Seal Slabs and Underwater Concrete Soles

To construct a watertight excavation pit in conditions where the final excavation level is well below the water table, a watertight concrete seal slab is required in addition to watertight retaining walls, if the water table outside the pit cannot be lowered. If no impermeable soil layer (for example clay) exists at the embedment level of the retaining wall, seal slabs can be made from tremie concrete, jet grouting or using various injection methods. Vertical Ground Anchors will reduce the need for buoyancy control by dead weight.