Friday 17 July 

Christchurch Wastewater Treatment Plant update

The final stone columns are being installed 

It's a week of milestones on site with the last stone columns going in and a concrete pour. 

Stone column installation continues today and we expect the final columns to be in place by tomorrow. Those near the site will see our contractors doing some final testing today, which they'll complete on Monday.

This will conclude the ground improvement stage of the project – a big achievement for our team shown below.

Thank you to residents and particularly neighbours of the plant all for your patience and understanding during this work. We're looking forward to moving to the next stage of the project and keeping our momentum. 

Concrete pour successful 

From the early hours of this morning we had a crew hard at work on site doing a concrete pour for the project. Around 20 truckloads (approx. 140m³) of concrete were poured, completing a section of the plant's pipework. 

Pond health, odour and what to expect this weekend 

Overall, monitoring continues to show that the oxidation ponds are in good health. Dissolved oxygen levels remain significantly higher in Ponds 2A and 2B following the installation of the new aerators.

These improvements are also continuing downstream, with elevated dissolved oxygen levels being recorded in Ponds 3, 4, 5 and 6.

We're continuing to optimise the flow split between the ponds, with a further adjustment made on Wednesday. As water typically remains within each pond for between one and five days, it can take several days before the full effects of any operational changes become apparent in the monitoring data.

Our monitoring is also demonstrating the natural biological variation that occurs within a pond treatment system as it responds to operational changes. For example, Pond 4 has shown a rapid and significant improvement, while Pond 5 has seen one of the measures we monitor decline slightly while others have improved. Overall, we're satisfied with the health and performance of the pond system.

Algae levels also remain higher than would typically be expected for this time of year and do not appear to have been adversely affected by last week's cold and wet weather.

The diesel-powered aerators operating in Ponds 2A and 2B have experienced occasional intermittent outages, which is not unexpected for a temporary installation.

These outages are being identified quickly through monitoring and responded to promptly to restore operation. Once the aerators are connected to permanent electrical power, reliability will improve further.

We don't expecte any negative impacts on pond health or odour as a result of these temporary interruptions.

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.