World first achieved in Cheshire as innovative technology cleans the first section of Vyrnwy Aqueduct

An innovative system has successfully cleaned part of the Vyrnwy Aqueduct in Cheshire, marking the first time, globally, that air ‘pig’ technology has been used to clean a water pipeline of this size.

The achievement has been realised by United Utilities and contractor Avove in the Vyrnwy Aqueduct Modernisation Programme, which is cleaning and relining the three parallel pipelines that carry water from Lake Vyrnwy to customers across the North West.

In a world first, they are using an air-propelled barrel-like device, known as a ‘pig’, through the 1m diameter pipes to remove any sediment that has built up from the natural minerals in the water. These ‘pigs’ are traditionally propelled by water, but by going with an innovative method that uses air instead, the work requires less energy to operate and gives a significant reduction in time, cost, and carbon footprint.

Across the 18.6km stretch being cleaned in the phase between Malpas and Tarporley, the air pig system will bring a reduction of eight days in working time required, and also reduce the number of access pits from 37 to 12. It will also see a reduction in water usage from 9.4 million litres to 91 thousand litres, which means only one tanker movement will be required to bring and take away water to propel the pig, instead of 1,400.

John Hilton, Programme Director at United Utilities, said: “We’re delighted to have completed the first 2.6km section of cleaning the Vyrwny Aqueduct, ensuring that this piece of incredible Victorian engineering continues to supply high-quality drinking water to our customers in Cheshire, Merseyside and across the North West.

“It’s great to see this innovative technology at work and bringing great results from the start, and we look forward to seeing the ‘pig’ progress through the pipes over the coming weeks.

“This change of technique offers a safer and better-quality cleaning method than traditional high-pressure jetting, and offers a host of other benefits for the project too. For example, this work only needs one small tanker as there’s a much lower water requirement, and there’s also a significant reduction in the number of access pits required, which provides a great benefit for local communities as we reduce the areas where we are working.

“We’re also busy preparing for the start of relining the other two pipes that make up the aqueduct that starts in the next couple of months, all of which will support our water network for many years to come.”

United Utilities and Avove group - start of cleaning in Cheshire (1).jpgAvove’s Business Director of Operations, Patrick Rafferty, said: “We are delighted to be working with United Utilities on the Vyrnwy Aqueduct Modernisation Programme. As a team, we are bringing innovative ways of working to the forefront of the industry and this project is breaking ground in how we approach the inspection, cleaning and relining of three parallel pipelines that carry water underneath Cheshire.

“Our teams have mobilised the project to a very high standard and continuously strive to innovate and drive carbon reduction within our design and build aspects of the project. Our in-house design and environmental teams identified two key areas for carbon reduction within the phase 1 build sections working and we are seeing fantastic results with the air pig to date.

“We are exploring potential future use of this solution with the United Utilities team, and are looking forward to completing the remaining sections of line 3 with the air pig, and to starting on the relining of lines 1 and 2.”

The Vyrnwy Aqueduct Modernisation Programme has already involved upgrades to water treatment works and refurbishment of pipes south of Malpas.

Vyrnwy Aqueduct Modernisation Programme