City strengthening tree protection guidelines during redevelopment

A lot of development is occurring downtown, and will continue for many years. There are over 20 sites that are in various stages of redevelopment, from known land assembly to an active application (see map). Through all this, residents have made clear they value trees in our downtown, so the challenge becomes protecting or replanting trees during redevelopment.When considering trees for preservation in very close proximity to large scale construction projects, staff consider the following:

1. Current condition of the tree: Is the tree healthy and structurally sound?  Both the city arborist and the developer's arborist are required to assess the health of the tree.

2. Is there currently adequate space for the tree to grow (to a species appropriate lifespan) above and below ground?  In a number of places in downtown Burlington, trees are in a 1.2m x 1.2m tree pit, which provides only 1.73m of root volume.  Medium sized trees require at least 23m of root volume to thrive. The city is revising tree planting guidelines in urban environments using new minimum soil volume requirements (see #5 below).

3. Construction Impacts: How will the tree be impacted through construction?  Will the crown be damaged by construction vehicles or the building?  Will the roots be damaged by the removal and replacement of sidewalk and/or driveways?

4. Downtown Streetscape Guidelines: These guidelines are currently being revised by the city with a draft expected this fall, and cover such matters as trees, sidewalk treatments, street furniture and beautification. The guidelines will require developers to reinstate the streetscape to our new standard, including for trees.

1. Tree planting guidelines: The city is also revising its tree planting guidelines to require minimum soil volumes for all new city trees.  This minimum requirement is over 10 to 15 times the rooting space that is currently given to City trees in urban areas (i.e. sidewalks). This minimum soil volume requirement will help us to grow bigger, healthier trees that require less care and less frequent replacement, which is environmentally and fiscally responsible.

When determining how and whether tree can be protected during redevelopment, staff make a decision based on the above criteria.Removal of city trees requires city council approval, and either replacement of a tree damaged or deposits to the city's tree reserve fund to replace trees.My Take: We should avoid removing healthy trees during redevelopment whenever possible, and continue to replant any trees taken down.  The revision to our tree planting guidelines is welcome and will help ensure a long life for future street trees, many of which are struggling now due to inadequate soil volumes.