Onsite monitoring at the Christchurch Wastewater Treatment Plant shows an increase in odour in recent days. This is backed up by our monitoring stations beyond the site boundary.  

An investigation has identified the odour as coming from the primary settlement tanks, which process wastewater before it enters the temporary activated sludge treatment plant. Our staff are currently in the process of making changes to reduce the odour from these tanks. This is likely to take a couple of days to resolve. We’ve also engaged a consultant who specialises in odour monitoring to assist staff in identifying and responding to odour sources.

There is better news from the oxidation ponds. Our monitoring shows the ponds’ recovery over the holiday period has been maintained, with the majority of the ponds green, and only two still set at their orange setting on the tracker. There are currently 13 of 16 aerators operational, while our contractor works on repairing and returning the other three aerators to service as soon as possible.

We appreciate some of this information is disappointing, and our staff are doing all they can to reduce the odour as quickly as possible.

Hydrogen sulphide monitor results

The graph for this week shows that H2S is being detected in the Shortland Street area, and this occurs at times when the wind is coming from the treatment plant itself rather than the direction of the ponds. Our staff are doing all they can to reduce the odour as quickly as possible and are making changes to processes.

The H2S detected at the Dog Shelter is likely to be coming from either Pond 1 or 4. Detections at the South New Brighton School may be from sea lettuce in the estuary. We will  carry out additional monitoring in this area to investigate this.

Where to get help

If you need health support, we have information available on our website. This includes information on Pegasus Health's Partnership Community Workers and contact numbers for Healthline and counselling services.

Stay updated

We want everyone to be able to stay updated on our response and recovery from the treatment plant fire, and we regularly post new information and reports on ccc.govt.nz/wastewaterfire 

You're welcome to send this update to your networks. If you know someone in the community who doesn’t have email or internet access, please print this newsletter off and pass it to them.

If you know of anyone who would like to receive this e-newsletter they can subscribe online. 

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.