Division 13-18-002
Landscape Design
Sections:
13-18-002-0001 Preface
13-18-002-0002 Nomenclature
13-18-002-0003 General Design Goals
13-18-002-0003.1 Context Sensitive Design
13-18-002-0003.2 Complete Streets
13-18-002-0003.3 Other General Design Goals
13-18-002-0004 Quantitative Landscape Design Parameters
13-18-002-0004.1 Table Notes
13-18-002-0005 Project Metrics
13-18-002-0001 Preface
This division identifies and quantifies desired "landscape design concept" or "theme" for rights-of-way for the City of Flagstaff.
A. The designer must rely on the discipline of landscape architecture and landscape architecture professionals to determine the appropriate landscape concept or theme for rights-of-way.
B. Landscaping is context specific. The contexts through which rights-of-way pass include several spectrums, ranging from very natural areas to very urbanized areas, and through various micro-climates, soil conditions, topography, and many more. The various combinations of these different spectrums make up a broad range of contexts through which rights-of-way pass. (Ord. 2017-22, Rep&ReEn, 07/05/2017)
13-18-002-0002 Nomenclature
For the purposes that transects are used herein, the particular project area need not be a part of a traditional neighborhood design and need not have mapped transects.
As used in Flagstaff, traditional neighborhood design describes the community in six (6) standard transects, described as follows:
T-1 – The most rural, undisturbed, natural land.
T-2 – Rural, but modified lands, including agricultural lands and a range of park lands from primitive open space parks to developed parks, with only agricultural and park serving built elements.
T-3 – The edge areas of a town or city, suburban areas characterized primarily by low density housing with limited land use mixing.
T-4 – An area that is characterized by higher density and a greater mix of land uses, though the residential character is prevalent.
T-5 – Typically a neighborhood center with a yet higher density and a mix of land uses in which the commercial character is dominant.
T-6 – The most urbanized area; downtown Flagstaff.
SD – Finally, industrial districts, gateway sites, and other areas that are not described by transects T-1 through T-6 are classified as "special districts."
Greater detail in the descriptions of transects is provided in Title 10, Flagstaff Zoning Code. (Ord. 2017-22, Rep&ReEn, 07/05/2017)
13-18-002-0003 General Design Goals
13-18-002-0003.1 Context Sensitive Design
In context sensitive landscape design, landscaping occurs within a natural and built environment and specific solutions shall respond in such a way as to be inherently congruent. As a whole, and for the various design elements that make up the whole, proposed work shall be compatible with its context – "context" collectively referring to the significant resources of the property itself, the surrounding properties, and the neighborhood. Work is compatible if it is designed to complement the contexts’ significant visual and physical characteristics, is cohesive and visually unobtrusive in terms of scale, texture, and continuity, and if it maintains the overall patterns of the context. Compatibility utilizes the basic design principles of composition, rhythm, emphasis, transition, simplicity, and balance in the design.
A. Natural Context. Flagstaff, at an elevation of approximately seven thousand (7,000) feet, is at the base of the highest mountains in Arizona. The surrounding terrain generally slopes away, is incised by intermittent drainages, and contains a wide range of vegetation zones, including riparian, semi-arid, and conifer species. The general USDA plant zone is Zone 1, though microclimates may allow for Zone 2 plant materials. Eight (8) local habitats are identified as (1) dry ponderosa pine forest habitat (open woodland); (2) high-elevation cold moist habitat; (3) warm ponderosa pine forest/pinon-juniper woodland; (4) streamside and moist canyon habitat; (5) mid-elevation sunny meadow habitat; (6) chaparral habitat; (7) high desert grassland habitat; and (8) ephemeral streams and seasonal runoff. [See www.thearb.org/]
Soils in the area vary widely in type and character, including coarse and fine grained materials and expansive clays. Highly permeable cinder soils and fractured rocks allow precipitation to percolate. Flagstaff and the surrounding area are underlain by a complex series of volcanic and sedimentary rocks. The rock sequence that underlies the volcanic formations comprises a series of consolidated sedimentary formations laid down prior to tectonic disturbance and subsequent volcanic activity.
Groundwater is generally found around five thousand five hundred (5,500) feet in depth. In some areas, groundwater perched on volcanic formations is close to the surface and supplies seeps and springs supporting very diverse ecosystems. Flagstaff receives enough precipitation during an average year to support a significant amount of vegetation - approximately twenty-one (21) inches of precipitation during the year, including an average of eighty-six (86) inches of snow. However, these amounts are quite variable from one (1) year to the next.
Flagstaff enjoys over three hundred (300) days of sunshine per year and low humidity. Weeks can pass in spring and autumn without any rain, whereas the summer monsoon season in July and August brings intense lightning and rainstorms. In the peak of summer, daily high temperatures rarely exceed eighty-five (85) degrees, though winter storms and temperatures can be severe. With the last killing frost generally in May, sometimes as late as June, Flagstaff has a ninety (90) to one hundred twenty (120) day growing season.
Fire is a natural and frequent occurrence with roughly six hundred (600) ignitions per year.
1. Baseline Design Theme. Preservation of, and compatibility with, Flagstaff’s natural environment is the baseline design theme. Landscape designs shall maximize the amount of land retained in its natural state. Projects shall be designed to preserve and protect native vegetation, particularly existing trees and attractive natural features. New landscaping for rights-of-way shall seek the restoration of the natural environment disturbed by construction.
The baseline theme may vary depending on location and use. For example, landscaping along a forest road (T-1) may have areas where there are trees and native grasses and other areas where just native grasses are appropriate. On such a road, the use of native species only, and more natural spacing, is appropriate.
B. Urban Context. As rights-of-way contexts become more urban in character, the less appropriate it is to mimic the natural environment. For the various transects in between a forest road (T-1) and downtown (T-6), the immediate context and the degree of urbanity guide the design of landscaping toward a natural or urban theme.
1. Gateways, more structured, ornamental, formal, and dense plantings are appropriate. They serve as an exclamation point, highlighting an entrance or major feature and welcoming passersby.
a. Neighborhoods may have a gateway area, serving a smaller scale area within the City.
b. Notably, gateways are relatively small sites and a particular landscape project area may be sufficiently large so as to include a gateway area as well as other contexts.
2. Evaluation of the project context shall include determining if the project area is, or contains, a gateway area.
The designer and the project review staff should establish the degree of urbanity, or transect, and shall establish the appropriate landscaping design measures. The determination shall encompass the character of the neighborhood as a whole, including the forestation and development on the adjacent private property; and, to the greatest extent possible, shall consider the proposed or desired future conditions over existing conditions. This determination measures how much deviation from the baseline design theme is appropriate or desirable. (Ord. 2017-22, Rep&ReEn, 07/05/2017)
13-18-002-0003.2 Complete Streets
Modern transportation design recognizes that streets are a part of public street space and serve various transportation modes, users, and uses (complete streets), and that an ideal street is in fact a place and not simply for vehicle conveyance. Landscaping is a critical part of complete streets and landscaping design solutions for all rights-of-way shall always include the purpose of placemaking and the design of complete streets.
A. Street Trees. Street trees planted in a parkway separating the travel lanes from the pedestrian way is an important landscape element. Walkable streets provide a sense of safety for pedestrians, sun and wind control, aesthetics, traffic calming and much more. Street trees are required for complete streets and are always required for landscaping of rights-of-way.
1. Sometimes under unique circumstances such as retrofits, street trees may be located behind the sidewalk.
2. Street trees shall provide the shading, visual enhancement, and continuity for the streetscape. A continuous street edge with trees normally placed midway between curb and walk is required.
a. Any existing specimen or mature street tree shall remain and shall be considered a planted tree for purposes of meeting density requirements.
b. Tree placement should consider visibility of signage and storefronts, as well as public views, and shall be located offset from building entrances.
3. As a general rule, for transects T-4, T-5, and T-6, evenly spaced street trees are required.
a. A "skyline" or "canopy tree" function in the design should be included, though occasional ornamental trees are appropriate.
b. At the urban transect T-4, such plantings should be more rural in character and at the T-6 end, trees should be planted in boxed out planters with iron tree grates.
4. In rural transects T-1 and T-2, the design of street trees, types, density, and placement should help restore the natural environment.
a. Through design solutions, trees will both function as a typical street tree and as a part of the natural context.
5. For urban areas in suburban transect T-3 that are more urban, the urban solutions in transects T-4, T-5, and T-6 should be employed.
6. For natural areas, natural street tree designs in transects T-1 and T-2 are appropriate.
a. An area in the forest with lot sizes measured in acres may not need evenly spaced "street trees."
b. An area with small lots, especially where most of the forest has been removed, the evenly spaced planting of street trees may be appropriate.
A list of pre-approved trees is provided in the zoning code found in Title 10. (Ord. 2017-22, Rep&ReEn, 07/05/2017)
13-18-002-0003.3 Other General Design Goals
A. Grading.
1. Rights-of-way projects shall conclude with ground forms that are natural in character. Contour lines shall be organic and curvilinear and without the sharp corners commonly associated with the machine grading necessary for infrastructure improvements.
a. Landscape designs may, and if appropriate shall, use finish grading to achieve this result.
2. Swales and similar drainage courses shall be designed as gently rolling, free form ground sculpture with a natural appearance. Where space and hydrological needs permit, they should be broad shallow channels with established vegetation designed to promote infiltration and trap pollutants. Dissipation structures, if any, shall be designed to be as natural in appearance as possible such as the use of rock lining.
3. Where appropriate and where space permits, earthen berms shall be incorporated into finish grading. Berms are usually two (2) to six (6) feet high and shall be designed as gently rolling, free form ground sculpture with an undulating top. The ridge of berms should be rounded (i.e., neither flat nor meeting at the peak). Continuous planting along the ridgeline of berms should be avoided.
B. Maintenance. Landscape designs should balance the value of landscaping and the obligations for maintenance.
C. Other Built Elements. Landscape projects should incorporate elements other than plants that create a comfortable, safe, and attractive public experience.
1. Benches, receptacles, bike racks, newspaper racks, water fountains, lighting and public art are good examples and should be identified in the scope of work.
a. The design should evaluate opportunities during the course of developing specific landscape solutions.
2. In designing elements in response to the scope of work or an apparent opportunity, calibration to the transect is appropriate.
a. In considering the selection of such elements, boulders may be used in rural transects T-1 and T-2 to accent the landscape design, while plazas or benches are appropriate in urban transects T-4, T-5, and T-6.
b. In considering basic layouts, pedestrian ways (sidewalks) can be organic in rural transects T-1 and T-2 and have a formal character in urban transects T‑4, T-5, and T-6.
D. Plant Placement.
1. For the natural environment, plant placement shall be informal groupings of trees, shrubs and ground covers.
a. Plantings on slopes shall have varied heights.
2. More urbanized areas warrant more structured plant placement. In more urbanized areas, more formal, unobstructed visibility to building entrances, key architectural features, signage, and public spaces are to be maintained.
a. Use of landscaping to define, accent, or soften adjacent buildings is appropriate.
E. Screening. As rights-of-way landscaping designs are developed, landscaping shall screen adjacent parking and service areas, and exterior transformers, utility pads, cable television, telephone boxes, and similar objects to the greatest extent possible.
F. Water Usage. Landscape designs should balance the value of landscaping and the value of responsible water usage. Selection, density, and placement of plants relative to available water supplies need to be considered in the design concept. The selection of native and drought tolerant species is encouraged. Use of reclaimed water for irrigation substantially addresses this balance.
Plantings in transects T-1, T-2, and some of T-3 may not need irrigation after the establishment period. During that period, temporary systems may serve the need. In transects T-4, T-5, and T-6, ornamental, formal plantings will need more water.
G. Winter Conditions. Trees should be selected and placed so as to minimize winter icing on roads, walkways, and other paving. Placement relative to winter sun angles, spacing, type as deciduous or conifer, and material density should be considered. (Ord. 2017-22, Rep&ReEn, 07/05/2017)
13-18-002-0004 Quantitative Landscape Design Parameters
Table 13-18-002-01 - Quantitative Landscape Design Parameters provides guidance regarding landscape design in terms of plant types, densities, and placement in the context of transects.
A list of pre-approved trees, shrubs, and ground cover is provided in the zoning code found in Title 10. (Ord. 2017-22, Rep&ReEn, 07/05/2017)
13-18-002-0004.1 Table Notes
As Practical – The placement of evenly spaced trees is noted in the table as "As Practical" recognizing that some deviation in spacing may be necessary to accommodate utilities, driveways, and other similar objects in the right-of-way. The quantity of trees shall still be determined in accordance with the density column of the table, and any surplus trees due to a necessary deviation in spacing, shall be planted elsewhere in the right-of-way or if need be, elsewhere within the project.
Boulders – For transects T-1, T-2, and T-3, to encourage the use of boulders in landscape designs, up to fifteen percent (15%) of shrubs indicated in the table may be replaced by native boulders on an "area covered" basis. One-third (1/3) of the boulder’s height should be buried.
Clusters – The natural forest density is not monolithic and varies from meadows to clusters of trees and shrubs. In emulating the natural surrounds in accordance with the table, the table indicates when clustering is expected to be appropriate.
Coverage at Maturity – The area covered by the plant material when it has reached maturity, based on industry standards for size at maturity, compared to the planting area in which the plant material is located.
Existing Plants – Existing plant materials that are protected and that survive construction count toward the density requirements of the table.
Match Surrounds – This term is used to indicate that new landscaping should match the existing context. Context refers to the general area of a project or even sub-areas of a project (see this division).
Median – As used in the table, a median is the area between vehicular travel lanes.
Parkway – As used in the table, a parkway is the area between the curb and the sidewalk.
Road Segment – As used in the table, a road segment is generally a block, but could be a group of blocks that as a whole make up a single logical design element. A boulevard is an example of such an element.
Species Appropriate Spacing – Spacing based on industry standards. (Ord. 2017-22, Rep&ReEn, 07/05/2017)
13-18-002-0005 Project Metrics
To serve as a baseline metric for specific landscaping projects, Table 13-18-002-01, Quantitative Landscape Design Parameters, shall be considered baseline (minimum) requirements and any deviation from such parameters shall be at the sole discretion of the City of Flagstaff as determined by the project review staff.
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Trees |
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|---|---|---|---|
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|
Type |
Density |
Placement |
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T-1: The most rural, undisturbed, natural land. |
|||
|
Parkways, Medians, and Other Areas |
Match Surrounds |
Match Surrounds including Clusters (Max. 100 per acre) |
Match Surrounds including Clusters |
|
T-2: Rural, but modified lands. |
|||
|
Parkways, Medians, and Other Areas |
Match Surrounds |
per T-1 and Add 15% (Max. 100 per acre) |
Match Surrounds Clusters |
|
T-3: The edge areas of a town or city, suburban areas - Large lot subdivisions and substantially forested lands. |
|||
|
Parkways, Medians, and Other Areas |
Match Surrounds |
per T-1 and Add 30% (Max. 100 per acre) |
Match Surrounds Clusters |
|
T-3: The edge areas of a town or city, suburban areas - Small lot subdivisions and/or substantially denuded lands. |
|||
|
Parkways |
Max. Two Types per Road Segment |
(1) per 45 FT |
45 FT O.C. (As Practical) |
|
Medians |
Max. Two Types per Road Segment |
(1) per 45 FT |
45 FT O.C. (As Practical) |
|
Other Areas |
Match Surrounds |
per T-1 and Add 30% (Max. 100 per acre) |
Match Surrounds including Clusters |
|
T-4: Higher density mixed-use area - residential prevalent. |
|||
|
Parkways |
Max. Three Types per Road Segment |
(1) per 45 FT |
45 FT O.C. (As Practical) |
|
Medians |
Max. Three Types per Road Segment |
(1) per 45 FT |
45 FT O.C. (As Practical) |
|
Other Areas |
Match Surrounds |
per T-1 Add 15% (Max. 100 per acre) |
Match Surrounds Clusters |
|
T-5: Higher density mixed-use area - Commercial prevalent. |
|||
|
Parkways, Tree Wells |
Max. Two Types per Road Segment |
(1) per 45 FT |
45 FT O.C. (As Practical) |
|
Medians |
Max. Two Types per Road Segment |
(1) per 45 FT |
45 FT O.C (As Practical) |
|
Other Areas |
Should not occur in urban area; where occurs, see Special District. |
||
|
T-6: Downtown Flagstaff |
|||
|
Parkways, Tree Wells |
One Type per Road Segment |
(1) per 45 FT |
45 FT O.C. (As Practical) |
|
Medians |
One Type per Road Segment |
(1) per 45 FT |
45 FT O.C. (As Practical) |
|
Other Areas |
Should not occur in urban area; where occurs, see Special District. |
||
|
Special Districts |
|||
|
Parkways |
Max. Three Types per Road Segment |
(1) per 45 FT |
45 FT O.C. (As Practical) |
|
Medians |
Max. Three Types per Road Segment |
(1) per 45 FT |
45 FT O.C. (As Practical) |
|
Other Areas |
Match Surrounds |
per T-1 and Add 30% (Max. 100 per acre) |
Match Surrounds |
|
|
Shrubs |
||
|---|---|---|---|
|
|
Type |
Density |
Placement |
|
T-1: The most rural, undisturbed, natural land. |
|||
|
Parkways, Medians, and Other Areas |
Match Surrounds |
Match Surrounds including Clusters |
Match Surrounds including Clusters |
|
T-2: Rural, but modified lands. |
|||
|
Parkways, Medians, and Other Areas |
Match Surrounds |
Match Surrounds including Clusters |
Match Surrounds including Clusters |
|
T-3: The edge areas of a town or city, suburban areas - Large lot subdivisions and substantially forested lands. |
|||
|
Parkways, Medians, and Other Areas |
Match Surrounds |
Match Surrounds including Clusters |
Match Surrounds including Clusters |
|
T-3: The edge areas of a town or city, suburban areas - Small lot subdivisions and/or substantially denuded lands. |
|||
|
Parkways |
Where Occurs – per Medians |
None or per Medians |
Where Occurs - per Medians |
|
Medians |
(1) per (50) Plants to Max. (5) Types Min. 15% per Type |
Min. 25% Coverage at Maturity less Ground Cover |
Species Appropriate Spacing with Diamond Pattern |
|
Other Areas |
Match Surrounds |
per T-1 and Add 30%. |
Match Surrounds including Clusters |
|
T-4: Higher density mixed-use area - residential prevalent. |
|||
|
Parkways |
Where Occurs – per Medians |
None or per Medians |
Where Occurs – per Medians |
|
Medians |
(1) per (50) Plants to Max. (5) Types Min. 15% per Type |
Min. 50% Coverage at Maturity less Ground Cover |
Species Appropriate Spacing with Diamond Pattern |
|
Other Areas |
Match Surrounds |
per T-1 and Add 15%. |
Match Surrounds including Clusters |
|
T-5: Higher density mixed-use area - Commercial prevalent. |
|||
|
Parkways, Tree Wells |
None |
None |
None |
|
Medians |
(1) per (50) Plants to Max. (5) Types Min. 15% per Type |
Min. 75% Coverage at Maturity less Ground Cover |
Species Appropriate Spacing with Diamond Pattern |
|
Other Areas |
Should not occur in urban area; where occurs, see Special District. |
||
|
T-6: Downtown Flagstaff |
|||
|
Parkways, Tree Wells |
None |
None |
None |
|
Medians |
(1) per (50) Plants to Max. (5) Types Min. 15% per Type |
Min. 75% Coverage at Maturity less Ground Cover |
Species Appropriate Spacing with Diamond Pattern |
|
Other Areas |
Should not occur in urban area; where occurs, see Special District. |
||
|
T-6: Special Districts |
|||
|
Parkways |
Where Occurs – per Medians |
None or per Medians |
Where Occurs – per Medians |
|
Medians |
(1) per (50) Plants to Max. (5) Types Min. 15% per Type |
Min. 25% Coverage at Maturity less Ground Cover |
Species Appropriate Spacing with Diamond Pattern |
|
Other Areas |
Match Surrounds |
per T-1 and Add 30%. |
Match Surrounds |
|
|
Living Ground Cover |
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|---|---|---|---|
|
Type |
Density |
Placement |
|
|
T-1: The most rural, undisturbed, natural land. |
|||
|
Parkways, Medians, and Other Areas |
Native Grass and Wildflower Seed Mix |
100% Coverage of Disturbed Areas |
Hydroseed |
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T-2: Rural, but modified lands. |
|||
|
Parkways, Medians, and Other Areas |
Native Grass and Wildflower Seed Mix |
100% Coverage of Disturbed Areas |
Hydroseed |
|
T-3: The edge areas of a town or city, suburban areas - Large lot subdivisions and substantially forested lands. |
|||
|
Parkways, Medians, and Other Areas |
Native Grass and Wildflower Seed Mix |
100% Coverage of Disturbed Areas |
Hydroseed |
|
T-3: The edge areas of a town or city, suburban areas - Small lot subdivisions and/or substantially denuded lands. |
|||
|
+Parkways |
Where Occurs - per Medians |
None or per Medians |
Where Occurs – per Medians |
|
Medians |
(1) per (500) Plants to Max. (5) Types Min. 15% per Type |
Min. 25% Coverage at Maturity less Shrubs |
Species Appropriate Spacing with Diamond Pattern |
|
Other Areas |
Native Grass and Wildflower Seed Mix |
100% Coverage of Disturbed Areas |
Hydroseed |
|
T-4: Higher density mixed-use area - residential prevalent. |
|||
|
Parkways |
Where Occurs – per Medians |
None or per Medians |
Where Occurs – Medians |
|
Medians |
(1) per (500) Plants to Max. (5) Types Min. 15% per Type |
Min. 50% Coverage at Maturity less Shrubs |
Species Appropriate Spacing with Diamond Pattern |
|
Other Areas |
Native Grass and Wildflower Seed Mix |
100% Coverage of Disturbed Areas |
Hydroseed |
|
T-5: Higher density mixed-use area - Commercial prevalent. |
|||
|
Parkways, Tree Wells |
per T-4 (Tree Wells per Medians) |
per T-4 (Tree Wells per Medians) |
per T-4 (Tree Wells per Medians) |
|
Medians |
(1) per (500) Plants to Max. (5) Types Min. 15% per Type |
Min. 75% Coverage at Maturity less Shrubs |
Species Appropriate Spacing with Diamond Pattern |
|
Other Areas |
Should not occur in urban area; where occurs, see Special District. |
||
|
T-6: Downtown Flagstaff |
|||
|
Parkways, Tree Wells |
per T-4 (Tree Wells per Medians) |
per T-4 (Tree Wells per Medians) |
per T-4 (Tree Wells per Medians) |
|
Medians |
(1) per (500) Plants to Max. (5) Types Min. 15% per Type |
Min. 75% Coverage at Maturity less Shrubs |
Species Appropriate Spacing with Diamond Pattern |
|
Other Areas |
Should not occur in urban area; where occurs, see Special District. |
||
|
Special Districts |
|||
|
Parkways |
Where Occurs – per Medians |
None or per Medians |
Where Occurs – per Medians |
|
Medians |
(1) per (500) Plants to Max. (5) Types Min. 15% per Type |
Min. 25% Coverage at Maturity less Shrubs |
Species Appropriate Spacing with Diamond Pattern |
|
Other Areas |
Native Grass and Wildflower Seed Mix |
100% Coverage of Disturbed Areas |
Hydroseed |
(Ord. 2017-22, Rep&ReEn, 07/05/2017)