Shotover Wastewater Treatment Plant Upgrade

Upgrades will improve wastewater capacity in the district and provide for future growth in the area through to the year 2048.

About the project

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.

What's the latest?

Wednesday 20 March 2023

Since starting on site back in August 2023, construction crews have made great progress on upgrades to the Shotover Wastewater Treatment Plant, some of which includes:

  • Excavating over 12,000m3 of material in the area of the new plant, which will be reused on site to form new stormwater basins in the future
  • Completion of the concrete base slab for the second Modified Ludzack-Ettinger (MLE) reactor

As of March 2023, work has now started on the new clarifier tank. Later in the year, they'll start working to decommission an existing oxidation pond and use already excavated material to form new stormwater basins.

Managing construction effects

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.

Management of odour

Following reports of increased odour from the site during the current decommissioning of an existing oxidation pond, crews are now working to cover the drained area with excavated material.

We'll continue monitoring odour from the pond both on site and at different elevations around the site as the pond is taken out of service. If required, the use of lime and odour mitigation sprays may be used onsite, with sprays potentially used at an elevated level too.

About the treatment process

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.

Any questions?

If you have any questions, please give us a call on 03 441 0499 or email