Drilling a borehole?We'd like to make the process as easy as possible for you.
There are so many aspects that you need to consider when drilling a borehole that it’s easy to feel a bit overwhelmed.
As an end user, you need some knowledge to communicate effectively with your service providers so that misunderstandings can be prevented. Ultimately, we’d like you to get the best possible yield from your borehole with the least amount of disruption.
So we’d like you to make the right decisions at the start of the process and invest wisely for long-term returns. To do this, we can supply you with the: Borehole Checklist
The Borehole Checklist
A borehole is an asset that should last 50-80 years, with very low maintenance costs in the first 10-15 years. But for this to happen, you need to make the right decisions at the start of the process and invest wisely for long-term returns. The following checklist will help you to do just that.
LOCATION OF WATER
Do some of your own initial research to get a general idea of the success of the boreholes in your area. Although this doesn’t replace a professional opinion, it will help to set your expectations. Take this opportunity to get to know your neighbours a little better and then ask them the following questions:
- Do you have a borehole?
- How much water does your borehole yield?
- How deep is your borehole?
Contact a geohydrologist to site the best location to drill the borehole. In an urban environment, factors such as power lines, pipelines and underground cables need to be considered as they have an effect on the instrument readings AND the position of the hole. Bear in mind that the mobile drill rig can weigh 15 tonnes or more and have three axles. Where will it fit in your property?
Most geohydrologists have a good working knowledge of conditions existing in their areas of operation and even although conditions might not be conducive for the use of geophysical instrumentation in your area, they will nevertheless be able to give you some valuable input into the siting process.
Here are some of the questions you’ll need answers to, and things to check when you are choosing a driller for your borehole.
- Get references from previous clients who have used the driller recently, and if possible, get a reference from a client who used the driller more than a year ago – this will help to give you an indication of the long-term quality of the driller’s work.
Does the driller work to a recognised standard?
The SABS standards for the groundwater industry are listed in SANS 10299-: 2003 – Development, Maintenance and Management of Groundwater Resources.
Is the driller’s equipment clean and in good condition? Look for:
- – No oil or fuel leaks
- – No frayed hoses and/or cables
- – All the operators are equipped with personal protection equipment
- – Spectators are kept at a safe distance from the machines.
What type of casing/well screens will be used?
The type of formation that contains the water will have a significant influence on this. Soft, sandy formations need to be screened to allow the water in but stop the sand from getting into the borehole. Allowing sand to enter the pump will cause premature failure of not only the pump, but also the entire installation.
What will the diameter of the borehole be?
A diameter of 152 mm (6 inches) complete is viewed as the standard for a domestic borehole. Larger diameter holes are considerably more costly and are the preserve of large irrigation, water supply and mine dewatering systems.
If you have obtained professional help in establishing the approximate depth at which a water bearing formation can be expected, you will need to communicate this to prospective drilling companies. Deep boreholes (+150m) can require larger machines that are not available to some contractors, or will not fit into your property.
Will the driller do borehole development? / How will the driller improve water yield if necessary?
Once the hole has been drilled to the final depth, it will need to be thoroughly flushed to remove all loose debris. In addition, the water bearing formation will need to be worked in a way that allows easy passage for the water to enter the borehole. This process is called borehole development. If the driller does not understand the meaning of borehole development, get another driller.
You only have to pay if the driller drills to the depth specified in the contract (unless the driller finds water at a lesser depth and it is agreed, in writing, to stop drilling).
Will the driller be able to continue drilling through intersecting clay, unconsolidated sand or hard rock?
Drilling through soft and hard formations requires certain skills and equipment. In addition, there could be additional costs incurred by the driller. The BWA Standard Form of Contract takes these into account by stating, upfront, what additional charges are applicable if these difficult formations are encountered.
The BWA recommends that the driller provide samples of material from each metre drilled. These samples are very useful to geohydrologists and to contractors who have years of experience. You can take a number of photos (a mobile phone camera is sufficient) of the sample mounds and save them as part of the records pertaining to the installation.
Is the provision of a driller’s log of the borehole included in the price? A driller’s log gives details of the construction of the borehole such as total depth, diameter(s) casing types, size(s) and length(s) and types of screens installed at specified depths. Should the driller provide a turnkey service whereby, in addition to the drilling, the pump is selected, installed, and commissioned then an electrical clearance certificate, a yield test certificate, and a form containing pump details, and commissioning data must be provided.
These documents are a definite advantage when the time comes to sell your property.
Does the driller have a standard contract?
This is of vital importance to both parties. The BWA Standard Form of Contract is available on request. It’s always best to get it in writing!
Is the driller a member of the Borehole Water Association?
Membership of the Association shows that the driller you are dealing with is committed to the long-term viability and professionalism of the industry and that the drilling company is part of a network of professionals that will ensure accountability. The installation of a borehole requires a significant investment and therefore requires the involvement of companies and individuals who are skilled in providing all the necessary products and services.
THE PUMP INSTALLER
Can the pump installer provide you with proper yield, drawdown and step tests? This is required to select the correct pump for your needs. If the installer does not know what this means, do not use this installer. If your property has a borehole as its primary source of water, financial institutions will require a yield test certificate from a reputable contractor before a bond is approved.
Does a qualified electrician sign the installation off? If ANY electrical work is done on the installation, it is best to get a qualified electrician to complete the installation. Companies or individuals who carry out electrical work, for which they have no certification, will be held liable for any damages or injuries that result.
Does the installer select the correct pump for your application? Remember, a more powerful pump does not equate to a better pump. A pump that is over-specified often results in premature system failure. If the pump is too small, it won’t meet your needs. Sizing a pump is a match between what is NEEDED and what the borehole can DELIVER.
OTHER FACTORS TO CONSIDER
Unfortunately, the drilling contractor cannot guarantee that the borehole will intersect water and therefore the client does take a certain amount of risk, as the client will be responsible for the cost of the borehole, regardless of what the ultimate yield is.
A modern drilling rig is large and heavy, which means that the drilling process may lead to some unavoidable damage, especially in residential gardens, even if the contractor has taken reasonable care. In this case, the contractor cannot be held responsible.
Drilling rigs are noisy and the drilling process is messy. You are encouraged to warn your neighbours that drilling will be happening on your property.
Under the new water law, your water usage may need to be authorised. Some pointers are:
The Department of Water Affairs generally gets involved when the water is used for commercial purposes. Schedule 1 of Act 36 of 1998 gives more detail on water usage applications that do not require registration. Water for use in a household and for gardening (non-commercial) is listed in schedule 1. Alternatively, your local municipality/council may require that permission be obtained to drill a borehole. Members of the BWA can assist with establishing whether or not your local authority requires registration.
Ensure that there are no electrical cables, sewage or water pipes under the ground where the drilling will take place. Consulting your house plans would be one of the ways of checking this.
Unfortunately, there are several unknowns, which could all result in additional services being required to successfully drill the borehole.
All of these add-ons will impact the final cost of drilling a borehole. Discuss these potential add-ons with the contractor and agree on a maximum amount to be charged for these add-ons, if they are required. The BWA’s Standard Form of Contract has a specific section for many of the common (potential) add-ons.
Drillers levy a surcharge for drilling through very hard rocks, e.g. drilling into dolomite formation requires specialised expertise.
Once the borehole has been drilled, you will need to allow at least two weeks for the pump installation to be completed – this takes into consideration the ordering of pumps and other equipment and the installation time.
Make sure that the driller caps the hole after drilling to prevent any foreign material from entering the borehole.
The estimation of the cost of installing a fully functional borehole varies considerably. In some areas, viable quantities of water can be obtained at 30m. In other areas, a hole might have to be drilled to 150m+. The cost of the drilling, casing, riser piping, pump and electrical control systems will be completely different. Call on neighbours and find out about the depth and yield of their boreholes. Next, contact the BWA for the contact details of a number of contractors that operate in your area. BWA members will be pleased to give you an idea of how deep you can expect to drill and a rough estimate of the total cost. If you feel that this amount is affordable, then the process of location, drilling and equipping of the borehole can begin.