Coffer Dam Used At Meath Works

Piling and anchoring contractor Trench Control has installed its first water inflated coffer dam in Co Meath.

The barrier was installed across the River Boyne to provide a safe working environment for Siac Construction, which is installing a diffuser pipe from the new Wastewater Treatment Plant in Donore to the River Boyne.

Due to environmental concerns regarding possible damage to the river bed along the Boyne and the aquatic life within the river, a traditional steel cofferdam could not be used.

After extensive discussions between the Eastern Fisheries Board, Siac and Trench Control, the Water Filled Dam system was agreed as the only solution that would meet the key objectives of safety without permanent damage to the river Boyne.

The barrier is designed to hold back up to 2m of water and is used when steel sheet piles cannot be driven due to ground conditions, lack of access or when it would cause permanent damage to the environment.


The solution for the River Boyne was to provide a tee-pee design with two sides of a triangle attached to the river bank.

This would enable the internal area of the tee-pee to be protected against the flow of water from the Rive Boyne while installation of a pipe diffuser took place. Installation was completed in one day.

Trench Control said the most difficult part of the process was access to the site through a small laneway. This was achieved using a fork lift to site where the excavator was waiting.

Once on site the small excavator was used to position the dam on the river bank and as it was filled with water it was dropped into position.

Once installed, the Water Filled Dam is so heavy that it sits on the river bed forming a dam that diverts the river away from the site. Final checks are made to backfill any small gaps where the Water Filled Dam meets the river bank and dewatering took place.

The pipe diffuser was installed the following day and the dam was removed the day after reducing a complex sheet piling project to a very simple 3 day project.

Due to its success, the system is being reviewed for additional works in Tipperary and Carlow where environmental concerns negate the ability to use traditional methods.

For further information contact Colm Smyth, Marketing Manager, Trench Control, Tel: 086 3603460 or email: colmsmyth@trenchcontrol.ie

(PR/KMcA)