Keeping Soil Within the Circular Economy
The Metro Tunnel project is underway, and is generating significant volumes of wet soil. The soil is treated with lime at the worksite to dry it out. This has the unintended result of making the otherwise uncontaminated soil Category C soil due to the change in pH. The SUEZ-Ventia Joint Venture (SVJV) will accept the soil and treat it with ferric sulphate or citric acid to neutralise the lime and return its categorisation to Fill material. This means the soil can then be exported from the Soil Processing Facility (SPF) and reused, avoiding disposal.
Because of the volume and speed that the material is generated, SUEZ has proposed to EPA that a Contaminated Soil Holding Cell (CSHC) is constructed on the existing Cell 12C. The CSHC will be constructed in a similar manner to the previous Temporary Soil Storage Area (TSSA), with a bunded area and base made from clay. Run off from the CSHC will be directed into Cell 12C. If approved, the CSHC will be constructed very soon and will be used for approximately 18 months, to meet with the overall infrastructure project timeline. Exact volumes of material are not known due to the changing nature of the project, but it is anticipated that around 10,000 tonnes of soil could be delivered a month. Deliveries could take place any time, 24 hours a day. SVJV will communicate with the truck drivers to ensure impacts on our neighbours are minimised.
• Is the soil contaminated with hazardous chemicals?
No, the soil would be considered clean fill, it is only classified as Category C soil due to the addition of lime, which has changed its pH.
• Does the soil smell?
No, the soil is not expected to be odorous. SUEZ will continue to make daily odour rounds and will take action if odours are noted offsite.
• Will there be dust issues?
No, the material will be relatively moist when it is delivered. This will reduce the chance of dust creation. SUEZ will continue to do daily checks and will wet any material that is likely to produce dust. Note that the soil is virtually identical to the soil used as daily cover at the landfill.
• Where will the pH adjustment operation take place?
Under cover in the SPF building.
• Will any material stay on site?
No, material will be treated then exported for beneficial reuse.
• What is the impact on landfill cells?
There containment cell will have no impact on the operation of landfill cells.
• Once the Metro Tunnel Project is complete, what will become of the new cell?
The containment cell will be decommissioned.
• Does the soil get tested after treatment?
The soil will be tested by a third party to confirm the soil has been treated accordingly.