Friday 28 August

Christchurch Wastewater Treatment Plant update

Healthy ponds 

The ponds continue to perform well, with monitoring showing positive results. This is especially encouraging as we start the seasonal transition from winter into the warmer months. All ponds remain green on our performance tracker.

One of the aerators on Pond 1 is still experiencing issues, and the contractor is continuing work to resolve it. The remaining 15 aerators are performing well and helping to support pond health and odour management. Work is also progressing on the new aerators for Ponds 2A and 2B. 

Community meeting now planned for October 

In a recent update, we mentioned we were planning a community meeting in September. We've since decided to change the timing of this meeting to late October so we can provide a more comprehensive update on several key projects and activities.

This will include the latest information on the clarifier project, how the new aerators are performing, progress on construction at the activated sludge plant site, preparations for the upcoming midge season and forecast El Niño conditions. We look forward to sharing these updates and answering any questions from the community.

The latest on construction  

Work has continued on installing the load transfer platform and completing pipework around the new reactor site. The team has also started preparing for upcoming foundation works, including establishing a new construction access point and backfilling around completed pipe sections.

Next month will be a big one for the project, with several large concrete pours planned for the reactor floor slab. Around 2250m³ of concrete will be poured, requiring approximately 318 concrete truck deliveries. We'll be contacting neighbours directly to provide information about these works and what they can expect.

From next week, work will also begin to refurbish one of the site's existing odour beds (shown at the bottom left of the aerial photo below). As part of this process, a smoke test will be carried out, so you may notice smoke rising from the beds for a short period. The odour beds will also need to be temporarily isolated for several hours, which could result in a slight increase in odour from the treatment plant site. We do not expect this to be significant and will be monitoring conditions throughout the work.

Earth bund project underway 

Preparatory works are now in their final stages ahead of the extension of the earth bund along the Shortland Street boundary of the plant site. The team is working to have everything in place before a contractor begins construction in September. Check out the before and after photos below to see what we've achieved so far. 

The earth bund is being extended to provide a visual barrier between neighbouring residents and the treatment plant. Once construction is complete, the area will be planted with native species to create an attractive landscaped buffer.

We'll continue to share updates as plans are finalised. Before work begins, we'll also be delivering information directly to Shortland Street neighbours with more details about the project and what to expect during construction.

Chemical trial outcome

Following the period of extended odour earlier this year we were approached by three companies with products intended to help reduce odour.

We carried out a trial to test the effectiveness of each product in mitigating odour and the potential impact of each product on the wastewater treatment process.

The results

The trial concluded that none of the three products trialled are suitable for operational use at plant.

The trial found:

• No strong or consistent evidence that any of products reduced odour effectively.

• Some of the observed effects could create additional treatment challenges or regulatory compliance risks.

Based on these findings, we will not be progressing with any of the products trialled.

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.