Canals, Tunnels and Penstocks

Second tunnel excavation completed for 2 GW Snowy 2.0 project

Second tunnel excavation completed for 2 GW Snowy 2.0 project
(photo courtesy Snowy Hydro)

Snowy Hydro has achieved an important construction milestone, completing the second tunnel excavation, at Lobs Hole, for the 2 GW Snowy 2.0 pumped storage hydro project.

Snowy 2.0 includes the construction of an underground power station and about 27 km of tunnels within the Kosciuszko National Park in the Snowy Mountains region of New South Wales. Snowy Hydro said Snowy 2.0 is “critically important” and “will help underpin Australia’s transition to a renewable energy future.” This pumped hydro project will provide the National Electricity Market with 2 GW of on-demand generating capacity and 175 hours of energy storage.

The 2.93-km-long emergency, cable and ventilation tunnel (ECVT) has been excavated and lined with 13,140 concrete segments by tunnel boring machine (TBM) Kirsten. The tunnel has an internal diameter of 10 m. The ECVT provides secondary access with clean air to the power station complex and will be used permanently for ventilation and high voltage cables and intermittently for general access and maintenance.

Excavation of the adjacent main access tunnel (MAT) was completed in October 2022.

Snowy Hydro Chief Executive Officer Dennis Barnes said Snowy 2.0 was continuing to make solid progress, with around 6 km of tunnelling completed and drill and blast excavation of the power station cavern about to start. “The whole project team is excited to be moving into the next critical phase of construction,” he said.

Barnes said TBM Kirsten is being modified for a new task: excavating the inclined pressure shaft and lining it with concrete segments. “The shaft is 1.45km long and excavating a segment lined tunnel of this length at a very steep 47% incline using an 11-metre diameter TBM is without precedent internationally,” Barnes said.

Modifications to Kirsten include altering the levels of the TBM’s tanks and mechanical equipment so they remain horizontal when travelling up the incline and converting the walkways into steps and ladderways. A screw conveyor is being installed to extract excavated rock from the cutterhead to a sandwich conveyor system with face-to-face rubber belts that help constrain the crushed rock so that it can be transported down the steep slope without spillage.

There is a project workforce of more than 2,700 across four major worksites building Snowy 2.0.