Wellpoint Dewatering

Welltech’s highly skilled personnel have many years experience in this difficult art of managing groundwater.  You can be assured that if you have Welltech on site your project is in good, capable hands.

Wellpoint Dewatering is used in all types of ground which are permeable because of porosity such as gravel, sand, silt and clay.

A wellpoint system consists basically of a series of small wells installed around the perimeter of the area in which the water table is to be lowered and connected to a high vacuum pump by means of a set of header pipes with couplings and fittings.

The system is based on the induced flow of water in the water bearing strata towards filters (wellpoints) kept under vacuum by a high vacuum pump.

The pressure difference created between the pressure of the ground water (atmospheric pressure) and the filters (wellpoints) directs the ground water flow towards the wellpoints at a velocity which depends on the permeability of the various types of ground.

When the wellpoint system in a given section pumps more water than filters through the voids, the water table begins to lower forming a conical surface.

As pumping continues, the dewatered area increases until the capacity removed by the wellpoint system is equal to the capacity due to filtration.  At this point the water table stabilises forming the “cone of influence”.

Naturally, the size of this cone is closely linked to the permeability of the ground and will therefore be larger in low permeability ground.

For more information on the suitability of dewatering for your site, contact David Henderson at any time.