BMP - Tree Risk Assessment - 20

While there are many types of advanced assessments that can be conducted (see page 22), a few are described in Appendix 5. Tree risk assessors
are cautioned, however, that all technologies involve some uncertainty. Each
technology has limitations; any evaluation of an individual tree or target will
not be an accurate measure, but a qualified estimation.
Standard safe work practices and procedures should be applied for all
levels of assessment.

Defining the Scope of Work
Prior to beginning a tree risk assessment, the scope of work should be defined.
The tree risk assessor and client must agree on the goals, limitations, and
budget of the tree risk assessment. Some clients may be very experienced and
will have already developed a sophisticated scope of work. Often, however,
the risk assessor plays a significant role in documenting the scope.
Any property boundaries that restrict access to the tree(s) should be identified. Local government or authority's requirements for inspection, reporting,
and permitting should be considered. If a written report is to be presented
to someone other than the person who contracts with the tree risk assessor,
that person or agency should be identified.
The scope of work should include specifications for the following:
Identifying the tree(s) or area to be assessed. This may be the
location of a tree (for example, " the large oak tree in the front
yard " ) or it may include selection criteria (for example, " all trees
on Main Street greater than 12 inches [30 cm] in diameter " ). When
assessing trees for a municipality or large property, it is important to have maps
with defined boundaries and clear directions for assessing boundary trees.
The level and details of the assessment. One or more of the three levels
of assessment should be specified, as well as details that are to be included
within each level. If a limited visual inspection is selected, how the inspection is to be conducted and what information is to be recorded should be
described. For example, " The inspection procedure is a 'walk-by' from the
sidewalk, looking for any obvious, aboveground defects. "
Details of conditions to be assessed may also be included in the scope of
work. For example, trees often have many small, dead branches present, but
the tree risk assessor is concerned only about larger branches that can result
in serious consequences if they fail. Specifications for assessment may state
that only branches greater than 2 inches (5 cm) in diameter should be noted.
Similarly, details can be specified for the minimum degree of lean, live crown
ratio, degree of taper, or other conditions of concern (see Appendix 3).
20

BMP - Tree Risk Assessment

Table of Contents for the Digital Edition of BMP - Tree Risk Assessment