Case Study - Northern Interceptor, Auckland

Case Studies
Northern interceptor

Wastewater line from Greenhithe to Hobsonville, Auckland


The amount of wastewater being collected and treated has increased significantly as Auckland’s population has expanded. Currently, wastewater from Massey North, Whenuapai, Hobsonville, Kumeu, Huapai and Riverhead
flows to the Māngere Wastewater Treatment Plant.

Why was the project commissioned

Commencing in January 2019, the $108 million Northern Interceptor project was undertaken to redirect this flow to the nearby Rosedale Wastewater Treatment Plant in Albany. Throughout the course of the project, Iplex supplied 7 kilometres of wastewater pipe.

What did the Iplex team offer that was special

The Iplex team always strives to deliver orders in full and on time. Working closely with all contractors and other parties involved in the project, Iplex carefully coordinated deliveries to site. This helped to ensure that all pipes
were delivered to the right location on a complex site at the right time. This was critical to eliminating delays and maintaining the momentum of installation.
Quality is a key component in all that Iplex do and the Northern Interceptor project enabled Iplex to showcase this. As part of the Watercare requirements,

Iplex measured and recorded the dimensions of each individual pipe and supplied this information to contractors prior to installation. This gave assurances that all pipe supplied by Iplex was within spec without the contractor having to undertake additional checks on each pipe. Each pipe was also sequentially numbered which enabled the contractor to track each length of pipe as it was being installed. This gave Watercare quick identification should any unexpected issues arise in the

The project’s benefits

The new northern interceptor pipeline will free up capacity at the Mangere treatment plant to cater for future growth. This allows with the Rosedale Wastewater Treatment Plant to have the capacity to manage the anticipated growth in the northern region through to the year 2070.