This past summer, communities along the River Murray in South Australia experienced flooding not seen in decades. Harnessing a combination of proactive planning, extensive infrastructure assessments and a hands-on community engagement approach, SA Water was able to largely maintain essential services throughout this generational natural event, including an uninterrupted drinking water supply.

Peaking at around 190GL per day at the South Australia/Victoria border, a significant rise in normal river flows presented an equally significant risk to SA Water’s nearby sizeable water and wastewater network operations, which are relied upon by thousands of homes and businesses.

Stretching more than 2,500km in length across three states, the River Murray is an important source of water for irrigation and agriculture, and habitat for native fish and birds. For SA Water and the communities living and working along it, the Murray is the source of billions of litres of safe and clean drinking water each year.

With half of SA Water’s 80 drinking supply systems across metropolitan and regional South Australia using water from the River Murray, the utility’s General Manager of Operations, Chris Young, said it inherently brings a sizable network of river-based treatment plants, pump stations and major pipelines.

“Having seen the significant flooding impacts faced by communities and interstate water utilities upstream, it was evident a rapid flood response was needed to protect our asset base from flood damage, and maintain water and sewer services for customers,” Mr Young said.

“This included a comprehensive assessment process to examine each of our water and wastewater assets stationed along the River Murray, allowing us to highlight any potential impacts that rising water levels posed to our normal operations and take action where required.”

Among SA Water’s most at-risk assets identified was its raw water pump station at Cowirra in South Australia’s Murraylands region, which pumps untreated water from the River Murray to the nearby water treatment plant. The resulting safe and clean drinking water is then delivered to customers in the towns of Cowirra, Pompoota and Ponde.

“With forecasts predicting water levels not seen since the 1950s, we collaborated across the organisation to design and construct a 4m high earth bank levee around the pump to isolate the infrastructure as an island,” Mr Young said.

“A further 200 one-tonne sandbags were also delivered by helicopter with assistance of the State Emergency Service to further safeguard this important infrastructure from damage. “This early intervention and creative efforts of our people ensured that normal water services were able to be maintained to hundreds of customer properties throughout the duration of this natural event, which is a terrific outcome in such complex circumstances.”

Case study: protecting Mannum’s sewers

Sitting around 90km east of Adelaide, Mannum was one of South Australia’s most impacted riverside townships as a result of the flood event. The low-lying topography of the area meant parts of SA Water’s underground sewer network and associated pumping stations were set to be inundated by rising river levels, presenting the risk of sewage overflows impacting customer properties and the surrounding environment.

“To protect the town’s wider wastewater network from damage, our operational and stakeholder engagement teams worked closely with more than 120 residents to proactively disconnect their wastewater services, temporarily preventing their ability to use showers, toilets and sinks,” Mr Young said.

“This involved inserting a bung and fibreglass seal at each customer’s sewer connection, with locals instead able to access temporary bathroom and shower facilities at our nearby operational depot.

“A further 61 customers identified in flood-affected areas were able to continue using their wastewater service throughout the flood event, and this is the result of us being able to implement temporary wastewater pumping and tank infrastructure where possible.

“Within just a matter of weeks of the flood’s peak, our crews and contract partners were able to assess and safely restore normal wastewater services to all properties, enabling them to resume using their toilets, showers, kitchen sinks and dishwashers as normal.

“This is a credit to the efforts of our team collaborating with the community of Mannum in difficult circumstances to ensure that normal services could be maintained for the largest number of customers, for the longest time possible.”

Locks and weirs get back in business

On behalf of the Murray-Darling Basin Authority, SA Water manages Locks One to Six in South Australia as well as Lock Seven at Rufus River and Lock Eight at Wangumma in New South Wales, and Lock Nine at Kulnine in Victoria. The locks and weirs play a key role in regulating the flow of water down the river system, while providing a safe channel of passage for boats, kayaks, and other river vessels.

“With water levels during the flood set to inundate all of our locks and weir structures, our River Murray Operations team took early action in closing the lock chambers, removing sections of the weirs using our on-site cranes, and disconnecting vital hydraulic and electrical cables to prevent significant damage,” Mr Young said.

“Boats could then instead safely travel across the top of the adjacent weir structure, without the need to pass through the concrete lock chamber.

“Working with the state’s Department for Environment and Water in observing the water levels for many months, our team was able to rapidly access each lock chamber to complete the necessary electrical and hydraulic testing when safe to do so, and allow each site to open for business as usual in late February and early March.

“Our team of lockmasters – or ‘lockies’ – have missed the opportunity to chat with locals and travellers using the locks throughout the busy summer months, and are excited to be back helping people on their river journey.”

SA Water provides the state’s most important and essential service – the delivery of safe, clean water and dependable sewerage services. It is a corporation owned by the people of South Australia, and is committed to providing its 1.7 million customers with trusted water services that represent excellent value. It invests $300 million a year in sustaining and enhancing its state-wide network, to ensure that it continues to play an integral role in South Australia’s social and economic development.

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