Aerators up and running mid-June
Thursday 14 May
Christchurch Wastewater Treatment Plant update
Aerators up and running mid-June
Last week we shared that we expected the first aerators to be operational within six to eight weeks. Since then, we’ve made good progress finalising key pieces of the puzzle for installation.
We can now confirm that we're aiming to have at least four higher‑kilowatt aerators – which provide a lot of the oxygen to the ponds – up and running by mid‑June, powered by generators. Getting these larger units operational first will significantly improve aeration levels in the ponds, so we’re pleased to prioritise this step.
This is a couple of weeks later than initially estimated, largely due to the time required to engage the main contractor and begin enabling works.
The timeline for the permanent power supply which will enable all the aerators to be deployed in the ponds has also shifted slightly and is now expected to be fully operational by late August. This is due to supply chain challenges.
Chemical supplier trial
We have a second trial underway to assess whether products from three additional suppliers could help reduce the risk of odour from the oxidation ponds.
Last year, we undertook an initial trial involving products from six suppliers, with four progressing through to detailed testing. While some products showed potential benefits, they did not achieve the desired results under the specific conditions found in our ponds.
This latest trial will assess three further products over three separate fortnight-long testing periods. The first trial period began on Tuesday.
The testing process involves applying each product to a 1000-litre sample of oxidation pond influent (in the bins above) and monitoring the effects on a range of water and air quality indicators. When then compare the results from each treated sample against a control sample with no product added.
Construction update
Over the next couple of weeks, installation of the stone columns may slow slightly while we carry out testing as part of our quality plan for the project. Once complete, installation will ramp back up, and we remain on track at this stage of the project.
To date, 550 of 1600 stone columns have been installed. The green dots on the map show which stone columns have been installed (as at 13 May).
Another milestone has been reached this week, with test welds underway for the pipelines that move wastewater through the different parts of the treatment process (pictured below). Installation in the ground is scheduled to begin next week.
A word from Gary
I’ve been out and about in the neighbourhood again this week and have been making more positive connections in the community. In particular I’ve been connecting with neighbours living close to the plant. It’s always valuable to hear directly from the community and talk through what’s happening on site.
As part of my work to meet people in the area I’ll be attending the community BBQ for the Bromley streets consultation currently underway.
Date: Sunday 17 May 2026
Time: Noon to 2pm
Location: Bayswater Reserve
Come along for a free sausage sizzle and a chat.
Pond health, odour and what to expect this weekend
There have been occasional spikes in odour over the past week, due to the ponds continuing their seasonal transition into winter conditions.
Monitoring of pond conditions shows dissolved oxygen levels have reduced, indicating algae levels have dropped as expected through the summer-to-winter transition. Cooler water temperatures are also slowing biological activity within the ponds, which reduces overall oxygen demand.
Overall, pond conditions are stable, and pond health is considered to be as good as can reasonably be expected at this time of year.
The weather forecast for this weekend remains relatively settled, with cooler days and nights expected. We currently don't expect any significant changes in odour levels.
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.
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