The smell lingers and lime dumping continues as Wanganui District Council battles to suppress the stink coming from its wastewater treatment ponds near the city's airport.
And yesterday the council learned that the screws were being tightened by Horizons Regional Council as it demanded more be done to stop the odour coming from the ponds.
The regional council is preparing to seek an enforcement order from the Environment Court over Wanganui's lingering odour.
Horizons had served the district council with an abatement notice requiring it "to cease causing an objectionable odour" beyond the boundary of the Landguard Bluff plant. That expired at 5pm on Thursday.
Dr Nic Peet, Horizons group manager strategy and regulation, said over the next few days compliance officers would be assessing the district council's ability to comply with this notice. That could mean further enforcement action if investigations warranted it.
An enforcement order would result in an action plan - monitored by the court - that the district council must continue to follow to address the issues at the plant.
He said it may not stifle the odour immediately but it would give the Wanganui public an assurance that the district council was continuing to do everything it could to resolve the problem.
"This step gives the community surety that the district council is doing all it can to solve the problem. It's a clear signal that council must work to find a solution."
Yesterday another 20 tonnes of hydrated lime was spread over both the upper and lower ponds of the Airport Rd treatment plant.
This is the second application of lime slurry following the first 50 tonnes dropped into the ponds last week. The lime is being used to cover the sludge accumulated in the bottom of the ponds and which is generating the smell.
Mark Hughes, the council's infrastructure manager, told the Chronicle this process would be reviewed on Tuesday.
"The 'health' of the ponds is improving but there is a way to go yet," Mr Hughes said.
"More odour will be coming from the ponds, but we hope that the intensity and frequency will continue to diminish."
On Thursday the first of the rebuilt and rewired directional aerators was installed. A second one was being installed yesterday and a third one goes into the ponds on Tuesday. Three large blowers are ready to be installed to aerate the ponds via a series of tubes below the surface.
"We'll start installing these about Wednesday next week and it will take about a week to complete this process," he said.
This time around, the council is using the Wanganui-based helicopter of Ravensdown Aerowork to drop the lime slurry.
Webster Lime of Havelock North is supplying the lime . Last week it used a Wairarapa helicopter to make the drops.
Mr Hughes said the first application was arranged at very short notice and Webster Lime called in its existing contractor.
"However, Aerowork is more conveniently located and we're pleased to have been able to bring them on board this week," he said.
Dr Peet said Horizons staff would continue monitoring the ponds and were also working with a number of residents who were keeping odour diaries.
Residents can tell Horizons whenever they smell odours coming from the plant by phoning 0508 800 800 where their details will be taken.