velpunkt

Velpunkt is a term used in civil engineering to describe a dewatering system that uses an array of shallow, small-diameter wells, known as wellpoints, connected to a common suction header. The arrangement is installed around or beneath a work area to lower the groundwater table, enabling excavation, trenching, or tunneling in water-bearing soils. Water drawn by the wellpoints is collected in the header pipe and pumped away to a sump or drainage system.

Typical components include individual wellpoints with screened tips, short risers, a perforated or screened collector header, a pump (often centrifugal or submersible), and discharge piping to an appropriate disposal or recharge location. The number of wellpoints, their spacing, and the pumping rate depend on soil permeability, groundwater conditions, and the required drawdown.

Operation involves driving or boring in the wellpoints, connecting them to the header, and starting the pump to create suction. Drawdown is monitored to ensure the water level remains below the target depth. Debris and sediments are managed by filters and periodic maintenance, and in some cases treatment is needed before discharge.

Velpunkt systems are commonly used in sandy or silty soils where permeability supports flow between the wellpoints; they are less effective in dense clays or fractured rock. They offer rapid setup, flexibility, and relatively low operating costs compared with deeper groundwater pumping, but require electricity, adequate pumping capacity, and management of runoff.

See also: wellpoint, dewatering, groundwater management.