Snowy Hydro has begun permanent concrete pouring almost a kilometre underground, marking a major milestone for the Snowy 2.0 pumped-hydro project.

More than 5,000 workers are building the underground power station at Lobs Hole in the Snowy Mountains. Excavation of the massive machine and transformer halls is over 90% complete, and crews are now preparing to install the plant’s six reversible turbines.

Over the coming months, workers will place more than 1,400 pieces of precast concrete to house the generating equipment, including transformers weighing over 400 tonnes each. All six turbines have already arrived in Australia.

Snowy Hydro CEO Dennis Barnes called the move into the fit-out phase “a landmark engineering achievement,” saying the project is building “some of the widest and deepest power station caverns in the world.”

Snowy 2.0 is designed to provide 350GWh of energy storage — equal to about 26 million home batteries — and has a planned 150-year operating life.