The Direct Pipe technology is being used to install a sea outfall pipeline for the modernisation of a wastewater treatment plant near Auckland, New Zealand.
The machine has been tunnelling its way through the New Zealand subsoil into the sea. Just under four months after launch, the site crew has achieved a successful breakthrough of the microtunnelling machine Blanche. With a length of 1,930m, contractor McConnell Dowell's project team has set a new distance world record with the Direct Pipe method.
Watercare's Army Bay Wastewater Treatment Plant project, on the Hibiscus Coast near Auckland, will create an additional 2.9km-long sea outfall. The pipeline connects the pump station with the discharge point, about 1km off the coast. This will significantly increase the capacity of the wastewater treatment plant.
Special attention is being paid to environmental protection so as not to impact the surrounding recreational and fishing area. Under no circumstances must the local flora and fauna be affected. This fauna includes kiwis, New Zealand's national symbol, which are under special protection.
Herrenknecht's patented pipeline installation method uses an AVN machine. The pipe string is attached to it and simultaneously inserted during the tunnelling process. This is done with the help of the ‘pipe thruster’. With pushing power of up to 750 tonnes, it thrusts the pipeline under the ground. Pipeline installation takes place in one step. In this way, the environmental impact is kept low and the landscape remains intact, said Herrenknecht.
The previous record had been about 1,496.5m. "The world-record breaking Direct Pipe drive at Watecare’s Army Bay project would not have been possible without the expert assistance and timely backup that Herrenknecht provided contractor McConnell Dowell right from tender preparation, through establishment of the plant to successful breakthrough,” said McConnell Dowell project manager Brent Whiting.
The new discharge at Watercare’s Army Bay Wastewater Treatment Plant is scheduled to go into operation early next year and will equip the facility for future population growth.