Laboratory Testing of an Alternative Sand-Based Filter Media for Stormwater Biofilters
(2007 – 2009)
This project investigated the feasibility of using an alternative filter media (sand-based) for bioretention systems. Indeed, whilst biofiltration has become an increasingly popular technology for stormwater management, there are often difficulties in being able to ensure that the filter media material meets the strict specifications which have been developed (e.g. the FAWB specifications for loamy sand filter media).
Experience in building turf systems such as golf greens, race courses or sporting fields has resulted in a series of guidelines for specifying and constructing such systems, and suppliers are able to provide products of consistent quality. The approach was to start with a sand base, and to add known amounts of organic matter and fertiliser to sustain plant growth. The assumption was that adoption of this standard as an alternative filter media specification for biofiltration systems would simplify the media specifications and the sourcing of materials. This construction method would hopefully also give greater control and precision over the final media characteristics, reducing the variability which is currently observed for loamy sand based media.
This project consisted of a one year laboratory study undertaken by Monash University in collaboration with Melbourne Water and EcoDynamics. The aim of this study was to test an alternative filter media for bioretention systems based on guidelines used in the turf industry. This filter media should (i) sustain plant growth, (ii) maintain hydraulic conductivity over time, and (iii) achieve effective pollutant removal. The results were also compared with a similar study looking at loamy sand as a filter media for biofilters (undertaken by FAWB).
The results demonstrated that sand based biofilters could be used for the treatment of stormwater as an alternative to the generally recommended loamy sand based biofiltration systems. The advantages of this alternative specification are its reproducibility and reduced variability.
Key Industry Report:
Bratieres K., Fletcher T.D., Deletić A., Somes N., Gerrans D., Baer E. and Urrutiaguer M. (2009) Alternative filter media column trial. Monash University (FAWB), Melbourne Water and Ecodynamics, Australia. PDF (6.9MB)
Other Publications (link)