Caboolture River Nutrient Offset Project

Project summary

This $8 million project involves stabilisation and revegetation of 2.4km of eroding riverbank, across 9 separate sites in the lower Caboolture River. The project is one of Australia’s largest nutrient offsetting river rehabilitation projects in an estuarine environment.

The works will reduce the amount of nutrients entering the waterways and will offset the nutrients discharged following the sewerage treatment process from the nearby Burpengary East Sewage Treatment Plant (STP).

The project, which includes collaboration with Healthy Land and Water as construction partner, will increase biodiversity and fish habitat while stabilising sections of riverbank, and re-establishing a riparian vegetation zone.

Unitywater will be planting 30,000 seedlings and the project will provide an estimated carbon sequestration of 34 tonnes of CO₂per year and is forecast to offset 1.6 tonnes per annum of Total Nitrogen from the river.

The project will help Unitywater achieve its 2040 sustainability goals of net zero carbon emissions, net zero biosolid waste to landfill, and net zero nutrients diverted to waterways.

Media release Nov 2022

In 2018, the Department of Environment, Science and Innovation (DESI) approved Unitywater’s application to incorporate the riverbank stabilisation works as a nutrient offset.

The nutrient offset achieved from these works will offset forecast increasing nutrient discharges from the Burpengary East Sewage Treatment Plant (STP) due to population growth and development in the STP catchment.

The business case for the proposed nutrient offset works identified that establishment of the works in the lower Caboolture River is the most efficient and beneficial approach to management of nutrients.

Further to this, the business case also identified that the establishment of nutrient offset works prior to upgrade of the Burpengary East STP is a prudent investment, which will reduce the cost of treatment services by deferring investment in the performance improvement works at the STP.

The population growth in the Caboolture/Burpengary area will place a lot of extra pressure on both the environment and on our sewage infrastructure in the future. This project will offset the equivalent load of an additional 5500 people on our Burpengary East Sewerage Treatment Plant (STP).

Nutrient offsetting is a cost-effective option that provides flexibility in upgrading STPs. It enables Unitywater to make a positive contribution to our environment and community spaces, by actively working to improve the health of local waterways.

Unitywater has carried out other nutrient offsetting projects at its Yandina Creek Wetland and in the Upper Caboolture River at Bellmere.

Around 300 logs and rootballs will be used to protect the newly revegetated banks from erosion, many of which have been salvaged from clearing works along the Bruce Highway upgrade sites.

Pre-construction activities on the riverbank stabilisation will include tidal monitoring and procurement of materials and vegetation stock. Following that there will be site establishment; bulk earthworks; construction of log bank protection elements; revegetation; and establishment and maintenance of the works post-completion of construction.

Overview of riverbank restoration sites