Sustainable urban drainage

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Sustainable urban drainage
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Reducing your surface water drainage charges

• The best way to reduce surface water drainage
  charges is to prevent surface water entering the
  public sewer. This presentation explains ways to
  do that (often described as sustainable urban
  drainage) and covers
• An outline of sustainable urban drainage and its
  benefits
• Permeable surfaces and filter drains
• Infiltration devices
• Basins and ponds

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What is sustainable drainage?

• Sustainable urban drainage systems (SUDS) provide
  a natural approach to managing drainage in and
  around sites.
• SUDS work by slowing and holding back the run-off
  from a site, allowing natural processes to break
  down pollutants. SUDS deal with run-off close to
  the source, rather than transporting it elsewhere
  via the public sewer system.

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Benefits of sustainable drainage systems

• Slow down surface water run-off from your site to
  help reduce the chances of flooding
• Reduce the risk of sewer flooding during heavy
  rain
• Recharge groundwater to help prevent drought
• Provide valuable habitats for wildlife in built
  up areas
• Can create green spaces for people in urban areas
• Can help reduce your surface water drainage
  charges

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Permeable surfaces and filter drains

• Filter drains and permeable surfaces are devices
  that have a volume of permeable material below
  ground to store surface water. Run off flows to
  this storage area via a permeable surface.
  Examples of this are
• Grass
• Reinforced grass
• Gravelled areas
• Solid paving blocks with large vertical holes
  filled with soil or gravel
• Solid paving blocks with gaps between the
  individual units
• Porous paving blocks with a system of voids
  within the unit
• Continuous surfaces with an inbuilt system of
  cavities

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Car park drainage does not have to go to sewer

• Infiltration is where surface water is directed
  via cavities within areas of solid paving
• With a porous surface water is drained directly
  through the surface

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Infiltration devices

• Infiltration devices drain water directly into
  the ground. They may be used at source or the run
  off can be conveyed in a pipe or swale to the
  infiltration area. They include soakaways,
  infiltration trenches and infiltration basins as
  well as swales, filter drains and ponds.
  Infiltration devices can be integrated into and
  form part of landscaped areas.
• Soakaways and infiltration trenches are
  completely below ground, so water should not
  appear on the surface. Infiltration basins and
  swales for infiltration store water on the ground
  surface, but are dry except in periods of heavy
  rainfall.

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Infiltration devices (continued)
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Basins and ponds how they work

• Basins are areas for storage of surface runoff
  that are free from water during dry weather
  conditions. These structures include
• Flood plains
• Detention basins
• Extended detention basins
• Ponds contain water in dry weather and are
  designed to hold more when it rains. They
  include
• Balancing and attenuation ponds
• Flood storage reservoirs
• Lagoons
• Retention ponds
• Wetlands

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Basins and ponds

• Basins and ponds store water at the ground
  surface, either as temporary flooding of dry
  basins and flood plains, or permanent ponds.
  These structures can be designed to manage water
  quantity and quality.