LanTrak, Cleanaway and Wyndham have only processed pre works...

LanTrak, Cleanaway and Wyndham have only processed pre works PASS to date as the TBMs for the main project have not even been assembled yet. The Lend Lease contract and EES is different to the John Holland pre works contract as I'm sure you are well aware of.

What exactly do you mean by "stabilise"?

My understanding is that the EPA lime treatment costs far more than $10/ton and I can't find anyone in Melbourne that does this. There is a site in Stawell that treats PASS with lime but they charge in the vicinity of $150 per tonne. I find it hard to believe that a landfill will only charge $10/t to "stabilise" PASS but charge you $35 to dump a truck tyre

Companies that comply with the EES and have an EPA approval will get the PASS.
EPA have a legal and moral obligation to Victorians to ensure this happens.

20.7.3 Acid Sulfate Soil and Rock

As noted in Section 20.5.3, there is a high likelihood of Melbourne Metro encountering potential and actual acid sulfate soil and acid sulfate rock. This means that a high proportion of the spoil excavated from the tunnels (about 221,000 m3) would be expected to be acid sulfate soil or acid sulfate rock. The potential impacts from disturbing acid sulfate soil and acid sulfate rock include human health impacts, adverse effects on aquatic environments and the corrosion of concrete and steel infrastructure from acidified groundwater.
Acid sulfate impacts would be managed in accordance with EPA guidelines and the Industrial Waste Management Policy (Waste Acid Sulfate Soils). This would include implementing an environmental management plan that includes:

• Identification of the location and extent of any acid sulfate soil and rock (primarily Fresh Melbourne Formation rock and Coode Island Silt) within the project boundary
• Assessment of the potential environmental risks of disturbance
• Identification of suitable sites for the re-use or disposal of any acid sulfate
  material.
  Prevention of acid generation is the preferred management option. However, a number of off-site waste management options are available for treating acid sulfate material extracted during tunnelling activities, where prevention is not possible. These options include:
  • Treating spoil with limestone
  • Inhibiting oxidation of pyrite in spoil by underwater disposal or by
    encapsulation within a water saturated engineered cover
  • Preventing leaching of pyritic spoil by encapsulation within a long-term containment system designed to limit infiltration.
    Further testing would be undertaken during the project’s detailed design and construction phases to determine the most effective management option.
    Acid sulfate soil can only be disposed of or re-used on sites that have an EMP approved by the EPA or at a landfill with the appropriate licence. On-site re-use of this material is not considered practical.
• https://metrotunnel.vic.gov.au/__da...20_Contaminated-Land-and-Spoil-Management.pdf