Following last Friday’s announcement that Hi-Quality’s landfill site at Bulla would be the preferred site for storing soil excavated from the the West Gate Tunnel project, Roads & Infrastructure has gathered more details about how the soil will be processed.
The West Gate Tunnel Project is due to excavate three million tonnes (1.5 million cubic metre) of soil from the tunnel alignment over an 18-month period. It is estimated that there will be between 86 and 429 trucks per day transporting soil over the tunnel boring period, with approximately 229 truck per day average, and a peak of 429 being over a very short period.
“Thousands of workers have been making significant progress on the West Gate Tunnel Project and activation of the Hi-Quality site is a major step forward,” a spokesperson for West Gate Tunnel Project told Roads & Infrastructure.
“The tunnel entries and exits are well under construction and the tunnel boring machines are assembled. We look forward to tunnelling starting as soon as possible.”
According to the West Gate Tunnel Project spokesperson, the soil will be transported in specially covered and sealed trucks to the bays at the Hi-Quality site where it will be held for assessment and testing.
Once it is tested, the water will be drained off and treated through a water treatment plant at the Hi-Quality site, resulting in water that is within Australian Drinking Water Guideline levels.
The soil will then be classified and either contained on site in a purpose-built facility, disposed of to a licensed landfill or reused to support future developments or other projects.
The $6.7 billion toll road project is running at least two years late after detection of per-and poly-fluoroalkyl substances (PFAS), a material often found in firefighting foams, halted the tunnel excavation in early 2020.
With the announcement last week that CPB John Holland Joint Venture had recommended the Hi-Quality facility as the preferred site out of the three sites approved by Environment Protection Authority (EPA) Victoria, tunnelling is now expected to get underway as soon as possible.
“Testing shows the levels of PFAS in the groundwater from soil extracted by the tunnel boring machines is expected to be low and at safe levels for the community and the environment,” the spokesperson said.
“Testing indicates levels of PFAS between zero and 0.7 micrograms per litre – which is between detectable limits and much less than water that is safe to swim in.”
Hi-Quality had earlier informed Roads & Infrastructure it had undertaken rigorous assessments of its facility to address the concerns raised by the community. Among these, Hi-Quality will be using hard-stand and leach-proof lining on the containment bays, installing a globally recognised water treatment plant, and using robust lining in the containment cell.
EPA Victoria has assessed the potential environmental impacts and determined Hi-Quality’s Sunbury Eco-Hub can safely manage the material excavated from the West Gate Tunnel Project in accordance with strict regulations designed to protect the environment and the health of the surrounding community.