06 Oct, 2023 By Belinda Smart
Australia’s beleaguered Snowy 2.0 renewable energy scheme is heading to the halfway mark as excavation of its central 250m-long underground power station cavern gets underway.
Snowy 2.0 is being delivered by Future Generation (FGJV) – a joint venture between Webuild, Australian firm Clough and an American subsidiary of Webuild called Lane Construction. It is the largest renewable energy project under construction in Australia and is designed to provide deep storage for Australia’s energy transition. When complete, the scheme, located in Kosciuszko National Park in New South Wales, will link the higher Tantangara Reservoir with the lower Talbingo Reservoir via tunnels through the Snowy Mountains.
It is centred around a subterranean hydroelectric power station 800m underground between the two reservoirs, which will generate renewable energy as water passes turbines in the tunnels and sending it to the grid.
The project has experienced cost hikes and delays since its inception. It was originally proposed in 2017 by Australia’s then prime minister Malcolm Turnbull as a AUS$2bn (£1bn) project, however by August this year its budget had blown out to AUS$12bn (£6bn). This followed several setbacks, from Covid-19 to supply chain delays and geotechnical challenges, that led to the announcement in May of a 12 to 24 month completion delay on the scheme.
The project’s fortunes appear to be on the turn however. In the latest progress update, project integration manager Paul Smith confirmed 40% of Snowy 2.0 was now complete, with excavation underway of the 250m-long underground power station cavern and tailrace tunnel. Meanwhile a tunnel boring machine (TBM) named Kirsten is being repurposed to excavate the inclined pressure shaft into the cavern that will later be lined with specially-designed, locally manufactured concrete segments.
The 1.45km long shaft will be excavated at a 47% incline using an 11m diameter TBM, an operation described by Snowy Hydro as “without precedent internationally.” Modifications to Kirsten include altering the levels of the TBM’s tanks and mechanical equipment so they remain horizontal when travelling up the incline and converting walkways into steps and ladderways. In addition, the installation of a screw conveyor will enable the extraction of excavated rock from the cutterhead to a sandwich conveyor system. This is fitted with face-to-face rubber belts to hold the crushed rock so that it can be transported down the slope without dropping.
Other ongoing activity on the project includes drill and blast to create 11 cross passages and construction tunnels and excavation of the 2.85km main access tunnel, lined with 13,000 locally manufactured concrete segments. Also being excavated is the 2.9km emergency, cable and ventilation tunnel.
Ravine Road, the steep 15km access road into the project’s main site at Lobs Hole in Kosciuszko National Park – the site of a former town and copper mine – is also undergoing a major upgrade. Infrastructure is also being built to support construction including the main yard workshops, worker campsites and 50km of access roads across three main worksites at Lobs Hole, Marica and Tantangara.
Meanwhile, other surface works include haulage of spoil, maintenance of site roads, environmental controls, main yard area activity, office facilities and directional drilling, as well as the building of the Talbingo intake tunnel. Progress on site includes Stage 2 earthworks with a recent blast covering an area of 4,500m2. About 10,000m3 of material is being removed as the excavation of the 104m high intake continues.
Snowy Hydro confirmed on 31 August that the scheme was expected to top AUS$12bn (£6bn), meaning its original fixed-price engineering, procurement, and construction (EPC) contract was deemed no longer “fit for purpose”. The promoter confirmed a “reset” including contractual amendments planned to enable closer collaboration between Snowy Hydro and FGJV.
Following the reset, the Snowy Hydro and Future Generation contractor teams are “now a single team, working in close collaboration to achieve full commercial operation by December 2028”.
An update on the project’s safety performance confirmed that as at September 2023, its 12-month rolling TRIFR (Total Reportable Injury Frequency Rate) was 2.97, below the target of 4.0.
It also reported a reduction in recordable and serious incidents on the project, with a focus on planning and a coordinated approach to safety management.
From an environmental perspective, Snowy Hydro confirmed construction of Snowy 2.0 would temporarily impact less than 0.1% of the Kosciuszko National Park, with short-term unavoidable impacts rehabilitated throughout the project, in accordance with environmental project approvals. This includes around AUS$100M (£50M) provided by Snowy Hydro to the offsets program for Kosciuszko National Park. Once operational, Snowy 2.0’s footprint within the park will be 0.01%.
Snowy Hydro confirmed that to date, four independent audits of the Snowy 2.0 project had been undertaken since project commencement. A total of 1,500 hours were spent annually to proactively monitor the 163 biodiversity sites, more than 200kg of native seed had been collected over three years for rehabilitation activities.
In addition, the project has to date entailed 27 heritage site excavations and more than 35,00 indigenous artefacts salvaged and being documented.
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