How water utilities can prepare for the rise of extreme weather events

Posted 8 May 2017

Ozwater'17 articles
With extreme weather events becoming increasingly common as a result of climate change, the water industry needs to learn how to adapt to these changing conditions, keep calm and carry on. 
An example of one utility doing this is Hunter Water, which managed to continue providing safe drinking water when a super storm coincided with major infrastructure failures. 

In April 2015 the Hunter region was hit by an east coast low that dumped 270mm of rainfall in just 48 hours, which caused flooding. Within the same time frame, Hunter Water's Grahamstown Dam rose 1000mm. 

Raw water quality at the Grahamstown Water Treatment Plant was rapidly deteriorating, and the ability to address this was hamstrung by power outages and flooding. 

Add to that two major failures in the trunk main, which cut supply off from alternative water source Chichester Dam, and it was the perfect storm. 

“Any issues with water quality from Grahamstown Dam take on another dimension when you can't just say 'okay, we'll just forget about Grahamstown for now and go with our other supply',” said Hunter Water's Abigail Morrow, a water quality scientist in Water Resource Planning.

What the utility did next will be discussed in detail at the upcoming Ozwater'17 conference.

“We implemented a number of operational changes: we had 24-hour manned operation of Grahamstown treatment plant; and we had hourly updates on key operational parameters that were being provided by the operator – Veolia – to the incident response team at Hunter Water so we could keep a really close eye on how things were tracking at the treatment plant,” Morrow said. 

“We also made changes to chemical dosing. We had enhanced coagulation where we increased the alum dose above the normal levels and we had increased chlorine dose rates, reduced flows through the treatment plant and tightened individual turbidity targets.

“All of this was aimed at dealing with the raw water quality – which was affected by the superstorm – to continue to provide treatment to a very high standard for our customers.”

While the utility weathered the storm remarkably well, Morrow said there were many valuable lessons for Hunter Water that others can learn from as well. 

“With changing climate and increasing frequency of both droughts and big storm events, this sort of occurrence might happen more often; it's definitely important to be able to deal with it appropriately and – to the extent that it's possible – plan for how you're going to respond,” she said. 

“How are you going to optimise your treatment process and keep a closer eye on how the water treatment plant is performing? How will you roll that out in a timely fashion?

“Then there's the water quality monitoring side – the importance of a well-designed, event-based monitoring program that helps you keep an eye on what's happening in your drinking water catchment, your raw water tanks and in your treated water.”

Specifically, Morrow said the event gave Hunter Water an indication of the importance of monitoring multiple microbial indicator organisms. 

“A lot of utilities and water suppliers rely on E. coli as the primary microbial indicator, but some of the data that we saw coming out of this event really showed us the importance of looking at Enterococci as well,” she said. 

Following on from Morrow's presentation at Ozwater’17, her colleague and Manager of Water Network Operations John Stanmore will discuss how the performance of the water network was affected in the wake of the storm. To learn more about this topic and to register for the conference, click here