15 November, 2023 By Nia Kajastie
The McConnell Dowell and John Holland joint venture has finished excavating the main access tunnel for underground works on Genex Power’s K2-Hydro, the first pumped hydro project in Australia in more than 40 years.
Renewable energy developer Genex Power has reached another construction milestone on its 250MW Kidston Pumped Storage Hydro Project, also known as K2-Hydro.
At the beginning of the month, the project’s engineering, procurement and construction (EPC) contractor, a joint venture between McConnell Dowell and John Holland (MDJHJV), finished drilling and blasting works on the scheme’s 1.5km main access tunnel.
The tunnel will serve as the permanent access point to the underground powerhouse cavern. It will also allow the JV to carry out further excavation works and ultimate fit-out works, including the installation of the two 125MW pumped hydro turbine units.
The main access tunnel had to be redesigned when water ingress was encountered during drilling works in September of last year. According to Genex, the project team came across an “unexpected geological feature”, which resulted in “a substantial inflow of water” into the tunnel.
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 has made the tunnel 436m longer, but according to the developer, it reduced the risk of the underground works.
Work could have continued on the original tunnel alignment by using grouting techniques to prevent water ingress through this zone, but Genex and MDJHJV concluded that this would have had an impact on tunnelling productivity and cost.
Tunnelling works on the realigned tunnel started in December 2022.
Genex CEO Craig Francis said: “We are extremely pleased with the way in which 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.
“[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 energisation later in 2024.”
The K2-Hydro project includes the conversion of a disused gold mine into a pumped storage hydroelectric power facility. Mott MacDonald and GHD have worked on delivering engineering services for the design of the project.
The A$777M (£404M) project remains on track for energisation in the second half of 2024.
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