Managing water in a fast-growing city
Cedar Grove Environmental Centre is one of Australia's most sustainable wastewater treatment plants. It forms the cornerstone of the water supply for Logan in South East Queensland.
Speaking on the Australian Water Association podcast series, Mark Vaughan, Water Partnership Manager at Logan City Council, explained the capital works challenges in this rapidly growing region.
“About 160,000 people are going to move [to the area serviced by the Cedar Grove Environmental Centre]. At the moment there are less than 5000. So we've got a very big growth path, and we've got to put in the infrastructure needed to serve that community,” he said.
Greater Flagstone within Logan City has only a very small temporary treatment plant at the moment, so the council had to start building the long term trunk infrastructure for the priority development area.
The solution was a wastewater treatment plant at Cedar Grove, which Vaughan explained is much more than the average facility.
“The licence conditions for this plant are some of the strictest regulations in Queensland. We have no net nutrient increase in the river,” he explained. “And for every kilo released, we have to offset it by a kilo and a half.”
On the site there is an advanced membrane bioreactor plant, constructed wetlands to then strip the nitrogen from the water, and a nutrient offset project.
“Upstream of the plant, there is unstable riverbanks, and we're using riverbank stabilisation to make sure that all that nutrient-ladened sediment is actually captured and doesn't get dislodged.”
Vaughan said that there was a fairly strong negative community reaction when the initial plans for the plant were revealed.
“Straightaway, what the residents group told us was that their ambition was to have an environmental focus. We surveyed the members of the group, and the most strong feedback that we got was that they wanted access to land for community benefits, and they also wanted it to be an environmental approach,” he said.
One solution Vaughan and his team came up with was to open up access by building a walking track that will allow residents to access the Logan River in an area that they haven't been able to previously.
“How much the community comes out to the site I think is a measure of how well the community accepts it,” he said.
Vaughan said that the council will continue to research the effectiveness of the plan for the wetlands to strip nitrogen from the water.
“There have been some very successful plants doing this, and we're trying to bring some certainty to some of the assumptions around the effectiveness of the wetland in actually taking the nutrients out,” he said.
The construction of the Cedar Grove Environmental Centre has been a steep learning curve for the Council, but one that Vaughan and his colleagues are grateful for.
“The main thing that I’ve learned over the project is that there's a benefit to involving the community early on. We've now got a great relationship with the Traditional Owners of the site,” he said.
“We now have around 37,000 trees that have been planted on the site as one of the council’s offset projects. Put it all together, and I think we’ve got a fantastic site out there that is a great benefit to the community.”