On 1 November 2021, a large fire destroyed both of the trickling filters at the Christchurch wastewater treatment plant in Bromley.
The trickling filters are a critical piece of the sewerage treatment process and the damage to them made the treatment process considerably less effective.
As a consequence, Christchurch residents, particularly those downwind during the predominantly easterly winds, have experienced a significant increase in unpleasant odours.
These smells initially came from the burnt trickling filters, but are now coming from areas of the Christchurch Wastewater Treatment Plant and oxidation ponds.
Despite our best efforts, the change to the treatment process without the trickling filters means there is an increase in solids and biological material entering the oxidation ponds, contributing to the stench.
Work to address odour
The interactive map below shows what we’ve got planned or underway to address odour at the Wastewater Treatment Plant. We’ll keep this map up-to-date as our work changes.
Select a hot spot to see a description of what work is being done to address odour at different parts of the plant.
- Green: Good treatment stage process performance, the probability of odour is low.
- Orange: Average treatment stage process performance, the probability of odour is possible.
- Red: Poor treatment stage process performance, the probability of odour is high.
1. Inlet screen room
A project is underway to install a new ventilation system which complies with the hydrogen sulphide safe working limits. It's estimated this work will be complete in early 2025.
An initial investigation report from a consultant suggests the Inlet Screen Room should now have sufficient airflow with the addition of a fan assisted cross-ventilation system.
2. Primary settlement tanks
A project is underway to improve the automatic water spray scum removal system. Our site staff are working closely with the project team to ensure successful delivery.
3. Temporary secondary treatment
We carried out a review the operating parameters of the temporary activated sludge plant.
We've completed all phases of a trial and are awaiting the data assessment. In the meantime, site staff are actively managing the treatment stage to effectively handle the industrial Christmas load.
4. Oxidation ponds
The oxidation ponds have now transitioned into summer mode, and our site staff are actively monitoring them to ensure optimal performance.
Site staff are working closely with our contractor to ensure the aerators remain fully operational.
5. Digesters
A project is planned to upsize the pipework, aiming to reduce the emergency release of biogas.
6. Sludge dryer
A project is underway to do an extensive maintenance overhaul of the sludge dryer to reduce wet biosolid accumulation on site. Our site staff are working closely with the project team to ensure successful delivery.
Wind trends in Bromley
Information about wind directions in Bromley and how they differ over the seasons.