Ausgrid trims trees growing too close to power lines to help keep the public safe around the electricity network and reduce the risk of bush fires. Trees contacting power lines also cause up to one in four blackouts.
Under statewide industry safety standards, vegetation should be kept at least one meter clear of bare low-voltage wires, or half a meter from aerial bundled cable. Our contractors clear vegetation growing inside these safety zones plus an allowance for annual regrowth. They then trim the branch to the nearest collar point, in accordance with Australian Standards 4373 Pruning of Amenity Trees.
In response to community concerns about the visual impact of tree trimming, our vegetation management team has been working with a number of councils over the past year to trial different cutting methods and approaches to manage these safety risks.
We have also set up a community stakeholder working group with representatives from community groups and more than 20 councils from across our network area.
In March 2016, we initiated a trial with City of Sydney to reduce the amount trimmed for regrowth in some locations to half a metre. Our arborists and contractors are monitoring these trees to see how fast they grow back inside safety clearances.
At the request of the Inner West Council, and in response to concerns raised by the community, this trial was extended to parts of the Inner West from September 2016 for a 12-month period. This followed correspondence from and a meeting with Council in July 2016 and further discussions in September 2016.
We are also trialing different ways of trimming trees in some locations in Ku-ring-gai at the Council's request, and partnering with Sutherland Shire and Newcastle City Councils on tree removal and replacement programs.
Our tree trimming costs have not been cut. Over the past six years the cost of these vegetation maintenance contracts has risen by $13 million to about $43 million a year.
The industry standard outlines that the way we trim depends on the species of tree, its proximity to the network and the type of powerline. There are additional safety clearances required in bushfire danger zones which cover 75% of land within Ausgrid’s network area.
Ausgrid’s network covers parts of Sydney, the Central Coast and the Hunter, from Waterfall in the South, west to Auburn and north to Scone.
In many of these areas, tall fast-growing trees have been planted directly under powerlines. Our powerlines are generally about 6 metres high, and some street trees planted near the network can grow up to 25 metres high, such as the Queensland brushbox. Managing these safety risks and preserving the amenity of local streets is challenging, and we are continuing to work with our contractors, Councils and the community to balance these concerns.
Any claim that decisions about these tree trimming trials have been influenced by Mr Armstrong’s personal interests or were to provide a personal benefit to Armstrong or any Ausgrid employee is without base and is totally rejected.
Aerial bundled cable was installed along the street where Mr Armstrong’s home is located in April 2003, prior to his purchase in December 2004. The safety clearance required around low-voltage aerial bundled cable under state-wide industry safety standards is 0.5 metres. Vegetation management contractors trimmed trees along this street to meet this standard in January 2017 and December 2015.