jensen hazard tree decision STF20160004.pdfCITY OF EDMONDS
121 5th Avenue North, Edmonds WA 98020
Phone: 425.771.0220 • Fax: 425.771.0221 • Web: www.edmondswa.gov
DEVELOPMENT SERVICES DEPARTMENT • PLANNING DIVISION
f/le. 189v
February 29, 2016
Craig C. Jensen
dreraigj@icloud.com
Subject: Hazard Tree Removal (STF20160004)
Dear Craig,
On February 24, 2016, the City of Edmonds received a request from you to remove a potentially
dangerous fir tree at your parcel addressed as 6803 1641" Place SW in Edmonds. This letter is in
response to that request.
The slope north of your house is considered to be a critical area pursuant to Edmonds Community
Development Code (ECDC) Chapters 23.40 and 23.80 where slopes from 15% to 40% are considered
potential erosion hazards and slopes in excess of 40% are potential landslide hazards. Generally, the
removal of trees or vegetation within a critical area or critical area buffer is not an allowed activity
unless it involves the removal of invasive species or hazard trees, pursuant to ECDC 23.40.220.C.7.
You submitted a cover letter, aerial photo, photos of the tree, and a tree risk assessment form. Based
on this information, the tree has been shown to be a potential hazard and thus a candidate for removal.
As a result, its removal is considered to be an allowed activity relative to the critical areas code
referenced above and no further critical area reports are required. You have indicated that the tree will
be cut to a wildlife snag 15-20 feet tall and all downed material will be removed from the slope to
maintain slope stability.
According to ECDC 23.40.220.C.7.b(iv), hazard trees that are removed from critical areas as an allowed
activity must be replaced at a ratio of two -to -one. Replacement trees must be native and indigenous
and a minimum of six feet in height for evergreen species, one inch in diameter at breast height for
deciduous species, and eight feet minimum height for vine maples and other multi -stemmed trees. You
have indicated that two (2) 6-foot dwarf western red cedars will be installed in the same area as the
snagged fir, which meets the replacement requirement.
If you have any questions, please contact me at michael.clugston@edmondswa.gov or 425-771-0220.
Sincerely
Mike Clugston, AICP
Associate Planner
STF20160004
CRAIG C. JENSEN 6803 164TH PL SW
6803 164 Place S. W.
Edmonds, WA 98026-4918
Mark Clugston, AICP
Associate Planner
City of Edmonds
Edmonds, WA 98020
Dear Mr. Clugston,
Here is my plan for removing my potentially dangerous fir.
• 1 plan to cut it to a wildlife snag of about 15-20 feet and remove the downed debris.
• The two trees I will be planting as replacements will be dwarf western red cedars (Thuja
plicata "excelsa" or "watnong"). The trees will be planted a closely as possible to the new
wildlife snag and within the red circle below.
A check for $225.00 for the review fee is enclosed.
Thank you for your help.
Sincerely,
Craig C. Jensen
C]
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Arbor vell
professional tree management
Memorandum
TO: Craig Jensen
JOB SITE: 6803 164t" Place SW, Edmonds
REGARDING: Tree Risk Assessment
FROM: Scott Selby, Board Certified Master Arborist #PN-1775B, ISA Qualified Tree
Risk Assessor
DATE: February 9, 2016
Mr. Jensen:
I performed a Limited Visual Assessment of the subject Douglas fir tree (Pseudotsuga
menziezii) and it appears to be in good health. I observed no evidence of infection by
decay pathogens or infestation by pests. There does not appear to have been any recent
disturbance to the root zone and the form and structure of the tree appear to be
consistent with what I normally observe in other specimens of the same species. Under
normal weather conditions, I don't believe this tree represents a significant risk to your
property.
However, the recent failure in November of a tree of the same size and characteristics
immediately adjacent to your tree leads me to believe there is cause for concern.
Your home is situated at the top of a draw, which appears to act as a funnel, channeling
wind flowing up Puget Sound through your property. I suspect this funneling up North
Meadowdale Road draw contributed to —or caused —the recent failure of the adjacent fir.
It is not unreasonable to conclude that this same concentration of wind during
particularly strong wind conditions could lead to the failure of your tree.
The Overall Risk Rating of a tree takes into consideration three primary factors: the
Likelihood of Failure (condition or defect); the Likelihood of Impact to a target; and the
Consequences (injury or damage) if a target was struck by the tree or a portion thereof
(what is the value of the target and occupancy or frequency of use?).
Because the tree appears to be sound, it is likely there are no defects present that might
contribute to the tree's failure under normal weather conditions. For this reason, I rated
the tree's Likelihood of Failure as Possible rather than Probable.
PO Box 1586 BOTHELL WA 98041 OFFICE: (888) 969-8733
CELL: (206) 849-4718
WWW.ARBORWELL.COM
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Arbor ell
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However, because of the close proximity of the tree to your home and to powerlines, I
rated the Likelihood of Impact as High. Lastly, I rated the Consequences of Failure as
Severe to reflect the fact that occupancy of a home (primary target in this case) is
generally considered to be "Constant" (unless the home is occupied part time) and
because power lines (secondary target) also constitute a Constant target since they are a
permanent fixture.
Using the ISA Basic Tree Risk Assessment model led me to assign an Overall Risk Rating of
Moderate.
However, what I believe the overall calculation of risk using this formula fails to capture is
the elevated level of risk as a result of the topography unique to your location —as
demonstrated by the failure of the recent fir. I believe the next higher rating —High —
might represent more accurately the actual level of risk given the conditions present at
your home.
Lastly, consideration must be given to the fact that an individual's risk tolerance is largely
dependent upon one's exposure. Your perspective is likely very different from someone
who doesn't live there. Having to live day to day with the risk, you must decide the level
of risk that is tolerable before action must be taken to mitigate that risk.
I hope this report helps guide your decisions with the tree. Please contact me if I can
answer any questions or assist further in any way.
Scott Selby
Account Manager
Arborwell*)
PO Box 1586 BOTHELL WA 98041 OFFICE: (888) 969-8733
CELL: (206) 849-4718
WWW.ARBORWELL.COM
view looking north over client's house
at subject fir tree in backyard 1/26/16
7
view looking west at adjacent broken fir ,
with client's fir in background 1/26/16
4i , ,
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broken fir
client's fir
L
view looking NW at adjacent broken fir
1 !�� with client's fir in to left 1/26/16
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showing proximity of adjacent broken fir
to client's fir 3 -
broken fir
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photo taken by client after
top fell from adjacent fir
on 11 /17/15 knocking
~.. , ,�� • a ' out power for 2 days and
blocking road
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Aitxpid L)ivin-ac4
Wind funneling up N.
Meadowdale Road
drainage to Jensen home
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Image shows failed cedar tree at entirely different
location; included here to provide visual of owner's
concern for what might happen if the subject tree failed
onto their home; tree has speared through roof
.. AV*'
second image of failed cedar tree showing how it
penetrated roof and speared through upper floor; this
tree was approximately the same size and distance from
house as the Jensen fir tree but was NOT located within the
.same type of wind funneling topography
1, A Basic Tree Risk Assessment Form
Client Craig Jensen Date 1/25/16 Time 1000
Address/Tree� ocation ace Edmonds Tr e no. Sheet of
Tree species Pseudo suga menziesii dbh Height 1 Crown spread dia.
Assessor(s) 9cott Selby, isa traq, cma pn Time frame15-0 Tools used Vta
Target Assessment
Target zone
Occupancy
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Target description
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houses, overhead electrical conductors
4
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fence, landscaping
4
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3
4
Site Factors
History of failures adjacent similarly -sized fir lost half of top 11/17/15 Topography T at&SlopeO 40 % Aspect west
Site changes None ❑ Grade change ❑ Site clearing❑ Changed soil hydrology❑ Root cuts❑ Describe
Soil conditions Limited volume ❑ Saturated ❑ Shallow Compacted ❑ Pavement over roots ❑ % Describe
Prevailing wind direction sw Common weather Strong winds E Ice ❑ Snow ❑ Heavy rain ❑ Describe
Tree Health and Species Profile
Vigor Low ❑ Normal 0 High ❑ Foliage None (seasonal) ❑ None (dead) ❑ Normal % Chlorotic % Necrotic %
Pests Abiotic
Species failure profile Branches® Trunk❑ Roots® Describe overextended Ii`m5—s,-root and buttrot
Load Factors
Wind exposure Protected ❑ Partial ❑ Full ❑ Wind funnelingf """' ""U" Relative crown size Small ❑ Medium ❑ Large❑.
Crowndensity Sparse❑ Normal❑ Dense❑ Interior branches Few❑ Normal® Dense❑ Vines/Mistletoe/Moss❑
Recent or planned change in load factors
Tree Defects and Conditions Affecting the Likelihood of Failure
— Crown and Branches —
Unbalanced crown ❑ LCR 90 %
Cracks ❑ Lightning damage ❑
Dead twigs/branches ❑ %overall Max. dia.
Codominant ❑ Included bark ❑
Broken/Hangers Number Max. dia.
Weak attachments ❑ Cavity/Nest hole % circ.
Over -extended branches ❑
Previous branch failures ® Similar branches present ❑
Pruning history
Crown cleaned ❑ Thinned ❑ Raised ❑
Dead/Missing bark ❑ Cankers/Galls/Burls ❑ Sapwood damage/decay ❑
Reduced ❑ Topped ❑ Lion -tailed ❑
Conks ❑ Heartwood decay ❑
Flush cuts ❑ Other
Response growth
Main concern(s) limbs falling on fence and landscaping; not
primary concern
Load on defect N/A ❑ Minor ❑ Moderate
0 Significant ❑
Likelihood of failure Improbable ❑ Possible ® Probable
❑ Imminent ❑
—Trunk —
— Roots and Root Collar —
Dead/Missing bark ❑ Abnormal bark texture/color ❑
Collar buried/Not visible ❑ Depth Stem girdling ❑
Codominant stems ❑ Included bark ❑ Cracks ❑
Dead ❑ Decay ❑ Conks/Mushrooms ❑
Sapwood damage/decay ❑ Cankers/Galls/Burls ❑ Sap ooze ❑
Ooze ❑ Cavity ❑ % circ.
Lightning damage ❑ Heartwood decay ❑ Conks/Mushrooms ❑
Cracks ❑ Cut/Damaged roots ❑ Distance from trunk
Cavity/Nest hole % circ. Depth Poor taper ❑
Root plate lifting ❑ Soil weakness ❑
Lean ° Corrected?
Response growth normal
Response growth
whole tree failure onto house from strong
not primary concern
Main concern(s)
Main concern(s)
winds
Load on defect N/A ❑ Minor ❑ Moderate ❑ Significant 0 Load on defect N/A ❑ Minor ❑ Moderate ❑ Significant
Likelihood of failure
Likelihood of failure
Improbable ❑ Possible 0 Probable ❑ Imminent ❑
Improbable ❑ Possible 0 Probable ❑ Imminent ❑
Page I of 2
Risk Categorization
Likelihood
-0
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-0
Consequences
Failure
Impact
Failure & Impact
(from Matrix 1)
c
N
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Risk
rating
s
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a
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Conditions
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of concern
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Matrix 2)
trunk
potential trunk
18
60
1
n
0*0
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0
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mod
1
failure brought on
by strong, funneled
0000
0000
00100
o1O10
winds
010100
00010
0
100
0100
fence,
branch failure
6
100
2
n
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low
2
ng dscapi
010100
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11
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3
00000000.0
00
000
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000
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0000
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00
000
000
4-
4
010100
0
00
00100
000
Matrix I. Likelihood matrix.
Likelihood
of Failure
Likelihood of Impacting Target
Very low
Low
Medium
High
Imminent
Unlikely
Somewhat likely
Likely
Very likely
Probable
Unlikely
Unlikely
Somewhat likely
Likely
Possible
Unlikely
Unlikely
Unlikely
Somewhat likely
Improbable
Unlikely
Unlikely
Unlikely
Unlikely
Matrix2. Risk rating matrix.
Likelihood of
Failure & Impact
Consequences of Failure
Negligible
Minor
Significant
Severe
Very likely
Low
Moderate
High
Extreme
Likely
Low
Moderate
High
High
Somewhat likely
Low
Low
Moderate
Moderate
Unlikely
Low
Low
Low
Low
Notes, explanations, descriptions
Mitigation options
Overall tree risk rating
Overall residual risk
Low ❑ Moderate ® High ❑ Extreme ❑
Low ❑ Moderate ❑ High ❑ Extreme ❑
North
Residual risk
Residual risk
Residual risk
Residual risk
Work priority 1 ❑ 2 ❑ 3 ❑
Recommended inspection interva
Data ® Final ❑ Preliminary Advanced assessment needed ®No ❑Yes-Type/Reason
Inspection limitations NNone ❑Visibility ❑Access ❑Vines ❑Root collar buried Describe
4❑
This datasheet was produced by the International Society of Arboriculture (ISA) and is intended for use by Tree Risk Assessment Qualified (TRAQ) arborists - 2013
Page 2 of 2