The latest updates and information related to the Bromley wastewater treatment fire on 1 November 2021.

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We acknowledge that you have been experiencing an unpleasant smell due to the fire at our Wastewater Treatment Plant on 1 November 2021.

We apologise for unpleasant smells from our wastewater treatment plant since the fire. We’re prioritising work that will reduce the odour and we appreciate your patience as we do everything that we can to improve the situation.

This page will be updated regularly to keep you informed of the situation and our mitigation efforts.

We will continue to monitor the quality of the wastewater discharge and improve the operation of the whole wastewater treatment process, including the oxidation ponds, to minimise the generation of odours. We have installed one aerator in Pond 1 and a further two aerators will be delivered to the site this week. Each aerator will improve the oxygen levels in the Pond and reduce the odours.

The damage assessment of the two destroyed trickling filters is still being undertaken. Until this is completed, we won’t know if it’s possible to repair the concrete housing and replace the trickling filter media. If the concrete housing is badly damaged we will look at the options for rebuilding the trickling filters alongside alternative technology.

Assessing the damage is a detailed technical process as we need to remove some of the filter media, without causing further damage to the concrete structure, and then assess the condition of that concrete structure. This is expected to be completed by the end of March 2022.

Read more on Newsline.(external link)

A plan is underway to decrease odours and improve the treatment of wastewater over the medium term at the fire-damaged Christchurch wastewater treatment plant.

After considering a range of options, Council staff plan to convert two of the plant’s four clarifier (or secondary contact) tanks into aeration tanks.

This will pump more oxygen into the wastewater earlier in the process, which we expect will help decrease the unpleasant smells and improve the quality of the wastewater before it enters the ponds.

Read more on Newsline(external link).

We're considering the next steps in the damage assessment work after completing a trial to remove a section of the fire-damaged filter media from the plant late last week. 

An excavator removed 2.2 tonnes of melted material from one of the trickling filters that were destroyed in the fire on 1 November.

You can read more on Newsline(external link)

Filter media removed from the trickling filter during the trial

The 1 November fire at the Christchurch Wastewater Treatment Plant was one of the biggest in the city for several years and its impacts could be felt for a long time.

We've answered some of your questions about our progress, how the plant is now operating, and the next steps. You can read more on Newsline.(external link) 

We've also installed the first aerator on the oxidation pond as a trial to see if the oxygen that it pumps through the water can help decrease the odour levels.

We're monitoring the results closely. If the trial is successful we plan to place more aerators in the first oxidation pond and stop treating the water with hydrogen peroxide - a compound that naturally breaks down into water and oxygen - before it's discharged into the ponds.

  • The fire that destroyed the two trickling filters has been extinguished. This was confirmed by the fire service on Thursday 25 November. 
  • While we’re doing everything we can to reduce the odours arising from the plant, unfortunately, odours will remain an issue for some time.
  • To help suppress the smells, we’ll continue to use water misters. We are also adding poly aluminium chloride – an odourless powder that dissolves in water –at two key points in the process.
  • This ‘poly dosing’ settles more of the suspended solids in the wastewater, improving the water quality as it progresses through the plant.
  • The first of a number of aerators were installed in the oxidation ponds on Friday 26 November. 
  • It’s hoped that these aerators will replace the need to add hydrogen peroxide – a compound that naturally breaks down into water and oxygen – to the wastewater before it’s discharged into the oxidation ponds.
  • Some fire-affected biosolids (a by-product of wastewater treatment) have been diverted to landfill due to traces of plastic and fibreglass being present.
  • The cause of the fire is still under investigation.
  • We’ll provide further updates on Newsline(external link)(external link) and on this page regularly over the coming weeks.
  • If you have any feedback or concerns about the odour, call us on 0800 800 169 or email us..(external link)(external link)