Tunnelling problems are plaguing the $12 billion Snowy 2.0 hydropower project, with a boring machine previously bogged in soft ground now wedged in hard rock and struggling to move.
The tunnel boring machine named Florence had been making slow progress in recent weeks as it cut through hard rock at the Tantangara site, one of several drilling locations in Kosciuszko National Park.
The ABC understands that earlier this month, Florence was mistakenly turned too sharply from a straight line into a curve, causing part of the cutting head to become wedged. Further boring compounded the problem, with the machine making only incremental movements since.
Multiple sources have told the ABC the situation is more serious than has been publicly acknowledged by Snowy Hydro and could take weeks or even months before normal drilling resumes.
"Wedged the thing in good and proper" one source said, with another simply saying, "It's f****d."
In a statement to the ABC, a spokesperson said "the project ceased excavation by the TBM (tunnel boring machine) on Thursday, May 16 due to rock pinching on the machine's shield."
Rejecting the notion Snowy Hydro had not been up-front about the extent of the problems, the statement noted that "[the] update on TBM operations was provided within 24 hours of the machine being stopped."
"The Snowy 2.0 project team sought immediate advice from a specialist contractor with experience at other Australian projects with the same TBM situation.
"[On Monday] the contractor commenced work using high-pressure water jets to remove the rock impinging on TBM Florence's shield. Timing for estimated recommencement of excavation will be determined on the successful removal of the rock."
Snowy Hydro has flagged that it will provide further updates next week.
Earlier this month, Snowy 2.0 senior project manager Guy Boardman told the ABC he was confident Florence could pick up the pace during later stages of tunnelling.
"It will get a lot easier and pick up when we get out of this curve. They don't have very good turning circles, these tunnel boring machines."
Another chapter of woe in the Snowy 2.0 story
The Snowy 2.0 project involves building an underground hydropower station in the heart of Kosciuszko National Park, with tunnels linking Tantangara Dam high up in the mountains to Talbingo Reservoir lower down.
Once completed, it will be able to generate 2,200 megawatts of power when water flows from Tantangara to Talbingo, which can be used on demand to support the variable contributions of other renewable energy sources to the power grid.
Loading YouTube content
It was always going to be an ambitious undertaking. When first announced by the Malcolm Turnbull government in 2017, it had an estimated cost of $2 billion and was expected to deliver its first power in 2021.
A succession of cost blow-outs and time delays mean it is now slated to cost $12 billion and deliver its first power in late 2027.
There have been a series of safety issues including toxic gases filling the tunnels during construction, as exposed last year by the ABC's Four Corners program.
Earlier this month, there was a partial tunnel collapse as blasting in one area breached an adjacent tunnel.
But the persistent problems with Florence the tunnel boring machine have become emblematic of Snowy 2.0's issues.
It is meant to be boring the longest and most technically difficult section of the project, the "headrace" tunnel linking the upper Tantangara dam to the underground power station.
But Florence was stuck for most of 2023 when it became bogged in soft ground, opening up a sinkhole in the alpine plains above it. Even when it resumed boring earlier this year, it was struggling to progress through hard rock.
Snowy Hydro and its joint venture partner Future Generation have been considering whether to purchase a fourth tunnel boring machine for the project. If acquired, it would work on the "headrace" tunnel from the other end to speed up progress, but a final decision has not been made.
Energy Minister Chris Bowen has told the ABC he still expects the revised completion date of 2028 to be met, but expressed frustration at how the project was initially managed.
"It was undercosted at the beginning. There was not enough work done on the due diligence of the tunnelling, and the risks involved," he said.
"There should have been another boring machine ordered right at the beginning when the project was started."
Posted, updated
