The deep well system consists of a huge number of bored wells in the site area, with submersible pumps excavating the water. Whenever water is pumped out of a well, it causes a dry spot in the well, levelling it out and creating a cone of depression or drawdown around it.
In cohesive and low permeability soils, a surface dewatering method can effectively reduce the groundwater table. Water is piped straight from sumps (ditches) along the toes of the excavation works' slopes. Simply put the suction hose with strainer in the sump, prime it, and release the accumulated water.