Decision support systems optimising effluent release in sub tropical estuarine environment - An Australian case study

Gold Coast Water is responsible for the management of the water and wastewater assets of the City of the Gold Coast on Australia’s east coast. Treated wastewater is released at the Gold Coast Seaway on an outgoing tide inorder for the plume to be dispersed before the tide changes and renters the Broadwater estuary. Rapid population growth over the past decade has placed increasing demands on the receiving waters for the release of the City’seffluent.The Seaway SmartRelease Project is designed to optimise the release of the effluent from the City’s mainwastewater treatment plant in order to minimise the impact of the estuarine water quality and maximise the costefficiency of pumping. In order to do this an optimisation study that involves water quality monitoring,numerical modelling and a web based decision support system was conducted.An intensive monitoring campaign provided information on water levels, currents, winds, waves, nutrients andbacterial levels within the Broadwater. These data were then used to calibrate and verify numerical models usingthe MIKE by DHI suite of software. The decision support system then collects continually measured data suchas water levels, interacts with the WWTP SCADA system, runs the models in forecast mode and provides the optimal time window to release the required amount of effluent from the WWTP.The City’s increasing population means that the length of time available for releasing the water with minimalimpact may be exceeded within 5 years. Optimising the release of the treated water through monitoring, modelling and a decision support system has been an effective way of demonstrating the limited environmental impact of the expected short term increase in effluent disposal procedures. (PDF contains 5 pages)

National Oceanographic and Atmospheric Administration

U.S. EPA Coastal Management Branch

U.S. Geolgocial Survey

NOAA Sea Grant