Saturated zones - a success story

Saturated zones - a success story

2.10.2014 - Posted by Alexa McAuley
Recently, David Knights and I helped run some bioretention design training for Blacktown City Council in Sydney. As part of the training workshops, I met the participants at the Blacktown Showground and talked to them about the bioretention system there, which we designed a couple of years ago. We talked about the design and construction process, focusing on the challenges and key lessons from this project. Despite its fair share of challenges, the bioretention system is looking great today and appears to be functioning well. This system has a saturated zone and this feature has helped it thrive despite a long dry spell over the previous months. The participants told me they had visited several other bioretention systems earlier in the day, and vegetation was struggling in all of the others.

Blacktown Showgrounds

Research on saturated zones has shown that one of their key benefits is that they provide resilience through dry spells. While fully drained systems can take some time to recover their treatment performance after a long dry spell, systems with a saturated zone have shown very little loss of performance, as long as some water remains within the system. Anecdotally we have seen much better vegetation establishment in systems with saturated zones in Sydney.