Council trialling solutions to improve Shotover effluent disposal system

Queenstown Lakes District Council (QLDC) is to begin trialling potential solutions to address current performance issues with its Shotover effluent disposal system.

The system is based on a low-pressure effluent disposal field located by Council’s Shotover Wastewater Treatment Plant. This receives municipal sewage from Queenstown, Arrowtown, Lake Hayes and Arthurs Point with treated wastewater then discharging into the disposal field, an area designed for this final stage of the process.

QLDC Property and Infrastructure General Manager Pete Hansby said there had been a decline in performance of the field over recent months resulting in some localised surface ponding of treated wastewater but confirmed this had not affected the river system.

“Since March we’ve been monitoring the system’s performance closely and conducting significant investigative work to help us understand the issues in greater detail. This has involved installing additional piezometers to measure sub-surface water levels, and using a driller to clear sediment build-up from existing inspection tubes. At no stage has treated wastewater passed directly into the Shotover River,” he said.

“Later this month we’ll move to the next stage by digging a series of test pits and trenches to inform the location and final design of remediation measures. These include excavating fine silty material that may be reducing infiltration to higher permeable sandy gravel below, installing soakage trenches, and drilling one or more soakage bores to provide further infiltration capacity within the existing field.”

In addition, Mr Hansby said Council has proposed measures to Otago Regional Council (ORC) to remediate ponding that has formed outside the disposal field’s boundary.

“We’ve been in regular contact with ORC who issued the original resource consent and are now working closely with them to secure the approvals we need to deliver this work. We are also seeking an extension to the current ORC abatement notice under which the field is currently operating,” he said.

Mr Hansby said longer-term options are available to further improve the field’s performance once the team understands the gains provided by these initial options.

ENDS|KUA MUTU.

Media contact:
03 441 1802
communications@qldc.govt.nz

FURTHER INFORMATION | Kā pāroko tāpiri:

ORC issued an abatement notice to QLDC in May 2021 as the unexpected ponding of treated wastewater is not in accordance with the resource consent granted to Council. QLDC is working closely with ORC to design a solution as outlined above.