It is too early to determine how much Wanganui's ailing wastewater treatment plant will cost to repair but the council may be looking at raising loan monies to cover it.

Mayor Annette Main has told the Chronicle that the eventual costs could be anything from a "small" fix to a replacement of the plant.

The treatment plant, near the city's airport, started operating in 2007 but almost from the beginning it suffered malfunctions.

Since December last year the smell coming from the plant has worsened and involved the council finding quick-fix solutions to harness the odour problem.

Ms Main said up until February 4 - about two months after an overload of hydrogen sulphide was dumped into the wastewater system - $270,000 had been spent on bio-augmentation, vapourisers around the ponds' perimeter as well a dumping tonnes of lime slurry into the ponds.

All of these efforts are trying to suppress the stench being created in the sludge that has built up in the bottom of the ponds.

She said Wanganui District Council had budgeted $400,000 for chemical dosing of the ponds in 2012/13.

"We budgeted $2.4 million in the 10-Year Plan 2012-2022 but over a different timeframe and for slightly different remedial work," Ms Main said.

But now she said council officers believe that $400,000 will be exceeded by the end of March and that a further $400,000 will be required this year.

She said in that case the council will reprioritise its budgeted funding from the 2012/13 and 2013/14 years. Any extra money needed would have to come from loans.

Asked if any financial blueprint was being worked up to cover any potential major expenditure, Ms Main said it was too early to determine.

Consulting engineering company Cardno BTO was investigating a long-term outlook for the treatment plant . "The scale of the cost will be known in time for inclusion in the 2013/14 Annual Plan," she said.

- WANGANUI CHRONICLE