West Gate Tunnel construction was delayed when contaminated soil was discovered. Credit:Joe Armao

Nearly 800,000 cubic metres of contaminated soil and rock will be dug out of the ground to build the state’s major transport projects, but experts warn that there is nowhere to dump it all.

An Environment Protection Authority auditor and expert engineers have forecast a landfill shortage unless more operators are licensed to accept contaminated soil extracted for the West Gate Tunnel, the North East Link and Metro Tunnel.

It comes as the discovery of contaminated soil during excavations for the West Gate Tunnel triggered delays in the $6.7 billion project – a problem that could cost about half a billion dollars to fix, sources close to the project said.

The Andrews government is understood to have agreed to chip in $50 million to help clean up the soil contaminated with asbestos and PFAS - the chemical that shut down the Fiskville CFA training college. However, a spokesman would not confirm this payment.