For the construction of the 16.2 km long Liefkenshoek rail link, two single-track tunnels were bored undercrossing the river Scheldt and the B1-B2 Canal Dock. Once they have passed the Scheldt, the tunnels go upward towards the arrival shaft, passing closely underneath the bottom of the Canal Dock. The soil burden above the tunnel, consisting mainly of silt deposits, would only be 4,4 m thick, which could not provide sufficient resistance.

Sheet pile wall excavation pit

The original design had foreseen to dredge 8 m of the silt and replace it with 138,000 m³ of compacted sand and a 26,000 m³ concrete deck on top of it. The compaction of the underwater sand layer to 17 MPa would have needed a 4 m thick temporary sand ballast, which would have reduced the dock's draft by 2 m for a period of at least 6 months.

The main contractor Locobouw consortium designed an alternative solution using a 270 m long and 32 m wide sheet pile wall excavation pit. Between the sheet pile walls, 42,500 m³ of silt was dredged and replaced with 26,000 m³ of low-strength mortar (≤ 5 MPa) and a 16,500 m³ slab of steel fibre-reinforced concrete.