The new outfall pipeline – part of a NZ$31 million (AU$29.1 million) upgrade project by utility Watercare – is designed to replace an ageing 2.8 km outfall pipeline that is not equipped to cope with predicted population growth.
The NZ$6.2 million (AU$5.8 million) Herrenknecht MTBM, which has been named Blanche, will install a 2 km pipeline from the Army Bay Wastewater Treatment Plant to the foreshore using direct pipe installation to thrust sections of steel pipe into place along the route.
A further 900 m of high-density polyethylene (HDPE) pipe with concrete footings will be floated into place and installed along the seabed.
“This is the first time that this direct pipe method is being used in New Zealand and a 2 km thrust will be a world record,” said Watercare Project Manager Dirk du Plessis.
“There are many advantages to using this type of construction, which is safer for workers, produces less dust and has less impact on the environment than open-cut methods — which is particularly important as the site lies within the Shakespear wildlife sanctuary.”
The new larger pipeline will increase current wastewater discharge volume of 350 L/s to 1,400 L/s, ensuring a reliable and resilient service from the plant to the Whangapararoa region as it expands.
For more information visit the Watercare website.
If you have a project you would like featured in Trenchless Australasia contact Journalist Chloe Jenkins at cjenkins@gs-press.com.au
Images supplied by Watercare