ABSTRACT
The 250 MW Kidston Pumped Storage Hydropower project located in Queensland, Australia re-purposes an abandoned gold mine into a pumped storage hydroelectric scheme. At the heart of the scheme is an underground powerstation cavern complex located approximately 250m below ground surface. The main Machine Hall cavern housing the generating equipment comprises an excavation over 45m high, 21.5m wide and 85 m in length. Adjacent to this is the 15m wide, 13m high Transformer Cavern. Numerous other excavations including the Main Access Tunnel, construction adits, tailrace and intake shafts/tunnels, and vent shafts/tunnels also form part of the underground powerstation complex. An additional salient feature of the cavern design included a rock anchored crane beam supporting the 225T permanent electric overhead travelling gantry crane. This paper focuses on the excavation and rock support design and implementation for the cavern complex and rock anchored crane beam. Topics covered include the history and drivers behind the cavern complex development and design of the ground excavation sequence and ground support. Construction outcomes including modifications to the cavern design during construction to account for updated geological considerations and construction drivers are also discussed.
