Watercare’s 16.2km Central Interceptor tunnel runs from Point Erin in Herne Bay to the Māngere Wastewater Treatment Plant.
Together with its link sewers in Mt Roskill, Blockhouse Bay and Mt Albert, it captures and transfers wastewater and stormwater flows that would otherwise contribute to wet-weather overflows.
“It’s 4.5m-high, as high as a giraffe and that does create a lot of storage,” Sinclair told media.
“So we’re able to manage the wastewater network in a different way, able to store more stormwater and wastewater as it’s combined. So we should be able to manage those flows a lot better.”
Mayor Wayne Brown said it’s an example of Auckland making its own decisions and paying for them.
“It’s really important and it shows that we as a city can maturely make decisions and pay for things and do it ourselves, and that’s what we’ve done in this one,” Brown said.
“This is not a government project. This is a council and city project. And I think that Watercare have done a very good job of that and we should be thankful for them.”
The southern half of the tunnel went live early last year, with Watercare estimating it’s already prevented 741,000cu mof wastewater and stormwater from overflowing.
That’s the equivalent of almost 300 Olympic-sized swimming pools.
With the northern section now in service, the full tunnel is operational.
Brown says its completionis a significant achievement that will benefit Aucklanders by reducing wet-weather overflows and helping to improve the health of our harbours and local streams.
It’s hoped fewer beaches will have black flags this summer and the water will be healthier in general.
The project was delivered on time – and slightly over budget.
“We had a couple of scope additions, so it was the original central interceptor was meant to end in Mount Albert. It was extended to Grey Lynn, and then further extended to Point Erin to maximise the benefits,” Sinclair said.
“When we added up those scope extensions, the budget was $1.5 billion, and we ended up at $1.66b.”
That’s despite massive challenges including major weather events, a pandemic and inflation.
More than 4300 people have worked on the project.
So what’s next for those workers and the city?
“We definitely want an [infrastructure] pipeline because Watercare’s got a huge programme ahead of it, and we want to make sure that we’ve, you know, got the workforce available. We’re looking forward to announcing in due course those big programmes and keeping that pipeline alive so we can build that capacity into the market.
“We want to keep people employed, we want to keep the contractors in, in market and the right equipment as well.”
Katie Bradford is a Senior Correspondent at the Herald. She has been a broadcast journalist for over 20 years and was based in the press gallery for 10 years. She specialises in politics, business and Auckland issues.