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Floods Bill SUDS plans criticised for "creating confusion"

Environment secretary Hilary Benn was this week accused of “creating confusion” in his draft floods & water bill by focusing too much on above ground, soft sustainable drainage solutions (SUDS).

The Bill aims to increase the use of Sustainable Drainage Systems (SUDS) by ending the automatic right to connect to the sewers for surface water drainage and demanding developers put SUDS into place in new developments “wherever practicable”.

Connection will be conditional on meeting new, yet-to-be-established national standards on SUDS and drainage.

This move to more SUDS is intended to cut the volumes of water reaching sewerage treatment works and consequently reduce the risk of flooding from sewer overflows.

But the Bill has been criticised by experts for placing an emphasis on SUDS’ “soft engineering” characteristics. Soft-engineering solutions such as swales, ponds and wetlands are unpopular with developers as they take up large areas of land. Developers prefer hard engineered solutions such as attenuation tanks, which can be buried beneath parking. But the Bill says hard SUDS solutions are suitable only where “space is very restricted” and then that they “may be part of the solutuion.”

Soft SUDS may also prove unpopular with local authorities who, under the Bill, will be forced to adopt and maintain them. Soft-engineered solutions are more expensive and complex to maintain than an attenuation tank.

Despite this the Bill places a clear emphasis on soft SUDS.

“The nature of SUDS with their ‘soft engineering’, low velocities and storage characteristics means that normal and extreme levels of rainfall can be better managed, and pollutants can be retained and where possible broken down within the system, improving water quality,” says the draft Bill.

“There are a wide range of SUDS techniques, including permeable paving (including roads), swales, ponds and wetlands which can create attractive multi-functional green spaces in urban areas.”

“In areas where space is very restricted, more engineered solutions such as attenuation tanks may also be part of the solution,” it says.

But experts warned that misunderstandings about the nature of sustainable drainage systems, combined with insufficient funding for local authorities to implement the proposals effectively - may pose significant barriers to achieving widespread adoption.

“There’s a real concern that the Government may be looking through rose tinted spectacles in its definition of what SUDS means,” said British Water’s SUDS group chairman Alex Stephenson.

“To achieve proper adoption will mean tackling deeply embedded misperceptions about the nature of SUDS being closely associated only with ‘natural’ or soft solutions such as swales, ponds or wetlands. Otherwise many projects will be stopped in their tracks as being unworkable before they have even begun.

“It will be vital for industry to work closely with Government to ensure sensible provisions within the new national standards that enable both soft and hard engineered storage and treatment technologies to be used as appropriate to deal with polluted stormwater runoff and to slow flood waters down before they enter the sewers.

“Giving local authorities new powers to assess and manage local flood risk is the right way forward and they are keen to embrace the opportunity for stronger leadership.  But there has been widespread concern that the move will be ineffective unless the Government provides more money to establish local authority flood engineers. 

“Building the adequate technical knowledge and engineering expertise will take time, recruitment, practical guidance - and a significant amount of education about the nature of SUDS.  This is necessary both within the Environment Agency in its strategic guidance role and within the new SUDS Approving Boards. It’s critical that work starts now to prepare for these changes, rather than waiting for the bill to become law.” 

Hard SUDS provider Polypipe agreed.

“Although the draft Bill is a step in the right direction in helping the UK manages sustainable water levels and flood risk, there again appears to be a trend to focus on above ground, soft sustainable drainage (SUDS) solutions,” said Polypipe Water Management Solutions’ general manager Jason Shingleton.

“Whilst this guidance is what the industry needs following the severe flood events of 2007, it doesn’t go far enough in embracing a wide range of other appropriate SUDS solutions. A holistic approach to water management that utilises a combination of above and below ground SUDS techniques is needed to ensure designers and engineers can implement the most appropriate solution for a particular project.

“Whichever questions are raised about the performance and capability of below ground SUDS, the truth is that the use of these solutions has been on the increase for the past five years. By focussing purely on above ground solutions the Floods and Water Management Bill could present further confusion by creating uncertainty over whether a hard or soft SUDS solution is more appropriate.”

The Flood and Water Management Bill has been drafted in response to the review carried out by Sir Michael Pitt following the devastating floods of 2007.

Two thirds of the flooding was the result of surface water runoff. More than 50,000 properties were affected, leading to a £3bn insurance bill.   

The flooding highlighted major shortcomings in the infrastructure and management of surface water drainage in the UK.

 

Readers' comments (4)

  • Bury it in the ground and forget about it?

    "Soft-engineered solutions are more expensive and complex to maintain than an attenuation tank."

    Surely the photograph at the top of this article is sufficient to disprove the above statement - just look at the excavation! This was posed as a question at a recent ICE lecture and all Quantity Surveyors who attended agreed that surface SuDS solutions were cheaper to construct. In respect of maintenance, surface features are not 'out of sight, out of mind' like soakaways and are therefore more likely to be maintained; preventing failures in the long term.

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  • I think Alex Stephenson is right in saying “Giving local authorities new powers to assess and manage local flood risk is the right way forward and they are keen to embrace the opportunity for stronger leadership. But there has been widespread concern that the move will be ineffective unless the Government provides more money to establish local authority flood engineers."

    Every practicing flood engineer knows that each project is extremely site specific (including soil type, location in watershed, local politics) so the Interim Code and future codes should take care when mandating certain technologies where they may not be applicable (i.e. in a clay area.) A possibly more productive approach would be to encourage practitioners to reference design guideline/frameworks to a library of solutions that will lead to the most appropriate solution, as well as leave room for innovative solutions involving the social, economic, and amenity aspects of 'softer' SUDS.

    In recent years pilot projects in industry and academia have tested many of the SUDS approaches and offer some valuable tools for assessment. But concerns still exist. Many of the SUDS technologies need input from multiple disciplines, especially concerning costs, so it seems that a bridging the gap between local flood engineers/consultants, planners, and government with academia for testing & establishing of best practice by region might be the most productive use of government money and energy rather than mandating a overarching methodology.

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  • Alan Sim

    I can't understand why we are devloping solutions to remove surface water, but are still flushing our toilets with clean filtered, chlorinated drinking water.
    The SUDS is not a solution and in my view is not well engineered. We should be capturing this surface water and using it again rather than trying to dispose of it. To capture it effectively would be good engineering.
    Until we find solution in how to takle water shortages, of which we are being constantly reminded, we should not be considering the disposal of ANY surface water. Only recently an article pointed out we have areas of water scarcity (affecting 25m people) worse than some areas in Spain and Morocco.
    Water metering is a first step, but must be accompanied by a structured and sensible approach and this must be accepted by all and endorsed by the Government. Grey water capture and use is the next obvious option. Make it a condition that all new housing development MUST install grey water facilities as a planning requirement. Small groups of housing could even share a single underground tank and all pumping and filtering can be provided from solar energy when available.
    I agree that SUDS may be useful for certain highway projects where there is little or no use for the surface water collected and it may not be feasible to channel this to a user. However, ANY development or landscaping that collects surface water as a result should be compelled to find a use for the water first as opposed to disposal.

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  • Katja Leyendecker

    For SUDs to work a multi-disciplinary and multi-flood-agency approach is required. This is one of the aspects that the flood and water management bill sets out to do.

    Engineers must bear in mind that SUDs are no rocket science. In fact the exact opposite is true. SUDs techniques are only recreating what nature intended to happen in the first instance.

    A lot of pragmatism and lateral thinking is required to be employed by everyone involved. Let’s see whether WE (engineers, planners, etc etc) are up to the challenge!

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