Wellpoints are essentially shallow abstraction wells which offer an economical and effective method of groundwater control for site dewatering.
Well points are essentially shallow wells which offer an economical and effective method of groundwater control for site dewatering.
Well points have the advantage of being able to be installed in most ground conditions as well as being easy to maintain. They are particularly suited to control of groundwater levels for shallow foundations and trench works in water-bearing granular soils.
When installed at close spacing at appropriate depths this will lead to satisfactory dewatering and ground stabilisation in stratified and fine graded soils, allowing for safe excavation of the working area on site.
They are effective for excavations up to seven metres deep for a single stage system. For greater depths, if space permits, multi-stage systems can be installed to achieve even greater draw down.
Well points are installed using conventional jetting methods, which involve pumping water at high pressure (supplied by a jetting pump and/or compressed air) through a steel placing tube suspended by a 360° excavator.
If self-jetting wellpoints are used, high pressure water is pumped directly down the riser.
We also have a unique well pointing installation machine which is based upon a small 360° machine with a specialist made wellpoint arm. This makes for economical installation through potentially difficult ground conditions, such as an over layer of clay over confined sand layers.
Once installed, individual wellpoints are coupled by flexible swings to a horizontal vacuum header (collection) main. In turn, the header main is connected to a 100mm/150mm centrifugal or piston vacuum pump.
Abstracted groundwater is then pumped along a pipeline to be discharged via a settlement tank to a suitable point.
For more information on well pointing, please contact Stuart Well Services.