This page contains a Flash digital edition of a book. Alex Stephenson,

Alex has over 36 years experience in stormwater drainage design and related issues.

As well as being the UK Stormwater Director with Hydro International he is also Chairman of the SuDS focus group. He is ideally situated to keep you up to date with the industry changes and legislation.

The Beauty of a Vortex

Admiring the beauty and elegance of natural patterns and processes is something that I believe all us engineers do. The vortex is a particular object of fascination for water and drainage engineers because of its simplicity and power.

Yet, as Leonardo Da

Vinci once said: “simplicity is the ultimate sophistication” - and simplicity can take a lot of hard work for designers to achieve.

As it uses no power other than the energy of the water itself, vortex technology is inherently sustainable. It therefore feels like a very contemporary solution, yet it is well proven. Vortex flow controls are used in thousands of applications worldwide in all shapes and sizes - from giant flood prevention schemes, to everyday small-catchment drainage schemes.

Now latest step-changes in engineering development are moving the technology on once again, particularly in the design and application of the ‘Hydro- Brake’, which through its own success, has become an industry-standard term for flow controls.

National Standards

In the UK, new National Standards for Sustainable Drainage Systems (SuDS) will place increased expectations for controlling the flow and quantity of surface water in new developments. Vortex technology provides the ideal solution – but its design and specification need careful consideration to meet the required standards effectively. Compared with conventional technologies such as an orifice plate, penstock or slide gate valve, the flow of water out of a vortex flow control has much less energy per unit of cross- sectional area. It is therefore, much less likely to cause scouring or physical damage to downstream structures, protecting sensitive wetlands, ponds, basins or watercourses, even preventing damage to sewer infrastructure.

Bringing water quality back under control not only combats flooding, also but facilitates effective stormwater treatment. The reduction of peak flows causes less of a short-term shock pollutant load to the receiving waters and allows increased dilution. It’s no secret that many vortex flow controls on the market are based on Hydro-Brake® technology. The name ‘Hydro- Brake’ has become a generic term – rather like the ‘Hoover’ to vacuum cleaners, or ‘Biro’ to ballpoint pens.


specification of a ‘Hydro-Brake or equivalent’

is standard

practice to designers using industry-standard modelling software packages.

Imitation may be a sincere form of flattery, but in the case of vortex technology, substituting one product with another could lead to disaster.

Whilst the

technology may appear simple and elegant, the differences in engineering are significant.

New technology standard Now developments in vortex flow control technology by Hydro International have enabled new standards in design versatility to be reached, dispensing with the need to choose from a range of sizes and types. With the new technology of the Hydro-Brake OptimumTM from Hydro International engineers have complete flexibility to design each unit for absolute fit and to balance flow rates and surface water storage requirements to suit each drainage project. The result is optimised hydraulic efficiency and a storage saving of up to 15% compared with earlier technology, or alternative devices.

For more information about the new Hydro-Brake OptimumTM call the Hydro-Brake® Hotline on 01275 337937, email enquiries@hydro- or visit http://www.hydro- brake-optimum.

Alex Stephenson Contact Alex by:

email: Telephone: 01275 878371

Industry Knowledge Paul Cobbing

Paul is Chief Executive of the National Flood Forum, a national charity that supports and represents people and communities at risk of flooding. He has worked on many environmental issues throughout his career for public, private and voluntary organisations. The National Flood Forum is now trying to ensure that the needs of people at risk of flooding are at the heart of new policies on insurance.

Flooding and household insurance

With the onset of rain we have moved seamlessly from worries about drought to flooding. The problems of drought still remain and won’t disappear for some months, but the worry of people who have been previously flooded quickly comes back, “When you have watched in disbelief water coming into your house, it’s always at the back of your mind” is a comment I have heard a lot of lately. The key difference between most civil disasters in the UK and flooding is that fire, explosions, industrial accidents, earthquakes, transport trauma, etc., are mainly one off incidents which rarely reoccur in the same locality and their frequency and impact is actively managed and reduced by legislation, planning and investment. Flooding is different. Flooding incidents are increasing decade by decade and climate change and increasing urbanisation are unlikely to reduce this pattern.

Furthermore the probability of a once flooded community being repeatedly affected is real, with the victims of flooding being serially traumatised and their communities blighted. When it rains I suppose, yes, I feel quite depressed. I’d rather just set fire to the house, walk away and just never come back I think. I couldn’t do it again. The result of flooding is often: Incredibly high stress levels • Illness • Anger

• Frustration • Fear

• Loss of faith in those that manage the risk

• Resignation that nothing will happen to improve the situation

• Apathy to those that manage the risk

• Contentious communities Although there have not been huge numbers of homes flooded so far during the latest rains, our advice line has been full of calls from people who are worried; because they can’t

get insurance, can’t get insurance companies to acknowledge that flood defences have been put in place and because their existing insurers have raised their premiums and excesses. We have even had some recent cases where people have been unable to move out of their homes because the purchasers can’t get insurance. We are able to help most people, but are concerned that when the Statement of Principles (the agreement between the government and the insurance industry on covering flood risk in household insurance) we are going to see many more people struggling to get insured.

Getting flooded is traumatic enough, but the prospect of not being able to get insurance is now worrying people. There is a real concern that they will get trapped in their homes, unable to sell, that their mortgages will be invalidated because they can’t get insurance, that the value of their property will fall, and if they do get flooded they won’t be able to afford to reinstate it.

That is why getting a new framework in place quickly is so important, one that the insurance industry can work with and one that the public can rely on. It is particularly important that we protect those who are most vulnerable, those who don’t have the resources to buy themselves out of trouble, as well as the elderly, the disabled and the marginalised. It is also important that it is fair and seen to be fair, not just to individuals, but to communities too. That’s why we are working hard to encourage Government and industry to get the right result; a just and fair approach that protects people’s financial wellbeing, even if the rest of their lives have been turned upside down

Paul Cobbing Contact Paul by: Telephone: 01299 403055


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