The tunnel boring machine (TBM) called ‘Blanche’ at out Army Bay Wastewater Treatment Plant has travelled 600 metres— a third of the way on its journey from the plant to the transition point, 500 metres into the sea.
The machine isn’t travelling fast, between 28-35 mm per minute and has covered almost two kilometres so far, but it’s doing a great job of cutting through the ground, laying a new wastewater pipe.
Watercare projects manager, John McCann says everything is on track: “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.”
Local politicians were recently invited to see progress. Councillor John Watson was pleased to see the operation was not having any adverse effects on the local wildlife as the treatment plant is located inside Shakespear Regional Park—an environmentally sensitive area: “While we were there, there were birds flying around at the same time the big drilling machine was in operation. The environment is being looked after, it’s being given a heighted priority and certainly for people in the Hibiscus Coast, they’ll be reassured to hear that.”
On 26 July the first section of a new outfall pipe will be towed all the way from Kaiaua (where it is being manufactured) to Army Bay. Residents along the East Coast of Auckland whose houses overlook the sea, may get a good view when the new outfall is “floated” into place, before being submerged. The second section is due to arrive on 13 August.
Once in place, the pipe will sink to the ocean floor and be secured, before being joined to the new wastewater pipe laid by Blanche. The work is part of a $31 million project to replace the treatment plant outfall pipeline and to upgrade facilities including a pump station, ultraviolet disinfection facility, electrical controls and standby generators.
The treatment plant continues to produce high quality wastewater and is capable of managing future growth from across Orewa, Silverdale and Whangapāroa. However, the outfall pipeline is nearing the end of its operational life, is currently acting as a bottle neck for treated wastewater slows and needs to be replaced with a larger pipe.
The new infrastructure will ensure greater reliability and resilience of the treatment plant as the area continues to grow. The treatment plant and discharge will continue to operate under the existing resource consent.