More than 1 million cubic metres of contaminated soil – including some waste that falls under the most toxic classification – will be dug up during the first stage of the Suburban Rail Loop, government documents show.
Category A waste, which is the highest reportable level and includes soil that can contain toxic gases and cannot be handled without treatment, will be largely found around the site of a former gasworks in Cheltenham.
Early works at a Suburban Rail Loop site in Burwood.Credit: Paul Jeffers
Construction workers on the 26-kilometre underground railway in Melbourne’s east will also handle large quantities of acid sulphate soil, which has the potential to become sulphuric acid if exposed to the wrong conditions.
But the project should avoid unearthing large quantities of the notorious “forever chemical” PFAS, which triggered a three-year delay of the West Gate Tunnel project.
The Suburban Rail Loop Authority (SRLA) is investigating ways to treat and reuse the contaminated soil, but it has sparked fresh concerns over how the city manages the growing amount of excavated material from its Big Build and two mega projects, including the North East Link and SRL, valued at more than $60 billion.
Freedom of Information documents obtained by the state opposition and seen by The Sunday Age show that the Suburban Rail Loop East – from Cheltenham to Box Hill – will excavate 4.6 million cubic metres of soil across its tunnel, stabling facility and stations.
The spoil management report, used to inform early planning for the project and its environmental effects, shows about 106,000 cubic metres of this will be “reportable priority waste”, which has the strictest level of controls from the Environmental Protection Authority (EPA) Victoria. It does not anticipate reportable amounts of PFAS.
The most toxic classification is known as Category A. The documents expect 6000 cubic metres of this waste to be found in the area near the future SRL station at Cheltenham, around the site of a former gasworks.
This type has not previously been identified in early assessments of the West Gate Tunnel or North East Link and as recently as 2019 there were no facilities available to handle it.
Across the first stage of the rail loop, another 917,000 million cubic metres of soil containing acid sulphate is expected to be excavated. The documents note this soil can be reused but must first be treated at an EPA-registered facility because it has the potential to oxidise and produce acid if not handled correctly.
Sir William Fry Reserve, where a Suburban Rail Loop station will be built. Credit: Paul Jeffers
The EPA and Independent Environmental Auditor have reviewed the Suburban Rail Loop Authority’s plans for managing acid sulphate and other spoil.
Waste experts in 2019 forecast a significant shortage in landfill space to store the state’s most hazardous soil amid pressure from major projects such as the Metro Tunnel, West Gate Tunnel and the now underway North East Link. At the time, there were no facilities for Category A but more sites have since come online.
Victoria’s efforts to increase the state’s capacity have become more vital with the addition of the rail loop’s first stage to the infrastructure pipeline.
Tunnelling is expected to begin in 2026, unearthing 1 million cubic metres of contaminated soil. This figure rises to 1.6 million cubic metres when accounting for “bulking” – additional increases in size as the soil is transported.
SCAADA Group, a project management company that does soil remediation and management, says the market for handling high-category waste is tight but that the sector remains sustainable.
Managing director Dale Smith said the greater challenge was what to do with lower level soil that could not be immediately reused.
He said this meant looking more closely at remediation – which could be cheaper than expensive options such as driving soil to landfill – and a circular economy for soil to make it reusable.
“As we developed from the middle of Melbourne outwards, we pushed a lot of the contaminants out to an area we thought we would never catch up to,” Smith said.
“The problem is now those areas are now being caught up to with development.
“We’re cleaning soil, pretty much daily, to try to make it reusable. But some of the newer issues that are starting to pop up are simply the management of waste that we’re finding on sites, and how we give that a new life.”
Smith said tight construction contracts did not always account for unexpected remediation costs.
He said developers and builders were more aware of contaminated land but needed to accept the need for contingency measures when projects didn’t go smoothly.
“The cost is pretty reasonable nowadays … There are numerous companies that know what they’re doing,” he said.
Waste Management and Resource Recovery Association of Australia chief executive Gayle Sloan said there was capacity in the system, but said there should be clear standards for the safe recycling of excavated dirt.
“We’ve got to have a regime that enables us to use that soil again, in a similar purpose,” she said.
“We’ve got to make sure it’s safe, but we have ongoing challenges meeting chemical levels [requirements] when it’s just literally taking soil from one place and putting it back into the same purpose elsewhere. That’s probably one of our greatest challenges nationally.
“We should be able to use it and not be sending that to landfill.”
During the loop’s environmental effects process, it was noted that Kingston Council had concerns about whether there were enough facilities for disposal of contaminated soil. The state agreed to ensure there were ongoing investigations into landfill capacities to address these issues.
Opposition spokesman David Davis said there would be significant disruptions around Suburban Rail Loop sites.
“Residents will face the incessant movement of trucks carrying tunnel spoil. Much of the spoil will be toxic to be carried to licensed treatment facilities,” he said.
A SRLA spokeswoman said the vast majority of soil excavated would be safe to reuse for the project and on others.
“We will work with contractors to identify the most appropriate way to re-use, treat and manage soil safely and within existing capacity,” she said.
An EPA Victoria spokesman said they would assess how the project complied with its regulations for soil
“EPA will undertake enforcement in all phases (early works, construction and operation) of the project as necessary,” he said.
“EPA will advise the project on matters relating to air pollution, contaminated land, surface and groundwater, noise and vibration, greenhouse gas emissions and resource efficiency, land use and planning and human health.”
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