Water  |  Yesterday

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To mitigate the ongoing stench coming from its Wastewater Treatment Plant, Christchurch City Council is investigating pumping a portion of treated wastewater straight to the existing ocean outfall pipe.

Cooler temperatures and high levels of rain have reduced the oxygen and algae levels in the ponds, which has caused the current spikes in odour.

Mayor Phil Mauger says the Council has been in discussions with Environment Canterbury and mana whenua about finding an interim solution.

“Because the Wastewater Treatment Plant has been running on a knife edge since the fire, the ponds have been overloaded and are now in poor health,” Mayor Phil Mauger says.

“We can’t sit back and expect conditions to improve on their own.”

“Anyone who lives nearby knows the odour issues have become more intense, and we’ve been looking at all ways to help alleviate the stench.”

“Reducing the amount of wastewater entering the ponds will take the load off, give them space to recover, and – most importantly – address the current odour,” he said.

“If we can reduce how much wastewater is going into them, it will help stabilise pond conditions while the longer-term rebuild of our new treatment plant continues.”

This approach would also provide extra resilience across the treatment system through construction of the new activated sludge reactor and essential maintenance on one of the plant’s clarifiers.

The wastewater diverted to the outfall would be partially treated, and the Council would add chlorine to ensure bacteria levels are safe before it reaches the ocean.

There are a number of elements to work through to get this up and running. Staff are developing a plan as quickly as possible and will keep residents updated as this plan progresses.  

Mayor Mauger said the Council will continue to look at further actions to improve pond health and reduce odour.