Sub-ground Dewatering or Wellpointing as it is often called is a method of controlling or lowering the level of sub ground water within an aquifer.
When Contractors are faced with having to excavate below the existing sub ground water level into the aquifer the simplest and most cost effective method would be to deploy a Wellpoint system.

Wellpoint systems are very effective in a wide range of soils from fine silty sand to

coarse gravels, single stage Wellpoint systems are used to a maximum depth of 4.0 metres.
For deeper excavations twin stage Wellpoint systems can be deployed.

Greater excavation depths or drawdown levels and the ability to overcome the limited suction lift of wellpoints can be made by the installation of Deepwell Dewatering System. Deepwells are also advantageous where there is limited space to install wellpoints close to an excavation, as Deep Wells can be located at a distance to generate required drawdown. Design of Deepwell Dewatering System is more complex than for Wellpoint schemes. Principally, because of the remote locations, Deepwells rely on the interaction of individual drawdown profiles, to produce the desired total drawdown.

Typically, the spacing of Deep Wells is between 10m to 50m. The terminal depth of a Deepwell is dependent on the required

individual well yield and the drawdown profile. This in turn is a function of soil permeability and characteristics, target drawdown’s and spatial parameters.

To control any surface water or seepage of water between the cavities of hard impermeable strata, French Drain system proves very efficient.

French Drain System involves extracting water through cavities of hard strata or draining surface water. The extraction of

groundwater can take place by gravity or vacuum. In case of formations with low permeabilitywe advice to refill the drain trench with drainage sand or gravel. As a result the flow of groundwater to the drains will be improved.