Cunnamulla Sewage Treatment Plant Upgrade

About the project

To meet environmental discharge targets, Pensar was engaged to complete the design and construction of a new wastewater treatment plant in the Paroo Shire. This was necessary as the existing plant was unable to meet effluent discharge requirements, did not enable irrigation reuse and was unable to handle increased inflows due to growth in the region. This project was a finalist in the AWA QLD Awards - Infrastructure Project Innovation (Regional).


Cunnamulla, Queensland

Client & Duration

Paroo Shire Council
February 2020 - February 2021 (O&M ongoing)

Project Scope

Construction of a new STP including;

  • Inlet pump station
  • Inlet works (screenings and grit removal)
  • Balancing tanks
  • RBC secondary treatment
  • Lamella clarifiers
  • Integrated electrical rooms and lab areas
  • Solar system to aid in power supply for the site
  • Incinerator and compost arrangements to assist with sludge reuse/disposal


  • The remote location on the site presented challenges for labour, plant and supply of resources
  • Specific process designs were required in order to align with the needs of local residents (high water usage)
  • There is a large fluctuation in plant inflows due to the seasonal influx of tourists in the area, requiring the designs to cater for large changes in capacity
  • Careful staging and planning were necessary to avoid interface issues with nearby cultural heritage areas


  • Established a positive relationship with the local community, using local labour and suppliers.
  • Worked delivered to a high quality
  • Pensar worked closely with senior Council staff to ensure State Funding was utilised on key aspects including optioneering a large number of potential upgrade options
  • Successful staging and temporary works to enable ongoing existing plant operations, whilst the new plant was built, followed by safe demolition of the old plant, once the new plant was meeting water quality outputs
  • Full POPT conformance with water quality requirements
  • Significant local operator training with formation of SOPs and processes for the Council to utilise, along with ongoing O&M support

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