Introduction to Sustainable Drainage
Construction projects and new site developments generally create large areas of finished surface which are relatively impermeable; these typically include roads, roofs and car parks.
Conventional piped drainage systems can magnify the risk of flooding associated with large concentrated volumes of runoff generated by a storm event.
The requirement to provide stormwater management systems on new developments is becoming a more common occurrence. Control measures are implemented to ensure compliance with the limited discharge criteria usually enforced as a planning condition.
Sustainable urban Drainage Systems (SuDS) should replicate as closely as possible, the natural drainage from a site before development. Developers have to incorporate an efficient way of controlling stormwater, either by limiting the outflow and providing temporary storage, or where conditions are suitable, providing soakaways for the stormwater to infiltrate back into the surrounding ground.
In undeveloped areas, typically only 5% of rainfall becomes surface water runoff whereas in densely populated urban areas up to 95% of rainfall is treated as surface water runoff, adding extra burden to drainage systems, which are often already at their full capacity.
The SUDS concept is based upon the principle of minimising the impact of a new development on the environment and is now recognised as one of the most effective ways to reduce flooding and its associated pollution risk
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