Mayor resolved to rid of pong

Whanganui mayor Annette Main said the ongoing problems which have dogged Wanganui's wastewater treatment plant since it opened must be solved "once and for all".

"Once the New Year break is over, I am keen to speak with key industries who are needing to discharge larger than anticipated or consented amounts of trade waste into the system," Ms Main said.

"I also want to understand why the system has never worked well since it was built in 2005 and what we can put in place, both short-term and long-term, to ensure people never have to be exposed again to the smell which has caused considerable distress in recent weeks. It is my understanding that there have been ongoing issues reported since 2007 and I consider it absolutely necessary that these are addressed and solved once and for all."

In the latest report on the problem, Wanganui District Council infrastructure manager Mark Hughes said the main lagoon/pond received high sulphide waste on Friday between 6.15am and 5.02pm and an even higher sulphide content waste between 2.27am and 10am on Saturday.

He said the pond had been relatively stable for the past few days but by Saturday night it had recommenced sparging and discharging odour followed by increased surface solids production.

Yesterday surface solids were removed and production had decreased.

Sparging is the technical term for the inert gas in the pond which bubbles up through the liquid and then releases the smell.

Treatment is reducing the sparging and odour but only slowly and industries are being spoken to.

The settling lagoon/pond, while improving under bio-augmentation, had not reached stability prior to the above events.

The high sulphide waste was expected to start flowing through to that pond yesterday with a consequential decrease in performance and increase in odour.

There were no new issues with the UV plant and outfall.