Innovative drainage solutions for ground-breaking Sydney Metro project

The Project

Sydney Metro, Australia's largest public transport project, is set to transform the way the nation's biggest city travels. With the aim of delivering 31 metro stations and over 66 km of new metro rail, the project is a monumental undertaking. Sydney Metro Northwest, the first stage of the Metro, is poised to become Australia's pioneering fully automated metro rail system.

The Challenge

The Northwest project entailed the construction of 15km twin tunnels and the development of eight new railway stations, accompanied by 4,000 commuter car parking spaces. The creation of five underground stations at Bella Vista, Norwest, Showground, Castle Hill, and Cherrybrook presented unique challenges. Consulting engineer Mott MacDonald was tasked with the detailed design of each underground station, with a specific focus on achieving long-term dryness. This required not only an effective waterproofing system but also hydrostatic pressure relief behind the waterproofing. Furthermore, the engineer sought a drainage system capable of combating the oxides present in the groundwater, known to obstruct traditional trenched pipe systems.

Our Solution

Recognising the successful implementation of Cavidrain Invert in Brisbane's Legacy Way Tunnel, Mott MacDonald approached the design team for assistance in designing the underground stations. Cavidrain Invert was chosen to create a floor-wide drainage network beneath the floor of each station. Th Cavidrain system allows for maintenance through jetting and the periodic addition of enzymes that dissolve oxide precipitates, ensuring minimal reduction in flow rate caused by mineral calcification. With its multiple interconnected flow channels, Cavidrain Invert offers excellent resistance to precipitate formation, enabling safe groundwater flow under the station box from tunnel to tunnel. The installation process involved laying Cavidrain Invert on the blinded rock formation and casting the concrete slab into the large cuspates. This allowed the construction of a drainage system that became as strong as the concrete itself.

The implementation of Cavidrain Invert delivered numerous benefits. Firstly, it significantly reduced installation requirements, streamlining the construction process. Secondly, the system enhanced drainage capacity, ensuring efficient water management within the underground stations. Furthermore, the solution minimises damage caused by mineral calcification, safeguarding the infrastructure's longevity. With a track record of reliability, Cavidrain Invert provided Sydney Metro with a trusted drainage system that met their project's unique demands.

Cavidrain played a pivotal role in Sydney Metro's ground-breaking transportation project. The innovative drainage solution, Cavidrain Invert, overcame complex construction challenges and delivered superior performance. Whether you're embarking on an underground construction project or seeking reliable drainage solutions, we are here to help.