Monitoring Spatial and Temporal Changes in Stormwater Quality Through a Series of Treatment Trains. A case study – Golden Pond, Brisbane, Australia

摘要

Urban stormwater can be a pollution source to waterways with impacts on aquatic ecosystemrnhealth. In urbanised residential areas major pollutants are sediment and nutrients and to arnlesser extent heavy metals and hydrocarbons. Stormwater best management practice is aimedrnat reducing potential downstream impacts. Stormwater treatment devices to control or reducerntrash, sediment and nutrients include gross pollutant traps (trash tracks, CDS and ECOSOLrnunits); sediment basins, vegetated buffer strips, wetlands and ponds and biofiltration systems.rnA crucial question is “How effective are these stormwater treatment devices in improvingrnwater quality?” A case study was undertaken to evaluate the performance of several devicesrnin a ‘treatment train’ including a sediment basin, constructed wetland, pond, CDS unit,rnECOSOL unit, natural riparian wetland and a 600 m length of natural stream channel. Ourrnstudy showed that during a storm event there was little reduction in the concentration of totalrnsuspended solids throughout the treatment train due to limited detention time, however therernwas a decrease in soluble nutrients. Within 24 hours TSS in stormwater runoff was atrnbackground concentrations or lower, but nutrient concentrations had increased. The sedimentrnbasin, wetland, pond and riparian vegetation were all effective in removing these nutrients.rnDuring dry weather small amounts of NH4 and NO3 were produced in the sediment basin butrnremoved in the wetland. Stormwater via the below ground GPT’s produced higher solublernnutrients, however these were removed by the pond and riparian wetland vegetation. Duringrndry weather the riparian wetland generated NH4 and organic particulates. The existing 600mrnnatural stream, lagoons and associated vegetation were effective at removing sediment andrnnutrients to achieve Water Quality Objectives of 15mg/L TSS, 0.65mg/L TN and 0.07mg/LrnTP, at the end of the treatment train.