Borehole water is increasingly becoming popular especially in Africa where water shortage is rampant. But do you know how water borehole drilling is done? This article looks at the process of water borehole drilling:
1.Pre-drilling
Water borehole drilling usually starts with a geological survey and vertical electrical sounding. The VES sounding attempts to map the availability of water by taking resistivity measurements using probes at a set distance apart.
Before commencing drilling, you might need a drilling permit and an environmental green light from relevant authorities depending on the rules in your country.
2.Drilling
A drilling rig is required for the drilling. As the drill progresses into the ground, extra drill rods are added until eventually the drill reaches the required depth; 160m (500′) in our case. We employed a geologist to supervise the drilling process; one of the best decisions we made. Once drilled, the bore-hole must be lined with steel casing to stop the bore-hole collapsing and to screen out the large sand particles from entering the pump. The casing is plain in the areas with no water and with fine slots in areas with water.
During drilling, the water layers tend to get blocked by clay and other debris from the drilling. For maximum water yield, the bore-hole must be developed. High pressure water and air are forced down the bore-hole to open up the pores.
After development the bore-hole is given a 24hr test pump to pump out dirty water and to check what yield the bore-hole can supply. In our case, the bore-hole is able to supply 2,800L / hour. Finally, samples are taken for bacteria and chemical analysis.
3.Pumping and piping the borehole
The kind of pumping system and piping installed in your new domestic water borehole will largely depend on the intended use of the borehole water. You may choose mains powered, solar powered and wind powered.
4.Cost of drilling a borehole
Every borehole is unique, because the combination of factors that impact the components and processes used will almost always be different.
This is why borehole drilling cost is not just a number on a paper, but a carefully calculated formula affected by the conditions.
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