By Ashley Karen
The John Holland and McConnell Dowell JV has completed boring the main access tunnel for underground works on K2-Hydro of Genex Power, the first pumped hydro project in Australia, in over 40 years.
Genex Power, the renewable energy developer, has achieved another construction milestone on its 250MW Kidston Pumped Storage Hydro Project, also known as K2-Hydro.
At the beginning of November, a joint venture between McConnell Dowell and John Holland (MDJHJV), the project’s engineering, procurement, and construction (EPC) contractor, completed drilling and blasting works on the project’s 1.5km main access tunnel.
The tunnel will constitute the permanent access point to the underground powerhouse cavern. Also, it will enable the joint venture to carry out additional excavation and ultimate fit-out works, containing the installation of the two 125MW pumped hydro turbine units.
In September 2022, when water ingress was encountered during drilling works, the main access tunnel had to be redesigned. The project team came across an “unexpected geological feature” which resulted in “a substantial inflow of water” into the tunnel, reported Genex.
Genex decided to move the tunnel alignment away from this zone of high-quality but fractured rock that was charged with high-pressure water. This matter has made the tunnel 436m longer, but as the developer claimed, it diminished the risk of the underground works.
Work could have continued on the initial tunnel alignment by using grouting techniques to stop water ingress through this zone, yet, MDJHJV and Genex figured that this would influence tunneling productivity and cost.
It is worth mentioning that tunneling works on the realigned tunnel began in December 2022.
Craig Francis, Genex CEO, expressed: “We are extremely pleased with how the Genex and EPC contractor teams responded to the water ingress event last year, completing the redesign and recommencing production with minimal delay. This has limited the time and cost impacts of the water ingress event on the overall project.”
He continued: “[The most recent] milestone is extremely significant, as it enables Genex and its stakeholders to draw a line under one of the material outstanding risk items for the underground works. Importantly, it moves us one step closer toward commencing the power station fit-out works ahead of energization later in 2024.”
The K2-Hydro project incorporates the conversion of a disused gold mine into a pumped storage hydroelectric power facility. GHD and Mott MacDonald have worked on providing engineering services for the project’s design.
Nevertheless, the A$777M (£404M) project remains on track for energization in the second half of 2024.
