Canals, Tunnels and Penstocks

Tunnel work restarted for Snowy 2.0 pumped storage project

Tunnel work restarted for Snowy 2.0 pumped storage project
(photo courtesy Snowy Hydro)

Tunnel work on the headrace adit at Tantangara for the 2.2 GW Snowy 2.0 pumped storage project has restarted after the New South Wales government approval for the project’s planning modification.

Tunnel boring machine (TBM) Florence’s initial advance commenced last week. Tunnelling is being conducted in closed (slurry) mode, and progress is slow and steady, Snowy Hydro said. The company has engaged specialist experienced personnel to manage this process for the project.

Snowy Hydro Chief Executive Officer Dennis Barnes welcomed the milestone, which comes after a delay caused by soft ground conditions and emergence of a sinkhole above TBM Florence. “We were very pleased to receive the green light for tunnelling at Tantangara to recommence and to allow remediation of the subsidence area,” he said. “The conditions of approval were developed through the extensive review, public consultation and determination process, and will be strictly adhered to as we get back under way with excavation of the tunnel.

“The Snowy 2.0 delivery team is acutely aware of its responsibilities working in the sensitive environment of Kosciuszko National Park. We are focused on achieving excellent environmental outcomes throughout construction of this pumped-hydro expansion of the Snowy Scheme and critical infrastructure for Australia’s transition to renewable energy.”

The modification approval extends the project’s western boundary above the TBM at Tantangara. This will enable close monitoring of surface conditions as TBM Florence advances. Surface monitoring will continue until there is at least 100 m of overburden (distance from the TBM to the surface).

In preparation for the restart of tunnelling at Tantangara, extensive geotechnical investigations were carried out on the headrace adit alignment, along with ground improvement works.

In addition, at Talbingo, the Snowy 2.0 project continues to make good progress with excavation of the tailrace tunnel. TBM Lady Eileen Hudson has excavated about 1,000 m since its relaunch in July. Manufacturing of the six pumped hydro units is in full swing. And five of the six 153 tonne spiral cases have been manufactured, along with four draft tube liners and cones, three main inlet valves and other major power station components. One of the 13-m-long, 7.5-m-wide spiral cases was recently delivered to Lobs Hole, making a 442-km journey at night from Port Kembla.

Snowy 2.0 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.

In September 2023, Snowy Hydro revised its costs and completion date for Snowy 2.0. The revisted total cost to complete is $12 billion, with first power to be delivered in the second half of 2027 and December 2028 as the target date for commercial operation of all units.