Christchurch Wastewater Treatment Plant update

Tuesday 21 April 

Construction milestones

A lot of progress is happening on site with construction of the activated sludge reactor reaching an important milestone this week.

Foundation works get underway

On Monday, our construction crews started installing the stone columns which will form the foundations for the new plant. Work is off to a great start with 10 columns installed on the first day.

This process strengthens the ground so it can support the new plant. This phase of the project is expected to take around four months.

Some vibrations will be noticeable while the work is underway. We have sensors in place across the site, and our team is monitoring them closely to ensure levels remain safely within approved limits.

Work hours are Monday to Saturday, 7.30am to 6pm.

Pipes arrive on site 

Another exciting milestone is the arrival of large discharge pipes that will connected the activated sludge plant to the clarifiers (shown below).

Once the new plant is constructed the discharge pipe will be an important part of the treatment process, taking wastewater from the treatment plant to the clarifiers where solid contaminants are separated from water.

Once complete, this facility will provide a long‑term fix to odour impacts that the community has experienced since the fire damaged the original plant in 2021.

Pond health and odour 

The ponds continue their transition into winter mode. Monitoring shows that intermittent odour is occurring and may continue during this seasonal change.

This is expected, as the ponds temporarily destabilise as the temperature drops before restabilising into winter mode. We can see that algae levels have dropped, which is a normal part of this process. 

To manage this transition, we're currently reviewing the flow of wastewater through the pond system and are considering directing more flow to Pond 4 to ease the load on Pond 1. This proactive approach helps support pond stability and manage odour as conditions change.

There are no changes to the odour status map at this stage.

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 

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.