New Zealand's Largest Wastewater Project Relies on Leister

Success Stories31 Oct 2024
The Central Interceptor project, New Zealand's largest wastewater construction project, relies on Leister's reliable technology. Find out how Leister solutions are making a decisive contribution to the success of this infrastructure project.

Author: Anja Wieder, Corporate Communication Manager, Leister Group

Auckland’s Wastewater System for the Future

The impressive project includes a 16.2 km main tunnel under Auckland, running from the Māngere Wastewater Treatment Plant to Point Erin Park. The goal of the Central Interceptor project is to modernize the region’s wastewater systems, reduce overflows during heavy rainfall by 80 per cent and get the entire wastewater system ready for future population growth. Once the tunnel is completed in 2026, it will sit between 15 and 110 meters below the surface of Auckland. Watercare, the largest water supply and wastewater company in New Zealand, is in charge of the implementation of this important infrastructure project for the region. The municipal company operates over 15,000 kilometers of water and wastewater networks that serve the entire Auckland region.

The Challenge: Precise Welding in the Tightest of Spaces

The tunnel will be dug using a tunnel boring machine (TBM), especially developed for this project. This TBM has a diameter of 4.5 meters. The tunnel is composed of prefabricated concrete segments assembled into rings at the construction site. Each segment is 1.6 meters wide with an inner lining made of HDPE (high-density polyethylene) to prevent corrosion and leaks. An inner lining of HDPE Agru sheets was used to weld the 15-meter-long circular seams, which were welded with the corresponding HDPE welding rod.

Watertight, the company responsible for the welding work, chose the Leister WELDPLAST S2 and FUSION 2 extruders due to the scale of the project and the high demands. These tools offer the necessary performance at a low weight.

Reliability and Service: a Decisive Factor

The only certified Leister service and repair center in the country, Carr New Zealand Ltd (Carr NZ), regularly serviced the extruders without compromising Watertight’s productivity. Thanks to this well thought-out approach, it has been possible to maintain the 24-hour operation of the project without interruption.

The close collaboration between Carr NZ and Watertight was a decisive factor in the success of the project. Thanks to regular communication, problems could be solved quickly and work processes optimized. To meet the demanding schedule, Watertight assembled an international team of experienced plastic welders who received extensive training. Carr NZ’s support consisted not only of supplying the tools, but also providing targeted training on the handling and maintenance of the Leister equipment.

Outlook: Further Progress with the Central Interceptor

In June 2024, the project was around two-thirds of the way through its final phase. Thanks to Leister’s high-quality tools and the professional support from Carr NZ, the Watertight team is confident of successfully completing the project and making a major contribution to improving the infrastructure and quality of life in New Zealand.

This success story underlines how innovative solutions from Leister and strong partnerships can make a decisive contribution when it comes to challenging projects.

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