By Mike Foley
Florence the giant tunnel boring machine has again started grinding away under the Snowy Mountains, after spending two months stuck in rock while a recovery team blasted her free with powerful water jets.
The ill-fated Snowy 2.0 pumped hydro project has been beset with delays and cost blowouts, but for Dennis Barnes, chief executive of the Commonwealth-owned corporation, getting Florence back in motion is a ray of light at the end of the tunnel.
The headrace tunnel that Florence has been excavating, with the curved section where she became wedged in the background.
Florence got wedged in hard rock on May 16, when she was negotiating a curve in the tunnel, and it took a seven-week effort from a crack team of contractors with high-pressure water jets to blast rock that was pinching her shield.
“The high-pressure water blasting to remove the very hard rock ahead of tunnel boring machine Florence has now concluded, with the machine restarting tunnelling last week,” Barnes said.
However, given the previous track record, Barnes is wary of the potential for further delays.
“There are complexities ahead, as you’d expect with a unique project of this magnitude,” he said.
“We are closely monitoring Florence’s progress. We expect highly variable ground conditions ahead and the tunnel boring machine’s performance will continue to vary.”
Originally costed at $2 billion with a deadline of 2021, Snowy 2.0 is currently billed at $12 billion with a completion date at the end of 2028.
Florence is one of the project’s challenges, along with logistics, building and material cost blowouts.
The tunnel borer initially ground to a halt when it hit soft ground less than 100 metres into its work under Kosciuszko National Park last October and remained stuck for most of 2023.
In total, Florence has completed 850 metres of the 16-kilometre headrace tunnel at Snowy 2.0, boring up to 12 metres a day at top speed.
The headrace tunnel will connect the Talbingo reservoir to the powerhouse, where water from uphill in the dam will flow down and spin turbines to generate electricity.
The Snowy 2.0 pumped hydro project is an addition to the original Snowy Mountains Scheme, which opened in 1972 with 16 dams and 10 hydroelectricity projects.
The mega-pumped hydropower project will bring the scheme’s total generation capacity to 375,000 megawatts hours, or 2000 megawatts for an entire week, enough to power 3 million homes for that period.
The Tantangara worksite for the Snowy 2.0 project, under snow in the recent cold snap in the Australian Alps.
By comparison, Tesla’s big battery in South Australia can supply only 150 megawatts for 195 megawatts hours, meaning maximum power for roughly 1.5 hours.
Two other tunnel boring machines are whirring away on Snowy 2.0 with relative success. Lady Eileen Hudson has completed the 2.8-kilometre main access tunnel to the power station. It has completed three kilometres of the six-kilometre tailrace tunnel, which will connect the underground power station to the lower Talbingo reservoir.
Kirsten completed a 2.9-kilometre emergency, cable and ventilation tunnel and is now excavating the 1.6-kilometre Inclined Pressure Shaft, which will connect the underground power station to the headrace tunnel where Florence is working.
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