From Watercare media release:

Our Central Interceptor project has passed an historic milestone with the southern half of the 16.2kilometre tunnel (Blockhouse Bay south to Mngere Wastewater Treatment Plant) going live. We are now one step closer to the goal of cleaner waterways and beaches for central Auckland.

A formal event was held today (14 February) at a new pump station in Mngere, attended by Minister for Local Government Simon Watts, Auckland Mayor Wayne Brown, politicians and project teams. Around 200 guests lined the pump station shaft as Mayor Brown gave an order to start up giant pumps sending wastewater flows from the Central Interceptor tunnel to the nearby treatment plant at a rate of 1,200 litres per second.

It was an historic moment during proceedings dedicated to recognizing the accomplishments of the 600-strong Watercare and Ghella Abergeldie JV Central Interceptor project team which began construction in 2019.

Mayor Brown said that as an engineer himself, he appreciated the skills involved to achieve this outcome: Its a significant milestone for Aucklanders and a huge engineering feat for the team who have been working for the past six years. I look forward to the Central Interceptor project being completed next year to fully realise the benefit, including an 80 percent reduction in wet weather overflows and improved water quality.

This is an important piece in fixing Aucklands infrastructure. The Central Interceptor will take pressure off other parts of the network and will allow other long awaited wastewater projects to progress says Mayor Brown.

Chief programme delivery officer Shayne Cunis says getting the southern half of the Central Interceptor tunnel up and running as quickly as possible was always the goal: This is a huge result. It is rare both globally and in New Zealand for major infrastructure projects to be delivered safely, economically and on time.

We are hugely proud of the tenacity and dedication of our team in particular our construction partners Ghella Abergeldie JV. We didnt want to wait until the project was finished at the end of 2026 before getting the southern tunnel going. Weve done that despite everything thats been thrown against us, including the COVID-19 pandemic, major storm events and unprecedented inflation for modern times.

The main environmental benefits (cleaner waterways) wont however be realised until the remaining Central Interceptor tunnel (running from Mount Roskill to Herne Bay) is completed, along with new infrastructure such as the Herne Bay Collector, which is currently under design.

Its northern central city suburbs such as Mount Albert, Grey Lynn and Herne Bay where major wet weather overflows occur into the likes of Oakley Creek, Meola Stream, Point Chevalier and Point Erin beaches.

The switch on of the southern tunnel does however mean improved resilience for our wastewater network, says Shayne Cunis: Aging infrastructure such as Pump Station 23, Hillsborough was often overwhelmed by stormwater in big storms. Now the new Central Interceptor tunnel will capture these flows.

The Western Interceptor will also no longer carry flows under the Manukau Harbour, which is another win, he says.

The Central Interceptor project forms part of our $13.2b programme to deliver new water wastewater and infrastructure over the next 10 years to allow for future growth and a cleaner environment.

source: Watercare.