Auckland’s Central Interceptor is transforming wastewater management, one tunnel, one pump, and one innovation at a time, with the help of a major player.
Auckland has faced a persistent issue: When it rains, it pours, often leading to overflow.
The city’s outdated wastewater system struggles during heavy rainfall, resulting in raw sewage contaminating rivers and beaches. However, a bold and comprehensive solution is emerging: the Central Interceptor, which is currently in development.
Stretching 16.2 kilometres, this is Auckland’s largest wastewater project, aimed at capturing and relocating overflows from urban regions. In an industry where infrastructure needs to endure, the project demonstrates how innovation, engineering, and strategic investments can transform wastewater management.
A tunnel tackling overflows
Auckland’s combined sewer system has struggled with stormwater inflows for years, often spilling sewage into the city’s harbours, which poses significant environmental and public health risks. Local waterways have been compromised, affecting marine life and recreational activities.
Watercare, the organisation overseeing the city’s water infrastructure, believes that the Central Interceptor, a major upgrade to the sewer system, will effectively reduce overflows by up to 80 per cent.
This project is seen as a crucial step in safeguarding Auckland’s water quality, improving the health of its aquatic ecosystems, and ensuring a cleaner, healthier environment for residents and visitors.
“This project will significantly reduce wastewater pollution, improving the quality of Auckland’s beaches and waterways,” a Watercare spokesperson said. “With a storage capacity of over 250,000 cubic metres – equivalent to 99 Olympic-sized swimming pools – the tunnel will help manage peak wastewater flows and provide long-term relief for the city’s sewer network.”
The tunnel will run from Grey Lynn to the Māngere Wastewater Treatment Plant, intercepting and redirecting wastewater that would otherwise contribute to environmental contamination. With Auckland’s population continuing to grow, the project is set to become a critical piece of infrastructure supporting sustainable urban expansion.
Engineering solutions for efficiency
While the tunnel is a massive feat, managing its wastewater requires robust pumping systems. That is where companies such as KSB play a role. For more than 150 years KSB has been at the forefront of wastewater pumping solutions, designing and supplying high-performance equipment for critical infrastructure.
“Effective wastewater management depends on reliable, clog-resistant pumps that can handle high volumes of mixed solids,” a KSB spokesperson said. “The right pump technology ensures wastewater moves efficiently through the system, reducing blockages and maintenance costs.”
At Pukekohe’s Pump Station 92, industrial wastewater containing long fibres had been causing frequent blockages. KSB said its open multi-vane impeller (D-max) retrofit resolved the issue, eliminating blockages and enhancing pump performance.
It believes that similar innovations in pump design can support large-scale wastewater projects.
The future of wastewater infrastructure
Major projects such as the Central Interceptor illustrate how significant investments can address persistent infrastructure challenges. Nevertheless, wastewater management solutions must keep evolving as urban populations grow and climate change heightens extreme weather events.
“Future-proofing wastewater networks means integrating smart monitoring, optimising pump performance, and investing in adaptive infrastructure,” the KSB spokesperson said. “As cities grow, the demand for efficient, sustainable wastewater solutions will only increase.”
With Auckland taking decisive steps to clean its waterways, other regions may consider similar deep-tunnel solutions to modernise wastewater networks. Innovation in engineering and strategic investment will remain essential to ensuring urban environments are resilient, sustainable, and prepared for the challenges ahead.
For more information, visit ksb.com
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