Transurban and the state government were warned by the state's environmental regulator three years ago in a West Gate Tunnel report that there were "emerging concerns" about PFAS contaminants in soil and flagged a tightening of restrictions.

The parties were also told in the 2017 report, commissioned to assess the environmental impact of the project, there was a shortage of possible dump sites for PFAS soil.

Premier Daniel Andrews and the Minister for Transport Infrastructure Jacinta Allan this week. Credit:Jason South

The Andrews government's flagship infrastructure project collapsed into turmoil this week when builders John Holland and CPB Contractors threatened to walk away over the discovery of PFAS soil and an impasse over where it could be processed and buried.

In its submission to the West Gate Tunnel's environmental effects statement, the Environment Protection Authority warned that PFAS substances – a group of potentially dangerous contaminants which shut down a CFA training college in Fiskville – would be increasingly regulated, due to emerging health and ecological concerns.