The wellbeing of our residents is our top priority and we continue to focus on work that will improve the quality of life for everyone who has been living with a horrible odour since the fire on 1 November 2021.

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We’re working as fast as we can to implement new methods for treating wastewater and have appointed contractors to remove the rotting material from inside the treatment plant.

Our contractors have developed an accelerated programme that sees them working six days a week, 12 hours per day. At this pace, we hope to see all of the material removed from the trickling filters by spring 2022.

We have developed an updates page on Newsline(external link) where we'll regularly provide new information as it comes to hand. Check it out for the latest news.

We know that many of you have been living with a stench since the fire on 1 November 2021.

We apologise for the horrible smells from our wastewater treatment plant. We continue to prioritise work that will reduce the odour and we appreciate your patience as we do everything we can to improve the situation.

Below you can find an overview of the project, timeline, frequently asked questions and past newsletters. This page will be updated regularly to keep you informed.

17 June 2022

Work to remove material from the fire-damaged trickling filters at the Christchurch Wastewater Treatment Plant has gained momentum over the past week, with our contractor, Southern Demolition and Salvage, extracting an estimated 30 per cent of the filter media (about 316 tonnes) so far.

Sheet-piling of the ramp to the second trickling filter has also continued over the past seven days and is expected to be completed by the end of next week. 

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 the oxidation ponds and the material inside the trickling filters after it rains.

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.

We have developed an adaptive recovery action plan [PDF, 164 KB] to provide an overview of the different work streams we're working across. This plan will be updated regularly.

Check out our dedicated space for regular updates about the fire-damaged Wastewater Treatment Plant and how we are dealing with the issues. Read more on Newsline(external link)

June 22 update: Three community meetings confirmed

The Council will hold three community meetings over the next two weeks, to give residents an update on our progress at the Christchurch wastewater treatment plant and provide an opportunity at the end to ask questions.

The meeting details are:

  • Tuesday 28 June: 2pm to 3.30pm. Bromley Community Centre.
  • Tuesday 28 June: 7pm to 8.30pm. Bromley Community Centre.
  • Thursday 7 July: 7pm to 8.30pm. South Brighton Community Centre.

Staff are also in the process of organising a webinar for people who can’t attend the community meetings in person. We’ll share details of this webinar once confirmed.


June 16 update: How we’ve modified the wastewater treatment plant since the fire

A new video shows how Christchurch City Council has had to modify the Christchurch Wastewater Treatment Plant after the November fire reduced its capacity to effectively treat wastewater by about 60 per cent.

Council staff and contractors have added poly-dosing measures, converted two of the plant’s four clarifiers into aeration basins, and are about to complete installing large underground pipes that bypass the damaged trickling filters.

Sixteen new pumps are also in the process of being installed, which will pump the wastewater from the aeration basins over to the clarifiers. This will greatly improve the effectiveness of the treatment process.

Once all of this infrastructure is in place and operating effectively, the overall quality of the wastewater will gradually improve before it enters the oxidation ponds.

The smell

Treatment plant 
The smell is coming from two sources – the trickling filters where the fire occurred and the oxidation ponds. We’re working to have both issues resolved by the coming summer.

Oxidation ponds
The fire severely damaged the trickling filters so we lost a critical part of our wastewater treatment process. As a result, poorer quality effluent is being discharged into the oxidation ponds, so the ponds began to smell. If you remember Bromley in the 1960s and 70s, that smell would be very familiar.

Immediately after the fire, we began adding hydrogen peroxide to the wastewater flowing into the oxidation ponds to maximise the oxygen saturation in the water and minimise the potential smells.

Churning additional oxygen into the wastewater is key to improving the quality of the effluent being discharged to the oxidation ponds. We have sourced aerators from different parts of the world to do this and have converted two of the plant’s four clarifiers into aeration basins using this equipment.

The equipment arrived in the country in late February, was assembled and then lifted into the basins in mid-March. The aerators were turned on in early April(external link). It will take between four and six weeks for the aeration basins to adjust and stabilise to the new treatment process. 

Air-quality testing

Since April 28, we’ve taken weekly samples from multiple sites, both at the plant and in the neighbourhood.  We also added extra sample locations based on the wind direction. 

 This work clearly identified reduced sulphur compounds (RSC) as the main cause of the odours. RSC are a complex group of substances that have a strong odour, even in low amounts. The monitoring found extremely odorous compounds, such as methyl mercaptan and hydrogen sulphide, present in varying concentrations, depending on the weather and wind direction.  

On the week beginning Monday 30 May, we started using a hydrogen sulphide meter at Bromley School. These meters continuously monitor very low levels of hydrogen sulphide in the air. The trial has been successful and we are leasing two extra meters and will purchase more.

We will be ordering up to 10 hydrogen sulphide meters for deployment around the Wastewater Treatment Plant site and across the neighbouring residential areas. Once we have these meters in place we will have a much better understanding of the different types and levels of odours that people are being exposed to over time.

By June 17, we will have collected six weeks of data. We will review the programme in collaboration with Environment Canterbury and the Medical Officer of Health, this will also help us determine next steps.


The trickling filters

During the 1 November 2021 fire, the roofs on the trickling filters were destroyed. Immediately after the fire, the burnt plastic media housed inside the round concrete trickling filters gave off an acrid smell.

That smell largely went away but over time the material inside the filters has started to putrefy. When it rains the filter media gets wet and the organic matter trapped within the media putrefies, releasing a pungent odour until it dries.

Removing the filters
We had to carry out an extensive investigation into the fire and the damage it caused and work through an insurance claim, all of which has taken time. Other parties involved have also been carrying out their own investigations.

We needed to fully understand the damage to inform our remedial options, but our insurer has now agreed that the filter media needs to be removed regardless of whether the end result is a repair or a rebuild.

Demolishing the filters
We may end up having to demolish the filters. However, the material inside the filters is classed as a hazardous material and the concrete structures are huge – each is about three storeys high and 55 metres wide. We need to make sure that whatever we end up doing is safe for nearby residents, our contractors and the environment.

The material inside the trickling filters
The bulk of the material is a mix of plastic and biomass, which was used to help treat the sewage being processed through the plant. Some of the biomass within the tricking filters is rotting and that is causing the stench.

Removing the material from inside the trickling filters
Southern Demolition and Salvage Ltd started work on-site on Thursday 12 May. They're working six days a week, 12 hours per day, to remove the rotting material from the fire-damaged tricking filters at the Christchurch Wastewater Treatment Plant. Work is expected to be completed within four months. This means by early September one of the main sources of stench from the plant will have been eliminated.

It’s a complex task as the trickling filters have 8 metre-high concrete walls and there are about 26,000 cubic metres – about the volume of 10 Olympic swimming pools – of material to remove.

The rotting material will be put through a chipper and compacted while still at the treatment plant site. Once chipped and compacted, a tough plastic membrane will be used to seal the material for transport. The membrane will line large bins for transportation.

We are using two chippers to help us process the material quickly. While the chippers are being used, residents should anticipate increased noise from the site.

Unfortunately, there are days when the smell could get worse as material deep inside the trickling filters gets exposed to the elements and starts rotting.

We know this is the last thing that residents want to hear, but at least we now have clear timeframes around when the removal work should be completed. By springtime, the stench from the plant should be much less of an issue.

Transporting the material

The waste material will be put through an on-site chipper and compacted. Once chipped and compacted, a tough plastic membrane will be used to seal the material for transport. The membrane will line large bins for transportation. 

Once sealed, we believe the stench coming from the material will be contained inside the plastic capsule.

The trucks will depart the Plant and travel along Breezes Road and ANZAC Drive before passing nearby several residential areas such as QE11 and Prestons subdivision. They will then travel along onto SH1 through Woodend and Amberley before getting to Kate Valley Landfill.

Once the trucks arrive at Kate Valley Landfill, the sealed membranes will be deposited in the landfill area and covered with inert material, e.g. soil.

The trucks will make deliveries to Kate Valley Landfill during it's opening hours. Kate Valley Landfill’s special waste operation is open Monday to Friday 7:45am-3:30pm. 

Kate Valley Landfill is a regional waste disposal and energy park facility in North Canterbury. The 37-hectare site operates to international standards, fully compliant with New Zealand landfill guidelines and the US Environmental Protection Agency and European Union standards for municipal waste landfills. For more information, visit transwastecanterbury.co.nz/

Kate Valley Landfill run two separate waste streams – General Waste from several transfer stations in the region, and Special Waste, which is waste that could not be sent through transfer stations, due to either its offensive or adverse health and safety characteristics. The deliveries of material, classified as special waste, from the Wastewater Treatment Plant will not impact or compromise its operations.

Timeline to replace the trickling filters
It’s likely to be years before we’re able to fully rebuild or replace the trickling filters.


The fire

The cause of the fire
Investigations are ongoing into the cause and origin of the fire.  Due to the complexity of the investigation, and the fact other parties are involved, we are not in a position to share any further information at this stage.

Insurance
We have been in constant communication with our insurer since the fire. The wastewater treatment plant was fully insured. Our insurer has accepted our claim but a settlement has not yet been reached. Investigations are still determining whether the trickling filters are a rebuild or a repair.


Operational

Running the wastewater treatment plant without the trickling filters
We have modified the plant so that we can bypass the trickling filters.

As mentioned earlier, we have converted two of the plant’s four clarifiers into aeration basins. Once wastewater passes through these new aeration basins, submersible pumps will push the wastewater through to the remaining two clarifier tanks.

The new system is close to being fully commissioned. The new aeration basins will not fully compensate for the treatment work that was previously undertaken by the trickling filters. However, they will greatly improve the quality of the wastewater being discharged into the oxidation ponds and the overall biological health of the ponds.

We will be closely monitoring the water quality in the ponds to assess the effectiveness of the aeration basins. If we need to, we will install more aerators in the oxidation ponds to further improve the water quality.


The Community Support Fund

Accessing the fund
The Wastewater Treatment Plant Fire Support Package opened on Monday 30 May 2022, so that eligible residents can apply for a $200 support payment. 

Our community partners can allocate the funding on request from eligible households. 

If you’re visiting one of our community providers to collect the support funding, you’ll need to bring proof of your address and a photo ID.

Covid-19 protocols are also compulsory at each of the centres, and although there’s no need to book a time, we recommend calling in advance to find out how busy the providers are.

The four providers are:

  • Ngā Hau E Whā (250 Pages Road) is open from 9am to 3pm. They’ve requested people park in the rear car park behind the Marae and collect the grants from the Totara Room. Phone (03) 382 6628.
  • He Waka Tapu (161 Pages Road) is open from 8.30am to 5pm. Phone 03 373 8150.
  • Bromley Community Centre (45 Bromley Road) is open from 9am to 2.30pm. Phone 03 389 1657.
  • The Loft (Level 1, Eastgate Shopping Centre) is open from 9am to 5pm. Phone 0800 THE LOFT (0800 865 638).

The contribution is to assist in covering costs for residents related to the odour, including laundry services, doctor appointments, vet appointments, heat pump cleaning, the purchase of appliances and firewood, and increased power use. 

We know that those closest to the plant are experiencing the most intensive stench. This is confirmed by our odour monitoring and the odour complaints received. The highest number and highest frequency of complaints recorded are from within the area bordered by Buckleys Rd, Pages Rd, SH74 and Linwood Ave. We completely understand that the situation changes and different residents will be subjected to the stench at different times, depending on the weather conditions and wind direction.

We’re also working with the Ministry of Education to provide support to schools and early learning centres in the area. Specific support and activities is still being finalised.

Creating the fund
Money for the Wastewater Treatment Plant Fire Support Package is sourced through operational savings the Council has made over the past year. It won’t have any impact on rates.

The Council considered providing this support via a rates rebate. However, they are not recommending that because a rates rebate would target property owners rather than the people living in the homes (ie renters).

Work began on-site on 12 May, with site establishment and ramp construction occurring over the first four weeks.

The material from the trickling filters will be removed between weeks four and 17, with work expected to be finished by early September 2022.

Floor pad, pipe removal and back-filling of the two trickling filters will take place from weeks 14 to 27, with the entire project completed by December 2022.

Here is a timeline to remove the material from inside the trickling filters.

Timeline of key events and decisions

1 November 2021

Emergency Services respond to a fire at the Wastewater Treatment Plant in Bromley. Both of the trickling roof filters collapse.

The damage can't be assessed properly until the fire is completely out.

4 November 2021

The Council installs a sprinkler system to get rid of hot spots and help reduce the smell.

The Council also begins working on an adaptive management plan to figure out the best possible outcome for the discharge of wastewater from the plant.

26 November 2021

The fire is officially completely extinguished by the fire service.

The Council identifies the need to remove the two trickling filters. Both filters store 13,000 cubic metres of material.

The Council starts using misters and poly aluminium chloride - an odourless powder that dissolves in water - to help suppress the smell.  Poly dosing also settles more of the suspended solids in the wastewater, improving the water quality as it progresses through the plants.

Hydrogen peroxide - a  compound that naturally breaks down into water and oxygen – starts to be added to the wastewater before it’s discharged into the oxidation ponds.

6 December 2021

The Council completes a successful trial to remove a section of the fire-damaged media from the plant.

This means that the Council can begin assessing the stability of the structures.

17 December 2021

Council staff plan to convert two of the plant’s four clarifier tanks (or secondary contact) into aeration tanks.

Installing four aerators in each of the two tanks will help decrease the bad smells and improve the quality of the wastewater being discharged.

The Council anticipates that it will be years before the trickling filters can be replaced or rebuilt.

14 February 2022

Aeration components begin to arrive and we're able to implement our interim plan to minimise odours from the fire-damaged plant.

16 March 2022

Eight aerators are installed in two of the plant’s four clarifiers.

Soon afterward, increased odours from the trickling filters are detected after wet weather. It's determined that the acute stench is caused by the material inside the trickling filters rotting and drying out.

6 April 2022

The aerators installed in March are turned on.

12 April 2022

The Council decides to fast-track the appointment of a contractor to remove the burnt filter material from the Bromley Wastewater Treatment Plant.

3 May 2022

Independent testing to better understand the odours from around the fire-damaged Christchurch Wastewater Treatment Plant detects small amounts of hydrogen sulphide and methyl mercaptan.

May 2022

Filter media removal work starts

26 May 2022

Council confirms community support package for 3,380 of the most-affected residents.

3 June 2022

Southern Demolition and Salvage Limited conduct a test run, removing and transporting the burnt trickling filter material on Friday 3 and Saturday 4 June.

June 6 2022

Work to remove the trickling filter begins.

September 2022

Filter media removal expected to be completed.

22 June update: Three community meetings confirmed

The Council will hold three community meetings over the next two weeks, to give residents an update on our progress at the Christchurch wastewater treatment plant and provide an opportunity at the end to ask questions.

The meeting details are:

  • Tuesday 28 June: 2pm to 3.30pm. Bromley Community Centre.
  • Tuesday 28 June: 7pm to 8.30pm. Bromley Community Centre.
  • Thursday 7 July: 7pm to 8.30pm. South Brighton Community Centre.

Staff are also in the process of organising a webinar for people who can’t attend the community meetings in person. We’ll share details of this webinar once confirmed.


15 June update: How to access the Community Support Package if you are out-of-zone

The area eligible for the Wastewater Treatment Plant Fire Community Support Package was defined using the FIDOL system described by the Ministry for the Environment(external link) and Christchurch’s predominant wind direction.

FIDOL stands for Frequency (how often someone is exposed to the odour), Intensity (strength of the odour), Duration (length of exposure), Offensiveness (how pleasant or unpleasant the odour is), and Location (the type of land use and activities in the area).

Council staff also took into account the predominant wind direction and how that wind affects different communities.

Christchurch experiences a north-easterly wind 70% of the time (blowing the smells towards the central city) and a south-westerly about 30% of the time (blowing the odours towards the coast).

There is a small pool of discretionary funding available for people living outside the eligible zone.

When considering these applications, staff look at the FIDOL criteria, how the situation is affecting a resident’s health and well-being, their family situation, and their ability to get away from the smells.

The more specific and detailed a request is, the easier it is for the Council’s Community Partnerships’ team to consider.

If you think you qualify for the discretionary fund, contact our Community Partnerships team by emailing communitygrants@ccc.govt.nz.


30 May update: The Wastewater Treatment Plant fire support package is now available

Residents living near the wastewater treatment plant can now access community support funding.

The support package is open to all residents in the area bounded by Buckleys Road, Pages Road, SH74 and Linwood Avenue.

Residents fronting both sides of these roads are eligible for $200 of support.

If you’re visiting one of our community providers to collect the support funding, you’ll need to bring proof of your address and a photo ID.

Covid-19 protocols are also compulsory at each of the centres, and although there’s no need to book a time, we recommend calling in advance to find out how busy the providers are.

The four providers are:

  • Ngā Hau E Whā (250 Pages Road) is open from 9am to 3pm. They’ve requested people park in the rear car park behind the Marae and collect the grants from the Totara Room. Phone 03 382 6628.
  • He Waka Tapu (161 Pages Road) is open from 8.30am to 3pm. Phone 03 373 8150.
  • Bromley Community Centre (45 Bromley Road) is open from 9am to 2.30pm. Phone 03 389 1657.
  • The Loft (Level 1, Eastgate Shopping Centre) is open from 9am to 5pm. Phone 0800 THE LOFT (0800 865 638).

Please note that none of our providers will be open on Saturday 4 June or Monday 6 June due to Queen's Birthday Weekend. 

The contribution is to assist in covering costs for residents related to the odour, including laundry services, doctor appointments, vet appointments, heat pump cleaning, the purchase of appliances and firewood, and increased power use. 

We know that those closest to the plant are experiencing the most intensive stench. This is confirmed by our odour monitoring and the odour complaints received.

We completely understand that the situation changes and different residents will be subjected to the stench at different times, depending on the weather conditions and wind direction.

We’re also meeting with the Ministry of Education, schools and early learning centres in the area to discuss the support we could offer. Specific support and activities are still being finalised.

Creating the fund

Money for the Wastewater Treatment Plant Fire Support Package is sourced through operational savings the Council has made over the past year. It won’t have any impact on rates.

The Council considered providing this support via a rates rebate. However, they are not recommending that because a rates rebate would target property owners rather than the people living in the homes (ie renters).

We have undertaken an air monitoring programme over the past five weeks. We want to:

  • understand the gases contributing to the odour
  • identify the source of these gases (across the treatment plant site) and,
  • measure the impact of the gases at various distances from the plant.

The gases making up the odour

Sewage treatment produces a complex mix of different chemical compounds that combine to create the odours currently associated with the Christchurch Wastewater Treatment Plant. 

Since April 28, we’ve taken weekly samples from multiple sites, both at the plant and in the neighbourhood.  We also added extra sample locations based on the wind direction. 

We engaged an independent air quality specialist to provide feedback on our results and compare these to workplace and ambient air quality standards. This work clearly identified reduced sulphur compounds (RSC) as the main cause of the odours. RSC are a complex group of substances that have a strong odour, even in low amounts. The monitoring found extremely odorous compounds, such as methyl mercaptan and hydrogen sulphide, present in varying concentrations, depending on the weather and wind direction.  

So far the results of air quality sampling indicate a range of compounds detected – check the latest results below.

In the week beginning Monday 30 May, we started using a hydrogen sulphide meter at Bromley School. These meters continuously monitor very low levels of hydrogen sulphide in the air. The trial has been successful and we are leasing two extra meters and will purchase more.

By the end of next week, we will have collected six weeks of data. We will review the programme in collaboration with Environment Canterbury and the Medical Officer of Health, which will also help us determine the next steps.


The source of the odours

Immediately following the fire, the odours came from the burnt trickling filters. The smell of raw sewage also added to the odour. This came from the screening and grit tanks as the air extraction unit for this process was damaged by the fire. The issues that were causing these smells were fully resolved by the end of December 2021.

In March, the combination of wet weather followed by hot days saw an increase in strong odours from the trickling filters. Additionally, since May, the oxidation ponds have been a significant contributor to the smells. The ponds don’t perform as effectively as the temperatures drop and sunshine hours reduce.

The extraction of material from the trickling filters has begun. We’ll monitor any odours produced as this operation progresses.


The next steps

Given the successful trial of the hydrogen sulphide meter, we will be ordering up to 10 of these for deployment around the Wastewater Treatment Plant site and across the neighbouring residential areas. Once we have these meters in place we will have a much better understanding of the different types and levels of odours that people are being exposed to over time.

Here is a list of the published reports and testing results from the Christchurch Wastewater Treatment Plant.


Air quality testing


House testing results - June 2022

We've received our test results of the four houses that we sampled after concerns were raised about a black mould appearing on the exterior of some buildings near the wastewater treatment plant.

The results from a reputable external contractor have confirmed that the discolouration observed isn't due to mould. While sampling did detect the presence of various mould types, there were no spores or types outside of common mould that typically grows on the exterior of Canterbury houses. 

We're undertaking further investigations to determine what's causing the discolouration of external paint that some residents have reported. We will publish and share these results once we receive them.


Water quality testing

Here are some graphs tracking the biological oxygen demand, suspended solids, ammoniacal nitrogen, faecal coliforms, and enterococci in the oxidation ponds for the Christchurch Wastewater Treatment Plant. We'll update these graphs every week.

Biological oxygen demand

Biological oxygen demand

Dissolved oxygen is an essential element in a healthy aquatic environment. Biological Oxygen Demand (BOD5) is a measure of how much dissolved oxygen is required to breakdown organic matter in a sample.

This in turn can inform us on the environmental impact a sample (treated wastewater in this case) would have on the receiving environment.

A high measure of BOD5 indicates the sample will consume/deplete a proportionality high amount of oxygen in the environment into which it is discharged. 

Total suspended solids

Total suspended solids

Suspended solids (TSS) are those solids which are large enough to be captured in filter paper. The intention is to provide a measure of the amount of particulates and debris either organic or inorganic contained in a sample.

Clean water obviously has very few suspended solids so using clean water as a reference or desirable benchmark, we can gauge by the concentration of TSS how contaminated a sample may be without needing to find out exactly what the sample contains.

Concentrations of suspended solids in our treated wastewater discharge have increased since the November fire.

Ammoniacal Nitrogen

Ammoniacal Nitrogen

Ammonical nitrogen is a measure of ammonia in wastewater. High levels of ammonia are toxic to fish and other aquatic life.

All sample results for ammoniacal nitrogen over the last 12 months are fully compliant and within the limits set by ECAN in City Councils treated wastewater discharge consent.

Faecal Coliform and Enterococci

Enterococci

Faecal Coliform

Faecal coliforms are bacteria that originate in the intestines of warm-blooded animals and are an indicator of faecal contamination. They're commonly found in wastewater and indicate the effectiveness of the treatment.

Enterococci are pathogenic bacteria. If the concentration in any sample is above the standard a second sample must be collected within 24 hours. Two samples above the standard require notification to Environment Canterbury and the Medical Officer of Health.

Both of these bacteria can cause disease. They're commonly found in untreated wastewater (sewage), and therefore, a measure of these bacteria is a useful indicator to determine how effective a treatment system, such as our treatment plant in this case, is performing.


Meetings and minutes

21 June 2022: Wastewater Treatment Plant Communications Advisory Group minutes [PDF, 592 KB]

9 June 2022: Christchurch Waste Water Treatment Plant Odours meeting between CDHB, Environment Canterbury and Christchurch City Council.

Action points arising from the meeting:

  • Report on Summary of completed sampling to be prepared.
  • Continue deploying H2S meters.
  • Ecan make available information from SO2 and H2S monitoring when available.

Newsline stories


Newsletters

June:

May:

April:

March:

February:

December: