15 Apr 2026

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Councillors were today presented with options to help reduce the cost of the Akaroa wastewater treatment scheme.

The irrigation-to-land option previously agreed by Council in 2020 is now forecast to cost about $175 million. The project budget in the Long Term Plan 2024-2034 is $98 million. 

Council’s Head of Three Waters, Gavin Hutchison, says staff have considered a wide range of alternatives to determine whether more cost-effective options are now available. 

“Since Council made its decision in 2020, construction costs have increased significantly and the Government has introduced new wastewater legislation and standards,” Mr Hutchison says. 

“We’ve assessed more than a dozen possible wastewater discharge options. From that work, two main options, and several variations of the land based one, are being presented for Council’s consideration. The options are either modified irrigation to land options, with less storage and a possible relocation of the treatment plant, or a harbour outfall rather than irrigation to land.

“While much of the infrastructure cost is common across all options — including treatment, pumping and reticulation — the discharge method has a significant impact on the total project cost,” Mr Hutchison says.

The Government introduced legal changes in late 2025, with the Wastewater Environmental Performance Standard Regulations, changes to the Resource Management Act and the new Local Government (Water Services) Act. These changes set treatment and discharge standards for new wastewater consents and require councils to use the most cost-effective option for providing wastewater services over the lifetime of the wastewater system. 

Staff have assessed what those changes mean for both the current land-based irrigation proposal and alternative discharge methods.

The feasible cost-reduction options presented to Council today for the Council’s consideration are: 

  • Four land irrigation options: Involving higher irrigation rates, a reduced irrigation area, reduced storage, and relocating the wastewater treatment plant to the other side of Old Coach Road. Irrigation would remain in the same locations as currently proposed at Hammond Point and Robinsons Bay
Land irrigation options Robinsons Bay irrigation storage Treatment plant location Estimated capital cost
Option 1 16,000m³ Moves across the road $150 million
Option 2 4,000 m³ Moves across the road $136 million
Option 3 16,000 m³ Stays at current location $160 million
Option 4 4,000 m³ Stays at current location $146 million

 

  • Harbour outfall (Option 5): A 2.7km pipeline with treated wastewater discharged to the mid‑harbour area.
    Estimated capital cost: $127 million

The Council will consider the options to reduce costs at its meeting on Wednesday 22 April.