kofferdikes

Kofferdikes are temporary watertight enclosures constructed within a body of water to create a dry or near-dry workspace for the construction, repair, or inspection of submerged structures. The term is used in Dutch civil engineering and in English-language guidance to describe the function rather than a single fixed design.

They are formed by driving or assembling barriers such as sheet piles, timber cribs, concrete cofferdams, or modular panels around the work zone. The interior is dewatered with pumps, allowing access and operations on foundations, piers, or underwater components. Access is provided through temporary openings in the barrier or through adjacent wet work platforms.

Typical uses include bridge and quay construction, underwater repairs, dredging support, and inspection of submerged structures. The exact design depends on water depth, soil conditions, duration of work, and the required dryness of the interior. After completion, the cofferdam is drained and removed.

Safety, environmental and engineering considerations include maintaining barrier integrity to prevent uncontrolled inflow, monitoring seepage and stability, and managing disturbed sediments. Modern practice relies on prefabricated barriers, reliable pumping, and careful sequencing to minimize downtime and ecological impact.

See also: cofferdam, dewatering, caisson, underwater construction.