Protecting trees during development
The retention of healthy established trees is critical in order for Hobsons Bay City Council to achieve the ambitious canopy cover targets that have been set out in Council’s Urban Forest Strategy 2020.
This includes successfully protecting trees during development. The Australian standard for the protection of trees on development sites (AS4970 2009) has been developed to guide construction works around trees.
The standard describes a Tree Protection Zone (TPZ) as a combination of the root and crown area requiring protection during a development. The TPZ is calculated by multiplying the trunk diameter at breast height (measured at 1.4m above grade) by 12. It is an area that must be isolated from all construction activities.
Arborist reporting stages during development
When staring out a development where trees exist on or adjacent to the site, it is important to engage the services of a suitably qualified arborist to assist with appropriate tree management. Successful long-term retention of trees in the vicinity of construction work requires input from an arborist at each stage of a development project. This flowchart outlines the recommended involvement of an arborist in a generic development project where trees are present.
Reporting Guidelines Flowchart by Council Arboriculture Victoria Inc. licensed under CC BY-ND.
Preliminary Tree Assessment & Arboricultural Report
Before any plans are drawn up, it is important to engage the services of a suitably qualified arborist (minimum AQF Level V or equivalent) to assess the trees within and adjacent to the site. Within this report, the arborist will assess the health and structural condition of each tree within the site. Any trees protected under the planning scheme and/or the local law will be identified. Tree Protection Zones (TPZs) in accordance with AS4970 2009 will also be assigned to each tree, which will prove useful to inform the design.
Arboricultural Impact Assessment
Once the designs are drawn, they should be provided to the arborist who will determine any impacts to the existing vegetation using AS4970 2009 and will be able to provide appropriate tree management techniques to successfully retain trees that are worthy of retention.
Tree Protection Management Plan
The Tree Protection Management Plan is a concise document that outlines all tree protection controls specific to the site that must be followed by all personnel within the site. The plan must be provided to all workers on the site, with a copy always available for review. Any failure to comply with the plan may constitute a breach to the planning permit and may incur penalties.