GHD, Melbourne Water Corporation (MWC), Royal Botanic Gardens Melbourne (RBG) and Ecodynamics have worked together to design and construct a rain garden that transformed an existing Canna Bed feature within the RBG into a functioning rain garden, providing stormwater treatment in accordance with Best Practice Environmental Management Guidelines (BPEMG).

A number of lessons were learnt from this collaborative approach. The project highlighted how important collaboration and leadership are in achieving sustainable project outcomes. One of the unique outcomes was how engineering and science can be used to achieve a successful living landscape feature.

More specifically, the project found that the Canna Lily, an ornamental species, could thrive in a bioretention system, especially during dry conditions from variable and infrequent rainfall.

The project has presented a number of future opportunities, including extending the existing monitoring regime to sample both a greater number of storm events and a larger suite of contaminants such as heavy metals and hydrocarbons. Furthermore, the installation of a gross pollutant trap (GPT) upstream

of the rain garden has been identified as critical in maintaining acceptable levels of water quality and protecting the long-term viability of the rain garden. Overall, the project is a viable case study for any new WSUD project where retrofitting to existing infrastructure is being considered.