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The Tunnel Boring Machine called Blanche at Watercare’s Army Bay Wastewater Treatment Plant, pictured, has so far travelled 952m – almost halfway through its 2km journey from the plant to the transition point, 500m offshore.
The state of the art machine (HM April 18) only travels 28-35mm per minute, cutting through the ground and laying a new wastewater pipe.
On July 26 the first section of a new outfall pipe will be towed by sea all the way from Kaiaua, where it is being manufactured, to the Tiri Channel off Army Bay. Residents 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 August 13.
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 itself is capable of managing future growth from across Orewa, Silverdale and Whangaparoa. However, the outfall pipeline is nearing the end of its operational life, creating a bottleneck for treated wastewater – which is why it is being replaced with a larger pipe.
