Customer:  Auckland Council Healthy Waters Contract: Construct only Location:  Pinehill, Auckland

Fast Facts:  Temporary repair of collapsed ARMCO pipe 2100 mm ID stormwater pipeline installed by micro-tunnel boring machine 3 temporary shafts 2 tunnelling drives: 220 m and 50 m long Decommissioning of existing culvert once new pipeline is connected

With an experienced tunnelling team ready to go, we took on this emergency works project for Auckland Council Healthy Waters after major Auckland floods.

The Corban Reserve Stormwater Upgrade in West Auckland was still underway at the time of the flooding, and our team had just finished the 713 m long tunnelling drive. With Healthy Waters as our customer, it was an easy transfer of skills and experience to Greville Road.

The existing Greville Road Culvert consisted of a 1,950 mm diameter ARMCO stormwater pipe that conveys flow from an inlet located within a basin north of Greville Road.

The pipe stretches across a key arterial road (Greville Road), that connects to the Northern Motorway and Albany Expressway, and under Rosedale Landfill. There, it connects into a 1,950 mm concrete pipe. The culvert had failed at the inlet on the northern side of Greville Road.

Although the initial scope was to excavate and remove the collapsed culvert and replace it with a temporary shaft, it was decided that this shaft could be designed and constructed to accommodate the permanent inlet at the same time. The reason for this solution was to avoid any reworking later on in the project, saving time in the construction programme.

What is unique about this project is that this is the first time we have used low-carbon pipes. The 92 pipes sourced through Hynds will avoid approximately 62 tonnes of CO2e emissions, which is a 16% reduction in the standard pipe range.

Work began in March 2023, with the first phase of the project to unblock the culvert. Our team successfully completed it in December 2023.

At the beginning of 2024, the project team mobilised the landfill site which accommodates the launch shaft for the MTBM. There are several risks to consider when operating within a landfill site, such as gas and leachate. These were similar working conditions that the team faced at Corban Reserve.

The collaborative approach with our customer, consultants and designers has already made a positive impact on the overall programme and provided a cost-effective solution.

This project is expected to be completed by mid-2025.