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After the storm: what the floods have taught us

There is no such thing as a one-size-fits-all solution to the flooding crisis experienced yet again in Australia. But there is a common approach that can help mitigate risk and prepare for the future.

The feedback from water managers around recent flood events has been characterised by shock and awe. Furthermore, it has been about how can stormwater infrastructure ever cope with the levels of water that submerged parts of towns and cities such as Byron Bay and Lismore, Brisbane and Sydney experienced.

Of course, there is no single solution for issues resulting from extreme weather events like those experienced recently. 

Not only is Australia trying to control unprecedented volumes of water, solutions also depend heavily on local conditions and challenges.

“It’s a mistake to walk into a council area and assume they all have the same problems and they all should be taking the same approach,” says John Weaver, Contracts Manager at Interflow. 

“It depends on the age of the area, on population growth, ground type and much more.

“Newcastle, for example, is an old city that has had stormwater problems amplified by earthquakes. That’s very different to a newer area like Camden, or a town like Dubbo where they have problems underneath the highways because of subsidence. Then there are other towns where many stormwater problems are caused by silt building up in the pipes.”

So, do we assume there is no solution? “Absolutely not,” Weaver says. 

The secret to success is one that can be shared between water managers everywhere. It means using recent events to create greater awareness around our stormwater infrastructure and the condition of underground assets. Furthermore, it involves the utilisation of modelling to plan future developments of water infrastructure and residential and commercial buildings.

 

Stormwater management into the future 

“Look to New Zealand for an excellent example of preparation for the effects of climate change on water infrastructure,” Weaver says. “Asset owners and town planners are focussing management strategies on flood events increasing and rising sea levels.”

“They’re doing a lot of modelling, making sure that if there are future land developments or growth corridors, they fit into what’s predicted to happen with water in the future,” he says.

Weaver says in Australia, its focus has been on water security, on getting ready for the next drought.

“It’s correct to focus on water security.” But at the same time, increasingly regular and extreme rainfall events also deserve attention, as the recent floods proved,” Weaver says.

“Directions filter down from the Commonwealth to the states and on to asset owners around water security.

He says these are typically mandated and they provide an excellent model for it to follow to successfully manage increasingly challenging stormwater issues.

 

Practical solutions for current infrastructure 

Outside of emptying dams and preparing communities, there is little that can be done in the way of an emergency response to such dramatic flood events.

The focus should instead be on developing greater awareness around the current state of existing infrastructure and putting in place a management plan that extends its useful life and improves its performance. 

“There are two sides to innovative and successful asset management,” Weaver says. “One is around building new assets and the other is around what to do with existing assets.”

“For example, a major authority that we work with is about to embark on a huge renewal program. We’re working with them and a few other contractors to come up with options to renew their assets without increasing the chances of flooding.”

Weaver says that works very well by taking an asset owner’s good ideas and running them through a review program that includes advice from highly experienced contractors. This ensures the solutions are as good as they can be.

“The most powerful insight a water manager can have is the real-time, current condition of their infrastructure,” he says.

Gradually, all stormwater assets are deteriorating. If a water manager constantly monitors those assets they will know exactly when they require maintenance. They will enjoy certainty around the order projects should be carried out and can engage with specialist contractors to plan and design solutions that extend the assets’ lives whilst improving their performance.

Such insight means asset owners will know when a swift response is required to ensure public safety as experienced in the work contracted to Interflow by Ipswich City Council to restore a failing section of pipeline running beneath a popular and busy outdoor recreational space. It also means custom solutions can be designed and developed well in advance of them becoming catastrophic, such as the bespoke renewal of the stormwater drainage culvert running beneath the bustling Brisbane Corso. Interflow’s unique structural relining of the culvert, which was exposed to the Brisbane River’s rising tides, meant costly cofferdam construction could be avoided whilst all structural requirements were met.

Additionally, more was delivered for less when a 50-year extension of life for a vital culvert running beneath a busy Sunshine Coast Council street was achieved. Without any traffic, telecommunications, electrical or water disruptions, the unique solution involving the installation of a glass-reinforced liner eliminated all need for excavation, enabling a 25 per cent cost reduction.

 

Planning for an ageing infrastructure 

Prior to the major flood events of the last several years, many Australian councils were already facing the realities of water infrastructure assets, built prior to 1970, beginning to reach the end of their life cycle. 

An Infrastructure Australia report  identified ageing infrastructure as a critical issue across Australia. 

External pressures, the report highlighted, included a growing population, a rise in single-person occupied dwellings and increasingly frequent extreme weather events.

Water managers are facing an infrastructure cliff whilst simultaneously experiencing a dramatic rise in community expectations, driven by flood and associated weather events. A proactive approach must begin with definitive insight into the condition of all parts of the infrastructure, informed by advice and input.

For more information visit Interflow’s website.

 

This article appeared in the August edition of Trenchless Australasia

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