Evaluating the Effectiveness of Stormwater Quality Improvement Devices (SQIDs) in Sub-Tropical Conditions

Abstract

Stormwater quality improvement devices (SQIDs) are frequently installed to improve the water quality of runoff to match particular water quality objectives (WQOs). However, there is a lack of data to evaluate the functioning and performance of these systems, particularly in sub-tropical climates. The primary aim of this study was to collect such data. Another aim was to establish baseline monitoring of an urban catchment before the installation of SQIDs and to forecast the improvement to the water quality after installation. This study investigates the performance of two SQIDs (a pond and wetland) within a treatment train that has been retrofitted into a sub-tropical urban catchment (Waterbird Park) on the Gold Coast, Queensland, Australia. The method used to evaluate the effectiveness of this system was through rainfall events, sampling of the inlets to the pond, its outlet and the outlet of the wetland. Sampling was conducted through the use of automatic sampling devices, before the retrofit, during the construction phase and after the construction of the treatment train. A secondary study was conducted on a separate catchment, (Discovery Park), in which no SQIDs were installed. The Discovery Park site was used as a baseline study, where the objective was to estimate the likely improvement that a lake and wetland treatment train would have at that site.