In a significant achievement for Snowy Hydro and its Snowy 2.0 project, a major milestone was reached last month as one of the project's three tunnel boring machines (TBM) marked its progress. TBM Lady Eileen Hudson crossed a pivotal milestone by commencing its second tunnel excavation after successfully completing the first phase.

TBM Lady Eileen's mission entails the excavation of a 6km tailrace tunnel that will connect the Talbingo Reservoir to an underground power station complex. This tunnel will play a crucial role in facilitating the flow of water for power generation, with the Snowy 2.0 project aimed at producing 2000MW of power.

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, said Snowy Hydro. The conveyor stacker, grout batch plant, and chiller plant were also relocated from the MAT portal to the Talbingo adit.

Before embarking on its underground voyage, the customary tradition of blessing was carried out for a safe journey under the watch of St Barbara, the patron saint of tunnelling and underground work. This ritual, observed at tunneling sites across the globe, took place in an onsite ceremony overseen by local parish priest Father Mark Croker, attended by Snowy 2.0 workers.

Following the blessing, TBM Lady Eileen was set into motion, its 378-tonne cutterhead making its mark on the rock face. This cutterhead, composed of 70 cutting discs, each weighing 290 kilos, has been designed to navigate the varying geological challenges of the 11m diameter tunnel. The TBM itself, measuring 137m in length and weighing a staggering 2,300 tonnes, operates as a mobile factory, orchestrating a synchronized dance of complex components.

A crucial aspect of this operation involves utilizing over 27,000 concrete segments manufactured at the Polo Flat, Cooma precast facility. These segments will line the tailrace tunnel, with the TBM housing essential equipment including a segment erector, segment feeder, segment cranes, and a sophisticated grouting system.

Incorporating advanced technology, the TBM is equipped with a guidance system that provides precise data to the machine's pilot, ensuring meticulous accuracy down to the millimeter. This data is closely monitored by Snowy 2.0's construction and engineering teams to ensure seamless progress.