An ageing sewer pipe crossing Auckland’s Hobson Bay was replaced with a three kilometre long, 3.7 metre diameter tunnel. A new six cubic metres per second pump station was construed in the Orakei Domain.
Aurecon was involved in all of the preliminary and detailed design for the project. Tunnelling technologies never before seen in New Zealand were applied to the project. Innovative approaches to vortex drop shaft arrangements, grit control and pump station design were required due to the challenging site conditions.
The upgrade provides for population growth in the area and will increase recreational opportunities in the bay. The tunnel’s extra capacity will reduce wet weather overflows, resulting in improved environmental outcomes.