Maintenance and risk management of large trees and palms

The purpose of this Safety Alert is to highlight the risk large trees and palms can pose to people and the requirement to implement a regular maintenance and inspection regime.

Background

Well-publicised Coroner’s findings into deaths from falling branches in 2008, 2013 and 2014 highlight the duty of businesses and community groups to establish an appropriate inspection and maintenance program for large trees and palms under their management or control.

Persons with management or control of a workplace must eliminate the risks to health and safety, so far as reasonably practicable, and if it is not reasonably practicable to eliminate the risks to health and safety, to minimise those risks.

Good pruning improves the health of a tree, and pruning should be in accordance with the Australian Standard¹. The regularity of such pruning depends on a lot of things but in Darwin, with the climate that we have, all trees and palms should be inspected regularly to determine if any remedial work is required to be carried out. Arborists recommend an inspection every six months.

The following factors and actions need to be considered to ensure hazards are identified and mitigated.

Contributing factors

According to local experts all large trees and palms must be regularly maintained and inspected to ensure that the dangers and any risks associated are reduced as much as is possible.

The following are particular risks associated with large trees and palms:

Canopies becomes very dense and therefore top heavy;
In large trees, poor pruning techniques known as ‘lion tailing’ results in end-weighted primary leaders and branches which increases the risk of a limb failure at any time, particularly in the wet season as trees increase weight due to water uptake.
In the Top End all trees and palms have a shallow root system - therefore in the wet season when the soil becomes loose and saturated; trees and palms can fall over due to no anchor points being in place for their roots;
Nuts from coconut palms, particularly after they ripen, can fall to the ground at any time;
Infestation by white ants (termites) can be particularly destructive in a very short timeframe.
Summer heatwaves during extended dry periods affect older eucalyptus trees which can drop limbs at any time. Sudden unexplained limb failure is not common in the Top End – more so in the south where there is a significant difference in summer/winter temperatures resulting wood contraction/expansion.

Action required

Ensure large trees and palms are inspected by a qualified arborist regularly.
If identified urgent remedial work cannot be undertaken immediately, ensure appropriate placement of temporary security fencing to restrict access.
Only use qualified arborists to carryout out remedial or other tree works.
Extra care is required where trees and palms are situated in positions where their roots might not receive adequate water and nutrient uptake. This is always more difficult in situations where root systems are constrained by paving, raised garden beds or other hard landscaping.
De-nut coconut palms to manage the risk of falling objects.

Further information

Legislation

Work Health and Safety (National Uniform Legislation) Act 2011 (Section 20)
Work Health and Safety (National Uniform Legislation) Regulations 2011 (Part 3.1 and Regulations 54-55)