They are commonly used for bridge-pier repair or replacement and other underwater works, as well as dam and dyke construction.
Sheet-piled cofferdams may use a cantilever arrangement, where embedment into the ground provides restraint, or a supported or propped arrangement with walers, struts or another appropriately designed restraint. The choice depends on ground and water conditions, loading and excavation depth; neither arrangement is automatically suitable for a given site.
Seepage, dewatering, ground and structural stability, and the engineered temporary-works installation and excavation sequence must be assessed for the project. Timber cofferdams are another example from DAACE’s historical experience, including work near existing services in sandy ground.