The proposal would see treated wastewater from a planned new Ruakākā wastewater treatment plant at Rama Rd near Marsden Point discharged into the ocean.
It would be New Zealand’s first new open-ocean treated wastewater outfall in more than a decade.
The ocean outfall is the first of three major Ruakākā wastewater projects expected to move into construction.
It forms part of wider plans to provide wastewater capacity for future residential and commercial growth across Bream Bay.
The ocean pipeline’s design has been undertaken by a United States-based engineering and infrastructure multinational with about 51,000 employees worldwide.
Plans including a treated sewage ocean outfall for a much-enlarged new Ruakākā wastewater treatment plant were discussed at a May WDC council briefing. Photo / Susan Botting
It specialises in major water, wastewater and environmental infrastructure projects.
Alternative wastewater disposal options are also being investigated.
A completed separate business case examining ocean outfall alternatives is also due before the Northland Waters board next month for endorsement before being considered by the council in November.
The assessment is being undertaken by a team including Canadian-based engineering multinational WSP with Auckland-based environmental consultancy Pattle Delamore Partners (PDP) and water and environmental consultancy Williamson Water & Land Advisory (WWLA).
This work is examining whether alternatives could provide a viable long-term wastewater disposal solution for the growing Bream Bay area.
It is scheduled to continue through the 2029-30 financial year.
Work on a significantly larger Ruakākā wastewater treatment plant at Rama Rd near Marsden Point is also progressing.
A business case for the treatment plant has been completed and is scheduled to go before the Northland Waters board next month before heading to Whangārei District Council in November.
Construction of the upgraded treatment plant is currently programmed to begin in early 2028 and be completed by July 2031.
The treatment plant design programme has been led by PDP, which was commissioned to investigate options and develop preliminary designs.
A visual representation of the new Ruakākā wastewater treatment plant provision was shown to councillors earlier this year. Photo / Susan Botting
Meanwhile, work has also begun securing additional interim discharge capacity for the existing Ruakākā wastewater treatment plant while long-term solutions are developed.
Design work is underway at Te Poupouwhenua, where site assessments have been completed and vegetation management plans are being implemented to help determine pipeline routes and address environmental constraints.
Investigations are also underway on Land Information New Zealand-owned land, where percolation testing has been completed. Results expected next month will help determine whether rapid filtration is a viable treated wastewater disposal option.
Design work for this interim discharge project is being led by Canadian engineering and environmental consultancy Stantec, which employs about 32,000 people worldwide and specialises in water, wastewater and infrastructure projects.
The interim discharge project is scheduled for completion in April.
■ LDR is local body journalism co-funded by RNZ and NZ On Air.