Whanganui council hoping two projects will end wastewater plant odour issues

The wastewater treatment plant became fully operational in February 2019. Photo / NZME

Whanganui council is still battling odour issues at the city’s wastewater treatment plant, but two projects are expected to take care of “the largest sources” of the smell.

In May, Whanganui District Council chief executive David Langford said $250,000 had been fast-tracked for a carbon filter for the plant’s thermal dryer building, with the dryer being the biggest producer of odour.

Council senior wastewater engineer Tony Hooper said in a statement that the funding was now secured, and officers were going through a business case approval process.

Procurement would follow, he said.

“The timeline for design/delivery and installation of this piece of specialised equipment is dependent on the successful tenderer and what equipment is deemed most suitable for the application.”

There were nine reports of odour in February, but numbers have dropped since, with four in March, five in April and three in May.

No reports were filed in June, but there were three in July.

At a council operations and performance committee meeting last month, council senior stormwater engineer Kritzo Venter said pipes in biofilters that scrubbed the air in the dryer and “one or two other parts of the plant” had deteriorated.

The $39 million plant has been fully operational since February 2019.

“Council’s maintenance crews have been refurbishing that methodically, and we’ve found it made a difference already,” Venter said.

A council report said air discharge pipes, exposed to relatively high temperatures, had melted and deformed, obstructing air flow and ”significantly restricting overall system circulation”.

“All air discharge pipes under the bark media have since been replaced.”

Venter said other odour mitigation projects would be completed over the next two or three years, “as we get the money”.

According to the report, they included a shutdown and inspection/maintenance/cleaning of the dryer in September, and a site visit from its manufacturer next year.

Projects that were not yet budgeted or programmed involved addressing the primary pond’s bypass line ($50,000) and its biosolids storage pond ($500,000 to $1m), the report said.

Councillor Charlie Anderson said Midwest Helicopters, the closest business to the plant, had texted him during the meeting that odour was present at its site.

He said he was concerned the smell may not be completely eliminated for two or three years, during which time Air Chathams may have moved to the airport.

“The people out there have put up with hell for nine years,” Anderson said.

Air Chathams has signed a memorandum of understanding with the council to work on a business case for the relocation, but the plan remains in its early stages.

In April, council chief infrastructure officer Lance Kennedy said, historically, there had been a perception a mong people most affected by odour that they were not being heard by the council.

But the communication process had been improved, he said.

“Potentially, there is room for those calls to keep increasing.

“We’d rather hear than them not get hold of us because they think we’re going to do nothing.”

Hooper said the biofilter work and carbon filter would treat the largest sources of odour on site.

“If there continue to be complaints off-site, we will continue to work through a number of other control measures provided at the last three operations and performance committee meetings.”

Mike Tweed is a multimedia journalist at the Whanganui Chronicle. Since starting in March 2020, he has dabbled in everything from sport to music. At present his focus is local government, primarily the Whanganui District Council.