Main access tunnel - On 11th October 2022 teams from Snowy Hydro and contractor Future Generation Joint Venture celebrated the completion of the excavation of its first tunnel for Snowy 2.0, with the Lady Eileen Hudson TBM reaching the location where the power station cavern will be built 800 m underground.
The 11-m diameter TBM has excavated 2.85 km to create the main access tunnel at Lobs Hole in the Snowy Mountains. The tunnel -10 m in diameter - has been lined with 1,422 concrete rings comprising 12,798 individual segments manufactured locally in Cooma. This is the first new major tunnel excavation in decades, since construction of the original Scheme.
The TBM is now being dismantled so it can be moved to the Talbingo adit where it will be reassembled with some new components for excavation of the 6km tailrace tunnel.
While dismantling of the TBM conveyor belt gets underway in the main access tunnel, drill and blast activities are ongoing to excavate 4 cross passages - linking the main tunnel to the adjacent emergency, cable and ventilation tunnel and tunnels to gain access to the power station complex, which will include a 251m-long, 52m-high machine hall cavern and 223m-long, 46m-high transformer hall cavern.
Headrace tunnel
Meawhile TBM Florence continues excavating the Snowy 2.0 headrace tunnel at Tantangara following successful reinforcement works.
The ground conditions encountered by the TBMs on Snowy 2.0 have been highly variable, ranging from soft, sandy ground to extremely hard rock. TBM Florence has been specifically designed to work with these variable ground conditions.
Consolidation grouting has been carried out around the perimeter of the headrace tunnel, and internally, the installation of steel ribs to reinforce the concrete segmental lining in the soft zone, have also been carried out to ensure stability and manage groundwater inflows. Additional instrumentation to monitor ground performance has also been installed.
Successful execution of the reinforcement works by Snowy 2.0 principal contractor Future Generation Joint Venture (FGJV) is enabling the TBM to carefully thrust off the segments and move forward.
Snowy Hydro expects variable and soft ground conditions to occur in sections of the very long 17-km headrace tunnel. Further ground improvement works – a typical tunnelling process – will be carried out where required so the TBM can safely advance.
Emergency, cable and ventilation tunnel
The TBM Kirsten is currently excavating the emergency, cable and ventilation tunnel and is setting a global standard in TBM technology. The machine will be adjusted to excavate the inclined pressure shaft, which has a very steep gradient - a 25-degree angle.
The Snowy 2.0 project a 2,000 megawatt pumped hydro expansion of the mighty Snowy Scheme - will link the Tantangara Reservoir (top storage) with the Talbingo Reservoir (bottom storage) through 27km of tunnels and a power station with pumping capabilities. This will enable water to be released for energy generation at times of peak demand and then pumped back to the top storage when there is excess renewable energy in the system, ready to generate again.
Snowy 2.0 will not only provide on-demand, quick-start generating capacity for the National Electricity Market (NEM), but a massive 350,000-gigawatt hours of energy storage.
Snowy Hydro and its Future Generation Joint Venture partners are working towards the successful delivery of Snowy 2.0.
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