SUDs Flashcards
What are SUDs
. Sustainable urban drainage systems
. A sequence of water management practices and facilities designed to drain surface water in a more sustainable approach than what has been the conventional practice of routing run-off through a pipe to a watercourse.
Problems with surface water run off
. Increased downstream flood risk as a result of the run-off from roofs and paved areas
. Rainwater diverted to piped systems reduces the amount of water soaking into the ground, as a result, ground water levels fall and dry weather flows in watercourses are reduced
. Suurface water run-off can lead to poor water quality in rivers and streams, affecting biodiversity + amenity value, after heavy rain through the drainage system is often highly polluting
. Urban watercourses are unattractive
. SUDs can reduce harm to water resources + improve quality of built environments
SUDs aims
Whilst their primary function is to assist with urban drainage SUDS also aim to improve or maintain good environmental quality. Improving people’s perceptions and lived experience of a place.
SUDs example
. Alcester primary care centre
. SUDs used - soakways, swales, raingardens, permeable pairings
. Benefits - environment benefits staff + patiences, control of surface runoff, water treated biologically through the system, biodiversity potential icreases, lower cost of installation
Swales and basins
. Can be created as features within the landscaped areas of the site, or can be incorporated into ornamental, amenity and screen-planted areas where they would be looked after as part of the normal maintenance contract.
. They provide temporary storage for storm water, reduce peak flows to receiving waters and facilitate the filtration of pollutants
. They encourage microbial decomposition and allow water infiltration directly into the ground.
. Installed as part of a drainage network connecting to a wetland, prior to discharge to a natural watercourse.
. May be installed alongside roads to replace conventional kerbs, saving construction costs
Wetland
. Contribute to visual amenity and biodiversity where they include a permanent water body.
. Can be designed to accommodate considerable variations in water levels during storms, thereby enhancing flood-storage capacity.
. The level of solids removal can be significant when enough time for detention is allowed.
. The algae and plants of wetlands provide a good level of filtering and nutrient removal.
. Ponds and wetlands can be fed by swales, filter drains or piped systems, and the use of silt traps will help to manage sedimentation.
Infiltration trenches
. Infiltration trenches are stone-filled reservoirs to which stormwater run-off is directed, and from which the water gradually infiltrates into the ground.
. Their longevity is enhanced by incorporating a filter strip, gully or sump pit to remove excessive solids at the inflow.
. Filter drains have a perforated pipe which carries flow along the trench.
. This enables the storage, filtering and some infiltration of water passing from the source to the discharge point.
. Pollutants are removed by absorption, filtering and microbial decomposition in the surrounding soil.
. Systems can be designed to successfully incorporate both infiltration and filter systems.
Permeable pavements
. The need for surface water drains and off-site sewers can be reduced or where run-off is encouraged to flow through porous pavements
. Depending on the ground conditions, the water may infiltrate directly into the subsoil or be stored in an underground reservoir before slowly soaking into the ground.
. If infiltration is not possible an impermeable membrane can be used with an overflow to keep the pavement free from water in all conditions.
. Pollutant removal occurs either within the surfacing or sub-base material itself, or by the filtering action of the reservoir or subsoil
