A HOT piece of metal would have to be between 300-350 degrees to start the Weerite-Pomborneit Black Saturday fire, a court has been told.
The class action over the fire on February 7, 2009, at the Warrnambool Supreme Court is now in its fourth week.
On Wednesday Justice Jack Forrest heard from Paul de Mar, an expert on behalf of the plaintiff Terrence Place.
Mr de Mar, a principal consultant in natural resources and bushfire management at consultancy company GHD, said there were two forms of fire ignition — a piloted ignition, where a flame is present, and an unpiloted ignition (ie, auto ignition or spontaneous combustion).
The court heard three weeks ago from dairy farmer Kerry Lynee Callow, of Macarthur, who testified she was driving along the Camperdown side of the Weerite overpass on Black Saturday when she saw a blue flare which lasted for two or three seconds.
After seeing the flare she slowed down to look at the power pole but could not see anything wrong with it, then a fire caught her eye on the right hand side of the road.
At the time the court also heard from dairy farmer Regina Beal, from Weerite, who said she saw a large bright metallic flash of light between Peter Hay’s old dairy and the start of the overpass.
On Wednesday when Mr de Mar was cross-examined by counsel representing Powercor, David Curtain, he was asked that when he formed his opinion he had relied on — among other things — the evidence of Mrs Beal and Ms Callow about what they saw.
“That was part of the evidence that I was asked to take into account,” he said.
“Accepting that there was an arcing event, what they saw is the critical issue, isn’t it, because they saw the arcing event and evidence of fire?” Mr Curtain asked and Mr de Mar agreed.
Mr de Mar later said his point was that from the time the fire catches, whether that’s from an ignition that occurred an hour before or 30 seconds before, that’s the time you see a fire.
“You can’t report something that you can’t see so a small smouldering event that you couldn’t possibly see can’t be reported,” he said.
Mr Curtain said it might have taken tens of minutes between the initiation of the fire and the fire taking off.
Mr de Mar said that you could have a hypothetical scenario that there was something other than the source of the wires providing a smouldering ignition.
“It would be unlikely when the conditions are as they are but in a hypothetical world you could have that scenario,” he said.
“I don’t believe it would play out in these conditions.”
Counsel representing Mr Place, Tim Tobin, asked if the ignition of a fire was not by a pilot ignition but by a piece of hot metal, what would the temperature of the metal have to be to ignite grass in the conditions of Black Saturday. “In the range of 300-350 degrees Celsius,” Mr de Mar said.
The case is continuing.