This page contains a Flash digital edition of a book. Drainage Systems ......... It’s time to bust some myths

sustainable outcomes across the land. With such a varying picture still ‘on the ground’, there is real cause for concern. Even before they were officially published, worries about a potential ‘loophole’ in the standards caused ripples across the industry. Concerns among developers about the potential extra costs of installing SuDS were probably behind a late addition of a clause to exempt developers from installing SuDS schemes on th-e grounds of “disproportionate cost”. In my view, this is an unhelpful and unnecessary addition. By applying SuDS principles – as outlined in the standards - and the full toolbox of SuDS techniques, there should be very few schemes that would fall through the net. If this clause really does deliver a ‘get out of SuDS free card’ for ill-informed developers – or even local authorities – it could compromise the whole spirit of the Act.

The perception amongst developers and contractors that SuDS are more expensive to install is one of a number of ‘urban myths’ that have grown up around SuDS. It’s up to our industry to dispel those myths and ensure Local Authorities are fully educated and skilled for their task head.

Another myth which still abides is that SuDS are only ‘green’ or ‘soft’ features. As many of us now realise, this is not true. In fact, SuDS comprise a treatment train which can be selected from a broad range of engineered and more ‘natural’ components. This is the principle of Engineering Nature’s Way, which I believe offers a practical, achievable and clearly-understandable way forward.

Another is that when designing SuDS, one proprietary product is a good as the next one – no matter what is specified on the

drawing. Now that all SuDS schemes are subject to approval by the SAB on the basis of a submitted engineering design, this is a dangerous assumption. If a contractor changes from a specified product, it could change the engineering performance on the site with potentially disastrous consequences. Changing from the specified flow control device, for example, could increase the flood storage capacity required. At best, this would be unprofessional, and at worst, could lead to a costly call-back to site following a flood. This is something that consulting engineers must make clear, and contractors must abide by. The Standards introduce a new requirement for treatment of surface water to remove silts, sediments and pollutants. The stated need for three or four levels of treatment may set alarm bells ringing as contractors contemplate the earthworks involved in ponds, reed beds, swales and basins – not to mention the land take that could otherwise be used for development. Compact treatment devices such as the Hydro Downstream Defender® can provide the answer, by using vortex separation technologies to provide a low- maintenance, no-power solution incorporating several treatment levels in one.

The Standards have also laid out strict requirements for designing stormwater storage and controlling discharges to achieve pre-development or greenfield conditions. To do this economically may often require the use of vortex flow controls such as the Hydro-Brake® Flow Control. These can be used either singly, or in combination, to reduce the storage requirements significantly and consequently the overall project costs.

For more information on Hydro’s stormwater treatment products:

Call 01275 878271, email or visit

Visit Hydro’s SuDS knowledge-sharing website for more news, briefing and comment on the National Standards.


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