23-106053 - TPP -12-27-2023WASHINGTON FORESTRY CONSULTANTS, INC.
FORESTRY AND VEGETATION MANAGEMENT SPECIALISTS W F C I
O: 360/943-1723
C: 360/561-4407
9136 Yelm Hwy SE
Olympia, WA 98513
URBAN/RURAL FORESTRY • TREE APPRAISAL • TREE RISK ASSESSMENT
RIGHT-OF-WAYS • VEGETATION MANAGEMENT • FOREST/TREE MGT. PLANS • EXPERT TESTIMONY
Member of International Society of Arboriculture and Society of American Foresters
-Preliminary Tree Conservation Plan -
FEDERAL WAY OPERATIONS & MAINENANCE FACILITY
28th Avenue South
Federal Way, WA
Prepared for: AHBL, Inc.
Prepared by: Washington Forestry Consultants, Inc.
Date of Report: October 20, 2023
Introduction
The project proponent is planning to develop 14 parcels totaling 13.87-acres in Federal Way,
Washington. The proponent has retained WFCI to:
•Complete and inventory and assessment of the trees on the site.
•Make recommendations for retention, removal, protection, and/or cultural care.
•Complete tree retention and replacement calculations according to Federal Way
Municipal Code 19.120.130.
•Prepare a tree protection plan.
Observations
Methodology
WFCI has evaluated significant trees 6 inches diameter at breast height (DBH) and larger in the
proposed project area and assessed their potential to be incorporated into the new project. The
entire site was 100% inventoried using a dot tally to count the number of trees within the project
area. Trees were assessed as healthy or unhealthy trees.
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Site Description
The project area includes 14 parcels totaling 13.87-acres. Parcel numbers of the project are
0921049315, 0921049314, 0921049313, 0921049075, 0921049084, 0921049239, 0921049095,
0921049115, 0921049085, 0921049170, 0921049009, 0921049250, 0921049198, and
0921049026. There are homes, outbuildings, maintenance facilities, paved areas, and other
improvements located on the project site. The topography is generally flat north to south and
moderately sloping to the east down to I-5. The project area is bordered by I-5 to the east, an
apartment complex to the south, 28th Avenue South to the west, and single-family homes to the
north.
Soil Depth and Productivity
According to the Natural Resource Soil Conservation Survey the soil types on the site are two
variants of the Alderwood gravelly sandy loam.
Figure 1. Soil Map of Federal Way Operations and Maintenance Facility Site.
AgB – Alderwood gravelly sandy loam 0 – 8%
AgC – Alderwood gravelly sandy loam 8 – 15%
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The two soil types are the Alderwood gravelly sandy loam, a moderately deep, moderately well
drained soil found on glacial till plains. It is formed in ablation till overlying basal till. A weakly
cemented hardpan is at a depth of 20 to 40 inches. Permeability is moderately rapid above the
hardpan and very slow in the pan. Available water capacity is low. Effective rooting depth is 20-
40 inches. A perched seasonal high-water table is at a depth of 18-36 inches from November to
March. The potential for windthrow of trees is moderate under normal conditions. New trees
require irrigation for establishment.
In areas where grading brings the hardpan nearer to the surface, the hardpan must be
fractured under new trees to provide soil volume for root development and to improve
drainage around the tree.
Tree Conditions
There are three forest cover types on the site for the purposes of description. The cover type
boundary delineation is shown on the aerial photo in Attachment 1.
Type I. – This cover type is the largest stand of trees on the project site. It is a native stand of
bigleaf maple (Acer macrophyllum), black cottonwood (Populus trichocarpa), Douglas-fir
(Pseudotsuga menziesii), western redcedar (Thuja plicata), red alder (Alnus rubra), western
hemlock (Tsuga heterophylla), Pacific madrone (Arbutus menziesii), and Scouler’s willow (Salix
scouleriana). The inventory found 268 trees growing in this type. The diameter range for the
trees is from 6 to 50 inches DBH. Seventy-two percent of the trees are in ‘Fair’ or better condition.
The type is dominated by red alder and bigleaf maples that are overmature with significant decay
and previous top failures. The best trees to retain in this type are the western redcedar and Douglas-
fir.
Table 1. Summary of Trees in Cover Type I.
Species DBH
Range (in.)
Condition
Range
# of Healthy
Significant
Trees
# of
Unhealthy
Significant
Trees
Total # of
Trees
Bigleaf Maple 6 – 50 Very Poor – Fair 82 18 100
Black Cottonwood 28 – 30 Fair 2 0 2
Douglas-fir 6 – 34 Fair – Good 20 0 20
Pacific Madrone 14 – 20 Fair 2 0 2
Red Alder 8 – 26 Dead – Fair 29 52 81
Scouler’s Willow 6 – 15 Very Poor – Fair 1 5 6
Western Hemlock 12 – 25 Dead – Fair 2 4 6
Western Redcedar 6 – 45 Dead – Good 37 14 51
Total 6 – 50 Dead - Good 175 93 268
The understory vegetation is dense with salmon berry (Rubus spectabilis), sword fern (Polystichum
munitum), red huckleberry (Vaccinium parvifolium), bracken fern (Pteridium aquilinum),
Himalayan black berry (Rubus armeniacus), and trailing blackberry (Rubus ursinus). There was
also invasive Japanese knotweed (Reynoutria japonica) growing in the understory.
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Photo 1. View of typical trees and understory vegetation in Cover Type I.
Type II. – This cover type encompasses all the trees around the existing homes. The trees in this
type include both native and planted species. Species include Douglas-fir, cherry (Prunus spp.),
western redcedar, shore pine (Pinus contorta), coastal redwood (Sequoia sempervirens), bigleaf
maple, hawthorn (Crataegus spp.), Pacific dogwood (Cornus nuttallii), giant sequoia
(Sequoiadendron giganteum), Colorado blue spruce (Picea pungens), Alaska cedar (Callitropsis
nootkatensis), silver maple (Acer saccharinum), horse chestnut (Aesculus hippocastanum),
European white birch (Betula pendulum), black locust (Robinia pseudoacacia), Leyland cypress
(Cupressus × leylandii), Lombardy poplar (Populus nigra), English walnut (Juglans regia),
Japanese maple (Acer palmatum), apple (Malus spp.), Chinese windmill palm (Trachycarpus
fortune), arborvitae (Thuja spp.), and other hardwoods. Almost all of the trees in this type are in
‘Fair’ or better condition. The diameter range for the trees is from 6 to 48 inches DBH. The
conifer in this type would make the best retention trees to save on-site.
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Table 2. Summary of Trees in Cover Type II.
Species
DBH
Range
(in.)
Condition
Range
# of Healthy
Significant
Trees
# of
Unhealthy
Significant
Trees
Total # of
Trees
Douglas-fir 6 – 40 Fair – Good 21 0 21
Cherry 8 – 15 Fair 7 0 7
Western Redcedar 6 – 44 Fair – Good 19 0 19
Shore Pine 15 – 22 Fair 4 0 4
Coastal Redwood 20 – 26 Good 2 0 2
Bigleaf Maple 6 - 48 Fair 27 0 27
Hawthorn 12 – 14 Fair 2 0 2
Pacific Dogwood 6 – 22 Dead – Fair 1 1 2
Giant Sequioa 20 Good 1 0 1
Colorado Blue
Spruce 15 Good 1 0 1
Alaska Cedar 14 – 24 Good 3 0 3
Silver Maple 10 – 26 Fair 4 0 4
Horse Chestnut 16 Fair 2 0 2
European White
Birch 15 Fair 1 0 1
Black Locust 6 – 24 Fair 14 0 14
Leyland Cypress 10 – 12 Good 8 0 8
Lombardy Poplar 24 – 30 Fair 4 0 4
English Walnut 10 – 15 Good 3 0 3
Japanese Maple 6 – 18 Good 2 0 2
Apple 6 – 16 Fair 13 0 13
Arborvitae 6 Good 14 0 14
Chinese Windmill
Palm 10 Good 1 0 1
Other Hardwoods 6 - 10 Fair 5 0 5
Total 15 – 28 ‘Dead’ – ‘Fair’ 159 1 160
The understory vegetation is sparse with planted shrubs in the landscape, grass, and annual weeds.
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Photo 2. View of typical trees Cover Type II.
Type III. – This forest cover type is the cleared, non-forest existing maintenance facility in the
southern area of the site. There are a small number of trees within the landscape areas. All of the
trees in this type are suitable for retention.
Table 3. Summary of Trees in Cover Type III.
Species DBH
Range (in.)
Condition
Range
# of Healthy
Significant
Trees
# of
Unhealthy
Significant
Trees
Total # of
Trees
Douglas-fir 12 – 36 Fair – Good 11 0 11
Western Redcedar 6 – 38 Fair – Good 7 0 7
Giant Sequoia 6 – 54 Good 2 0 2
Mountain Ash 18 Fair 2 0 1
Norway Maple 12 Good 1 0 1
Vine Maple 6 Good 1 0 1
Other Hardwood 8 – 14 Fair 2 0 2
Total 6 – 54 Fair – Good 26 0 26
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The understory vegetation is very sparse and consists of shrubs in the landscape, grasses, and
annual weeds.
Photo 3. View of typical plants in Cover Type III.
Overall Summary of Trees
There are a total of 454 trees of which 360 are in ‘Fair’ or better condition. Trees in ‘Poor’, ‘Very
Poor’, or that are ‘Dead’ are not considered to be long-term trees. These unhealthy trees have no
potential to be saved in a development project.
Off-Site Impacts
Tree removal and grading for this project may impact off-site trees on the eastern side of the project
area along the I-5 and Sound Transit rights-of-way. A tree risk assessment should be conducted
on these trees after site clearing.
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Planned Tree Retention
The current site plan shows the potential to retain 80 trees in the perimeter areas of the project.
The required grading and other improvements limit tree retention on the remainder of the site.
Once civil and grading plans are finalized a concluding count can be made to determine the total
number of trees saved.
Table 4. Planned Tree Retention:
Existing Tree Diameters
Tree
Unit
Credits
# of Trees
in
Perimeter
Area
Total
Tree
Units
Saved
Existing Trees >6" to 12" DBH 1.5 23 34.5
Existing Trees >12" to 18" DBH 2.0 21 42
Existing Trees >18" to 24" DBH 2.5 14 35
Existing Trees >24 DBH 3.0 22 66
Totals 80 177.5
Tree Retention Calculations
Federal Way municipal code 19.120.130 requires a minimum tree unit density of 25 tree units per
acre for the current Single-family Residential zoning of the 14 parcels. If the zoning changes the
density requirement will also change.
The following is a summary of the planned tree retention and removal:
Total Project Acreage: 13.87 acres
Minimum Density Requirement
(25 tree units/acre x 13.87 acres): 347.0 tree units
Planned Tree Retention: 177.5 tree units
Shortfall of Tree Unit Requirement: 169.5 tree units
By retaining 177.5 tree units in 80 significant trees on the site, this plan falls short of the minimum
tree density requirement by169.5 tree units. To meet the minimum tree density requirement
replacement trees shall be planted. Replacement tree categories include small, medium, and large
canopy species. Small canopy species count as 0.50 tree units, medium canopy species are 1.0
tree units, and large canopy species are 1.5 tree units. Different sized trees can be planted in
combination to replace the tree unit deficit.
Tree Protection Measures
Trees to be saved must be protected during construction by a six-foot-high chain link fencing
(Attachment 2), located 5 feet outside of the drip line of the trees. An existing fence surrounds
much of the property – this should be adequate to protect these edges. Placards shall be placed
on the fencing every 50 feet indicating the words, "NO TRESPASSING - Protected Trees". The
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individual RPZ are a radius of one foot for each one inch of DBH (6 feet minimum), unless
otherwise delineated by WFCI.
There should be no equipment activity (including rototilling) within the critical root zone. No
irrigation lines, trenches, or other utilities should be installed within the CRZ. Cuts or fills should
impact no more than 25% of a tree’s root system. If topsoil is added to the root zone of a protected
tree, the depth should not exceed 2 inches of a sandy loam or loamy fine sand topsoil and should
not cover more than 25% of the root system.
If roots are encountered outside the RPZ during construction, they should be cut cleanly with a
saw and covered immediately with moist soil. Noxious vegetation within the critical root zone
should be removed by hand. If a proposed save-tree must be impacting by grading or fills, then
the tree should be re-evaluated by WFCI to determine if the tree can be saved with mitigating
measures, or if the tree should be removed.
Pruning and Thinning
All individual trees to be saved near or within developed areas should have their crowns raised to
provide a minimum of 8 feet of ground clearance over sidewalks and landscape areas, 15 feet over
parking lots or streets, and at least 10 feet of building clearance.
All pruning should be done according to the ANSI A300 standards for proper pruning, and be
completed by an International Society of Arboriculture Certified Arborist®, or be supervised by a
Certified Arborist®.
Conclusions and Timeline for Activity
1. The final, approved tree conservation plan map should be included in the construction
drawings for bid and construction of the project and should be labeled as such.
2. Stake and heavily flag the clearing limits.
3. Contact WFCI to attend pre-job conference and discuss tree protection issues with contractors.
WFCI can verify all trees to be saved and/or removed are adequately marked for retention.
WFCI can inspect and mark any additional hazard trees or trees that will be impacted by
grading, trenching or development for removal in the save tree areas.
4. Complete logging. Complete necessary hazard tree removals and invasive plant removals from
the tree protection areas. No equipment should enter the tree protection areas during logging.
WFCI should inspect the save trees after logging, to identify any trees that may have been
damaged, or any other hazard trees. The logger can then remove these trees before they depart
the site.
5. Install tree protection fences along the 'limits of construction'. The fences should be located at
the limits of construction or 5 feet outside of the drip line of the save tree or as otherwise
specified by WFCI.
6. Complete clearing of the project. Maintain fences throughout construction.
7. Do not excavate stumps within 10’ of trees to be saved. These should be individually evaluated
by WFCI to determine the method of removal.
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8. Complete all necessary pruning on save trees or stand edges to provide at least 8’ of ground
clearance near sidewalks and trails, and 15’ above all driveways or access roads.
9. Complete grading and construction of the project.
Summary
Federal Way municipal code 19.120.130 requires a minimum tree unit density of 25 tree units per
acre for net developable acreage on Single-family Residential sites. The developable area is 13.87
acres, requiring 347.0 tree units to be retained on site. Eighty (80) healthy trees are planned to be
retained on the site for a total of 177.5 tree units. This falls short of the required tree unit retention
by 169.5 tree units. Small, medium, or large canopy trees shall be used to replace the tree unit
shortfall.
Please give us a call if you have any further questions.
Respectfully submitted,
Washington Forestry Consultants, Inc.
Galen M. Wright, ACF, ASCA Joshua Sharpes
ISA Bd. Certified Master Arborist PN-129BU Professional Forester
Certified Forester No. 44 ISA Certified Arborist®,
ISA Tree Risk Assessor Qualified Municipal Specialist, PN- 5939AM
ASCA Tree and Plant Appraisal Qualified ISA Tree Risk Assessor Qualified
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Attachment 1. Aerial Photo of Federal Way Operations and Maintenance
Facility Site
(King County iMap 2021)
Project Boundary
Forest Cover Type Boundaries
I
I
NORTH
NO SCALE
III
II
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Attachment 2. Federal Way Operations and Maintenance Facility Site Plan
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Project Boundary
Planned Save Tree
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Attachment 3. Tree Protection Fence Detail
Temporary Chain Link on Driven Posts
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Attachment 4. Individual Tree Rating Key for Tree Condition
RATING SYMBOL DEFINITION
Very Good VG • Balanced crown that is characteristic of the species
• Normal lateral and terminal branch growth rates for the species and
soil type
• Stem sound, normal bark vigor
• No root problems
• No insect or disease problems
• Long-term, attractive tree
Good G • Crown lacking symmetry but nearly balanced
• Normal lateral and terminal branch growth rates for the species and
soil type
• Minor twig dieback O.K.
• Stem sound, normal bark vigor
• No root problems
• No or minor insect or disease problems – insignificant
• Long-term tree
Fair F • Crown lacking symmetry due to branch loss
• Slow lateral and terminal branch growth rates for the species and
soil type
• Minor and major twig dieback – starting to decline
• Stem partly unsound, slow diameter growth and low bark vigor
• Minor root problems
• Minor insect or disease problems
• Short-term tree 10-30 years
Poor P • Major branch loss – unsymmetrical crown
• Greatly reduced growth
• Several structurally import dead or branch scaffold branches
• Stem has bark loss and significant decay with poor bark vigor
• Root damage
• Insect or disease problems – remedy required
• Short-term tree 1-10 years
Very Poor VP • Lacking adequate live crown for survival and growth
• Severe decline
• Minor and major twig dieback
• Stem unsound, bark sloughing, previous stem or large branch
failures, very poor bark vigor
• Severe root problems or disease
• No or minor insect or disease problems
• Mortality expected within the next few years
Dead DEAD • Dead
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Attachment 5. Assumptions and Limiting Conditions
1) Any legal description provided to the Washington Forestry Consultants, Inc. is assumed to be correct.
Any titles and ownership's to any property are assumed to be good and marketable. No responsibility
is assumed for matters legal in character. Any and all property is appraised or evaluated as though
free and clear, under responsible ownership and competent management.
2) It is assumed that any property is not in violation of any applicable codes, ordinances, statutes, or
other governmental regulations, unless otherwise stated.
3) Care has been taken to obtain all information from reliable sources. All data has been verified insofar
as possible; however, Washington Forestry Consultants, Inc. can neither guarantee nor be responsible
for the accuracy of information.
4) Washington Forestry Consultants, Inc. shall not be required to give testimony or to attend court by
reason of this report unless subsequent contractual arrangements are made, including payment of an
additional fee for such services as described in the fee schedule and contract of engagement.
5) Loss or alteration of any part of this report invalidated the entire report.
6) Possession of this report or a copy thereof does not imply right of publication or use for any purpose
by any other than the person to whom it is addressed, without the prior expressed written or verbal
consent of Washington Forestry Consultants, Inc.
7) Neither all or any part of the contents of this report, nor copy thereof, shall be conveyed by anyone,
including the client, to the public through advertising, public relations, news, sales or other media,
without the prior expressed written or verbal consent of Washington Forestry Consultants, Inc. --
particularly as to value conclusions, identity of Washington Forestry Consultants, Inc., or any
reference to any professional society or to any initialed designation conferred upon Washington
Forestry Consultants, Inc. as stated in its qualifications.
8) This report and any values expressed herein represent the opinion of Washington Forestry
Consultants, Inc., and the fee is in no way contingent upon the reporting of a specified value, a
stipulated result, the occurrence neither of a subsequent event, nor upon any finding in to reported.
9) Sketches, diagrams, graphs, and photographs in this report, being intended as visual aids, are not
necessarily to scale and should not be construed as engineering or architectural reports or surveys.
10) Unless expressed otherwise: 1) information contained in this report covers only those items that were
examined and reflects the condition of those items at the time of inspection; and 2) the inspection is
limited to visual examination of accessible items without dissection, excavation, probing, or coring.
There is no warranty or guarantee, expressed or implied, that problems or deficiencies of the tree or
other plant or property in question may not arise in the future.
Note: Even healthy trees can fail under normal or storm conditions. The only way to eliminate all risk is
to remove all trees within reach of all targets. Annual monitoring by an ISA Certified Arborist or Certified
Forester will reduce the potential of tree failures. It is impossible to predict with certainty that a tree will
stand or fail, or the timing of the failure. It is considered an ‘Act of God’ when a tree fails, unless it is
directly felled or pushed over by man’s actions.