18.73.030   Performance standards.
   A.   Scope. This section provides general standards for bufferyards, landscape designs and landscape plans. Specific design references, standards and plant lists in the form of a landscape design manual are hereby adopted to ensure compliance with this chapter. The landscape design manual may be amended by resolution of the board after a noticed public hearing. The planning director may approve minor changes to the landscape design manual. Landscape reference materials and plant lists are available at the planning and development services department.
   B.   General Standards.
      1.   Landscape designs shall be in harmony with the environmental context of the development site. Preservation of native, on-site vegetation shall be a primary objective of site planning for development. Specimen plants shall be given particular consideration for retention on site. Property owners shall comply with the provisions of Arizona Revised Statutes, Section 3-904;
      2.   Wherever the undisturbed natural desert landscape cannot be preserved, or has been disturbed through past land use and is no longer representative of the native habitat, landscape design and construction shall promote the use of transplanted, on-site desert plants, container plants, seeded desert plants and inorganic groundcovers. This standard shall be particularly emphasized on all landscaped areas abutting public rights-of-way, scenic routes and landscaping having high public visibility;
      3.   The environmental zone design principle of appropriate plant selection and placement, based on the function, water requirement and most suitable environmental exposure of the plant materials, shall be used in all proposals. The mini-oasis design provision may be permitted when proposed water-intensive planting designs are found by the planning director to substantially meet criteria found in the landscape design manual;
      4.   Turf applications over ten acres, except as required by the Pima County department of natural resources, parks and Recreation, including parks and recreational facilities, cemeteries and school grounds shall be irrigated with reclaimed water, effluent, or CAP water. Golf course design and its use of turf within Pima County is regulated by the Golf Course zone (Chapter 18.59);
      5.   Plants shall be selected from the approved plant lists within the Landscape Design Manual. Requests for changes in the plant lists may be made to the planning director, who shall review the request and enter all approved changes to the plant list addendum which shall be available from the planning department;
      6.   Trees and shrubs.
         a.   Trees shall be at least five gallons in size, or of comparable height if bare-rooted, at planting time,
         b.   Shrubs shall be at least one gallon in size at planting time,
         c.   Trees and shrubs shall be planted so that at maturity they do not interfere with service lines, traffic sight lines and the property rights of adjacent property owners, and
         d.   Trees planted near public sidewalks or curbs shall be provided with suitable root diverters to minimize heaving of those improvements;
      7.   Groundcovers.
         a.   When inorganic groundcovers are used, they shall be in combination with live plants and not exceed two-thirds of the total area of applied groundcovers,
         b.   Turf use, except as required by Pima County Department of Natural Resources, Parks and Recreation, shall be for functional use only, not to exceed an area that is equal to fifteen percent of the required landscaped area, and shall be located, when used, on the development site:
            1)   To mitigate glare and reduce heat near buildings and their openings, windows and patios,
            2)   To enhance a mini-oasis,
            3)   To enhance a pedestrian entryway,
            4)   In an environmental zone compatible with the context of the landscape and architectural design,
            5)   To conserve water and demonstrate this ethic to the public;
         c.   Unpaved areas in any plant bed, median or tree understory within a planter shall be planted with shrubs, accents or vines, or covered with appropriate organic and inorganic groundcovers;
      8.   Irrigation and water accent features:
         a.   All water use for landscape irrigation and enhancement shall conform to the Arizona Groundwater Code (Title 45, Chapter 2) and the adopted groundwater management plan for the Tucson active management area, except areas located outside of the Tucson active management area, which must adhere to the requirements of this chapter,
         b.   Each introduced planting shall be served by a water-conserving, underground irrigation system that incorporates rain sensors and is capable of seasonal adjustments, unless otherwise approved by the planning director. Stormwater harvesting and drip irrigation are the preferred irrigation methods,
         c.   Required landscape areas shall use a separate reclaimed ready irrigation system to promote the use of effluent to irrigate landscaped and turf areas. A note describing effluent use feasibility shall be included on landscape plans indicating briefly: cost-effectiveness, potential sources and availability,
         d.   Landscape designs shall be integrated with improvement plans for the site and shall make maximum use of site stormwater runoff for irrigation purposes, and
         e.   Water design features that use groundwater or CAP water, such as ponds and fountains, shall not exceed more than fifty square feet in size unless approved by the design review committee with a suitable justification to demonstrate why the water design feature requirements cannot be met within fifty square feet.
      9.   Natural features:
         a.   Earth berms shall be designed to transition to existing grades, shall not exceed a slope of 2:1, and shall be adequately covered with plant material, groundcovers or rip-rap to control erosion,
         b.   Natural drainageways and existing, natural vegetation may be used for screening and amenity landscape credit if approved by the planning director, provided such uses are consistent with the county floodplain management ordinance;
      10.   Streetscape sculpture and furniture: Streetscape bufferyards wider than ten feet may be reduced by ten percent of their required width, for each one hundred linear foot section that includes an, approved public sculpture or furniture piece installed and maintained within the bufferyard. Public sculpture and furniture shall be approved by the design review committee (reference Chapter 18.99), subject to standards contained in the landscape design manual;
      11.   Safety design standards:
         a.   Walls, fences, signs, landscaping and other potential obstructions to view in excess of two feet in height shall be placed in accordance with the requirements of Section 18.77.020;
      12.   Public right-of-way standards:
         a.   Landscaping in publicly owned or controlled areas shall be consistent with the purpose and requirements of this chapter, design requirements as specified in the county development standards code, the department of transporation's subdivision street standards, the scenic routes ordinance and the Pima County landscape design manual;
         b.   A right-of-way use permit and maintenance agreement must be obtained from the Pima County Real Property Division prior to installation of any landscaping within the public right-of-way.
      13.   Plant materials spacing: Plants may be grouped, clustered or unevenly spaced to prevent the creation of an unnatural appearance in the landscape, provided that screening and mitigation of site development from streets and adjoining lots is provided and the design complies with the Landscape Manual.
   C.   Stormwater Harvesting Option.
      1.   Stormwater harvesting in bufferyards. When stormwater harvesting systems meet requirements in Section 18.07.030(S)(2) and cover at least three-quarters of the required bufferyard area:
         a.   The height of walls required in the Landscape Design Manual for Bufferyards A through D only may be reduced to three and one-half feet; and
         b.   The density of canopy trees required in the Landscape Design Manual for all bufferyards may be reduced by fifty percent.
(Ord. 2015-7 § 5 (part), 2015; Ord. 2006-97 § 1 (part), 2006; Ord. 1985-171 § 1 (part), 1985)