The purpose of the Airport Safety Overlay District (ASOD) is to provide for the safety of aircraft pilots and passengers and protect a substantial investment of public funds by assuring that land development and construction activities within the ASOD are compatible with the safe continued use of the American Falls and Pocatello Airports. (Ord. 2019-01, 1-14-2019)

This Overlay Zoning District is composed of several height limitation zones, which include all land lying beneath the approach surfaces, transitional surfaces, horizontal surfaces, and conical surfaces appurtenant to the American Falls and Pocatello Airports. These zones are shown on supplements to the Official Zoning Map established by section 10-3-3 of this title. An area located in more than one of these zones shall be considered to be in the zone with the more restrictive height limitation.

   A.   Approach Zones:

      1.   American Falls Airport: The inner edge of this approach zone coincides with the width of the primary surface and is two hundred fifty feet (250') wide. This approach zone expands uniformly outward to a width of one thousand two hundred fifty feet (1,250') at a horizontal distance of five thousand feet (5,000') from the end of the primary surface. Its center line is the continuation of the center line of the runway.

      2.   Pocatello Airport:

         a.   Runway 16/34: The inner edge of this approach zone coincides with the width of the primary surface and is five hundred feet (500') wide. This approach zone expands uniformly outward to a width of one thousand five hundred feet (1,500') at a horizontal distance of five thousand feet (5,000') from the end of the primary surface. Its center line is the continuation of the center line of the runway.

         b.   Runway 03/21: The inner edge of this approach zone coincides with the width of the primary surface and is one thousand feet (1,000') wide. To the northeast, this approach zone expands uniformly outward to a width of sixteen thousand feet (16,000') at a horizontal distance of fifty thousand feet (50,000') from the end of the primary surface. Its center line is the continuation of the center line of the runway. To the southwest, this approach zone expands uniformly outward to a width of three thousand five hundred feet (3,500') at a horizontal distance of ten thousand feet (10,000') from the end of the primary surface. Its center line is the continuation of the center line of the runway.

   B.   Conical Zones: The conical zone commences at the outer edge of the horizontal zone and extends outward a horizontal distance of four thousand feet (4,000').

   C.   Horizontal Zones:

      1.   American Falls Airport: The horizontal zone is established by swinging arcs of five thousand feet (5,000') from the center of each end of the primary surface and connecting the adjacent arcs by drawing lines tangent to those arcs. The horizontal zone does not include the approach and transitional zones.

      2.   Pocatello Airport: The horizontal zone is established by swinging arcs of ten thousand feet (10,000') from the center of each end of the primary surface of Runway 03/21 and connecting the adjacent arcs by drawing lines tangent to those arcs. The horizontal zone does not include the approach and transitional zones.

   D.   Transitional Zones: The transitional zones are beneath the transitional surfaces defined in section 10-10-3 of this chapter. (Ord. 2019-01, 1-14-2019)

Except as provided in subsection E of this section, or by variance, no structure or tree shall be allowed to break the plane of the imaginary surfaces established herein.

   A.   Approach Surfaces:

      1.   American Falls Airport And Pocatello Airport Runway 16/34: This surface is above the approach zones for these runways and slopes twenty feet (20') outward for each foot upward beginning at the end of and same elevation as the primary surface, then extending along the extended runway center line to the end of the approach zone.

      2.   Pocatello Airport Runway 03/21: This surface is above the approach zones for this runway. To the northeast it slopes fifty feet (50') outward for each foot upward beginning at the end of and same elevation as the primary surface, and extending to a horizontal distance of ten thousand feet (10,000') along the extended runway center line, then forty feet (40') outward for each foot upward to the end of the approach zone. To the southwest it slopes thirty four feet (34') outward for each foot upward beginning at the end of and same elevation as the primary surface, then extending along the extended runway center line to the end of the approach zone.

   B.   Conical Surface: These surfaces slope twenty feet (20') outward for each foot upward beginning at the edge of the horizontal surface and extending for a horizontal distance of four thousand feet (4,000').

   C.   Horizontal Surface: A horizontal plane one hundred fifty feet (150') above the established airport elevation, the perimeter of which, in plan view, coincides with the perimeter of the horizontal zone established in subsection 10-10-2C of this chapter.

   D.   Transitional Surface: These surfaces extend outward at ninety degree (90°) angles to the runway center line and the runway center line extended at a slope of seven to one (7:1) from the sides of the primary and approach surfaces to where they intersect the horizontal and conical surfaces.

   E.   Exception From Height Limitations: Nothing in this chapter shall prohibit the construction or maintenance of any structure of thirty five feet (35') or less in height, or the growth of any tree to a height up to thirty five feet (35') above the surface of the land, except in the approach zones. (Ord. 2019-01, 1-14-2019)

No use shall create electrical interference with navigational signals or radio communication between the airport and aircraft, make it difficult for pilots to distinguish between airport lights and other lights, result in glare in the eyes of pilots using the airport, impair visibility in the vicinity of the airport, create bird strike hazards, or in any way endanger or interfere with the operation of aircraft. Note that this performance standard applies throughout the County. (Ord. 2019-01, 1-14-2019)

Nonconforming uses and buildings are regulated by the provisions of subsection 10-1-4C of this title and, within this Overlay District, these additional requirements:

   A.   Nonconforming uses, which may include trees, shall be required to permit the installation, operation, and maintenance of any markers and/or lights Power County or the City of Pocatello deem necessary to indicate their presence to the operators of aircraft. Such markers and lights shall be installed, operated, and maintained at the expense of Power County or the City of Pocatello.

   B.   The repair and, under specified circumstances, replacement of nonconforming uses and buildings is permitted by subsection 10-1-4C of this title, but no nonconforming use, building, or tree shall be permitted to become a greater hazard to air navigation than it was on the effective date hereof. (Ord. 2019-01, 1-14-2019)

Permit requirements for development activity are established in chapter 2 of this title. Within the ASOD, permit requirements shall be expanded to include the planting of any tree with a growth habit of more than thirty five feet (35') and the construction of any building or structure that is more than thirty five feet (35') in height and is exempted from the requirement for a permit by subsection 10-2-2C of this title. (Ord. 2019-01, 1-14-2019)

The variance procedure is described in subsection 10-2-3B of this title. Any application for a variance of the height limitations established for the ASOD shall be accompanied by a determination from the Federal Aviation Administration as to the effect of the proposal on the operation of air navigation facilities and the safe, efficient use of navigable airspace. (Ord. 2019-01, 1-14-2019)

The approval of any application for a permit or variance within the ASOD may be conditioned on the installation, operation, and maintenance, at the owner's expense, of the markings and/or lights necessary to indicate the presence of an obstruction to aircraft operators. (Ord. 2019-01, 1-14-2019)

Maps depicting the airport imaginary surfaces of the American Falls and Pocatello Airports shall be on file in the Office of the County Clerk. (Ord. 2019-01, 1-14-2019)