Author(s): Greg Stuart; Franz Thomsen; Simon Mortensen; Sayed Khan; Anna Hollingsworth; Matt Pollard; Bill Capati; Rodger Tomlinson; Sally Kirkpatrick
Linked Author(s): Rodger Tomlinson
Keywords: Decision Support System; Water quality; Optimisation
Abstract: 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 recycled water is released at the Gold Coast Seaway, a man-made channel connecting the Broadwater Estuary with the Pacific Ocean, on an outgoing tide in order for the plume to be dispersed before the tide changes and re-enters the Broadwater estuary. Rapid population growth over the past decade has placed increasing demands on the receiving waters for the release of the City’s excess recycled water. To manage this growing demand an investigation of the capacity of the Broadwater to assimilate a greater volume of recycled water over a longer release period was undertaken in 2007. As an outcome of the Broadwater Assimilative Capacity Study, the Queensland Environmental Protection Agency granted Gold Coast Water’s application for an extension of the existing license from 10.5 hours per day to 13.3 hours per day from the Coombabah wastewater treatment plant (WWTP). The Seaway Smart Release Project is designed to optimise the release of the recycled water from the City’s main WWTP, Coombabah, in order to minimise the impact to the estuarine water quality and maximise the cost efficiency of pumping. In order to achieve this, an optimisation study that involves water quality monitoring, numerical modelling and a web based operational decision support system is underway. An intensive monitoring campaign provided information on water levels, currents, winds, waves, nutrients and bacterial levels within the Broadwater. These data were then used to calibrate and verify numerical models using the MIKE by DHI suite of software. The Decision Support System will then collect continually measured data such as water levels, interacts with the WWTP SCADA system, run the numerical models and provide the optimal time window to release the required amount of recycled water from the WWTP within the Queensland Environmental Protection Agency license specifications.