Storm drain
From Free net encyclopedia
Image:Curb gutter storm drain.JPG A storm drain, storm sewer, stormwater drain (Australia) or surface water (UK) system is designed to drain excess rain and ground water from an area. Storm drains vary in design from small residential dry wells to large municipal systems. They are present on most motorways, freeways and other busy roads, as well as towns in areas which experience heavy rainfall, flooding and coastal towns which experience regular storms.
Ideally, storm drains should be separate from sanitary sewers, though in some places the runoff from storm drains is subjected to sewage treatment when there is sufficient capacity to spare. In these systems a sudden large rainfall that exceeds sewage treatment capacity will be allowed to overflow directly from the storm drains into watersheds via structures called combined sewer overflows. This happens least in Australia and Canada.
Most drains have a single large exit at their entrance (often covered by a grate to prevent acess by humans and exit by debris) into either a canal, river, lake, resevoir, sea or ocean and spread out into smaller branches as they move up into their catchment area.
Pipes can come in many different shapes (rectangular, square, bread loaf shaped, oval and, more commonly, circle) and have many different features (including waterfalls, stairways, blaconys and pits for catching rubbish or Gross Polutant Traps (GPTs). Several different materials are also used, brick, concrete and even plastic in some cases.
Building codes vary greatly on the handling of storm drain runoff. New developments might be required to construct their own storm drain processing capacity for returning the runoff to the water table and bioswales may be required in sensitive ecological areas to protect the watershed.
An international subculture has grown up around the exploration of stormwater drains. Societies such as the Cave Clan regularly explore the drains underneath cities. This is commonly known as 'urban exploration', but is also known as 'draining' when in specific relation to storm drains.