17.78.070 Perimeter landscaping requirements for nonresidential and mixed use development.
A. Perimeter Areas. Notwithstanding other regulations found in this chapter, perimeter areas shall be landscaped with trees, shrubs, and groundcover. The required area of perimeter landscaping shall be at least the depth of the required yard or setback area. The width of the perimeter landscape areas may be modified as provided for in this section in order to group, shape or cluster existing or planted vegetation to create modulating edges along the perimeter of a site or to create internal vegetation islands. In addition, internal vegetation island(s) may be included in the calculation of perimeter areas and shall be located in order to separate and/or juxtapose buildings and/or parking areas and prioritize access points and junctions in internal circulation if the standards below are met. The total square footage of these modified perimeter landscape areas shall be equivalent to the area of the standard required perimeter width identified above.
1. Reductions to the standard perimeter landscape area width are limited as follows:
a. Perimeter landscape area widths may not be reduced to less than one-third of the required yard or setback area of the zone or 10 feet, whichever is greater;
b. Perimeter landscape areas which have been reduced in width shall not run the length of the existing exterior property lines for more than two-thirds of the said property line;
c. Parking and driveways may not encroach into the remaining perimeter landscape areas. However, site access driveways and pedestrian walkways may cut through the remaining perimeter landscape area substantially perpendicular to the property line.
2. All areas used in the calculation of the perimeter landscape area shall be developed as follows:
a. All significant trees as defined in GHMC 17.99.590 shall be retained. These trees can be applied towards all or some of the trees required to be retained by GHMC 17.99.240(D). Retention of other existing vegetation for landscaping is strongly encouraged; however, it must be equal to or better than available nursery stock.
b. If the area does not contain substantial existing canopy, understory, and groundcover vegetation, it shall be enhanced or planted as follows:
i. At least 80 percent of all trees, shrubs, and groundcover shall be from the preferred species list referenced in GHMC 17.78.050.
ii. Perimeter landscaping may include existing landscaping, planted or a combination of both.
iii. Areas to be landscaped shall be covered with live groundcover vegetation which will ultimately cover at least 75 percent of the ground area within three years.
iv. One deciduous tree a minimum of two-inch caliper or one six-foot evergreen tree shall be planted for every 200 square feet of area to be enhanced or planted. Three shrubs which will attain a height of three and one-half feet within three years shall be provided for every 200 square feet of area to be enhanced. The plantings shall be evenly distributed throughout in a natural planting pattern.
v. A minimum of 40 percent of the required trees shall be evergreen trees a minimum of six feet in height at planting.
vi. For properties located within the boundaries of the height overlay district referenced in Chapter 17.62 GHMC, trees shall be of a species with a mature height no taller than the approved building.
c. LID BMPs may be utilized within the perimeter landscape area, and shall count towards the requirements for enhancement or planting. Where LID BMPs are proposed to meet perimeter landscape requirements, these plantings may deviate from the requirements in this section; provided, that the overall landscape area is not reduced.
3. Zone transition buffers required by GHMC 17.99.180 and enhancement corridor landscaping required by GHMC 17.99.160 shall not be reduced or modified through this chapter.
4. All areas used in the calculation of the perimeter landscape area shall be appropriately documented on the approved land use plans, such as site plan or binding site plan.
B. Residential Buffering. Where a development subject to these standards is contiguous to a residential zoning district, the zone transition standards of GHMC 17.99.180 shall be met. Where a nonresidential development abuts a residential development in the same zone, then that required perimeter area shall be landscaped the full width of the setback areas as follows:
1. A solid screen of evergreen trees or shrubs;
2. A solid screen of evergreen trees and shrubs planted on an earthen berm an average of three feet high along its midline;
3. A combination of trees or shrubs and fencing where the amount of fence does not exceed 50 percent of the lineal distance of the side to be buffered as well as other plant materials, planted so that the ground will be covered within three years.
4. LID BMPs may be utilized within residential buffering, and shall count towards the requirements for residential buffering, as long as screening requirements are met.
C. Areas Without Setbacks.
1. In those areas where there is no required front yard setback or where buildings are built to the property line, development subject to this chapter shall provide street trees at an interval of one every 20 feet or planter boxes at the same interval or some combination of trees and boxes, or an alternative.
2. Street trees shall be a minimum caliper of two inches and be a species approved by the city and installed to city standards. Planter boxes shall be maintained by the property owners and shall be of a type approved by the city.
(Ord. 1347 § 50, 2016; Ord. 1086 § 7, 2007; Ord. 975 § 69, 2004; Ord. 710 § 77, 1996; Ord. 573 § 2, 1990).