The Water Borehole Drilling Process

The development of groundwater resources generally takes place in three phases: exploration, evaluation and finally the exploitation of your resources.
In order to manage your groundwater, you need to establish where it can be found on your plot and how much you have. Information can be derived from geological and hydrogeological maps of the area, as well as from aerial photographs, satellite images and local rainfall figures. The information on existing boreholes in the area will be important, including their sites, yields, depths at which water was intersected and water quality.
Geophysical surveys of your smallholding can be undertaken by qualified geohydrologists, using methods appropriate for the geological conditions on the site. Most methods are non-invasive and can include electromagnetic, magnetic, electrical resistivity or gravimetric methods.
There are other methods that can be used to determine where the water is on your plot and these are employed by water dowsers. Dowsing tools vary from the old-fashioned Y-shaped stick, which was probably taken from a willow tree, to dowsing rods which are often L-shaped metal rods held in each hand, but some are made of wire, glass or plastic. The modern trend is toward using a pendulum made of crystal, metal or other material, suspended on a string or chain. There are other methods that are even more intuitive, but the fact is that nobody can claim to have 100% accuracy in indentifying the site and depth of groundwater on your plot.
Having established the location and quantity of water you have, you may decide to sink a borehole. The Borehole Water Association of Southern Africa will send you their membership list, which will include drilling contractors in your area. You can e-mail them on info@bwa.co.za or phone on (011) 447-0853. As the association points out on its website: “A borehole is an asset that should last you at least 10 to 15 years at very little ongoing cost, provided you buy correctly at the start! If you don’t, it can become a very expensive and time-consuming liability with continual repair or replacement of pumps, the causes of which could either be traced back to poor borehole construction or incorrect pumping or pump installation.”
As the client, you are responsible for the cost of the drilling, regardless of how successful it is. Be prepared for noise and a certain amount of mess during the drilling process. Warn your neighbours if they are likely to be affected. The drilling contractor is dealing with a number of unknowns in terms of the final depth and the time taken to complete the drilling, so the quote that you are given will probably exclude possible “add-ons”.
The driller should cap the hole to prevent foreign material from entering the hole.
Once the drilling is done, the next step will be to have the pump installed. This often takes a number of days to take place. When it comes to having the pump installed, ask that you be provided with proper yield, drawdown and step tests. The correct pump size and installation depth are dependent on this information. The test is done by installing a test pump into the borehole and then pumping water from the borehole at specific rates over a certain time. During the test the change of the water level in the borehole is monitored and recorded. The test can take up to 72 hours.
Ascertain beforehand that the pump installer uses a qualified electrician to sign the installation off.
The borehole number should be stamped into a metal plate on the pump stand or borehole plinth, along with other information such as depth and completion date. Borehole data, including GPS co-ordinates, depth and yield, must be submitted to the Department of Water and Sanitation in order for the borehole to be recorded on the National Groundwater Archive, even if water use registration/licensing is not required.

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