Successful ground stabilisation works and construction of a slurry treatment plant at Tantangara have been carried out by Snowy 2.0 teams prior to tunnel boring machine (TBM) Florence being able to restart excavation of the headrace tunnel.

Final commissioning tests are underway for the onsite slurry plant that means the dual-mode machine can switch from open excavation to a closed, pressurised mode. This method of excavation will enable stable excavation and efficient progress through softer ground conditions when required.

A significant testing regime has confirmed grouting and stabilisation of the loose material around TBM Florence has been effective. 

Additional stabilisation continues from the surface to solidify loose material above the machine and directly in front of the TBM cutterhead and the rock mass the machine is just short of.

We’re carrying out rotations of the cutterhead and minor advances of TBM Florence to ensure the machine is correctly positioned for final commissioning and to confirm the ground support activities are working.

Additionally we are working with NSW departments on environmental approvals for remediation of the surface depression above TBM Florence and to provide assurance that this will not reoccur. 

The plan is likely to go on public display in the coming weeks. 

The slurry treatment plant will process and separate materials used when the TBM is in closed excavation mode, including bentonite (an absorbent, swelling clay), which is placed into a tank and reused.