Auckland water authority Watercare has said that work on its new 1.8km outfall tunnel – the longest direct pipe drive project in the world – is a third of the way through and on target.
The Herrenknecht tunnel boring machine (TBM), named Blanche, has driven the first 600m of the tunnel from the Army Bay Wastewater Treatment Plant.
Watercare projects manager John McCann said: “We are very pleased with progress. There have been no major hitches and the German TBM is working really well. The decision to use the direct pipe method of tunnelling was the right one.”
The pipeline, which expected to be completed in November this year, will replace an existing one which has reached the end of its design life.
The direct drive pipe tunnel will take the outfall from the wastewater treatment work below land and will be connected to an immersed subsea pipeline that will carry the discharge out into the Tiri Channel close to the existing discharge point.
The next milestone on the project will come on 26 July when the first section of new outfall pipe is towed from Kaiaua to Army Bay. The pipe will be floated into place before being submerged into position on the seabed.