Sustainable Drainage System (SuDS)
In natural environments, rain falls on permeable surfaces and soaks into the ground; a process called through infiltration.
In urban areas where many surfaces are sealed by buildings and paving, natural infiltration is limited. Instead, drainage networks consisting of pipes and culverts, divert surface water to local watercourses. In some cases, this has resulted in downstream flooding and deterioration in river water quality caused when foul sewers are overwhelmed by surface water leading to a release of dirty water into rivers.
Sustainable drainage systems aim to alleviate these problems by storing or re-using surface water at source, by decreasing flow rates to watercourses and by improving water quality.
There is no single type of SuDS and are likely to comprise a series of steps such as collecting water for irrigation, green roofs, vegetated swales (ditches), filter trenches, retention ponds and wetlands, as well as soakaways and permeable paving.
Typically these are shallow systems and will require a holistic approach.
Suitable testing types: BRE365, FHST (for preliminary design), VP (for small soakaways and percolation trenches)