10-40.50

Division 10-40.50:
Overlay Zones

Sections:

10-40.50.040 AO Zone Additional Requirements

10-40.50.010 Purpose

This division provides regulatory standards governing land use and building form within the overlay zones. These standards are intended to ensure that proposed development is compatible with existing and future development and produces an environment of desirable character consistent with the General Plan. The General Plan along with the underlying zones shall guide appropriate densities in the overlay zones.

10-40.50.020 Applicability

The requirements of this division shall apply to all proposed development within overlay zones, and shall be considered in combination with the standards in Chapter 10-50, Supplemental to Zones, and Division 10-40.60, Specific to Uses. If there is a conflict between any standards, the provisions of this division control over Chapter 10-50, Supplemental to Zones, and the provisions of Division 10-40.60, Specific to Uses, control over this division and Chapter 10-50, Supplemental to Zones.

Refer to Chapter 10-90, Maps, for application of the overlay zones on the Zoning Map.

10-40.50.030 Overlay Zones

A. Intent.

1. AO. The Airport Overlay (AO) zone applies to areas of the City in the vicinity of the City’s Pulliam Municipal Airport.

a. The zone ensures that land uses in the airport area are mutually compatible with the operation of the airport and that any public investment in the airport is protected. In addition, the AO zone shall also have the following purposes:

(1) The AO zone is established for the general purpose of controlling conflicts between land uses and noise generated by aircraft and to protect the public health, safety, and welfare from adverse impacts associated with excessive noise. The AO zone shall also provide acoustical performance standards as set forth in Section 10-40.50.040, AO Zone Additional Requirements.

(2) The AO zone is further intended to regulate land uses within designated existing or projected airport impact areas by providing height restrictions which will assure safe, unobstructed access for all aircraft which enter and exit Pulliam Airport.

b. This zone is mapped in Section 10-90.30.020, Airport Overlay Map.

2. DO. The Downtown Overlay (DO) zone applies to areas of the City subject to the Design Handbook for Downtown Flagstaff for the development of properties located within the boundaries of the zone.

a. The requirements of the DO zone are intended to promote the preservation and unique character of all structures within the zone.

b. This zone is mapped in Section 10-90.30.030, Downtown Historic District Overlay Map.

3. LO. The Landmarks Overlay (LO) zone applies to areas of the City subject to the Landmark Design Review Overlay District Design Standards and Guidelines and design review by the Heritage Preservation Commission for the development of properties located within the boundaries of the zone.

a. The requirements of the LO zone are intended to promote the preservation and unique character of all structures within the zone.

4. RPO. The Resource Protection Overlay (RPO) zone applies to areas of the City that warrant protection of natural resources, including floodplains, steep slopes, and forests.

a. The requirements of the RPO zone are intended to maintain existing natural resources and to ensure that proposed development is consistent with the character of its natural surroundings. Within this zone, projects will be designed to incorporate native habitat and natural features on site as they provide important visual, environmental, health, and economic benefits. (See Division 10-50.90, Resource Protection Standards, for the purpose of the RPO zone, and additional standards.)

b. This zone is mapped in Section 10-90.30.050, Resource Protection Overlay Zone Map.

5. TO. The Townsite Overlay (TO) zone applies to areas of the City subject to the Townsite Historic Design Review Overlay District Design Standards and Guidelines and design review by the Heritage Preservation Commission for the development of properties located within the boundaries of the zone.

a. The requirements of the TO zone are intended to promote the preservation and unique character of the zone and all structures within the zone.

b. This zone is mapped in Section 10-90.30.060, Townsite Overlay Zone Map.

B. Allowed Uses.

Land Use	Overlay Zones
Land Use	AO	DO	LO	RPO	TO
——————————————————Refer to underlying zoning——————————————————

C. Building Form Standards.

Building Form Standards		AO	TO
Building Placement Requirements
Setback
Front		—————————Refer to underlying zoning—————————
Side		—————————Refer to underlying zoning—————————
Side Exterior		—————————Refer to underlying zoning—————————
Rear		—————————Refer to underlying zoning—————————
Building Form Requirements
Building Height
Primary Structure		——————Refer to underlying zoning——————	25'1, 2, 3
All Other Structures		——————Refer to underlying zoning——————	16'1, 2, 3
Coverage		—————————Refer to underlying zoning—————————
Density and Lot Size Requirements
Gross Density (units/acre)		—————————Refer to underlying zoning—————————
Net Density (units/acre)		—————————Refer to underlying zoning—————————
Gross FAR		—————————Refer to underlying zoning—————————
Site Area (sf)		—————————Refer to underlying zoning—————————
Lot Size (sf/unit)		—————————Refer to underlying zoning—————————
Lot Requirements
Lot Width		—————————Refer to underlying zoning—————————
Lot Depth		—————————Refer to underlying zoning—————————
Other Requirements
Fences and Screening		See Division 10-50.50
Landscaping		See Division 10-50.60
Lighting		See Division 10-50.70
Parking		See Division 10-50.80
Signs		See Division 10-50.100
End Notes
1.	No point on the structure shall exceed height limit measured from existing or natural grade, excluding chimneys, towers, and similar non-habitable architectural projections.
2.	All structures designed with roof pitches greater than 9:12 (rise:run) may exceed the height limit by one foot.
3.	All structures designed with raised wood floors and non-slab foundations may exceed the height limit by two feet.

(Ord. 2020-11, Amended, 5/5/2020 (Res. 2020-17))

10-40.50.040 AO Zone Additional Requirements

A. Applicability.

1. This zone shall be in addition to and shall overlay all other zones where it is applied so that any parcel of land lying in the AO zone shall also lie in one or more of the other zones provided by this Zoning Code. The effect is to create a new zone that has the characteristics and limitations of both the underlying and the overlying zones.

2. Through the adoption of AO zone requirements, public hearings, and noticing it has become public knowledge (to landowners and prospective landowners) that airport operations should be considered as possibly affecting the use of property within the AO zone.

B. AO Zone – Establishment of Airport Noise Impact Areas and Clear Zone Areas.

1. Airport Noise Impact Areas.

a. Airport noise impact areas shall be established in order to distinguish between the severity of the levels of noise impact so that appropriate uses and acoustical performance standards can be established to mitigate the adverse impacts of aircraft noise to protect the public health, safety, and welfare.

(1) Noise levels shall be classified into noise zones, and the Day-Night Average Sound Level (DNL) classifications shall be used for all noise sources. DNL shall be mathematically symbolized as Ldn.

(2) For the purpose of administering these regulations, there shall be three airport noise impact areas as follows:

(a) AP-1 for areas of Ldn 60-65;

(b) AP-2 for areas of Ldn 65-70; and

b. The only noise impact area shown on the Zoning Map is subsection (B)(1)(a)(2) of this section. Changes of noise impact areas will occur automatically with Airport Master Plan updates.

2. Clear Zone (CZ) Area. For the purposes of administering these regulations, there shall be one Clear Zone (CZ) Area in order to regulate area height limitations.

C. AO Zone Uses and Noise Level Reduction.

1. All uses shall be permitted by right in the underlying zone(s), except as qualified by Table 10-40.50.030.A.

2. All uses shall be permitted by conditional use permit in the underlying zone(s), except as qualified by Table 10-40.50.030.A.

3. Use Limitations and Noise Level Reduction (NLR) Standards. In addition to the use limitations presented for the zone in which an airport noise impact area is located, the following residential use limitations shall apply:

a. Although local conditions may require residential use, it is discouraged in AP-2 and strongly discouraged in AP-3. The absence of viable alternative development options should be determined and an evaluation indicating that a demonstrated community need for residential use would not be met if development were prohibited in these areas should be conducted prior to approvals.

b. Where the City determines that residential uses must be allowed, measures to achieve outdoor to indoor Noise Level Reduction (NLR) of at least 25 dB (AP-2) and 30 dB (AP-3) should be incorporated into building plans and be considered in individual approvals. Normal construction can be expected to provide a NLR of 20 dB, thus the reduction requirements are 5, 10, or 15 dB over standard construction and normally assume mechanical ventilation and closed windows year round. Additional consideration should be given to modifying NLR levels based on peak noise levels.

c. NLR criteria will not eliminate outdoor noise problems. However, building location and site planning, design and use of berms and barriers can help mitigate outdoor noise exposure particularly from ground level sources. Measures that reduce noise at a site should be used wherever practical in preference to measures which only protect interior spaces.

Table 10-40.50.030.A

Land Use Compatibility Guidelines
Land Use1	AP-1	AP-2	AP-3
Land Use1	60-65	65-70	70-75
Industrial, Manufacturing, Processing and Wholesaling	Yes	Yes	Yes2
Ranching, Forestry, and Animal Keeping	Yes3	Yes3	Yes4
Recreation, Education, and Assembly3	Yes	Yes	25
Residential
Dwelling: Cluster	25	255	No
Dwelling: Single-Family	25	255	No
Dwelling: Multiple-Family (Second floor or above)	25	255	No
Manufactured Home, Park or Subdivision	No	No	No
Retail Trade5	Yes	Yes	Yes4
Services – General5	Yes	Yes	Yes
Hospitals, Nursing Homes	No	No	No
Medical Services	Yes	Yes	25
Governmental	Yes2	Yes2	257
Educational	No	No	No
Cultural	Yes2	Yes2	307
Nature Exhibits	Yes2	Yes2	No7
Public Assembly	Yes	Yes	No
Auditoriums, Concert Halls	Yes	25	30
Outdoor Music Shells, Amphitheaters	Yes2	No	No
Outdoor Sports Arenas	Yes	Yes8	Yes8
Spectator Sports	Yes	Yes8	Yes8
Amusements	Yes	Yes	Yes
Recreation (Including Golf Courses, Riding Stables, Water Recreation)	Yes2	Yes2	256
Resort and Group Camps	Yes2	Yes2	No
Parks	Yes2	Yes2	Yes2
Other Cultural Entertainment and Recreational	Yes7	Yes7	Yes7

End Notes
1 A definition of each listed use type is in Chapter 10-80 (Definitions).
2 Measures to achieve NLR of 25 dB must be incorporated into the design and construction of portions of these buildings where the public is received, office areas, noise sensitive areas, or where the normal noise level is low.
3 These buildings intended for human occupancy require a NLR of 25 dB.
4 Residential buildings require a NLR of 30 dB.
5 Unless the use is listed more specifically in this table.
6 Refer to subsection (C)(3) of this section.
7 The designation of these uses as “compatible” in this area reflects individual Federal Agencies’ consideration of general cost and feasibility factors, as well as past community experiences and program objectives.
8 Land use compatible if special sound reinforcement systems are installed that mitigate indoor sound impacts.

Key
Yes	Land use and related structures compatible.
No	Land use and related structures are not compatible and shall be prohibited.
NLR	Noise Level Reduction. NLR (outdoor to indoor) to be achieved through incorporation of noise.
25 or 30	Land use and related structures generally compatible; measures to achieve NLR of 25 dB, or 30 dB, must be incorporated into design and construction of structure.
257 or 307	Land use generally compatible with NLR; however, measures to achieve an overall reduction do not necessarily solve noise difficulties and additional evaluation is warranted.

D. AO Zone – Pulliam Airport Area Height Limitations.

1. In order to carry out the provisions of this Zoning Code, airport zones and surfaces are established. The airport zones are shown on Figure 10-40.50.030A, Imaginary Surfaces Used to Define Airspace in the Vicinity of Pulliam Airport. An area located in more than one of the airport zones or surfaces shall be considered to be only in the airport zone or surface with the more restrictive height limitation.

2. Except as otherwise provided, no structure shall be constructed or maintained, or tree permitted to grow, within any airport zone or surface in excess of the height limitation established by this subsection. In addition, no structure or obstruction will be permitted that would cause a minimum obstruction clearance altitude, a minimum descent altitude, or a decision height to be raised.

3. Airport zones and surface height limitations are established for Pulliam Airport as presented in Figure 10-40.50.030A. Base elevations for the runway, primary surface, and other appropriate areas shall be in compliance with “Drawings No. 5 and No. 6 for clear zone areas of the Airport Master Plan Update for Pulliam Airport, Flagstaff, Arizona prepared by Coffman Associates, Airport Consultants and dated October 1, 1984, including any subsequent amendments, and data contained in Part 77, Airspace Height Limitation of Plan” (Airport Master Plan clear zone drawings).

Figure 10-40.50.030A

Imaginary Surfaces Used to Define Airspace in the Vicinity of Pulliam Airport