Pumped Storage Hydro

Snowy Hydro reports tunnel excavation by TBM Florence halted, again

Snowy Hydro reports tunnel excavation by TBM Florence halted, again
(photo courtesy Snowy Hydro)

Progress by tunnel boring machine (TBM) Florence in the headrace tunnel for the 2.2 GW Snowy 2.0 project slowed in very hard and abrasive rock on May 15, and the project ceased excavation by the TBM on May 16 due to rock pinching on the machine’s shield.

Snowy Hydro said it updated on TBM operations within 24 hours of the machine being stopped.

The Snowy 2.0 project team sought immediate advice from a specialist contractor with experience at other Australian projects with the same TBM situation. On May 21, the contractor began work using high-pressure water jets to remove the rock impinging on TBM Florence’s shield.

The timing for estimated recommencement of excavation will be determined on the successful removal of the rock, Snowy Hydro said.

The Snowy 2.0 pumped storage project is the largest renewable energy project under construction in Australia and will provide crucial deep storage central to the country’s renewable transition, according to a release. The value of Snowy 2.0 to the national electricity market has increased materially since the final investment decision in December 2018. Snowy Hydro said it would deliver an additional 200 MW or 10% capacity, bringing total capacity to 2,200 MW. Snowy 2.0 will provide 350,000 MWh of energy storage for 150 years.

This isn’t the first time the TBMs working on the project have been stopped. In December 2023, Hydro Review reported that tunnel work on the headrace adit at Tantangara for the 2.2 GW Snowy 2.0 pumped storage project was restarted after the New South Wales government approval for the project’s planning modification.

And in May 2023, the timeline and budget were reset for the project, with Snowy Hydro saying that one category of factors contributing to the schedule delays and likely cost increases was the impact of variable site and geological conditions, with the most impactful being the soft ground encountered that is delaying TBM Florence’s progress at Tantangara.