Innovative air ‘pig’ technology has been used to successfully clean part of the Vyrnwy Aqueduct in Cheshire, marking the first time a water pipeline of this size has been cleaned by this air-propelled, barrel-like device.

The feat of modern engineering was achieved by United Utilities and contractor Avove, who are working on the Vyrnwy Aqueduct modernisation programme, cleaning and relining the three parallel pipelines that carry water from Lake Vyrnwy to customers across the North West.

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. 

Using the device across an 18.6km stretch of the viaduct is set to reduce water usage in the process from 9.4 million litres when compelled with traditional water-propelled 'pigs' to 91,000 litres.

The ‘pig’ has successfully been propelled along the 1m diameter pipes across the first 2.6km section, removing any sediment that has built up from the natural minerals in the water and ensuring that this piece of incredible Victorian engineering continues to supply high-quality drinking water.

John Hilton, Programme Director at United Utilities, said: “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.”

Workers are now busy preparing for the start of relining the other two pipes that make up the aqueduct, with work set to start in the next couple of months.

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. 

Because only 91,000 litres of water will be required rather than 9.4 million litres, only one tanker movement will be required to bring and take away water to propel the pig, instead of 1,400.

Patrick Rafferty, Avove’s business director of operations, said as a team, Avove and United Utilities were bringing innovative ways of working to the forefront of the industry.

"This project is breaking ground in how we approach the inspection, cleaning and relining of three parallel pipelines that carry water underneath Cheshire," he added.

“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.” 

He added Avove’s in-house design and environmental teams identified two key areas for carbon reduction within the phase 1 build sections working and were 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,” he said.

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