Queenstown Lakes District Council infrastructure general manager Tony Avery. Photo: RNZ / Marika Khabazi
The Queenstown Lakes District Council has received two abatement notices following a series of failures at Wānaka's wastewater treatment plant.
Heavy rain hit last month while the Project Pure Wastewater Plant was being upgraded and working at reduced capacity, causing nitrogen levels to spike and treated wastewater to flood disposal fields and run off.
The Otago Regional Council has since issued the two notices calling for the district council to stop discharging treated wastewater to land without complying with its consent.
One of the abatement notices described effluent flowing down an access road, into a nearby property and forcing grazing stock to drive through it to access other paddocks.
Five of the last 12 consecutive sample results for total nitrogen were "very high", and at least three of them breached the consented limit this year.
District council property and infrastructure manager Tony Avery said the council was fully cooperating and trying to address the issues to become fully compliant as quickly as possible.
But he acknowledged the situation was disappointing.
"With the recent upgrade work now complete, and all three reactors operating as expected, we're already seeing material improvements in the treated wastewater quality," Avery said.
"We will continue to keep the community informed while we work through these issues."
The Otago Regional Council warned that enforcement officers might do inspections to check compliance.
The district council also reported three wastewater ponding incidents between August and early October.
Another ponding incident was reported on 28 October following the heavy rain and a mechanical failure that reduced the capacity of the plant.
The abatement notice said staff diverted process wastewater to the disposal field.
"However, the disposal field was inundated and could not cope with the volume, causing ponding and the overland flow of wastewater down an access road," the notice said.
When enforcement officers checked the plant on the same day, they estimated effluent to be about 80 millimetres deep throughout the disposal field zones, sludge with the ponded effluent, an odour on occasions and effluent flowing about 300 metres down an access road.
Some of that was discharging through a culvert and onto an adjacent property.
The effluent runoff flooded an access road to a property, forced stock from grazing areas to drive through the effluent to access other paddocks, contaminated silage and concerns were raised about the impact on the health of people, animals and the paddocks, the notice said.
The council did not rule out prosecution under the Resource Management Act if the district council did not comply.
The latest abatement notices followed a spate of recent compliance issues with two of the district council's treatment plants.
In June, the Environment Court ruled that the council must fix the issues with its Shotover Wastewater Treatment Plant after it was issued with 10 infringement notices and two abatement notices over about a year and half.
The district council has a permit for its Wānaka treatment plant to discharge no more than 26,400 cubic metres of wastewater to the disposal field per calendar day.
The groundwater quality in the bores sampled are not meant to exceed 11.3 grams per cubic metre of nitrate nitrogen.
It also has conditions requiring no ponding or surface run off of treated wastewater and does not allow the discharge of sludge to land or water apart from to an approved landfill.
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