Water Journal : Water Journal November 2011
resource management refereed paper technical features 90 NOVEMBER 2011 water Case Study 1: January Flood Response In January 2011, a major flood occurred in South-East Queensland. Major incidents such as this will inevitably impact on key assets. Damage to multiple water treatment plants (WTPs) and water and sewage mains, chemical shortages and widespread access issues contributed to a reduced ability to deliver safe drinking water through conventional water treatment processes. Despite these challenges, the SEQ Water Grid continued to deliver safe drinking water. There was only one instance where water supply could not be provided. This occurred for three days, in one of the worst-hit areas, the Lockyer Valley, which was isolated for several days due to high flood waters. In other areas that were impacted, supplies were tankered in or bottled water supplies were delivered. Within the connected area of the SEQ Water Grid, production decreased at key water treatment plants due to operational constraints as a result of turbid raw water quality caused by the flooding. The impacts were most pronounced in central South-East Queensland. At the peak of the floods, more than 10 tonnes per second of wreckage, debris and silt flowed past the extraction points for the WTPs in the upper reaches of the Brisbane River. Impacted plants included Mt Crosby Eastbank and Westbank WTPs, the largest plants in the region and the key sources of supply for Brisbane, Ipswich and Logan. The Mt Crosby Eastbank WTP was also impacted by a mechanical issue, while production from the North Pine WTP was restricted due to poor raw water quality. These interruptions resulted in treated water storages being depleted to critical levels. In response, the Gold Coast Desalination Plant increased output to help ensure a continued supply of high-quality drinking water. After being mixed with water from other treatment plants, desalinated water was piped to Brisbane via the Southern Regional Water Pipeline to ensure maximum quality water supply. In addition to supplies from the desalination plant, water was also transferred from the Gold and Sunshine coasts into central South-East Queensland. Even with these measures in place, treated water storages fell to critical levels before the main WTPs, including Mt Crosby, came back online. Other WTPs were offline due to interrupted power supplies or inundation due to local flooding. These included Canungra, Kooralbyn, Jimna, Linville, Lowood, Esk, Somerset, Kenilworth, Woodford and Caboolture. Several of these plants are the only source of supply for surrounding towns so it became a priority to repair them. The surrounding towns were also made a priority for the delivery of bottled water and for tankers. Other challenges included the inundation of local access roads, hampering efforts to deliver key chemicals vital to the water treatment process. This caused critical chemical shortages for some water treatment plants. However, thanks to the SEQ Water Grid being used to its full extent, and the effective actions of Grid Service Providers in operating their water infrastructure under very challenging conditions, drinking water continued to be supplied to almost the entire region. Boiled water notices were issued for some towns in the Lockyer Valley and Somerset areas, along with Marburg in Ipswich. While no contamination of the water supply was confirmed, the notices were issued as a precaution. This precaution was needed while repairs to flood-damaged water infrastructure were carried out. To ensure the community continued to have access to safe drinking water, the SEQ Water Grid coordinated the emergency response through the SEQ Water Grid Emergency Response Plan. The response to the flood event involved all elements of the SEQ Water Grid. Without the infrastructure and the expertise within the Grid Service Providers, it is highly unlikely that water would have continued to be supplied to areas in Brisbane, Logan and Ipswich (with the exception of Marburg) without interruption or the need for water to be boiled before drinking. Additionally, having the skills and expertise within the Grid Service Providers, and the emergency management arrangements in place, allowed for a timely and effective response. Support was provided to the most affected entities by others, especially in South-East Queensland, through mutual aid arrangements. While improvements to these arrangements can and are being made, the overall response was sound. This is reflected in the statement by the Flood Commission of Inquiry that stated it considers that the response demonstrated by those involved in the provision of drinking water in South-East Queensland was appropriate in all the circumstances. Figure 2. Affected water treatment plants, 10 January 2011.
Water Journal December 2011
Water Journal September 2011