Investigation into fire that tore through wastewater treatment plant

Monday, 1 November 2021

Roofs have collapsed as a fire rages at Christchurch's wastewater treatment plant.

Investigators are expected to comb through the wreckage of buildings on Tuesday after a devastating fire tore through Christchurch's wastewater treatment plant.

Residents were evacuated and health officials issued a public health warning after the blaze started at the Bromley plant just after 3pm on Monday, causing the collapse of the roofs of two buildings used for filtration and forcing the site’s evacuation.

Almost 50 firefighters battled the blaze, which sent a huge plume of black smoke across the city and caused an acrid stench for kilometres, triggering health warnings.

Witnesses described hearing an explosion and nearby residents had ash and chunks of material fall into their yards, prompting the city council to confirm there was no asbestos at the site to allay fears.

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Firefighters tackling the blaze from a high vantage point after it destroyed the roofs of two buildings at the plant.

A woman who lives not far from the treatment plant said her house was “engulfed in smoke”, forcing her to flee with her partner and two children and take refuge in another suburb.

The fire is believed to have started on the roof of a building known as a trickling filter, before jumping across to the roof of a second similar building, said a spokeswoman for Christchurch City Council, which owns the treatment plant.

At least eight crews were called to tackle the blaze at the wastewater plant.

Contractors were working on the roof when the fire broke out but no one was injured.

Eight fire trucks were called to tackle the blaze, a Fire and Emergency NZ spokesman said, and residents living down-wind from the site were urged to close doors and windows, while others were asked to stay away from the area.

A huge plume of smoke from the wastewater treatment plant stretched far across the city on Monday afternoon.

A person was also treated at the scene for minor injuries, a St John spokeswoman later confirmed.

The blaze was eventually brought under control about 6pm, though smoke was expected to linger for some hours, the fire still active. The fire service would likely remain on site throughout the night, the spokesman said.

Fire broke out at the Christchurch wastewater treatment plant in Bromley.

The extent of the smoke caused Canterbury District Health Board to issue a public health warning on Monday afternoon.

“Air around this location is smoky and there is potential that people who are sensitive to smoke – such as those with heart or lung conditions, pregnant women, young children and the elderly – may experience symptoms including coughing, shortness of breath or eye, nose and throat irritation,” Canterbury medical officer of health Dr Cheryl Brunton said.

Exposure to smoke could worsen pre-existing health conditions such as asthma and heart disease, she said, while people affected by the smoke should close windows and doors and stay indoors.

The smell, which some likened to burning rubber, was so bad in the central city that an apology was broadcast to people inside the main library, Tūranga.

Those living nearby bore the brunt.

Ashley Nutley and her children fled their Linwood home after it became engulfed in black smoke.

Bromley resident and mother of two young children Ashley Nutley said she and her flatmate Brad Sanders fled their home at about 4pm after it became engulfed in smoke, Sanders suffering an asthma attack after inhaling some.

Nutley said the pair, who live on Rudds Road in Linwood, went out to see what was causing the smoke and a police officer in Maces Rd told them to leave their house and the area.

“She said she’s not sure if it’s chemical, if it’s toxic, and if I was getting smoked out to get my kids and go.”

They returned to the house to collect some food and medications.

Residents were evacuated and health authorities issued a warning to those living nearby.

“We just saw huge black plumes of smoke coming over the house and within five minutes we couldn't shut the doors and windows fast enough. We could barely see to get to our car.”

Nutley said she was fortunate Sanders was in the house at the time, as he had a car.

“It was lucky he was there or otherwise me and the kids would have been stuck there.”

The fire jumped from the roof of one building to another.

The pair took refuge at a friend’s place in St Albans and were unsure when they would be able to return home. “We’ve got nowhere to go, that’s where we live.”

Another Rudds Rd resident, who did not want to be named, said she was concerned about large chunks of ash that had fallen on her yard. She went outside to investigate and said her eyes were still stinging from the smoke.

The woman said her house stank of smoke, despite having all the doors and windows closed.

The fire left the plant operating at limited capacity, and council water boss Helen Beaumont said staff were assessing the situation. Engineers would look at the operation of the plant once the fire service gave them access.

The acrid stench of smoke reached the central city, where peopled reported it smelling like burning rubber.

“We can bypass the trickling filters and this shouldn’t affect the capacity of the plant. People can continue to flush their toilets as normal.”

The Christchurch wastewater treatment plant processes wastewater from across the city.

It suffered significant damage in the 2011 earthquake, meaning only about 30 per cent of the normal daily level of sewage was able to be processed.

About $20 million was spent repairing 1.6 kilometres of embankments at the sewage ponds.

A plume of smoke billowed across the city and could be seen across central Christchurch from the wastewater fire.

Trickling filters are part of the wastewater treatment process. Water from sedimentation tanks is pumped up to the top of the filters where it is evenly spread over the surface of the filters.

Bacterial slime grows within the filters and consumes the nutrients in the wastewater. As more flow is pumped into the filters, the slime is washed off as a floating solid.

Christchurch city councillor Phil Mauger, who helped build the trickling filters, said they were filled with honeycomb-like plastic and water trickled through them.

The trickling filters were built in the 1960s and 70s. The roofs were installed in the 1980s.

Beaumont would not comment on what work contractors were carrying out when the fire began and said this was part of the fire investigation.

A huge plume of black smoke billows across Christchurch from the burning wastewater treatment plant.

A woman in Carters Road – a stone’s throw away from the back of the sewage plant – said she saw flames from her backyard and heard the structures go “boom”.

Sarah Tobin, who lives near the site, said she was alerted to the smoke by her step-daughter and was taking videos when the roof of the first trickling filter collapsed.

“We’ve lived here for a few years and the [trickling filter] domes have always been there, and now they’re not … it’s a little bit surreal,” she said.

Tobin said the fire appeared to be under control by about 4.30pm and the smoke had stopped.

Christchurch resident Jason Lopas said he drove past the blaze at the water treatment plant not long after it started.

People walking by told him they thought they’d heard an explosion before the flames erupted.

Lopas said he saw the dome of a silo collapse, and charcoal-black smoke was billowing in the air.

“It sounded like thunder.”

“It’s huge,” he said. “It just looks like an atomic bomb has hit the ground and black smoke is roaring out of the ground.”

About 18 tenants in six homes on the Ngā Hau e Whā National Marae site had been advised by police to evacuate from their homes, Te Runanga o Nga Maata Waka chief executive Norm Dewes said.

The homes are a few hundred metres from the treatment plant, with a row of large trees on the other side of the fence line between them and the site.

Dewes said the tenants would move into the marae itself, which was further away from the fire.