Snowy 2.0 tunnelling progressing despite challenges

Aerial shot of Talbingo adit, where TBM Lady Eileen Hudson is being reassembled for excavation of the tailrace tunnel (snowy 2.0)
Talbingo adit, where TBM Lady Eileen Hudson is being reassembled for excavation of the tailrace tunnel (Image: Snowy Hydro)

Hydroelectric generation company Snowy Hydro has given a progress update on construction of Snowy 2.0—the pumped-hydro expansion of the Snowy Scheme that will help underpin Australia’s transition to a renewable energy future.

The update comes in the wake of news workers were threatening to walk off the job over allegedly being served food with maggots and grubs.

Snowy Hydro issued a statement saying it was working with Snowy 2.0 principal contractor Future Generation Joint Venture (FGJV) to investigate workers’ concerns about food quality.

Related article: Snowy Hydro workers threaten walk-off over maggot meals

The company said progress was continuing to be made across multiple worksites.

“The Snowy 2.0 workforce of more than 2,200 is continuing to achieve milestones across a range of work fronts as they build the huge pumped-hydro expansion of the Snowy Scheme,” Snowy Hydro said in a statement.

“Despite the ongoing challenges faced by all large infrastructure projects, Snowy 2.0 continues to achieve progress across a large number of remote work fronts.”

At Lobs Hole, tunnel boring machine (TBM) Lady Eileen Hudson completed excavation of the 2.7km main access tunnel while TBM Kirsten had almost finished excavating the adjacent 2.9km emergency, cable and ventilation tunnel (ECVT).

At Tantangara, the project team was conducting works to stabilise encountered soft ground and enable TBM Florence to restart excavating the headrace tunnel.

FGJV is currently installing a slurry plant for the TBM that will mean the machine can switch from open excavation to a closed, pressurised mode. This will deliver stable excavation and efficient progress through the softer ground conditions, while enabling the TBM to switch back to open mode when in harder rock.

Image: Snowy Hydro

Stage two of the works to stabilise the ground in front and above the machine will involve ground improvement from the surface. Once the area is grouted, the depression will be backfilled and revegetated.

At Lobs Hole, in the main access tunnel, works are continuing on multiple drill and blast cross tunnels. These will link with the ECVT, where TBM Kirsten has tunnelled 2.8km and has reached the site of the underground power station cavern complex.

“This is a great milestone for Snowy Hydro as we now have access to the excavation site from both ends of the cavern, which will be one of the largest and deepest in the world,” the statement said.

TBM Kirsten is setting a global standard in tunnel boring technology, just as the original Snowy Scheme developed rock bolting techniques that are still used throughout the world today. The machine will soon be modified to excavate the inclined pressure shaft on a steep uphill angle.

Modifications include altering the levels of the TBM’s tanks and mechanical equipment so they are level when travelling up the 25-degree incline, and converting the walkways on the machine’s sides into steps and ladderways.

Related article: Snowy Hydro expansion faces delay to 2028

Meanwhile TBM Lady Eileen Hudson is being reassembled at the Talbingo adit with some new components including a cutterhead and shields. It will be launched into the mountain later this year to excavate the 6km tailrace tunnel, which will feed into Talbingo Reservoir.

Excavation of intakes at Talbingo and Tantangara is advancing steadily, along with the giant surge shaft on the Marica plateau that is already excavated to a depth of more than 20m.

Australia’s $5 billion expansion of the Snowy Hydro scheme is due for completion in 2028, and will provide the National Electricity Market with 2GW of on-demand generating capacity and 175 hours of energy storage.

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