Shotover Wastewater Treatment Plant Stage 3 upgrades

The Shotover Wastewater Treatment Plant currently services Whakatipu Basin communities of Queenstown, Arthurs Point, Frankton, Kelvin Heights, Quail Rise, Shotover Country, Lake Hayes Estate, Lake Hayes, and Arrowtown.

A third stage of upgrades to the plant are now underway to improve wastewater capacity in the district and provide for future growth through to the year 2048. Construction includes a second Modified Ludzack-Ettinger (MLE) reactor down by Shotover Delta, and a range of new equipment, technology and supporting infrastructure to help keep our district's pipes flowing.

Once complete, the new treatment process for wastewater will be handled by the two MLE reactors. This will ensure long-term compliance as more people choose to make the Whakatipu Basin their home and help to protect the environment, meeting tighter effluent consent limits if required by Otago Regional Council (ORC) in the future.

An existing oxidation pond will be repurposed as part of the works. Part of the pond will be used for improved stormwater management on site, with another area converted to act as a calamity pond in the event the treatment plant goes offline.

These upgrades will also allow the plant to receive additional wastewater flows from Jacks Point Village, Hanley Farm, Ladies Mile and an extension of the Quail Rise residential development area.

November 2025:

The new Modified Ludzack-Ettinger (MLE) reactor and clarifier at Shotover Wastewater Treatment Plant are fully operational and treating wastewater, after successful commissioning of the infrastructure.

This means the remaining oxidation pond on site is no longer receiving wastewater flows, with all wastewater now treated by the existing and new MLEs and clarifiers on site.

Work to convert one of the old oxidation ponds into a raw water calamity basin and a stormwater attenuation basin continues, and is expected to be completed by the end of November 2025.

The other two oxidation ponds and their contents need time to become inert, before they're drained and dried out before the end of 2027. Part of the southernmost pond will be converted to an additional storage area for an event where wastewater needs to be returned to the plant for reprocessing.

Measures will be put in place by McConnell Dowell to mitigate any potential stormwater, dust, noise, and odour effects during construction.

The project's carbon footprint will be reduced by reusing spoil from the site, using sustainable materials, reducing transport emissions and the amount of steel and concrete used where possible.

Crews are monitoring smell from the site and at different elevations nearby, and if required, will use aerosol cannons and lime neutralise and disperse any odour.

The Modified Ludzack-Ettinger (MLE) process sees raw sewage screened to remove the bulk of the non-degradable solids before it’s pumped through a series of tanks. The first tank starves the bacteria of oxygen, causing them to begin to break down elements in the wastewater in order to produce the oxygen they need to survive. The second tank then feeds the wastewater with an oversupply of oxygen, causing further biological processes that complete the stabilization of the organic matter, reducing the nitrogen concentration in the end product

The material is then pumped into a settling tank (a clarifier) that further separates and clarifies the resulting liquid. The processed clear water is then UV treated and pumped out of the system. Some of the remaining solids are then pumped back to the start of the process to begin it all over again, while the rest is pumped into a dewatering plant where it is dried out and removed, to be disposed of at an approved off-site location.

If you have any questions, please give us a call on 03 441 0499 or email: services@qldc.govt.nz