Additional Benefits of Sustainable Drainage Systems (SuDS)
Our towns and cities are becoming more densely populated. In the UK we are told that the number of homes which must be built every year is more than 200,000. Developments are stretching out into the floodplains and greenbelt, and as we surface over the land, we reduce its natural ability to infiltrate surface water. With more extreme, hotter and wetter weather predicted as a result of climate change, SuDS are playing a much larger part in the management of surface water runoff.
As a result of large scale flooding in 2007 The Pitt Review was published in 2008, focusing on flood risk management. To implement the recommendations from the report, the Flood and Water Management Act 2010 was introduced, although some recommendations took several years to be enforced.
Since April 2015 it has been mandatory for all major developments to include SuDS in planning applications unless they are demonstrated to be inappropriate. SuDS are already having positive impacts on the way we drain our towns and cities by allowing water to;-
- Be retained for longer at source, which can ease the demand on traditional drainage systems
- Infiltrate into the ground using more natural techniques.
By employing or mimicking the slower infiltration rates of natural processes, SuDS aim to slow down the rate at which surface water enters our drainage systems and rivers.
SuDS will play an ever larger role in the management of surface water runoff but there are also lots of added benefits that can be gained from their implementation too. SuDS options may include:
- Permeable paving
Promotes infiltration and can prevent puddling on large areas. It allows water to seep through gaps between blocks or through porous material to the free draining sub base below. Sympathetic design can also result in a much more aesthetically pleasing finish than concrete or tarmac.
- Swales and Detention Basins
Can store large volumes of water when required and allow slower infiltration and evaporation. They may contain no surface water for lengthy periods of dry weather and as a result provide green space which can enhance the biodiversity and public amenity of an area.
- Ponds and Wetlands
Vegetated SuDS can store large amounts of runoff allowing sediment and pollutants to settle or be trapped and broken down by plants and bacteria. This technique also provides habitat for wildlife and amenity for residents of estates and business developments. Wetlands can also improve air quality, absorbing and removing pollution.
SuDS can decrease flow rates and also improve water quality before it makes its way into our rivers by trapping silt, sediment and pollutants.
Surface water runoff can contain:-
- Oils, petrol, hydrocarbons and metals which are released by vehicles onto the road.
- Fertilizers, pesticides and slurry from agricultural runoff.
- Industrial chemicals and other pollutants which may be contained in fly tipping or chemical leaks.
By implementing SuDS to better manage surface water issues, we can also gain the additional benefits of improved water quality along with more diverse green spaces for communities to enjoy and wildlife to inhabit.