HomeMy WebLinkAboutPlanning 2018-01-25 Item 4 - TMC 18.54 Tree Regulations Update - Attachment A: Draft Revisions to TMC 18.06 Definitions in Strikeout/Unerline FormatTMC 18.06: Revised or New Definitions
Tukwila Tree and Environment Advisory Committee and Planning
Commission Revisions
Note: New text is shown as underlined text; text proposed for deletion
is shown in strikeout. This list of definitions includes existing definitions
as well as proposed new definitions related to trees and landscaping.
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At -Risk Tree
"At -Risk Tree" Imeansla tree that is exposed to potential damage but can be retained during
construction by use of appropriate tree protection measures as prescribed by a Qualified Tree
Professional or by TMC Chapter 18.54.
18.06.125 Caliper
"Caliper" means the American Association of1NurserymersAmericanHortIaccepted standard for
measurement of trunk size of nursery stock. Caliper of the trunk for new trees shall be taken
six€ -inches above the ground for up to and including four -inch caliper size trees and 12 inches
above ground for larger size trees.'
18.06.130 Canopy
"Canopy" means an area encircling the base of a tree, the minimum extent of which is
delineated by a vertical line extending from the outer limit of a tree's branch tips down to the
ground.
18.06.135 CanopylCovetj
"Canopy Cover" means the extent of the canopy for an individual tree, or the cumulative areal
extent of the canopy of all trees on a the site. When a tree trunk straddles a property line, 50%
of the canopy shall be counted towards each property. The canopy coverage of immature trees
and newly planted trees is determined using the projected canopy areas in the City's
Recommended Tree List.
18.06-140 Certified Arborist:
"Certified Arborist"-, see "Qualified Tree Professional" means an arborist certified by the
International Socicty of Arboriculture or National Arborist Association►.
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Commented [CL1]: This is a new definition from Lake
Forest Park with revisions proposed by staff.
Commented [CL2]: Current definition with revisions from
Kirkland definition.
Commented [CL3]: "AmericanHort" is the professional
association formerly known as the American Nursery and
Landscape Association, which merged with the Association
of Horticultural Professionals to become AmericanHort.
Commented [CL4]: This definition applies to nursery
stock for new trees being planted and is distinguished from
measuring diameter of existing trees. Existing trees are
measured 4.5 feet from the ground, which is also referred
to as "Diameter at Breast Height — DBH".
Commented [CL5]: Current definition with additions from
Lake Forest Park.
TMC 18.06: Revised or New Definitions
Tukwila Tree and Environment Advisory Committee and Planning
Commission Revisions
18.06.145 learingl
"Clearing" means removal or causing to be removed, through either direct or indirect actions,
any vegetation from a site. Actions considered to be clearing include, but are not limited to,
causing irreversible damage to roots or trunks; poisoning; destroying the structural integrity;
and/or any filling, excavation, grading, or trenching in the root area of a tree which has the
potential to cause irreversible damage to the tree.
Critical Root lZone
"Critical Root Zone (CRZ)" means the area surrounding a tree at a distance from the trunk,
which is equal to one foot for every inch of trunk diameter measured at four and one-half feet
from grade (DBH) or otherwise determined by a qualified professional (example: a 24 -inch
diameter tree would have a CRZ of 24 feet. The total protection zone, including trunk, would be
48 feet in diameter).
Crown
"Crown" means the area of a tree containing leaf- or needle -bearing (branches
Dead Treel
"Dead Tree" means a tree with no live crown and no functioning vascular tissue.
18.06.199 Defective 'Tree'
"Defective Tree" means a tree that meets all of the following criteria:
1. A tree with a combination of structural defects and/or disease that makes it subject to a
high probability of failure; and
2. A tree in proximity to moderate to high frequency targets (persons or property that can
be damaged by tree failure); and
3. The hazard condition of the tree cannot be lessened with reasonable and proper
arboricultural practices nor can the target be removed.
Diameter at Breast 'Height' (DBH)
"Diameter at Breast Height (DBH)" means the diameter of existing Trees measured four and
one-half feet above the ground.
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ICommented [CL6]: No change proposed.
Commented [CL7]: Lake Forest Park
We propose using this term rather than "Essential Root
Zone"
ICommented [CL8]: ISA source of definition
ICommented [CL9]: Lake Forest Park.
Commented [CL 10]: This definition was added when the
landscaping code was revised in March, 2017.
lCommented [CL11]: Lake Forest Park
TMC 18.06: Revised or New Definitions
Tukwila Tree and Environment Advisory Committee and Planning
Commission Revisions
IDripline[
"Dripline" means the distance from the tree trunk that is equal to the furthest extent of the
tree's crown or six-foot radius from the trunk of the tree, whichever is greater (this from Lake
Forest Park).
"Essential root zone" means the area located on the ground between the tree trunk and 10 feet
beyond the lanopyl.
Exceptional Tree
"Exceptional Tree" means a tree that is at least I18241 inches in diameter (DBH). For trees with
two stems, if the stems have a combined total diameter of at least 24 inches, the tree shall be
considered an Exceptional Tree. For trees with three or more stems, if the three largest stems
have a combined total diameter of at least 1824 inches, the tree shall be considered an
Exceptional Tree.
18.06.380 Groundcover
"Groundcover" means trees, shrubs and any other plants or natural vegetation which covers or
shades in whole or in part the earth's surface
Hazardous Tree
See "Defective treej'.
Heritage f Tree or Heritage Grove
"Heritage Tree" means a tree, or group of trees comprising a grove, specifically designated by
the City because of historical significance, special character, and/or community benefit.
Invasive Plant and Tree List
"Invasive Plant and Tree List" means the City list of plants and trees that are prohibited from
being planted in landscaped areas subject to an approved landscape plan, and City properties
and rights -of -way -
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Commented [CL12]: From Kirkland and Lake Forest Park
Commented [CL13]: Proposed using the term "Critical
Root Zone" rather than this term.
Commented [CL14]: Size of Exceptional Tree revised by
Committee.
Commented [CL15]: This definition revised when
landscaping code revisions were adopted in March, 2017.
Commented [CL16]: Issaquah
TMC 18.06: Revised or New Definitions
Tukwila Tree and Environment Advisory Committee and Planning
Commission Revisions
Invasive Tree'
"Invasive Tree" means a non-native tree species, which is likely to spread and disrupt the
balance of an eco -system.
Landscape Design Professional
"Landscape Design Professional" means a landscape architect person licensed by the State of
WWashingtonIto engage in thc practice of landscape architecture as defined by RCW 18.98 030 or
..............................
an individual who has graduated from an other accredited landscape design programofessional.
18.06.185 L andscape Architect
"Landscape architect" moans a person licensed by thc State of Washington to engage in the
practice of landscape architecture as defined by RCW 18.96.030.
18.06.490 Landscaping or Landscaped Areas
"Landscaping or Landscaped Areas" means natural vegetation such as trees, shrubs,
groundcover, and other landscape materials arranged in a manner to produce an aesthetic
effect appropriate for the use to which the land is put. Ilnl addition, landscaping or landscaped
areas may also serve as bioswales to reduce storm water runoff, subject to the standards of this
Chapter and TMC Chapter 14.30.
Mulch
"Mulch" means wood chips, bark or other organic material that covers the ground for weed
control and water retention purposes.
18.06.586 Native Vegetation
"Native vegetation" means vegetation with a genetic origin of Western Washington, Northern
Oregon and Southern British Columbia, not including cultivars.
Nuisance Tree
"Nuisance Tree" means a tree that is causing obvious physical damage to structures including
but not limited to sidewalks, curbs, the surfaces of streets, parking lots, or driveways, or
building foundations. Nuisance Tree does not include trees that currently meet the definition
of Hazardous or Defective Tree.
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Commented [AC171: ISA source for definition.
Commented [CL18]: This definition added to reflect new
landscape code and text in TMC 18.52 that identifies those
individuals who may prepare landscape plans for projects.
Commented [CL19]: Propose using "Landscape Design
Professional"
Commented [CL20]: Amended definition to reflect new
landscaping code, which allows bioswales to substitute as
landscaped areas if certain criteria are met.
TMC 18.06: Revised or New Definitions
Tukwila Tree and Environment Advisory Committee and Planning
Commission Revisions
18.06.645 Protected Tree/Protected Vegetation
"Protected tree/Protected Vegetation" means tree or area of understory vegetation identified
on an approved landscape plan to be retained and protected during construction.
18.06.650 Protection Measure
"Protection Measure" means the practice or combination of practices (e.g. construction
barriers, protective fencing, tree wells, etc.) used to control construction or development
activity, where such activity may impact vegetation which is approved for retention in a Tree
CI Bring Permit.
18.06.651 Protective Fencing
"Protective Fencing" means a non -flexible, temporary fence or other structural barrier installed
to prevent permitted clearing or construction activity from adversely affecting vegetation
which is approved for retention required by in- a Tree CI grins Permit or approved landscaping
plan.
Pruning
"Pruning" means the cutting or limbing of tree or shrub branches. Pruning does not include the
removal of any portion of the top of the tree, sometimes referred to as "topping".
Qualified Tree IProfessionall an individual who is a certified professional with academic and
field experience that makes them a recognized expert in urban forestry and tree protection. A
Qualified Tree Professional shall be a member of the International Society of Arboriculture (ISA)
and/or the Association of Consulting Arborists, and shall have specific experience with urban
tree management in the state of Washington. Arborists preparing tree valuations shall have the
necessary training and experience to use and apply the appraisal methodology prescribed in the
most recent edition of the ISA Plant Appraisal Guide.
Risl�:
"Risk" means, in the context of urban forestry and trees, the likelihood of tree failure causing
damage to a Target such as property or persons.
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Commented [CL21]: Current definition, with proposed
revisions.
Commented [CL22]: New definition, primarily from
Portland, with staff additions.
Commented [CL23]: Modified from Lake Forest Park
Commented [CL24]: Modified from Lake Forest Park with
City revisions.
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TMC 18.06: Revised or New Definitions
Tukwila Tree and Environment Advisory Committee and Planning
Commission Revisions
18.06.705 Screening:
"Screening" means a continuous fence and/or evergreen landscaped planting that effectively
conceals the property it encloses.
18.06.775 Significant' Tree
"Significant Tree" means a single -trunked tree (Cottonwood excluded} which is four -4 inches or
more in diameter as measured e . e e - • - • (DBI -1} gra4e or a
multi -trunked tree with a diameter of two -inches or more on any trunk (such as willows or vine
maple).
18.06.776 Significant Tree, Shoreline:
"Significant trcc, shoreline" means a single trunked tree that is 'I inches or more in diameter at
a height of 4 feet above the ground or a multi trunked tree with a diameter of 2 inches or more
such as willows or vinc maple).
18.06.777 Significant Vegetation Removal'
"Significant Vegetation Removal" means the removal or alteration of trees, shrubs, and/or
ground cover by clearing, grading, cutting, burning, chemical means, or other activity that
causes significant ecological impacts to functions provided by such vegetation. The removal of
invasive or noxious weeds does not constitute significant vegetation removal. Tree pruning,
not including tree topping, where it does not affect ecological functions, does not constitute
significant vegetation removal.
Site 'Disturbance':
"Site Disturbance" means any development, construction, or related operation that could alter
the subject property, including, but not limited to, soil compaction including foot traffic, tree or
stump removal, road, driveway or building construction, installation of utilities, or grading.
18.06.785 Solid Planting':
"Solid Planting" mans a planting of evergreen trccs and/or shrubs which will prevent a
through and unobscured penetration of sight or light.
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Commented [CL25]: Revised to reconcile this definition
with the definition for a 'Significant Tree" in the shoreline
jurisdiction.
Commented [CL26]: No changes proposed to this
definition.
Commented [CL27]: New definition — Kirkland.
Commented [C128]: In searching the code, I do not find
the term "Solid Planting" used; TMC 18.52.020 0 defines
"Type Ill -Heavy Perimeter Screening", which is essentially a
solid planting, so this definition is not needed.
TMC 18.06: Revised or New Definitions
Tukwila Tree and Environment Advisory Committee and Planning
Commission Revisions
Street Tree
"Street Tree" means a tree located within the public right-of-way, or easement for street use
granted to the City, provided that, if the trunk of the tree straddles the boundary line of the
public right-of-way and the abutting property, it shall be considered to be on the abutting
propertv.1
Target or Risk f argetl:
"Target or Risk Target" means, as used in the context of urban forestry or trees, people,
property, or activities that could be injured, damaged, or disrupted by a tree.
Tree Risk Assessment
"Tree Risk Assessment" means the systematic process to identify, analyze and evaluate tree
risk, -prepared in accordance with the latest version of the ISA Best Management Practices
Guide by a Qualified Tree Professional.
Tree Risk lAssessorl:
"Tree Risk Assessor" means a Qualified Tree Professional with a Tree Risk Assessment
Qualification, who identifies subject tree(s) and site conditions, evaluates and classifies the
likelihood of failure, estimates the consequences of tree(s) hitting a Target and determines
options for treatment or mitigation.
18.06.845 LTreel
"Tree" means any self-supporting woody plant which at maturity is usually 20 feet or more in.
height and generally has one main trunk, with a potential diameter br ast height of 2 inches or
more characterized by one main trunk, or for certain species, multiple trunks, typically reaching
12-15 feet in height at maturity that is recognized as a Tree in the nursery and arboricultural
industries.
18.06.850 Tree Remov•aiClearing Permit:
"Tree Removal CI wring Permit" means a permit issued by the Director authorizing tree cl aring
removal activities, or work that may impact the Critical Root konel, pursuant to the general
permit provisions of this Title.
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Commented [CL29]: This definition from Kirkland. Street
tree is also defined in TMC 11.04.040 883 as "any trees
located on any street or public right-of-way". It is not
defined in the new TMC 18.52 ordinance.
Commented [CL30]: Modified from Lake Forest Park.
Commented [CL31]: Modified from Lake Forest Park.
Commented [CL321: Current definition with revisions
from Lake Forest Park.
Commented [CL33]: This phrase added by staff to reflect
change in permit title by Advisory Committee and the
various circumstances that may trigger a Tree Permit.
TMC 18.06: Revised or New Definitions
Tukwila Tree and Environment Advisory Committee and Planning
Commission Revisions
Tree IRemovall:
"Tree Removal" means the direct or indirect removal of a tree through actions including, but
not limited to: clearing, cutting, girdling, topping, or causing irreversible damage to roots or
stems, destroying the structural integrity of trees through improper pruning, poisoning, or
filling, excavating, grading, or trenching within the dripline that results in the loss of more than
20 percent of the tree's root system; or the removal through any of these processes of greater
than 50 percent of the live crown of the tree.
Commented [CL34]: New definition from Lake Forest
Park.
fToppinp,I. -( Commented [CL35]: Revised from Portland
"Topping" means the inappropriate pruning practice - - - - used
to reduce tree height by cutting to a predetermined crown limit without regard to tree health
or structural integrity. Topping does not use acceptable pruning practices as described in the
American National Standards Institute (ANSI) "A 300 Pruning Standards" and companion "Best
Management Practices for Tree Pruning" published by the International Society of
Arboriculture, such as crown reduction, utility pruning, or crown cleaning to remove a safety
hazard, dead or diseased material.
18.06.860 Understory Vegetation:
"Understory vegetation" means small trees, shrubs, and groundcover plants, growing beneath
and shaded by the canopy of a significant tree, which affect and are affected by the soil and
hydrology of the area surrounding the significant tree roots.
18.06.910 Vegetation:
"Vegetation" means living trees, shrubs or groundcover plants.
Viable ltreel:
"Viable Tree" means a Significant Tree that a Qualified Tree Professional has determined to be
in good health with a low risk of failure, is relatively Windfirm if isolated or exposed, and is a
species that is suitable for its location and is therefore worthy of long-term retention.
lWindfirml
"Windfirm" means a tree that is healthy and well -rooted and that a Qualified Tree Professional
has evaluated and determined that can withstand normal winter storms or surrounding tree
removal.
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Commented [CL36]: Lake Forest Park
Commented [CL37]: Lake Forest Park