Watercare frees up $7 million as major Northern Interceptor milestone completed

Watercare has freed up $7 million for other priority infrastructure projects after completing one of the largest concrete pours for the Northern Interceptor – a key project that will support housing growth, strengthen network resilience, and redirect flows to areas with available capacity.

Once the Northern Interceptor comes online in October, the chamber will redirect wastewater from Hobsonville to the Rosedale Wastewater Treatment Plant.

Programme director Rob Burchell says progress has been better than expected, reducing the cost of the connection from $25 million to $18 million.

“This has been driven by strong planning, design improvements, and proactive project management.

“Delivering key components on time and under budget means we can reallocate $7 million to other projects in our $13.8 billion 10-year Business Plan (2025 - 2034)."

Photo: 57,000 litres of concrete poured to lock in the walls of the confluence chamber

Head of wastewater Andrew Deutschle says the connection will play a major role in improving network performance as Auckland grows.

“Redirecting flows to Rosedale makes better use of the treatment capacity in the north.

“Over the next decade, flows from around 160,000 households will gradually shift from Māngere to Rosedale, reducing pressure in the south and improving performance across the city.”

Project manager Paula Steinmetz says building the confluence chamber was one of the most technically challenging parts of the work.

"More than 50,000  litres of concrete have been poured to form the walls of a new confluence chamber.

“The crew spent six hours completing the pour using a 47 metre boom pump and specialist equipment to compact concrete around tight pipe penetrations.

Photo: Cementing in the walls of the confluence chamber was one of the most challenging parts of the connection works.

“The most complex area was around the Wairau Branch Sewer, which sits just 150 mm above the base slab.

“Despite the difficulty, our construction partner SEIPP Construction completed the work with minimal rework needed.

“With the chamber walls finished, crews will now install a central column, two internal walls, precast roof beams, and then lay the Northern Interceptor pipework within the chamber.”