Customer: Auckland Council Healthy Waters Contract: Construct Only Location: Downtown, Ports of Auckland

Fast Facts A new pipeline will be installed to increase capacity to allow for future growth in the upper catchment zones outlined in the Auckland Unitary Plan. Use of a three metre in diameter micro-Tunnel Boring Machine (m-TBM) to tunnel under Quay Street to a maximum depth of 20 metres. Installation of a 270 m inverted siphon pipeline. After completion, the pipeline will mitigate flood risk to the lower catchment area and surrounding properties.

The Ports of Auckland Outfall Upgrade Project, funded by the Auckland Unitary Plan, has been in Auckland Council’s pipeline for a number of years. And we are pleased to be constructing this important infrastructure for downtown Auckland.

The proposed design is an inverted siphon (U-bend shaped pipe). The horizontal section is 3 m in diameter and approximately 270 m long, installed within bedrock to avoid risks associated with construction within reclaimed land. This horizontal section connects two shafts, the inlet shaft south of Quay Street and the outlet shaft in the Ports of Auckland site that connects to a marine outfall.

Once complete, the new outfall will increase the stormwater network’s capacity and improve the resilience of downtown Auckland’s infrastructure. The improved network will also mitigate flood risk for properties in the downtown area, including Britomart train station.

This stormwater outfall upgrade draws on McConnell Dowell’s extensive track record in marine outfall construction using trenchless methodologies.

Work on this project includes:

• Service relocation works
• Piling works for both the outlet and inlet shafts
• Excavation works for both shafts
• Tunnelling under Quay Street to a maximum depth of 20 metres
• Chamber and outfall construction
• Culvert strengthening

This project is expected to be completed in early 2024.

Check out the video below of the completion of tunnelling.