Fresh from delivering Auckland’s Central Interceptor, Ghella has signed the contract for a new wastewater pipeline in the New Zealand city.
Ghella will deliver the Herne Bay Collector – a 1.7km-long, 2.1m-diameter wastewater tunnel in Herne Bay that will connect into the Central Interceptor[https://www.tunnelsandtunnelling.com/news/tbm-makes-final-breakthrough-on-nzs-central-interceptor/] and reduce wet weather overflows into the Waitematā Harbour.
The scope includes seven main shafts, three intermediate shafts, overflow connections to existing engineered overflow points, and a control chamber at Pt Erin Park. The chamber will connect the Herne Bay Collector into the Central Interceptor system, forming part of Auckland’s wider wastewater network.
The project will use the micro TBM previously deployed on the Central Interceptor link sewers. A large proportion of the original mTBM tunnelling team is now working on Herne Bay, with additional personnel transferring across from the Central Interceptor.
Since last year, Ghella has been progressing detailed design following service location investigations. This year, focus has shifted to service relocations and enabling works under separate early works contracts, preparing the corridor for main construction activities.
The project is particularly complex because of the urban setting in a densely populated and established waterfront suburb. With very few cross streets, challenging topography, and properties located just metres from the works, Ghella said careful planning and co-ordination was essential throughout delivery. The pipeline will be constructed beneath local streets at depths of 9-22m.
The Herne Bay Collector is part of a wider programme of work building on the Central Interceptor, a 16.2km wastewater tunnel running from Herne Bay to Māngere.
The southern half of the tunnel has been live since early 2025 and the northern half is due to go live in mid-2026, making the tunnel fully operational.
The NZ$260m (€132m) Herne Bay Collector will capture wet weather overflows from some of Auckland’s oldest combined wastewater and stormwater networks and direct them into the Central Interceptor for treatment at the Māngere Wastewater Treatment Plant.
Watercare chief programme delivery officer Mark Crowle said the project was part of one of the most significant upgrades to wastewater infrastructure in Auckland’s history.
“Over the next 10 years, Watercare will invest approximately NZ$13.8bn (€7m) to improve the region’s drinking water and wastewater infrastructure,” he said.
Ghella country director for New Zealand Rosario Barresi said the company was proud to continue its journey with Watercare through the Herne Bay project, building on the strong relationship established during the Central Interceptor
“This contract reflects the trust built over time and a shared ambition to deliver meaningful outcomes for Auckland,” he said.
“Together, we are contributing to the protection of Auckland’s coastal waters and helping to improve its beaches and surrounding areas for future generations.
Construction is under way and the project is expected to be finished in late 2028.
