A method for draining permeable deposits around an excavation that requires small cones of depression. Tubes about 100 mm in diameter, with wire mesh screens, are sunk into the ground and connected by a header pipe to a suction pump at the top. Usually a series of well-points are connected to one header pipe. When these are used in a staged excavation a considerable depth can be drained and the drawdown restricted, because each well-point acts as a hydrogeologic boundary.
Subjects: Earth Sciences and Geography.