More about Sustainable Drainage
According to the NHBC Sustainable Drainage systems or SUDS “are a sequence of management practices, control structures and strategies designed to efficiently and sustainably drain surface water, while minimising pollution and managing the impact on water quality of local water bodies.”There are a number of SUDS techniques and the particular combination of techniques employed on any one development depends on the local conditions at any site. A summary of the techniques that could be employed include:
- Green roofing or rain/grey water harvesting techniques;
- Swales – grassed depressions which lead surface water overland from the drained surface to a storage or discharge system, typically using the green space of a roadside margin;
- Basins – designed to hold back storm runoff for a few hours and to allow the settlement of solids;
- Infiltration trenches – shallow, excavated trenches, filled with stone to create an underground reservoir;
- Permeable pavements – permeable concrete blocks, crushed stone or porous asphalt;
- Filter drains – is a trench covered with gravel or rock that redirects surface and groundwater away from an area. They have perforated hollow pipes along the bottom to quickly vent water that seeps down through the upper gravel or rock; and
- Ponds or wetlands – which can be designed to cope with variations in water levels during storms, or prolonged periods of wet weather thereby enhancing flood-storage capacity.
Infiltration Trench
In line with NHBC best practice, the adoption and success of SUDS will depend on the local ground conditions (primarily type of soil) and depth to groundwater in the area. A survey of the ground conditions will be necessary before deciding on a specific SUDS technique. The assessment should also include a study of the ecological status and sediment releases of the area, the possible impacts caused by flooding, and current drainage patterns in the area.
