Construction to start on Auckland’s Central Interceptor

New Zealand’s largest ever wastewater project is officially underway, with the Central Interceptor construction contract signed between Watercare and the Ghella Abergeldie Joint Venture on 14 March.

Figure 1 – Members of the Beca team at the Central Interceptor contract signing, from left; Lesley Hopkins, Ann Williams, Genevieve Smith and Garry Macdonald.

Beca will be working with the Joint Venture and Arup on the $1.2B, six-year project, bringing the best in Wastewater, Ground Engineering and Environmental Services expertise to an initiative that will define the future of Auckland’s wastewater infrastructure.

The Central Interceptor is a wastewater tunnel that will run 13 kilometres underground from Māngere Wastewater Treatment Plant to Western Springs, near Auckland Zoo and a further 2 kilometres on to Grey Lynn. 

Figure 2 – Route of the Central Interceptor. IMAGE COURTESY OF WATERCARE

Connecting to the western end of the Ōrākei Wastewater Interceptor, the tunnel will collect wastewater via link sewers and drop shafts and provide a more direct route for much of central Auckland’s wastewater flows.

In a design and construct contract, Beca will be involved in a host of different aspects of the project’s planning, key relationships management and consent compliance management, as well as designing for sustainability, instrumentation and monitoring, hydrogeology, stormwater management, traffic management and commissioning.

“Being part of the Central Interceptor team is an incredible opportunity to contribute to a ground-breaking project, ensuring the future needs of Auckland’s growing population are met in a way that is safe, healthy, and sustainable,” says Ann Williams, Beca Geotechnical Services Manager. 

Watercare chief executive Raveen Jaduram said the project would allow Aucklanders to enjoy cleaner beaches by substantially reducing wastewater overflows during storms.

"In older parts of central Auckland, wastewater and stormwater flow into a combined network of pipes. When it rains, stormwater overwhelms these pipes, which are designed to overflow into waterways," he said. "We want everyone to be able to enjoy clean waterways, beaches and estuaries – that's why we're building the Central Interceptor."

Figure 3 – Route of the Central Interceptor. IMAGE COURTESY OF WATERCARE

At 4.5 metres diameter, the Central Interceptor will be one of Auckland’s largest wastewater tunnels and one of the biggest wastewater projects ever undertaken in New Zealand. It is expected to reduce the volume of wastewater overflows in wet weather into the Waitematā and north-eastern Manukau Harbour by over 80 per cent.

It will reduce environmental risk and add to benefits we’re seeing from the biological nutrient removal upgrades at the Māngere Wastewater Treatment Plant – a project that Beca recently completed the commissioning of. 

The joint venture of Ghella Abergeldie combines more than 150 years’ experience with large-scale tunnelling and wastewater projects across the globe.