Massive toilet deodorisers have been introduced to Wanganui's wastewater treatment ponds in a frantic bid to cap the stench coming from the ponds.
The oval-shaped deodorisers, are each about 2m long, 1m wide and about 1m deep and weigh 250kg.
They appeared overnight as council staff and contractors worked around the clock to get the air fresheners positioned.
Overseeing the project for the Wanganui District Council is Wi-yu Longpong, installation manager for global cleaning company Hu Yooful, which has been contracted by the council in a bid to muffle the stench.
Mr Longpong told the Chronicle installing this number of giant deodorisers was a first for his company.
"The most we have put in place before is one, so getting this contract breaks new ground for us," he said.
Hu Yooful has worked on installations around the world, but this was only the second time it had done work in New Zealand.
"Our first job was putting a similar-sized deodoriser into the parliamentary debating chamber in Wellington. Very few people know we have made that installation and we are still monitoring its impact.
"These deodorisers can release a decent amount of air freshener, but we know the one in the debating chamber has been working overtime."
The deodorisers at Wanganui's malodorous ponds are set to discharge bursts of spray every 15 minutes, working off an automatic timing device that has been set up at the site. A signal is transmitted to the deodorisers, which are mounted on pontoons floating in both the upper and lower ponds.
There will be a number of fragrances sprayedinto the air above the ponds. They include Sulphide d'Amour, Coliform Catcher, Whiff o' Waste, Flatulante Delectaco and Eau de Toilet.
"There are other fragrances available, but these are the most powerful in our arsenal, so these are the ones we've brought to Wanganui," Mr Longpong said.
He said the deodorisers generally had a life of about two months and the council would monitor their effectiveness daily.
He was not prepared to say how much the deodorisers cost, but a former wastewater engineer, Varner Dumpitt, believed the council could be up for at least $2000 for each unit.
Dr Dumpitt said he based his calculations on the cost of a basic household toilet deodoriser.
"The type of deodoriser you can hang in a toilet bowl costs about $4 or $5 each. I've calculated the size of the units floating on the ponds and multiplied that by the cost of a household deodoriser, and it's about $2000 per unit."
Councillor Ray Stevens, chair Deodorisers used to tackle the stinkof the council's infrastructure and property committee, said giant 3m-tall aerosol air fresheners had been considered but were too big.
"And they created major problems when it came to health and safety of our staff," Mr Stevens said.
"We needed big ladders to get staff to the top of the aerosol cans but the biggie was pushing down on the nozzles to dispense the air freshener. The nozzles were too big, and our staff just didn't have the grunt to push down on them effectively."
The deodorisers will be switched on from 10am today, April 1.