Taking a balanced approach to Sustainable Drainage SystemsFollowing the wettest, most prolonged winter on record and some of the most devastating floods in history, there is now an even greater need for surface water run-off to be controlled in a manner which avoids using the overloaded sewer system and is more sustainable in the long term. The Sustainable Drainage Systems (SuDS) approach to drainage includes a wide range of methods, both engineered and landscaped, but there is no one single drainage solution for anyone site. In the majority of cases, a combination of techniques results in best practice explains George Gray, Product Manager at Wavin.

The more we urbanise our landscape, the more we reduce the amount of land that rainfall is able to soak away into the ground. SuDS are designed to drain surface water in a manner that will provide a more sustainable approach and avoid the conventional and more expensive practice of just routing run-off through a pipe to a watercourse.

The numerous characteristics of a site mean that certain sustainable drainage functions may be more appropriate than others. The variety of SuDS components and design options available allows designers and planners to consider local land use, future scenarios, and the needs of local people when undertaking the drainage design.

There are a number of options from natural above ground SuDS solutions including swales, detention ponds, basins and permeable surfaces to engineered solutions such as concrete culverts, plastic pipes, attenuation tanks and soakaways.

With an increased focus on SuDS compliance, there has been a sharp increase in the use of geocellular stormwater management units to create underground structures for infiltration or the temporary storage of stormwater. AquaCell from Wavin is a tried and tested modular technique for managing excessive rainfall and is proven as one of the most effective ways of recharging local groundwater.

“The modular nature of AquaCell makes it perfect for dealing with any given requirement, from just a few units acting as a soakaway, to thousands of units creating a vast underground reservoir,” explains George Gray. “It’s also suited to areas subject to regular and heavy traffic loading such as car parks.”

A high-strength, factory-engineered, geocellular stormwater management unit can be constructed to accommodate calculated run off volumes, thus providing greater assurances to developers, authorities adopting the drainage systems, home owners and insurers alike. The fact that these tanks are buried allows the land above them to be used to create amenity and biodiversity. This potential for land use above these systems is far safer and more valuable to many in society in terms of amenity than large ponds or basins.

“The ideal SuDS scenario is about managing the amenity value and creating a happy medium between the landscaped and engineered solutions,” adds George Gray. “In the case of engineered solutions such as AquaCell, the shape of the tank can be irregular to maximise the land available. The house builder calculates the amount of storage required, depending on site conditions and whether they are working to a one in 30 or one in 100 year rainfall event or even greater”

Continuing urban development, a changing climate and intensive rainfall has meant rainwater is an issue that just won’t dry up without investment and planning. As part of the total solution, geocellular units can work in association with traditional SuDS solutions to provide the most effective flood protection possible for the long term.