The regulations set forth in this section or elsewhere in this ordinance which are applicable, shall apply in the FW Floodway Overlay District.

   1.   Principal Permitted Uses. The following uses shall be permitted within the FW Floodway Overlay District to the extent they are not prohibited by any other ordinance (or underlying zoning district) and provided they do not include placement of structures, buildings, factory built homes, fill or other obstruction, the storage of materials or equipment, excavation, or alteration of a watercourse.

      A.   Agricultural uses such as general farming, pasture, grazing, outdoor plant nurseries, horticulture, viticulture, aquaculture, truck farming, forestry, sod farming, wild crop harvesting, but not including livestock feed lots or poultry farms.

      B.   Private and public recreational uses such as golf courses, tennis courts, driving ranges, archery ranges, picnic grounds, boat launching ramps, swimming areas, parks, wildlife and nature preserves, game farms, fish hatcheries, fishing areas, hiking, biking and horseback riding trails.

      C.   Open space uses such as lawns and gardens.

      D.   Such other open-space uses similar in nature to the above uses.

   2.   Permitted Accessory Uses. The following uses may exist as part of, or in accessory to the principal permitted uses:

      A.   Accessory uses customarily incidental to a principal permitted use, provided all restrictions on development in the FW District shall apply to any accessory uses.

      B.   Floating and removable docks for residential uses, provided the standards of Subsection 4 of this section (Performance Standards) are met.

   3.   Special Uses. The following uses which involve structures (temporary or permanent), fill, storage of materials or equipment may be permitted only upon approval of a special use permit and only when adequate public liability insurance is provided. Such uses must also meet the applicable provisions of the Floodway District Performance Standards and the standards allowed usage of the appropriate underlying zoning district.

      A.   Extraction of sands, gravel, and other materials.

      B.   Marinas, boat rentals, permanently installed docks, piers, and wharves.

      C.   Utility transmission lines and underground pipelines.

      D.   Other uses similar in nature to uses described in this subsection which are consistent with the provisions and the general spirit and purpose of this subsection.

   4.   Performance Standards. All FW Floodway Overlay Zoning District uses allowed as a principal permitted use, accessory use or special use, shall meet the following standards:

      A.   No development shall be permitted in the Floodway District that would result in any increase in the base flood elevation. 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.

      B.   All development within the Floodway District shall:

         (1)   Be consistent with the need to minimize flood damage.

         (2)   Use construction methods and practices that will minimize flood damage.

         (3)   Use construction materials and utility equipment that are resistant to flood damage.

      C.   No development 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.

      D.   Structures, buildings, recreational vehicles, and sanitary and utility systems, if permitted, shall meet the applicable performance standards of the Floodway Fringe District and shall be constructed or aligned to present the minimum possible resistance to flood flows.

      E.   Structures, if permitted, shall have a low flood damage potential and shall not be for human habitation.

      F.   Storage of materials or equipment that are buoyant, flammable, explosive, hazardous, or injurious to human, animal, or plant life is prohibited. Storage of other material may be allowed if readily removable from the FW District within the time available after flood warning.

      G.   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 Iowa Department of Natural Resources.

      H.   Any fill allowed in the FW District shall not increase the one hundred (100) year flood profile.

      I.   Pipeline crossings of streams or rivers shall be buried in the stream bed and banks or otherwise sufficiently protected to prevent rupture due to channel degradation and meandering or due to the action of flood flows.

The regulations set forth in this section or elsewhere in this ordinance which are applicable, shall apply in the FF Floodway Fringe Overlay Zoning District.

   1.   Principal Permitted Uses: All development within the Floodway Fringe District shall be permitted to the extent that they are not prohibited by any other ordinance (or underlying zoning district) and provided they meet applicable performance standards of the Floodway Fringe District.

   2.   Performance Standards. All development must be consistent with the need to minimize flood damage and meet the following applicable performance standards. Until a regulatory floodway is designated, no development may increase the Base Flood Elevation more than one (1) foot. The applicant will be responsible for providing the Department of Natural Resources with sufficient technical information to make such determination.

      A.   No development within the Floodway Fringe Overlay Zoning District shall increase the flood heights or flood profile.

      B.   All development shall:

         (1)   Be designed and adequately anchored to prevent flotation, collapse or lateral movement.

         (2)   Use construction methods and practices that will minimize flood damage.

         (3)   Use construction materials and utility equipment that are resistant to flood damage.

      C.   Non-residential structures - All new or substantially improved non-residential structures shall have the lowest floor (including basement) elevated a minimum of one (1) 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 floodproofing methods used 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 North American Vertical Datum 1988) to which any structures are floodproofed shall be maintained by the Administrator.

      D.   Residential structures - All new or substantially improved residential structures shall have the lowest floor, including basement, elevated a minimum of one (1) foot above the base flood elevation. Construction shall be upon compacted fill which shall, at all points, be no lower than 1.0 ft. above the base flood elevation and extend at such elevation at least 18 feet beyond the limits of any structure erected thereon. Alternate methods of elevating (such as piers or extended foundations) may be allowed 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 located in areas that would become isolated due to flooding of surrounding ground shall be provided with a means of access that will be passable by wheeled vehicles during the base flood. However, this criterion shall not apply where the Administrator determines there is sufficient flood warning time for the protection of life and property. When estimating flood warning time, consideration shall be given to the criteria listed in 567- 75.2(3), Iowa Administrative Code.

      E.   All New and Substantially Improved Structures. Fully enclosed areas below the lowest floor (not including basement) 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 floodwater. Designs for meeting this requirement must 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 (1) 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 (1) foot above grade.

         (3)   Openings may be equipped with screens, louvers, valves, or other coverings or devices provided they permit the automatic entry and exit of floodwaters.

         (4)   All such areas shall be used solely for parking of vehicles, building access, and low damage potential storage.

      F.   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.

      G.   New and substantially improved structures shall be constructed with electric meter, electrical service panel box, hot water heater, heating, air conditioning, ventilation equipment (including ductwork), and other similar machinery and equipment elevated (or in the case of non-residential structures, optionally floodproofed to) a minimum of one (1) foot above the base flood elevation.

      H.   New and substantially improved structures shall be constructed with plumbing, gas lines, water/gas meters and other similar service utilities either elevated (or in the case of non- residential structures, optionally floodproofed to) a minimum of one (1) foot above the base flood elevation or designed to be watertight and withstand inundation to such a level.

         (1)   All new and replacement sanitary sewage systems shall be designed to minimize or eliminate infiltration of flood waters into the system as well as the discharge of effluent into flood waters. Wastewater treatment facilities (other than on-site systems) shall be provided with a level of flood protection equal to or greater than one (1) foot above the base flood elevation.

         (2)   On site waste disposal systems shall be located or designed to avoid impairment to the system or contamination from the system during flooding.

         (3)   New or replacement water supply systems shall be designed to minimize or eliminate infiltration of flood waters 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 (1) foot above the base flood elevation.

         (4)   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 flood damaged or impaired system.

      I.   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 (1) foot above the base flood elevation. Other material and equipment must either be similarly elevated or (i) not be subject to major flood damage and be anchored to prevent movement due to flood waters or (ii) be readily removable from the area within the time available after flood warning.

      J.   Flood control structural works such as levees, flood walls, etc. shall provide, at a minimum, protection from the base flood within a minimum of 3 ft. of design freeboard and shall provide for adequate interior drainage. In addition, the Department of Natural Resources shall approve structural flood control works..

      K.   Watercourse alterations or relocations must be designed to maintain the flood carrying capacity within the altered or relocated portion. In addition, the Department of Natural Resources must approve such alterations or relocations.

      L.   Accessory Structures to Residential Uses. 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 in size. Those portions of the structure located less than one 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 Paragraph 2(E) of this section.

         (7)   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.

      M.   Factory-Built Homes.

         (1)   All new and substantially improved 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 (1) foot above the base flood elevation.

         (2)   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 as required by the State Building Code.

      N.   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 Ordinance. Subdivision proposals intended for residential use shall provide all lots with a means of access which will be passable by wheeled vehicles during the base flood. Proposals for subdivisions greater than five (5) acres or fifty (50) lots (whichever is less) shall include base flood elevation data for those areas located within the Floodway Fringe (Overlay) District.

      O.   Recreational vehicles are exempt from the requirements of Paragraph M of this subsection 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.

   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 Paragraph M of this section regarding anchoring and elevation of factory- built homes.

      P.   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.

      Q.   Maximum Damage Potential Development - All new or substantially improved maximum damage potential development shall have the lowest floor (including basement) elevated a minimum of one (1) foot above the elevation of the 500-year flood, 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 floodproofing methods used are adequate to withstand the flood depths, pressures, velocities, impact and uplift forces and other factors associated with the 0.2% annual chance flood; and that the structure, below the 0.2% annual chance 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 North American Vertical Datum 1988) to which any structures are floodproofed shall be maintained by the Administrator. Where 0.2% chance flood elevation data has not been provided in the Flood Insurance Study, the Iowa Department of Natural Resources shall be contacted to compute such data. The applicant will be responsible for providing the Department of Natural Resources with sufficient technical information to make such determinations.

The regulations set forth in this section or elsewhere in this ordinance which are applicable, shall apply in the FP General Flood Plain Overlay District.

   1.   Permitted Uses.

      A.   All development within the General Floodplain District shall be permitted to the extent that they are not prohibited by any other ordinance (or underlying zoning district) and provided they meet the applicable performance standards of the General Floodplain District.

      B.   Any development which involves placement of structures, factory-built homes, fill or other obstructions, storage of materials or equipment, excavation or alteration of a watercourse shall be reviewed by the Department of Natural Resources to determine (i) whether the land involved is either wholly or partly within the floodway or floodway fringe and (ii) the base flood elevation. The applicant shall be responsible for providing the Department of Natural Resources with sufficient technical information to make the determination.

      C.   Review by the Iowa Department of Natural Resources is not required for the proposed construction of new or replacement bridges or culverts where:

         (1)   The bridge or culvert is located on a stream that drains less than two (2) square miles, and

         (2)   The bridge or culvert is not associated with a channel modification that constitutes a channel change as specified in 567-71.2(2), Iowa Administrative Code.

   2.   Performance Standards.

      A.   All development, or portions thereof, to be located in the floodway as determined by the Department of Natural Resources shall meet the applicable provisions and standards of the Floodway (Overlay) District in CH 175C.01.

      B.   All development, or portions thereof, to be located in the floodway fringe as determined by the Department of Natural Resources shall meet the applicable provisions and standards of the Floodway Fringe (Overlay) District in CH 175C.02.

The regulations set forth in this section or elsewhere in this ordinance which are applicable shall apply in the AZ Approach Zone, CZ Conical Zone, HZ Horizontal Zone, and TZ Transitional Zone Overlay Zoning Districts.

   1.   Statement of Intent. The Airport Hazard, Height, and Noise Mitigation Overlay Zoning Regulations are intended to prevent the creation or establishment of hazards which may affect the safe operations of the Des Moines International Airport, and to mitigate the effect of noise generated by the approach and departure of aircraft from the Airport upon incompatible noise-sensitive land uses.

   2.   Airport Zones and Airspace Height Limitations. In order to carry out the provisions of this subsection, there are hereby created and established certain zones, the boundaries of which are depicted as surfaces on the Des Moines International Airport’s Airport Layout Plan (ALP) which is currently on file at the Office of the Norwalk City Clerk and at the City of Des Moines Engineering Department under Plan File No. 335-111/113. A structure or tree located in more than one (1) zone of the following zones shall comply with the regulations of the zone with the more restrictive height limitation. The various zones are hereby established and defined as follows:

      A.   Approach Zone. The land lying under the Approach Surface, a surface longitudinally centered on the extended runway centerline and extending outward and upward from each end of the primary surface. (Note: An Approach Surface is applied to each end of each runway based upon the types of approach available or planned for that runway end.)

         (1)   The inner edge of the Approach Surface is the same width as the primary surface, and it expands uniformly to a width of:

 

         (2)   The Approach Surface extends for a horizontal distance of:

 

 

No structure or tree shall exceed the Approach Surface to any runway, as depicted on the Des Moines International Airport ALP.

      B.   Conical Zone. The land lying under the Conical Surface, a surface extending outward and upward from the periphery of the Horizontal Surface at a slope of 20 to 1 for a horizontal distance of 4,000 feet. No structure or tree shall exceed the Conical Surface in the Conical Zone, as depicted on the Des Moines International Airport ALP.

      C.   Horizontal Zone. The land lying under the Horizontal Surface, a plane 150 feet above the established airport elevation, the perimeter of which is constructed by: swinging arcs of 10,000 feet radii from the State Plane Coordinates at center of each end of the primary surface of all runways and connecting the adjacent arcs by lines tangent to those areas.

      D.   Transitional Zone. The land lying under the Transitional Surfaces. These surfaces extend outward and upward at right angles to the runway centerline and centerline extended from the sides of the primary surface and from the sides of the approach surfaces at a slope of 7 to 1 until said surfaces intersect the Horizontal or Conical Surfaces. Beyond the limits of the conical surface on all runway approaches except Runway 23 the Transitional Surfaces shall extend outward and upward at a slope of 7 to 1 from the sides of the Approach Surface for a distance of 5,000 feet measured horizontally from the edge of the Approach Surface and at right angles to the runway centerline extended. No structure or tree shall exceed the Transitional Surface, as depicted on the Des Moines International Airport ALP.

No structure shall be erected or tree allowed to grow in the City of Norwalk that raises the published Minimum Descent Altitude or Decision Height for an instrument approach to any runway, nor shall any structure be erected or tree allowed to grow that causes the Minimum Obstruction Clearance Altitude or Minimum En route Altitude to be increased on any Federal Airway in the City of Norwalk

   3.   Noise Attenuation. Any residential dwelling, hotel, motel, group quarters, school, hospital, auditorium, place of worship, or other place of public assembly proposed to be constructed within the Approach Zone and within areas of more than 65 dBA, as set forth as the area of noise attenuation on the attached map identified as Exhibit A, shall be constructed with soundproofing to achieve a noise level reduction of 25 dBA (outdoor and indoor). Construction standards to achieve this degree of sound attenuation are provided in the City of Norwalk Building Code. The development of land located within the first 10,000 feet of the Approach Zone, set forth in the map identified as Exhibit A, shall require the submission of a "Noise and Avigation Easement" to the City by the landowner as part of the City subdivision process and prior to initiation of building construction.

   4.   Use Restrictions. Notwithstanding any other provisions of Subsection 2 of this section, no use may be made of land or water within the zones defined in Subsection 2 in such manner as to interfere with the operation of any airborne aircraft. The following special requirements shall apply to each permitted use.

      A.   All lights or illumination used in conjunction with street, parking, signs or use of land and structures shall be arranged and operated in such a manner that it is not misleading or dangerous to aircraft operating from the airport or in the vicinity thereof.

      B.   No operations from any use shall produce smoke, glare, or other visual hazards which are sufficient to endanger aircraft operating from the airport or in the vicinity thereof. When the Aviation Director believes such a hazard may exist, a determination shall be obtained from the FAA as to the existence of such a hazard.

      C.   No operations from any use shall produce electronic interference with navigation signals or radio communication between the airport and aircraft.

   5.   Nonconforming Structures, Trees and Uses. No pre-existing nonconforming structure, tree, or use shall be replaced, rebuilt, altered, allowed to grow higher, or replanted, so as to constitute a greater airport hazard than it was when this subchapter was adopted.

   6.   Lighting.

      A.   Notwithstanding the provisions of Subsection 4 of this section, the owner of any structure or tree over 200 feet above ground level must install on the structure lighting in accordance with FAA Advisory Circular 70-7460-1D and amendments. Additionally, any structure, constructed after the effective date of this ordinance and exceeding 949 feet above ground level, must install on that structure high intensity white obstruction lights in accordance with Chapter 6 of FAA Advisory Circular 7460-1D and amendments.

      B.   A property owner shall permit the Des Moines International Airport at its own expense to install, operate, and maintain on such property markers and lights as necessary to indicate to operators of aircraft the presence of an airport hazard.

   7.   Variances. Any person desiring to erect or increase the height of any structure, or to permit the growth of any tree, or otherwise use his or her property in violation of any section of this subchapter may apply to the Board of Adjustment for a variance from such regulations. No application for a variance to the requirements of this subchapter may be considered by the Board of Adjustment unless a copy of the application has been submitted to the Aviation Director for his or her opinion as to the aeronautical effects of such a variance. If the Aviation Director responds to the Board of Adjustment in favor of the variance, or if he or she does not respond within fifteen (15) days from receipt of the copy of the application, then the Board shall make its decision to grant or deny the variance based upon a preponderance of the evidence. If the Aviation Director responds in opposition to the variance within fifteen (15) days from receipt of the copy of the application, then the Board may grant the variance only if clear and convincing evidence outweighs the opinion of the Aviation Director.

   8.   Board of Adjustment. The Board of Adjustment appointed pursuant to Section 175A.20 shall have and exercise the following powers:

      A.   To hear and decide appeals from any order, requirement, decision, or determination made by the Administrative Agency in the enforcement of this subsection.

      B.   To hear and decide special exemptions to the terms of this subsection upon which such Board of Adjustment under such regulations may be required to pass.

      C.   To hear and decide specific variances.

   9.   Judicial Review. Any persons aggrieved, or any taxpayer affected, by any decision of the Board of Adjustment, in the administration of this subsection, may appeal to a court of record as provided in Sec. 414.15, Code of Iowa.

   10.   Administration. The Zoning Administration is hereby designated as the administrative agency pursuant to Sec. 329.13 of the Code of Iowa, with the duty to administer the regulations prescribed in this section. Administration and enforcement of this section shall be in accordance with the procedures set forth in Section 175A.09.

   11.   Conflicting Regulations. Where there exists a conflict between any of the regulations or limitations prescribed in this subchapter and any other regulations applicable to the same area, whether the conflict be with respect to height of structures, or trees, the use of land, or any other matter, the more stringent limitation or requirement shall govern and prevail.