The Mount Lyell copper mine had been in care and maintenance since 2014 (ABC News: David Hudspeth)
The faulty platform two miners were working on before they fell to their deaths had “a high risk of failure”, an engineer has told a coronial inquest.
Coroner Simon Cooper is examining the deaths of three miners at the Mount Lyell Copper Mine in Queenstown.
Craig Gleeson, 45, and Alistair Lucas, 25, fell to their deaths on December 9, 2013, when the wood platform they were working on collapsed.
Thirty-nine days after the pair died, 55-year-old Michael Welsh was crushed by a sudden inundation of mud.
The court has heard the work platform was a makeshift construction made from lengths of King Billy pine.
Mr Gleeson and Mr Lucas were not wearing harnesses because “they got in the way”, the inquest heard, and fell 22 metres onto rocks when the platform broke.
On day four of the inquest, which began in Queenstown earlier this week but has now moved to the capital, Hobart engineer Adam Richards, who prepared a report on the fatal platform for Worksafe Tasmania, spoke.
He told the inquest today the pine platform appeared doomed to fail.
“An engineer would not choose to use King Billy pine,” Mr Richards said.
“The orientation of the grain was such it would not be considered a structural timber in any event.”
Mr Richards said the platform failed along its grain and was “overstressed to the tune of about 30 per cent”.
He said with an estimated combined weight of 264.1 kilograms, the platform was bending and should have been considered within the “medium” load category, demanding extra design protocols.
“The capacity was exceeded … there was a high risk of failure,” Mr Richards said.
“Nothing was fixed. It was just planks sitting on planks. There was no redundancy in this structure at all.”
The inquest previously heard from a mine supervisor, the platform had been subject to a “wiggle test”.
Mr Richards told the court proper platforms would be designed to shift and redistribute weight in the event of it coming under strain, but the pine platform had no such capacity.
“The way it was put together … there was only one way for it to go,” he said.
No concerns raised over use of pine platform
Former senior mining engineer at Mount Lyell, now Worksafe Tasmania principal inspector, Andrew Tunstall told the inquest he had visited the mine more than 50 times to carry out inspections.
But he said no-one raised concerns about the temporary pine platform and he did not even know it existed until the 2014 investigation into its collapse.
“As mining engineers, we didn’t have a lot of mechanical experience,” he said when asked if he had previously inspected the mechanical linkage arm to the platform.
“No-one expressed concern … I wasn’t aware the temporary platform was being used until the investigation.”
The inquest also heard the cost of the a safe, replacement platform would have been less than $1,800.
The widow of Michael Walsh is expected to give evidence to the inquest this afternoon.
The mine has been in care and maintenance mode since the death of Mr Welsh, and 200 jobs were lost.
The inquest continues.