014 Managed Forest Buffer Management Plan, Greenline Building B, 6-26-2018
MANAGED FOREST BUFFER
MANAGEMENT PLAN
at the
GREENLINE BUILDING B SITE
Weyerhaeuser Way South
Federal Way, WA 98003
File #17-104236-UP & 17-104237-SE
Revised June 26, 2018
August 24, 2017
PREPARED FOR:
Federal Way Campus, LLC
11100 Santa Monica Boulevard
Los Angeles, CA 90025
PREPARED BY:
GILLES CONSULTING
Brian K. Gilles, Consulting Arborist
ISA Certified Arborist # PN-0260A
ASCA Registered Consulting Arborist # RCA-418
ISA TRAQ Qualified
ISA TRAQ Certified Instructor
Managed Forest Buffer Management Plan for the Greenline Building “B” Site
Weyerhaeuser Way South, Federal Way, WA 98003
Gilles Consulting
June 26, 2018
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This Managed Forest Buffer Maintenance Management Plan is adopted by:
Federal Way Campus, LLC
111000 Santa Monica Boulevard
# 850
Los Angeles, CA 90025
Signature and Title Date
And,
The City of Federal Way
Brian Davis
Community Development Director
33325 8th Avenue South
Federal Way, WA 98003
Signature and Title Date
Managed Forest Buffer Management Plan for the Greenline Building “B” Site
Weyerhaeuser Way South, Federal Way, WA 98003
Gilles Consulting
June 26, 2018
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CONTENTS
INTRODUCTION............................................................................................................. 4
Evaluation of Trees & Status Determination .................................................................. 4
Risk Assessment ............................................................................................................. 5
INVENTORY OF THE FOREST TODAY .................................................................... 9
Additional Testing .......................................................................................................... 9
CURRENT VEGETATIVE INVENTORY .................................................................... 9
Tall Trees Observed: ....................................................................................................... 9
Small Native Trees/Small Shrubs Observed ................................................................. 10
Low Growing Native Shrubs and Ground Covers Observed: ...................................... 10
Invasive Species Observed: .......................................................................................... 10
Landscape Plant Species ............................................................................................... 10
Summary of the Managed Forest Buffer Trees ............................................................. 11
KEY PLAN ELEMENTS ............................................................................................... 11
Invasive Species Control............................................................................................... 11
Trees Protection Measures During Construction .......................................................... 13
General Maintenance Plan ............................................................................................ 14
CONCLUSIONS AND RECOMMENDATIONS ........................................................ 14
Recommended Plant Pallet ........................................................................................... 15
WAIVER OF LIABILITY ............................................................................................. 15
ATTACHMENTS ........................................................................................................... 17
Managed Forest Buffer Management Plan for the Greenline Building “B” Site
Weyerhaeuser Way South, Federal Way, WA 98003
Gilles Consulting
June 26, 2018
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EXECUTIVE SUMMARY
This plan is to manage the Managed Forest Buffer (MFB) that runs parallel to
Weyerhaeuser Way South on the Greenline Building “B” project property into the future.
There is a proposal to convert the 16-acre parcel into a large commercial project with
associated parking lots, drivelanes, loading docks, and landscape features.
This plan has been drafted to meet the “letter of the law” as well as the “spirit of the law”
as laid out in the Weyerhaeuser Company Concomitant Pre-Annexation Developer
Agreement (“Agreement”) dated August 23, 1994, as well as the 1994 Federal Way City
Code (FWCC).
As such, the following pages contain information on current conditions, risk assessment
of the trees, tree protection measures during construction, long term management goals,
standards of care, and re-planting plans.
INTRODUCTION
Eric LaBrie, President of ESM Consulting Engineers, on behalf of the Federal Way
Campus, LLC, contracted with Gilles Consulting to develop this Management Plan for
the Managed Forest Buffer on the Greenline Building B Project site located on King
County Parcel Number 614260-0200 Through the Agreement between the Weyerhaeuser
Company and the City of Federal Way, managed forest buffers were required to be
created, managed, and maintained. The Agreement spelled out where the buffers were to
be located and how they were to be managed.
Because it is a ‘concomitant’ agreement, the provisions of the Agreement carry forward
to new owners and new uses of the property. This Agreement is tied to the 1994 FWCC.
This Forest Management Plan brings together the key elements of these documents in
how it is written and how it is expected to be carried out.
SCOPE AND METHODOLOGY
Evaluation of Trees & Status Determination
First, an inventory of the existing vegetation within the buffer was conducted. This
included documenting the species present, their relative size, and their condition. Each
tree was tagged with a unique number and its trunk measured at 4.5 feet above the
average ground level.
Following the 1994 FWCC Section 22-1568(c)(6), we used the definition of a significant
tree to grade the status of each tree encountered. As defined in 1994 FWCC Sec. 22-
1568(b) a Significant Tree is a tree that is:
1) Twelve inches in diameter or 37 inches in circumference measured four and one-
half feet above the ground; and
Managed Forest Buffer Management Plan for the Greenline Building “B” Site
Weyerhaeuser Way South, Federal Way, WA 98003
Gilles Consulting
June 26, 2018
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2) In good health; and
3) Not detrimental to the community (e.g. is not diseased, dying, or likely of falling
into public open space or right-of-way, etc.) or obscuring safe sight distance
requirements. Significant trees shall not include red alder, cottonwood, poplar or
big leaf maple.
Using Sec. (c) Standards, calculations for tree retention were calculated and a Tree
Retention Plan has been included in the permit documents not as a part of the MFB Plan.
This is because all of the trees in the MFB are to be retained—unless they pose a threat to
life and property. These retained trees shall be protected as defined in the Tree
Protection Measures section below.
Trees were also evaluated for risk to determine whether or not any of the trees pose an
unacceptable level of risk to life and property. The goal was to identify any potential
hazard trees and manage them down to a safe level during clearing and grading phases of
the project. We followed the protocol of the International Society of Arboriculture
known as Tree Risk Assessment Qualification, TRAQ. This is a scientifically based
process that includes a roots to shoots evaluation of each tree to determine health,
structural stability, and likelihood of failure. Trees were then rated as Significant or Non-
Significant based upon criteria a – c above and the size of their trunk at 4.5 feet as
measured with a diameter tape measure.
Risk Assessment
Tree Risk Assessment must be taken seriously on this project and all of the Campus
development projects. This is due to the physiology of the trees themselves, their growth
in dense stands, the soils, and the large storms that descend upon the region irregularly.
When trees grow in a forest such as this, they depend on the trees around them to buffer
them from the wind and other storm impacts. This results in a different physically
structured tree than the same species of the same age growing in an open setting such as a
field, a park, or a pasture.
Trees growing in a dense forest are tall and skinny. They do not have broadly tapered
bases or large buttress roots. They do not need them due to the buffering effect of the
forest as a whole. Their job is to grow tall and fast to catch sunlight. If they do not keep
up with the neighboring trees, they get shaded out and slowly decline and die. Therefore,
their internal resources are spent on height growth.
This is relevant and important in that, when dense forest trees are suddenly opened to the
wind and storm elements, by clearing of adjacent trees, they are instantly vulnerable to
windthrow in severe weather. This is because, as noted above, they do not have adequate
structure in their lower trunks and buttress roots. This can be seen when driving forested
lands in the northwest and looking at wind-thrown trees at the edges of recent clear cuts.
Foresters have known this for over 100 years and have a term for it. They call it, “New
Edge.” New Edge refers to the trees on the edge of a recent clear-cut. There can be a
Managed Forest Buffer Management Plan for the Greenline Building “B” Site
Weyerhaeuser Way South, Federal Way, WA 98003
Gilles Consulting
June 26, 2018
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high percentage of tree failures near the ‘new edge’ created by the clearing/logging of
trees in a dense forest due to the growth characteristics noted above. It can take a tree or
line of trees along a newly cleared edge many years to develop larger and roots and lower
trunks to withstand large storm loads.
Soils and saturated soils also play a huge role in tree risk assessment. The region is
known to have areas of hard pan or clay deposits below the surface. Water can build up
on top of these impenetrable layers and restrict roots from penetrating deep. This can
predispose a tree to fail if it is growing over one of these dense layers and the soil is
saturated and a storm overloads the strength of the roots and soil.
Risk Management Goal:
o Minimize or eliminate any injury, death, or property damage due to newly
exposed tall evergreen trees that remain in the MFB.
Risk Management Action:
o Preliminary Risk Assessment:
In the development of this document, trees in the MFB were
assessed for risk.
Targets were identified as people using the right-of-way, the
construction workers building the new facilities, the proposed new
facilities, and the people using the new facilities.
Trees that were found to have an unacceptable level of risk are
recommended for management actions during the clearing and
grading process of the project.
o During Construction:
The Forest Manager shall be on site during the clearing and
grading process to perform a risk assessment of the trees slated to
remain in the MFB—the “new edge trees.”
This is important for one specific reason. As a forest is
cleared many more items become visible that were not
visible in the dense forest. These newly seen items may
impact the wind firmness and stability of the new edge
trees.
The Forest Manager shall use current International Society of
Arboriculture Best Management Practices for Tree Risk
Assessment to systematically determine whether any of the trees
slated for retention pose an unacceptable level of risk.
Working with the clearing and grading contractor, the owner’s
representative, the surveyor, and property manager, the
environmental consultant, the Forest Manager will recommend
actions to be taken on individual trees to reduce the risk of injury,
death, or property damage.
Management options will begin with pruning and removal
will be the last option. A parallel option will be the
Managed Forest Buffer Management Plan for the Greenline Building “B” Site
Weyerhaeuser Way South, Federal Way, WA 98003
Gilles Consulting
June 26, 2018
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creation of Habitat Trees, Nurse Logs, and Brush Piles.
These are three critically important elements in urban and
suburban forest that benefit desirable wildlife such as song
birds and frogs.
Please refer to Attachment 2, Creation and Benefits of
Habitat Trees, Nurse Logs, and Brush Piles below for
important information concerning these vital forest
elements.
o Ongoing Risk Assessment:
The Challenge:
Trees are vulnerable to windthrow for as many as 10 years
after the creation of a ‘new edge.’ It can take that long for
the new edge trees to grow sufficient root structures and to
broaden the bases of the trunks to withstand the stresses of
wind and storms.
Actions:
The Forest Manager shall use current International Society
of Arboriculture Best Management Practices for Tree Risk
Assessment to systematically determine whether any of the
trees slated for retention pose an unacceptable level of risk.
Frequency:
o The Forest Manager will respond to specific
requests from property occupants/staff, landscape
maintenance staff, or the public to assess the level
of risk for specific trees.
o For the first four years:
The Forest Manager will walk site every
summer and perform a Level I Risk
Assessment of the trees in the MFB.
Trees identified as having defects or health
issues will be given a Level II Risk
Assessment.
Please refer to Attachment 3, Tree
Risk Assessment Protocol for more
detailed information.
This work must be done in the summer so
that any trees declared a risk to life and
property can be properly managed prior to
the onset of the storm season.
o No Risk Assessment will be done in year five.
o Beginning in year six, Risk Assessments shall be
done once every two years; or if called in to look at
Managed Forest Buffer Management Plan for the Greenline Building “B” Site
Weyerhaeuser Way South, Federal Way, WA 98003
Gilles Consulting
June 26, 2018
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specific trees by the owner’s representative or the
property manager to evaluate specific trees or
groups of trees of concern.
The Forest Manager will walk the property
and perform a Risk Assessment on the trees
within the MFB.
Working with the owner’s representative and property
manager, the Forest Manager will recommend actions to be
taken on individual trees to reduce the risk of injury, death,
or property damage.
o All trees deemed a potential hazard do not need to
be cut down completely.
They can be converted into Habitat
Trees/Wildlife Snags, Nurse Logs, and
Brush piles.
These three features are key elements in a
healthy urban/suburban environment. They
are critical to dozens of desirable wildlife
species—especially songbirds, frogs and
other amphibians.
Please refer to Attachment 3, The Benefit of
Habitat Trees, Nurse Logs, and Brush Piles
in Urban and Suburban Areas for important
information on these key items.
While no one can predict with absolute certainty which
trees will or will not fail, we can, by using this scientific
process, assess which trees are most likely to fail and take
appropriate action to minimize injury and damage.
Photo #1: Photo from the north end of the Managed Forest Buffer, typical.
Managed Forest Buffer Management Plan for the Greenline Building “B” Site
Weyerhaeuser Way South, Federal Way, WA 98003
Gilles Consulting
June 26, 2018
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Photo #2: Photo from the south end of the Managed Forest Buffer, typical.
INVENTORY OF THE FOREST TODAY
The MFB is today a combination of native trees, landscape trees, and native shrubs
typical of lowland Puget Sound. An existing sewer easement and gravel trail are located
within the MFB, and can be observed in Photo 1 and 2 above. Areas adjacent to the
easement are maintained with lawn areas and small deciduous trees, such as red alder.
Additional Testing
The trees all presented signs and/or symptoms that were readily discernible using the
visual tree evaluation system. These signs and/or symptoms indicate extensive internal
decay and/or structural defects in some trees and solid trunks and lack of disease in
others. Therefore, no additional tests were performed during this site visit.
CURRENT VEGETATIVE INVENTORY
The present plant community in the MFB is a combination of native plant and shrubs
typical of lowland Puget Sound native forests and several landscape species that were
introduced in years past. Plants observed in the summer and winter of 2016 included:
Tall Trees Observed:
Big Leaf Maple, Acer macrophyllum
Cascara, Rhamnus purshiana
Douglas Fir, Pseudotsuga menziesii
Oregon Ash, Fraxinus latifolia
Pacific Madrone, Arbutus menziesii
Pacific Willow, Salix lasiandra
Paperbark Birch, Betula papyrifera
Red Alder, Alnus rubra
Managed Forest Buffer Management Plan for the Greenline Building “B” Site
Weyerhaeuser Way South, Federal Way, WA 98003
Gilles Consulting
June 26, 2018
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Western Hemlock, Tsuga heterophylla
Western Red Cedar, Thuja plicata
The trees were rated on a scale from Dead, to Dying, to Poor, to Fair, to Good, to
Very Good, to Excellent.
As noted above, the shrub and ground cover layers consisted of plants typical of lowland
Puget Sound that include:
Small Native Trees/Small Shrubs Observed
Vine Maple, Acer circinatum
Western Hazelnut, Corylus cornuta
Indian Plum, Oemleria cerasiformis
They are all in Fair to Excellent Condition.
Low Growing Native Shrubs and Ground Covers Observed:
Salal, Gaultheria shallon
Trailing Blackberry, Rubus ursinus
Snowberry, Symphoricarpos alba
Oregon Grape, Mahonia nervosa
Bracken Fern, Pteridium aquilinum
They are all in Fair to Very Good Condition.
Invasive Species Observed:
Himalayan Blackberry, Rubus armeniacus
English Ivy, Hedera helix
English Holly, Ilex aquifolium.
While small in number they appear healthy at this time.
Landscape Plant Species
Landscape Plants are those plants that are not native to lowland Puget Sound, (at or
before European/American colonization), and were intentionally installed by previous
developers, grounds managers, gardeners, maintenance staff, and forest managers. Some
of the plants are native to other areas of Washington and the Pacific Northwest but not to
this portion of Washington. By definition, they are non-native. Landscape Plants
observed within the MFB include:
American Beech, Fagus grandifolia
Flowering Cherry, Prunus sp.
European Mountain Ash, Sorbus aucuparia
Japanese Maple, Acer palmatum
Norway Maple, Acer plantanoides
Managed Forest Buffer Management Plan for the Greenline Building “B” Site
Weyerhaeuser Way South, Federal Way, WA 98003
Gilles Consulting
June 26, 2018
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Giant Sequoia, Sequioadendron giganteum
Green Ash, Fraxinus pennsylvanica
Unknown Deciduous
Summary of the Managed Forest Buffer Trees
A complete data set of all trees identified within both the Greenline Building A and B
projects can be found in the Tree Data for 32 Acre Site dated 26 June 2018. There were
527 significant trees documented on the parcel; 80 are in the MFB. They can be
summarized in the following ways:
Status:
o There are 80 trees that meet the 1994 FWCC definition of Significant Tree
in the MFB.
o There are a total of 527 Significant Trees on the parcel.
Health:
o There are a few trees that were rated as Poor, Dying, or Dead on the
parcel.
These are grouped together as Non-Viable and are by definition
Non-Significant.
o The remaining 607 trees in the MFB and interior project site that have a
status of Significant Tree, have a condition rating of Fair, Good, Very
Good, or Excellent.
Retention:
o All trees, both significant and non-significant, will be retained in the MFB.
KEY PLAN ELEMENTS
Invasive Species Control
As noted above, King County has an active Noxious Weed Board who are charged by
law to control invasive species within King County. These laws are there “ . . . to protect
local agriculture, [think plants that deny crop growth such as Canada Thistle], native
species and ecosystems, recreation, [think Milfoil clogging boat launches and swimming
beaches at area lakes], residents, [think plants that cause serious poison or allergic effects
for people, livestock, or pets], and our current way of life.” (Quoted from the King
County Noxious Weed Board website with minor editorial comments.)
Definitions used by the King County Noxious Weed Control Board include:
Noxious Weed:
o A non-native plant that when established is highly destructive,
competitive, or difficult to control.
Control:
Managed Forest Buffer Management Plan for the Greenline Building “B” Site
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Gilles Consulting
June 26, 2018
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o In a given year, prevent all seed production and dispersal of all
propagative parts capable of forming new plants.
Eradicate:
o Completely eliminate a noxious weed within an area of infestation.
King County uses the following classifications:
Regulated Class A Weeds:
o These weeds are the highest priority in the state due to their significant
potential impact and limited distribution.
o Property owners throughout Washington are required to eradicate Class A
weeds.
Regulated Class B Weeds:
o Class B weeds are regulated in counties where they are limited in
distribution or where they are a local priority. King County has
designated a list of such plants.
o Property owners in King County are required to control these plant
species.
Regulated Class C Weeds:
o Class C weeds are generally widespread, but may be selected on a local
level. The King County Weed Board has a designated list of such plants.
o Property owners in King County are not required to control these plant
species. However, control is recommended and property owners are
restricted from purchasing and installing them.
Non-Regulated Class C Noxious Weeds:
o There is a list of plat species developed by the State Weed Board and
adopted by the King County Weed Control Board designating these plants.
o They are generally plants that negatively impact the county but are already
widespread.
o Property owners in King County are not required to control these species,
but control is recommended where feasible.
o Himalayan Blackberry and English Ivy are on this list.
Class C Weeds of Concern:
o The King County Weed Control Board recognizes these species as non-
native and invasive.
o Control or containment of existing populations is recommended and the
Board discourages new plantings of species on this list.
o English Holly is on this list.
Please refer to the King County Weed Control Board website for additional
information:
o http://www.kingcounty.gov/services/environment/animals-and-
plants/noxious-weeds/weed-control-board.aspx
Managed Forest Buffer Management Plan for the Greenline Building “B” Site
Weyerhaeuser Way South, Federal Way, WA 98003
Gilles Consulting
June 26, 2018
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The maintenance plan below includes the removal of all noxious weeds including
Himalayan Blackberries, English Laurel, English Holly, and English Ivy. And, any other
species on the King County Noxious Weed List that invade the MFB in the future. They
will be replaced with plants from the Native Plant Replacement Pallet below.
Trees Protection Measures During Construction
While the development team is committed to maintaining the integrity of the MFB,
maximizing the development potential for the property is also important. Therefore, the
trees right along the edge of the MFB, the “new edge trees,” will be impacted by the
grading required to create a functional facility. This includes the construction of a
retaining wall and filling the area to create as safe of a working environment and parking
area as is reasonable.
To manage this, the trees on the edge, where the MFB meets clearing, grading, and
development, will need to be dealt with on a case by case basis depending upon their size,
condition, and proximity to the edge of the MFB and the retaining wall. Retention of the
trees will depend upon whether or not an adequate critical root zone can be maintained in
order for the tree to survive long-term and whether or not large roots need to be severed
that may leave the tree unstable and vulnerable to windthrow. The Forest Manager will
determine whether or not an adequate root zone can or cannot be maintained. Based
upon this determination, individual trees will be recommended for reduction, removal, or
replacement. This decision will be made by the Forest Manager on a case by case basis
in consultation with the general contractor, the retaining wall contractor, and the surveyor
who will be delineating this line.
In general, in order for trees to survive the stresses placed upon them in the construction
process, tree protection must be planned in advance of equipment arrival on site. If tree
protection is not planned integral with the design and layout of the project, the trees will
suffer needlessly and possibly die. With proper preparation, often costing little or
nothing extra to the project budget, trees can survive and thrive after construction. This
is critical for tree survival because damage prevention is the single most effective
treatment for trees on construction sites. Once trees are damaged, the treatment options
available are limited.
The minimum Tree Protection Measures in Attachment 4, Tree Protection Measures are
on separate sheets that can be copied and introduced into all relevant documents such as
site plans, permit applications and conditions of approval, and bid documents, so that
everyone involved is aware of the requirements. These Tree Protection Measures are
intended to be generic in nature. They will need to be adjusted to the specific
circumstances of the site that takes into account the location of improvements and the
locations of the trees.
Managed Forest Buffer Management Plan for the Greenline Building “B” Site
Weyerhaeuser Way South, Federal Way, WA 98003
Gilles Consulting
June 26, 2018
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General Maintenance Plan
Once the project is complete and the Landscape Plan is executed, a landscape
maintenance contractor shall be engaged to perform maintenance on the property; this
includes the maintenance of the MFB. The maintenance of the Buffer will be done in
accordance to the General Maintenance Plan noted in Attachment 5, below.
As noted below, there shall be an annual meeting of the property
manager/supervisor/owner’s representative, the in-house or contracted landscape
maintenance crew leader, and the Forest Manager. Together they will review the work of
the past year and discuss the work planned for the next year. The Forest Manager shall
review the work in relation to the goals of this management plan. Specific maintenance
requirements and replacement planting schedules are located below in Attachment 5,
Maintenance Schedule below and measures shall be enacted to ensure that the goals of
this plan are being met.
The Forest Manager shall provide the City of Federal Way with an annual report
documenting the current condition of the Forest Buffer and the quality of the work
performed in the past year. The report shall be forwarded to the City on or before the 30th
of December each year.
CONCLUSIONS AND RECOMMENDATIONS
The MFB is an asset to the property and the community. The MFB is in overall very
good condition and can continue to provide benefits in this fast growing city for decades
to come with the adherence to this Plan. Listed below, is a pallet of plant materials
recommended for replanting of the MFB and the right-of-way area between the eastern
edge of the Buffer and the edge of the road or sidewalk.
Managed Forest Buffer Management Plan for the Greenline Building “B” Site
Weyerhaeuser Way South, Federal Way, WA 98003
Gilles Consulting
June 26, 2018
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Recommended Plant Pallet
Large Native Trees:
Big Leaf Maple, Acer macrophyllum
Bitter Cherry, Prunus emarginata
Douglas Fir, Pseudotsuga menziesii
Mountain Ash, Sorbus americana
Pacific Madrone, Arbutus menziesii
Western Hemlock, Tsuga heterophylla
Western Red Cedar, Thuja plicata
Pacific Dogwood, Cornus nuttallii
Pacific Willow, Salix lucida, ssp. Lasiandra
Small Native Trees/Tall Native Shrubs
Black Hawthorn, Crataegus douglasii
Cascara, Rhamnus purshiana
Indian Plum, Oemleria cerasiformis
Service Berry, Amelanchier alnifolia
Vine Maple, Acer circinatum
Western Hazelnut, Corylus cornuta
Native Shrubs and Native Ground Cover Plants
Salal, Gaultheria shallon
Evergreen Huckleberry, Vaccinium ovatum
Ocean Spray (Creambush), Holodiscus discolor
Oregon Grape, Mahonia nervosa
Pacific Ninebark, Physocarpus capitatus
Pacific Rhododendron, R. macrophyllum
Red Elderberry, Sambucus racemosa, ssp. pubens
Red Huckleberry, Vaccinium parvifolium
Red-Flowering Currant, Ribes sanguineum
Red-Osier Dogwood, Cornus sericea
Snow Berry, Symphoricarpos albus
Sword Fern, Polystichum munitum
Wild Rose or Nootka Rose, Rosa nutkana
WAIVER OF LIABILITY
There are many conditions affecting a tree’s health and stability, which may be present
and cannot be ascertained, such as, root rot, previous or unexposed construction damage,
internal cracks, stem rot and more which may be hidden. Changes in circumstances and
conditions can also cause a rapid deterioration of a tree’s health and stability. Adverse
weather conditions can dramatically affect the health and safety of a tree in a very short
amount of time. While I have used every reasonable means to examine these trees, this
evaluation represents my opinion of the tree health at this point in time. These findings
do not guarantee future safety nor are they predictions of future events.
The tree evaluation consists of an external visual inspection of an individual tree’s root
flare, trunk, and canopy from the ground only unless otherwise specified. The inspection
may also consist of taking trunk or root soundings for sound comparisons to aid the
evaluator in determining the possible extent of decay within a tree. Soundings are only
an aid to the evaluation process and do not replace the use of other more sophisticated
diagnostic tools for determining the extent of decay within a tree.
Managed Forest Buffer Management Plan for the Greenline Building “B” Site
Weyerhaeuser Way South, Federal Way, WA 98003
Gilles Consulting
June 26, 2018
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As conditions change, it is the responsibility of the property owners to schedule
additional site visits by the necessary professionals to ensure that the long-term success
of the project is ensured. It is the responsibility of the property owner to obtain all
required permits from city, county, state, or federal agencies. It is the responsibility of
the property owner to comply with all applicable laws, regulations, and permit
conditions. If there is a homeowners association, it is the responsibility of the property
owner to comply with all Codes, Covenants, and Restrictions (CC&R’s) that apply to tree
pruning and tree removal.
This tree evaluation is to be used to inform and guide the client in the management of
their trees. This in no way implies that the evaluator is responsible for performing
recommended actions or using other methods or tools to further determine the extent of
internal tree problems without written authorization from the client. Furthermore, the
evaluator in no way holds that the opinions and recommendations are the only actions
required to insure that the tree will not fail. A second opinion is recommended. The
client shall hold the evaluator harmless for any and all injuries or damages incurred if the
evaluator’s recommendations are not followed or for acts of nature beyond the
evaluator’s reasonable expectations, such as severe winds, excessive rains, heavy snow
loads, etc.
This report and all attachments, enclosures, and references, are confidential and are for
the use of the client concerned. They may not be reproduced, used in any way, or
disseminated in any form without the prior consent of the client concerned and Gilles
Consulting.
Thank you for calling Gilles Consulting for your arboricultural needs.
Sincerely,
Brian K. Gilles, Consulting Arborist
ISA Certified Arborist # PN-0260A
ASCA Registered Consulting Arborist # RCA-418
ISA TRAQ Qualified
ISA TRAQ Certified Instructor
Managed Forest Buffer Management Plan for the Greenline Building “B” Site
Weyerhaeuser Way South, Federal Way, WA 98003
Gilles Consulting
June 26, 2018
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ATTACHMENTS
ATTACHMENT 1 - EXHIBITS .................................................................................... 18
ATTACHMENT 2 - CREATION AND BENEFITS OF HABITAT TREES, NURSE
LOGS, AND BRUSH PILES ......................................................................................... 19
ATTACHMENT 3 - TREE RISK ASSESSMENT PROTOCOL .............................. 22
ATTACHMENT 4 - TREE PROTECTION MEASURES ......................................... 24
ATTACHMENT 5 - GENERAL MAINTENANCE PLAN ........................................ 28
ATTACHMENT 6 - BIBLIOGRAPHY........................................................................ 31
Managed Forest Buffer Management Plan for the Greenline Building “B” Site
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ATTACHMENT 1 - EXHIBITS
Managed Forest Buffer Management Plan for the Greenline Building “B” Site
Weyerhaeuser Way South, Federal Way, WA 98003
Gilles Consulting
June 26, 2018
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ATTACHMENT 2 - CREATION AND BENEFITS OF HABITAT TREES, NURSE
LOGS, AND BRUSH PILES
There are occasions where hazardous trees need not be completely removed. Shortening
is the preferred method in these types of areas rather than complete removal. Standing
dead trees, also known as “vertical structure” in forest ecology terms, provide important
wildlife habitat. Recent studies at the University of Washington have shown that the
third most significant reason for the decline of songbirds in the Puget Sound region is the
lack of standing dead trees. (The primary reason for the decline of desirable wildlife is
loss of habitat. The second reason is predation by dogs, cats, Grey Squirrels, and
Opossums.)
These studies reveal that as many as 54% of
desirable urban wildlife utilize standing dead
trees, nurse logs on the ground, or brush piles in
one or more important life cycle. For instance,
Black Capped Chickadees must excavate a new
cavity every spring in order to successfully mate
and produce a brood of offspring.
The opportunity exists in the MFB to remove the
dangerous portions of hazardous trees and leave
the snags-Habitat Trees, nurse logs, and brush
piles for the benefit of wildlife. Trunk sections
can be carefully placed on the ground as nurse
logs. The logs, if in contact with the ground, soak
up moisture and release it slowly throughout the
summer. This supports plants and animals in the
immediate area. Brush piles can be strategically
placed for birds and mammals to use as safe areas also have important wildlife benefits.
These two measures have the added benefit of reducing the cost because a tree service
does not need to do as much clean up or removal.
The tree service
selected can spend a
few extra minutes on
the top of each snag
to make the cut look
like it was snapped
off in the wind—
jagged and irregular.
This enhances the
aesthetic appeal of the
tree.
Managed Forest Buffer Management Plan for the Greenline Building “B” Site
Weyerhaeuser Way South, Federal Way, WA 98003
Gilles Consulting
June 26, 2018
Page 20 of 31
Brush Piles
Brush piles can be thought of as a way to provide shelter.
In general, the concept of shelter is important to urban wildlife. In his book, Landscaping
for Wildlife in the Pacific Northwest, Wildlife Biologist Russell Link writes, “Shelter,
(also called cover) is a place to raise young, hide from predators, and avoid the heat, cold,
and wind. Shelter also provides a place to feed, play, and rest safely. The quality of
shelter is particularly important for young animals in a nest. Unlike an animal that can
flee when a predator approaches, young birds or small mammals must rely entirely upon
the cover and the camouflage of the nest itself.”
Different birds and mammals will use different parts of the brush pile as Table 1 Wildlife
That Use an Average-size Brush Pile, from page 123 of Mr. Link’s book notes:
For instance, insects will be attracted to the inside of brush piles that will become food or
other animals. “The inside of the pile can also protect wildlife from sun, rain, and
predators. During strong winds, birds that would ordinarily use an evergreen tree for
evening shelter may instead use a brush pile located on the ground out of the wind. Far
into a pile, mammals and some birds find nesting cover in the tight network of strong
twigs. The outside, where the sticks protrude from the pile, provides places for birds to
perch and sign, preen, and catch insects. If the base of the pile contains large limbs or
logs, salamanders, snakes, and lizards may hibernate there. Ants, worms, beetles, and
other insects will life and feed in the rich soil beneath a pile.”
Birds That Will Use the
Inside of the Brush Pile:
Birds That Will Use the Outside of the
Brush Pile:
Mammals That Will
Use the Inside of
the Brush Pile:
Reptiles and
Amphibians
That Will Use
the Base of the
Brush Pile:
Bushtits Grouse Chipmunks Alligator Lizards
Chickadees Hummingbirds Cottontail Rabbits Salamanders
Dark-eyed Juncos Jays Fox Snakes
Flycatchers Pheasants Ground Squirrels Toads
Golden-crowned Sparrows Robins Mice Turtles
Grouse Song Sparrows Rabbits
Pheasants Towhees Shrews
Quail Warblers Skunks
Song Sparrows White-Crowned Sparrows Voles
Thrushes Woodpeckers Weasels
Towhees Woodrats
White-Crowned Sparrows
Wrens
TABLE 1. WILDLIFE THAT USE AN AVERAGE--SIZE BRUSH PILE
Managed Forest Buffer Management Plan for the Greenline Building “B” Site
Weyerhaeuser Way South, Federal Way, WA 98003
Gilles Consulting
June 26, 2018
Page 21 of 31
“When snow covers a brush pile, a complex array of snow free spaces and runways
provides important habitat for protection and foraging by small mammals.” From pages
122 & 123, Landscaping for Wildlife in the Pacific Northwest by Russell Link.
Brush piles can be simple hand thrown piles of bio-debris and rocks or they can be large
designed piles.
Photo A: Brush piles
can be simple piles of
cut branches or raked
leaves.
Drawing A:
Brush piles
can be
complex
things that are
planned and
constructed.
Managed Forest Buffer Management Plan for the Greenline Building “B” Site
Weyerhaeuser Way South, Federal Way, WA 98003
Gilles Consulting
June 26, 2018
Page 22 of 31
ATTACHMENT 3 - TREE RISK ASSESSMENT PROTOCOL
To evaluate the trees for risk, as well as to prepare this report, I drew upon my 30+ years
of experience in the field of arboriculture and my formal education in natural resources
management, dendrology, forest ecology, plant identification, and plant physiology. I
followed the protocol of the International Society of Arboriculture (ISA) for tree risk
assessment. Published in 2011, the Best Management Practices, Tree Risk Assessment,
ANSNI A300 Part 9 was developed to aid in the interpretation of professional standards
and guide work practices based upon current science and technology. Using this process,
now called the Tree Risk Assessment Qualification, or TRAQ for short. This is a
scientifically-based process ensuring an examination of the entire site, surrounding land
and soil, as well as a complete look at the tree itself.
In examining each tree, I looked at such factors as: size, vigor, canopy and foliage
condition, density of needles, injury, insect activity, root damage and root collar health,
crown health, evidence of disease-causing bacteria, fungi or virus, dead wood and
hanging limbs.
Additional Testing
In the future, there may be trees that have signs and symptoms of decay or disease as well
as indications of good health and structure. These specific trees may require some
additional testing to fully determine a risk level. These tests could include a form of
structural analysis to determine the amount of sound wood and decayed wood in the trunk
or it could include analysis at a pathology lab to determine what pathogens are present
and at what levels. Wood analysis could be as simple as a long drill bit on a cordless
drill, a core sample, or a resistance test.
Failure
While no one can predict with absolute certainty which trees will or will not fail, we can,
by using this scientific process, assess which trees are most likely to fail and take
appropriate action to minimize injury and damage.
Levels of Assessment
The new protocol has three levels of assessment:
Level 1, Limited Visual Assessment:
o This is a visual assessment from a specified perspective of an individual
tree or population of trees in order to identify obvious defects or specified
conditions. This can be a walk by or a drive by review.
o A limited visual assessment typically focuses on identifying tees with
imminent and/or probable likelihood of failure.
o Typically used for large populations of trees and often done on a routine
schedule or after severe storms.
Managed Forest Buffer Management Plan for the Greenline Building “B” Site
Weyerhaeuser Way South, Federal Way, WA 98003
Gilles Consulting
June 26, 2018
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o The assessor performs a visual assessment, looking for obvious defects
such as dead trees, large cavity openings, large dead or broken branches,
fungal fruiting structures, large cracks, and severe leans.
o Level I Risk Assessments are generally used to identify trees that need
immediate management or trees that have indications of decline or poor
structure that need a Level II assessment.
Level II, Basic Assessment:
o This is a detailed visual inspection of a tree and its surrounding site and a
synthesis of the information collected.
o It requires that the assessor walk completely around the tree looking at the
site, buttress roots, trunk, and the entire canopy
o Level II may include the use of basic tools such as tape measures,
binoculars, magnifying glass, mallet, clinometer, trowel, shovel, probe,
and more.
o The Level II Basic Assessment includes conditions that ae detected from
the ground—internal, belowground, and upper crown factors may be
impossible to see or difficult to assess and may remain largely undetected.
Level III, Advanced Assessment:
o Advanced assessments are performed to provide detailed information
about specific tree parts, defects, targets, or site conditions.
o They are usually conducted in conjunction with or after a Level II Basic
Assessment if the tree risk assessor needs additional information and the
client approves the additional service.
o Specialized equipment, data collection and analysis, and/or specialized
expertise are usually required for advanced assessments. These
assessments are therefore generally more time intensive and more
expensive.
o Procedures and methodologies should be selected and applied as
proportionate, with consideration for what is reasonable and proportionate
to the specific conditions and situations the risk manager/property owner
should consider the value of the tree to the owner or the community, the
possible consequences of failure, and the time and expense to provide the
advanced assessment.
Managed Forest Buffer Management Plan for the Greenline Building “B” Site
Weyerhaeuser Way South, Federal Way, WA 98003
Gilles Consulting
June 26, 2018
Page 24 of 31
ATTACHMENT 4 - TREE PROTECTION MEASURES
In order for trees to survive the stresses placed upon them in the construction process,
tree protection must be planned in advance of equipment arrival on site. If tree protection
is not planned integral with the design and layout of the project, the trees will suffer
needlessly and will possibly die. With proper preparation, often costing little, or nothing
extra to the project budget, trees can survive and thrive after construction. This is critical
for tree survival because damage prevention is the single most effective treatment for
trees on construction sites. Once trees are damaged, the treatment options available are
limited.
The following minimum Tree Protection Measures are included on separate sheets so that
they can be copied and introduced into all relevant documents such as site plans, permit
applications and conditions of approval, and bid documents so that everyone involved is
aware of the requirements. These Tree Protection Measures are intended to be generic in
nature. They will need to be adjusted to the specific circumstances of your site that takes
into account the location of improvements and the locations of the trees.
Note: The Tree Protection Measures outlined over the next several pages meet or exceed
those as spelled out in the 1994 FWCC 1568(c)(6)a-g. That is, the fences will be 6 foot
high, one foot higher than the code. There will be absolutely no construction activities,
including storage of materials, equipment, vehicles, supplies, or debris within the tree
protection zones behind the Tree Protection Fences. There will be no grade changes
within the Tree Protection Zones. Any encroachment into the MFB will be discussed by
the design team and a request will be made in advance to the Planning Department staff
explaining the situation, what needs to be accomplished, why encroachment is a logical
solution, and how the Significant Trees in the immediate vicinity will be protected. No
encroachment will occur without prior written permission of the Forest Manager and the
Planning Director or designee as required by 1994 FWCC 1568(c)(6)g.
Managed Forest Buffer Management Plan for the Greenline Building “B” Site
Weyerhaeuser Way South, Federal Way, WA 98003
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June 26, 2018
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TREE PROTECTION MEASURES
1. Tree Protection Fencing:
a. Tree Protection Fences will need to be placed around each tree or group of
trees to be retained.
i. Tree Protection Fences are to be placed according to the attached
drawing.
1. The area inside the fences is the Tree Protection Zone.
2. The area outside the fences is the work zone or the
construction zone.
ii. Tree Protection Fences must be inspected and approved by the
Forest Manager prior to the beginning of any demolition or
construction work activities.
iii. Nothing must be parked or stored within the Tree Protection
Fences—no equipment, vehicles, soil, debris, or construction
supplies of any sorts.
b. Signs:
i. The Tree Protection Fences need to be clearly marked with the
following or similar text in four inch or larger letters:
“TREE PROTECTION FENCE
DO NOT ENTER THIS AREA
DO NOT PARK OR STORE MATERIALS
WITHIN THE PROTECTION AREA
Any questions or concerns, call Brian K. Gilles at Gilles
Consulting
@ 425-417-0850”
2. Cement Trucks:
a. Cement trucks must not be allowed to deposit waste or wash out materials
from their trucks within the Tree Protection Fences.
3. Canopy Pruning:
a. The need to prune any tree canopies for construction clearance and worker
safety will be made by the Forest Manager in consultation with the general
contractor and the retaining wall contractor as well as the owner’s
representative.
b. Pruning will take into account the needs of equipment and the safety of the
workers and the use of the parking lot.
c. The pruning must be done by an International Society of Arboriculture,
(ISA) Certified Arborist using current industry standard pruning
techniques. (ANSI A300 Pruning Standards and ANSI Z131.1 Safety
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Weyerhaeuser Way South, Federal Way, WA 98003
Gilles Consulting
June 26, 2018
Page 26 of 31
Standards as well as all OSHA, WISHA, and local standards must be
followed.)
d. Plant debris can be chipped and utilized on site for the mulch under the
trees.
4. Excavation:
a. When excavation occurs near trees that are scheduled for retention, the
following procedure must be followed to protect the long term
survivability of the tree:
b. The Forest Manager, or qualified designee, must be working with all
equipment operators.
i. The Forest Manager should be outfitted with a shovel, hand
pruners, a pair of loppers, a handsaw, and a power saw (a
“sawsall” is recommended).
c. The Hoe:
i. The hoe used at first must be a small landscape sized hoe with a
thumb attachment.
ii. The hoe must be placed to gently comb back the duff layer and
upper layers of soil using the tines on the bucket.
iii. All soil, spoils, and debris is to be moved away from the Forest
Buffer. No storing or stockpiling of soil or any other materials is
allowed in the MFB.
d. Root Exposure and Pruning:
i. When any roots of two inches diameter or greater are exposed, of
the tree to be retained, the Forest Manager, or designee, shall hand
dig the root and properly prune the root using the most appropriate
sharp and clean tool from the list above.
ii. This excavation procedure shall continue until Forest Manager, or
designee, determines that the excavation is deep enough that no
more significant roots will likely be exposed.
e. The small hoe can then excavate down to its limits of depth.
f. The larger hoe can then take over the excavation to the proper depth and
of the rest of the site.
5. Putting Utilities Under the Root Zone:
a. Boring under the root systems of trees (and other vegetation) shall be done
under the supervision of the Forest Manager, or designee. This is to be
accomplished by excavating a limited trench or pit on each side of the
critical root zone of the tree and then hand digging or pushing the pipe
through the soil under the tree. The closest pit walls shall be a minimum
of 7 feet from the center of the tree and shall be sufficient depth to lay the
pipe at the grade as shown on the plan and profile.
b. Tunneling under the roots of trees shall be done under the supervision of
the Forest Manager in an open trench by carefully excavating and hand
Managed Forest Buffer Management Plan for the Greenline Building “B” Site
Weyerhaeuser Way South, Federal Way, WA 98003
Gilles Consulting
June 26, 2018
Page 27 of 31
digging around areas where large roots are exposed. No roots 1 inch in
diameter or larger shall be cut.
c. The contractor shall verify the vertical and horizontal location of existing
utilities to avoid conflicts and maintain minimum clearances; adjustment
shall be made to the grade of the new utility as required.
Managed Forest Buffer Management Plan for the Greenline Building “B” Site
Weyerhaeuser Way South, Federal Way, WA 98003
Gilles Consulting
June 26, 2018
Page 28 of 31
ATTACHMENT 5 - GENERAL MAINTENANCE PLAN
This General Maintenance Plan consists of two distinct parts: Part 1, Restoration and
Tree Protection during Construction. Part 2: on-going annual maintenance to maintain
the character of the MFB into the future.
A crew of three, or more, skilled and trained staff will be the minimum per maintenance
event. The crews must be outfitted with an insured vehicle that has all of the required
power and hand tools, all needed safety and personal protection equipment required for
each crew member, all needed supplies, and a means of off-site disposal of debris and
waste that is not recycled on site.
Part 1, Restoration and Tree Protection:
As noted in the tree protection measures above:
The Forest Manager shall be on site to inspect the location and proper installation
of the limits-of-disturbance/tree protection fences.
o The fence installation must be approved and documented by the Forest
Manager prior to the initiation of any clearing, grubbing, or construction
work.
o This shall be documented in a field report to the City.
As the forest is cleared for the development, the Forest Manager will be on site to
work with the contractors to minimize damage to the roots of trees in the buffer.
o This will be done by implementing the Tree Protection Measures, Section
5, Excavation, as noted immediately above.
As the forest is cleared for the development, the Forest Manager will still be on
site to review any damage done to trees along the edge of the MFB and determine
if any trees pose an unacceptable level of risk to property or the construction
crews or others utilizing the site.
o Any trees deemed an unacceptable level of risk will be documented and
removed as part of the clearing and grading process.
o These will be documented by the Forest Manager in a report to the City.
o Replacement Trees will be installed as part of the landscape plan in
accordance with replacement ratios required by the City.
Once the area of development and construction is cleared and graded, the
landscape plan will be implemented as desired by the property owner and
developer.
The landscape plan will be inspected by the Forest Manager as follows:
o Plant materials will be inspected as they are unloaded from the truck.
The landscape contractor will call one week in advance and set a
time and date for the trucks to arrive and the inspections to occur.
Plants will all conform to current American National Standards
Institute, (ANSI), for Grade A top quality plant materials.
o The Forest Manager will perform spot checks during installation to verify
that proper installation procedures are being followed.
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o The Forest Manager will perform a formal final inspection with the
general contractor, the landscape installation contractor, the Landscape
Architect, the Environmental Consultant, and the Forest Manager to insure
that the plans have been properly fulfilled.
Part 2, Annual Maintenance Years 1 – 3:
Year One Maintenance:
o A Maintenance Event shall consist of the following work activities:
Litter Control.
All litter from the MFB and right-of-way must be picked
up, removed from the site, and properly disposed of.
Plant Maintenance:
All newly installed plants are to be inspected, righted and
re-staked if needed.
Dead branches and tops are to be properly pruned using
current ANSI A300 Pruning Standards and sterilized sharp
implements.
Plant Replacement:
Dead trees and shrubs will be inventoried during the
September Annual Meeting of Staff, described below.
A discussion will be done to ascertain the cause of death of
the plants.
Actions will be taken to remediate any landscape problems
that lead to the plant death.
New plants will be ordered.
Re-placement plants will be installed in October or
November.
Invasive species are to be removed.
Given the low level of invasion currently, manual removal
is preferred.
However, if a rapid invasion occurs and an invasive species
appears to be out of control, proper use of herbicides
applied by a State of Washington Licensed Pest Control
Applicator may be used.
There will be one maintenance event as described above once per
month in Years 1, 2, and 3.
o Annual Meeting of Staff and Reporting:
Each September, the Forest Manager will meet with the
maintenance crew leader and the property manager/owner’s
representative to review the work of the previous year.
The meeting will take place while walking the MFB and a
copy of this maintenance plan will be the basis of the
review and the report following.
Managed Forest Buffer Management Plan for the Greenline Building “B” Site
Weyerhaeuser Way South, Federal Way, WA 98003
Gilles Consulting
June 26, 2018
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Year Two Maintenance:
o This will be the same as Year 1 with one addition:
o Tree stakes will be inspected on all newly installed trees.
If appropriate, tree staking/tethering will be removed. This will
apply to the majority of the trees. A few trees may need to be re-
staked and checked at a later date.
Year Three Maintenance:
o This will be the same as Year 1 with one addition:
o Tree stakes will be removed from the remaining installed trees.
Year Four Maintenance and Beyond:
o After year three, the level of maintenance can be reduced to one
maintenance event per quarter. The same maintenance activities and
requirements shall prevail into the future. These include:
Litter Control.
All litter from the MFB and right-of-way must be picked
up, removed from the site, and properly disposed of.
Plant Maintenance:
Dead branches and tops are to be properly pruned using
current ANSI A300 Pruning Standards and sterilized sharp
implements.
Invasive species are to be removed.
Given the low level of invasion currently, manual removal
is preferred.
However, if a rapid invasion occurs and an invasive species
appears to be out of control, proper use of herbicides
applied by a State of Washington Licensed Pest Control
Applicator may be used.
There will be one maintenance event as described above once per
quarter in future years.
o Annual Meeting of Staff and Reporting:
Each September, the Forest Manager will meet with the
maintenance crew leader and the property manager/owner’s
representative to review the work of the previous year.
The meeting will take place while walking the MFB and a
copy of this maintenance plan will be the basis of the
review and the report following.
Managed Forest Buffer Management Plan for the Greenline Building “B” Site
Weyerhaeuser Way South, Federal Way, WA 98003
Gilles Consulting
June 26, 2018
Page 31 of 31
ATTACHMENT 6 - BIBLIOGRAPHY
1. Dirr, Michael A. Manual of Woody Landscape Plants, Their Identification, Ornamental
Characteristics, Culture, Propagation, and Uses. Champaign: Stipes Publishing Company, 1990.
2. Dunster, Dr. Julian A., R.P.F., M.C.I.P. Documenting Evidence, Practical Guidance for Arborists,
First Choice Books, Victoria, BC, Canada. 2014.
3. Eric Allen, et al. Common Tree Diseases of British Columbia. Victoria: Canadian Forest Service,
1996.
4. Harris, Richard W, James Clark, and Nelda Matheny. Arboriculture, Integrated Management of
Landscape Trees, Shrubs, and Vines. 4th ed. Upper Saddle River: Prentice Hall, 2004.
5. Johnson, Warren T. and Lyon, Howard H. Insects That Feed on Trees and Shrubs. Ithaca: Comstock
Publishing Associates, 1991.
6. Link, Russell, Landscaping for Wildlife in the Pacific Northwest, The University of Washington Press,
Seattle, WA. 1999.
7. Matheny, Nelda P. and Clark, James R. Evaluation of Hazard Trees. 2nd ed. Savoy: The International
Society of Arboriculture Press, 1994.
8. Matheny, Nelda P. and Clark, James R. Trees & Development, A Technical Guide to Preservation of
Trees During Land Development. Savoy: The International Society of Arboriculture Press, 1998.
9. Mathews, Daniel. Cascade -- Olympic Natural History. Portland, Oregon: Raven Editions with the
Portland Audubon Society, 1992.
10. Mattheck, Claus and Breloer, Helge. The Body Language of Trees, A Handbook for Failure Analysis.
London: HMSO, 1994.
11. Pojar, Jim and MacKinnon, Andy. Plants of the Pacific Northwest Coast. Redmond, Washington:
Lone Pine Publishing, 1994.
12. Pacific Northwest Chapter-ISA. Tree Risk Assessment in Urban Areas and the Urban/Rural Interface.
Course Manual. Release 1.5. PNW-ISA: Silverton, Oregon, 2011.
13. Petrides, George A. and Wehr, Janet. A Field Guide to Eastern Trees, Eastern United States and
Canada including the Midwest. New York: Houghton Mifflin Co mpany, 1998.
14. Scharpf, Robert F. Diseases of Pacific Coast Conifers. Albany, California: USDA Forest Service,
Agriculture Handbook 521, rev. June 1993.
15. Sinclair, Wayne A., Lyon, Howard H., and Johnson, Warren T. Diseases of Trees and Shrubs. Ithaca,
New York: Cornell University Press, 1987.
16. Smiley, E. Thomas, Nelda Matheny, and Sharon Lilly, Tree Risk Assessment Best Management
Practices, ANSI A300 Part 9: Tree, Shrub, and Other Woody Plant Management —Standard Practices
(Tree Risk Assessment a. Tree Structure Assessment). The International Society of Arboriculture
Press. Champaign. IL. 2011.
17. Watson, Gary W., and Neely, Dan, eds. Trees & Building Sites. Savoy: The International Society of
Arboriculture Press, 1995.