17-105489-Tree Retention Worksheet-04-02-2020-V13FORESTRY AND VEGETATION MANAGEMENT SPECIALISTS
WFCI
3601943-1 723
FAX 3601943-4 1 28
1919 Yelm Hwy SE, Suite C
Olympia, WA 98501
URBANIRURAL FORESTRY TREE APPRAISAL HAZARD TREE ANALYSIS
RIGHT-OF-WAYS VEGETATION MANAGEMENT ENVIRONMENTAL STUDIES CONTRACT FORESTERS
Member of International Society of Arboriculture and Society of American Foresters
-Revised 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: February 18, 2020
Introduction
The project proponent is planning to construct 3 commercial buildings on 135.6 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 11 forested cover types and 1 non-forest type
(meadow).
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
Woodbridge Corporate Park - Tree and Vegetation Retention Plan
Washington Forestry Consultants, Inc. Page 2
significant trees by the 1994 ordinance. The forest inventory data was processed using
SuperAce®, a forest inventory processing software program.
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 5 parcels totaling 135.6 acres. Topography is mostly flat
to gently rolling, sloping slightly to the northeast into North Lake. 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 undeveloped forest and North Lake.
Many small wetlands occur sporadically on the west side of the project area near Interstate 5 and
more contiguously on the east side near North Lake.
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 one
soil type in the project area - 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.
Woodbridge Corporate Park - Tree and Vegetation Retention Plan
Washington Forestry Consultants, Inc. Page 3
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.
Figure 1. Soils Map of Woodbridge Corporate Park Project Area
Project Area Boundary
Ag - Alderwood gravelly sandy loam - 98.4%
Existing Tree Conditions
There are 12 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 30.65 acre type includes the developed portion of the project area near
the existing large office building. The 9.5 acre treed portion of this cover type includes the forested
islands in the parking area.
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),
N
Ag
Woodbridge Corporate Park - Tree and Vegetation Retention Plan
Washington Forestry Consultants, Inc. Page 4
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 (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 approximately 87 Trees per Acre (TPA),
or 810 total significant trees in the 9.5 forested acres of the total 30.65-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’ 33 316
Woodbridge Corporate Park - Tree and Vegetation Retention Plan
Washington Forestry Consultants, Inc. Page 5
Species DBH Range (in.) Condition Range
Total Trees Per
Acre
Total # Healthy
Significant Trees
Total 12 - 57 ‘Poor’ - ‘Good’ 87 805
*Not Considered Significant under 1994 Definition
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 trees per acre and 451 significant trees 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 30 trees per acre and 35 significant trees 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.
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
Woodbridge Corporate Park - Tree and Vegetation Retention Plan
Washington Forestry Consultants, Inc. Page 6
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 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.
Woodbridge Corporate Park - Tree and Vegetation Retention Plan
Washington Forestry Consultants, Inc. Page 7
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 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.
Woodbridge Corporate Park - Tree and Vegetation Retention Plan
Washington Forestry Consultants, Inc. Page 8
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.
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
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 162 trees per acre and 536 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.
Woodbridge Corporate Park - Tree and Vegetation Retention Plan
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.
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’ 75 490
Total 12 - 42 ‘Poor’ - ‘Good’ 82 535
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 27 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.
Woodbridge Corporate Park - Tree and Vegetation Retention Plan
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.
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’ 7 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’ 27 106
*Not Considered Significant under 1994 Definition
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.
Woodbridge Corporate Park - Tree and Vegetation Retention Plan
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).
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
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.
Woodbridge Corporate Park - 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.
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
Forest Cover Type X. -- Type X is a mature stand of Douglas-fir and bigleaf maple with some
western redcedar, western hemlock and red alder in the understory. Tree size ranges from 12 to 57
inches DBH. There are 37 trees per acre and 440 healthy, significant trees over the 10.25-acre
cover type. Tree condition ranges from ‘Poor’ to ‘Good,’ with most trees described as being in
‘Fair’ condition or better.
Woodbridge Corporate Park - Tree and Vegetation Retention Plan
Washington Forestry Consultants, Inc. Page 13
Photo 10. View of trees in Cover Type X
Understory vegetation 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, English holly (Ilex aquifolium), grasses, and broadleaved weeds.
Table 10. Summary of Trees in Cover Type X
Species DBH Range (in.) Condition Range
Total Trees Per
Acre
Total # Healthy
Significant Trees
Douglas-fir 12 - 52 ‘Fair’ - ‘Good’ 8 82
Western Redcedar 12 - 57 ‘Fair’ - ‘Good’ 15 151
Bigleaf Maple* 16 - 28 ‘Poor’ - ‘Fair’ 6 0
Red Alder* 15 - 28 ‘Fair’ - ‘Good’ 7 0
Black Cottonwood* 12 - 20 ‘Fair’ - ‘Good’ 1 0
Total 12 - 57 ‘Poor’ - ‘Good’ 37 440
*Not Considered Significant under 1994 Definition
Forest Cover Type XI. -- Type XI is a high-density stand of low-quality, native deciduous trees
including Oregon ash and black cottonwood. Some Douglas-fir trees also occur in this cover type,
but are widely scattered and mostly in ‘Poor’ condition due to suppression. Tree size is generally
small and ranges from 8 to 26 inches DBH. There are 168 trees per acre with no significant trees
over the 6.5-acre cover type. Tree condition ranges from ‘Dead’ to ‘Fair,’ with most trees
described as being in ‘Poor’ condition or worse.
Table 11. Summary of Trees in Cover Type XI
Species DBH Range (in.) Condition Range
Total Trees Per
Acre
Total # Healthy
Significant Trees
Douglas-fir 14 - 26 ‘Poor’ 3 0
Black Cottonwood* 12 - 20 ‘Dead’ - ‘Fair’ 114 0
Ash 8 - 9 ‘Poor’ - ‘Fair’ 51 0
Total 8 - 26 ‘Dead’ - ‘Fair’ 168 0
*Not Considered Significant under 1994 Definition
Woodbridge Corporate Park - Tree and Vegetation Retention Plan
Washington Forestry Consultants, Inc. Page 14
Phot o 11. View of trees in Cover Type XI
Understory vegetation is dense and consists of mostly native plants, tree saplings, and some non-
native, invasive species. Native species include salmonberry, western hazel, Indian-plum, salal,
trailing blackberry, snowberry (Symphoricarpos alba), prostrate Oregon-grape, sword fern, and
bracken fern (Pteridium aquilinum). Invasive plants include English ivy (Hedera helix), blackberry
(Rubus armeniacus), grasses, and broadleaved weeds.
Forest Cover Type XII. -- Type XII is an open field on the southern end of the project area. Aside
from a few deciduous trees in a wetland area on the very southern end, there are no trees in this
cover type. Vegetation consists mostly of grass.
Summary of All Cover Types
A total of about 99.1 acres of the 135.6-acre project area are forested by 12 distinct forest cover
types. The following table summarizes all cover types and significant trees in the Woodbridge
Corporate Park project area.
Table 12. Summary of all Cover Types in the Woodbridge Corporate Park Project Area
Species
DBH
Range
(in.) Condition Range
Total Trees Per
Acre
Total # Healthy
Significant Trees
Douglas-fir 12 - 52 ‘Dead’ - ‘Good’ 29.67 2,729
Western Redcedar 12 - 57 ‘Poor’ - ‘Good’ 8.04 658
Western Hemlock 18 - 56 ‘Poor’ - ‘Good’ 0.98 92
Oregon Ash 8 - 10 ‘Poor’ - ‘Fair’ 3.17 0
Other Conifer 12 - 24 ‘Poor’ - ‘Good’ 4.85 81
Other Hardwood** 12 - 40 ‘Poor’ - ‘Good’ 10.51 1,105
Bigleaf Maple* 12 - 53 ‘Poor’ - ‘Good’ 2.23 0
Red Alder* 12 - 28 ‘Very Poor’ - ‘Good’ 5.10 0
Black Cottonwood* 12 - 69 ‘Very Poor’ - ‘Good’ 9.90 0
Total 8 - 69 ‘Dead’ - ‘Good’ 74.45 4,665
*Not Considered Significant under 1994 Definition
**Includes non-native Ash Trees
Woodbridge Corporate Park - Tree and Vegetation Retention Plan
Washington Forestry Consultants, Inc. Page 15
Discussion
The 1994 Federal Way City Code requires 25% of the significant trees to be retained on
commercial projects. Current site plans leave much of Cover Types X, XI, XII and portions of
Cover Type IV undeveloped. The following is a summary of our tree retention calculations.
Total # of Significant Trees in Buildable Area of Project 4,665
Required Tree Retention (25% x 4,665) 1,166
Healthy Significant Perimeter Landscape Trees 584
Healthy Significant Trees in Managed Forest (1,096 x 2) 2,192
Total Healthy Significant Trees Retained on Site 2,776
Surplus of Tree Retention Requirement +1,610
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 1,096 interior trees count as 2,192 trees when calculating tree retention.
By retaining 1,680 healthy significant trees, which count as 2,776 healthy (60%) significant trees
in the project area, this plan exceeds the 25% minimum retention requirement described in Federal
Way City Code (1994) by 35%. An additional 382 healthy trees, smaller than 12”, are also being
retained.
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.
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 do not require
pruning.
Woodbridge Corporate Park - Tree and Vegetation Retention Plan
Washington Forestry Consultants, Inc. Page 16
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 tree tracts 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. Install tree protection fences - Contact WFCI to inspect the installed tree protection fences.
8. 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.
9. Complete grading and construct project.
10. Maintain the tree protection fences throughout grading and construction.
11. 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.
12. 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.
13. Conduct an annual tree evaluation to determine short-and long-term effects of site changes on
protected trees. Provide additional cultural care as needed.
Woodbridge Corporate Park - Tree and Vegetation Retention Plan
Washington Forestry Consultants, Inc. Page 17
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 1,680 significant trees,
which count as 2,192 (60%) will be retained in perimeter tree tracts and managed forest areas. By
counting healthy significant trees in managed areas within the interior portion of the site as 2 trees,
the minimum 25% retention requirement is exceeded by 1,610 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
ASCA Tree and Plant Appraisal Qualified
Other Contributors: Riley Stark - Professional Forester,
ISA Board Certified Master Arborist, Municipal Specialist #PN-7780
Woodbridge Corporate Park - Tree and Vegetation Retention Plan
Washington Forestry Consultants, Inc. Page 18
Attachment 1. Aerial Photo of Woodbridge Corporate Park Project Area
with Extent of Forest Cover Types Indicated
(2017 King County iMap)
Property Boundary
Forest Cover Type Line
XII
N
IV III
II
IX
VI VII
VII
XI
X
VIII
I V
Woodbridge Corporate Park - Tree and Vegetation Retention Plan
Washington Forestry Consultants, Inc. Page 19
Attachment 2. Woodbridge Site Plan
N
Woodbridge Corporate Park - Tree and Vegetation Retention Plan
Washington Forestry Consultants, Inc. Page 20
Attachment 3. Stand Summary Summaries for Forested Acres of Project
–Species by Diameter Class and Stocking (Trees/Acre).
(3 pages attached)
Acres
Project
105.10
WDBRIDGE Time: 2:59:24PM
Date:6/17/2019
Page 1Stand Table Summary
PSTNDSUM
T21N R04E S16 Ty0001
THRU
T21N R04E S16 Ty0012
TC
Federal Way Campus LLC
Grown Year:
T o t a l s
Sample
Trees Tons
S
T AcreSpc MBFCunits
Net
Bd.Ft.
Acre
Net
Cu.Ft.Tons/
Acre
Average Log
Net
Bd.Ft.
Net
Cu.Ft.
Logs
Acre
BA/
Acre
Trees/
Acre
Av
Tot
Ht16'DBH
FF BA/
16 43 .402 .56 1 24BM
17 62 .332 .52 1 28BM
21 42 .233 .56 1 22BM
24 82 .783 2.46 2 49
BM
28 88 .288 1.23 1 53BM
32 80 .046 .26 1 38BM
38 43 .130 1.03 1 20BM
53 79 .017 .26 1 36BM
BM 9 66 37 2.232Totals 6.88
6 98 3.150 .62 1 17CW
12 98 1.575 1.24 2 17CW
13 98 .671 .62 1 17CW
14 98 1.157 1.24 2 17CW
20 62 .283 .62 1 27CW
22 74 .602 1.59 2 34CW
24 76 .654 2.06 2 35CW
26 62 .152 .56 1 26CW
29 78 .400 1.84 2 37CW
32 80 .496 2.77 4 40CW
33 42 .173 1.03 1 20CW
36 82 .079 .56 1 42CW
37 88 .165 1.23 1 52CW
39 73 .075 .62 1 31CW
48 90 .057 .71 1 62CW
50 88 .090 1.23 1 51CW
56 86 .060 1.03 1 46CW
59 90 .035 .67 1 62CW
69 62 .033 .86 1 25CW
CW 27 90 23 9.908Totals 21.07
11 98 1.689 1.11 2 17DF
12 54 1.090 .86 1 26DF
13 78 10.499 9.68 12 42DF
14 63 3.204 3.43 4 28DF
15 84 .426 .52 1 60DF
16 74 2.712 3.79 5 43
DF
17 67 .543 .86 1 28DF
18 74 1.865 3.30 6 37DF
19 84 1.073 2.11 4 56DF
20 87 .480 1.05 2 71DF
21 88 .218 .52 1 73DF
22 88 .198 .52 1 78
DF
23 88 .363 1.05 2 78DF
24 86 .345 1.08 2 66DF
25 84 .152 .52 2 52DF
26 81 .946 3.49 5 63DF
28 88 .508 2.17 3 73DF
29 88 .170 .78 2 78
DF
30 88 .107 .52 1 86DF
31 88 .414 2.17 4 88DF
32 89 .202 1.13 2 93DF
33 88 .088 .52 1 102DF
34 89 .278 1.75 2 90DF
Acres
Project
105.10
WDBRIDGE Time: 2:59:24PM
Date:6/17/2019
Page 2Stand Table Summary
PSTNDSUM
T21N R04E S16 Ty0001
THRU
T21N R04E S16 Ty0012
TC
Federal Way Campus LLC
Grown Year:
T o t a l s
Sample
Trees Tons
S
T AcreSpc MBFCunits
Net
Bd.Ft.
Acre
Net
Cu.Ft.Tons/
Acre
Average Log
Net
Bd.Ft.
Net
Cu.Ft.
Logs
Acre
BA/
Acre
Trees/
Acre
Av
Tot
Ht16'DBH
FF BA/
36 88 .158 1.11 2 79DF
37 87 .166 1.24 2 76DF
38 88 .109 .86 2 66DF
40 89 .418 3.65 4 100
DF
41 90 .191 1.75 2 106DF
43 89 .244 2.46 2 106DF
44 89 .068 .71 1 84DF
45 90 .111 1.23 1 116DF
46 89 .045 .52 1 100DF
47 89 .102 1.23 1 100
DF
52 90 .083 1.23 1 104DF
DF 85 78 47 29.268Totals 58.94
8 99 1.772 .62 1 17OA
9 98 1.400 .62 1 17OA
OA 2 99 17 3.172Totals 1.24
12 92 2.726 2.14 3 22OC
13 64 1.209 1.11 2 23
OC
15 67 .421 .52 2 30OC
23 78 .429 1.24 1 38OC
28 69 .060 .26 1 27OC
OC 9 81 24 4.845Totals 5.27
9 98 .585 .26 1 17OH
11 31 .391 .26 1 26OH
12 99 .329 .26 1 17OH
13 68 2.500 2.30 3 27OH
14 59 3.312 3.54 4 29OH
15 72 2.337 2.87 5 24OH
17 62 .513 .81 1 28OH
18 70 .292 .52 2 20OH
19 73 .131 .26 1 33OH
20 43 .118 .26 1 22OH
OH 20 67 26 10.508Totals 11.33
13 73 .568 .52 1 36RA
14 88 .564 .60 1 60RA
15 60 2.468 3.03 4 31RA
16 62 .511 .71 1 28
RA
17 78 .423 .67 1 40RA
20 62 .327 .71 1 27RA
23 73 .247 .71 1 32RA
RA 10 67 35 5.108Totals 6.96
10 99 .474 .26 1 17RC
12 85 1.896 1.49 2 21RC
14 82 .242 .26 1 18RC
16 81 .185 .26 1 18RC
17 82 .164 .26 1 21RC
19 81 .743 1.46 3 36RC
22 80 .228 .60 1 44RC
23 82 .090 .26 1 26RC
24 81 .082 .26 1 44RC
Acres
Project
105.10
WDBRIDGE Time: 2:59:24PM
Date:6/17/2019
Page 3Stand Table Summary
PSTNDSUM
T21N R04E S16 Ty0001
THRU
T21N R04E S16 Ty0012
TC
Federal Way Campus LLC
Grown Year:
T o t a l s
Sample
Trees Tons
S
T AcreSpc MBFCunits
Net
Bd.Ft.
Acre
Net
Cu.Ft.Tons/
Acre
Average Log
Net
Bd.Ft.
Net
Cu.Ft.
Logs
Acre
BA/
Acre
Trees/
Acre
Av
Tot
Ht16'DBH
FF BA/
25 80 .722 2.46 2 61RC
26 80 .722 2.66 6 45RC
27 81 .065 .26 1 37RC
28 80 .141 .60 1 54
RC
31 81 .214 1.12 3 39RC
32 81 .262 1.46 3 56RC
34 80 .191 1.21 2 51RC
36 81 .037 .26 1 39RC
37 81 .115 .86 2 60RC
38 80 .194 1.53 3 62
RC
40 81 .220 1.92 3 58RC
41 80 .089 .82 2 57RC
42 81 .152 1.46 3 53RC
43 81 .148 1.49 2 59RC
44 80 .174 1.83 2 69RC
45 80 .109 1.21 2 69
RC
46 80 .052 .60 1 63RC
47 80 .102 1.23 1 73RC
49 81 .046 .60 1 63RC
52 80 .041 .60 1 57RC
53 80 .080 1.23 1 62RC
54 81 .016 .26 1 43
RC
57 80 .015 .26 1 41RC
62 81 .029 .60 1 67RC
RC 58 83 40 8.038Totals 31.64
15 70 .491 .60 1 28WH
17 84 .382 .60 1 45WH
33 88 .101 .60 1 53WH
WH 3 77 37 .975Totals 1.81
Totals 223 79 36 145.14 74.053
Woodbridge Corporate Park - Tree and Vegetation Retention Plan
Washington Forestry Consultants, Inc. Page 21
Attachment 4. Tree Protection Fence Detail – Locations to be Determined
Temporary Chain Link Fence on Driven Posts
Woodbridge Corporate Park - Tree and Vegetation Retention Plan
Washington Forestry Consultants, Inc. Page 22
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.
Woodbridge Corporate Park - Tree and Vegetation Retention Plan
Washington Forestry Consultants, Inc. Page 23
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 - Tree and Vegetation Retention Plan
Washington Forestry Consultants, Inc. Page 24
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.