Prescribed burns are planned to mitigate the severity of bushfires. (Supplied: ACT Government)
In the ACT and surrounds, the list of sites marked for prescribed burns is long and the window of opportunity is short.
While autumn is typically the best time to conduct these burns, temperatures, wind, fuel moisture, fuel loads and local ecological requirements make the job an enormous balancing act.
ACT Parks and Conservation fire manager Neil Cooper said he and his team spent much of the year preparing for prescribed burns.
ACT fire management teams are on standby for when conditions are most favourable for controlled burns. (Supplied: ACT Government)
“Part of that includes grading roads and monitoring sites so that we can conduct the burns safely but also in an ecologically sustainable way,” he said.
“We’ve got to be aware of things like when the orchids are growing and the gang gangs are nesting.”
For Mr Cooper, specific measurements of environmental conditions are crucial.
“We’re looking for a fuel moisture content of around 12 per cent and we’re looking at humidity, wind direction, daytime temperatures as well as overnight temperatures,” he said.
“We’re also monitoring what resources are available and what other burns are going on around the country.”
Mr Cooper said teams were ready to be deployed as soon as conditions were right.
A prescribed burn in the south of Namadgi National Park broke containment lines and burned about 200 hectares. (ACT Emergency Services)
Things can change suddenly
When fire jumped the containment lines of a prescribed burn at Potters Hill on the ACT-NSW border last Sunday, crews faced winds up to 100 kilometres per hour.
More than 20 ACT fire crews and 10 NSW Rural Fire Service crews were stationed in the Potters Hill area, supported by five bulldozers and six aircraft.
The fire was brought back under control on Monday after an additional 198 hectares were burnt out.
ACT and NSW RFS crews worked overnight to bring the fire at Namadgi National Park under control within 24 hours. (Supplied: ACT ESA)
The head of the ACT Emergency Services Agency defended the decision to conduct the burn, suggesting the change in weather was not forecast when the burn started on March 10.
“It’s unfortunate but important to remember that we’ve done a lot of other prescribed burns around the ACT over the last two weeks,” Commissioner Dominic Lane said.
“It’s very important that we get on with these prescribed burns at this time of year because it’s the only window we do get.
“It’s the risk we have when dealing with fire in this environment.”
Winds up to 100kph contributed to a prescribed burn east of Potters Hill getting out of control. (Supplied: ACT ESA)
With just one day’s notice in the change in weather conditions, Mr Cooper said it was impossible to put the controlled burn out.
“We have tactics to secure these fires as best we can,” he said.
“This burn at Potters Hill was only 700 hectares, but it’s just not possible to put that fire out at a day’s notice.”
Mr Cooper said 15 of the 30 prescribed burns for the region had already been completed this year.
“Recent rain has allowed us to do the burns we’ve done, but we’re now getting to a period were the effects of that rain has diminished,” he said.
“We’ll now slow down our burning significantly until we get another rainfall event of 10 to 15 millimetres and then we’ll start again.
“The burns that we’re doing now are allocated to be done over a two-year window.
“One year you might not have the right conditions to get any of those burns done.”