   #copyright

London sewerage system

2007 Schools Wikipedia Selection. Related subjects: Engineering

   The new Abbey Mills Pumping Station
   Enlarge
   The new Abbey Mills Pumping Station
   The original Abbey Mills pumping station
   Enlarge
   The original Abbey Mills pumping station

   In the early 19th century the River Thames was practically an open
   sewer, with disastrous consequences for public health in London,
   including a seemingly endless sequence of cholera epidemics. Proposals
   to modernise the system had been put forward in 1856 but were shelved
   due to lack of funds, but after The Great Stink of 1858, Parliament
   realised the urgency of the problem and resolved to create a modern
   sewerage system.

   Joseph Bazalgette, a civil engineer and Chief Engineer of the
   Metropolitan Board of Works, was given responsibility for the work. He
   designed an extensive underground sewerage system that diverted waste
   to the Thames Estuary downstream of the main centre of population. Six
   main interceptory sewers, totalling almost 100 miles (160 km) in
   length, were constructed, some incorporating stretches of London's
   'lost' rivers. Three of these sewers were north of the river, the
   southernmost, low-level one being incorporated in the Thames
   Embankment. The Embankment also allowed new roads to reduce traffic
   congestion, new public gardens, and the Circle Line of the London
   Underground.

   The interceptory sewers, constructed between 1859 and 1865, were fed by
   450 miles (720 km) of main sewers that, in turn, conveyed the contents
   of some 13,000 miles (21,000 km) of smaller local sewers. Construction
   of the interceptory system required 318 million bricks, 880,000 cubic
   yards (670,000 m³) of concrete and mortar, and excavation of over 3.5
   million tonnes of earth.

   Gravity was used to allow the sewage to flow eastwards, but in places
   (e.g. Chelsea, Deptford and Abbey Mills) pumping stations were built to
   raise the water and provide sufficient flow. Sewers north of the Thames
   feed into the Northern Outfall Sewer, which feeds into a major
   treatment works at Beckton. South of the river, the Southern Outfall
   Sewer extends to a similar facility at Crossness.

   In the 20th century major improvements were made to the sewerage
   system, to reduce pollution of the Thames Estuary and the North Sea.

   The system plays a large part in English writer Neil Gaiman's 1996
   novel Neverwhere. It also featured as one of the Seven Wonders of the
   Industrial World in the BBC television series of the same name.

   The Victorian pipes now amount to less than 1% of the total sewage
   network in London. The original system was designed to cope with up to
   6.5mm (1/4”) of rain falling in its catchment’s area . The London it
   was designed for had a lot smaller population than today’s population .
   The consequences of the continued growth of London meant that the
   carrying capacity of the sewage system that was built in the past has
   been put under pressure. When there is a storm with a high level of
   rainfall (in excess of 6mm),in a short period of time, London’s sewers
   are unable to cope with the large amount of rainwater entering the
   system and the capacity of the treatment stations is overwhelmed by the
   sheer volume of water. The rainwater mixes with foul sewage in combined
   sewers and, when the treatment system cannot cope, Thames Water
   discharges the excess mixed water into the Thames. If this does not
   happen fast enough, localised flooding occurs (surcharge). This can
   mean that areas of streets can become flooded with a mixture of water
   and sewage, causing a health risk. The need for increasing the carrying
   capacity of London’s sewer system has been debated for a number of
   years. However, since the cost of upgrading the sewage system’s
   infrastructure to cope with revised estimates of needed capacity is
   huge, the question of who bears the cost is at the forefront.
   Retrieved from " http://en.wikipedia.org/wiki/London_sewerage_system"
   This reference article is mainly selected from the English Wikipedia
   with only minor checks and changes (see www.wikipedia.org for details
   of authors and sources) and is available under the GNU Free
   Documentation License. See also our Disclaimer.
