By Ted McIntyre with Laura Watson, 7 Oaks Tree Care & Urban Forestry Consultants
Why You Should Consult An Arborist Pre-Construction
Most municipalities require some form of arboricultural planning and consulting for trees, whether the site is a densely treed ravine lot, an urban interior lot, or somewhere in between. But why else should trees be preserved on a building site? The reasons vary from municipal requirements to environmental benefits to the sheer monetary value of those trees.
Acknowledging the trees at the beginning of your development can eliminate the requirement for potential revisions to plans due to conflicts with trees, making the preservation process easier and more cost-effective. But you’ll need an expert in this department. Retaining an experienced consulting arborist from the onset will allow you to identify potential disputes pertaining to your development footprint, heritage trees, or potential legal issues. An experienced consulting arborist can highlight municipal constraints placed on trees (i.e. minimum tree protection zones) or provincial constraints (such as the Endangered Species Act), identify conflicts with neighbouring or boundary trees, confirm whether trees are suitable for preservation or in declining condition, and determine whether they’ll be able to survive the anticipated construction impact.
And you need to involve these specialists throughout the process, including planning, design, pre-construction, construction and post-construction. Laura Watson, the principal and consulting arborist at 7 Oaks Tree Care & Urban Forestry Consultants Inc., helps us get to the root of the matter.
OHB: What sort of questions can a consulting arborist answer?
LW: “There are many! They’ll begin with a review of the pertinent municipal policies: Do you actually need tree permits? What size trees are protected under the local by-laws? What size trees must be included in a tree inventory based on the municipal policy? Are monetary valuations of trees necessary? Are permits required under Panning Act applications (i.e. site plan approval/plan of subdivision), or are tree injuries and removals governed by the final development conditions? Is the site located within an area regulated by the local conservation authority?
“A tree inventory is the next step. Knowing precisely what is on your site will provide insights into existing constraints due to provincial or municipal policies and by-laws, as well as any potential legal issues (i.e. endangered species, boundary trees or nearby trees on neighbouring properties). Your arborist should affix a physical tag onto the inventoried trees for easy identification in the field. All inventoried trees should be located on your site survey to accurately represent their placement, especially regarding boundary or neighbouring tree issues. This inventory will allow your arborist to evaluate a tree’s suitability for preservation based on its species (including any provincial protection), condition, proximity to development (i.e. minimum tree protection zones or TPZs) and location based on as-of-right development envelope, etc. A tree inventory plan will also allow the arborist to convey tree locations and the potential for preservation and constraints to your design team during the planning phase.”
What happens at the design phase?
“Building on the tree inventory plan, the team can proceed with a preliminary design concept based on the developer’s wishes. Evaluation of these plans by the consulting arborist will provide greater insight into potential conflicts that may not be apparent. These can include:
1. Site Access – Can you get machinery into the site when TPZs are necessary? Can you install scaffolding? Can you store materials or fill on-site, or will it require removal?
2. Buildings/Hardscape – Will a tree be too close to a required building or pool excavation? Can building footprints be adjusted to accommodate both the building and the tree to satisfy municipal expectations or solve boundary tree issues?
3. Site Servicing – Where will new water and sewers be installed? Is there a natural gas hook-up? Is hydro above or below ground? Will that new pool and cabana require trenching for services?
4. Grade Changes – Are you cutting or filling near a tree? Are you installing a retaining wall? Where are your swales, French drains and other drainage infrastructure located? How will soil hydrology be altered?
5. Landscape – Is a pool being installed? A garden or address wall? A cabana, shed or pergola?
“An experienced consulting arborist can identify these conflicts before plans are finalized, eliminating costly back-and-forth with the design team.”
And the pre-construction phrase?
“Your consulting arborist can assist your team before construction commences in three ways. First, they can lay out the required TPZ fencing locations to eliminate installation mistakes and ensure municipal specifications are adhered to, thereby reducing approval times. Horizontal root zone protection can also be marked and checked.
“Second, they can communicate the importance of the TPZs to contractors. Tree health and survivability and often tree security deposits depend on adhering to the Tree Protection Plan. Ensuring all team members are aware is critical.
“And third, they can ensure qualified contractors complete all pre-construction specifications. This includes root excavations and root pruning, crown pruning or tying back for construction clearance, pre-construction fertilization or irrigation, and ensuring that surface treatments such as mulching are completed.”
How about during construction?
“Your arborist can visit the site periodically to ensure the approved Tree Protection Plan is adhered to. In the event of missteps, they can evaluate impacts on trees, document mitigation efforts and prescribe additional maintenance to aid tree survival.”
What is their role post-construction?
“Once all construction, including landscape, is completed, your consulting arborist can recommend removing TPZ fencing, root zone protection and other protection measures. Monitoring impacted trees can continue to identify issues that may manifest slowly after construction, especially after root cutting or soil compaction. Prescriptions for additional mitigation can be provided at this time.”
How much does it matter at what point you contract an arborist?
“They should seriously be one of the first calls you make when planning to develop. But make sure they’re familiar with local policies and by-laws and have a handle on construction constraints and requirements and basic planning policy. Involving them as early as due diligence with a quick pre-purchase site review can save valuable time. It can eliminate any surprise constraints due to trees, speed up the planning and design phases, and set up your submission for quick approval.”
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