The Bogong Power Development Project, awarded to McConnell Dowell as a design and construct (D&C) contract by AGL Southern Hydro, is the largest hydro power project constructed in Australia in 25 years. It consists of a network of tunnels and shafts and the construction of a new underground hydro electric power station in a picturesque national park near the Victorian ski fields at Falls Creek. The power station forms part of AGL Southern Hydro’s strategic energy framework for the supply of green peak demand power. It will harness the Rocky Valley and Pretty Valley branches of the East Kiewa River and existing water resources released from the Mackay Creek Power Station to generate 140MW of renewable power.

The project includes:

• 6.5 km of 5 m diameter hardrock tunnel constructed using a tunnel boring machine;
• 1.3 km of drill and blast tunnels;
• 250 m of 5 m diameter shafts;
• 5,000 t penstock liners;
• power station construction and installation of two 70 MW turbines.

The power station is an underground structure. The excavation of the station box is top-down excavation utilising secant pile walls, rock anchors and excavation in rock to some 25 metres below the surface. Approximately 30,000 cubic metres of material will be excavated. The power station foundations will require more than 10,000 cubic metres of concrete.  Pivotal to the success of the power station construction is the co-ordination of the mechanical equipment including turbines, generators, draft tubes and inlet valves and scroll casings. These massive individual pieces will require installation as the power station is constructed from the depths of the excavation.

MacDow's engineers worked with our consultants in extensive value engineering workshops to reduce the price by A$30 million. The team realigned the tunnels and developed innovative materials-handling techniques for all tunnel rock.

Effective community involvement and engagement is also a critical success factor. Bogong Village houses an Outdoor Education Centre and is a significant bush trekking area.  McConnell Dowell have been supportive in enhancing the services of both this centre with improved outdoor activities areas, and by providing upgrading walking tracks in the areas surrounding the project. Public and community interaction groups are regularly convened and awareness programmes keep stakeholders and local authorities fully informed. The sustainability focus of the project has also been extended to the disposal of the tunnel rock spoil. The local Alpine Shire using this material to upgrade local roads in the area, particularly the high plains road to Omeo from Falls Creek.

Being constructed in an alpine national park has meant the project has been highly scrutinised by AGL Southern Hydro and the EPA – and the results have been exceptional. To quote AGL Southern Hydro’s Project Manager John Arnold:

“The statutory authorities cannot speak highly enough about the work done by McConnell Dowell. The work they are doing is being used as a benchmark for future projects.”