The work and the technique: Snowy 2.0 Hydroelectric Project

Technically speaking, Snowy 2.0 is a pumped storage scheme: two water reservoirs placed at different heights, with the pump station in the middle, allowing the power plant to recycle the water used to drive its turbines. The water in the upper reservoir passes through the station, driving turbines that generate electricity before flowing into the lower reservoir. At this point, the water is pumped back into the upper basin to start the process again.

The project, awarded to a joint venture led by the Webuild Group and starting in 2019, will connect the existing Tantangara (upper reservoir) and Talbingo (lower reservoir) dams, 29 km apart, by excavating a series of tunnels. The work includes building an underground power plant, a hydroelectric station equipped with a pumping system around one kilometre underground, access roads and other necessary infrastructure, including a prefabrication plant in Cooma and a facility to produce concrete segments for tunnel construction.

Three mechanical TBMs (Tunnel Boring Machines) specially designed for Snowy 2.0 will be used for excavation activities. One of these is among the first in the world to dig over a range of very challenging variable slopes and very steep angles, with downhill gradients of up to 9% (five degrees) and uphill ones of up to 47% (25 degrees).

The first TBM was commissioned in March 2021, after its transport from Port Kembla and on-site assembly. Named “Lady Eileen Hudson” and 11 metres in diameter, the TBM's task is to dig the 2.6 km main access tunnel to the power station. The TBM will then be disassembled and reassembled at the Talbingo portal where it will dig the tailrace tunnel.