The smell from the Victoria Flats landfill is ''not acceptable'', and gas generated at the site has increased in the past two years, a Queenstown Lakes District Council (QLDC) consultant says.
Documents released to the Otago Daily Times by the Otago Regional Council (ORC) under the Local Government Official Information and Meetings Act show the smell has been noticed inadvertently by the regional council's own staff.
Gibbston Community Association secretary Trish Mackenzie told the Otago Daily Times in July that Gibbston residents and business owners had been putting up with the ''stench'' from the landfill for years.
An environmental engineer contracted by the QLDC, John Cocks, spoke at the association's annual meeting in June to explain what was being done to minimise the odour.
In a file note about the meeting, ORC senior environmental officer Simon Beardmore writes that Mr Cocks ''acknowledged that the odour situation is not acceptable, and it is apparent that in the last two years, the generation of gas has increased''.
''The number of complaints reflects this.''
The landfill's operator, Scope Resources, was designing a landfill gas collection and destruction system to help alleviate the problem, Mr Beardmore writes.
In July, two ORC hydrologists contacted Mr Beardmore to report the ''strong sulphur odour'' they noticed while driving along a 5km stretch of State Highway 6 between the landfill and and Gibbston.
The hydrologists told Mr Beardmore they had noticed the smell each time they passed through the area on two separate days.
Scope Resources has a long-term contract to manage the landfill on behalf of the Queenstown Lakes and Central Otago Districts Councils.
The landfill is 19km from Queenstown, between the Victoria Bridge and the Nevis Bluff.
Household, commercial, special and hazardous waste from the Wakatipu and Central Otago is buried there.
An audit in April of the QLDC's air discharge consent for the landfill by the ORC found it to be fully compliant.
However, emails between the ORC, consultants and Scope detail efforts to reduce odour levels using new sludge handling procedures and other work to ''scrub gas/odour flows in hot spots''.
Higher levels of wastewater sludge with a higher moisture content coming into the landfill than before are also pinpointed as a cause of higher gas levels.
