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Victorian 'dustbin' valves removed from Thirlmere aqueduct
12:21pm Tuesday 23rd October 2012 in News
After more than 100 years of dedicated service to the North West, 85 massive Victorian water valves have been consigned to the scrap heap.
The huge 2.5 tonne "dustbin" valves have been removed from the 96-mile aqueduct which links Manchester to the Thirlmere in the Lake District as part of a £20m project by water company United Utilities.
Engineers say the mammoth operation, which was spread over 18 months, was the equivalent of performing open heart surgery on the huge pipe, because it was all done while it was still in use.
Project coordinator Guy Lovell said: "The Thirlmere aqueduct is important for regional water supplies so we didn’t want to have to shut it down if we could help it. At full capacity the aqueduct can carry up to 250 million litres of water a day. Over the last year and a half we reduced it temporarily to just 170 million litres - but that's still an awful lot of water."
The valves were cutting-edge technology when they were installed by Victorian navvies at the turn of the 20th century.
Their job was to shut the pipe down automatically if it burst.
They do not use any electricity, only natural water pressure and gravity.
In fact the whole aqueduct, from Thirlmere reservoir, near Keswick, to Lostock near Bolton, is powered only by gravity. There are no pumps.
"They are pretty amazing pieces of kit," said project manager Paul Anderton.
"They were fitted in siphon wells where the water enters one of the pressure pipelines. If a leak reduced the water level in the aqueduct, the ball cock would drop and shut off the valve. It's almost the same as what happens in your toilet cistern, but on a much bigger scale.
"Each individual ball cock is made of a spherical hollow copper float measuring almost a metre across. It’s been a huge engineering challenge, especially getting power and access to each site."
The valves have now been replaced with modern valves called penstocks, which are more up-to-date and are electronically linked to United Utilities'network control centre, so they can constantly send back data and be operated remotely if needs be.
Most of the valve metal, including cast iron, copper and brass, has been recycled, yielding money to keep the cost of the project as low as possible.
However the final operating valve will be saved and cleaned up as a historical artefact and put on display in one of the companies' offices.
"The valves have served us and our seven million customers very well for the past 100 years but it's time for them to go. The new penstocks are just what we need for water supply in the 21st century but they don't have the same romance attached to them as their predecessors. It's a fitting tribute to the 3,000 people who built the Thirlmere aqueduct, that we'll be keeping one of them in perpetuity as a reminder of their hard graft and ingenuity," said Guy.