- Hub staff
We are always willing to follow up on questions raised by our readers. In this case, a resident was concerned about the impact of on-going excavations for fibre optic cable on behalf of Bell. "Why is this an acceptable practice from Bell, Pickards, and the City of Owen Sound? Trees that have been here longer than any of us to get damaged by a small conduit that likely could go somewhere else."
Residents can, of course, call City Hall and staff will provide answers to their questions. Often when a reader writes to us, it is because they are hoping we will share the information with their neighbours.
We sent our photographs and the resident's questions to a consulting arborist, senior City staff and Pickards Construction. We received responses from Certified Arborist Jared Tomlinson, and the Acting City Manager, Phil Eagleson.
Mr. Tomlinson did not make a site visit; he is providing professional information about tree health and stability.
"It is not good arboricultural practice to sever large structural roots within what is called a tree's structurally significant zone/structural root-plate—i.e., three times the diameter of the trunk, measured from its outer edge. Quite apart from the affect this can have on a tree's health (severing a singly major structural root within this area can result in the loss of 15% to 25% of a tree's root-system), severing large structural roots in within this area can compromise the tree's stability, making it more susceptible to up-rooting via wind-throw. This 3x threshold is well attested to in the literature—see, for example, the ISA's Tree Risk Assessment Manual, 2nd ed., (p. 61) or Dr. Tom Smiley's 2008 study Root Pruning and Stability of Young Willow Oak which established that severing structural roots at or outside of that 3x threshold has a statistically insignificant effect on tree stability. I have to acknowledge that a 5x threshold is considered an even better rule-of-thumb.". - Jared Tomlinson, Certified Arborist, ISA Certified Arborist ® ON-2473AISA Tree Risk Assessment Qualified
We appreciate Fire Chiel Phil Eagleson, Acting City Manager, sending this detailed reply to our enquiry:
"City Manager Tim Simmonds is away from City Hall this week on a well-deserved holiday.
In his absence I am writing in response to your inquiry.
Over the years we have had instances where trees have been severely impacted by construction similar to this, especially during sidewalk installation or replacement where at least one third of the roots have to be cut. We all know this action is not good for the health of the tree.
The constructor uses techniques to excavate around the tree to minimize the damage so there are no catastrophic or severe long-term impacts. To say it’s easy to relocate the structure is suggesting we didn’t consider alternative locations which is wrong. This location is unique. The original location for the conduit was proposed to be along the south side of 4th St E. However, the building/residence on the corner encroaches on the ROW and it is impossible to install any structures on that side of the road. Therefore, the conduit needed to be placed on the north side of the street. This location was not ideal as all the homes to be serviced are on the other side, resulting in another road crossing in the middle of the block.
In this case the conduit is run perpendicular from an existing Bell Pedestal on the east side of 2nd Avenue East to the suspected subject tree on the west side of 2nd Avenue East to provide utility service on the west side of 2nd Avenue East.
Unfortunately, the utility company has had to remove a portion of the trees’ root mass to install their upgraded utility. It appears that the utility company has tried to limit their impact on the tree as they have limited their excavation as much as possible by using hydro-vaccing and hand digging techniques.
We will monitor the tree over the next 2 years. If the tree dies within that time Pickard Construction will be responsible for replacement under the terms of maintenance in the contract. I cannot offer any comment on the length of or the likelihood of the survival of the tree(s) in question. We have spoken with the contractor and staff will continue to monitor the health of all trees impacted by the project."
Phil Eagleson, Acting City Manager