HomeMy WebLinkAboutT_Aborist Report_Jackson Short plat 011024
Lonnson Arbor Care
2616 169th Street SE
Bothell, WA 98012
425-891-1741
lonnson@juno.com
January 10, 2024
Tsai Residence
2223 NE 23rd St.
Renton, WA 98056
Re: Tree Report for the address above, Lot B (Parcel #0345700180).
To Whom It May Concern,
The purpose of this report is to identify and locate significant trees and associated risks for the
development of the property mentioned above. The enclosed survey table documents the identification,
measurements, and condition of each significant tree. A site map of the tagged trees and City of Renton’s
Tree Retention Worksheet is included at the end of this report.
On March 24th, 2022, I provided a basic inspection of 15 significant trees within and adjacent to the parcel
mentioned above. The trees were measured (with diameter tape) and existing tags were used for
identification. The tag numbers correspond with the data in the following tree inventory table. Tree
trunks are measured 4 ½ feet from the ground which is known as the Diameter at Standard Height (DSH).
The number within the brackets is the total DSH for multiple trunks derived from the square root of the
total diameter of all trunks; DSH = √[(DSH1)2 + (DSH2)2 + (DSH3)2 +…]. Trees that are considered
significant under Renton Code 4-11-200 are those 6 inches in diameter or greater (8 inches diameter for
Alders and Cottonwoods).
The total root zone known as the Limit of Disturbance (LOD) is the radius around the trunk that should
not be disturbed during grading and construction to preserve the root zone. The LOD is determined by
the species branch length from trunk (dripline), or a radial distance around the tree that is 1.25 times in
feet for every 1 inch in trunk diameter (1.25’ : 1.0”). The larger of the two shall be used under Renton
Code 4-4-130.H.10. The Critical Root Zone (CRZ) will be discussed later in the tree protection plan.
All trees have some level of risk associated with tree defects, or hazards. Hazards are categorized into
four types of risk assessed for a five-year period: Improbable, possible, probable, and imminent.
Improbable risk means the tree is stable, void of defects, and unlikely to fail under normal, and may not in
extreme, weather conditions. Possible risk means that failure is unlikely to occur in normal weather
conditions but may be expected in extreme weather conditions. Probable risk means failure may be
expected under normal weather conditions. Trees with imminent risk are in the act of failing and should
be worked on as soon as possible.
The health of the trees is defined as good, fair, and poor. Fair health describes a tree as having vigor but
has defects such as disease, included bark, wood decay, weak structure, or root zone (i.e., impervious
surfaces, compacted soil, etc.) that are not feasible for mitigation. Poor health describes a tree that is
dead, severely diseased, injured, or a hazard to surrounding property with no chance of recovery.
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Tree Inventory Table:
Tag #
Species DSH LOD Health Condition
677* Leyland cypress
Chamaecyparis leylandii
12.5” 12.0’ Good Sturdy tree with no signs of decay, disease,
or structural defects. Improbable risk of
whole tree or large part failure.
676* Leyland cypress 9.0” 9.0’ Good Sturdy tree with no signs of decay, disease,
or structural defects. Improbable risk of
whole tree or large part failure.
675* Leyland cypress 7.8” 8.0’ Good Sturdy tree with no signs of decay, disease,
or structural defects. Improbable risk of
whole tree or large part failure.
674* Leyland cypress 11.7” 12.0’ Good Sturdy tree with no signs of decay, disease,
or structural defects. Improbable risk of
whole tree or large part failure.
673* Leyland cypress 8.5” 9.0’ Good Sturdy tree with no signs of decay, disease,
or structural defects. Improbable risk of
whole tree or large part failure.
672* Leyland cypress 12.8” 12.0’ Good Sturdy tree with no signs of decay, disease,
or structural defects. Improbable risk of
whole tree or large part failure.
671* Leyland cypress 11.8” 12.0’ Good Sturdy tree with no signs of decay, disease,
or structural defects. Improbable risk of
whole tree or large part failure.
670* Leyland cypress 10.9” 10.0’ Good Tree leans to the east with a corrected
canopy. No signs of decay or disease.
Improbable risk of whole tree or large part
failure.
669* Douglas fir
Psuedotsuga menziesii
16.3” 14.0’ Good Sturdy tree with no signs of decay, disease,
or structural defects. Improbable risk of
whole tree or large part failure.
668 Douglas fir 17.9” 16.0’ Good Sturdy tree with no signs of decay, disease,
or structural defects. Improbable risk of
whole tree or large part failure.
666 Douglas fir 19.0” 18.0’ Good Sturdy tree with no signs of decay, disease,
or structural defects. Improbable risk of
whole tree or large part failure.
665 Portugal laurel
Prunus lusitanica
8.0”
4.2”
[9.0”]
8.0’ Good Sturdy tree with no signs of decay, disease,
or structural defects. Improbable risk of
whole tree or large part failure.
664 Portugal laurel 7.5”
6.6”
4.5”
[11.0”]
10.0’ Good Sturdy tree with no signs of decay, disease,
or structural defects. Improbable risk of
whole tree or large part failure.
662 Douglas fir 14.6” 14.0’ Good Sturdy tree with no signs of decay, disease,
or structural defects. Improbable risk of
whole tree or large part failure.
661 Douglas fir 18.8” 18.0’ Good Sturdy tree with no signs of decay, disease,
or structural defects. Improbable risk of
whole tree or large part failure.
* Trees in the utility easement.
000 Adjacent trees with root zones overlapping onto property.
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General Requirements:
This property is zoned R-8, single family residence. It requires the retention of at least thirty
percent (30%) of the good significant trees within the buildable area (Code 4-4-130H.1.a.i.).
There are a total of 13 trees with good health. Retaining four (4) significant trees will provide a
30.8% tree retention plan [(4 / 13) x 100% = 30.8%].
Tree Retention/Removal:
Tag # Retain Remove DSH
677 • 12.5”
676 • 9.0”
675 •
674 •
673 •
672 •
671 •
670 •
669 •
668 •
666 •
665 • 9.0”
664 • 11.0”
Total = 4 9 41.5”
There are thirteen (13) trees that are entirely within the property. 30% of the thirteen viable trees
must be retained. Retaining four (4) viable tree is required [(13 trees x 0.30) = 3.9, or 4 trees].
The Lot requires a tree density of two (2) significant trees for every 5,000 square feet (SF), or the
combination of existing trees and new trees equivalent to 12 inches in diameter. This lot is
10,556 ft2 and therefore requires a tree density of four (4) significant trees [(10,556 ft2 / 5,000
ft2) x 2] = 4.2, or 4 significant trees). Retaining the four trees shown in the tree retention table
provides more than the required minimum of 24 inches in total trunk diameter. New tree
plantings will not be required.
Tree Protection Plan:
Protective fencing is required around the perimeters of the LOD for each retained or group of
trees during grading and construction. Chain-link fencing is recommended to preserve the trees
from soil disturbance due to machines, foot traffic, and materials. Grading and construction
should not be allowed within the LOD of retained trees, unless described in this report.
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The placement for tree protection fencing is shown on the site map (page 5). The protection
fencing may cut across part of the LOD of trees 664 and 676 to provide room for building. This
fencing plan results in less than 20% disturbance of the outer root zone area and protects the
inner (critical) root zone area. In addition, Laurel 664 has limited to no root development under
tree 666. The young cypress 676 will recover from the planned impacts to the outer dripline and
does not require its removal to satisfy code 4-4-130.10.a. Mulching is recommended in the trees’
protection areas to provide “equal or better” protection for impacted trees. A 4-inch layer of
arborist wood chips within the LOD is adequate mulching.
The radius of the Critical Root Zone (CRZ) depends on the dripline (branch length) and DSH of
the tree. The CRZ is the area around the tree where root growth can recover and still maintain
stability. Generally, the CRZ ranges from ½ - ¾ of the LOD radius. The threshold for outer root
zone disturbance is no more than 30% of the area, not including the CRZ area. In correlation,
the placement of the protection fence perpendicular to the CRZ radius, at half the LOD radius, is
no more than 20% disturbance of the outer root zone.
New Tree Recommendations:
New tree plantings are not required for this development with the current retention plan, however
new trees are always welcome. Native trees are most preferred. Some of the larger native
evergreen (conifer) trees include Douglas fir (Psuedotsuga menziesii), Red cedar (Thuja plicata),
Western hemlock (Tsuga heterphylla), Grand fir (Abies grandis), and Sitka spruce (Picea
sitchensis).
Ornamental native trees and northern region trees more suited for landscape design may include
Excelsior cedar (Thuja plicata ‘Excelsior’), Mountain hemlock (Tsuga mertensiana), Shore pine
(Pinus contorta), Alaskan weeping cedar (Chamaecyparis nootkatensis), and Yew (Taxus spp.)
for evergreen conifers. Deciduous trees include Serviceberry (Amelanchier alnifolia), Dogwood
(Cornus nutellii or Cornus ‘Eddie’s White Wonder’), White oak (Quercus garryana), and Vine
maple (Acer circinatum).
Please reply if you have questions.
Thank you,
Lonnie Olson, Owner
ISA Certified Arborist (PN-5427A) exp. 12/31/2026
Qualified Tree Risk Assessor (#697) exp. 7/23/2024
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Property Map: 2223 NE 23rd St, Renton.
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Assumptions & Limiting Conditions
1. Any legal description provided to the consultant is assumed to be correct. Any titles and
ownerships to any property are assumed to be good and marketable. No responsibility is
assumed for matters legal in character. All property is appraised or evaluated as though
free and clear, under responsible ownership and competent management.
2. All data has been verified insofar as possible; however, I can neither guarantee nor be
responsible for the accuracy of information provided by others.
3. I shall not be required to give testimony or attend court by reason of this report unl ess
subsequent contractual arrangements are made, including payment of an additional fee.
4. Loss or alteration of any part of this report invalidates the entire report.
5. Possession of this report or a copy thereof does not imply right of publication or use fo r
any purpose by any other than the person to whom it is addressed, without the prior
expressed written or verbal consent of the consultant.
6. Neither all nor 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 the
consultant particularly as to value conclusions, identity of the consultant, or any reference
to any professional society or institute or to any initialed designation conferred upon the
consultant as stated in my qualification.
7. This report and values expressed herein represent the opinion of the consultant, and the
consultant’s fee is in no way contingent upon the reporting of a specified value, a
stipulated result, the occurrence of a subsequent event, nor upon any finding to be
reported.
8. Sketches, diagrams, 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.
9. Unless expressed otherwise: (1) information contained in this report cover s 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 plants or property in question
may not arise in the future.
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Certification of Performance & Appraisal
I, Lonnie Olson, certify that all the statements of fact in this report are true, complete, and correct
to the best of my knowledge and belief, and that they are made in good faith.
❑ I have personally inspected the trees and the property referred to in this report and have
stated my findings accurately. The extent of the evaluation or appraisal is stated in the
attached report and the terms of assignment.
❑ The analysis, opinions, and conclusions stated herein are my own and are based on current
scientific procedures and facts.
❑ No one provided significant professional assistance to me, except as indicated within the
report.
❑ My compensation is not contingent upon the reporting of a predetermined conclusion that
favors the cause of the client or any other party nor upon the results of the assessment, the
attainment of stipulated results, or the occurrence of any subsequent events.
I further certify that I am a member in good standing with the International Society of
Arboriculture. I have been involved in the field of arboriculture in a full-time capacity for more
than 25 years.
Signed: ________________________________