Expert Solutions for Every Construction Challenge

Sub-ground Dewatering or Wellpointing as it is often called is a method of controlling or lowering the level of groundwater within an aquifer. When Contractors are faced with having to excavate below the existing groundwater 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, depending on ground conditions and initial groundwater level.

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.

To control any surface water or seepage of water between hard impermeable strata, French Drain system proves very efficient. French Drain System involves extracting water through hard strata or draining surface water. The extraction of groundwater can take place by gravity. In case of formations with low permeability we advice to refill the drain trench with gravel. As a result the flow of groundwater to the drains will be improved.

Sump Pumping is considered as the simplest way of Dewatering System. Generally, in dewatering works we are using sump pump to remove the water accumulated in a certain part of the plot excavation. The groundwater is allowed to seep into the excavation, and then collected in sumps and pumped away to the nearest discharge point for disposal. This method can be very effective and economic in well-graded coarse soils (such as gravelly sands, sandy gravels and coarse gravels) or in hard fissured rock.