Tunnel Boring Machine Returns After Installing Watercare's $22 Million Outfall
The 1.2 metre-wide TBM was secured to the keel of a 4m-long barge for its journey back to land.
The outfall is a key component of a broader infrastructure programme designed to support the projected population growth in Auckland's south-west, which is expected to reach approximately 30,000 people by 2050.
Watercare programme delivery manager Dave Kennerley says the outfall will initially carry highly treated wastewater from the Clarks Beach Wastewater Treatment Plant, which is currently being upgraded.
'The outfall has been designed and sized to support future population growth, as well as to store and discharge treated wastewater approximately 100 metres into the Waiuku Channel – a highly dynamic part of the harbour where it will quickly disperse.
'The wastewater that will be dispersed from the outfall will be of exceptionally high quality – and will only be discharged on the outgoing tide.'
Watercare project manager Jason Salmon says it took the TBM seven weeks to tunnel and install the outfall, which popped out at a receiving pit 10 metres under the sea mid-last month.
'After completing a seamless 240 metre drive – chewing through soil, weathered and formation rock to a depth of around 13 metres underground – the TBM sat on the seabed for two weeks.
'This allowed a crew of specialised divers to securely plug the outfall, preventing seawater intrusion, and safely secure the TBM to the underside of the pontoon.
'The pontoon is part of a larger fleet which includes three other hardworking vessels: The Combi, Iona and Tūhura, all of which can be seen working on the harbour from Clarks Beach.'
Salmon says the TBM is now undergoing crucial maintenance.
"The crew is focused on carrying out the piling work to establish a solid foundation for the 66 metre long diffuser.
'The Tūhura will drive seven large columns into the ground to create a sturdy base for the diffuser that will connect into the outfall the TBM has dug and installed.
'The role of the diffuser is to disperse treated wastewater through 22 rubber nozzles, which look like duck bills due to their shape.
'The duck bill design allows the periodic release of treated wastewater to flow out but stops sea water flowing in.'
Salmon says the outfall will be brought into service at the same time as the Clarks Beach Wastewater Treatment Plant upgrades, which are expected to be completed by June next year.
'People will be able to continue to watch the vessels hard at work from Waiau Beach, the Clarks Beach Gold Club or near the Clarks Beach Yacht Club until late 2025 when the outfall is complete.'
Try Our AI Features
Explore what Daily8 AI can do for you:
Comments
No comments yet...
Related Articles
Scoop
24-07-2025
- Scoop
Watercare Begins Tunnelling In Queen Street For $115m Wastewater Upgrade
Watercare's micro-tunnel boring machine (m-TBM) today begins its 600-metre journey under a stretch of Queen Street to lay a new wastewater pipe as part of the Midtown Wastewater Diversion project. Watercare acting chief programme delivery officer David White says the new 1.2-metre diameter pipe will connect to the Ōrākei Main Sewer and capture wastewater flows from the city centre. 'The start of tunnelling today is an important milestone in our $115m wastewater upgrade for the city centre. This project will reduce wet weather overflows into the Waitematā Harbour, improve the resilience of our network and allow for growth. 'We began construction in October last year and it's good to see tunnelling getting underway. We chose this method of construction as opposed to open trenching to minimise disruption to pedestrians and businesses.' The m-TBM was launched from a shaft at the junction of Queen Street and Mayoral Drive. Tunnelling will be done in two drives. It will bore through the ground at depths of 15 metres to a shaft at the corner of Wellesley Street East. 'Then, once we've inspected the cutterhead, the m-TBM will continue on, reaching the final shaft at the junction of Victoria Street East towards the end of the year,' White says. The m-TBM will lay the glass-reinforced plastic pipe in six-metre-long sections. A pipe-jacking method of tunnelling is being used in which hydraulic jacks braced against a shaft wall push pipes through the ground. 'We're doing everything we can to minimise disruption for residents and local businesses. All the activity will take place behind solid fencing, designed to minimise noise and dust, as well as keep pedestrians, motorists and construction crews safe,' White says. 'We've retained pedestrian access and installed signage to let people know businesses are still open.' Tunnelling is part of the first stage of the Midtown Wastewater Diversion project. Stage two of works is in design and will involve laying new wastewater pipes from Vincent Street to Greys Avenue carpark. The work is due to be completed in 2027. The project is part of Watercare's $13.8b infrastructure investment programme being delivered over the next decade to enable new housing, improve the reliability of services and protect the environment. It forms part of the Auckland Council group's midtown regeneration programme which is transforming the streets, spaces and underground infrastructure in midtown ready for when the City Rail Link opens and brings many more people into the city centre.
Scoop
24-07-2025
- Scoop
Watercare Begins Tunnelling In Queen Street For $115m Wastewater Upgrade
Watercare acting chief programme delivery officer David White says the new 1.2-metre diameter pipe will connect to the rkei Main Sewer and capture wastewater flows from the city centre. Watercare's micro-tunnel boring machine (m-TBM) today begins its 600-metre journey under a stretch of Queen Street to lay a new wastewater pipe as part of the Midtown Wastewater Diversion project. Watercare acting chief programme delivery officer David White says the new 1.2-metre diameter pipe will connect to the Ōrākei Main Sewer and capture wastewater flows from the city centre. 'The start of tunnelling today is an important milestone in our $115m wastewater upgrade for the city centre. This project will reduce wet weather overflows into the Waitematā Harbour, improve the resilience of our network and allow for growth. 'We began construction in October last year and it's good to see tunnelling getting underway. We chose this method of construction as opposed to open trenching to minimise disruption to pedestrians and businesses.' The m-TBM was launched from a shaft at the junction of Queen Street and Mayoral Drive. Tunnelling will be done in two drives. It will bore through the ground at depths of 15 metres to a shaft at the corner of Wellesley Street East. 'Then, once we've inspected the cutterhead, the m-TBM will continue on, reaching the final shaft at the junction of Victoria Street East towards the end of the year,' White says. The m-TBM will lay the glass-reinforced plastic pipe in six-metre-long sections. A pipe-jacking method of tunnelling is being used in which hydraulic jacks braced against a shaft wall push pipes through the ground. 'We're doing everything we can to minimise disruption for residents and local businesses. All the activity will take place behind solid fencing, designed to minimise noise and dust, as well as keep pedestrians, motorists and construction crews safe,' White says. 'We've retained pedestrian access and installed signage to let people know businesses are still open.' Tunnelling is part of the first stage of the Midtown Wastewater Diversion project. Stage two of works is in design and will involve laying new wastewater pipes from Vincent Street to Greys Avenue carpark. The work is due to be completed in 2027. The project is part of Watercare's $13.8b infrastructure investment programme being delivered over the next decade to enable new housing, improve the reliability of services and protect the environment. It forms part of the Auckland Council group's midtown regeneration programme which is transforming the streets, spaces and underground infrastructure in midtown ready for when the City Rail Link opens and brings many more people into the city centre.
Scoop
24-07-2025
- Scoop
Watercare Begins Tunnelling In Queen Street For $115m Wastewater Upgrade
Press Release – Watercare Watercare acting chief programme delivery officer David White says the new 1.2-metre diameter pipe will connect to the rkei Main Sewer and capture wastewater flows from the city centre. Watercare's micro-tunnel boring machine (m-TBM) today begins its 600-metre journey under a stretch of Queen Street to lay a new wastewater pipe as part of the Midtown Wastewater Diversion project. Watercare acting chief programme delivery officer David White says the new 1.2-metre diameter pipe will connect to the Ōrākei Main Sewer and capture wastewater flows from the city centre. 'The start of tunnelling today is an important milestone in our $115m wastewater upgrade for the city centre. This project will reduce wet weather overflows into the Waitematā Harbour, improve the resilience of our network and allow for growth. 'We began construction in October last year and it's good to see tunnelling getting underway. We chose this method of construction as opposed to open trenching to minimise disruption to pedestrians and businesses.' The m-TBM was launched from a shaft at the junction of Queen Street and Mayoral Drive. Tunnelling will be done in two drives. It will bore through the ground at depths of 15 metres to a shaft at the corner of Wellesley Street East. 'Then, once we've inspected the cutterhead, the m-TBM will continue on, reaching the final shaft at the junction of Victoria Street East towards the end of the year,' White says. The m-TBM will lay the glass-reinforced plastic pipe in six-metre-long sections. A pipe-jacking method of tunnelling is being used in which hydraulic jacks braced against a shaft wall push pipes through the ground. 'We're doing everything we can to minimise disruption for residents and local businesses. All the activity will take place behind solid fencing, designed to minimise noise and dust, as well as keep pedestrians, motorists and construction crews safe,' White says. 'We've retained pedestrian access and installed signage to let people know businesses are still open.' Tunnelling is part of the first stage of the Midtown Wastewater Diversion project. Stage two of works is in design and will involve laying new wastewater pipes from Vincent Street to Greys Avenue carpark. The work is due to be completed in 2027. The project is part of Watercare's $13.8b infrastructure investment programme being delivered over the next decade to enable new housing, improve the reliability of services and protect the environment. It forms part of the Auckland Council group's midtown regeneration programme which is transforming the streets, spaces and underground infrastructure in midtown ready for when the City Rail Link opens and brings many more people into the city centre.
