Source: Auckland Council
The preliminary work for Watercare’s Midtown Wastewater Upgrades begins next week.
Three midtown sites are being prepared and shafts are being built, ready for a tunnel boring machine to be lowered into the ground in 2025. The machine will reach depths of up to 14.5 metres and tunnel a distance of 585 metres below Queen Street.
These underground wastewater upgrades are a key component of the Auckland Council group’s midtown regeneration. The programme is preparing streets, spaces and infrastructure for the City Rail Link, which will bring many more people into the city centre to live, work, study, visit and do business.
The upgrades will renew the workings of the city centre’s century-old pipes, enable the consenting of a pipeline of commercial and residential apartment developments, and help protect the region’s precious Waitematā Harbour.
Chair of the Transport, Resilience and Infrastructure Committee Councillor Andy Baker explains that this wastewater project is essential for Auckland’s future resilience.
“Midtown will become an even more popular place for people to live beyond 2026 when the City Rail Link’s Te Waihorotiu Station is operational. With these important works complete, we will have increased the capacity of our wastewater system and upgraded the quality of our pipes in midtown.
“It is vitally important for us to futureproof the area ahead of the population growth expected in midtown, and we are taking steps also with this work to reduce the risk of wastewater overflows entering the Waitematā Harbour during heavy rain.
“I want to emphasise that Watercare has sited the shafts away from shops and businesses, synchronised the works with other construction in the area for maximum efficiency, and ensured that traffic in Queen Street continues to operate.
“As the safety fences go up around three localised shafts next week to enable this work, we want to remind everyone that midtown continues to be open for business,” Councillor Baker says.
This wastewater work around Queen Street, delivered by Watercare and supported by Auckland Council, is scheduled to be complete by December 2026.
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Q&A
What else is being upgraded?
While stage one of Watercare’s Midtown Wastewater Upgrades will increase wastewater capacity, crews will also take this opportunity to reline the Victoria Street section of the Ōrākei Main Sewer. Doing this work during Stage 1 of the pipeline installation eliminates the need for Watercare to return to Victoria Street to do this critical work later. Stage two is in the design phase and will involve laying new wastewater pipes from Vincent Street to Greys Avenue carpark.
Why is this work essential?
The Midtown Wastewater Upgrades support the Auckland city centre’s planned residential and commercial growth, reduce the risk of future overflows into the Waitematā Harbour and safeguard and increase resilience of midtown’s wastewater network.
What are the problems we’re solving?
Currently, the wastewater and stormwater in the midtown area combine into a single pipe which feeds into a large pipe called an interceptor, which takes flows to Māngere Wastewater Treatment Plant for processing.
Combined networks are designed to overflow during rainfall events at designated overflow points rather than back flow up your toilet or sink.
The focus of the Midtown Wastewater Upgrades is to redirect most of the wastewater away from the combined network and channel it through a dedicated 1.2km pipeline.
The project also involves reconfiguring the current wastewater network to better use under-utilised pipes.
After the Midtown Wastewater Upgrades are complete, overflows from the combined network will become less frequent after heavy rainfall events.
How will the tunnel boring process work?
A large portion of the pipeline will be installed using a method called horizontal directional drilling (HDD). The benefit of using this method is that it will get the job done more safely, faster, and with a higher quality result. Horizontal directional drilling is also better for the environment than open trenching as it lessens the impact on surrounding critical assets and reduces fractures and soil disturbance. This method is also less disruptive for the community as there is much less digging up of the street.
Read more about the city centre’s transformation here.
