Tunnelling at the Snowy 2.0 project’s Tantangara site has been halted temporarily until Snowy Hydro can prove it will cause no further environmental damage, our sister publication Tunnels & Tunnelling International (T&TI) has reported.
Back in December, a depression developed on the surface above TBM Florence when it was transitioning from soft material into harder rock conditions as part of its excavation work on the headrace tunnel. Snowy Hydro initially stated that the tunnel's integrity had not been compromised, and tunnelling continued while efforts were made to rectify the surface depression. To ensure safety, a designated exclusion zone was implemented around the affected area.
Subsequently, Snowy Hydro temporarily halted the TBM's operations as plans for remediation were being finalized. Now, the New South Wales government has set forth specific conditions that must be met by Snowy Hydro prior to resuming tunnelling activities.
A Department of Planning and Environment spokesperson told T&TI: “Snowy Hydro must prepare a modification report demonstrating how the project can safely progress without further environmental damage. It will also need to include further geotechnical studies and detail how it will stabilise and remediate the site. That modification report will be placed on public exhibition once received for community feedback.
“Tunnel boring at the Tantangara location is on hold until the Department gives approval for operations to continue.”
In recent statements, Snowy Hydro CEO Dennis Barnes said that ongoing issues could lead to a delay of up to two years for project completion. These issues include the challenging soft ground conditions that halted tunnelling at Tantangara, and the presence of technically complex design elements requiring additional time for completion, resulting in increased construction costs. Moreover, global disruptions in the supply chain, inflationary pressures, and the impact of the Covid-19 pandemic have affected the availability and cost of skilled labor, materials, and shipping.
TBM Florence, which is the third and final tunnel boring machine utilized in the project, had already excavated approximately 150m and reached a depth of 30m when the depression, about 9m deep, appeared.
