Friday 19 June

Christchurch Wastewater Treatment Plant update

Stage one of aerator install complete 

As mentioned in Wednesday’s update, the first eight of the new aerators are now operational.

There is a possibility this work could create some short-term odour effects. However, so far we have not noticed any odour issues or seen any significant changes in our odour monitoring.

The aerators are currently operating on diesel generators while we complete electrical connections. We have been closely monitoring noise levels from the generators. We are also assessing diesel consumption rates and expect it will take approximately one week of operation to develop a clear understanding of fuel usage requirements.

These eight aerators provide around 80% of the new aeration capacity being added to the ponds, and it is great to have them operating.

In late August, we will begin commissioning the remaining 13 horizontal aerators, with full operation of all aerators expected in September. While the eight larger aerators are now commissioned, there may be occasions when some units need to be temporarily shut down to allow contractors to undertake construction work within the area.

The additional aeration capacity will support important maintenance work across the plant, including planned clarifier repairs later this year. It will also help manage periods during construction of the new activated sludge reactor, when more wastewater will need to be directed to the ponds.

Work is progressing well on the permanent power supply. So far, crews have installed 700 metres of electrical ducting, with a further 1300 metres still to be installed.

At the same time, we are making changes to the way wastewater moves through the pond system to get the most benefit from the increased aeration capacity.

Hydrogen sulphide monitors offline for two weeks from Monday

Our hydrogen sulphide monitors will be offline for routine calibration for two weeks. This planned maintenance is essential to ensure that the meters perform well and accurately.

We’ll take them down on 22 June, send them away for the calibration and return them to service when they are returned around 6 July. During this time, you won’t be able to see any data on our online hydrogen sulphide dashboard.

Our team will be out and about throughout this period keeping an eye on pond health and checking for odour. We appreciate your patience while we complete this important maintenance work.

Catch up on the community meeting

Thank you to everyone who joined us for the community meeting on Wednesday evening. Our team shared updates on current work at the plant and answered questions from the community.

If you weren’t able to attend, you can watch the presentations from the meeting on the Waitai Coastal-Burwood-Linwood Community Board YouTube channel.

Construction continues at the sludge plant 

Crews have now installed 1182 of approximately 1600 stone columns, meaning this stage of the project is 74% complete.

Once this part of the project is complete we’ll move onto the next stages, including: 

• Constructing a gravel platform for the bioreactor structure to sit on. This will require large rollers which will cause vibration. 
• Continued installation of underground pipework.
• Concrete pours, which will occasionally require early starts. We will communicate with neighbours before these activities begin.

Looking ahead

Commissioning of the new treatment plant remains scheduled for early 2028. The transition from temporary operations to the new plant will occur progressively throughout 2028.

Pond health, odour and what to expect this weekend

The ponds remain relatively healthy. The cold weather is expected to move the ponds fully into winter mode and increased flows through the ponds are likely to flush algae through the pond system.

We don't expect this to create significant odour issues because the cooler temperatures have already reduced biological activity to typical winter levels.

At this stage, we expect the seasonal transition to be completed with minimal odour impacts for the surrounding community.

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.