Construction of the Metro Tunnel Project’s five new underground stations and twin nine-kilometre tunnels requires the excavation of soil.
There are strict rules regulated by WorkSafe and EPA Victoria for how excavated contaminated material must be managed, including processes for identifying contaminants and classifying the material, as well as methods and procedures for safely removing them from site and disposing of them in accordance with environmental regulation. This is to ensure the safety of the community and our workers.
The Metro Tunnel Project has comprehensive soil management systems in place for:
Extensive soil testing is carried out prior to excavation.
This gives the project team a clear understanding of the types of soil to be excavated and how it should be removed from site for disposal. Further, regular sampling and testing will be conducted during excavation and removal of soil to satisfy Environment Protection Authority’s (EPA) Victoria Industrial Waste Resource Guidelines (IWRGs).
This is a requirement of the project’s Spoil Management Plan, which is prepared in consultation with the EPA and audited by the Independent Environmental Auditor.
Soil testing is undertaken by qualified specialists and verified.
Once soil has been tested, it is classified for disposal in accordance with EPA IWRG publications. Classifications include prescribed industrial waste (categories A, B, C) and fill material (soil with low to zero contamination and safe for re-use).
Categories are determined by the type and quantity of contaminants found. Category A being the highest level and Category C being the closest to fill material. Categories B and C material can be accepted at best practice landfills that are licensed by EPA to accept this material. Category A material requires treatment before disposal.
The aim of the categorisation framework is to improve treatment standards and achieve greater waste separation to help identify further avoidance, reuse or recycling opportunities.
The removal of category A, B and C soils are carefully managed. All classified soil will be separated out and disposed of in accordance with EPA guidelines and the project’s approved spoil management procedures.
The Metro Tunnel Project has a comprehensive Health and Safety Management Plan to ensure that members of the community and our project team are not exposed to hazardous materials.
Measures in place to ensure the safety of the community and project team prior to soil being removed include:
- Avoiding unnecessary handling of potentially contaminated soil
- Selection of equipment to manage dust
- Water carts to dampen the soil and manage dust
- Handlers to use personal protective equipment
- Stockpile management
The Metro Tunnel Project has a comprehensive Air Quality Dust and Lighting Management Plan that includes a monitoring regime for local air quality during work. The air quality monitors on site will provide real-time measurements of air quality, including dust generated during construction activity and soil removal.
During the removal of soil, safety measures will include exclusion zones and the use of water carts to dampen the soil and prevent dust. Soil is loaded onto trucks using machinery such as diggers, loaders and excavators. All trucks used to transport contaminated soil are licenced by the EPA. All trucks removing soil and material from the Metro Tunnel Project work sites are covered to prevent dirt and dust escaping. The project also aims to minimise the length of time that spoil is stockpiled on site.
Categories A, B and C soil will be separated out and disposed of in accordance with the EPA requirements and the Project’s approved spoil management procedures.
This material will be transported to a predetermined location and facility that is licenced by EPA to accept each of the corresponding types of waste.
Material classified as ‘Fill material’ under the EPA classifications can be re-used on site or transferred to other project sites where it can also be recycled. All soil handled and removed from site is managed by an EPA waste transfer certificate system. Each completed waste transport certificate is provided to the EPA.
Soil removal will be undertaken along pre-approved trucking routes.
Trucks transporting spoil from site will be remotely tracked and the project team will be alerted to any trucks that do not follow the designated routes.