New Zealand’s largest wastewater project, Central Interceptor, will deliver significant benefits to Auckland, providing additional wastewater capacity and helping to drastically reduce combined stormwater and wastewater overflows into our waterways.

This critical infrastructure project is an integral part of Watercare’s long-term wastewater strategy for the region which focuses on supporting population growth while protecting the environment.

The new 13km long, 4.5m wide tunnel will provide a more direct route for central Auckland’s wastewater flows, running underground from Western Springs, near Auckland Zoo, to the Māngere Wastewater Treatment Plant. Several link sewers and shafts along the route will collect and transfer wastewater into the tunnel for treatment and safe disposal. The tunnel’s massive 200,000m3 capacity will also increase network flexibility, enabling Watercare to store and control the flow rate of wastewater to the treatment plant.

Beca is working together with tunnelling specialist Ghella Abergeldie Joint Venture (GAJV) and Arup, providing wastewater, ground engineering, environmental and sustainability services to the $1.2B project.

Maximising opportunities for long term sustainable outcomes is an important focus. Our services include the integration of sustainability requirements into all project areas to support the eventual delivery of an Excellent rating under the Infrastructure Sustainability Council of Australia (ISCA) Infrastructure Sustainability Rating Tool. One key requirement is to complete a carbon footprint baseline for the project, from which carbon reduction initiatives from the design and construction phases will be measured.

Due for completion in 2025, the Central Interceptor will ensure the future needs of Auckland’s growing population are met in a safe, healthy, and sustainable way.

Image credit: Simon Runting 


Long tunnel



80% decrease

Approx. in wastewater overflow

Our team says

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 way.

Ann Williams

Geotechnical Services Manager

Our client says

Beca adds value to our Joint Venture, bringing deep local knowledge and expertise, especially in the areas of hydrogeology and consenting processes. They are also playing a critical role in setting up everything required to achieve the ISCA rating.

Francesco Saibene

Ghella Abergeldie JV Project Director

Our People

Ann Williams

Beca Technical Fellow - Engineering Geology and Hydrogeology

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Garry Macdonald

Business Director - Water

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Genevieve Smith

Principal - Sustainability Advisor

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