Dewatering Boreholes

Groundwater is normally a very desirable commodity for most businesses and domestic properties to utilise and reduce their costs.

However, some areas require the removal or control of excess ground water. This is usually the case when construction companies encounter high levels of groundwater preventing the building of foundations or for mining companies who need to control the flooding of water.

An efficiently designed dewatering system allows construction to continue safely below ground in areas where ground water would have otherwise caused delays or problems.

A desktop study is carried out to design a system of boreholes capable of pumping out the ground water at a suitable rate to control its flow and reduce the level of water.

There are two basic types of dewatering methods:

  • Shallow boreholes or well point system.
  • Deep wells system.

A typical wellpoint system consists of a series of small diameters boreholes (wellpoints) connected via a header pipe to the suction end of a specially selected borehole pump. The pump creates a vacuum in the header pipe and draws water up and out of the ground.

Wellpoint dewatering is commonly used for excavations of shallow depths. In optimum ground conditions a wellpoint system can be installed speedily and made operational in a very short time.

A deep well system consists of an array of boreholes pumped by submersible pumps. Pumping the water from each borehole well lowers the groundwater level and creates a drawdown. Several wells acting in combination can lower groundwater level over a wide area beneath an excavation.

This method does not operate on a suction principle therefore large drawdowns can be achieved and this is limited only by the depth of the boreholes and the hydrogeological conditions of the site.

The boreholes are generally located just outside the area of proposed excavation, and are pumped by electric submersible pumps installed near the base of each well.

Waterseekers Well Drilling Services provides a complete dewatering solutions:

  • Design of dewatering systems
  • Well drilling and installation
  • Pumping tests
  • Monitoring systems
  • On-site operation and maintenance

If you have any questions or would like advice on dewatering systems then please contact us.