17.145.060 Plant material and general planting standards.
(1) Quality. Plant materials used in conformance with the provisions of these standards shall be free of any disease at the time of planting. All plant materials may be examined by the planning department one year from the date of their installation. Any ground cover, shrubs, or trees found to be in a less than acceptable condition will be documented and a written notice for replacement of said material will be sent to the owner, developer, or their agent. If the documented material is not replaced within the time specified, the planning director may abate the same and render a bill covering the cost of such abatement.
(2) Trees.
(a) All plant material designated as “trees” on an approved site plan shall be species that are rated as having an average mature spread of crown of greater than 10 feet in the state of Washington. Immediately upon planting, trees shall be a minimum of seven feet in trunk height and shall have a minimum caliper of two inches measured from a height of four feet above the ground after installation.
(b) Trees of species whose roots are known to cause damage to roadways or other public works shall not be planted closer than 12 feet to any roadway, water line or sewer line. Other varieties may be submitted for approval as a street tree with at least two sources regarding growing. A combination of street trees, planter boxes or other landscaping may be substituted for street trees upon approval by the planning director. Such trees shall be planted using manufactured root barriers or equivalents approved by the public works director.
(c) Trees shall not be placed so as to interfere with site drainage, or where they shall require frequent pruning to avoid interference with power and utility lines.
(d) Tree Species Mix. When more than 10 trees are required to be planted, a mix of species shall be provided. The number of species to be planted shall vary according to the total number of trees required. The minimum number of species to be planted are indicated in the following table. Species shall be planted in proportion to the required mix. This species mix shall not apply to areas of vegetation required to be preserved by law.
|
Required Number of Trees |
Minimum of Species |
|---|---|
|
11 – 20 |
2 |
|
21 – 30 |
3 |
|
31 – 40 |
4 |
|
41 or more |
5 |
(3) Shrubs and Hedges.
(a) Shrubs shall be a minimum of 24 inches in height when measured at the time of planting.
(b) Shrubs shall be planted in all interior and perimeter landscape areas, although are not required for street frontages, except as provided in SMC 17.145.080. Required shrub plantings shall be spaced 18 to 36 inches on center. Spacing of individual plants shall depend on the types of shrubs that are to be installed. Exceptions and/or substitutions from this requirement may be approved by the planning director to promote the use of slow growing or native plant material.
(c) Hedges, where required, shall be planted and maintained so as to establish a continuous, unbroken, solid visual screen within a maximum of two years from the date of installation.
(4) Vines. Vines may be used in conjunction with fences, screens, or walls.
(5) Ground Covers.
(a) All landscape areas, including interior, perimeter, and street frontage planting areas, shall utilize ground cover in between trees and shrubs.
(b) Ground covers used in lieu of grass shall be planted in such a manner as to present a finished appearance and reasonably complete coverage within one year after installation.
(c) Ground cover shall be planted every 18 inches on center. If one-gallon pots are used, ground cover may be planted every 24 inches on center.
(6) Turf Grass. Grass may be used as ground cover where existing or amended soil assure adequate growth. Grass areas may be sodded, plugged, sprigged, or seeded, except that solid sod shall be used in areas subject to erosion. Grasses should be selected that are suitable to the climate, location, and physical conditions of the site so they can be reasonably expected to survive.
(7) Native Plant Materials Selection Criteria. Trees and other vegetation shall be planted in soil and climatic conditions which are appropriate for their growth habits and characteristics. Plants used in landscape design pursuant to this chapter shall, to the greatest extent possible, be:
(a) Appropriate to the conditions in which they are to be planted;
(b) Have noninvasive growth habits;
(c) Encourage low maintenance, a reduction of water consumption, high quality design; and
(d) Otherwise consistent with the intent of these standards.
(8) Irrigation Systems. Temporary irrigation systems are encouraged to be used for any new development in the city as part of a proper maintenance program for landscaped areas. Permanent irrigation systems may be used, but are not encouraged. It is important to ensure that the watering of all plant materials is done in the most efficient manner possible. To this end, it shall be mandatory that where any new development proposes to utilize an irrigation system (either piped or soaker hoses), plans for such a system that shows the location of all lines and sprinkler heads shall be submitted for approval to the public works department.
(9) In instances where healthy plant material exists on a site prior to its development, the planning director may adjust the application of these standards to allow credit for such plant material if, in his or her written opinion, such an adjustment is in keeping with and will preserve the intent of these standards. (Ord. 1110 § 3, 2002; Ord. 1027, 1998; Ord. 929 Ch. 10(K)(3)(c), 1995).