We’re one week into an intensive odour monitoring programme focused on the Christchurch Wastewater Treatment Plant itself rather than the oxidation ponds. This will help us better determine the source of recent odour from the plant. This monitoring programme will continue for another three to four weeks.

The initial results from the odour survey show odour is due to the underperformance of the primary settlement tanks. We’re working to address this issue by optimising the performance of the tanks, which should reduce odour from this source.

In terms of the oxidation ponds, we are detecting intermittent odour from Oxidation Pond #1. We’re continuing work with the contractor to get all the pond aerators back into service. Three of the eleven vertical shaft aerators are currently out of service, but one is due to be back before the end of the week. We expect all aerators should be back in service by the end of February or early next month.

At this time of year decomposing sea lettuce in the estuary can also be a source of odour, particularly in Ferrymead and coastal areas.

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 at the plant. Unfortunately the hot weather early in the week did increase the levels being recorded, and it is good to see that they are now decreasing again.

Currently there are no readings for the dog shelter as that meter is being  used at another site.

Detections at the South New Brighton School may be from sea lettuce in the estuary. We are carrying 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.