Northern Stormwater Interceptor, Bristol

Coordinates: 51°27′18″N 2°35′28″W / 51.455°N 2.591°W / 51.455; -2.591 The Northern Storm Water Interceptor (NSWI), is a massive stormwater tunnel that acts as a flood prevention measure for Bristol. Building started in 1951 to relieve flooding over many parts of Bristol, and was completed in 1962. It is some 4-5metres in diameter and runs from the River Frome at Eastville to the Black Rocks Quarry in the Avon Gorge. Originally proposed by the County Surveyors Frederick Ashmead and Col T H Yabbicom in the 1890s, due to the Great War, the Depression and the Second World war, construction was postponed until 1951. The scheme was reborn after the floods in Bristol 1947. The Tunnel was designed by such Bristol City Engineers as Peter Steele and Bernard Smission from 1947. The tunnel was blasted through Limestone, Dolimitic Conglomerate and Keuper Marl and lined with a 375mm thick concrete lining. At its deepest the tunnel is 90 metres deep.

Smission invented the Energy Dissipating Vortex Drop Pipe System of which two were constructed at Clifton Down and Hampton Road. The technology has since been used in Chicago, New York and closer to home in Plymouth.^[1]

References

1. ^ "Bristol City Council: Pollution control - water: Bristol Living Rivers Project - Waterways Monitoring". www.bristol.gov.uk. http://www.bristol.gov.uk/ccm/content/Environment-Planning/Pollution/bristol-living-rivers--watercourses.en%3Bjsessionid=38F780BCD7A16BA5359CFF62EAB9CC54.tcwwwaplaws3?page=4. Retrieved 2009-05-26. 

External links

• Nettleden - The Motherload, Bristol
• "NSI map - Nettleden.com". www.nettleden.com. http://www.nettleden.com/venues/bristol-drains/. Retrieved 2009-09-17.  Map