A North East water company is giving discoloured water a frosty reception as it leads the way nationally by using ice to clean the inside of pipes.
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Northumbrian Water is investing £66 million to clean 400 kilometres of trunk water mains, which are large pipes, ranging between 12 and 49 inches in diameter. They transport water around the region’s vast 16,965 kilometre water network, and smaller diameter pipes feed off trunk water mains to supply homes and businesses across the region.
Over time a harmless sediment can build up and stick to the inside walls of trunk water mains. When it is disturbed this sediment can cause discoloured water. The mains cleaning programme, which will improve tap water quality for
one million people, is taking the ‘source to tap’ approach.
Graham Neave, Northumbrian Water’s Operations Director, explains: "The fact that we are currently trialling the use of ice to clean trunk water mains is testament to our commitment to the use of innovative technology and to providing our customers with an excellent quality product. This is the most comprehensive trial of the ice pigging technique that has been carried out in the UK.
"Using ice is much quicker as we don’t have to empty the section of pipe we are cleaning, and refill it, as with other cleaning methods. The holes we dig to access water pipes, to enable the cleaning, are much smaller. Both of these benefits result in less disruption to our customers.
"It usually takes us up to three weeks to clean a two-kilometre section of pipe using ‘pressure jetting’, it takes just a few hours to clean the same amount of pipe using ice. As well as being more cost effective, the process also uses less water than other types of cleaning so it is more environmentally friendly."
A section of pipe is isolated by turning off valves at each end of the length of main to be cleaned. A bit of water is emptied out to make room for slushy ice which is injected into the pipe. The valves are then reopened enabling the water to start flowing again. The pressure of water on either side of the slush compacts the ice and it scrapes the sediment off the pipe walls. The dirty ice is then flushed from the water main and the water is sampled and put back into supply.
Mr Neave continued: "The trial that we carried out this week involved inserting 25,000 litres of ice into the network, at minus seven degrees, and we cleaned a two kilometre section of pipe between Pegswood, near Morpeth, and Ashington.
"We are very pleased with the results of the trial and this will hopefully revolutionise the way we clean our trunk water mains in the future. We hope to be able to clean around 75 kilometres of pipe using this method, as part of ‘The Main Event’."
Matthew Stephenson, Operations Director for Aqualogy, the Bristol-based company that developed ice pigging, explained how the process evolved: "We developed this patented technique for the water industry in collaboration with the university of Bristol. It’s a technique that was originally pioneered for the food industry, but our experience in the water industry has allowed us to scale the process up over the last five years so that we can now offer the benefits of cleaning with ice to water companies.
"The amounts of ice involved are huge, so producing and delivering the right volume in the right consistency has been the main challenge in transferring this new innovation to the water industry, but the results and benefits are just as compelling."
The technique chosen to clean pipes depends on what the pipe and its lining is made of, its diameter and whether it is in a rural or urban location. Cleaning methods used to remove sediment from the inside wall of pipes, include using a giant sponge, spring-loaded metal scrapers or, the most frequently used, high pressured jets of water.
Mike Harrison, Executive Director, Morrison Utility Services, said: "We are delighted, as the main contractor, to undertake this service on behalf of Northumbrian Water following a successful trial period. Our aim is always to introduce innovative and effective new solutions to our clients and this process compares very favourably against more traditional network cleaning methods, generating significant efficiency savings and reducing customer disruption and supply interruptions as enabling works are rarely required."
The first phase of mains cleaning work began in 2007 and the inside of 171 kilometres of pipe was cleaned in South East Northumberland, North Tyneside and the north of Newcastle.
The second phase, branded as ‘The Main Event’, which is underway and due to be complete early 2015, will involve cleaning 218 kilometres of water main in parts of the lower Tyne Valley, Newcastle, North Tyneside and Gateshead. The water company has 2,000 kilometres of trunk water mains.
The majority of cleaning work carried out by Northumbrian Water, so far, has been done by using pressure jetting. A section of pipe is isolated, emptied and cleaned by a machine that travels through the pipe and sprays high pressure jets of water on the inside pipe walls, removing sediment. The pipe is then flushed, disinfected, re-filled and put back into service after a range of water quality samples are taken.
Northumbrian Water are currently cleaning trunk water mains in the Newburn, Leamington and Scotswood areas and are soon to begin cleaning 22.5km of pipe between Newburn Bridge and Gateshead. Cleaning of the first 2km section of this pipe, which is between Newburn Bridge and Stella, will hopefully begin at the end of February.
For further information contact Cara Charlton on 0191 301 6720.