Snowy 2.0 – The next generation of hydropower in Australia

Snowy 2.0 is the next generation of the iconic Snowy Mountains Hydroelectric Scheme, and construction of this major pumped-hydro project is well underway. Once complete, the Scheme will provide 2000 megawatts of dispatchable, on-demand renewable energy and approximately 350,000 megawatt hours of large-scale storage to the Australian National Electricity Market.

Project

Snowy 2.0 Pumped Storage Project

Year

2017-2025

Location

Australia

Client

Snowy Hydro Ltd

27
of waterway tunnels
10.4
of access tunnels
2000
of on-demand power
350,000
of large scale energy storage

From a technical and engineering perspective, this project is at the forefront of international hydropower technology and design, attracting input and interest from global specialists across a range of fields. Snowy 2.0 also presents geographical and environmental challenges due to its remoteness and alpine location within (and below) the Kosciuszko National Park.

With over 27km of waterways designed to withstand extreme water pressures, Snowy 2.0 is a nationally and internationally-significant project being built by Snowy Hydro’s principal contractor Future Generation Joint Venture, a partnership between Italy’s tunnelling expert Webuild (formerly Salini Impregilo), Australian construction company Clough and US-Based Lane.

In 2017, SMEC was engaged by Snowy Hydro Ltd to conduct the feasibility study, subsequent reference design and tender assessment. Following the successful approval of the project, SMEC’s technical specialists have been engaged as the Owner’s Team for the project, providing technical advice from internationally recognised specialists and engineering support to help deliver this iconic and innovative renewable energy scheme.

Geotechnical report model revolutionising construction risk sharing
The Snowy 2.0 project site is situated within a complex alpine geological and hydrogeological area. This presents significant geotechnical uncertainties for construction, making it difficult to accurately predict construction time and costs.

At Snowy Hydro’s request, SMEC’s tunnelling and geotechnical specialists developed an innovative ‘balanced’ Geotechnical Baseline Report (GBR) which was incorporated into the construction contract. The GBR sets out geotechnical risk-allocation mechanisms with an aim for fair and balanced allocation of geotechnical risks between the owner of the project and the contractor.

Whilst the use of GBRs for risk allocation is a widely accepted practice in the tunnelling industry, SMEC has expanded upon this methodology to include a baseline of items of work, as suggested in the FIDIC Emerald book Contract form for Underground Construction, which are being used as the basis for remeasurement and adjustment of construction costs and time. In this ‘balanced’ GBR model, the time for project completion can be extended if the conditions are more onerous than described in the GBR or reduced if ground conditions are more favourable.

“Successful implementation of this ‘balanced’ risk sharing structure could be a game-changer for the Australian infrastructure industry, where traditional contract models have placed a heavy risk burden on contractors, resulting in premium construction costs and significant challenges for the industry’s long-term viability.”

– Alexandre Gomes, SMEC’s Chief Technical Principal – Tunnels and Underground

Improving these issues together with the incorporation of comprehensive risk management techniques during all project stages is believed to contribute to lower project costs by alleviating some of the complexities of project implementation and risks. This generates many benefits for all stakeholders, including the project owner, contractors and ultimately energy customers.

Collaboration to fast-track vital infrastructure
Snowy 2.0 is an outstanding example of how a complex project can be taken from the feasibility stage to the contract award over a period of approximately two years. It was in part achieved due to the flexibility SMEC was able to provide in delivering the feasibility study.

SMEC developed the feasibility study and reference design for the project involving tunnels, the powerhouse cavern complex, reservoir intakes, shafts and over 60 km of access roads. A 1,500-page project report and 280 design drawings were produced in a very tight timeframe. The feasibility study demonstrated that Snowy 2.0 is technically and financially feasible.

Snowy Hydro developed an Early Contractor Consultation (ECC) phase which involved pre-selected potential contractors to participate in a pre-tender process, with significant support from SMEC. The procurement process commenced in 2017 with the ECC phase running in parallel with the development of the reference design, providing involved contractors with early and advanced information on the project and associated challenges. SMEC advised Snowy Hydro during the technical review of tender submissions and the tender process concluded in April 2019 with the award of the main contract.

Unrivalled scale and complexity
Snowy 2.0 can only be described as monumental when considering the project scope, complexity and ambition. SMEC’s team of specialists have been engaged by the project owner, Snowy Hydro, to provide a team of internationally recognised specialists and engineering support to assist in the delivery of this iconic and innovative renewable energy scheme.

“The project includes 27km of waterway tunnels connecting two existing reservoirs, Tantangara and Talbingo. This allows the scheme to utilise approximately 700m of head difference by transferring water through the waterway tunnels and the six 340 MW reversible pump-turbines of the underground power station located approximately 750m below ground.” said Andreas Neumaier, SMEC’s Chief Technical Principal – Hydropower.

Three Tunnel Boring Machines (TBMs) will be used for the construction of the headrace and tailrace tunnels, main access tunnel, emergency, cable and ventilation tunnel and the inclined pressure shaft leading to the power station. The TBMs will each have an excavation diameter of approximately 11 m and will progressively line the tunnels with concrete segments produced at the purpose-built precast factory at Polo Flat in Cooma.

SMEC’s team is providing advice and support on critical project activities such as the Factory Acceptance Testing and Site Acceptance Testing for the TBMs, collaborative value engineering activities, critical review of design packages and on-site technical presence on behalf of Snowy Hydro during construction.

“With construction well under way, we are enjoying seeing all our hard work and planning coming to life,” says Andreas. “As one of the world’s most iconic hydroelectric projects, the next few years of construction are going to be monumental. It is a privilege and pleasure to contribute and be a part of Snowy 2.0”.

Project

Snowy 2.0 Pumped Storage Project

Year

2017-2025

Location

Australia

Client

Snowy Hydro Ltd

27
of waterway tunnels
10.4
of access tunnels
2000
of on-demand power
350,000
of large scale energy storage

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