They were advised ageing assets required replacement, improved operational efficiency and resilience would be beneficial, and growth had to be accounted for.
Mindful of calls to keep spending levels realistic, the Dunedin City Council indicated it would prioritise rehabilitation of assets over full replacement where this was possible.
By the time the council adopts its 2025-34 long-term plan this year, an infrastructure plan covering at least 30 years will sit behind it in guidance.
A council workshop in November last year provided indications of the scale of looming challenges and the broad plan for managing them.
For water supplies, 29% of the council’s assets were rated poor to very poor and about 12% were assessed as being at or beyond their theoretical useful life. Pipes were breaking more frequently.
For wastewater, 26% of assets were rated poor to very poor and about 22% were at or beyond their theoretical useful life. The network performed poorly in wet weather.
For stormwater, 39% of assets were rated poor to very poor and about 13% were at or beyond their theoretical useful life.
Planned or likely action included decommissioning the Mosgiel wastewater treatment plant, upgrading the Green Island plant and installing a new pump station and tunnel to convey wastewater from Musselburgh to Tahuna.
Improving the performance of the wastewater network in wet weather out to 2034 could come with a price tag of more than $78 million.
New wastewater treatment facilities to service Waikouaiti and Warrington, and potentially capacity for Waitati and Seacliff, and an upgrade at Middlemarch might collectively cost $75m out to 2034.
Boosting water efficiency through means such as better targeting of leaks and improved pressure management could have a price tag exceeding $82m.
Not all such spending would be regarded as new capital, because some would be considered renewal of assets.
Other plans referred to in the workshop included upgrades to Mosgiel’s stormwater networks and implementation of a climate adaptation plan in South Dunedin.
The council signalled it would soon need to take steps to ensure Dunedin had enough drinking water in the decades ahead.
Almost $260m of new capital was signalled for 2035-2055 for activities such as new alternative water sources and additional water storage.
Overall, the council signalled dealing with wastewater issues was a pressing issue for the next decade and water supplies would need considerable attention in the five years after that.
A 30-year draft budget summary for Three Waters renewal, new capital and growth indicated $514.2m for 2025-2029, $730.2m for 2030-34 and $769.6m for 2035-39.
