HomeMy WebLinkAboutSS02 - Hazardous Trees in Urban ForestCity Council Agenda
Item No. SS #2
September 27, 1999
TO: Mayor and City Council
FROM: General Services Director
SUBJECT: Review of City's Methodology in Determining Hazardous Trees in
the City's Urban Forest
Recommendation:
None, informational report only.
Background:
On June 14, 1999, the Council authorized the emergency removal of 20 large trees
that were assessed by staff as potentially hazardous, which consisted of 6 trees
located on Marine Avenue and 14 trees on 4q' Avenue. After re- evaluation by staff
a total of 13 trees were removed, 7 from Marine Avenue and 6 from 4' Avenue.
The basis for the removals was the overall health of the trees, the proximity of
private property, an independent arborist report, and elevated readings from a tree
testing tool known as the Resistograph. Staff is prepared to discuss the validity of
the removal criteria. During the process of removing the trees, several public
comments were received relative to the validation of the health of the trees.
Discussion:
Staff routinely receives 30 -40 tree removal requests per month. The requests
typically received from the community are for tree removals due to view
obstruction, alleged property damage, litter and debris nuisance, or other reported
hazards. In evaluating these requests, staff's primary concern is assessing
potential hazards. Arborists define that a hazardous tree situation requires the
presence of both a defective tree and a target (buildings, structures, etc.) Staff
evaluates each individual tree situation, assesses the hazard potential, prepares a
written report (when time permits) and recommends appropriate action. In the
case of imminent danger to personnel or property, such as occurred on 4`s Avenue
during an El Nino storm with a severely leaning tree, staff proceeds with the
removal.
Staff has prepared a visual display and a handout explaining the evaluation of
hazardous trees and some examples in the City. In addition, a tool called the •
Resistograph, used to assist in determining hazard potential, will be demonstrated
and discussed by staff and various experts. The Resistograph is a computerized
bore tester used as an auxiliary diagnostic tool.
The following presentation will facilitate an understanding of the evaluation of
hazardous trees as well as the process that staff uses to determine when removal is
necessary:
Tree Presentation
t. Introductory Remarks — General Services Director
2. Evaluation of Hazardous trees — Urban Forester
3. Private Industry Uses of the Resistograph — Michael Mahoney, Urban Forestry
Consultant and Scott Baker, Resistograph
4. Tree Topping — 701 Iris — Urban Forester
5. Council — Questions/Comments .
6. Public Input
In conclusion, staff will continue to consider all factors when confronted with
hazardous tree situations. The use of the resistograph will be confined to an
auxiliary role in any removal decision.
Very respectfully,
David E. Niederhaus
DEN/kr
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