The pumped hydro project has faced several stoppages – the latest in February after an underground ventilation fan imploded. All underground work was suspended after the metal blades of the fan broke the fan casing and travelled 30-40m. No-one was injured.
Snowy Hydro says work has progressively restarted over the past two weeks. Operations for all three TBMs are under way, as well as power station drill and blast cavern excavation.
Above ground work was not impacted and continued throughout the period underground work was stopped.
In 2023, TBM Florence was halted for several months after a surface depression developed at the end of 2022. In the latest update, Snowy Hydro says it expects “the performance of our tunnel boring machines to continue to vary in line with ground conditions”.
The company says excavation and installation of rock support in the power station caverns is more than 35% complete. The transformer hall is now almost 50% excavated by volume and the machine hall is now 28m deep.
The drill and blast tunnels providing access to various levels within the caverns and other parts of the power station complex are more than 93% complete.
Excavation of the 266m-long collector waterway tunnel, which will pass water from the power station to the tailrace tunnel and onto Talbinsgo reservoir, is 80% complete.
For the upper reservoir intake, a 40m-high tower crane is assisting with construction logistics in the Tantangara intake pit, where the project’s first permanent concrete structures are being built. More than 6,600m3 of concrete has been poured so far.
For the lower reservoir intake, a total of 370m has been excavated from both ends of the connection tunnel. It is 825m long and will create a connection between the Talbingo intake structure and the tailrace tunnel.
A 70m-high tower crane has been installed to lift heavy equipment and materials in and out of the intake pit.
Excavation of the 240m-deep and 28m-wide Marica surge shaft has passed 151m. The shaft will provide water storage when Snowy 2.0’s power station starts up. When the station is shutting down, the Marica surge shaft will also provide pressure relief in the headrace tunnel. When completed, it will be one of the widest and deepest operational shafts in the world.
Excavation of the upper chamber for the downstream surge shaft is 68% complete. The shaft will be approximately 200m high and provide water storage when the power station starts up in pumping mode and pressure relief in the tailrace tunnel when the power station starts in generation mode.
TBM Florence, which is excavating the 17km headrace tunnel, which will connect the underground power station to the upper Tantangara reservoir, is more than 3km into the drive.
TBM Lady Eileen Hudson has completed 85% of the 6km tailrace tunnel, which will connect the underground power station to the lower Talbingo reservoir. The tunnel is now being used by workers to access the power station caverns.
TBM Kirsten has excavated 14% of the steep, 1.6km inclined pressure shaft connecting the underground power station to the headrace tunnel.
Preparations are also under way for the launch of a fourth TBM which is set to begin excavation by the end of this year.
In December last year, the NSW Department of Planning, Housing and Infrastructure approved Snowy Hydro’s application to deploy a fourth TBM to help protect the delivery timeline by boosting the project’s ability to tunnel through a complex geological fault zone.
