Division 13-18-003
Material Selection

Sections:

13-18-003    Material Selection

13-18-003-0001    General Requirements

13-18-003-0002    Irrigation (See Chapter 13-19)

13-18-003-0003    Trees

13-18-003-0003.1    Pre-Approved Trees

13-18-003-0003.2    Prohibited Trees

13-18-003-0004    Shrubs

13-18-003-0004.1    Pre-Approved Shrubs

13-18-003-0005    Ground Cover

13-18-003-0005.1    Pre-Approved Ground Cover

13-18-003-0006    Landscape Materials

13-18-003-0006.1    Mulch

13-18-003-0006.2    Pre-Approved Mulch

13-18-003-0006.3    Root Barrier

13-18-003-0006.4    Pre-Emergent Weed Control

13-18-003-0006.5    Weed Barrier

13-18-003-0006.6    Tree Wrap

13-18-003-0006.7    Planting Soils

13-18-003-0006.8    Landscape Fabric

13-18-003-0007    Furnishings

13-18-003 Material Selection

See Table 13-18-003-01.

Table 13-18-003-01

Material Selection 

Symbol Scale @ 2/3 Maturity

Genus and Species

Common Name

Qty.

Planting Size

Estimated Mature Size Height x Width

Design Spacing O.C.

 

Overstory/Canopy Trees

 

 

Fraxinus pennsylvanica

Green Ash

12

2.5" Cal.

65' x 40'

35'

 

Populus tremuloides

Quaking Aspen

25

2.5" Cal. Multi Stem

28' x 18'

24'

 

Ornamental Trees

 

 

Malus sargentii

Sargent Crabapple

30

1.5" Cal.

10' x 16'

14'

 

Prunus padus

Common Birdcherry

15

1.5" Cal.

24' x 20'

18'

 

Evergreen Trees

 

 

Pinus ponderosa

Ponderosa Pine

5

6' B&B

80' x 30'

30'

 

Shrubs

 

 

Potentilla fruticosa ‘Gold Drop’

Gold Drop Bush Cinquefoil

200

2 Gallon

2' x 2'

2'

 

Pinus mugo mughus

Dwf. Mugho Pine

50

3 Gallon

2.5' x 3'

2.5'

 

Ground Covers and Perennials

 

 

Vinca minor

Periwinkle

300

3" Pot

Ground Cover

1'

(Ord. 2017-22, Rep&ReEn, 07/05/2017)

13-18-003-0001 General Requirements

A list of pre-approved trees, shrubs, and ground cover is provided in the zoning code found in Title 10.

Selection and use of native and drought tolerant plant species is preferred. All plant species shall be cottonless, nonfruiting, and, except for ground cover, minimally seeding.

Plant material shall be true to name, variety and size and shall comply with the applicable provisions of the most recent edition of the American Standard for Nursery Stock (ANSI Z60.1).

A.    Application. Plant material shall be of the quantity, genus, species, variety and size specified. If the specified plant material is not obtainable, submit a statement of nonavailability together with a proposal for use of equivalent material. Substitutions require prior approval from the City of Flagstaff representative.

Trees are allowed only in medians and parkways that have a minimum width of five (5) feet. In retrofit situations, the minimum median and parkway width shall be four (4) feet and tree selection shall be submitted for prior review and approval by the City Engineer or duly appointed designee.

Shrubs, perennials and ground covers are allowed only in medians and parkways that have a minimum width of two (2) feet.

Medians and parkways less than two (2) feet in width shall be in-filled with approved inert materials. Widths are from back of curb to back of curb.

In lieu of those specified in these standards, landscape materials previously approved by a homeowners’ association or approved by an adopted area/special improvement plan are also allowed. (Ord. 2017-22, Rep&ReEn, 07/05/2017)

13-18-003-0002 Irrigation (See Chapter 13-19)

Irrigation system technical specifications are contained in Chapter 13-19.

A.    Except as follows, all landscaped areas within rights-of-way shall be provided with permanent automatic irrigation systems designed to minimize water usage but provide adequate watering for all plant materials.

1.    Exception. Areas designated as native planting areas, riparian, and similar areas that are designed and planted accordingly may install temporary automatic irrigation systems as required to establish plant materials as determined solely by the City, on a case-by-case basis.

B.    Irrigation systems should be designed to permit turf grass to be irrigated separately from all other planting areas.

1.    Turf irrigation zones should be further separated by water needs for slopes, exposure, and turf-type.

2.    Spraying of walks, decks, patios, driveways, buildings and fences should be avoided.

3.    Normal spray patterns should be confined to mass vegetated areas or root zones of plants.

C.    Irrigation schedules should be set when pedestrians are not likely to be present. Controllers shall be timed to spray at night to reduce conflicts with users and to reduce water consumption. (Ord. 2017-22, Rep&ReEn, 07/05/2017)

13-18-003-0003 Trees

A.    All single trunk trees shall have a minimum two (2) inch caliper and a minimum height of eight (8) feet immediately after planting. Tree heights shall be measured from the top of the root ball to the tip of the highest branch.

B.    All conifer trees shall have a minimum height of six (6) feet measured from the top of the root ball to the tip of the leader.

C.    Multi-trunk trees are not allowed in medians and parkways within rights-of-way. (Ord. 2017-22, Rep&ReEn, 07/05/2017)

13-18-003-0003.1 Pre-Approved Trees

A list of pre-approved trees is provided in the zoning code found in Title 10. (Ord. 2017-22, Rep&ReEn, 07/05/2017)

13-18-003-0003.2 Prohibited Trees

Specifically prohibited for landscape use in rights-of-way are the following plant materials:

Botanical Name

Common Name

Acer negundo

Box Elder

Elaeagnus angustifolia

Russian Olive

Populus acuminate

Lance Leaf Cottonwood

Populus alba

White Poplar

Populus augustfolia

Narrow Leaf Cottonwood

Populus fremontii

Fremont Cottonwood

Populus nigra

Black Poplar

Salix species

Willows

Ulmus parvifolia

Chinese Elm

Ulmus pumila

Siberian Elm

(Ord. 2017-22, Rep&ReEn, 07/05/2017)

13-18-003-0004 Shrubs

Shrubs shall be well rooted container stock and shall have a minimum size of three (3) gallons. (Ord. 2017-22, Rep&ReEn, 07/05/2017)

13-18-003-0004.1 Pre-Approved Shrubs

Shrub species selected from the list of pre-approved shrubs found in Title 10 are acceptable. Other species may be acceptable but are subject to approval by the City Engineer and the Public Works Division. (Ord. 2017-22, Rep&ReEn, 07/05/2017)

13-18-003-0005 Ground Cover

Ground cover (other than turf grass) shall be a minimum of four (4) inch well rooted container stock spaced no more than eight (8) inches on center. Well rooted two and one half (2-1/2) inch container stock may be substituted and spaced no more than six (6) inches on center. Ground cover plants shall show a number of vigorous woody runners or a well developed crown.

A list of pre-approved ground cover is provided in the zoning code found in Title 10. (Ord. 2017-22, Rep&ReEn, 07/05/2017)

13-18-003-0005.1 Pre-Approved Ground Cover

Ground cover species selected from the pre-approved list found in Title 10 are acceptable. Other species may be acceptable but are subject to approval by the City Engineer and the Public Works Division. (Ord. 2017-22, Rep&ReEn, 07/05/2017)

13-18-003-0006 Landscape Materials

13-18-003-0006.1 Mulch

Mulch shall be used in areas where soils have been disturbed as a result of the planting activities and/or where designated on the approved landscape plan. Hydroseeding may be used where designated on the approved landscape plan. (Ord. 2017-22, Rep&ReEn, 07/05/2017)

13-18-003-0006.2 Pre-Approved Mulch

A.    Wood mulch shall be ground or shredded wood products processed specifically as landscape mulch. Depth of installation shall be two (2) inches minimum and three (3) inches maximum. Prior to mulch installation pre-emergent weed control and a geotextile weed barrier shall be installed.

B.    Rock mulch shall be decomposed granite, landscape rock, river rock, pea gravel, red cinders or black cinders. Red and black cinders shall be a minimum of one-half (1/2) inch in diameter. Depth of installation shall be two (2) inches minimum and three (3) inches maximum. Prior to mulch installation pre-emergent weed control and a geotextile weed barrier shall be installed. (Ord. 2017-22, Rep&ReEn, 07/05/2017)

13-18-003-0006.3 Root Barrier

A.    Root barriers shall be one (1) continuous piece, a minimum of twenty four (24) inches in depth and installed such that the top is even with the top of adjacent pavement.

B.    Root barriers shall be installed parallel and adjacent to curb and gutter, sidewalks or similar permanent surfaces. The root barrier shall extend four (4) feet each way of the tree center. Root barriers shall be used in parkways with a width of eight (8) feet or less. (Ord. 2017-22, Rep&ReEn, 07/05/2017)

13-18-003-0006.4 Pre-Emergent Weed Control

Pre-emergent weed control shall be Dacthal or equal and shall be used prior to the installation of wood and rock mulch materials. Installation shall be in accordance with the manufacturer’s written instructions. (Ord. 2017-22, Rep&ReEn, 07/05/2017)

13-18-003-0006.5 Weed Barrier

Weed barrier shall be a synthetic, nonwoven, water permeable geotextile. Manufacturer’s technical information and a nominal four (4) inch square sample shall be submitted for City of Flagstaff’s prior approval. (Ord. 2017-22, Rep&ReEn, 07/05/2017)

13-18-003-0006.6 Tree Wrap

Tree wrap shall be heavy, crinkle crepe paper, four (4) to ten (10) inches wide and manufactured specifically as tree wrap. (Ord. 2017-22, Rep&ReEn, 07/05/2017)

13-18-003-0006.7 Planting Soils

A.    General Planting Soil. Soil excavated from the planting pit shall generally be deemed acceptable as backfill material for planting unless specifically designated by the owner as unacceptable.

1.    If quantity of usable soil is inadequate, the contractor shall supply planting soil, which shall be clean, fertile and friable with four percent (4%) to twenty-five percent (25%) organic matter.

2.    Imported planting material shall require prior approval by the owner.

3.    Mechanically ground or pulverized soil is not acceptable.

B.    Structural Soil Mix.

1.    Street trees planted within a tree grate shall be planted in topsoil backfill using a structural soil system between tree pits beneath pavement areas.

2.    Structural Soil Mix. The structural soil mix shall be a uniformly blended, three (3) part mix consisting of a 5:1 ratio of crushed stone to clay loam, by weight, with three-hundredths percent (0.03%) hydrogel added. Total moisture at mixing shall be ten percent (10%) in accordance with AASHTO T-99 (optimum moisture).

The stone shall be clean, angular, gap graded, three-quarters (3/4) to one and one-half (1-1/2) inch crushed stone with no fines. Volcanic rock is explicitly excluded.

The clay loam shall consist of less than five percent (5%) gravel, twenty-five percent (25%) to thirty percent (30%) sand, twenty percent (20%) to forty percent (40%) silt and twenty-five percent (25%) to forty percent (40%) clay with two percent (2%) to five percent (5%) organic matter in accordance with the USDA soil classification system.

Hydrogel shall be A1000C Hydro-Gel as manufactured by Finn Corporation, Fairfield, Ohio, or an approved equal. (Ord. 2017-22, Rep&ReEn, 07/05/2017)

13-18-003-0006.8 Landscape Fabric

A weed inhibiting material shall be placed underneath all areas to be mulched prior to installation. Color should be grey or black at four (4) ounce weight. Plastic products are prohibited. (Ord. 2017-22, Rep&ReEn, 07/05/2017)

13-18-003-0007 Furnishings

All furnishings shall be acquired from a recognized manufacturer that produces products for use in public places and to the greatest extent possible, be of the same make and model as existing street furniture elsewhere within the City. (Ord. 2017-22, Rep&ReEn, 07/05/2017)