20D.40.35 Landscape Design Standards.

20D.40.35-010 Purpose.

The purpose of this section is to establish criteria for planting design, parking lot landscaping, and tree preservation. (Ord. 1993)

20D.40.35-020 Planting Design.

(1)    Intent.

(a)    Planting design is an integral part of the overall site and community design and should complement the architecture, other site elements and the visual appearance of the neighborhood, as well as the northwest environment. The landscape plan should help reduce impacts to and create a transition to adjacent natural features, such as sensitive areas and shorelines. The landscape plan should be based on a well-defined concept addressing criteria for function, design, horticulture, maintenance, and irrigation.

(b)    The planting design should be a composition of plant materials that creates an appropriate visual character, such as stylized, formal, informal, or natural. The design should include a suitable combination of trees, shrubs, groundcover plants, vines, lawns and herbaceous material, including native and Northwest-adapted plants. The number, size and arrangement should be carefully selected to balance color, texture, form, line, proportion, and scale in both the horizontal and vertical plane.

(2)    Design Criteria.

(a)    Retention and Enhancement of Existing Vegetation. Preserve as much native noninvasive vegetation as possible, particularly adjacent to buffers of sensitive areas and shorelines. Replant developed areas with stands of nondwarf evergreens in natural and random patterns where possible.

(b)    Usable Open Space and Public View Corridors. Provide space onsite for active and/or passive recreational purposes. When located in an identified public view corridor, this open space may also provide views through a development to important features, such as the Lake Sammamish, Sammamish River, and the River Valley; Bear Creek; or panoramic mountain views.

(c)    Buffer. Provide separation between incompatible adjacent land uses or activities, and reduce the impact of wind, lighting, and perception of noise.

Figure 51: Planting Design Criteria (2)(a) and (2)(c) of this section.

This stand of significant trees was retained. It serves as a buffer between the adjacent uses.

(d)    Transition. Provide plantings that effectively accommodate a change in design between adjacent sites, within a site, and from native vegetation areas. To lessen impacts and provide transitions to natural areas, use native plants as much as possible adjacent to the buffers of critical areas and shorelines. Design foundation plantings to create an effective change from public to private space and from the vertical to horizontal plane at building edges.

(e)    Mitigation of Adverse Visual Impacts. Provide planting to soften the visual impact of less desirable development and/or structures, such as large blank walls, dumpster areas, service areas, and large areas of pavement.

(f)    Definition or Emphasis. Use planting to highlight significant site features and to define site use areas and circulation corridors without interfering with the use of such areas. Examples include site and building entrances, pedestrian walkways, and focal points, such as gathering areas or plazas.

Figure 52: Planting Design Criteria (2)(f) of this section.

Distinctive landscaping highlights building entry and enhances the corner.

(g)    Safety. Use planting landscaping which minimizes disruption of sight lines along pathways.

(h)    Water Conservation. Plants and techniques that reduce water consumption are encouraged.

(i)    Design. Plants should be selected and arranged according to the following design criteria:

(i)    Unity. Arrange plants in an orderly composition creating an overall unified and balanced design which is the sum of the parts, visually, and provides a sense of order, balance and harmony.

(ii)    Variety. Select a variety of plants providing interest, accent and contrast, using as many native species as possible.

(iii)    Consistency. Develop a planting design compatible with and conforming to the overall project design concept and adjoining properties.

(iv)    Appropriateness. Develop a planting design concept that is compatible with the architectural character, land use, and environment. Select plants with an awareness of their growth requirements, tolerances, ultimate size, preferences for soil, climate and sun exposure, and negative impacts.

(v)    Density. Provide adequate plant quantity, size, and spacing to fulfill the functional and design objectives within the stipulated time. (Ord. 2486; Ord. 2340; Ord. 1993)

20D.40.35-030 Parking Lot Landscaping.

(1)    Intent.

(a)    To improve the aesthetic appearance of parking lots;

(b)    To reduce the summertime heat and glare buildup within and adjacent to parking lots;

(c)    To provide landscaped areas within parking areas in addition to landscape buffers around the perimeter of parking lots;

(d)    To provide screening and break up the expanse of paved areas.

(2)    Design Criteria.

(a)    Cluster interior parking lot landscaping when possible to conserve significant portions of existing tree cover as an amenity to the site. (See also Chapter 20D.80 RCDG, Landscaping and Tree Protection.)

(b)    Disperse interior parking lot landscaping throughout a parking lot when no significant existing vegetation exists.

(c)    Shade trees should be used to shade parking lots and driveways to reduce summer heat loads.

(d)    Provide landscaped areas within parking areas in addition to landscape buffers around the perimeter of parking lots to effectively screen vehicles.

(e)    All parking lots should be planted with sufficient trees so that within 10 years 50 percent of the surface area of the lot is shaded. Additionally, parking lots should be screened from streets by nonbermed landscaped treatments.

Figure 53: Parking Lot Landscaping Criteria (2)(d) of this section.

Perimeter landscaping screens the vehicles.

(Ord. 1993)

20D.40.35-040 Tree Retention.

(1)    Intent.

(a)    To preserve and enhance the unique character that trees provide to the area;

(b)    To preserve and protect stands of mature trees and retain substantial natural vegetation in accordance with the regulations for tree preservation;

(c)    To aid in the stabilization of soil by preventing erosion;

(d)    To reduce storm water runoff;

(e)    To provide a visual buffer and screen against traffic and noise;

(f)    To lessen impacts of development on adjacent sensitive areas and shorelines.

(2)    Design Criteria.

(a)    Where there is a stand of significant trees, treat the stand as a natural feature and employ techniques described in RCDG 20D.80.20, Tree Protection.

(b)    Mature trees, stands of trees, and trees and their understory adjacent to a critical area or shoreline buffer should be protected wherever possible.

Figure 54: Tree Retention Criteria (2)(a) of this section.

Site plans can be modified to save significant trees and stands of trees.

(Ord. 2486; Ord. 1993)