Ghella has commenced tunnelling on Watercare’s Herne Bay Collector in Auckland.
Micro TBM Domenica has started excavating the first of seven sections of the tunnel that will help reduce wastewater overflows into the Waitematā Harbour.
The project includes seven main shafts, three intermediate shafts and a seven-storey underground control chamber built in the 20m-deep shaft beneath Point Erin Park.
The Herne Bay Collector is a 1.7km-long, 2.1m-diameter wastewater tunnel and is a key project in Watercare’s NZ$1.6bn (€800m) Waitematā Water Quality Improvement Programme, which will build on the benefits being delivered by the Central Interceptor.
The Waitematā Water Quality Improvement Programme is one of nine work programmes in Watercare’s NZ$15.2bn, 10-year capital investment programme, which comprises more than 1,000 projects.
Once complete, the NZ$260m Herne Bay Collector will capture wet weather flows from Herne Bay’s combined wastewater and stormwater network and divert them to the Central Interceptor for treatment at the Māngere Wastewater Treatment Plant.
The collector will have the capacity to divert 6,000 litres per second of combined and wet weather flows.
Watercare chief infrastructure officer Mark Crowle said using micro tunnelling technology helped minimise surface disruption during construction.
“The advantage of micro tunnelling is that we can carry out most of the work underground from a series of shaft sites, rather than needing to excavate a continuous trench through Herne Bay’s streets,” he said.
Ghella New Zealand country director Rosario Barresi said Domenica was expected to complete the first 626m drive around mid-next year.
“Launching Domenica is an incredibly proud moment for our team. Delivering complex underground infrastructure for Watercare and for Auckland, in such a constrained residential environment, with homes just metres from our sites, has required exceptional planning, precision and teamwork,” Barresi said.
