Chapter 19.25
Tree Retention and Landscaping

19.25.010    User Guide

19.25.020    Purpose.

19.25.030    Applicability.

19.25.040    Landscaping Categories.

19.25.050    Landscaping – Types and description.

19.25.060    Landscaping – Street frontages.

19.25.070    Landscaping – Surface parking areas.

19.25.080    Landscaping – General requirements.

19.25.090    Landscaping – Alternative options.

19.25.100    Landscaping – Irrigation.

19.25.110    Landscaping – Installation.

19.25.120    Significant trees – Retention required.

19.25.130    Significant trees – Retention plan.

19.25.140    Significant trees – Incentives for retention.

19.25.150    Significant trees – Protection.

19.25.160    Significant trees – Replacement.

19.25.170    Maintenance.

19.25.180    Bonds/security.

19.25.010 User Guide.

Chapter 19.15 of this Code containing the use zone charts assign a landscaping category to each use in each zone. This category is either “A”, “B”, “C”, “D” “E” or “F”. This Chapter contains the specific requirements that pertain to each category. This Chapter also establishes certain minimum requirements for all uses, and minimum requirements for landscaping of parking lots and retention of existing trees. [Ord. 529, 2009, Ord. 293 § 1, 2000]

19.25.020 Purpose.

The purpose of this chapter is to provide minimum standards for tree retention and landscaping to foster a healthy and attractive community; to maintain a positive community image; to improve the aesthetic quality of the built environment; to enhance quality of life; to protect and enhance property values; to promote retention and protection of existing vegetation; to reduce the impacts of development on drainage systems and natural habitats; to absorb wind and noise; to enhance air quality; to increase compatibility between different land uses; and to increase privacy for and within residential zones by:

1. Providing visual relief from large expanses of parking areas and reduction of perceived building scale;

2. Providing physical separation between residential and nonresidential areas;

3. Providing visual screens and barriers as a transition between differing land uses;

4. Retaining existing vegetation and significant trees by incorporating them into the site design; and

5. Providing increased areas of permeable surfaces to allow for:

A. Infiltration of surface water into ground water resources;

B. Reduction in the quantity of storm water discharge; and

C. Improvement in the quality of storm water discharge. [Ord. 293 § 1, 2000]

19.25.030 Applicability.

This Chapter applies to all new development and to existing development with non-conforming landscaping that is required to comply based on BMC 19.55.035. In the event of a conflict or overlap between landscaping standards in this Code, the most stringent requirements shall apply, as determined by the Director. [Ord. 293 § 1, 2000]

19.25.040 Landscaping Categories.

1. The use zone charts in BMC 19.15 establish a landscaping category for each use in each zone. Table 19.25.040-1 indicates the requirements that must be met for each landscape category. If different landscape categories apply to a site, the category that provides for the most landscaping shall apply. [Ord. 529, 2009, Ord. 441 § 12, 2005]

 

Table 19.25.040-1 

Landscape Category

Along Property Line Abutting a Public Right-of-Way (Except a Freeway or Alley)

Along Property Line Abutting a Freeway*

Along All Other Property Lines (Except Along an Alley)

Along Building Facade Greater Than 35’ High or 50’ Wide

Surface Parking Area Landscaping Required? (see BMC 19.25.070)

A

None

None

None

None

No

B

10’ wide Type III

10’ wide Type II

None, except in a transition area (see BMC 19.17.015)

5’ wide Type IV

Yes

C

10’ wide Type III

10’ wide Type II

None, except in a transition area (see BMC 19.17.015)

5’ wide Type IV

Yes

D

15’ wide Type I

10’ wide Type I

10’ wide Type II, except when abutting an I zone, then none

5’ wide Type IV

Yes

E

See BMC 19.47 and 19.49 for landscaping requirements in the DC and SPA-1 zones. The only sections of BMC 19.25 that apply to the DC and SPA-1 zones are: BMC 19.25.080, 19.25.100, 19.25.110, 19.25.170 and 19.25.180.

F**

25’ wide, Type II (along 8th Ave. So. or Des Moines Memorial Dr.); otherwise, 15’ wide, Type III

None

50’ wide Type I (along northern perimeter of the AI zone); otherwise, 10’ wide Type III

5’ wide Type IV

Yes

*Landscaping abutting a freeway shall be installed within the freeway right-of-way, if permitted by the Washington State Department of Transportation (WSDOT). If such approval is not granted, the landscaping shall be installed on the site.

** The required landscaping width can be reduced up to 50% through use of a landscape berm. Minimum berm width shall be equal to the amount of landscaping width reduction. Minimum berm height shall be 1 foot for each 3 feet of berm width or portion thereof.

The required landscaping width can be reduced up to 75% through use of a solid wall and landscaping. The wall shall use materials (such as wood or concrete) in the same architectural style of the building on the property. Minimum wall height shall be 8 feet. Required landscaping shall be on the outside of the wall.

2. Additional landscaping may be required in the use zone charts in BMC 19.15 and transition standards in BMC 19.17.015. [Ord. 396 § 1, 2003, Ord. 293 § 1, 2000]

19.25.050 Landscaping – Types and description.

The four types of landscaping are described and applied as follows:

1. Type I Landscaping.

A. Type I landscaping is a “full screen” that functions as a visual barrier.

B. Type I landscaping shall consist of:

i. A mix of primarily evergreen trees and shrubs placed to form a continuous screen;

ii. At least 70 percent evergreen trees;

iii. Evergreen trees spaced no more than 25 feet on center;

iv. Deciduous trees spaced no more than 30 feet on center;

v. Evergreen shrubs spaced no more than four feet apart; and

vi. Groundcover pursuant to BMC 19.25.070;

2. Type II Landscaping.

A. Type II landscaping is a “filtered screen” that functions as a visual separator.

B. Type II landscaping shall consist of:

i. A mix of evergreen and deciduous trees and shrubs spaced to create a filtered screen;

ii. At least 50 percent deciduous trees and at least 30 percent evergreen trees;

iii. Evergreen trees spaced no more than 25 feet on center;

iv. Deciduous trees spaced no more than 30 feet on center;

v. Shrubs spaced no more than five feet apart; and

vi. Groundcover pursuant to BMC 19.25.070;

3. Type III Landscaping.

A. Type III landscaping is a “see-through screen” that functions as a partial visual separator to soften the appearance of parking areas and building elevations.

B. Type III landscaping shall consist of:

i. A mix of evergreen and deciduous trees spaced to create a continuous canopy;

ii. At least 70 percent deciduous trees;

iii. Evergreen trees spaced no more than 25 feet on center;

iv. Deciduous trees spaced no more than 30 feet on center;

v. Shrubs, that do not exceed a height of four feet, spaced no more than four feet apart; and

vi. Groundcover pursuant to BMC 19.25.070;

C. Type III landscaping areas may contain bioretention facilities where feasible in accordance with BMC Title 13. Where a bioretention facility is proposed to meet all or part of the Type III landscaping area:

i. The bioretention facility shall be landscaped in accordance with BMC Title 13; and

ii. The total Type III landscaping areas on the site shall be planted with at least 90% of the total number of required trees as calculated above.

4. Type IV Landscaping.

A. Type IV landscaping is “parking area landscaping” and “building facade landscaping” that provides shade and visual relief while maintaining clear sight lines within parking areas;

B. Type IV landscaping shall consist of:

i. Canopy-type deciduous trees spaced no more than 30 feet on center, or evergreen trees spaced no more than 25 feet on-center. At least 70 percent of the trees shall be deciduous.

ii. Shrubs that do not exceed a height of four feet;

iii. Plantings contained in planting islands or strips having an area of at least 75 square feet and with a narrow dimension of no less than four feet;

iv. Groundcover pursuant to BMC 19.25.090.

C. Type IV landscaping areas may contain bioretention facilities where feasible in accordance with BMC Title 13. Where a bioretention facility is proposed to meet all or part of the Type IV landscaping area:

i. The bioretention facility shall be landscaped in accordance with BMC Title 13; and

ii. The total Type IV landscaping areas on the site shall be planted with 100% of the total number of required trees as calculated above. [Ord. 659 § 10, 2016; Ord. 293 § 1, 2000]

19.25.060 Landscaping – Street frontages.

Perimeter landscaping along street frontages shall be provided as follows:

1. For single detached subdivisions:

A. Trees shall be planted at the rate of one tree for every:

i. Fifty feet of frontage along a neighborhood collector street; and

ii. Forty feet of frontage along an arterial street.

B. The trees shall be:

i. Located within the right-of-way if permitted by the custodial state or local agency;

ii. No more than 20 feet from the right-of-way line when located within a lot;

iii. Maintained by the adjacent landowner unless part of a city maintenance program; and

iv. A species approved by the city.

C. The trees may be spaced at irregular intervals in order to accommodate sight distance requirements for driveways and intersections.

D. Mature and healthy native trees retained within the right-of-way or no more than 20 feet from the right-of-way line within a lot may substitute for the required street trees at a one-to-one ratio and may be spaced at irregular intervals. [Ord. 659 § 11, 2016; Ord. 293 § 1, 2000]

19.25.070 Landscaping – Surface parking areas.

1. Where feasible in accordance with BMC Title 13, perimeter and interior landscaping areas shall contain bioretention facilities to manage on-site stormwater runoff. A conceptual illustration is shown in Figure 19.25.070-1.

Figure 19.25.070-1

2. Perimeter Landscaping. A minimum 5’ wide Type IV landscape strip shall be provided on private property along the perimeter of a parking area. The width of the landscape strip shall be increased to 7’ if vehicle overhangs into the landscape strip are allowed. Where bioretention is used, the facility shall be landscaped in accordance with BMC Title 13.

3. Interior Landscaping. The following requirements apply to any surface parking area with 10 or more parking stalls. The interior landscape requirement is in addition to the perimeter landscape area required in BMC 19.25.070.2, and the landscaping required by BMC 19.25.040.

A. Uses requiring landscape category B shall provide interior planting areas at the rate of 20 square feet per parking stall;

B. Uses requiring landscape category C, D or F shall provide interior planting areas at a rate of:

i. Twenty square feet per parking stall when 10 to 30 parking stalls are provided; and

ii. Twenty-five square feet per parking stall when 31 or more parking stalls are provided;

C. Each interior planting area shall contain at least 75 square feet, with a narrow dimension of no less than four feet (six feet if vehicles are allowed to overhang into the landscaped area);

D. Evergreen or canopy-type deciduous trees shall be provided and distributed throughout the parking area at a rate of:

i. One tree for every 10 parking stalls for a use requiring landscape category C, D or F; or

ii. One tree for every five parking stalls for a use requiring landscape category B.

E. Groundcover shall be provided pursuant to BMC 19.25.080.

F. Landscaping islands shall be provided at the ends of each row of parking, except ends of rows that abut required perimeter landscaping.

G. The maximum distance between any parking stall and required interior parking area landscaping shall be no more than 65 feet.

H. Where bioretention is used to meet the interior landscaping requirement, the facility shall be landscaped in accordance with BMC Title 13 and the total interior landscaping areas on the site shall achieve at least 90% of the total number of trees required as calculated in 19.25.070(3)(D). [Ord. 659 § 12, 2016; Ord. 620 § 1, 2016; Ord. 293 § 1, 2000]

19.25.080 Landscaping – General requirements.

1. A landscaping and irrigation plan shall be submitted for review and approval by the Director. Written requirements for the landscaping and irrigation plan shall be established by the Director. The landscaping and irrigation plan shall be prepared by a Washington State registered landscape architect, Washington Certified Nurseryman/Landscaper, or other qualified landscape designer as authorized by the Director. The irrigation plan may be prepared by a certified irrigation designer.

2. New landscaping materials shall include species native to the Pacific Northwest or non-native noninvasive species that have adapted to the climatic conditions of the coastal region of the Pacific Northwest in the following minimum amounts:

A. Seventy-five percent of groundcover and shrubs, and

B. Fifty percent of trees;

3. At least 60 percent of new landscaping materials shall consist of drought-tolerant species, except where site conditions within the required landscape areas assure adequate moisture for growth;

4. With approval of the Director, species and spacing requirements may be relaxed when existing native vegetation augments new plantings to meet the standards of this chapter;

5. Deciduous trees shall have a caliper of at least 1.75 inches at the time of planting. The caliper may be averaged, but no individual tree shall have a caliper of less than 1.5 inches;

6. Evergreen trees shall be at least six feet in height measured from treetop to the ground at the time of planting;

7. When the width of any landscape strip is 20 feet or greater, the required trees shall be staggered in two or more rows;

8. Unless recommended by a Certified Arborist, no tree defined as a prohibited tree in BMC 19.10.408 shall be planted.

9. Shrubs shall be:

A. Two-gallon size at time of planting in Type II, III and IV landscaping,

B. At least 24 inches in height at the time of planting for Type I landscaping, and

C. Maintained at a height not exceeding four feet when located in Type III or IV landscaping;

10. Groundcovers shall be planted and spaced to result in total coverage of the required landscape area within three years as follows:

A. Four-inch pots at 18 inches on center, or

B. One-gallon or greater sized containers at 24 inches on center;

11. Turf grass may be used as groundcover only in Type III and IV landscape areas provided that the grass area:

A. Constitutes no more than 30 percent of such landscape areas; and

B. Is at least five feet wide at the smallest dimension;

12. Turf grass and groundcover areas shall contain at least two inches of composted organic material at finish grade;

13. All fences shall be placed on the inward side of any required perimeter landscaping;

14. Berms shall not exceed a slope of two horizontal feet to one vertical foot (2:1);

15. Existing soils shall be augmented as follows:

A. For sites subject to drainage review in accordance with BMC Title 13, soil amendments shall follow the standards for restoring the soil moisture holding capacity of BMC Title 13, or

B. For sites not subject to drainage review in accordance with BMC Title 13, amend existing soils with a two-inch layer of fully composted organic material rototilled a minimum of six inches deep;

16. Landscape areas shall be covered with mulch to minimize evaporation as follows:

A. For sites subject to drainage review in accordance with BMC Title 13, mulching shall follow the standards for restoring the soil moisture holding capacity of BMC Title 13, or

B. For sites not subject to drainage review in accordance with BMC Title 13, a minimum two-inch layer of mulch shall consist of materials such as yard waste, sawdust and/or manure that is fully composted;

17. Drought-tolerant and nondrought-tolerant species shall be grouped separately and be served by separate irrigation systems, zones or controls;

18. Permanent cast in place concrete curbs or structural barriers shall be provided to protect landscape areas from damage by vehicles. [Ord. 648 § 1, 2017; Ord. 659 § 13, 2016; Ord. 293 § 1, 2000]

19.25.090 Landscaping – Alternative options.

The following alternative landscape options may be allowed only if they accomplish equal or better levels of screening and are subject to Director approval:

1. The width of perimeter landscaping required by BMC 19.25.040 or BMC 19.25.070 may be reduced up to 25 percent along any portion where:

A. A development retains an additional 10 percent of significant trees or an additional 10 significant trees per acre on-site (above the requirements of BMC 19.25.120(3) and (4)), whichever is greater; or

B. Berms at least three feet in height or architectural barriers at least six feet in height (consistent with the style and materials of the building(s) on site) are incorporated into the landscape design; and

C. The landscape materials that would have been planted in the perimeter landscape area are planted along the street facing facade of the building(s) on the site. These landscape materials are in addition to the required building facade landscaping in BMC 19.25.040.

2. The landscaping requirements of BMC 19.25.040 or BMC 19.25.070 may be modified when:

A. Existing conditions on or adjacent to the site, such as significant topographic differences, vegetation, structures or utilities would render application of this chapter ineffective or result in scenic view obstruction; or

B. The landscape materials are incorporated elsewhere on-site and the modification would result in comparable or superior landscaping than would result from compliance with the required standard. [Ord. 293 § 1, 2000]

19.25.100 Landscaping – Irrigation.

All plantings shall receive sufficient water to ensure survival as follows:

1. Except for areas of undisturbed existing vegetation or low areas with existing high soil moisture conditions, all landscape areas shall have automatic temporary or permanent irrigation systems as described in this section. The applicant may request and the Director may approve a manual irrigation plan and schedule in lieu of automatic irrigation.

2. Temporary irrigation systems may be removed after 24 months or two growing seasons, whichever occurs first, provided that the plantings are established. Temporary irrigation systems are allowed for:

A. Areas of undisturbed existing vegetation that are being enhanced with additional plantings;

B. Areas where existing site conditions assure adequate soil moisture for growth, only as required to sustain new plantings;

C. Landscape areas consisting of drought-tolerant vegetation.

3. Permanent irrigation systems are required within all other required landscape areas, provided such systems shall be designed by a certified water use auditor and with:

A. Moisture or precipitation sensors;

B. Automatic timers set for operation during periods of minimum evaporation and that assure adequate moisture levels;

C. Head-to-head spacing, if sprinkler heads are proposed;

D. Pressure regulating devices;

E. Backflow prevention devices; and

F. Separate irrigation zones for:

i. Turf and planting beds; and

ii. Other drought-tolerant species. [Ord. 293 § 1, 2000]

19.25.110 Landscaping – Installation.

1. Landscaping shall be installed prior to issuance of a certificate of occupancy for the project or project phase.

2. The time limit for compliance may be extended to allow installation of landscaping during the next appropriate planting season, provided that a bond or other financial guarantee pursuant to BMC 19.25.180 is submitted prior to issuance of a certificate of occupancy. [Ord. 293 § 1, 2000]

19.25.120 Significant trees – Retention required.

Significant trees shall be retained as follows:

1. All significant trees on an undeveloped lot shall be retained. Tree removal or land clearing on an undeveloped lot for the purpose of future development is prohibited unless a land use permit is approved by the City.

2. Landscape category A: Thirty percent (30%) of the significant trees located on the site, excluding critical areas or their buffers.

3. Landscape category B: Ten percent of the significant trees located on the site, excluding critical areas or their buffers.

4. Landscape categories C, D and F: Five percent of the significant trees located on the site, excluding critical areas or their buffers.

5. If significant trees were previously located in a closed, forested situation, an adequate area of smaller trees shall be retained or replaced on the fringe of such significant trees;

6. A grouping of three or more existing trees with canopies that touch or overlap, may be substituted for each required significant tree, provided each tree has a diameter of at least three inches when measured four feet above grade;

7. Except as provided in BMC 19.25.120.8, significant trees to be retained shall not include significant trees that, according to a written evaluation prepared by a Certified Arborist, are:

A. Damaged or diseased; or

B. Safety hazards due to potential root, trunk or primary limb failure, or exposure of mature trees which have grown in a closed, forested situation.

8. At the discretion of the Director, damaged or diseased or standing dead trees may be retained and counted toward the significant tree requirement if demonstrated that such trees will provide important wildlife habitat and is not classified as a dangerous tree. [Ord. 293 § 1, 2000]

9. If the formula for determining the number of significant trees to be retained results in a fraction, the number of significant trees to be retained shall be rounded up to the nearest whole number. [Ord. 648 § 1, 2017; Ord. 620 § 1, 2016; Ord. 484 § 1, 2008]

19.25.130 Significant trees – Retention plan.

The applicant shall submit a tree retention plan concurrent with a land use review application, grading permit application, building permit application, preliminary subdivision application or short subdivision application, whichever is reviewed and approved first. The Director shall compile and maintain a database of significant trees based upon the submitted and approved tree retention plans. The tree retention plan shall consist of:

1. A tree survey that identifies the location, size and species of all significant trees on a site. The tree survey may be conducted by a method that locates individual significant trees or by using standard timber cruising methods to reflect general locations, numbers and grouping of significant trees provided that, when using either method, the survey:

A. Shall also show the location and species of each significant tree that is intended to qualify for additional credit pursuant to BMC 19.25.140;

B. Any tree 18 inches or greater diameter for the purpose of establishing wildlife habitat value; and

C. Any tree designated as a Heritage tree.

2. A development plan identifying the significant trees that are proposed to be retained, transplanted or restored. [Ord. 648 § 1, 2017; Ord. 293 § 1, 2000]

19.25.140 Significant trees – Incentives for retention.

Each significant tree that is retained may be credited as two trees for complying with the retention requirements of BMC 19.25.120, provided it meets one or more of the following criteria:

1. The tree exceeds 60 feet in height, or 24 inches in diameter for evergreen trees or 30 inches for deciduous trees;

2. The tree is located in a grouping of at least five trees with canopies that touch or overlap;

3. The tree provides energy savings through winter wind protection or summer shading as a result of its location relative to buildings;

4. The tree belongs to a unique or unusual species;

5. The tree is located within 25 feet of any critical area or required critical area buffer; and

6. The tree is 18 inches or greater and is identified as providing valuable wildlife habitat. [Ord. 648 § 1, 2017; Ord. 293 § 1, 2000]

19.25.150 Significant trees – Protection.

To provide the best protection for significant trees:

1. No clearing shall be allowed on a site until approval of tree retention and landscape plans;

2. An area of prohibited disturbance, generally corresponding to the dripline of the significant tree shall be protected during construction with a temporary five-foot-high chain link or plastic net fence. The fencing shall be installed prior to issuance of development permits for the site;

3. No impervious surfaces, fill, excavation, or storage of construction materials shall be permitted within the area defined by such fencing;

4. A rock well shall be constructed if the grade level around the tree is to be raised by more than one foot. The inside diameter of the well shall be equal to the diameter of the dripline of the tree;

5. The grade level shall not be lowered within the larger of the two areas defined as follows:

A. The dripline of the tree(s); or

B. An area around the tree equal to one foot diameter for each inch of tree trunk diameter measured four feet above the ground; and

6. Alternative protection methods may be used if determined by the Director to provide equal or greater tree protection. [Ord. 648 § 1, 2017; Ord. 293 § 1, 2000]

19.25.160 Significant trees – Replacement.

When the required number of significant trees pursuant to BMC 19.25.120 cannot be retained, the required number of significant trees that are removed shall be replaced with: [Ord. 484 § 1, 2008]

1. Transplanted significant trees; or

2. New trees measuring three-inch caliper or more, at a replacement rate of one and one-half (1.5) inches diameter for every one inch diameter of the largest caliper removed significant tree; or

3. New trees measuring less than three-inch caliper at a replacement rate of two inches diameter for every one inch diameter of the largest caliper removed significant tree on a space available basis in conjunction with the site plan. [Ord. 648 § 1, 2017; Ord. 293 § 1, 2000]

19.25.170 Maintenance.

1. All landscaping and significant trees shall be maintained for the life of the project.

2. All landscape materials and significant trees shall be pruned and trimmed as necessary to maintain a healthy growing condition or to prevent primary limb failure;

3. With the exception of dead, diseased or damaged trees specifically retained to provide wildlife habitat, other dead, diseased, damaged or stolen plantings shall be replaced within three months or during the next planting season if the loss does not occur in a planting season; and

4. Landscape areas shall be kept free of trash. [Ord. 648 § 1, 2017; Ord. 293 § 1, 2000]

19.25.180 Bonds/security.

Performance bonds or other appropriate security (including letters of credit and set-aside letters) shall be required for a period of two years after the planting or transplanting of vegetation to insure proper installation, establishment and maintenance. [Ord. 648 § 1, 2017; Ord. 293 § 1, 2000]