(A) Lands to which this district applies.
(1) The provisions of this Overlay District shall apply to all lands within the jurisdiction of the City of Urbandale which are designated as FLOODWAY FRINGE.
(2) Parcels that at any time are or have been required to comply with minimum floor elevation requirements, whether by location within the Floodway Fringe of a Flood Insurance Rate Map; localized flooding conditions; or otherwise required by the city as a condition of subdivision approval or of the issuance of a building permit, shall continue to comply with such minimum floor elevation requirements regardless of whether such parcel or property may be all or in part removed from the flood hazard area as identified by FEMA by reason of approval of a Letter of Map Revision based on Fill (LOMR-F). The city finds that flood hazards continue to exist for such properties, including but not limited to reasons expressly identified by FEMA, and continued and perpetual compliance with the minimum floor elevation requirements is reasonable and necessary to protect public health, safety and welfare, and to protect and preserve property values.
(B) Permitted uses. All uses within the Floodway Fringe District shall be permitted to the extent that they are permitted by any underlying zoning district and provided they meet applicable performance standards of the Floodway Fringe Districts as set forth in division (C) C below.
(C) Performance standards. All uses shall be consistent with the need to minimize flood damage and shall meet the following applicable performance standards.
(1) Structures other than buildings. All structures and manufactured dwelling units that are not attached to permanent foundations shall:
(a) Be adequately anchored to prevent flotation, collapse or lateral movement resulting from hydrodynamic and hydrostatic loads, including the effects of buoyancy;
(b) Be constructed with mechanical, electrical, utility equipment designed or located to prevent flood waters from entering or accumulating in said equipment; and
(c) Be constructed by methods and practices and of flood-resistance materials that minimize flood damage.
(2) Residential buildings.
(a) All new or substantially improved residential buildings, manufactured dwelling units and accessory buildings thereto shall have the lowest floor thereof, including basements, elevated a minimum of one foot above the elevation of the base flood. Construction or placement of all such buildings shall be upon compacted fill that is at all points a minimum of one foot above the base flood elevation, for a minimum distance of 18 feet beyond the limits of any building.
(b) Alternate methods of elevating (such as piers) may be allowed, but only if topographic conditions, existing street grades or other factors preclude elevating by fill to the extent of being deemed confiscatory. In such cases, a professional engineer registered in the State of Iowa shall design and certify that the proposed construction will be adequate to support the structure as well as withstand the various forces and hazards associated with flooding. Not more than 40% of the perimeter of the area below the lowest floor shall be enclosed by supports, walls, screens, louvers or other devices. Such area shall be unfinished and shall not be used for any purpose, except parking of vehicles and access to the building from the exterior. The bottom of all openings shall be no higher than one foot above grade and shall allow for the entry and exit of floodwaters to automatically equalize hydrostatic flood forces. All materials shall be impervious to water damage.
(c) All new dwelling units shall be provided with an access drive that is designed for use by any automobile and that is completely above the elevation of the base flood elevation.
(3) Nonresidential buildings. All new or substantially improved non-residential buildings shall have the lowest floor (including basement) elevated a minimum of one foot above the base flood elevation, or together with attendant utility and sanitary systems, be floodproofed to such a level. When floodproofing is utilized, a professional engineer registered in the State of Iowa shall certify that the design and methods of construction are adequate to withstand the flood depths, pressures, velocities, impact and uplift forces and other factors associated with the base flood; and that the structure, below the base flood elevation, is watertight with walls substantially impermeable to the passage of water. A record of the certification indicating the specific elevation (in relation to mean sea level) to which any structures are floodproofed shall be maintained by the Administrator.
(4) Mechanical equipment, and utility, water and sanitary systems.
(a) Electrical, heating, ventilation, plumbing, air-conditioning equipment and other service facilities shall be elevated a minimum of one foot above the base flood elevation.
(b) All new and replacement sanitary sewage systems shall be designed to minimize or eliminate infiltration of flood waters. Wastewater treatment facilities shall be provided with a level of flood protection equal to or greater than one foot above the base flood elevation.
(c) On-site waste disposal systems shall be located or designed to avoid impairment to the system or contamination from the system during flooding.
(d) New or replacement water supply systems shall be designed to minimize or eliminate infiltration of flood waters into the system. Water supply treatment facilities shall be provided with a level of protection equal to or greater than one foot above the base flood elevation.
(e) Utilities such as gas and 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.
(5) Flammable, explosive or injurious materials. Storage of materials and equipment that are flammable, explosive or injurious to human, animal or plant life is prohibited unless elevated a minimum of one foot above the base flood elevation. Other material and equipment shall either be similarly elevated or not be subject to major flood damage and be anchored to prevent movement due to flood waters.
(6) Minimum protections. Flood control structural works such as levees, floodwalls and the like shall provide, at a minimum, protection from the base 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.
(7) No impeding qualities. No use shall impede or reduce the capacity or conveyance of the channel or floodway of any tributary to the main stream, drainage ditch or other drainage facility or system.
(8) Subdivisions. Subdivisions shall be designed to minimize flood damages and shall have adequate drainage provided to reduce exposure to flood damages. Development associated with subdivision proposals (including the installation of public utilities) shall meet the applicable performance standards of this chapter. Subdivision improvements shall meet all applicable performance standards, including but not limited to streets and all other means of vehicular access to lots being designed to be at all points a minimum of one foot above the elevation of the base flood. All subdivision proposals, regardless of size or number of lots, shall include base flood elevation data for those areas located within the Floodway Fringe Overlay District.
(9) Manufactured dwelling units; anchoring. Manufactured dwelling units that are located in a manufactured dwelling unit park and that are subject to the stresses of flooding shall be anchored to resist flotation, collapse or lateral movement by providing over-the-top and frame ties to ground anchors. Specific requirements are that:
(a) Over-the-top ties be provided at each of the four corners of the factory-built dwelling unit with two additional ties per side at intermediate locations for factory-built dwelling units 50 feet or more in length or one such tie for factory-built dwelling units less than 50 feet in length;
(b) Frame ties be provided at each corner of the factory-built dwelling units with five additional ties per side at intermediate points for factory-built dwelling units 50 feet or more in length or four such ties for said dwelling units less than 50 feet in length;
(c) All components of the anchoring system be capable of carrying a force of 4,800 pounds; and
(d) Any additions to the factory-built dwelling units shall be similarly anchored.
(10) Manufacture dwelling units; reinforcement. Manufactured dwelling units that are located in a manufactured dwelling park shall be elevated by means of compacted fill or permanently placed reinforced piers or other foundation elements of at least equivalent strength such that the lowest floor of the unit and any addition thereto is a minimum of one foot above the base flood elevation. At a minimum, reinforced piers shall include a footing extending below the frost depth and designed to support the weight of the dwelling under saturated soil conditions, and shall be designed and certified by a professional engineer registered in the State of Iowa as being adequate to withstand the stresses caused by flooding.
(11) Recreational vehicle spaces, campsites. Recreational vehicle spaces or campsites shall be elevated by means of compacted fill such that all spaces or campsites are elevated a minimum of one foot above the base flood elevation.
(Am. Ord. 2018-18, passed 1-2-2019)