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:
Non-Precision Instrument Runway | (1) 4,000 feet for Runway 23 |
Precision Instrument Runway | (2) 16,000 feet for all other runways |
(2) The Approach Surface extends for a horizontal distance of:
Non-Precision Instrument Runway | (1) 10,000 feet at a slope of 34 to 1 for Runway 23 |
Precision Instrument Runway | (2) 10,000 feet at a slope of 50 to 1, and then 40,000 feet at a slope of 40 to 1. |
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.
(Ord. 23-09 - Dec. 23 Supp.)
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.