Cofferdams Using interlocking steel sheet piles to form a safe, dry working enclosure for construction works to take place

A sheet pile cofferdam forms an enclosure that holds back soil and controls water so construction can take place within an excavation. Typical uses include underground tanks, drainage works, bridge supports, piers and abutments. Interlocking steel sheet piles form the wall, with the support and water-control arrangements designed for the ground conditions and the work inside.

They can be either. A temporary cofferdam supports construction and is removed once the permanent works and site conditions allow. In other schemes, the sheet piles remain as part of the permanent structure. The intended use and duration influence the design, pile specification and the arrangements for installation and, where required, extraction.

No. Some shallow cofferdams in suitable ground can be designed as cantilever walls, relying on the embedded length of the piles for support. Deeper excavations or more demanding ground and loading conditions may need waling beams, internal props or anchors. The designer determines the support arrangement and the stages at which it must be installed.

The sheet pile wall limits water entering the enclosure, and clutch sealants such as WADIT can improve the water resistance of the interlocking joints. The design must also consider groundwater and possible seepage beneath the wall, together with any pumping requirements. A dry working area depends on the complete water-control arrangement, not just the sheet piles.

Yes. Once the works are complete and extraction is permitted by the agreed sequence, temporary sheet piles can be removed, cleaned and returned to stock for future projects. Reuse depends on their condition and suitability for the next scheme. Ivor King provides design, supply, installation and extraction as part of its cofferdam service.

The design team needs the proposed excavation depth and layout, ground investigation and water levels, together with details of nearby structures and loads. Access, working space, the construction programme and whether the piles will be temporary or permanent also matter. These details help determine the enclosure shape, pile lengths, support system and installation sequence.