Thursday 28 May

Christchurch Wastewater Treatment Plant update

Timeline for aerator installation 

We’re making good progress on works to get aerators installed across the ponds, with delivery taking place in two clear stages designed to achieve early improvements while longer-term infrastructure is completed.

Stage 1: powerful aerators running on diesel generators

Our immediate priority has been to get the most powerful aerators up and running as quickly as possible. These units will deliver the majority of the benefit – around 80% of the total aeration capacity.

• Aerator components were delivered to site in April and May.
• Anchor point construction for the vertical aerators ran from 18 May to 5 June.
• Installation of eight vertical aerators in the ponds is scheduled for 2–12 June.
• Commissioning the aerators and getting them running is scheduled for 15–19 June.

Once this stage is complete, the aerators will already be providing a significant uplift in pond performance while we continue with the next phase.

Stage 2: permanent electrical connections in place

The second stage focuses on transitioning all aerators to permanent electricity supply. This involves more complex work – particularly cabling across the site – which is why it takes longer. 

Key milestones include:

• Continued anchor point installation.
• Trenching and electrical cabling: 18 May – 19 August.
• Main container and switchboard installation: 22 July – 30 August.
• Commissioning of permanent power beginning 19 August, with completion anticipated late August. 

What this means

By mid June, the ponds will already benefit from the majority of aeration capacity via diesel-powered units. The transition to permanent electricity later in August will complete the project, ensuring full efficiency and long-term reliability.

Construction update: activated sludge reactor

Construction of the activated sludge plant continues to progress well, with approximately 800 stone columns installed, bringing this phase of the project close to the halfway point. 

Another key milestone has also been achieved with the installation of the PE pipes now underway (shown below), marking a significant step forward in the build. Work will continue at pace as the project moves into the next stage.

Pond health, odour and what to expect this weekend

Conditions across the ponds remain steady as we move further into the cooler months. The system is continuing to adjust to seasonal changes, with performance remaining consistent overall. Algae levels are still sitting slightly above typical winter expectations, and the team is maintaining close oversight to ensure any changes are managed early.

What to expect this weekend 

Conditions are forecast to remain relatively settled over the weekend, and no significant odour increases are expected. As the seasonal transition continues, there remains a possibility of occasional short-term odour spikes, but nothing out of the ordinary is anticipated over the next few days.

Looking ahead to next week

We are keeping a close eye on a potential weather system moving through from mid next week, which could influence pond conditions. We will continue to monitor this closely and provide a further update in next week’s newsletter.

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.