In January 2023 Carr New Zealand Ltd (Carr NZ) was approached by Auckland company Watertight to begin preparation for their work on Watercare’s Central Interceptor Wastewater Project in Auckland.
Our role was to provide plastic welding tools, welding accessories, servicing and expertise for this challenging infrastructure project.
The Central Interceptor is the largest wastewater civil works project in New Zealand history and consists of a 16.2-kilometre-long main tunnel from Māngere to Herne Bay intersected by two link sewers at Blockhouse Bay and Mt Albert. The Central Interceptor project will reduce 80 percent of wet weather overflows in waterways and beaches, improve resilience within the wastewater network and allow for population growth.
The project required extensive extrusion welding of all the tunnel segments installed by the Tunnel Boring Machine (TBM). The individual segments were 1.6m wide and the tunnel has an internal diameter of 4.5m. Each circular weld around the circumference of the tunnel is approximately 15 metres long.
The inner lining was an HDPE Agru sheet and welded with the corresponding HDPE Agru weldrod. A majority of the welding required two layers of welding to fill the voids between the joins and then finished with a 25mm overlap weld.
Given the scale, and size of this project, a range of Leister Extruders were considered. In the end Leister’s Weldplast S2 and Leister’s Fusion 2 were selected as the best tools for the job. The level of output and the physical weight of these tools was just what was required.
To maintain their 24-hour work schedule, Watertight carefully considered their tool requirements when purchasing their extruders from Carr NZ. Their robust equipment strategy has ensured smooth operations at the worksite, allowing tools to be rotated out for regular service and repair without disrupting productivity. As Leister’s only certified service and repair centre in New Zealand, Carr NZ has become Watertight’s one-stop shop for both its Leister tool purchases and all its servicing needs.
Constant communication between Carr NZ and Watertight has also been crucial to ensure that we can work together as efficiently as possible, address any issue promptly and enhance overall project outcomes as a result.
With the demanding work schedule for this project, Watertight needed to assemble a large team of experienced plastic welders from New Zealand and aboard. This diverse team, with their varied backgrounds, required comprehensive training to ensure everyone understood how to manage and maintain the specialised tools, with Carr NZ again being able to provide assistance in this area. Preparation is always essential to successfully tackle a project of this scale and complexity, and their commitment to training again highlights Watertight’s commitment to quality and efficiency.
As of June 2024, the project is about two thirds completed.