Boss of fire-ravaged wastewater plant apologises for rotten smell - which could be gone in months
Friday, 11 February 2022
The man overseeing operations at Christchurch’s wastewater plant wants people who live nearby to know he is sorry for the unpleasant smell continuing to waft from the site.
And he said the rotten odour that pervades a large swathe of the city should be gone in the coming weeks.
Adam Twose is confident the stench will be addressed by about mid-April, when the plant’s capacity to treat sewage will likely more than double from its current ability – thanks to a multi-million dollar effort to repurpose existing infrastructure.
Two large trickling filters at the Christchurch City Council-owned plant were destroyed by a signficant fire on November 1, limiting the plant’s overall ability to treat sewage.
**READ MORE:
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* Bad smells from Christchurch's fire-ravaged wastewater plant to continue for years
* Council staff work to reduce stink from fire-damaged wastewater plant
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This has placed more strain on the city’s large oxidation ponds, causing a smell that has been noticed by residents in Bromley, Linwood, Southshore and beyond.
Residents have described the smell as rotten, pungent and very unpleasant.
“We’re sorry for what we’ve done,” Twose, the wastewater plant's operations manager, said of the smell.
“We are really trying as hard as we can and as quickly as we can to resolve the situation.”
The scale of destruction to the trickling filters and the sophistication of the treatment process was laid bare when Stuff/The Press was given a tour of the ruined plant this week.
Twose said the wastewater plant can only operate with 30 per cent of its pre-fire capacity, meaning sewage going into the oxidation ponds is not as thoroughly treated.
To address this, two large tanks are being repurposed to perform a different treatment function, at a cost of up to $8 million.
The city council has previously described this work as a “medium-term solution”.
Inside the repurposed tanks, the council will add eight large machines that have been sourced from overseas.
These machines, called aerators, will get more oxygen into the sewage to treat it.
Twose pointed out that the tanks would now be doing something they were not designed to do.
But he said the solution would lift the plant’s treatment capacity to about 75 per cent of what it was before the fire.
Twose said he was “reasonably confident” the repurposing would work.
“It should resolve the vast majority of the smell,” he said.
Repurposing the tanks and installing the eight aerators is on track for completion at the end of March.
It would then take another two to three weeks to get the system set up and fully working, Twose said.
“We’ve lost a significant treatment stage [from the fire],” Twose said. “It’s a huge thing that we’re trying to replace.
“And we're trying to do it quickly in the time of Covid where we're having to effectively go round the globe to get all the bits and pieces we need.”
Since the fire, the council has tried to control the smell coming from the plant by adding chemicals to different parts of the treatment process.
Despite what was lost in the blaze, the council has stayed within its consented limits for the quality of the treated sewage that enters the ocean, after going through the oxidation ponds.
The council remains tight-lipped over the cause of the November blaze.
Contractors were working on the roof of the filters when the blaze began.
Ken Legat of Fire Investigation Services is investigating on behalf of the city council.
Bruce Irvine, a specialist fire investigator for Fire and Emergency NZ, said last month he was finalising his report into the cause of the blaze.
He said the fire was not considered suspicious and had been deemed accidental.