More than 500,000 tonnes of sandstone displaced by Sydney's Metro tunnel project will be used in the building of the new Western Sydney International (Nancy-Bird Walton) Airport.

Over 148,000 tonnes of the material has already been transferred from tunnelling sites at Chatswood and Marrickville since May, reports Western Sydney Airport CEO Graham Millett.

“This high-quality sandstone will be used as a high-strength foundation to support the construction of the runway, taxiways and roads on site,” says Millett.

“This is a great example of how we can make the most of Sydney’s infrastructure boom to not only save taxpayer funds but also cut down on waste.

“It’s about sustainability and efficiency, reusing resources and reducing carbon emissions."

One million cubic metres of earth have already been moved across the 1780-hectare site, but there's still much more to be done, with the building of the airport deemed one of the biggest earthmoving challenges in Australian history.

Sydney Metro aims to reuse 100 percent of rock crushed during the excavation process, which recently hit the halfway point.

Construction of the airport commenced in September 2018. Flights are set to start some time in 2026.

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