Australia’s largest committed renewable energy project is charging ahead, with advances on multiple fronts despite some temporary delays.
The Snowy 2.0 hydropower project involves linking two existing dams within the Kosciuszko National Park in New South Wales, Tantangara and Talbingo, through 27km of tunnels and building a new underground power station.
Water will be pumped to the upper Tantangara dam when the demand for energy is low, and released back to the lower Talbingo dam to generate energy when electricity demand is high. The project will utilise excess solar and wind energy to pump water to the higher dam, to be stored for later use. The water will be reused in a closed loop to minimise the project’s environmental footprint.
Snowy 2.0 will deliver 2200 megawatts (MW) of dispatchable, on-demand generating capacity and approximately 350,000 megawatt hours of large-scale storage to the National Electricity Market.
This is roughly enough energy to power three million homes over the course of a week.
Snowy 2.0 is the latest initiative from Snowy Hydro, an electricity generation company. Its portfolio of assets spans 16 power stations (including gas and diesel-fired peaking generators) and a pumping station, generating more than 5500MW of generating capacity across NSW, Victoria and South Australia.
The company provided an update on the most recent works at Snowy 2.0 in April. Trenchless Australasia breaks down the most important points.
Tunnel boring machines – TBMs
TBM Florence is excavating the 17km headrace tunnel, which will connect the underground power station to the upper Tantangara reservoir, with the machine now more than 3km into the headrace tunnel.
TBM Lady Eileen Hudson is excavating the 6km tailrace tunnel, which will connect the underground power station to the lower Talbingo reservoir. The machine has now completed 85 per cent of the tailrace tunnel, having already completed the 2.85km main access tunnel. The tunnel is being used by workers to access the power station caverns.
TBM Kirsten is excavating the steep 1.6km Inclined Pressure Shaft (IPS) connecting the underground power station to the headrace tunnel. The machine has excavated 14 per cent of the shaft, and Snowy Hydro expects the performance of its TBMs to continue to vary in line with ground conditions.
The NSW Department of Planning, Housing and Infrastructure approved Snowy Hydro’s application to deploy a fourth TBM in December 2024. The machine will help protect the delivery timeline by boosting the project’s ability to tunnel through a complex geological fault zone. Work to prepare for the launch of the machine is underway and is set to begin excavation by the end of 2025.
Power station caverns
Development of the Snowy 2.0 power station complex is progressing, with excavation and installation of rock support within the caverns more than 35 per cent complete.
The transformer hall is now almost 50 per cent excavated by volume and the machine hall is now 28m deep.
The drill and blast tunnels, which provide access to various levels within the caverns and other parts of the power station complex, are now more than 93 per cent complete.
In addition, excavation of the 266m collector waterway tunnels, which will pass water from the power station to the tailrace tunnel and onto Talbingo reservoir, is 80 per cent complete.
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 6600m3 of concrete have been poured so far.
Lower reservoir intake
A total of 370m has been excavated from both ends of the connection tunnel, which is 825m in length and will create a connection between the Talbingo intake structure and the tailrace tunnel.
A 70m tower crane has also been installed to lift heavy equipment and materials in and out of the intake pit.
Marica surge shaft
Excavation of the 240x28m Marica surge shaft has now 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. Once complete, it will be one of the widest and deepest operational shafts in the world.
Downstream surge shaft
Excavation of the upper chamber for the downstream surge shaft is 68 per cent complete.
This 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.
Restart after work stoppages
Underground work on Snowy 2.0 was progressively restarted throughout the last half of March. Operations for all three TBMs are now underway, as well as power station drill and blast cavern excavation.
Above-ground work was not affected and continued throughout the period that underground work was stopped.
Snowy 2.0 is expected to be operational in December 2028.
This article was featured in the June edition of Trenchless Australasia.
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