A cofferdam is a temporary dike built across a body of water, and constructed to allow the water to be pumped out of the enclosed area. Cofferdams are used in order to allow for a dry working environment.

Under what conditions might you want to use cofferdams?

Cofferdams are commonly used for construction or repair of permanent dams, oil platforms, bridge piers, etc., built within or over water. These cofferdams are usually welded steel structures, with components consisting of sheet piles, wales, and cross braces.

How are cofferdams used during foundation construction?

A cofferdam is a temporary structure designed to keep water and/or soil out of the excavation in which a bridge pier or other structure is built. When construction must take place below the water level, a cofferdam is built to give workers a dry work environment.