Northern Interceptor

This pipe will redirect wastewater from the north-west to the Rosedale Wastewater Treatment Plant.

Phase 1: 2019–2020
Status: Construction

Construction for Phase 1 began in January 2019. This is combined with the watermain improvement works across the upper Waitematā Harbour.

What’s happening?

As the north-west of Auckland expands, so does the amount of wastewater we collect and treat. The Northern Interceptor is a new wastewater pipeline that will be built in stages, depending on how fast the population grows. 

Currently, wastewater from Massey North, Whenuapai, Hobsonville, Kumeu, Huapai and Riverhead flows to the Māngere Wastewater Treatment Plant. The new pipe will redirect this flow to the nearby Rosedale Wastewater Treatment Plant in Albany. Future stages of the pipe will be constructed depending on population growth in the area.
auckland wastewater and water network map

Greenhithe Road traffic management
In mid-to-late June 2019, we will start trenching over Tauhinu Road towards Greenhithe Road. A one-way traffic system will be established along Greenhithe Road as works progress. Stop-go traffic management will be in place during the day, with temporary traffic lights in operation at night. There will be no street parking adjacent to the work site. Working hours will typically be from 7am to 6pm, Monday to Friday, and from 8am to 5pm on Saturdays.

Question and answer about the project

Why is that section of road fully closed?
At approximately 710mm in size, the Northern Interceptor wastewater pipe is big. To safely install this pipe we need specialist equipment and adequate space to work. Maintaining the safety of road users, pedestrians and our workers is of utmost importance.

Traffic control is unavoidable in carrying out this work. If one-way traffic was maintained using stop-go/traffic lights, this would still result in the same minor delays as taking a detour. We timed the detour and it is approximately 4 minutes in duration. It's important to note that one-way traffic would have extended the time needed to complete the works.

What actions have been taken to make the road closure period as short as possible?
A full road closure allows the works to progress as quickly and safely as possible. If the works progress as planned, we are hoping to allow one-way traffic management once the most critical section is installed. This would be possible by placing temporary plates on the open excavation sections and would take place about two weeks after the works commence.

How are we informing the Greenhithe community of the works?
VMS digital sign boards are currently in place and are the most effective way to communicate with road users. Updates have regularly been placed on this page and Facebook.
Furthermore, a number of residents (who are known to Watercare), schools, day cares and businesses were emailed following confirmation that construction could be carried out under COVID-19 Level 3 and in line with the approved traffic management plan. Information was also provided to the Greenhithe Residents Association, communicated to the Greenhithe Facebook page and letters were delivered to those people living along the affected section of Greenhithe Road and Wainoni Heights.
How will emergency services operate
Throughout the project we have been and will continue to be in regular contact with emergency services. We are working with the fire service to address any issues and put in place actions to mitigate any concerns. We are carrying out essential public works for the common good and we thank the community for their patience.

Horizontal directional drilling at the Causeway

Using advanced tunneling technology we've successfully completed our drilling from the Causeway under the harbour to Rahui Road reserve and installed a new wastewater pipe under Waitematā Harbour. To get an idea of the scale of the work, press play on the video.

What are the benefits?

  • The new pipeline will free up the Māngere treatment plant to cater for future growth.
  • The Rosedale Wastewater Treatment Plant has the capacity to manage the anticipated growth in the northern area up until 2070.

Any questions?

Please contact us:
Phone: (09) 442 2222 
Email: [email protected]

More information 

Northern Interceptor project area updates (June 2020)
The Horizontal Directional Drilling (HDD) process
Newsletter (Winter 2019)
Northern Interceptor route map
Newsletter (March 2016)
Requirement and designation process: a guide

Application documents, including decision and conditions

Combined assessment of alternatives - final for consent
Consent drawings
GBWD and causeway - Volume 1 - AEE
Greenhithe Bridge Northern Interceptor conditions s133A 10 Feb (1)
Greenhithe Bridge Watermain and Northern Interceptor - decisions final (1)
NH2 Stage 5a causeway earthworks combined drawings (1)
Technical Report A - Earthworks, erosion and sediment generation - final
Technical Report B - Soil, sediment and groundwater contamination - final
Technical Report C - Groundwater - final
Technical Report D - Ecological assessment  - final
Technical Report E - Arboricultural assessment - final
Technical Report F - Traffic assessment - final
Technical Report G - Construction noise and vibration - final
Technical Report H - Coastal process report - final (1)
Technical Report I - Landscape and visual assessment - final (1)
Technical Report J - Heritage impact assessment - final

Northern Interceptor AEE

Technical Report A - Assessment of noise effects - final
Technical Report B - Construction vibration assessment - final
Technical Report C - Assessment of arboricultural effects - final
Technical Report D - Archaeological assessment - final
Technical Report E - Coastal processes report - final
Technical Report F - Assessment of landscape and visual effects - final
Technical Report G - Construction traffic assessment - final
Technical Report H - Ground contamination assessment - final
Technical Report I - Ecological assessment - final
Technical Report J - Groundwater and settlement assessment - final