July marked an exciting milestone for Snowy Hydro, the Snowy 2.0 project and for one of its three tunnel boring machines. Tunnel boring machine (TBM) Lady Eileen Hudson was the first machine to start tunnelling on the pumped-hydro mega project, the first to complete a tunnel and is now underway on her second tunnel excavation.

Snowy 2.0 senior project manager, Rodd Brinkman, is onsite at the Talbingo adit, where teams have been preparing to relaunch TBM Lady Eileen into the mountain.

The TBM will excavate the 6km tailrace tunnel to connect Talbingo Reservoir to the underground power station complex. Water used to generate 2,000 megawatts of power from Snowy 2.0 will flow out of the tailrace tunnel. Water also enters this tunnel when the power station is pumping.

After completing the 2.8km main access tunnel (MAT) in 2022, it has been a big task to disassemble and safely extract TBM Lady Eileen and reassemble her with new components before commissioning. The conveyor stacker, grout batch plant, and chiller plant were also relocated from the MAT portal to the Talbingo adit.

Before a TBM begins her journey underground, it is traditional for the machine and crew to be blessed for a safe journey under the watch of St Barbara, the patron saint of tunnelling and underground work. The tradition of blessing is acknowledged at tunnelling sites all over the world.

Local parish priest Father Mark Croker blessed the TBM at an onsite ceremony with many Snowy 2.0 workers in attendance. The machine was then switched on and began cutting the rock face. This is the fourth TBM launch for Snowy 2.0 and a major achievement for the Snowy Scheme expansion project.

TBM Construction Manager Derek Whelan manages all Snowy 2.0 tunnelling activities, as well as the TBM construction personnel. He was on-hand to run through Lady Eileen’s impressive components, including a new 378-tonne cutterhead.

The cutterhead is made up of 70 cutting discs each weighing 290 kilos that will excavate the varying geology of the 11-metre diameter tunnel. At 137 metres in length and weighing 2,300 tonnes, the TBM is a moving factory with many parts working together in a complex operation.

More than 27,000 concrete segments manufactured at the Polo Flat, Cooma, precast facility will be used to line the tailrace tunnel with the segment erector, segment feeder, segment cranes, and sophisticated grouting system all onboard the TBM.

The TBM is also equipped with a guidance system that provides data to the machine’s pilot, to the nearest millimetre. This information is mirrored above ground and monitored by Snowy 2.0’s construction and engineering teams. 

Snowy 2.0: Underpinning Australia’s transition to a renewable energy future