Helderberg Water Drilling Company
How to construct a borehole
A borehole is an expensive investment. Good construction is therefore crucial. Here are some helpful tips from earth science and groundwater consultants.
The first step in successful borehole construction is knowing what you want. How much water do you need and what will you use it for? Irrigation? Domestic supply? Stock watering? This will affect the water quality required. If you need water for toilet flushing and sanitation, for example, a low-yielding borehole with saline water will be sufficient. But it will be of no use if you require high quality water for crop irrigation.
Do your homework
Check with neighbours to see who has a borehole. If they do, what is the quality like and what is the yield? This will give you an idea of your chances of finding water. Also consult a geologist or hydrogeologist (groundwater specialist) with experience in the region where you require water. He will be able to tell you immediately, before any detailed assessment is done, if you’re likely to get a high-yielding borehole of 5l/s or more, or a low-yielding borehole (less than 1l/s).
After this, he can assess the surrounding geology and subsurface conditions to see if the site is underlain by poor-yielding aquitards and aquicludes (rocks that retard water flow, usually forming barriers or seals above aquifers).
Understand the risk
While the driller should exercise care and diligence, he is not responsible for the water quantity or quality.
This is a phased assessment, starting with a desktop study and followed by a field visit and borehole siting. The assessment should be divided into phases, each with its own costs, so that you don’t have to pay a large amount of money up front. The desktop assessment, for example, may indicate little chance of good quality, high-yielding groundwater (despite your neighbour’s experience). If it’s positive, you can proceed with the actual siting and drilling.
Be aware of costs
There could be additional costs for drilling through certain geological formations. The contractor might have to set up a base camp where staff are fed and housed. If a local community is involved, you will have to factor in visits and meetings. The driller should be able to provide a bill of quantities – that is, the cost per unit of drilling a certain diameter at a certain depth. Instead of a bill of quantities, though, many farmers might favour a lump sum instead, with a single price per borehole. A lump sum contract may prevent over-drilling, but it can also encourage under-drilling, with boreholes not being drilled to the required depth.
This should include witnessing and certifying critical milestones, as well as ensuring that boreholes are drilled and completed to specification. Supervision of drilling by a geologist/hydrogeologist can ensure that the correct data (depth, yield and quality of water strikes) is collected during drilling. This will assist in any future pumping tests or licensing requirements.
These review the progress and quality of the work. At the meeting, the contractor should submit a progress report and detail any new challenges. Not all issues can be resolved on site and a consultant may have to be called in.
This should be based on actual work completed. When and how much must be stipulated in the pre-agreed contract.
Check that the driller has met all the contract requirements, the installation is functioning properly (if pumping equipment is installed) and all the required data has been collected and submitted.
These tests, along with subsequent analysis by hydrogeologists, can determine the safe, sustainable rate at which a borehole
should be pumped, as well as what depth to install the pumping equipment. They will also help to ensure that the borehole does not dry up over time.