Three Mills Lock

Three Mills Lock, also known as Prescott Lock, is a lock on the Prescott Channel on the River Lea in London. The current structure was constructed by British Waterways[1] and officially opened on 5 June 2009.

Three Mills Lock
Three Mills Lock
51°31′44″N 0°00′16″W
WaterwayRiver Lee (Bow Back Rivers)
CountyTower Hamlets
Greater London
OperationCanal & River Trust
First built2008–09
Length62 metres (203 ft)
Width8 metres (26.2 ft)
Falltidal
The construction site from Three Mills island.

The lock cuts off a section of the Bow Back Rivers from the tide, creating new opportunities for leisure boats, water taxis, trip boats and floating restaurants. It also allowed barges carrying construction materials to access the sites of the London 2012 Olympics and Stratford City.

Original lock

The original Three Mills Lock was constructed in the 1930s[2] as part of a scheme for flood prevention and the creation of employment.[3] It bypassed the tide mills at Three Mills, and included a sluice structure, which was used to control water levels in the Bow Back Rivers. This structure became inoperative by the mid 1960s, and was removed in the 1980s,[4] by which point the Bow Back Rivers had been classified as "remainder waterways" by the Transport Act 1968, and there was no funding for maintenance.[5] As a consequence of this, the rivers upstream reverted to being tidal. This made navigation difficult, since there was not enough water at low tide, and at high tide, there was insufficient headroom,[6] due to the low level of the Northern Outfall Sewer, which crosses the waterways.

New lock

With the selection of the island formed by the City Mills River and the Lee Navigation as the main site for the 2012 London Olympics, restoration of the Bow Back Rivers was considered an important part of the development,[7] as it would allow construction materials to be delivered by barge.[8]

A new lock and sluice structure was designed for the Prescott Channel, along with the Three Mills Wall River Weir to prevent tidal water flowing backwards through the Three Mills tidal mill.[9] Prior to the development, tidal levels on the Bow Back Rivers reached 15.8 feet (4.8 m) above ordnance datum (AOD) on spring tides. The sluice is designed to stabilise levels at 7.5 feet (2.3 m) AOD, so the lock structure has to cope with levels on the downstream side which might be higher or lower than those on the upstream side.[10]

The new lock is 203 feet (62 m) long, 26 feet (8 m) wide and 7.9 feet (2.4 m) deep, and is able to hold two 350-tonne barges (the present locks on the nearby Lee Navigation limit barges to about 120 tonnes).[11] The tidal range is handled by the use of hydraulic sector gates at both ends of the lock, and the structure incorporates two large rising radial gates for flood control in the Bow Back Rivers.[6]

A site in the river just south of this lock is the resting place of the remains of the Euston Arch.[12][13] A footbridge for pedestrians and a fish pass for migrating fish was incorporated into the design of the lock,[6] and British Waterways planned associated improvements to the navigation and tow path, as a part of the Olympic legacy.

An unexploded 2,200-pound (998 kg) Hermann bomb from World War II was found on 2 June 2008. The bomb was made safe, in a controlled explosion, after five days of disruption to tube and rail services.[14]

Impact

The effect of building the lock, together with the weir at Three Mills, was to lock out the tide just north of the House Mill. This means that this section of the Bow Back Rivers has ceased to be tidal. The lock was constructed so that barges from two large building projects (the London 2012 Olympics and Stratford City) could pass through the lock, taking spoil out and delivering building materials on to the sites, via a new wharf on the Waterworks River.[15] Barges can pass directly into the northern section of Bow Creek to the River Thames. The head of water created by the lock may be used to fill the mill pound and once more allow operation of the Three Mills tidal mill.

The lock officially opened on Friday 5 June 2009,[16] but the expected use of the lock for the construction of the Olympic Park was reportedly much lower than originally planned.[17]

West Ham and Bromley-by-Bow are the nearest London Underground stations. The nearest Docklands Light Railway stations are Bow Church and Pudding Mill Lane

See also

Bibliography
  • Boyes, John; Russell, Ronald (1977). The Canals of Eastern England. David and Charles. ISBN 978-0-7153-7415-3.
  • BW-London (August 2006). "Prescott Channel Water Control Structure" (PDF). British Waterways. Archived from the original (PDF) on 19 February 2012.

References
  1. "Revitalising London's Olympic Waterways". British Waterways). Archived from the original on 10 March 2012. Retrieved 1 August 2008.
  2. BW-London 2006, p. 3
  3. Boyes & Russell 1977, p. 36
  4. BW-London 2006, p. 36
  5. "Bow Back Rivers - A potted history". British Waterways. Archived from the original on 7 February 2012.
  6. "Restoration Plans". British Waterways. Archived from the original on 10 March 2012. Retrieved 27 February 2012.
  7. BW-London 2006, p. 1
  8. BW-London 2006, p. 2
  9. BW-London 2006, p. 46
  10. BW-London 2006, pp. 5–6
  11. Notes and News (April 2007) (Greater London Industrial Archaeology Society)
  12. "Euston Arch found at bottom of river". The Times. 4 June 1994.
  13. "Where are the remains of the arch?". Euston Arch Trust. Archived from the original on 10 February 2010. Retrieved 16 July 2008.
  14. ""Hermann" the German bomb says farewell with a bang—after 67 years". East London Advertiser. 6 June 2008. Archived from the original on 8 April 2009. Retrieved 9 June 2008.
  15. Webster, Ben (11 May 2005). "Canals set to make inroads on routes clogged by lorries". The Times. Retrieved 1 August 2008.
  16. "Waterway revived as Olympic route". BBC News. 5 June 2009.
  17. "London 2012 Olympic Games: Canal barge plans 'failing'". 16 February 2010. Archived from the original on 29 February 2012.
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