The Central Interceptor is an expansion to the existing Auckland Wastewater network, aiming to increase capacity and reduce overflow. The project will connect Mangere Wastewater Treatment Plant to Point Erin.
The project scope includes:
- construction of a 16.2 km long tunnel with a 4.5 m internal diameter
- two 3.2 km long sewers, at a maximum depth of 70 m
- multiple drop shafts and access shafts
- expanding existing connecting sewers, chambers, control facilities and air treatment facilities, and
- construction of a wastewater pumping station.
A 1.5 km Grey Lynn to Point Erin extension was announced in 2023, bringing the new overall length of the tunnel from 14.7 kilometres to 16.2 kilometres.
Key Dates
| May 2018 | RFP Open |
| Mar 2019 | Contract Award |
| Aug 2019 | Construction Commencement |
| Dec 2028 | Expected Construction Completion |
Funding contributions
| User charges |
Procurement
| Successful Tenderer: | Ghella Abergeldie Joint Venture |
| Related contracts: |
PROJECT HISTORY
| May 2018 | RFP's opened for the Central Interceptor |
| Sep 2018 | Tenders were submitted for the project by four short-listed contractors. |
| Nov 2018 | A Joint Venture of Ghella and Abergeldie were announced as the preferred bidder for the project. |
| Mar 2019 | Watercare and AGJV formally signed the contract to deliver the Central Interceptor |
| Aug 2019 | Construction commenced on the Māngere Pump Station |
| Dec 2023 | WaterCare announces cost increase of NZ$204 million, approved by the Board on November 7. This covers construction of the tunnel to Tawariki St, Grey Lynn (due for completion mid-2026) and includes provision of $109m to address the impacts of ongoing inflation to the end of the project. This is in addition to the former cost increase to NZ$1.31 billion due to project scope changes, bringing the new cost of the project to NZ$1.523 billion. This costing does not include the additional 1.5km Grey Lynn to Point Erin extension, with this part of the project undergoing further planning. No cost for this extension was announced. |
| May 2024 | WaterCare announced that funding has been confirmed to extend the Central Interceptor wastewater tunnel by more than one kilometre from Grey Lynn to Point Erin, Herne Bay to reduce wet weather overflows and improve water quality in Herne Bay and St Marys Bay waterways and beaches. The funding was to be shared between Auckland Council and Healthy Waters, but Watercare did not confirm the quantum of funds committed. The Point Erin extension was expected to be commissioned in 2028 when it connects to an upgraded Herne Bay Trunk Sewer. Prior to the announcement of the extension construction on the project was expected to be complete in 2026. |
| Jun 2024 | WaterCare announced that construction had commenced on the Point Erin Extension. |
| Feb 2025 | Watercare announced that the 10.8 kilometre section from Blockhouse Bay east to May Road (Link Sewer C), and then south to Māngere Wastewater Treatment Plant is now operational. |
Estimated Total Cost
(2025)
Sector
Water & Sewerage
Procurement approach
Traditional Procurement |
Location
New Zealand |
Resources
