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Borehole construction
Artesian boreholes


A typical well head


 Borehole construction

Boreholes are drilled to allow us to extract water
generally this water will require a certain amount of treatment before it is fit for drinking
the pictures further down the page are of a borehole that is so clean it requires very little treatment. Many boreholes will require treatment using filters, settling tanks, chlorination & pH correction

Borehole construction

In its simplest form the construction will go something as described below
A hole is drilled into the ground generally with a diameter of at least 300 mm
A lining is inserted into the hole & the lower part of the lining where the water intake is situated is packed with gravel.
The gravel acts as a type of filter media & also prevents sand from being sucked into the well when the pump is running.
The upper part of the well is packed with grout to seal the outside of the borehole shaft & to pack the well.
Finally a concrete slab is added to the top of the well to prevent ingress of pollutants & seal the well head.
A borehole pump will be lowered into the hole on a steel or cast pipe, Alternativly & now more commonly a pump will be attached to a Wellmaster pipe.
Wellmaster pipe is flexible (like a very thick hosepipe) & is easier & quicker to remove if the pump needs replacing.

The Pictures below show a borehole being lifted (left) please notice the solid pipe that fits into the borehole lining the picture on the right shows the pump.
You will also notice the amount of water coming from the well head this is because this borehole is artesian please see below for details on artesian wells



Artesian flow is created because the borehole is drilled at a lower level than the underground rivers from which we extract our water.
The well shown in the
picture above is capable of delivering in excess of  50 litres per second without a pump.




The picture below shows wells pumping into a settling tank prior to filtration
chlorine is injected as the water enters the tank to kill any undesirable elements
Click her for pictures of a typical well head