By Ashley Karen
Tunneling in New Zealand’s Watercare Central Interceptor project has achieved the halfway milestone.
The project is the most extensive wastewater infrastructure undertaking in New Zealand’s history. The Central Interceptor will keep 226,000m3 of wastewater, control the flows into treatment plants, and decrease the number of wastewater overflows into Auckland’s waterways and Waitemata Harbor.
The 14.7km tunnel will operate from the Mangere Wastewater Treatment Plant to Grey Lynn and will be crossed by two connection sewers.
It has included boring a 1500m tunnel beneath Manukau Harbor in 11 weeks – the first time tunneling has been done underneath a significant New Zealand harbor.
Ghella Abergeldie Joint Venture is providing the NZ$1.2bn (US$710m) project, employing a 5.4m diameter Herrenknecht tunnel boring machine named Hiwa-i-te-Rangi.
Central Interceptor executive program director Shayne Cunis expressed the halfway mark had been reached despite considerable challenges.
“We all deserve to savor this moment. We’re on track to deliver this project in 2026 as planned, despite everything that has been thrown at us – Covid-19 lockdowns, closed borders, global shipping delays and major weather events. But most importantly, the project is being delivered safely,” said Cunis.
He added: “I want to pay tribute to our Ghella Abergeldie JV construction partners, as well staff from Jacobs, Aecom, Delve Underground, Watercare and our sub-contractors, who are all working so hard to deliver this project in the best way we can. This is our busiest year, with around 600 staff working on 16 sites.”
Francesco Saibene, Ghella Abergeldie Joint Venture project director, stated the Central Interceptor would be the longest excavated tunnel in New Zealand, and achieving the halfway mark was a moment to celebrate.
The first link sewer was completed in March, and construction has begun on a second link sewer, which will be finished in two drives.
Section one of the primary tunnel and both link sewers are said to be commissioned by mid-2024.
