20170370 Tree Assessment 08102017SUF
SOUND URBAN FORESTRY,LLC
Appraisals — Site Planning — Urban Landscape Design and Management
Environmental Education — Environmental Restoration — Risk Assessments
8/10/17
Jerome W. Morrissette & Associates
Scott Severs, Project Manager
1700 Cooper Point Road SW, #B -2
Olympia, WA 98502
RE: Yelm High School Bypass Road Tree Assessment
Mr. Severs:
Upon your request, I have conducted a risk assessment along the clearing limits of the proposed
Yelm High School access road. Based on your direction, I identified and marked any hazard
trees within 100' of the clearing limits on either side of the new road.
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Overall Vegetation Description
Based on the species of trees and spacing within the area, this stand was likely at one time in
commercial timber production. The dominant species is Douglas fir with diameters ranging 8-
24" and averaging 16 ".
Tree Risk Assessment
The tree risk assessment methodology used for this report was developed by the International
Society of Arboriculture in 2013. It replaces the original method adopted in 2011.
Tree risk assessment can be conducted at different levels of intensity, each employing varying
methods and providing the client with varied options of reporting and recommendations. The
level selected should be appropriate for the assignment.
The ANSI standard for risk assessment and ISA's Best Management Practices: Tree Risk
Assessment defines three levels of tree risk assessment:
• Level 1: Limited visual
• Level 2: Basic
• Level 3: Advanced
Level 1 assessment involves a visual assessment of an individual tree or populations of trees near
specified targets, conducted from a specified perspective in order to identify certain obvious
defects or specified conditions. A limited visual assessment typically focuses on identifying
trees with imminent and/ or probable likelihood of failure.
A Level 2 or basic assessment is the standard assessment performed by arborists in response to
most private client requests for tree risk assessments. It consists of a detailed visual inspection
of a tree and its surrounding site and a synthesis of the information collected. A basic
assessment requires walking completely around the tree — looking at the site, buttress roots, trunk
and branches. Looking at the tree from some distance away, as well as close up, to consider
crown shape and surroundings.
Level 3 is an advanced assessment and it is performed to provide detailed information about
specific tree parts, defects, targets, or site conditions. It may be in conjunction with or after a
basic assessment if additional information is needed and the client approves the additional
service. Specialized equipment, data collection and analysis, and /or expertise are usually
required for advanced assessments. These assessments are, therefore, generally more time
intensive and more expensive.
After determining the likelihood of failure and the likelihood of impacting a target, the combined
likelihood of a failure impacting a target can be categorized. Matrix 1 can be used as a guide in
relating these likelihood factors within a given time frame. The resulting terms (unlikely,
somewhat likely, likely, very likely) are defined by their use within the table and are used to
represent this combination of occurrences in Matrix 2.
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Matrix 1. Likelihood of Failure
Likelihood of Failure
Likelihood of Impacting Tar et
Very Low
Low
Medium
High
Imminent
Unlikely
Unlikely
Likely
Very likely
Probable
Unlikely
Unlikely
Somewhat likely
Likely
Possible
Unlikely
Unlikely
Unlikely
Somewhat likely
Improbable
Unlikely
Unlikely
Unlikely
Unlikely
Matrix 2. Risk Rating
Likelihood of Failure and Impact
Consequences of Failure
Ne li ible
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
Field Data
Based on the criteria outlined above, I have identified 47 trees recommended for removal. This
includes 39 Douglas fir and 8 Austrian pine. They are considered moderate to high risks
considering the proximity to the project. Many of the trees are dead or their structures are poor
and are considered unsuitable to remain within reach of the proposed road and sidewalks. They
have been marked on the trunk with bright orange paint and should be easy to locate.
Please contact me if you should have questions.
Professionally Submitted,
Kevin M. McFarland, Principal
ISA Certified Arborist PN -0373 & ISA Tree Risk Assessment Qualified
Sound Urban Forestry, LLC
1910 E. 4th Ave., PMB 97
Olympia, WA 98506
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References
Dunster, Dr, Julian et al. 2013. Tree Risk Assessment Manual. International Society of
Arboriculture. Champaign, IL.
Mattheck, C. & Brelor, H (1998). The body language of trees. A handbook for failure
Analysis. Research for Amenity Trees No. 4. The Stationary Office, London.
Smiley, E. Thomas, Nelda Matheny and Sharon Lilly. 2011. Best Management Practices Tree
Risk Assessment. International Society of Arboriculture. Champaign, IL
Tree Removal Location Map
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Area with
majority of
Douglas fir
removals
No
Recommended
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