§ 30-15.5. Landscape design standards.

Landscape plans, as described above, must be prepared by a licensed landscape architect, registered in the State of Illinois, and evaluated and approved based on the following design criteria.

(a)

Scale and Nature of Landscape Material. The scale and nature of landscape materials must be appropriate to the size of the site and related structures.

(b)

Selection of Plant Material. Plant material must be selected for its form, texture, color, pattern of growth and suitability to local conditions. The use of invasive species is prohibited. Invasive species shall be those included in the "Chicago Botanic Garden" list of "Invasive Plants in the Chicago Region."

(c)

Shade Trees. All deciduous shade trees must have a minimum trunk size of four (4) inches in caliper at planting, unless otherwise specified.

(d)

Evergreen Trees. Evergreens trees must have a minimum height of six (6) feet at planting and shall be incorporated into the landscape treatment of a site, particularly in those areas where year-round screening and buffering is required.

(e)

Ornamental Trees. Single stem ornamental trees must have a minimum trunk size of three (3) inches in caliper at planting, unless otherwise specified. Multiple stem ornamental trees must have a minimum height of eight (8) feet at planting, unless otherwise specified.

(f)

Shrubs.

Unless otherwise specified, all large deciduous and evergreen shrubs must have minimum height of three (3) feet at installation, and all small deciduous and evergreen shrubs must have a minimum height of eighteen (18) inches at installation.

Large shrubs are those shrubs that reach five (5) or more feet in height at maturity. Small shrubs are those shrubs that can grow up to five (5) feet in height if left unmaintained, but generally kept at heights of eighteen (18) to thirty (30) inches.

(g)

Softening of Walls and Fences. Plant material must be placed intermittently against long expanses of building walls, fences and other barriers to create a softening effect and to help break up long expanses of blank walls with little architectural detail.

(h)

Planting Beds. Planting beds may be mulched with shredded hardwood, granite mulch, river rock, feather rocks or similar materials. Lava rock is prohibited.

(i)

Irrigation. Landscape design pursuant to the requirements of this Article recognizes the need for irrigation and water conservation. Sprinkler irrigation systems may be required for certain landscaped areas, as determined by a landscape architect. The need for sprinkler irrigation systems will be determined by the type of plant material and the condition/growing medium that they are installed in. All irrigation systems must be designed to minimize the use of water.

(j)

Energy Conservation. Plant material placement should be designed to reduce the energy consumption needs of the development. In addition, landscape designs must take into account and make an effort to implement sustainable design standards, where appropriate.

(1)

Deciduous trees should be placed on the south and west sides of buildings to provide shade from the summer sun.

(2)

Evergreens and other plant materials should be concentrated on the north and west sides of buildings to dissipate the effect of winter winds.

(k)

Species Diversity. Diversity among required plant material is required not only for visual interest, but to reduce the risk of losing a large population of plants due to disease. Table 15-1: Diversity Requirements indicates the percentage of diversity required based on the total quantity of species being used. For instance, if a development requires forty-five (45) shade trees, no more than eighteen (18) trees nor less than five (5) trees can be of one (1) species, and there must be a minimum of five (5) different species within the forty-five (45) trees.

VILLAGE OF WILMETTE TABLE 15-1: DIVERSITY REQUIREMENTS
TOTAL NUMBER OF PLANTS PER PLANT TYPE	DIVERSITY REQUIREMENTS		MINIMUM NUMBER OF SPECIES
	MAXIMUM OF ANY SPECIES	MINIMUM OF ANY SPECIES
1-4	100%	Not Applicable	1
5-10	60%	40%	2
11-15	45%	20%	3
16-75	40%	10%	5
76-500	25%	5%	8
500-1,000	30%	5%	10
1,000+	15%	4%	15

 

(l)

Berming. Earthen berms and existing topographic features may be incorporated into the landscape treatment of a site where there is sufficient space and, in particular, when berms and existing topographic features can be combined with plant material to facilitate effective screening. Minimum unretained berm side slopes must be maintained at no less than a 4:1 ratio to prevent erosion and be properly and safely maintained. Retained slopes may be implemented with the appropriate terracing necessary to reduce the need for safety railing. Berming is subject to approval of the Village Engineer.

(Code 1993, § 20-15.5)