E of this section and subsection 11-12-10D of this chapter.
D. Standards For Flood Fringe Conditional Uses:
1. Alternative Methods: Alternative elevation methods other than the use of fill may be utilized to elevate a structure's lowest floor above the regulatory flood protection elevation. These alternative methods may include the use of stilts, pilings, parallel walls, etc., or above grade, enclosed areas such as crawl spaces or tuck under garages. The base or floor of an enclosed area shall be considered above grade and not a structure's basement or lowest floor if: a) the enclosed area is above grade on at least one side of the structure; b) it is designed to internally flood and is constructed with flood resistant materials; and c) it is used solely for parking of vehicles, building access or storage. The above noted alternative elevation methods are subject to the following additional standards:
a. Design And Certification: The structure's design and as built condition must be certified by a registered professional engineer or architect as being in compliance with the general design standards of the state building code and, specifically, that all electrical, heating, ventilation, plumbing and air conditioning equipment and other service facilities must be at or above the regulatory flood protection elevation or be designed to prevent floodwater from entering or accumulating within these components during times of flooding.
b. Specific Standards For Above Grade, Enclosed Areas: Above grade, fully enclosed areas such as crawl spaces or tuck under garages must be designed to internally flood and the design plans must stipulate:
(1) A minimum area of openings in the walls where internal flooding is to be used as a floodproofing technique. There shall be a minimum of two (2) openings on at least two (2) sides of the structure and the bottom of all openings shall be no higher than one foot (1') above grade. The automatic openings shall have a minimum net area of not less than one square inch for every square foot of enclosed area subject to flooding unless a registered professional engineer or architect certifies that a smaller net area would suffice. The automatic openings may be equipped with screens, louvers, valves, or other coverings or devices provided that they permit the automatic entry and exit of floodwaters without any form of human intervention; and
(2) That the enclosed area will be designed of flood resistant materials in accordance with the FP-3 or FP-4 classifications in the state building code and shall be used solely for building access, parking of vehicles or storage.
2. Basements: Basements, as defined by section 11-1-3 of this title, shall be subject to the following:
a. Residential basement construction shall not be allowed below the regulatory flood protection elevation.
b. Nonresidential basements may be allowed below the regulatory flood protection elevation provided the basement is structurally dry floodproofed in accordance with subsection D3 of this section.
3. Floodproofing Structures Below Regulatory Flood Protection Elevation: All areas of nonresidential structures including basements to be placed below the regulatory flood protection elevation shall be floodproofed in accordance with the structurally dry floodproofing classifications in the state building code. Structurally dry floodproofing must meet the FP-1 or FP-2 floodproofing classification in the state building code and this shall require making the structure watertight with the walls substantially impermeable to the passage of water and with structural components having the capability of resisting hydrostatic and hydrodynamic loads and the effects of buoyancy. Structures floodproofed to the FP-3 or FP-4 classification shall not be permitted.
4. Erosion/Sedimentation Control Plan: When at any one time more than one thousand (1,000) cubic yards of fill or other similar material is located on a parcel for such activities as on site storage, landscaping, sand and gravel operations, landfills, roads, dredge spoil disposal or construction of flood control works, an erosion/sedimentation control plan must be submitted unless the city is enforcing a state approved shore land management ordinance. In the absence of a state approved shore land ordinance, the plan must clearly specify methods to be used to stabilize the fill on site for a flood event at a minimum of the 100-year or regional flood event. The plan must be prepared and certified by a registered professional engineer or other qualified individual acceptable to the city council. The plan may incorporate alternative procedures for removal of the material from the floodplain if adequate flood warning time exists.
5. Storage Of Materials And Equipment:
a. The storage or processing of materials that are, in time of flooding, flammable, explosive, or potentially injurious to human, animal, or plant life is prohibited.
b. Storage of other materials or equipment may be allowed if readily removable from the area within the time available after a flood warning and in accordance with a plan approved by the city council.
6. Other Provisions That Apply: The provisions of subsection E of this section shall also apply.
E. Standards For All Flood Fringe Uses:
1. All new principal structures must have vehicular access at or above an elevation not more than two feet (2') below the regulatory flood protection elevation. If a variance to this requirement is granted, the board of zoning appeals must specify limitations on the period of use or occupancy of the structure for times of flooding and only after determining that adequate flood warning time and local flood emergency response procedures exist.
2. Commercial uses: Accessory land uses, such as yards, railroad tracks, and parking lots may be at elevations lower than the regulatory flood protection elevation. However, a permit for such facilities to be used by the employees or the general public shall not be granted in the absence of a flood warning system that provides adequate time for evacuation if the area would be inundated to a depth and velocity such that when multiplying the depth (in feet) times velocity (in feet per second) the product number exceeds four (4) upon occurrence of the regional flood.
3. Manufacturing and industrial uses: Measures shall be taken to minimize interference with normal plant operations especially along streams having protracted flood durations. Certain accessory land uses such as yards and parking lots may be at lower elevations subject to requirements set out in subsection E2 of this section. In considering permit applications, due consideration shall be given to needs of an industry whose business requires that it be located in floodplain areas.
4. Fill shall be properly compacted and the slopes shall be properly protected by the use of riprap, vegetative cover or other acceptable method. The federal emergency management agency (FEMA) has established criteria for removing the special flood hazard area designation for certain structures properly elevated on fill above the 100-year flood elevation; FEMA's requirements incorporate specific fill compaction and side slope protection standards for multi-structure or multi-lot developments. These standards should be investigated prior to the initiation of site preparation if a change of special flood hazard area designation will be requested.
5. Floodplain developments shall not adversely affect the hydraulic capacity of the channel and adjoining floodplain of any tributary watercourse or drainage system where a floodway or other encroachment limit has not been specified on the official zoning map.
6. Standards for recreational vehicles are contained in subsection 11-12-9C of this chapter.
7. All manufactured homes must be securely anchored to an adequately anchored foundation system that resists flotation, collapse and lateral movement. Methods of anchoring may include, but are not to be limited to, use of over the top or frame ties to ground anchors. This requirement is in addition to applicable state or local anchoring requirements for resisting wind forces. (Ord. 872, 2-3-2010)