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The future of stormwater management

The future of STORMWATER MANAGEMENT Featured Image

Significant challenges lie ahead for stormwater management. A number of critical factors are creating a pressing need to update and modify how we deal with our stormwater. 
MARY SEARLE BELL delves into the future.

Rising urbanisation and the effects of climate change are demanding local authorities review and revise how they deal with stormwater. Exactly what needs to be done and how we’re going to pay for it are big issues, but it is clear something must be done and soon.

Like the rest of the world, New Zealand is experiencing an increase in urbanisation. More people are living in our cities and this, exacerbated by denser housing, is significantly increasing the amount of stormwater, meaning even small storms can generate a significant amount of runoff.

Equally problematic is the amount of pollutants collected by the runoff as it flows to the drains.

In addition, climate change is bringing more extreme weather events – more storms and more droughts. So not only do stormwater facilities need to be able to cope with increased water, they also could potentially be used to collect and store water for times of need, or used to replenish aquifers and boost declining groundwater levels.

In addition, the community expectation for clean and safe water is paramount. As Water New Zealand CEO John Pfahlert says, there is an increased awareness of, and expectation for, good water quality which is now being reflected in government policy.

“The new National Policy Statement on Freshwater Management requires that within the next 15 years regional councils consult with their communities and implement plans to meet the new standards. District councils are the ones who will need to implement these rules.”

John says we can expect a shift towards a polluter-pays approach, which will see an increase in decentralised stormwater management, and an increase in private treatment devices.

Liam Foster is stormwater and flood risk management national lead at Opus International Consultants. He points out that New Zealand’s stormwater management is currently quite unregulated compared to Europe and he expects more regulation around both the quality and quantity of stormwater.

Central and critical to this is the matter of funding. John says one of the big issues facing local authorities in the coming years is the consequential operational expenditure from the effects of growth, asset renewals and increased customer expectations.

He says the challenge will be financing the required changes in rural communities where the population is declining, incomes are static and there is no rates growth to cover the costs. In larger communities that can afford to do something about it, the challenge will be retrofitting stormwater management systems to the existing urban landscape.

“The difficulty will arise from a mismatch between expected outcomes from stormwater management versus the willingness to pay for it,” says John. “This requires ongoing good communication and expectations with the community and key stakeholder groups.”

MWH’s principal technical specialist for stormwater management Allan Leahy concurs. He says local authorities need to understand what the community wants and what people are prepared to pay for in terms of stormwater management.

“This will need concerted efforts to inform the community on what the issues are (which will vary from authority to authority), what the opportunities are, how the solution can be packaged to achieve multiple outcomes, and what they will cost and who will need to pay for them.”

Opus International water utilities group manager Suman Khareedi says funding of the changes to stormwater infrastructure, needed thanks to urbanisation, climate change and technological advances, presents a huge challenge, and it will be up to local government to close the gap between ratepayers’ expectations and the available funding.

Key to this is each local authority understanding exactly what they’re dealing with. As Luke Meys, also of Opus, says, stormwater information needs to be more robust, both regarding quality and quantity, and at a regional and local level.

“There is a demand for greater and better quality of information around stormwater events.”

He also points out that central government is wanting to abdicate from paying the tab for remedying flooding and stormwater events.

According to Tonkin & Taylor principal stormwater engineer Tim Fisher, the way for local authorities to overcome the various challenges facing them will be with good science and engineering, as well as sound financial data and advice so the issues are well understood.

“Councils will need to engage with communities to explain the science, engineering and financial matters.

“From recent experiences, the assessment and planning for natural hazards (and climate change) has been a big community concern, and not without controversy… The communities need to be asked about what they value and what they want to do about these risks.

“The stormwater professional will need to understand the wider environmental context, including the natural, social, cultural and economic contexts. Decision-making will be easier and clearer when the facts are all in place.”

The consensus is there is a need to start conversations now and undertake studies around the potential future of New Zealand’s water – there is an overarching debate regarding managing quantity (too little in some areas and too much in others) versus managing quality (such as heavy metals in runoff).

Both are important, and as far as the average Kiwi is concerned, they have expectations surrounding clean water resources and access to water-based amenities that need to be met.

  • Mary Searle Bell is a freelance writer and editor.

This article was first published in the July 2016 issue of NZ Local Government Magazine.

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