20-104569-AD-Arborist Report-01-00-1900-V1 1
ARBORIST REPORT
for
- Federal Way 320th Library -
King County Library System
Parcel: 0821049222
848 South 320th Street, Federal Way, WA 98003
Friday, September 4th, 2020
Tuesday, November 17th, 2020
(Site map on final page of report)
By Izzy Nosan | ISA Certified Arborist WE-11653A | izzy@aplustree.com
3490 Buskirk Ave., Pleasant Hill, CA 94523 | (206) 550-6679 | www.aplustree.com
2
Background
Information
A Plus Tree, Inc. was contacted by LandCare - Tacoma Branch, who manage
the Federal Way 320th Library landscaping, requesting a tree risk assessment
of several red alders (Alnus rubra) located within the northeast quadrant of
the property. The assessment was regarding the present conditions, tree
integrity, and future expectations of the red alder trees in this area. The trees in
the northeast quadrant were assessed with specific focus on the trees’
potential risk to the eastern neighboring property, Trinidad South
Condominiums. There has been a recent and continual site history of red alder
failures in this portion of the library’s property. The tree failures have several
times contacted the Trinidad South Condominiums property, nearly missing
residents in some instances.
The trees included on this report were viewed as being high risk, given nearby
targets and occupancy rates, and have been recommended for removal.
The recommended removals are all within close proximity to critical targets
such as condominiums, the entrance road to the community, and frequently
used recreational and pet areas.
Assignment (and
any limiting factors)
A Plus was requested to assess the trees at Federal Way 320th Library and
provide a report regarding recommendations for safety concerns and potential
impact to the eastern neighboring condominiums, and to distinguish which, if
any, trees posed a risk. Landcare - Tacoma - intends to reduce the risk of any
tree failures and/or structural damage on site by acquiring arborist services for
mitigation if any trees are deemed high risk.
This report discuses the assessment of each individual red alder within the
northeastern corner of the library.
The only limitations to assessment was an excessive amount of Himalayan
blackberries obstructing a visible assessment of the lower trunks and root
flares of select trees.
Report continues on following page
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Observations 1)1 15” DBH red alder (Alnus rubra)
•A Plus Tree ID# 1001144161
a.This tree is in very poor condition with dieback in the canopy
and previous trunk failure. This tree has a significant easterly
lean toward the Trinidad South Condominiums.The trunk has
visible signs of decay with fungal fruiting bodies present. The
condominiums are within 1.5 X the height of the tree and the
recreational/pet area is within the drip line of the tree.
b.If retained, the tree is expected to either suffer whole-tree
failure, and/or other individual tree part failures in a heavy
loading event or under normal circumstances. Large-diameter
branches are found within the canopy. If any of these tree parts
were to fail and contact the condominiums, or a recreation-
area user, mild to severe consequences would be expected.
c.This tree is being recommended for removal in order to
minimize residual risk.
2)1 16” DBH red alder (Alnus rubra)
•A Plus Tree ID# 1001144162
a.This tree is in very poor condition with dieback in the canopy,
significant trunk decay, and dead sloughing bark. This tree has
a significant easterly lean toward the Trinidad South
Condominiums.The condominiums are within 1.5 X the height
of the tree and the recreational/pet area is within the drip line
of the tree.
b.If retained, the tree is expected to either suffer whole-tree
failure, trunk failure, and/or other individual tree part failures in
a heavy loading event or under normal circumstances. Large-
diameter branches are found within the canopy. If any of these
tree parts were to fail and contact the condominiums, or a
recreation-area user, mild to severe consequences would be
expected.
c.This tree is being recommended for removal in order to
minimize residual risk.
3)1 14” DBH red alder (Alnus rubra)
•A Plus Tree ID# 1001144163
a.This tree is in very poor condition with significant dieback in
the canopy and signs of structural root decay. This tree has a
easterly lean toward the Trinidad South Condominiums and
entry road to the community. The condominiums are within 1.5
X the height of the tree and the recreational/pet area an entry
roadway to the community is within the drip line of the tree.
b.If retained, the tree is expected to either suffer whole-tree
failure and/or other individual tree part failures in a heavy
loading event or under normal circumstances. Large-diameter
branches are found within the canopy. If any of these tree parts
were to fail and contact the condominiums, vehicle in the road
or a recreation-area user, mild to severe consequences would
be expected.
c.This tree is being recommended for removal in order to
minimize residual risk.
Report continues on following page
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4)1 12” DBH red alder (Alnus rubra)
•A Plus Tree ID# 1001144164
a.This tree is in very poor condition with dieback in the canopy
and expected trunk/root decay. This tree has a northernly lean
toward the Trinidad South Condominiums entry road and
guest-parking area. The road is within the drip line of the tree
and the parking area is within 1 X the height of the tree.
b.If retained, the tree is expected to either suffer whole-tree
failure and/or other individual tree part failures in a heavy
loading event or under normal circumstances. Large-diameter
branches are found within the canopy. If any of these tree parts
were to fail and contact a motorist or parked car, mild to
significant consequences would be expected.
c.This tree is being recommended for removal in order to
minimize residual risk.
Report continues on following page
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Testing and
Analysis
No soil assessment or advanced testing procedures were conducted.
Discussion Upon inspection of the site, the 4 red alders in the northeast quadrant of the
Federal Way 320th Library discussed in this report were viewed as high risk
and likely to fail under normal conditions.
Given the associated targets, occupancy rates, and significant/severe
consequences upon failure, the trees presented on this report were ranked as
being high-risk and hazardous to the Trinidad South Condominiums
community. Given the advanced decay, decline, and high-risk of the trees, they
have exhausted their usefulness as landscape trees and have become
liabilities; expected to fail towards critical target areas with occasional to
constant occupancy. There is a site history of several similar-tree failures
contacting the Trinidad South Condominiums. Future failures are expected to
occur in a heavy-loading event, or under normal conditions, if these trees are
retained as-is. Given that the associated targets are either within the dripline of
the trees or within 1.5X the dripline, they are expected to cause future property
or personal damage if retained.
Report continues on following page.
Recommendations Following the site visit to Federal Way 320th Library , and the assessment of
the red alder trees within the northeast quadrant of the property, the following
is recommended:
•The 4 trees on this report should be removed to the ground.
Alternative mitigation options were considered, but removal was deemed the
preferred recommendation out of practicality and to minimize residual risk.
PHOTOS ON FOLLOWING PAGES
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Attachments:
Photo 1a:
ArborPlus inventory
data:
Tree ID:
1001144161
Red alder in very
poor condition.
Significant lean
toward condos.
Signs of trunk decay.
7
Photo 1b:
Red alder in very
poor condition.
Significant lean
toward condos.
Signs of trunk decay.
8
Photo 1c:
Red alder in very
poor condition.
Significant lean
toward condos.
Signs of trunk decay.
9
Photo 2a:
ArborPlus inventory
data:
Tree ID:
1001144162
Red alder in very
poor condition.
Significant lean
toward condos.
Significant trunk
decay.
10
Photo 2b:
Red alder in very
poor condition.
Significant lean
toward condos.
Significant trunk
decay.
11
Photo 2c:
Red alder in very
poor condition.
Significant lean
toward condos.
Significant trunk
decay.
12
Photo 3a:
ArborPlus inventory
data:
Tree ID:
1001144163
Red alder in very
poor condition.
Significant lean
toward road and
parking area.
Structural root
decay. Significant
dieback.
13
Photo 3b:
Red alder in very
poor condition.
Significant lean
toward road and
parking area.
Structural root
decay. Significant
dieback.
14
Photo 3c:
Red alder in very
poor condition.
Significant lean
toward road and
parking area.
Structural root
decay. Significant
dieback.
15
Photo 4a:
ArborPlus inventory
data:
Tree ID:
1001144164
Red alder in very
poor condition.
Significant lean
toward road and
parking area.
Structural root
decay. Significant
dieback.
16
Photo 4b:
Red alder in very
poor condition.
Significant lean
toward road and
parking area.
Structural root
decay. Significant
dieback.
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Site Map