The West Gate Tunnel is a State Significant road project.
To build it, large amounts of soil will be dug up, and a facility is needed to receive and safely manage the soil.
Maddingley Brown Coal is proposing to develop Western Soil Treatment, a facility to manage the soil - known as spoil - some of which is expected to be contaminated with low levels of PFAS, a group of man-made chemicals.
The EPA has approved an Environmental Management Plan for the facility.
The project also needs planning approval, and a contract from the West Gate Tunnel Project's builders before it can proceed.
Western Soil Treatment will not receive any West Gate Tunnel Project spoil until the project’s builders award a contract.
Western Soil Treatment is situated within a State Significant Waste hub that includes a licensed Category C landfill.
Western Soil Treatment comprises two main areas.
The first is where covered, and sealed trucks would unload the soil into designated bays. The EPA has confirmed that the expected level of contamination is low (up to 0.7 micrograms per litre).
Trucks would be tracked by GPS from the tunnel site to make sure each load is unloaded in the right bay.
The soil will arrive at the site wet, like thick mud. It will be placed in specially constructed storage bays that are lined with layers of compacted clay, cement, lime and other materials to ensure they are watertight.
A sample from each batch of soil will be sent to a laboratory for testing on a daily basis. This testing will be conducted in line with national policies for managing PFAS and EPA regulations and requirements.
The soil will be held in the storage bays for a maximum of 21 days before being moved into the second area, a lined containment cell that is engineered to the highest safety standards.
The design of the containment cells has been upgraded and approved by the EPA, effectively doubling the strength of the liner system.
The level of contamination expected in the soil remains the same, but the strengthened containment cell adds an even greater layer of protection against already very low risks.
Water from the facility will be drained into a purpose-built pond. A treatment plant will remove traces if PFAS through a state-of-the-art filtration process, leaving clean water that meets drinking water standards.
A state-of-the-art wastewater facility will treat water to remove traces of PFAS.
Water from the wet spoil, storage bays and containment cell will drain into a large wastewater pond.
There, the wastewater will be passed through a filtration system that uses carbon filters
Any PFAS in the water will bond to the carbon filters. Full filters will be taken to a licensed facility for disposal.
This process leaves behind clean water that meets drinking water standards. This water will be used for onsite for dust suppression, forming a closed-loop wastewater treatment cycle.
Western Soil Treatment will be operated in line with strict EPA regulations.
The facility will be built and operated in line with the approved Environmental Management Plan.
The Environment Management Plan - which is available online here - details how the facility will receive, handle, analyse and dispose of the soil, including the removal of traces of PFAS chemicals from wastewater.
The Environmental Management Plan covers all aspects of the facility, including soil management and handling, sampling and analysis, wastewater treatment and disposal.
It also includes requirements for regular checks by an EPA appointed independent auditor.
For more information on the EPA’s regulation of the facility, visit the EPA West Gate Tunnel Community page.
Western Soil Treatment will not receive any West Gate Tunnel spoil until all environmental and planning approvals have been granted and a contract is awarded at the end of the tender process.
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