HomeMy WebLinkAboutAttachment A: Arborist Report prepared by Advanced Arboricultural Assessment, dated 11/7/2025 of 1 10
Arborist Report
Subject:
Assessment of Big Leaf Maple which recently experienced crown failure which struck a home.
Prepared for:
Doan Thao
trungdoangoc@gmail.com
Prepared by:
Advanced Arboricultural Assessment
Chris Berg
ISA Certified Arborist and Risk Assessor PN1839A
LIC-TSP-18818
chris@advancedarboriculturalassessment.com
Site:
16432 108th Ave SE
Renton, WA 98055
Parcel #008800700
Site visit time/date:
10:30am/11-7-2025
Attachments:
•Site map
•Tree photos
•TRAQ forms
Summary:
•Both subject trees were found to be at high risk of whole tree failure due to severe basal
heartwood decay.
•Removal is recommended in a timely manner.
Methodology:
•The subject trees were assessed using the ISA basic risk assessment method, for a 1 year
timeframe, using basic hand tools, considering typical PNW weather with occasional high
winds, heavy rains, snow and ice.
•The subject tree risk assessment is limited to the trees assessed and specific risks of interest
not any and all risks.
•The subject tree risk assessment considers only specified targets, and visible or reasonably
detectable tree conditions.
•The subject tree risk assessment represents the perceived condition at the time of the
assessment.
•Not all defects are detectable, and a substantial number of failures are not predictable.
•The timeframe for the subject assessment is not and should not be considered a “guarantee
period” for the risk assessment.
•Only those specified in the assignment were assessed, and assessments were performed
within the limitations specified.
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Table of Trees
#Common
Name
Latin Name DSH Landmark
Tree Yes/No
Condition Likelihood of
failure
Likelihood of
impact
Consequences of
impact
Risk Action
1 Big Leaf
Maple
Acer macrophyllum 54”Yes Recent failure/Decay at base/Nesting cavity in
crown/Brittle cinder fungus
Probable High Severe High Remove
2 Big Leaf
Maple
Acer macrophyllum 38”Yes Topped/Uncorrected lean/Chained to adjacent
tree/Basal cavity nesting hole >75%
Probable High Severe High Remove
Site Map
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Observations:
(See attached photos and TRAQ forms for additional observations)
•Tree #1-Noted as having experienced recent crown failure in which a 10” diameter by 30’
limb failed at a crotch with decay and included bark present. The aforementioned failure
struck the adjacent home to the N causing significant damage to the home. A cavity/nesting
hole was noted directly below the failure site indicating heartwood decay has spread
throughout the subject stem. Column of decay noted in crotch on trunk at base with brittle
cinder fungus noted in decay. Fungus additionally noted on stem which experienced failure at
a base. Included bark noted between stems at base with horizontal cracking noted into root
collar.
•Tree #2-Noted as chained to tree #1 with uncorrected lean towards neighbors home. Chain
noted as under significant tension. Crown noted as topped in the past with weak
attachments of new growth. Trunk noted as having active nesting cavity with >75% structural
loss noted when probed. Hollow tones noted when sounded.
Conclusions/Recommendations:
•It is my professional opinion that both subject trees are at high risk of failure and should be
removed in a timely manner.
•When considering history of failure, extent of decay throughout all parts and active nesting
cavities, likelihood of failure of all parts was determined to be probable.
•When considering target proximity and part size, likelihood of impact was determined to be
probable with potential for significant to severe consequences of impact.
•When considering species profile for re-sprouting from stumps, with future weak attachment,
stump grinding is recommended along with tree removal.
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Subject trees noted as sharing a common canopy
with #2 being significantly suppressed.
Failure site noted as having severe decay at crotch
with included bark.
Tree #1 experienced recent major crown failure
with impact to home.
Stems noted as chained together with 1/2” tow
style chain. Chain noted as under significant
tension indicating load.
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Adventitious root growth noted at failure site
indicating severe decay.
Nesting cavity noted beneath failure site indicating
heartwood decay throughout stem.
Brittle cinder fungus noted in column of decay in
tree #1.
Decay noted extending into base in tree #1.
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Cracking noted below decay between co dominate
stems on tree #1.
Brittle cinder fungus noted on trunk opposite of
column of decay on tree #1.
Major, active nesting cavity noted at base of tree
#2.
Cavity in tree #2 probed to 75% depth of trunk with
hollow tones noted when sounded with sounding
mallet.
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TRAQ Form Tree #1 (front)
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TRAQ Form Tree #1 (back)
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TRAQ Form Tree #2 (front)
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TRAQ Form Tree #2 (back)