Burying the project’s 3 million tonnes of waste over an 18-month period is impossible “without exhausting existing capacity in the market”, the EPA said. Landfills in metropolitan Melbourne can accept about 650,000 tonnes of waste soil annually. Most of it is sent to Hi-Quality and Cleanaway Ravenhall.
The West Gate Tunnel’s boring activity will generate up to 11,000 tonnes per day, exceeding the current rate at which landfills can accept rock and soil – up to 70000 tonnes daily.
“In addition, the tunnel soil will be wet and requires a large area to spread out to aid dewatering prior to deposit in a cell – the space and infrastructure is not available at most landfills,” the EPA warned.
The Age and The Sydney Morning Herald flagged a landfill shortage in November last year due to large amounts of soil being dug up across major infrastructure projects the West Gate Tunnel, the North East Link and the Metro Tunnel.
Most waste dug up on infrastructure projects is typically considered “cleanfill” and can be reused on other projects.
But a new EPA threshold states soil containing more than four micrograms per kilogram of PFAS cannot be reused.
“The project has been unable to demonstrate that the spoil will meet this level,” the EPA said, meaning it must be tested and sent to landfill if the threshold is exceeded.
The amount of PFAS in the project’s tunnelling soil ranges from being virtually undetectable to 0.7 micrograms per litre – 10 times the level of drinking water, the EPA said.
Maddingley Brown Coal landfill is 800 metres from Bacchus Marsch Grammar, and the Parwan Creek, which feeds into the Werribee River, runs through the landfill site. Hi-Quality is close to Emu Creek.
The EPA found both landfills would contain contaminants leaching from the soil, but recommended Maddingley regularly remove leachate rather than store it in its holding bays, to avoid it leaking into Parwan Creek and causing legacy off-site contamination.
The project’s soil will spit out of a tunnel-boring machine onto a conveyor for transport to a purpose-built soil handling facility at Whitehall Street, Yarraville, before being sent to the landfills. There will be 15 truck trips a day for soil transportation, including during the night.
The state opposition will move to disallow in the Upper House new rules introduced by the EPA on tunnel-boring soil.
A government spokeswoman said: “The EPA’s approval sets strict requirements to protect the environment and the health of the community that these sites would have to meet if they are selected to take tunnel soil from the project.”
Timna Jacks is Transport Reporter at The Age