Monitoring Field Biofiltration Systems: Banyan Reserve Treatment Train
(2008 – current)
The Banyan Reserve Treatment Train was constructed in 2008 to treat runoff from a large catchment in Carrum Downs, a south-eastern suburb of Melbourne. Stormwater flows first pass through a sedimentation pond and wetland before entering the biofiltration system. The treated water is then collected and conveyed to the conventional stormwater drainage system.
Since this treatment train is located in the bottom of the retarding basin, a secondary objective of this monitoring project is to test whether stormwater improvement and flood prevention can be achieved within the same system.
This biofiltration system is one of the first in Australia to contain a submerged zone – a permanent pool of water at the bottom of the biofilter. An important finding to have already arisen from this project is confirmation of the importance of submerged zones for supporting a healthy plant community throughout extended dry periods. During the summer of 2008/09, when Melbourne experienced one of its longest dry spells on record, vegetation in the Banyan biofilter continued to survive and grow because the submerged zone provided a source of water.
A total of 30 wet weather events need to be monitored and tested for sediment, nutrients, metals and microorganisms. Monitoring began in January 2010 for water quality and flows, and will continue for approximately 2 years, depending on rainfall. Water level is being monitored in the biofilter so that we can determine infiltration rate.