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The provisions of this chapter shall apply to all lands and uses which have significant flood hazards. The Flood Insurance Rate Maps (FIRM) for Carroll County and Incorporated Areas, City of Carroll, Panels 19027C0134C, 0142C, 0151C, 0153C, 0161C, 0162C, dated September 15, 2017, which were prepared as part of the Carroll County Flood Insurance Study, shall be used to identify such flood hazard areas and all areas shown thereon to be within the boundaries of the 100-year flood shall be considered as having significant flood hazards. Where uncertainty exists with respect to the precise location of the 100-year flood boundary, the location shall be determined on the basis of the 100-year flood elevation at the particular site in question. The Flood Insurance Study is hereby adopted by reference and is made a part of this chapter for the purpose of administering flood plain management regulations.
(Ord. 1706 - Sep. 17 Supp.)
It is not intended by this chapter to repeal, abrogate, or impair any existing easements, covenants, or deed restrictions. However, where this chapter imposes greater restrictions, the provision of this chapter shall prevail. Any ordinances inconsistent with this chapter are hereby repealed to the extent of the inconsistency only.
The standards required by this chapter are considered reasonable for regulatory purposes. This chapter does not imply that areas outside the designated areas of significant flood hazard will be free from flooding or flood damages. This chapter shall not create liability on the part of the City or any officer or employee thereof for any flood damages that result from reliance on this chapter or any administrative decision lawfully made thereunder.
All uses must be consistent with the need to minimize flood damage and shall meet the following applicable performance standards. Where 100-year flood data has not been provided in the Flood Insurance Study, the Department of Natural Resources shall be contacted to determine: (i) whether the land involved is either wholly or partly within the floodway or floodway fringe; and (ii) the 100-year flood level. The applicant will be responsible for providing the Department of Natural Resources with sufficient technical information to make such determination.
1. All Development. All development within the areas of significant flood hazard shall:
A. Be consistent with the need to minimize flood damage.
B. Use construction methods and practices that will minimize flood damage.
C. Use construction materials and utility equipment that are resistant to flood damage.
D. Obtain all other necessary permits from Federal, State and local governmental agencies including approval when required from the Iowa Department of Natural Resources.
2. Residential Buildings. All new or substantially improved residential structures shall have the lowest floor, including basement, elevated a minimum of one foot above the 100-year flood level. Construction shall be upon compacted fill which shall, at all points, be no lower than one foot above the 100-year flood level and extend at such elevation at least 18 feet beyond the limits of any structure erected thereon. Alternate methods of elevating (such as piers) may be allowed, subject to favorable consideration by the City Council, where existing topography, street grades, or other factors preclude elevating by fill. In such cases, the methods used must be adequate to support the structure as well as withstand the various forces and hazards associated with flooding. All new residential structures shall be provided with a means of access which will be passable by wheeled vehicles during the 100-year flood.
3. Nonresidential Buildings. All new or substantially improved nonresidential buildings shall have the lowest floor (including basement) elevated a minimum of one foot above the 100-year flood level, or together with attendant utility and sanitary systems, be flood-proofed to such a level. When flood proofing is utilized, a professional engineer registered in the State shall certify that the flood proofing methods used are adequate to withstand the flood depths, pressures, velocities, impact and uplift forces and other factors associated with the 100-year flood; and that the structure, below the 100-year flood level, is watertight with walls substantially impermeable to the passage of water. A record of the certification indicating the specific elevation (in relation to National Geodetic Vertical Datum) to which any structures are flood-proofed shall be maintained by the Administrator.
4. All New and Substantially Improved Structures.
A. Fully enclosed areas below the “lowest floor” (not including basements) that are subject to flooding 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 meet or exceed the following minimum criteria:
(1) A minimum of two 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 above grade.
(3) Openings may be equipped with screens, louvers, valves, or other coverings or devices provided that they permit the automatic entry and exit of floodwaters.
Such areas shall be used solely for parking of vehicles, building access, and low damage potential storage.
B. New and substantially improved structures must be designed (or modified) and adequately anchored to prevent flotation, collapse, or lateral movement of the structure resulting from hydrodynamic and hydrostatic loads, including the effects of buoyancy.
C. New and substantially improved structures must be constructed with electrical, heating, ventilation, plumbing, and air conditioning equipment and other service facilities that are designed and/or located so as to prevent water from entering or accumulating within the components during conditions of flooding.
5. Factory-Built Homes.
A. All factory-built homes, including those placed in existing factory-built home parks or subdivisions, shall be elevated on a permanent foundation such that the lowest floor of the structure is a minimum of one foot above the 100-year flood level.
B. All factory-built homes, including those placed in existing factory-built home parks or subdivisions, shall be anchored to resist flotation, collapse, or lateral movement. Methods of anchoring may include, but are not limited to, use of over-the-top or frame ties to ground anchors.
6. Utility and Sanitary Systems.
A. On-site waste disposal and water supply systems shall be located or designed to avoid impairment to the system or contamination from the system during flooding.
B. All new and replacement sanitary sewage systems shall be designed to minimize or eliminate infiltration of floodwaters into the system as well as the discharge of effluent into floodwaters. Wastewater treatment facilities (other than on-site systems) shall be provided with a level of flood protection equal to or greater than one foot above the 100-year flood elevation.
C. New or replacement water supply systems shall be designed to minimize or eliminate infiltration of floodwaters into the system. Water supply treatment facilities other than on-site systems shall be provided with a level of protection equal to or greater than one foot above the 100-year flood elevation.
D. Utilities such as gas or electrical systems shall be located and constructed to minimize or eliminate flood damage to the system and the risk associated with such flood damaged or impaired systems.
7. Flammable or Explosive Materials. Storage of equipment and materials that are flammable, explosive, or injurious to human, animal or plant life is prohibited unless elevated a minimum of one foot above the 100-year flood level. Other material and equipment must either be similarly elevated or: (i) not subject to major flood damage and anchored to prevent movement due to floodwaters; or (ii) readily removable from the area within the time available after flood warning.
8. Levees and Floodwalls. Flood control structural works such as levees, floodwalls, etc. shall provide, at a minimum, protection from a 100-year flood with a minimum of three feet of design freeboard and shall provide for adequate interior drainage. In addition, structural flood control works shall be approved by the Department of Natural Resources.
9. Watercourse Alterations. Watercourse alterations or relocations must be designed to maintain the flood carrying capacity within the altered or relocated portion. In addition, such alterations or relocations must be approved by the Department of Natural Resources.
10. Subdivisions. Subdivisions (including factory-built home parks and subdivisions) shall be consistent with the need to minimize flood damages and shall have adequate drainage provided to reduce exposure to flood damage. Development associated with subdivision proposals (including the installation of public utilities) shall meet the applicable performance standards of this chapter. Subdivision proposals intended for residential use shall provide all lots with a means of access which will be passable by wheeled vehicles during the 100-year flood. Proposals for subdivisions greater than five acres or 50 lots (whichever is less) shall include 100-year flood elevation data for those areas located within the area of significant flood hazard.
11. Accessory Structures to Residential Uses.
A. Detached garages, sheds, and similar structures that are incidental to a residential use are exempt from the base flood elevation requirements where the following criteria are satisfied.
(1) The structure shall be designed to have low flood damage potential. Its size shall not exceed 600 square feet. Those portions of the structure located less than 1 foot above the BFE must be constructed of flood-resistant materials.
(2) The structure shall be used solely for low flood damage potential purposes such as vehicle parking and limited storage. The structure shall not be used for human habitation.
(3) The structure shall be constructed and placed on the building site so as to offer minimum resistance to the flow of floodwaters.
(4) The structure shall be firmly anchored to resist flotation, collapse and lateral movement.
(5) The structure's service facilities such as electrical and heating equipment shall be elevated or floodproofed to at least one foot above the base flood elevation.
(6) The structure's walls shall include openings that satisfy the provisions of Section 165.08 (4) A of this Ordinance.
B. Exemption from the 100-year flood elevation requirements for such a structure may result in increased premium rates for flood insurance coverage of the structure and its contents.
(Ord. 1706 - Sep. 17 Supp.)
12. Recreational Vehicles.
A. Recreational vehicles are exempt from the requirements of Section 165.08(5) of this chapter regarding anchoring and elevation of factory-built homes when the following criteria are satisfied.
(1) The recreational vehicle shall be located on the site for less than 180 consecutive days, and
(2) The recreational vehicle must be fully licensed and ready for highway use. A recreational vehicle is ready for highway use if it is on its wheels or jacking system and is attached to the site only by quick disconnect type utilities and security devices and has no permanently attached additions.
B. Recreational vehicles that are located on the site for more than 180 consecutive days or are not ready for highway use must satisfy requirements of Section 165.08(5) of this chapter regarding anchoring and elevation of factory-built homes.
13. Pipelines. Pipeline river and stream crossings shall be buried in the streambed and banks, or otherwise sufficiently protected to prevent rupture due to channel degradation and meandering.
In addition to the general flood plain standards, uses within the floodway must meet the following applicable standards. The floodway is that portion of the flood plain which must be protected from developmental encroachment to allow the free flow of floodwaters. Where floodway data has been provided in the flood insurance study, such data shall be used to define the floodway. Where no floodway data has been provided, the Department of Natural Resources shall be contacted to provide a floodway delineation. The applicant will be responsible for providing the Department of Natural Resources with sufficient technical information to make such determination.
1. No use shall be permitted in the floodway that would result in any increase in the 100-year flood level. Consideration of the effects of any development on flood levels shall be based upon the assumption that an equal degree of development would be allowed for similarly situated lands.
2. All uses within the floodway shall:
A. Be consistent with the need to minimize flood damage.
B. Use construction methods and practices that will minimize flood damage.
C. Use construction materials and utility equipment that are resistant to flood damage.
3. No use shall affect the capacity or conveyance of the channel or floodway of any tributary to the main stream, drainage ditch or any other drainage facility or system.
4. Structures, buildings, and sanitary and utility systems, if permitted, shall meet the applicable general flood plain standards and shall be constructed or aligned to present the minimum possible resistance to flood flows.
5. Buildings, if permitted, shall have a low flood damage potential and shall not be for human habitation.
6. Storage of equipment or materials that are buoyant, flammable, explosive, or injurious to human, animal or plant life is prohibited. Storage of other material may be allowed if readily removable from the floodway within the time available after flood warning.
7. Watercourse alterations or relocations (channel changes and modifications) must be designed to maintain the flood carrying capacity within the altered or relocated portion. In addition, such alterations or relocations must be approved by the Department of Natural Resources.
8. Any fill allowed in the floodway must be shown to have some beneficial purpose and shall be limited to the minimum amount necessary.
9. Pipeline river or stream crossings shall be buried in the streambed and banks or otherwise sufficiently protected to prevent rupture due to channel degradation and meandering or due to the action of flood flows.
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