Christchurch City Council is reassuring residents there is little risk of beaches becoming contaminated with untreated waste.
Photo: RNZ / Nate McKinnon
That's despite a huge fire at a sewage treatment plant, east of the city.
It sent giant plumes of thick acrid smoke into the air yesterday, which could be seen right across the city, sparking a public health alert.
The fire was in the plant's two massive trickling filter tanks, crucial infrastructure for the city's wastewater.
The council's water boss Helen Beaumont said the trickling filters would be out of action for several months.
To ensure the city's toilets could keep on flushing, alternative ways of dealing with its sewage were now being investigated.
"We may or may not get the same level of treatment but there's other things that we can do. So we can add chemical flocculants for example in the sedimentation tanks and take more of that organic material out that way, or we could turn one of the oxidation ponds over to a different process."
Beaumont said the treated sewage that wound up exiting the outlet pipe nearly two kilometres out to sea, might not be as clean as usual, and there was a chance the council would be in breach of its resource consent.
This was allowed due to the emergency nature of the breach and was unlikely to lead to any beach closures.
"We would expect to see some change. As we try different approaches and adapt the processes, we'll keep a close monitor on the suspended solids, the biological oxygen demand and the dissolved oxygen. We'll keep a close eye on what's coming out the other end of the oxidation ponds to get the best possible effluent at the other end."
On Monday Canterbury District Health Board warned the elderly, young children and those with lung or heart conditions to remain indoors to protect themselves from the smoke.
Even this morning residents were being asked to keep their windows shut.
Rachael Robinson struggled to keep the smoke out of her weatherboard home and noticed the smell even with all of the doors and windows closed.
"[It's] very toxic, sort of catches in your throat. Around about 3.20pm is when we noticed the sirens, but it was really really black even coming over the house you know, just covered up the sun and everything."
As of midday on Tuesday the fire was out, with a small crew of firefighters dampening down hotspots.
Fire and Emergency's incident commander Dave Berry told Morning Report the smoke had died down enough by Tuesday morning to allow schools to resume as normal.
"When the roof collapsed it actually sealed it off a wee bit so we've had a lot of hard work to get access, but the smoke and everything has reduced considerably."
Berry said it had yet to be determined if contractors working on the roof when the fire broke out had anything to do with causing the inferno.
Beaumont from the council said it was too early to say how much it would cost to repair or how long it would take before the plant was back up and working at full capacity.