The harbour crossing will connect Memorial Park pump station to the Matapihi section of pipeline that has already been constructed.
A hole will be drilled deep underneath the harbour bed from Matapihi to Memorial Park, at a depth of up to 35m. Once drilling is complete, a steel casing pipe will be winched through from Memorial Park to Matapihi, and the polyethylene wastewater pipe will be pulled through and connected at both ends. Construction of this section began in February 2017 and will be completed the end of 2018.
An earlier plan was to lay the pipe in a scoured trench along the harbour bed alongside the rail bridge. This plan has been superseded by improvements in drilling technology. It is much less invasive to the harbour bed to drill the pipe deep under the harbour and this way there is no contact with the harbour waters.
Harbour crossing construction programme
Phase 1: Set up (Completed)
Work sites will be cleared at Memorial Park and Matapihi, with preparations underway for the arrival of heavy machinery. From late March, the end of Matapihi Road will be closed off to cars, with a new carpark and turning bay constructed about 200m up the road. Pipes will be delivered and welded together on site at Memorial Park.
Phase 2: Drilling (Underway)
Before the drilling starts, long steel pipes will be pushed into the soil below the harbour bed. These are outer steel sleeves that will protect the harbour when drilling starts. The hole will be drilled up to 35m deep underneath the harbour bed from Matapihi to Memorial Park. The sand removed from the harbour will be placed behind a low retaining wall at Matapihi, reclaiming a 5m section of land and protecting it from erosion.
Phase 3: Installation
Once the drilling is complete, a steel casing pipe will be winched through from Memorial Park. It is essential that this phase of work continues 24/7 to keep the momentum of the pipe moving. Once the steel casing pipe is installed, the polyethylene wastewater pipe will be pushed through inside. The steel casing will provide a protective layer between the wastewater pipe and the soils deep under the harbour.
Phase 4: Connection
The final sections of pipe will be installed through Memorial Park and Matapihi, connecting the harbour crossing to the Memorial Park Pump Station and to the Matapihi–Te Maunga section of the Southern Pipeline that has already been constructed.
Phase 5: Commission
The work sites will be cleared and returned to their original condition, or better. The pipeline will be monitored and tested, and will be operational the end of 2018.
Last Reviewed: 16/04/2018