Christchurch City Council is investigating diverting around 30 per cent of partially treated wastewater to the existing ocean outfall in a bid to reduce the ongoing stench from the fire damaged Bromley Wastewater Treatment Plant.

Christchurch Mayor Phil Mauger said the ponds were under severe pressure.

“It is no surprise to the people out that side of town of Christchurch for that matter that the ponds are in trouble,” he said.

“We’ve got six ponds and already four of them are in very bad health. If we keep going the rate we’re going we could have all six of them red and I don’t want that.”

He said the council could not afford to wait for conditions to improve. “We can’t be sitting back for the next 2 and a half years going oh it’s raining too much oh there’s not enough sun,” Mauger said.

“We’ve got to do something. Something has to be done.”

Under the proposal, wastewater would be intercepted and pumped through an existing pipeline toward the ocean outfall rather than entering the overloaded ponds. Mauger said reducing the inflow would ease pressure on the system.

“You take 30 per cent of the problem away, it has to be better,” he said.

“We got the abatement notice from Environment Canterbury last Friday,” he said.

“They’re working with us. They’re doing the paperwork and what I’d like to see is the green buttons pressed on starting up this pump at the same time the Environment Canterbury paperwork comes through.”

He said the burning rubber smell reported across parts of Christchurch was caused by dying algae in the ponds releasing hydrogen sulphide gas.

“If you drive past the ponds and they’re green, they’re okay. If you drive past and they’re black, the algae is dying and it’s emitting this hydrogen sulphide,” Mauger said.

“It comes down to it, we owe the people in the east. We’ve got to do something,” he said. “I’m confident that it’ll work. I’ll hang my hat on it.”

Environment Director of Operations Brett Aldridge said “while Environment Canterbury is aware of a number of proposals being considered by the Christchurch City Council, we have not had any formal consultation about this proposal. We are very surprised and concerned this has been announced without those detailed discussions.

“Environment Canterbury is meeting with CCC on Wednesday, when we expect to hear about their plans following our abatement notice sent last Thursday. Environment Canterbury also expects the City Council to engage with mana whenua on cultural impacts on their plans. We haven’t been given any details regarding this proposal so can’t speculate. There are provisions under the RMA that are available to the CCC to do works under emergency. They have a current resource consent to discharge treated wastewater. Anything outside of the standards required by that consent would require a variation or new consent.”