Trenchless Australasia sat down with WSP’s work group manager for water William Chan to chat about the Queen Street wastewater project in Auckland’s city centre.
It’s more than just a pipe,” Chan said. “Positioning a large pipe beneath one of New Zealand’s busiest streets, 20m underground, will be no easy feat.”
“Chock-a-block with existing underground utilities, thousands of residents, local businesses, pedestrians, and constant traffic, the site was a challenging place to engineer and construct in.”
The client is Watercare, a major utility company that provides water and wastewater services to 1.7 million Aucklanders.
Carried out as part of Watercare’s Enterprise Model, the project prioritises collaboration and early contractor involvement (ECI).
It cleaves to Watercare’s 40:20:20 vision, which aims to achieve a 40 per cent reduction in built carbon, 20 per cent cost savings, and 20 per cent improvement in health, safety and well-being.
WSP planners and engineers are responsible for the project’s design and consenting, with Fulton Hogan as the construction partner – both Watercare Enterprise Model partners – with sub-contractor McConnell Dowell advising the design of tunnelling works along Queen Street.
The new pipe will complement Queen Street’s existing wastewater system, reduce wastewater discharges into the environment, and provide increased capacity due to growth in the city’s Aotea precinct. With more intense rainfall predicted with climate change, the 1200mm-sized pipe will also help mitigate wastewater overflows.
Chan said the project team is currently focusing on the consent and detailed design phases, where the use of digital technology is playing a crucial role.
“Project services, design, contractor setups, and temporary works design will be integrated into a digital platform. This means the project team can test and challenge design ideas in a virtual environment before implementing them on-site – for a more efficient and safer outcome,” he said.
When construction starts early next year a hybrid combination of pipejacking and direct pipe methodologies will be used, allowing the entire 600-metre-long pipe to be installed in one uninterrupted drive.
“This trenchless technology will be instrumental in navigating a complex underground environment that includes old valleys and rock formations. And the use of push-fit sections will reduce construction time and costs,” Chan said.
The project is a golden opportunity for people like graduate water engineer Fawaz Farook to grow their professional capability. Having been at WSP, he’s been involved in the project’s hydraulic design, BIM implementation for a digital twin, temporary works design, programme management, and stakeholder coordination.
With its careful planning and innovative project strategies, Chan said construction plans can be optimised, conflicts minimised, and work done with a minimum of fuss and disruption.
“By collaborating as part of Watercare’s Enterprise Model, the project is set to achieve significant value-adds. Reducing the size of the drill shaft at the Victoria Street intersection, for example, will minimise service diversions.”
Plus, health and safety will be improved by eliminating the need for human entry into live sewers. Well-coordinated efforts with other works in the area are expected to result in reduced costs and less disruption.
“We’re proud to be helping modernise Queen Street’s wastewater infrastructure to meet the demands of a growing city – while delivering lasting benefits to the community and environment,” said Watercare project manager Yukie Wang.
“This project represents all that is good about an ECI and epitomises the benefits of close collaboration between client, designer, contractor and specialists,” Jeremy Gordon, Fulton Hogan project manager said.
This article featured in the October edition of Trenchless Australasia.
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