Start–finish: 2019–2025
Location: Western Springs to Mangere
Status: Detailed design
What’s happening?
The Central Interceptor is a wastewater tunnel that will run between Western Springs and the Mangere Wastewater Treatment Plant
The tunnel will run underground for 13 kilometres and will be at a depth of between 22 and 110 metres, as shown below.
It will cross Manukau Harbour at about 15 metres below the seabed. Along the route it will connect to the existing wastewater network, which will divert flows and overflows into the tunnel.
What are the benefits?
The Central Interceptor will:
Provide for future growth of Auckland
The Central Interceptor is needed to ensure there is sufficient capacity in the network to meet planned population growth and development in Auckland. Without this, more overflows into the waterways and harbours will occur.
Reduced overflows to the Waitemata and Manukau Harbours
During wet weather, the overall wastewater network currently overflows to the Waitemata Harbour at more than 200 points and to the north-eastern part of the Manukau Harbour at 14 points. The Central Interceptor is expected to reduce the annual average overflow volume by 80 per cent.
Reduced environmental risk for the Manukau Harbour
The lower section of the Hillsborough Tunnel and Manukau Siphon is estimated to have a residual life of between 15 and 25 more years. If it fails, it could mean continuous untreated wastewater discharge into the Manukau Harbour for an unknown period of time from over 200,000 customers, including industrial flows presently treated at the Mangere Wastewater Treatment Plant.
Watch a video explaining the project:
Any questions?
More information
Fact sheet
Hearing panel’s decision
Media release
Resource consent application
Project works evidence
Contractors' information
Minutes of the Meola Creek Community Liaison Group meeting
Minutes for meeting 10 May 2017
Minutes for meeting 14 December 2016
Minutes for meeting 4 July 2016