'We owe it to them': Christchurch Mayor on mitigating Bromley stench

Christchurch City Council (CCC) is investigating a plan to pipe nearly one-third of Bromley’s treated wastewater directly into the ocean outfall to relieve a system that has been "running on a knife edge" for years.

The city’s wastewater treatment plant was severely damaged by fire in 2021. Recent cooler temperatures and high rainfall have caused oxygen and algae levels in the oxidation ponds to plummet, resulting in a spike in odours. 

The council was issued with an abatement notice last week after Environment Canterbury (the Regional Council) received more than 4,500 complaints about the smell in the past month.

Mayor Phil Mauger told rova he’s proposing to take almost one-third of the wastewater load away from the struggling ponds to divert the system and reduce the odour. 

“Out of the six oxidation ponds, four are struggling because they’re getting too much load," Mayor Mauger explained. 

“All I’m suggesting is we take 30 percent of that treated water and pipe it around to the ocean outfall, and it will then meet up with the other 60 percent that has gone through the ponds - so it will give the ponds a bit of a breather".

He believes the bypass is a "very quick and temporary fix" involving a 600mm pipe laid on the surface that could be operational within months if approved.

To ensure the diverted water is safe, CCC plans to add chlorine to the partially treated wastewater before it reaches the ocean outfall.

"We'll treat it with some chlorine so that it’s even in better condition when it gets to go out to the ocean," Mauger said. He insisted the move would not exceed the city's permitted activity levels for ocean discharge.

For the residents of Bromley who have endured the smell for years, the Mayor had a message of hope, noting the bypass could remain in place for up to two and a half years while the new activated sludge plant is completed.

"I was over there on the weekend... and I got a tiny whiff of what’s going on," Mauger said. "If these people have got to live in that for the next two years on and off, we’ve got to do something. We owe it to those people over there for sure".

CCC is set to meet with Envrionment Canterbury and mana whenua tomorrow to further discuss the proposal.

Image credit: Christchurch City Council