Repairs to Thames Water’s Island Barn reservoir are currently being carried out from pontoons in order to prevent disruption to water supplies and the reservoir’s resident sailing club.
Seepage issues meant that remedial work on the reservoir embankment dam was necessary and this is currently being carried out by Sheet Piling UK using sheet piles.
The reservoir, built by Sir Robert McAlpine, opened in 1911 by the Metropolitan Water Board and stores 4.5bn litres abstracted from the River Thames. The reservoir is impounded by a 2.74km long earth embankment dam with a puddled clay core that extends into the underlying London Clay.
Grouting from the crest and diaphragm wall solutions were considered after a Willowsticks survey mapped groundwater flows that were suspected from wet patches and localised slipping on the embankment face.
“Historically a reservoir like this would be drained for work to be done on its walls, but this would have meant the sailing club finding a temporary new home and also taking the reservoir out of supply, which after a dry winter and spring, we didn’t want to do,” said Thames Water construction manager Amit Chakraborti.
Sheet Piling UK is currently installing 18.3m long piles at three sites with a total linear length of 240m and work is expected to be completed in November.