Fresh complaints have been laid about bad smells coming from Wanaka's Project Pure wastewater treatment plant, prompting a new investigation by the Queenstown Lakes District Council.
The latest study started on Monday.
An engineer has been sent to Wanaka for a week to spend time at the site, meet the neighbours, complainants, plant designers and operators and Otago Regional Council staff.
The investigation will include the operations of the wastewater network in Wanaka, with particular emphasis on night-time operations at the pumping station.
The engineer was not spending the whole week on site but would visit frequently to assess the situation, QLDC project manager Martin O'Malley said yesterday.
"Our aim is to establish, with certainty, the cause of odours that are being detected by residents and develop a plan . . . to mitigate any further odours."
A report was expected within six weeks and would be supplied to all the parties.
An Otago Regional Council officer investigated odours at the site on November 27 and determined the plant was being operated in breach of its consent.
An infringement notice and $1000 fine were imposed on plant operator United Group.
Mr O'Malley said the odour issue was frustrating for all the parties, particularly as any further infringements could incur higher penalties.
The treatment plant is on Wanaka Airport land.
Mr O'Malley said the complaints register listed three individuals who had reported an odour.
Wanaka businessman Aaron Heath lives near the plant and has complained.
He said yesterday, when contacted, the nature of the odour was fickle.
"It varies, to be honest. It depends on wind conditions, climate - a whole raft of things. There is no science to say it is happening three times a week, once a week or once a month," he said.
The QLDC had an obligation to investigate because it had offered a resource consent condition at an Environment Court mediation that there would be "no odour", Mr Heath said.
The neighbours had accepted the condition.
Mr Heath agreed one way to resolve the issue could be to amend the ORC's consent condition so it was less absolute, but it was possible neighbours could seize the opportunity to pick up their Environment Court appeals.
Asked what that would achieve now the plant was completed, Mr Heath suggested options still existed, such as putting a roof over the plant or even the admittedly extreme option of relocating complainants.
However, he did not want to comment further on such options because it was impossible to know how to fix a smell if the cause had not been determined, he said.
