Calls for contaminated West Gate Tunnel soil to be treated rather than dumped in landfill

A scientist has questioned plans to send the West Gate Tunnel’s contaminated soil to landfill, arguing a more sustainable method that treats and recycles the waste should be adopted for future tunnelling projects.

The call comes as Transurban signs a multimillion-dollar deal with landfill group Hi-Quality to send the project’s 3 million tonnes of rock and soil to the facility in Bulla, in Melbourne’s north-west.

Work on the West Gate Tunnel has been delayed over how to deal with 3 million tonnes of contaminated soil.Credit:Luis Enrique Ascui

The $6.7 billion toll road is running at least two years late and faces claims of a $4 billion blowout. This is due to a protracted dispute over how to manage the project’s waste, some of which is contaminated with potential carcinogens called per- and polyfluoroalkyl substances (PFAS).

But Deakin University’s Will Gates, who specialises in mineralogy, has questioned the wisdom of sending the project’s rock and soil to landfill. The amount of waste dug up could fill the MCG and will chew up a significant portion of the state’s landfill capacity.

Associate Professor Gates points to a treatment now used at a facility in Dandenong called Renex, which heats the soil to 600 degrees in an industrial furnace – a process that removes PFAS chemicals.

His research, published in the Sustainability Journal, shows the treated soil could serve as a viable replacement for fine aggregate in concrete – for which there is a worldwide shortage.

This would avoid the need to dump large amounts of PFAS waste possibly dug up on future projects – including the North East Link and the Suburban Rail Loop – into landfill.

“This is a win-win for governments and the construction industry as well as the environment,” Professor Gates said.

While PFAS has been detected in the groundwater along the tunnel alignment, a new report confirms that contamination levels are very low.

The report by consultants AECOM prepared for Transurban and its builders shows that 80 per cent of groundwater borehole tests contain PFAS levels that are safe enough drink. Just 1 per cent is unsafe to drink or swim in, the report shows.

The project has only measured PFAS levels in groundwater, which may not necessarily reflect what is found in the rock and soil that is ultimately dug up, Professor Gates said.

But the groundwater results gathered on the project indicate that contamination levels were extremely low, he said.

“We have no idea how much of the soil is actually contaminated and what level of contamination it is,” he said. “If they lump it all together in a landfill, they have to treat all of the soil as if it was all contaminated.”

But the Victorian Environment Protection Authority is taking a cautious approach to PFAS due to emerging research about the dangers of the chemicals to human health and aquatic life, he said.

It means that waste containing small but detectable levels of PFAS being dug up on the West Gate Tunnel must be extensively processed and managed.

PFAS has been widely used over recent decades and can be found in household items such as cookware, cosmetics and dental floss.

The deal with Hi-Quality – understood to cost just shy of half a billion dollars – puts an end to a long planning and approvals process. But tunnelling on the project cannot begin until dozens of large holding bays are built on the site, which could take six months.

Once the soil is processed and tested, it will either be stored in a purpose-built facility at the landfill site, disposed of in a landfill cell or reused on other projects.

Transurban is not considering signing contracts with Maddingley Brown Coal in Bacchus Marsh and Cleanway Ravenhall, which also bid for the work. This means the project will not have a back-up dumping site.

Moorabool Shire Council is proceeding with legal action to ensure Maddingley is not later chosen as a back-up site. Hume City Council has also sued the Andrews government to stop the soil going to Hi-Quality.

A Transurban spokeswoman said the signing of a deal with Hi-Quality was a “significant step forward for the West Gate Tunnel project”.

“Hi-Quality Group’s Sunbury Eco-Hub was recommended by project builder CPB John Holland Joint Venture following its extensive technical assessment as a robust planning and environmental approval process to ensure the environment and surrounding community is protected.”

A government spokeswoman said the project’s “environmental effects statement identified low levels of PFAS in the groundwater in 2017 and the builder, CPB John Holland, also carried out testing that confirmed these low levels”.

“Transurban and its builder have had over four years to resolve this issue, and while we’re pleased they have finally made a decision, they need to get on with setting up the site and getting the tunnel boring machines going.”

A Hi-Quality Group spokeswoman said the facility would provide “world-class treatment … in line with EPA guidelines and industry best practice”.

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