Laboratory simulations of the City of Sydney's stormwater biofilter units to assess the impact of design, fill variation and substrate amendment on pollution removal efficiency

Abstract

In 2013, Western Sydney University (WSU) formed a research partnership with the City of Sydney Council (City) to investigate the performance of street stormwater biofilters (raingardens) mainly in the Southern Sydney area. The City was in the process of constructing 21,000 square metres of bioretention systems as part of their Decentralised Water Master Plan for improving the quality of stormwater runoff to Port Jackson, the Cooks River and the historical Botany Bay. The City's program provided an excellent example for exploring urban stormwater biofiltration systems. The thesis reports on the completed laboratory component of the investigation, with the field component being ongoing. The laboratory component was intended to inform the design, potential performance and maintenance of field biofilters, and to establish a transferable simulation technology. In the laboratory biofilter simulations, synthetic stormwater was fed to 104 mm diameter soil columns with the same vertical cross-sections and fill material as the street units. Sufficient time was allowed for the development of biochemical processes, and removal results were compared with relevant local pollution reduction targets. A 104 mm column diameter minimised the edge effect associated with narrower columns, while containing the cost and spatial footprint of the equipment to facilitate technology transfer. The study concluded that simplified, low-footprint soil column simulations of decentralised water treatment devices, such as street stormwater biofilters, can be successfully applied to improvements in design, performance and maintenance cycles, with potential for the same simulation equipment to be used for performance-testing of commercial fills, avoiding subsequent costly remediation operations for field units. Overall, the study contributed materially to biofilter design and operation for purifying street stormwater runoff to promote safe and sustainable water recycling and secure high-quality environmental flows, with implications for technology transfer and hence contribution to global water security.

Date of Award	2021
Original language	English