Thursday 20 August

Christchurch Wastewater Treatment Plant update

Ponds go green! 

We're pleased to report continued positive progress in the health of our oxidation ponds. 

Ongoing pond monitoring continues to show strong health indicators, with results reaching levels not seen since before the fire. This is a very encouraging sign and reflects the improving condition of the pond system.

As a result of the improved pond health and consistently good monitoring results, Pond 1 has been moved to green on the pond odour tracker. This is the first time all ponds have been green since we implemented this tracker following the odour event earlier this year. 

We are also observing an increase in algae growth, which is slightly unusual for this time of year. While elevated algae levels are not currently a cause for concern, staff will continue to monitor the trend closely. Algae forms part of the food source for midges, and recent aerator servicing has identified the presence of bloodworms in the ponds, which are a natural stage in the midge lifecycle. In response, staff have commenced seasonal midge monitoring earlier than usual.

Aerator #5 on Pond 1 is now back in operation following an extended outage. After investigating the issue, the contractor identified a faulty cable and has implemented a repair. Staff and the contractor will continue to closely monitor the aerator's performance to ensure it remains operating as expected.

As part of planned maintenance, Pond 1's aerators will be briefly switched off this Saturday to enable connection works. This essential shutdown is not expected to affect treatment capacity or increase the risk of odour.

Aerators on track 

Progress on the pond aerator installation continues, with the remaining aerators expected to be in place on the ponds by 4 September.

Work on the permanent power supply is also progressing well. The remaining cabling, switchboard installation, and connection to mains power are all on track to be completed during August.

With all the work on track we're expecting to switch to having all aerators operational on electrical power on 10 September completing this project.

The latest on construction  

Construction of the activated sludge reactor continues to progress well, with the team currently focused on completing the installation of key pipework, including the dosing manhole on the southern side of the site.

Installation of the load transfer platform is also continuing, with the first section expected to be completed next week.

We're planning for the first concrete pour for the new plant next week. This concrete will provide the working platform required for the installation of steel reinforcement and formwork for the reactor's floor slab.

The reactor floor slab will be constructed in 10 stages, with works commencing in the south-western section (shown in purple below) before progressing through the remaining pours. This staged approach helps ensure quality control and efficient delivery of the structure. We'll keep youn updated on concrete pour progress via this 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 cwtp@ccc.govt.nz  

Thanks for your patience and understanding. We’ll be in touch again soon.