Transition to winter mode resulting in odour
Odour as ponds transition to winter mode
The recent settled weather conditions have resulted in the transition from summer to winter mode taking longer than usual. This has resulted in increased odour from the oxidation ponds.
When the transition to winter mode is complete we see the ponds turn from green to brown, algae dies, dissolved oxygen levels drop, and there is much less biological activity.
While the algae has now died off, other biological activity is continuing, which has decreased the dissolved oxygen levels in the ponds. This is the cause of current odour.
In addition to this, the settled and calm weather conditions allow the gases from the ponds to accumulate, which then disperse to neighbouring areas when the wind picks up.
Overall the wastewater treatment plant processes are continuing to operate well at full capacity.
As the transition to winter mode progresses, we expect the ponds will stabilise and odour will decrease. Intermittent odours do remain a possibility throughout the winter months, particularly in settled weather and high rainfall events.
Our team closely monitors the ponds and plant operations and makes tweaks where possible to keep odours to a minimum.
Activated Sludge Plant update
All preparatory work to make room for the new plant is complete. Initial ground-improvement and structural design work is also complete. This will be peer-reviewed and finalised ahead of the work going to tender toward the end of July.
Over the next couple of months we’ll focus on completing the electrical and mechanical design elements so the full package is ready for tender at the same time.
Stay updated
We want everyone to be able to stay updated on what's happening at the Christchurch Wastewater Treatment Plant, and we regularly post new information on ccc.govt.nz/wastewaterfire
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If you have any questions, or would like further information on the project, please call us on 03 941 8999 or 0800 800 169 or email wastewater@ccc.govt.nz
Thanks for your patience and understanding. We’ll be in touch again soon.
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