Ice pigging

Our supply pipes are vulnerable to the slow build up of sediment and the coating of minerals in the water. These are harmless to our health but can provide discolouration and odour issues in the tap water.

For years proven traditional methods for cleaning pipes and removing built up sediment have included the use of solid plugs, foam swabbing and air scouring, all of which help clean out the pipes from the inside and remove build-ups that have occurred over time.

However, these traditional mechanical approaches have similar drawbacks; they are costly, cause disruptions and cannot negotiate obstacles such as pumps or junctions in the piping. As the internal workings of pipes become more complicated it becomes harder to operate and amplifies the drawbacks.

Bristol University were keen to trial a new idea that they believed offered a solution to these problems which both Wessex Water and Bristol Water were keen to support.

The technique they suggested involved crushed ice being flushed into a pipe where it forms a soft but abrasive plug. The plug is then pushed along creating a scouring effect that cleans and separates waste from the inside of the pipe with the adaptable shape of the ice allowing it to navigate complex pipework with ease.

This pioneering approach was first trialled in one of our raw water mains near Devizes which contained an interior iron coating. The ice slurry was injected into the pipe through a hydrant and along the length of the trial section. This was repeated until most of the iron had been cleared. Before and after cross sections of the pipe showed how effective this approach had been.

This approach has now been implemented as part of our maintenance operations and is currently being used in our Clean and Clear scheme in Bridgwater. The scheme will help improve 27km of water mains while avoiding any major disruptions to the 34,000 residents dependent on these pipes.