• Description: Val de la Mare Dam;
  • Challenge: The first time the reservoir has ever been partially drained and the project had a very tight schedule as the reservoir needed to be refilled as soon as possible


First constructed in 1962, the Val de la Mare dam in Jersey holds back 900 million litres of water, making it the second largest reservoir on the island. The concrete on the dam is suffering from an alkali aggregate reaction and this created the need for the inside face to be covered with a heavy-duty waterproof membrane to re-seal the dam. This will prolong the life of the dam for many years, but required the reservoir to be drained so that the inside face could be accessed.

SGB designed and installed a unique combination of suspended access platforms and a load bearing support gantry system (constructed from MkII shoring soldiers and scaffolding materials) to provide access to the entire inside face of the dam so that vital maintenance work could be completed. Access to the façade had to be from the walkway on top of the dam wall which was very narrow. This had to remain clear throughout the project to allow the waterproof membrane to be positioned and unrolled down the inner façade. This was achieved by designing a walk-though, ‘tunnel-like’ support structure from scaffolding and shoring MkII Soldier materials. The arrangement of access platforms and egress to the top of the dam’s façade allowed both the team of membrane installers and concrete repair specialists complete access to the façade.