Sediment Characteristics in Stormwater Pollution Control Ponds

SummaryWetlands systems are often monitored to assess their performance during a flow through event. The spatial mapping of sediment deposition within pollution control ponds complements water quality data, providing information on the efficiency and sustainability of the system as a pollution abatement facility. The characterisation of the sediments and associated pollutants allows a better understanding of the role of sedimentation in the overall improvements to water quality. In stormwater systems, the efficiency with which pollutants such as TSS and pre-dominantly sediment-bound contaminants such as phosphorus, metals and polycyclic aromatic hydrocarbons are removed is intrinsically related to the characteristics of the sediment inflow to the wetland. The sediment-bound pollutants are known to have a higher association with the finer range of sediment sizes and targeting the removal of the appropriate particle size fraction is necessary in designing stormwater pollutant abatement facilities. This paper presents the results for two studies of sediment characteristics: the first is at the Monash University Research Wetland in Australia and the second at the Braunebach Wetland pollution abatement facility in Germany. Sediment cores were taken at regular grid intervals to identify the physical characteristics of the accumulated sediments in these wetland systems. Defining the spatial sediment deposition patterns and the associated particle size distribution provided a greater understanding of each system’s water quality improvement function. This understanding of sediment characteristics has direct implications for the management of pollution control facilities and enables modifications to be suggested for future designs.