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

Fast Facts:  Temporary repair of the collapsed portion of ARMCO pipe. Construction of three temporary shafts for the two tunnelling drives. 2100 mm ID stormwater pipeline will be installed by a Micro-Tunnel Boring Machine (MTBM) in two tunnelling drives. The MTBM will complete 220 m in the first drive and 50 m in the second drive. Decommissioning of the existing culvert once the new pipeline is connected.

The Greville Road Stormwater Culvert was identified as an emergency works project by Auckland Council Healthy Waters after the major Auckland floods in January 2023.

The urgent nature of this project meant that it was important for Healthy Waters to get this work completed immediately. McConnell Dowell was appointed to the Healthy Waters Pipelines and Tunnelling Panel in 2023. As a result, we were awarded the contract based on having a tunnelling team ready to go and also having worked with the client previously.

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

The existing Greville Road Culvert consists 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 where 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 McConnell Dowell will use 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 last year to begin the first phase of the project which was to unblock the culvert, the team successfully completed it in December 2023.

At the beginning of the year, 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 client has involved the project team from the get-go, allowing them to draft design elements parallel to the build. This collaborative approach with the client, 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.