Christchurch Wastewater Treatment Plant update
Wednesday 15 April
The ponds continue to be stable as we transition from summer to winter. The algae level is still good, although we expect it to decline as temperatures continue to drop.
In addition to monitoring the overall health of the ponds, the team at the plant is progressively reducing the hydrogen peroxide dosing – at this stage, it's nighttime only. They've also begun preparatory works to install the additional aerators that the Council approved a couple of weeks ago, so you may notice an increase in vehicle movements within the pond area while this is underway. We're working as quickly as possible and we're planning for the final installation, with permanent power supply, to be completed by July this year.
Last week's spike
Last Thursday and Friday, we noticed a short-term spike in H₂S levels at our monitors on Shortland Street and Carter Street. We've looked into the reasons, taking into account wind direction at the time, and it looks like we can attribute the spike to a controlled release of biogas from the digester pressure relief valves. Most likely, this is due to some enabling works for planned capital works that we undertook onsite on Wednesday.
We saw no further spikes over the weekend at either location, and digester conditions have returned to normal. We'll keep an eye on this process and update you if there are any further changes.
Construction update: Activated sludge reactor foundations
We've now completed a test installation of stone columns on the activated sludge reactor site. These stone columns will strengthen the ground beneath the reactor and surrounding infrastructure. The image on the left shows the process for each.
Preparations are now underway for the next stage of works – installing up to 1600 permanent stone columns across the site.
Work will start next week, and once underway, installation is expected to:
- Take approximately 15 weeks
- Occur during daylight hours, Monday to Saturday
- Progress at a rate of around 20 columns per day.
Some residents may notice minor ground vibrations while the columns are installed.
Monitoring equipment is in place around the site, and construction will pause if vibration levels exceed expected limits.
We appreciate the community’s patience while this important foundation work is carried out and will continue to share updates as the project progresses.
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.
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