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Desert Character Overlay Zoning District |
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Terry Newton
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One of the activities sponsored by the North Sonoran Collaborative members to help facilitate planning efforts in the north sonoran deserts of Phoenix was a design charrette which examined both the natural and manmade character of these areas. Recommendations from this charrette were included in a subsequent general plan amendment, which called for the development of several zoning overlay districts to implement specific design standards unique to different parts of northeast Phoenix. This paper discusses the development of one of these zoning district overlays.
During the North Sonoran Land Use Charrette process it became apparent that lifestyle choices in the east portion of Desert View Tri-Villages possessed specific qualitative and quantitative characteristics different from the city as a whole. In response to residents of the area and further study, the North Land Use Plan (Plan) distinguished three character areas. These were identified as the Desert Preserve, Rural Desert, and Suburban Desert Character Areas. The Desert Preserve Character Area concept is to provide a transition between areas earmarked for preservation and more intensely developed areas. To address the high interest in an equestrian lifestyle, the Rural Desert Character Area will maintain an existing lifestyle that has been eroded in the past by more suburban development. With that in mind, an area was identified for more intense suburban development and labeled the Suburban Desert Character Area.
In addition to identifying the three Desert Character Areas, the Plan stated three implementation tools aimed at preserving the desert character throughout all development in the northeast area of the city. In addition to the General Plan Amendment which established a cap on residential densities and the goal set leading to the Sonoran Preserve, the Plan called for development of zoning overlay districts for the three identified Desert Character Areas.
The process for developing the three overlay ordinances is unlike any the city has undertaken in the past. Typically, city staff draft an ordinance which is then reviewed by Village Planning Committees plus other citizen committees as necessary for the ordinance. However, development of the draft Desert Character Overlay Zoning District ordinance is accomplished through a subcommittee of the Desert View Village Planning Committee plus two members of the development community and a member of the city's Design Review Standards Committee (DRSC). Rather than requiring that the subcommittee begin from scratch, Planning Department staff prepare a draft overlay ordinance for the subcommittee members to review, comment on, and revise. When necessary the staff will prepare alternatives of specific concepts so that differing perspectives and ideas are made available to the subcommittee.
The subcommittee then makes their recommendation to the full Desert View Village Planning Committee (Committee). Upon the full Committee's endorsement, the ordinance is reviewed by the DRSC as well as other City Departments. The results of this review are brought back to the original subcommittee. Areas of differences are identified and a joint meeting between the subcommittee and DRSC takes place with the goal of achieving consensus between the two groups before moving on to the formal hearing process with the Planning Commission and City Council.
Under the umbrella of the Desert Character Overlay Zoning Districts, each of the three Character Areas is being carried forward independently through the process. By proceeding in this way delays may be avoided if one of the three overlay districts becomes problematic. So far, the Desert Preserve Character Area has been the only one to be developed. Currently at the consensus building phase, it will soon be taken through the formal hearing process.
The Overlay is further divided into two subdistricts due to different residential densities identified for the area on the General Plan Map. Subdistrict A encompasses the area approximately one mile on both sides of the Cave Creek Wash from Carefree Highway on the north to the Dynamite Road alignment identified on the General Plan and Street Classification Maps to the south. Subdistrict B takes in the remaining area between the Cave Creek Wash and Cave Creek Road south to the Cave Buttes Recreational Area exclusive of areas already developed.
Much of the area identified by Subdistricts A and B is included in the Arizona Preserve Initiative (API) application which is currently being pursued by the city. Of the approximately 5,000 acres identified as Subdistrict A, only 900 acres are outside of the API area. Subdistrict B consists of approximately 1,700 acres with 1,500 acres falling outside of the API area. Assuming the API area as currently identified successfully becomes a preserve, approximately 2,400 acres in Subdistricts A and B would remain for possible development. This is the area addressed by this Overlay.
The overriding purpose of the Overlay is to guide development that will blend with the undisturbed desert rather than dominate it. Residential density for Subdistrict A is capped at 1.2 dwelling units per acre (du/ac). This area is characterized by numerous undisturbed wash tributaries to the Cave Creek Wash and pristine Sonoran Desert vegetation. It is the intent of the Overlay in Subdistrict A to provide regulatory guidelines for compatible development which will provide a transition from the API land to more developed areas along Cave Creek Road.
Subdistrict A is strictly limited to large lot residential development with a minimum lot size of 35,000 square feet. Development of the lots will be based on use of building envelopes with area outside of the envelope maintained in an undisturbed natural state. Areas that experienced prior disturbance are addressed by guidelines allowing revegetation.
Subdistrict B provides a range of densities from 2-5 du/ac. With a requirement that 50 percent of any parcel be maintained undisturbed desert, it is envisioned that true cluster development will be the predominant development style in Subdistrict B. Allowances are made to allow attached residential product with a range of heights to enhance the potential for successful cluster development.
Access points to the API land will be identified and coordinated with the city's Parks, Recreation and Library Department. Provisions are also made for allowing limited commercial uses relating to API access points and the recreational aspect of the API land.
For both Subdistricts, a list of items of intent focuses on maintenance and enjoyment of the Sonoran Desert that is so special to area residents and visitors. The intent of the Overlay focuses on conservation of:
The Overlay addresses a number of items currently not addressed elsewhere by city ordinance or policy, setting new standards and criteria for development. The more universally applicable elements include the use of a site analysis for the siting of developable areas, establishment of criteria for the conservation of wash corridors, clear definition of the use of building or construction envelopes, building height in the context of the desert vegetation, and residential cluster development. Regulations and design guidelines work together to provide development that will be compatible within the context of the Sonoran Desert.
The site analysis will be used as a tool to determine areas that should be retained in an undisturbed state. At the time of rezoning or developing the property the developer will provide current aerial photos with substantial data provided on overlays so that the site can be evaluated by city staff and the developer. Information required includes two-foot land contours, wash corridors, preliminary hydrological data, significant stands of vegetation, specimen plants, 100-year floodplain boundary, archeological data, and adjacent trail locations. Using this information, the developer then identifies potential view corridors, street alignments and development areas. This method ensures greater awareness and involvement by city staff, the developer and consultants at the front end of the process as they become intimately familiar with the site.
Development of wash criteria was of major importance at the inception of the Overlay. Minimum criteria had been developed and executed in the past in the form of rezoning stipulations. In some cases the preservation intent was successful while not so in others. This history of wash preservation provided the basis for the criteria developed. Four categories of wash corridors are established. Regional Wash Corridors are picturesque and carry flows of 750 cubic feet per second (cfs) or greater. Designation as a drainage/vegetation tract is required at the greater of the 100-year storm boundary or 50 feet from the top-of-bank.
Primary, Secondary and Minor Washes make up the other three wash categories. A Primary Wash carries flows of 50-749 cfs during the 100-year storm. Designation as a drainage/vegetation tract is required along this type of wash at the 100-year storm boundary or at an average 50 feet from top-of-bank with a minimum 25-foot required, whichever is greater.
The Secondary Wash is characterized by flow from 10-50 cfs during the 100-year storm without a requirement to be set aside as a separate drainage/vegetation tract. However, setbacks for any structures, including fences, is to be an average of 25 feet with a minimum of 10 feet from the top-of-bank.
Minor Washes carry flows less than 10 cfs during the 100-year storm event. Flexibility is incorporated into the requirements for this classification of wash, essentially stating that if significant vegetation is fed by the wash it is to be maintained. If there is no vegetation served by the wash, it may be removed or rerouted.
Building/construction envelopes are used for all residential large lot development in both Subdistricts A and B. All improvements are to be located within the building envelope which comprises 30 percent of the lot or 20,000 square feet, whichever is less. Building setbacks apply to the building envelope placement not specifically any structures. The location of the building envelope is determined through the site analysis and more specific landscape inventory at the time the lot is developed. Area outside of the building envelope is to remain as permanent undisturbed open space (Figure 1).
Guidelines developed for the large lot residential development focus on maintaining a low profile, disappearing into the desert as much as possible. Building heights are limited to 22-feet from natural grade. This reflect much of the development that has occurred in the past in the desert. Houses typically were low one-story, blending with the varying heights of desert trees, and were strategically sited to avoid significant desert vegetation (Figure 2).
Commercial development in Subdistrict B follows many of the same guidelines as the residential, including building height and use of the site analysis. Additional regulations and guidelines have been developed to more adequately address this type of development. Issues addressed include where they may be located, combining uses into one site, lighting, signage, construction envelopes, setbacks for the construction envelope. The goal here is to allow commercial uses related to recreational uses of the API.
The original General Plan document for the area, adopted in 1987, identified some general guidelines for development which included a concept for residential clusters. Some residential cluster development has occurred in recent years, but it has not met the standard set by that original concept. Development of the regulations and guidelines for Subdistrict B presents the opportunity to more carefully define the type of cluster originally envisioned. Through regulations allowing attached residential product, a range of building heights, and requirements for 50 percent open space, the original vision for residential cluster is more likely (Figure 3)
Development of the Desert Character Overlay Zoning Districts is an ambitious undertaking by the Desert View Village Planning Committee and city staff. Many of the regulations and design guidelines could have application in other areas of the city and set a new standard for the city's approach to development in natural desert areas of the city. The impact remains to be seen with citizens and staff hopeful of a positive outcome.
Terry Newton
Planning Department
City of Phoenix
Email: tnewton@ci.phoenix.az.us