Thames Water Ring Main
| Thames Water Ring Main | |
|---|---|
| Overview | |
| Type | Urban water infrastructure |
| Status | Operational; being extended |
| Locale | Greater London |
| Construction Period | 1988 - 2025 |
| Website | http://www.thameswater.co.uk |
| Operation | |
| Operational | 2025 (planned completion) |
| Owner | Thames Water |
| Technical | |
| Tunnel length | 25 km (16 mi) |
| Capacity | 0.3 Gl/d (gigalitre / day) |
| Depth | 10 m (33 ft) – 65 m (213 ft) |
| Tunnel diameter | 2.54 m (8.3 ft) |
| Cost of construction | £250m |
The Thames Water Ring Main (TWRM) (formerly the London Water Ring Main/LWRM) is a major part of London's water supply infrastructure, approximately 80 km (50 mi) of mostly 2.54 m (100 in) concrete pipelines to transfer potable water from water treatment works (WTWs) in the Thames and River Lea catchments for distribution within London.
The initial ring was constructed by Thames Water between 1988 and 1993. Two extensions have been constructed, and there are plans for further extensions through to 2025.
The average daily flow is approximately 0.3 gigalitres (0.3 × 109 litres), out of a London average day demand of approximately 2.0 gigalitres (2.0 × 109 litres). The main currently comprises a major loop linking the Hampton, Walton, Ashford and Kempton WTWs clustered on the Thames upstream of Teddington Weir to central London by a southern branch via Brixton and northern branch via Kew, and a separate unconnected length from Coppermills WTW to Stoke Newington. The main is well below most water mains, at a depth of 10 m (33 ft) to 65 m (213 ft) below ground level and approximately 10 m (33 ft) to 30 m (98 ft) below sea-level. It is connected to water supply zones by some 20 shafts that extend from the main to ground level.
The main serves as a partial alternative transfer system to existing trunk mains suffering increasing frequencies and severities of leaks and bursts. Some of the oldest operational pressure mains in the world (the oldest dates from 1838), the high-level trunks have weakened with steady corrosion, and there has been both an increased carrying requirement resulting from increasing water demand, and increasing external stresses resulting from higher vehicle weights and frequencies. This has been exacerbated by limited system redundancies which has restricted preventative refurbishment. The main has both extended the operational life of the high-level trunks by reducing the flow demands placed on them, and, by providing a high degree of redundancy, enabling key trunks to be isolated and maintained.
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