Deep beneath Auckland’s streets and harbour, a super-sized wastewater pipe has been taking shape, created in the wake of a massive 4.5m diameter tunnel-boring machine known as Hiwa-i-te-Rangi.
At $1.6 billion, the Central Interceptor will be one of New Zealand’s biggest budget civil construction projects and its longest bored tunnel when completed – making it arguably one of the most epic infrastructure projects in our country’s history.
Work has been underway on the 16.2km-long tunnel since 2019, with the southern section from Māngere to Mount Roskill already operating and the second and final section from Mount Roskill to Point Erin in Herne Bay due to open later this year.
Built for Watercare by Ghella Abergeldie Joint Venture (GAJV), the Central Interceptor will capture flows from Auckland’s old wastewater and stormwater system and funnel them to Māngere Wastewater Treatment Plant for processing. This will see an 80 per cent reduction in wet weather overflows into streams and will improve water quality in the Waitematā Harbour.
Satisfying work in a subterranean world: Mosè’s epic effort
GAJV Tunnel Boring Machine Erector Operator Mosè D’Arsiè says being part of such a monumental project has been transformative.
Starting on the project as a labourer gave him his first taste of civil construction and a chance to pursue a career path that was vastly different, and better paying, than anything he had experienced in his previous industry – hospitality.
“I came to New Zealand from Italy without speaking English, so what I would say is give civil construction a try because you can learn from every job and everybody on the team.”
Now Mosè operates sophisticated machinery essential to the project, putting together concrete rings that form the tunnel walls using pre-cast segments weighing more than three tonnes – a highly technical job requiring precision, skill and teamwork.
Hiwa-i-te-Rangi started tunneling along the path of the pipe in July 2021, working beneath the city and Manakau Harbour at a depth of anywhere between 15- and 110-metres, and finished its journey at the end of March. Mosè and his team travelled behind the almost 200-metre-long behemoth, constructing the rings in its wake as it advanced around 22 metres per day. Tunnelling has taken place 24-hours per day, six days per week and the concrete rings are coated with a plastic liner to protect against the corrosive effects of wastewater, ensuring the tunnel should last 100 years.
Mosè says the opportunities in such a huge project are “unbelievable” and “you don’t know until you are inside what you can achieve.”
“There are a lot of different jobs to do and different skills that we can develop. That’s what I like because now I’m doing something that is important and I know that with effort you can grow a lot.”
He says knowing the positive effect the project will have on Auckland’s environment and its communities gives him and his team a huge sense of satisfaction.
“The Central Interceptor is going to lead to cleaner beaches and waterways in Auckland. At the end of the day, you’re proud of what you’re doing.”
While roles like Mosè’s are vital to the physical construction of the tunnel, the Central Interceptor project, like all major infrastructure initiatives, provides job opportunities for people with a diverse range of professional skills beyond engineering and construction.
Keeping people safe: Annaliese’s vital role
Annaliese Coates joined GAJV to work on the project in 2019 as an office assistant, without a clear career direction. However, through exposure to different aspects of the operation, she discovered her passion for health and safety and is now a Health and Wellbeing Advisor.
Annaliese plays a crucial role in ensuring the safety and wellbeing of everyone working on the project, particularly those operating in challenging underground environments.
“We take the health, safety and wellbeing of our staff as the number one priority – it’s our main purpose.”
Every new employee undergoes a two-day mandatory safety induction course, plus a strict verification of competency procedure to keep them and worksites as safe as possible.
She says Watercare and GAJV have a shared vision of keeping all employees safe and empowering staff to ask questions and raise any potential safety concerns, without fear or embarrassment, is a hallmark of their approach.
Her work includes implementing annual health-monitoring checks, cardiovascular wellness initiatives, and injury management plans with client and Central Interceptor project owner Watercare supporting the focus on employee wellbeing. Input from Mates in Construction as well as Employee Assistance Programs help look after the mental side of employees’ health.
Annaliese says it’s been “unreal” being part of such a massive project, with the positive working environment helping her career to grow and Ghella paying for training courses to support her professional development.
“GAJV has been nothing but supportive and encourages me and other young people to try new things and get involved. When I first started, I was in administration and I had no idea what I wanted to do.”
Next steps on the project, and for Auckland
Watercare Central Interceptor Programme Director and Engineer David White says the project is a “rare beast’ because it’s being delivered safely, on time and almost to budget.
“If you look around the world, or within New Zealand, you’ll know how challenging that is to achieve.
“While the southern part of the project has been commissioned and tunnelling may be over, we’ve still got considerable work to do at our northern sites, where the tunnel is being connected to the local wastewater network.
“Some of these sites, such as the one in Wairere Avenue, Mount Albert have basalt rock, which makes any kind of excavation harder, but we’re pleased with progress.”
He says as the Central Interceptor draws to a close, Watercare’s focus is turning to other new infrastructure – much of which will provide employment opportunities.
In March, Watercare released a business plan outlining how it aims to deliver $13.8b of new projects over the next 10 years. These projects include a replacement for Huia Water Treatment Plant in the Waitākere Ranges and major upgrades to Māngere Wastewater Treatment Plant, as well as maintaining dozens of other treatment plants, pump stations and thousands of kilometres of pipes over the entire Auckland region.
“There’s never been a better time for people to enter the water industry,” David says.
The Central Interceptor project has certainly been evidence of the opportunities the civil construction can provide. Employing a team of 600 people across 17 sites at its peak, it demonstrates how infrastructure projects can provide paths to rewarding careers, even for those who never imagined themselves in the industry.
As Auckland prepares to benefit from cleaner waterways for generations to come, professionals like Mosè and Annaliese can take pride in being part of one of the most epic civil engineering achievements the country has ever seen.
