We generally use Wellpoint or Sandpoint or Spearpoint Dewatering in a shallow excavation. A
Wellpoint / Sandpoint system constitutes of multiple, closely placed, small diameter pipes with screens
at the bottom. These multiple pipes are connected to a single pump on the suction side which draws
water out of the ground and lowers groundwater table. (Refer figure 1). This method has been used for
over 100 years in the construction industry.

The pump creates vacuum and sucks the groundwater from the surrounding ground through the
wellpoint screens. On the discharge side the pump forces the water through the discharge main for
ultimate disposal.

Depending on the geometry, depth of the excavation, there is a range of different wellpoint
arrangements that can be used. The amount of lowering that can be achieved by a wellpoint (or shallow
well) system is limited by the physical constraints of suction lift. It also depends on the efficiency of the
water/air separation device on the pump, the vacuum efficiency, geological structure, permeability of
the soil mass, width of the excavation and various other factors. Where the land area available for construction is not constrained, the wellpoint system can be used for deeper excavations by means of a multi-stage wellpoint installation.