When planning construction pits below the groundwater level, one distinguishes between sealed (watertight) pits and construction pits with a groundwater drawdown.
In the case of a watertight construction pit, the groundwater is pumped out of the excavation pit only. This requires a construction which consists of walls and a base with a very low permeability which form an almost impermeable trough. An artificial base must be created if the subsoil does not naturally provide a full faced low permeable soil layer of sufficient thickness.
Construction pits with a planned groundwater drawdown do not have special requirements on water tightness of the walls and base. Using often multiple wells, the groundwater is usually lowered down to about 0.5 m below the final excavation level.
GuD provides for all engineering services regarding the construction pit; i.e. beginning with site investigation, the planning for all design phases, the tendering process up to the site supervision.