Hot-standby for manufactured water

Australians, by and large, have responded differently to the devastating drought of the past few years. The Queensland government’s response was to initiate major water management reforms. In 2005, the Beattie government established the Queensland Water Commission and set aside $9 billion to overhaul the management, distribution and marketing of water through the SE Queensland Water Grid.

The most prominent part of this initiative is the Western Corridor Recycled Water Project (WCRW), the largest infrastructure works seen in Australia since the Snowy Mountain Scheme and the third largest advanced water recycling project in the world.

The $2.4 billion WCRWP is centred on the Brisbane River basin to Moreton Bay and the Wivenhoe Dam. On completion in December 2008, it will boast more than 200 km of underground large diameter pipeline and three new advanced water treatment plants (AWTPs) at Bundamba, Luggage Point and Gibson Island and will have the capacity to produce up to 232 ML of purified recycled water — about half of the current industrial and home demand. This massive and complex project required an equally impressive electrical control system. Schneider Electric was chosen to supply the complete electrical package for all three advanced water treatment plants and pump station infrastructure, under an 18-month contract, worth more than $10 million.

The package includes a Modicon Quantum PLC control system with Citect SCADA, Connexium Industrial Ethernet equipment, Altivar 61 and 71 variable-speed drives, an Accusine active harmonic mitigation solution, kiosk transformer substations up to 3500 kVa, integrated 33 kV switchgear, 11 kV switchboards and low-voltage distribution equipment.

Chris Holmes, manager for Water Treatment at SJ Electric, was responsible for the installation of all electrical control equipment at the Bundamba 1A Plant. He says that one of the biggest challenges for his workforce was the short time frame for designing and building the system, which was done in 15 months and included one 11 kV main switchboard of 21 modules; 6 x 2.5 MVA transformers; 2 x 4000 A switchboards; 12 motor control centres and four Modicon Quantum PLCs in a hot-standby configuration. The PLCs are ethernet based with self-healing fibre-optic communication links.

Holmes says that Schneider Electric’s integrated solution and support greatly helped to minimise the significant risk engendered by this fast-track and high-profile project.
Bundamba AWTP Stage 1A was ahead of schedule and was opened in August 2007 by former Premier Peter Beattie. It supplies up to 20 ML of purified recycled water to Swanbank Power Station near Ipswich.

Stage 1B of the project was also completed ahead of schedule with water delivered to the storage dam at Tarong Power Station on 28 June 2008. This stage of the project involved an expansion of the Bundamba AWTP to a 66 megalitre capacity, more than 17 km of pipeline to supply secondary treated wastewater from Oxley and Wacol wastewater treatment plants to Bundamba AWTP and an 80 km pipeline from Bundamba to Caboonbah, as well as five massive water tanks and four pumping stations.

The Bundamba AWTP is now supplying up to 41 ML of purified recycled water a day to Swanbank, Tarong and Tarong North power stations, freeing up precious drinking water. That’s enough water to meet the water needs of 240,000 South-East Queensland residents meeting Target 170 usage levels.

According to Western Corridor Water Recycling CEO Keith Davies, the AWTPs will supply all the water needs of the Tarong and Swanbank power stations and any extra produced will be sent to Wivenhoe Dam, the main water dam for the city of Brisbane. He says the quality of the water produced will be superior to the current water quality of the dam and adds that the three new AWTPs will enable the introduction of a new, seven-barrier water treatment system that includes microfiltration, reverse osmosis and ultraviolet disinfection.

The three plants will take water from the six local council-owned wastewater treatment plants currently in operation and recycle it to a higher purity, thus also helping to improve environmental conditions in the area.

“We are helping to clean up the waterways by removing nutrients as part of our process,” Davies says.

Davies says building the grid is just the beginning of implementing Queensland’s water reform. He says the next step, when the desalination plant is completed, will be to bring the two companies currently operating desalination and water recycling together, under what will be called the Manufactured Water Authority. As is well known, desalination requires almost three times as much energy than water recycling but, Davies says, having both gives the new grid manager a choice as to which water to use.

“Much of that decision will come down to the cost of making it, which comes back to power,” Davies says and adds that the system will be closely modelled after the electricity market.

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