Historically, dealing with wet weather overflows for many water utilities means upgrading pipes at significant cost.
A traditional “grey infrastructure” approach dominated by large, expensive pipes gets the job done, but it risks missing out on providing any additional benefits to the local community.
When it came to upgrading the stretch of its wastewater network along Cannery Creek in Brisbane’s north, Urban Utilities believed it could adopt a better approach.
The area around Cannery Creek is a low-lying part of the city, meaning that during heavy rain, stormwater enters the wastewater network.
“Wet weather overflows occur when stormwater infiltrates the wastewater network,” said Paul Dubowski, Senior Civil Environmental Specialist at Urban Utilities.
“When stormwater enters that network, it can exceed the capacity of the pipes, causing overflows that impact both the local community and the local environment.”
The utility wanted a solution to this problem that would not only be efficient and cost-effective, but could also be embraced by the people living and working in the local catchment area, not imposed upon them.
“The Cannery Creek project combines grey assets and nature-based solutions,” said Dubowski.
“It includes a traditional pump station to pump screened wastewater, but it also relies on two in-stream sediment basins, a 5100 m² wetland, and two 2800 m² bioretention basins.
“They’re linked up with the project’s 2 km of rising main pipe installation. Then we’re integrating other features to provide additional benefits to the community, such as 2 km of walking track, rehabilitation of Cannery Creek and addressing local minor drainage issues.”
Working in partnership with the community
As the wet weather overflows were impacting local streets and backyards during periods of heavy rain, Urban Utilities wanted to involve the local community in any upgrade to the network.
But it wanted genuine involvement, not superficial engagement.
“We asked the community what the best solution would be, and we went through a co-design process.” Dubowski said.
“It was the first time Urban Utilities had taken that leap of faith and empowered the community to make design decisions from the very beginning.”
Responding to an expression of interest to 4500 customers across the catchment to self-nominate, the Community Planning Team was formed of 26 independently selected members who were interested in being involved.
“In that early planning and design phase, the utility really took a step back,” Dubowski said.
“We empowered the community with respect to the best solutions they would like to see for the network and their local waterways.”
Weighing up the evidence provided by subject matter experts, the team returned its verdict: it strongly favoured a nature-based solution.
Until the mid-20th century, Cannery Creek had been a series of freshwater wetlands. As the surrounding land was drained and the creek became channelised, however, saltwater intruded upstream, transforming the waterway into an estuarine environment.
“The Community Planning Team understood the history of Cannery Creek and its degradation over many decades through historic development in the local catchment,” Dubowski said.
“They wanted to see that waterway return, as near as possible, to a pre-European condition.”
The Community Planning Team did consider other options, but these wouldn’t be as efficient or as cost-effective.
“We looked at nine different options for managing wet-weather overflows, including piping to Luggage Point Resource Recovery Centre,” Dubowski said.
“That was strictly a traditional grey-infrastructure solution. But if we were to take that option, the project would have cost an additional $20 million, which would ultimately have been borne by our customers. It just goes to show the value of nature-based solutions.”
Adding up the benefits
The numbers alone speak to the project’s benefits: the upgrade will see Cannery Creek go from an average of 12 overflows a year to one every 24 months. This is equivalent to a 96 per cent reduction in property overflows and a 92 per cent reduction in spills to Cannery Creek.
Water quality will also improve thanks to Urban Utilities’ adoption of an offset mechanism provided for by state legislation.
“We’re lowering the level of the overflow in the Virginia Branch Sewer, which is the main sewer pipe that runs through the catchment,” Dubowski said.
“In lowering that level, we need to do something with all those additional flows. We’re reducing 900 L per second going through that pipe, and that’s a lot of extra water that needs to go somewhere.”
“We don’t want to discharge that directly to the waterways untreated, and we can’t be piping it to the local treatment plant. So that’s how the nature-based solution idea came about.”
The approach will see the screened water treated through the sediment basins, wetland and the bioretention systems, reducing sediment and nutrients, benefitting not just Cannery Creek, but also downstream waterways including Kedron Brook and Moreton Bay.
There are additional advantages too. The rehabilitated Cannery Creek corridor will limit mosquitos currently using the area as a breeding ground. Fish will have improved habitat,the tidal extent will be reduced thereby reducing odours from the creek, the vegetated sediment basins will more closely mimic the wetlands which were historically drained, amenity will increase greatly with rehabilitation works, and the water cycle will be more resilient.
A Queensland first
The Cannery Creek upgrade is a pioneering project for Queensland in many ways, and Dubowski appreciates the opportunity to do such innovative work.
“It’s not too often you get to work on a project that’s associated with so many firsts,” he said.
“It’s the first time we’ve had a combined stormwater and wastewater discharge licence, and almost every week we’re talking about another innovation on the project with lead civil contractor Fulton Hogan and lead designers SMEC who have been instrumental in the innovations and brought incredible value to the project.”
This includes the introduction of three separate water-quality monitoring programs.
“One to make sure we’re not having any impact on the downstream receiving environments, one to validate the water quality performance of the green infrastructure, and one that we call our ‘business intelligence’ monitoring program,” Dubowski said.
The idea is to make the system an ongoing piece of work, rather than a one-off project.
“It’s a project that will, I think, inform the future direction of not just Urban Utilities but other utilities across Australia,” Dubowski said.
Find out more about Urban Utilities nature-based solution to wet weather overflows.
What aspect of this project is innovative?. Sewer systems have for millenia discharged to surface waters under certain conditions and I thought engineers greatest contribution to humanity was clean drinking water and sewage treatment. This project will in time be considered poorly conceived as screened sewage diluted with stormwater is still highly infectious and the creek will inevitably be known as s*** creek,
Local Governments across Australia have upgraded treatment plants relined sewers and upgraded pump stations to meet environmental obligations to the environment. Is it a success to negotiate a new environmental authority (ie license to polute) which has dubious environmental outcomes.
After more than 20 years in land development, I am deeply frustrated by our industry’s failure to implement at-source wastewater treatment solutions. Development projects are stalling because water authorities lack funding for infrastructure while private developers won’t invest due to shrinking profit margins. This creates a destructive cycle that halts economic growth and limits housing supply when we need it most. What’s particularly maddening is that we live in an era of unprecedented innovation, yet wastewater treatment remains stuck with outdated historical methods. The technology exists today – decentralized systems, advanced membrane bioreactors, smart monitoring – that could treat wastewater effectively at source with lower costs and better environmental outcomes. We need regulatory frameworks that incentivize innovation, financing models that work for developers, and collaboration between authorities and technology providers. Every delayed project represents lost housing opportunities and community growth while our aging centralized infrastructure continues to strain under demand. The solutions exist; we simply need the will to implement them. It’s time to break free from this outdated paradigm before more developments fail.