Christchurch Wastewater Treatment Plant update

Thursday 29 January 

What we're doing to monitor and respond to odour 

We know the increase in odour is unpleasant and our teams are working hard to manage the situation. There hasn't been a significant change in the situation since yesterday and we're expecting odour will continue for at least the next week. 

Our operations team is actively tracking odour at multiple points across the plant and surrounding community, using our odour monitoring tools. Staff are reviewing results in real time and making adjustments where possible to minimise impacts.

Here are some of they key actions we're taking: 

Temporary Activated Sludge Plant 

• Our temporary activated sludge system is performing as well as it can under current conditions and and we've maintained treatment capacity. 

Pond flow adjustments 

• We’re adjusting flow through the oxidation ponds to reduce load and pressure on the section struggling most with odour.
• Pond water levels will be temporarily lowered to allow more effective flushing and to help refresh the system.

Oxygenation 

• Regular monitoring of dissolved oxygen levels continues.
• We'll deploy a jet boat to introduce additional oxygen into the ponds where it can be effective; this will be carefully balanced to avoid inadvertently stirring up settled sludge.

Aerator maintenance and upgrades 

• One of the 17 aerators on Pond 1 failed during routine electrical maintenance. Our contractor is working hard to get it returned to service as quickly as possible.
• The two newer aerators installed on Pond 2 in recent months are performing well.
• An additional aerator is scheduled to be installed in February to further support pond health.

If you’re concerned about the impacts of the odour there is a range of information on our website about odour and health, and what support is available for impacted residents.

Activated Sludge Reactor construction gets underway 

Work on site is progressing well. Our contractors HEB Construction have set up their construction village and staff are settling in on site. They've begun early site investigations, which will allow bulk earthworks to start in the first week of February. During this stage, you can expect to see up to 30 truck movements per day as material is removed and gravel is brought in.

Once the team has excavated down to about two metres, they will begin installing the stone columns that help stabilise the ground. This part of the job will take a few months. After that, they’ll build the load transfer platform, which brings the ground level back up and prepares the area for construction of the plant. This phase is expected to take around six months, depending on weather and any challenges that come up.

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.