17-105489-Tree and Vegetation Retention Plan-11-12-2021-V2 WASHINGTON 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
- Updated Tree and Vegetation Retention Plan -
WOODBRIDGE CORPORATE PARK
32901 Weyerhaeuser Way S.
Federal Way WA 98001
Prepared for: Federal Way Campus LLC
Prepared by: Washington Forestry Consultants, Inc.
Date of Report: November 9, 2021
Introduction
The project proponent is planning to construct 3 commercial buildings on 97.7 acres in Federal
Way WA. The proponent has retained WFCI to:
• Evaluate and inventory all trees on the site pursuant to the requirements of Section 22-1568
of 1994 Federal Way City Code (1994 FWCC), in compliance with the Weyerhaeuser
Company Concomitant Pre-Annexation Developer Agreement, dated August 23, 1994.
• Make recommendations for retention of significant trees, along with required protection and
cultural measures.
• Complete the minimum stocking requirement calculations for the project.
Observations
Methodology
The forest inventory was conducted using variable area plots on a systematic grid across the
forested area of the project. To improve sample predictions of species, size, stand stocking and
quality the forest stands were stratified into 9 forested cover types.
All species and all trees 6 inches DBH and larger were inventoried, however only trees 12 inches
in diameter at breast height (DBH) or greater are reported as significant trees. In addition, red
alder, black cottonwood, other Populus species, and bigleaf maple are not considered to be
significant trees by the 1994 ordinance. The forest inventory data was processed using
SuperAce®, a forest inventory processing software program.
Woodbridge Corporate Park – Updated Tree and Vegetation Retention Plan
Washington Forestry Consultants, Inc. Page 2
The tree evaluation phase used methodology developed by Matheny and Clark (1998) in their
text Trees and Development: A Technical Guide to Preservation of Trees during Land
Development, published by the International Society of Arboriculture, Champaign, IL 1998.
In all cases, the overall health of the tree was considered relative to its ability to add value to the
new project. The potential for incorporation into the project design has been evaluated as well.
Trees that are retained near new construction must be carefully selected to make sure that they
can survive construction impacts, adapt to a new environment and perform well in the landscape.
Healthy, vigorous trees are better able to tolerate impacts such as root injury, changes in soils
moisture regimes, and soil compaction than are low vigor trees.
Structural characteristics are also important in assessing suitability. Trees with significant decay
and other structural defects that cannot be treated are likely to fail. Such trees should not be
retained in areas where damage to people or property could occur.
Site Description
The project area consists of portions of 3 parcels totaling 97.7 acres. The topography is mostly
flat to gently rolling. The site is bordered to the north by commercial properties, to the west by
Interstate 5, to the south by undeveloped forest and pasture, and to the east by Weyerhaeuser
Way South.
Many small wetlands occur sporadically on the west side of the project area near Interstate 5.
There is a large commercial office building and associated parking lot in the central portion of
the project area. An additional small office building exists on the eastern side of the property.
Access to the site is by Weyerhaeuser Way S. Numerous trails and small roads traverse the
ownership.
Soil Depth and Productivity
According to the USDA Natural Resource Conservation Service Web Soil Survey, there is 1 soil
type in the project area - the Alderwood gravelly sandy loam.
The predominant soil type on the property is the Alderwood gravelly sandy loam. The
Alderwood gravelly sandy is 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 Alderwood 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.
Woodbridge Corporate Park – Updated Tree and Vegetation Retention Plan
Washington Forestry Consultants, Inc. Page 3
Figure 1. Soils Map of Woodbridge Corporate Park Project Area
Project Area Boundary
Ag - Alderwood gravelly sandy loam - 100%
Existing Tree Conditions
There are 9 forest cover types for the purposes of description. The location and extent of each
cover type is illustrated on the aerial photograph in Attachment 1.
Forest Cover Type I. – This approximately 33.9 acre type includes the developed portion of the
project area (17.4 acres) and the treed areas between the parking lot, along with the open stand
on the south end of the project.
Major tree species include western redcedar (Thuja plicata), Douglas-fir (Pseudotsuga
menziesii), and bigleaf maple (Acer macrophyllum). Many planted ornamental tree species also
occur in this cover type, including Norway maple (Acer platanoides), sycamore maple (Acer
pseudoplatanus), Atlas cedar (Cedrus atlantica), deodar cedar (Cedrus deodara), katsura
(Cercidiphyllum japonicum), Turkish filbert (Corylus maxima), European beech (Fagus
sylvatica), western larch (Larix occidentalis), sweet-gum (Liquidambar styraciflua), wild cherry
N
Ag
Woodbridge Corporate Park – Updated Tree and Vegetation Retention Plan
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(Prunus avium), flowering cherry (Prunus serrulata), white oak (Quercus alba), cascara
(Rhamnus purshiana), giant sequoia (Sequoiadendron giganteum), lodgepole pine (Pinus
contorta), western white pine (Pinus monticola), Leyland cypress (Cupressocyparis x. leylandii),
and European linden (Tilia platyphyllos).
Tree size ranges from 12 to 57 inches DBH. There are 29 significant trees per Acre (TPA), or
988 total significant trees in the 33.9-acre cover type. Tree condition ranges from ‘Poor’ to
‘Good,’ with the vast majority (98%) of trees described as healthy (‘Fair’ condition or better).
Photo 1. View of trees in Cover Type I
Understory vegetation consists of mostly native plants and some non-native, invasive species.
Native species include vine maple (Acer circinatum), western hazel (Corylus cornuta), Indian-
plum (Oemleria cerasiformis), salal (Gaultheria shallon), thimbleberry (Rubus parviflorus),
trailing blackberry (Rubus ursinus), snowberry (Symphoricarpos alba), prostrate Oregon-grape
(Mahonia nervosa), sword fern (Polystichum munitum), and bracken fern (Pteridium aquilinum).
Invasive plants include English ivy (Hedera helix), blackberry (Rubus armeniacus), grasses, and
broadleaved weeds. This community of understory vegetation is common throughout the project
area.
Table 1. Summary of Significant and Other Trees in Cover Type I
Species DBH Range (in.) Condition Range
Total # Trees
Per Acre
Total # Healthy
Significant Trees
Douglas-fir 12 - 38 ‘Fair’ - ‘Good’ 18 167
Western Redcedar 12 - 57 ‘Poor’ - ‘Good’ 27 242
Bigleaf Maple* 32 - 53 ‘Poor’ - ‘Fair’ <1 0
Other Conifer 15 - 28 ‘Fair’ - ‘Good’ 8 80
Other Hardwood 12 - 20 ‘Fair’ - ‘Good’ 33 499
Total 12 - 57 ‘Poor’ - ‘Good’ 87 988
*Not Considered Significant under 1994 Definition
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Forest Cover Type II. -- Type II is a mature stand of Douglas-fir with some bigleaf maple, red
alder (Alnus rubra), and planted ornamental trees. Tree size ranges from 12 to 46 in. DBH.
There are 80 total trees per acre and 451 significant trees (54.7 Sign. Trees/ac) across the 8.25-
acre cover type. Tree condition ranges from ‘Dead’ to ‘Good,’ with most trees described as
being in ‘Fair’ condition or better.
Photo 2. View of trees in Cover Type II
Understory vegetation is similar to Cover Type I, but denser and more contiguous. Elderberry
(Sambucus racemosa) and red mountain huckleberry (Vaccinium parvifolium) are also present.
Table 2. Summary of Trees in Cover Type II
Species DBH Range (in.) Condition Range
Total # Trees
Per Acre
Total # Healthy
Significant Trees
Douglas-fir 15 - 46 ‘Fair’ - ‘Good’ 55 451
Red Alder* 12 - 15 ‘Poor’ 13 0
Bigleaf Maple* 12 - 17 ‘Fair’ 4 0
Other Conifer 12 - 24 ‘Poor’ 8 0
Total 12 - 46 ‘Poor’ - ‘Good’ 80 451
*Not Considered Significant under 1994 Definition
Cover Type III. -- Type III is a low-density, mixed stand of mostly deciduous trees including
mostly red alder and black cottonwood. Some large Douglas-fir and western redcedar trees also
occur in this cover type, but are widely scattered. Tree size ranges from 15 to 48 inches DBH.
There are 60 total trees per acre and 35 significant trees (4.7 Sign. Trees/ac) over the 7.5-acre
cover type. Tree condition ranges from ‘Dead’ to ‘Good,’ with most trees described as being in
‘Fair’ condition or better.
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Table 3. Summary of Trees in Cover Type III
Species DBH Range (in.) Condition Range
Total Trees Per
Acre
Total # Healthy
Significant Trees
Douglas-fir 28 - 46 ‘Fair’ - ‘Good’ 5 35
Red Alder* 15 - 23 ‘Poor’ 23 0
Black Cottonwood* 20 - 48 ‘Fair’ <1 0
Western Redcedar 24 - 40 ‘Poor’ 1 0
Total 15 - 48 ‘Poor’ - ‘Good’ 30 35
*Not Considered Significant under 1994 Definition
Photo 3. View of trees in Cover Type III
Understory vegetation is very dense and consists of mostly native plants and some non-native,
invasive species. Native species include vine maple, western hazel, Indian-plum, salal, trailing
blackberry, snowberry, prostrate Oregon-grape, sword fern, and bracken fern. Invasive plants
include English ivy, blackberry, grasses, and broadleaved weeds.
Forest Cover Type IV. -- Type IV is a dense plantation of predominantly Douglas-fir trees with a
lesser numbers of deciduous trees and exotic conifers such as Norway spruce (Picea abies). Tree
size ranges from 12 to 69 in. DBH, but are most commonly in the 14 to 16 inch DBH range.
There are 162 total trees per acre and 1,956 healthy, significant trees over the 13.5-acre cover
type. Tree condition ranges from ‘Dead’ to ‘Good,’ with most trees (90%) described as being in
‘Fair’ condition or better.
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Table 4. Summary of Trees in Cover Type IV
Species DBH Range (in.) Condition Range
Total # Trees
Per Acre
Total # Healthy
Significant Trees
Douglas-fir 12 - 36 ‘Fair’ - ‘Good’ 149 1,785
Other Conifer 12 - 13 ‘Poor’ 7 98
Black Cottonwood* 69 ‘Fair’ <1 0
Other Hardwood 24 - 40 ‘Poor’ 5 73
Total 12 - 69 ‘Poor’ - ‘Good’ 162 1,956
*Not Considered Significant under 1994 Definition
Photo 4. View of trees in Cover Type IV
Understory vegetation is less dense than other cover types and consists of mostly native plants.
Species include vine maple, woods rose (Rosa woodsia), Indian-plum, salal, trailing blackberry,
snowberry, prostrate Oregon-grape, sword fern, and bracken fern.
Forest Cover Type V. -- Type V is a mixed stand of mostly native and planted deciduous trees
and conifers including Douglas-fir, black cottonwood, European linden, European birch (Betula
pendula), and western larch (Larix occidentalis). Tree size ranges from 13 to 29 inches DBH.
There are 129 total trees per acre in this cover type and 425 significant trees over the 4.25-acre
cover type. Tree condition ranges from ‘Poor’ to ‘Good,’ with most trees described as being in
‘Fair’ condition or better.
Table 5. Summary of Trees in Cover Type V
Species DBH Range (in.) Condition Range
Total # Trees
Per Acre
Total # Healthy
Significant Trees
Douglas-fir 18 - 19 ‘Fair’ - ‘Good’ 21 91
Other Conifer 12 - 13 ‘Poor’ 51 108
Black Cottonwood* 29 ‘Fair’ 4 0
Other Hardwood 24 - 40 ‘Poor’ 53 226
Total 12 - 40 ‘Poor’ - ‘Good’ 129 425
*Not Considered Significant under 1994 Definition
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Photo 5. View of trees in Cover Type V
Understory vegetation consists of mostly native plants and some non-native, invasive species.
Native species include Indian-plum, salal, trailing blackberry, prostrate Oregon-grape, sword
fern, and bracken fern. Invasive plants include English ivy, and blackberry.
Forest Cover Type VI. -- Type VI is a high-density plantation of small deciduous trees with a
few conifers mixed in. An exotic species of ash (Fraxinus spp.) is dominant. Scattered Douglas-
fir, giant Sequoia, Nordmann fir (Abies nordmaniana) and western larch trees also occur. Tree
size ranges from 12 to 42 inches DBH. There are 84 trees per acre and 535 significant trees over
the 6.5-acre cover type. Tree condition ranges from ‘Dead’ to ‘Good,’ with most trees described
as being in ‘Fair’ condition or better.
Table 6. Summary of Trees in Cover Type VI
Species DBH Range (in.) Condition Range
Total # Trees
Per Acre
Total # Healthy
Significant Trees
Other Conifer 12 - 13 Good 7 45
Ash 24 - 42 ‘Poor’ 77 490
Total 12 - 42 ‘Poor’ - ‘Good’ 84 535
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Washington Forestry Consultants, Inc. Page 9
Photo 6. View of trees in Cover Type VI
Understory vegetation is very dense and consists mostly of invasive blackberry. Occasional
native species include Indian-plum, salal, trailing blackberry, prostrate Oregon-grape, elderberry,
sword fern, and bracken fern.
Forest Cover Type VII. -- Type VII is a poorly stocked stand of low-quality deciduous trees with
a few conifers intermixed. Species include mostly black cottonwood, bigleaf maple, and white
poplar (Populus alba), with a few small, scattered western redcedars, and Douglas-firs, most of
which are not significant. Tree size is relatively large and ranges from 12 to 56 inches DBH.
There are 29 trees per acre and 106 significant trees over the 10.8-acre cover type. Tree
condition ranges from ‘Dead’ to ‘Good,’ with most trees described as being in ‘Poor’ condition
or worse.
Table 7. Summary of Trees in Cover Type VII
Species DBH Range (in.) Condition Range
Total # Trees
Per Acre
Total # Healthy
Significant Trees
Douglas-fir 14 - 18 ‘Dead’ - ‘Fair’ 9 77
Bigleaf Maple* 12 - 13 ‘Poor’ 1 0
Poplar* 18 - 56 ‘Fair’ 16 0
Western Redcedar 12 - 26 ‘Poor’ - ‘Good’ 3 29
Total 12 - 56 ‘Dead’ - ‘Good’ 29 106
*Not Considered Significant under 1994 Definition
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Washington Forestry Consultants, Inc. Page 10
Photo 7. View of trees in Cover Type VII – type is to the right.
Understory vegetation consists of equal parts native plants and non-native, invasive species.
Native species include salmonberry (Rubus spectabilis), western hazel, Indian-plum, salal,
trailing blackberry, snowberry, prostrate Oregon-grape, sword fern, and bracken fern. Invasive
plants include English ivy, blackberry, grasses, and broadleaved weeds.
Forest Cover Type VIII. -- Type VIII is a managed stand of mature western redcedar trees. A
few red alder, Douglas-fir, and western hemlock (Tsuga heterophylla) can also be found in this
type. Ornamental trees are also present along Weyerhaeuser Way S., including Norway spruce,
and golden-rain tree (Laburnum vossii). Tree size is relatively large and ranges from 12 to 62
inches DBH. There are 49 trees per acre and 360 healthy, significant trees over the 9.5-acre
cover type. Tree condition ranges from ‘Very Poor’ to ‘Good,’ with most trees described as
being in ‘Fair’ condition or better.
Table 8. Summary of Trees in Cover Type VIII
Species DBH Range (in.) Condition Range
Total # Trees
Per Acre
Total # Healthy
Significant Trees
Douglas-fir 31 - 38 ‘Good’ 5 48
Red Alder* 12 - 13 ‘Poor’ 6 0
Western Hemlock 18 - 56 ‘Poor’ - ‘Good’ 11 92
Western Redcedar 12 - 26 ‘Poor’ 27 220
Total 12 - 56 ‘Dead’ - ‘Good’ 49 360
*Not Considered Significant under 1994 Definition
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Washington Forestry Consultants, Inc. Page 11
Photo 8. View of trees in Cover Type VIII
Understory vegetation is very dense and consists of mostly native plants. Species include
western hazel, Indian-plum, salal, trailing blackberry, prostrate Oregon-grape, sword fern, and
bracken fern. Other plants include blackberry and foxglove (Digitalis purpurea).
Forest Cover Type IX. -- Type IX is a mixed stand of mature black cottonwood, red alder, and
western redcedar. Some Douglas-fir, Oregon ash (Fraxinus latifolia) and bigleaf maple trees
occur in the intermediate crown class. Tree size is relatively large and ranges from 12 to 56
inches DBH. There are 19 trees per acre and 16 healthy, significant trees over the 3.5-acre cover
type. Tree condition ranges from ‘Very Poor’ to ‘Good,’ with most trees described as being in
‘Fair’ condition or better.
Table 9. Summary of Trees in Cover Type IX
Species DBH Range (in.) Condition Range
Total # Trees
Per Acre
Total # Healthy
Significant Trees
Douglas-fir 31 - 38 ‘Good’ 2 7
Red Alder* 12 - 13 ‘Poor’ 13 0
Black Cottonwood* 18 - 56 ‘Poor’ - ‘Good’ 1 0
Western Redcedar 12 - 26 ‘Fair’ 3 9
Total 12 - 56 ‘Poor’ - ‘Good’ 19 16
*Not Considered Significant under 1994 Definition
Woodbridge Corporate Park – Updated Tree and Vegetation Retention Plan
Washington Forestry Consultants, Inc. Page 12
Photo 9. View of trees in Cover Type IX
Understory vegetation is very dense and consists of mostly native plants and some non-native,
invasive species. Native species include salmonberry, vine maple, cascara, western hazel,
Indian-plum, salal, trailing blackberry, prostrate Oregon-grape, sword fern, and bracken fern.
Invasive plants include English ivy, blackberry, grasses, and broadleaved weeds.
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Summary of All Cover Types
A total of about 80 acres of the 97.7-acre project area are forested by 9 distinct forest cover
types. The following table summarizes all cover types and significant trees in the Woodbridge
Corporate Park project area.
Table 10. Summary of all Cover Types in the project.
Type Acres
#
Significant
Trees
#
Significant
Trees/Acre
I 33.9 988 29.1
II 8.25 451 54.7
III 7.5 35 4.7
IV 13.5 1,956 144.9
V 4.25 425 100.0
VI 6.5 535 82.3
VII 10.8 106 9.8
VIII 9.5 360 37.9
IX 3.5 16 4.6
Sum 97.7 4,872 50.0
Overall, the buildable area of the project has the following species composition:
Table 11. Species composition of the forest stands across the 97.7 acre project area.
Species DBH Range (in.)
Total # Healthy
Significant Trees
% Composition of
Significant Trees
Douglas-fir 12 - 52 2,802 58
Western Redcedar 12 - 57 792 16
Western Hemlock 18 - 56 92 2
Oregon Ash*** 8 - 10 0 0
Other Conifer 12 - 24 81 2
Other Hardwood** 12 - 40 1,105 22
Red Alder* 12 - 28 0 0
Black Cottonwood* 12 - 69 0 0
Total 8 - 69 4,872 100
*Not Considered Significant under 1994 Definition
**Includes non-native Ash Trees
***All in ‘Poor’ condition
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Discussion
The 1994 Federal Way City Code requires 25% of the significant trees to be retained on
commercial projects. The following is a summary of the tree retention calculations.
Total Project Acreage 97.70 acres
Critical Areas and their Buffers 13.16 acres
Buildable Area 84.54 acres’
Total # of Significant Trees in Buildable Area of Project 4,227
(50 trees/acre x 84.54 acres)
Required Tree Retention (25% x 4,227) 1,057
Managed Forest Buffer – Significant Trees Retained 206
Other Retained Sign. Interior Trees – (10.98 acres x 50 Trees/ac. x 2) 1,098
Total Healthy Significant Trees Retained on Site 1,304
Surplus of Tree Retention above Minimum Requirement 247
The 1994 Federal Way City Code states that significant trees not located in the perimeter
landscaping may be credited as two trees for the purpose of retention requirements. This means
that the 549 interior trees on 10.98 acres count as 1,098 trees when calculating tree retention.
By retaining 1,304 healthy (31%) significant trees in the project area, this plan exceeds the 25%
minimum retention requirement described in Federal Way City Code (1994) by 6%. We project
that an additional 382 healthy trees of a significant tree species that are smaller than 12”, are also
being retained. Further, there will be healthy red alders interspersed within the tree retention
areas that will be retained, though they are not considered significant.
Tree Protection Measures
Trees that are saved must be protected during construction by temporary chain-link fencing on
driven posts (Attachment 4), located at the edge of the critical root zone for the protected tract, or
individual trees if they occur. The individual critical root zones are 5 feet outside the dripline of
all edge trees unless otherwise delineated by WFCI.
There should be no equipment activity within the critical root zone. No irrigation lines, trenches,
or other utilities should be installed within the critical root zone. If roots are encountered outside
the critical root zone, 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 impacted by grading or fills, then the tree should be re-evaluated by WFCI to
determine if the tree can be saved and mitigating measures, or if the tree should be removed.
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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 streets, and at least 10 feet of building clearance. Trees in protected forest stands and/or
buffer areas do not require pruning.
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®. The ANSI Z133.1 (2000) American National Standard - for Arboricultural
Operations - Pruning, Repairing, Maintaining, and Removing Trees, and Cutting Brush – Safety
Requirements should be observed by all tree workers.
Portions of the managed forest buffer and other retained tree stands are very dense and would
benefit from selective thinning to release higher quality dominant and codominant trees. If this
were to be done, then WFCI would need to develop the stand prescriptions and mark the stand
for the selective thinning work. There are areas that are stagnant due to high stocking.
Conclusions and Timeline for Activity
The following is a list of recommended tree protection activities and the proposed timing:
1. Prepare the final tree retention plan map showing tracts to be protected and the locations of
tree protection fencing.
2. Mark the clearing limits of the project with stakes and flagging. The marking should be
heavy so that one can see from flag to flag or stake to stake.
3. Conduct a pre-job conference with WFCI. We will inspect the tree clearing limits and mark
hazard trees and trees that would be damaged by grading on the edges.
4. Complete logging. WFCI will inspect the new stand edges after cutting, but before the
logger leaves the site. We will mark any additional trees that require removal.
5. Complete the logging.
6. Prune all edge trees that require clearances or hazard pruning.
7. Conduct a final tree inventory of retained trees to confirm the projections in this report.
Adjust required tree replacement planting if necessary.
8. Install tree protection fences - Contact WFCI to inspect the installed tree protection fences.
9. Complete land clearing. Do not remove any stumps within 10 ft. of a save tree. WFCI
should inspect these stumps to determine if it can be removed using an excavator or requires
grinding.
10. Complete grading and construct project.
11. Maintain the tree protection fences throughout grading and construction.
12. WFCI should inspect all tree tract edges after grading to identify any trees that might have
been impacted by clearing and grading. The goal is an edge of green, healthy, windfirm
trees.
13. If any unplanned construction activity will impact a ‘save’ tree, contact WFCI prior to the
impact. WFCI can assess the proposed impact and recommend cultural care, mitigation, or
removal.
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14. Conduct an annual tree evaluation to determine short-and long-term effects of site changes on
protected trees. Provide additional cultural care as needed.
Summary
Federal Way City Code (1994) requires that 25% of the significant trees in the Woodbridge
Corporate Park will need to be retained during site development. A total of 1,304 significant
trees (31%) will be retained in the 4.13 acre managed forest buffer and on 10.98 acres within the
interior of the project area. Using the 2 times bonus for the retained interior forest trees, the
minimum 25% retention requirement is exceeded by 247 trees.
Please give us a call if you have further questions.
Respectfully submitted,
Washington Forestry Consultants, Inc.
Galen M. Wright, ACF, ASCA Joshua Sharpes
ISA Bd. Certified Master Arborist PN-129BU ISA Certified Arborist/
Certified Forester No. 44 Municipal Specialist, PN-5939AM
ISA Tree Risk Assessor Qualified ISA Tree Risk Assessor Qualified
ASCA Tree and Plant Appraisal Qualified
Woodbridge Corporate Park – Updated Tree and Vegetation Retention Plan
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Attachment 1. Aerial Photo of Woodbridge Corporate Park Project Area
with Forest Cover Types (2017 King County iMap)
Project Boundary
Forest Cover Type Line
N
IV
III
II
IX
VI VII
VII
VIII
I V
I
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Attachment 2. Woodbridge Site Plan
N
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Attachment 3. Stand Summary Summaries for Entire 97.7 acre project –
Species by diameter class and stocking (total # trees/acre) for all species.
(3 pages attached)
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Attachment 4. Tree Protection Fence Detail – Locations to be
Determined
Temporary Chain Link Fence on Driven Posts
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Attachment 5. Description of Tree Evaluation Methodology
The evaluation of the tree condition on this site included the visual assessment of:
1. Live-crown ratio,
2. Lateral and terminal branch growth rates,
3. Presence of dieback in minor and major scaffold branches and twigs,
4. Foliage color,
5. Stem soundness and other structural defects,
6. Visual root collar examination,
7. Presence of insect or disease problems.
8. Windfirmness: if tree removal will expose this tree to failure.
In cases where signs of internal defect or disease were suspected, a core sample was taken to
look for stain, decay, and diameter growth rates. Also, root collars were exposed to look for the
presence of root disease.
In all cases, the overall appearance of the tree was considered relative to its ability to add value
to either an individual lot or the entire subdivision. Also, the scale of the tree and its proximity
to both proposed and existing houses was considered.
Lastly, the potential for incorporation into the project design is evaluated, as well as potential site
plan modifications that may allow otherwise removed tree(s) to be both saved and protected in
the development.
Trees that are preserved in a development must be carefully selected to make sure that they can
survive construction impacts, adapt to a new environment, and perform well in the landscape.
Healthy, vigorous trees are better able to tolerate impacts such as root injury, changes in soils
moisture regimes, and soil compaction than are low vigor trees.
Structural characteristics are also important in assessing suitability. Trees with significant decay
and other structural defects that cannot be treated are likely to fail. Such trees should not be
preserved in areas where damage to people or property could occur.
Trees that have developed in a forest stand are adapted to the close, dense conditions found in
such stands. When surrounding trees are removed during clearing and grading, the remaining
trees are exposed to extremes in wind, temperature, solar radiation, which causes sunscald, and
other influences. Young, vigorous trees with well-developed crowns are best able to adapt to
these changing site conditions.
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Attachment 6. Glossary of Forestry and Arboricultural Terminology
DBH: Diameter at Breast Height (measured 4.5 ft. above the ground line on the high side of the
tree). In Edgewood, diameter is measured at 3 ft. above the groundline.
Live Crown Ratio: Ratio of live foliage on the stem of the tree. Example: A 100’ tall tree with
40 feet of live crown would have a 40% live crown ratio. Conifers with less than 30%
live crown ratio are generally not considered to be long-term trees in forestry.
Crown: Portion of a trees stem covered by live foliage.
Crown Position: Position of the crown with respect to other trees in the stand.
Dominant Crown Position: Receives light from above and from the sides.
Codominant Crown Position: Receives light from above and some from the sides.
Intermediate Crown Position: Receives little light from above and none from the sides. Trees
tend to be slender with poor live crown ratios.
Suppressed Crown Position: Receives no light from above and none from the sides. Trees
tend to be slender with poor live crown ratios.
Woodbridge Corporate Park – Updated Tree and Vegetation Retention Plan
Washington Forestry Consultants, Inc. Page 23
Attachment 7. 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.