Borehole cleaning and rehabilitation is a common procedure
aimed at addressing specific issues affecting a borehole and its performance.Boreholes are subjected to a number of occurrences that may lead to damages or deterioration of the water quality. This explains why borehole cleaning and rehabilitation is vital. This often involves use of specialized equipment and chemicals to eliminate biological growth, mineral deposits, and other contaminants. This process is applicable for both small residential boreholes to large-scale industrial and commercial projects.

Borehole cleaning and rehabilitation involves the following steps:

Assessment of the damage

Assessing the damage involves a site visitation and going through all the important records that give vital information regarding the borehole. This information includes the drilling diameter, initial depth, original yield against current yield, and the materials that were used in lining the borehole. Moreover, a thorough inspection of the area is carried out to check the possibility of pollution or the contamination of the groundwater. There may be leaks from septic tanks or fractured sewers. There is also assessment of the topmost part of the borehole for any damage. This includes the borehole casing, bore apron, sanitary seal, and the pump’s connection.

Furthermore, a rough estimate of the amount of silt and debris in the borehole is provided. The pipes are inspected for any blockage or clogging. Afterwards, an estimate of the resources need for rehabilitation is provided, including materials, equipment, time, and skilled personnel.

Borehole and hand pump repair.

Usually, a high-pressure compressor is employed to flush any sediments from the borehole. Any damages on the riser pipe and pump are repaired and the worn out parts replaced. The pump is then reassembled together with the riser pipe and reinstalled with all other borehole components. A test run is made on the pump to check whether it is working optimally and checked for clear water, and maximum flow rate. The drainage apron and the clay sanitary seal are also repaired to prevent future contamination of the groundwater from the surface.

Disinfection and re-commissioning of the borehole and hand pump

Before recommissioning is done, the borehole is first disinfected via chemical cleaning. This process is often takes up to 3 days after which the borehole is dewatered to remove all the chemicals and residue. The most common disinfecting method is chlorination for a clean water supply.

When is the right time to clean/rehabilitate a borehole?

There are a number of instances where it is recommended to have a borehole cleaned and/or rehabilitated.
One such instance is if the borehole has been around for over 3 years. Also, if you happen to relocate to a new place with an existing borehole, it is advisable to have it cleaned especially if you have no prior information on the water safety. Moreover, if you note a depreciation in the borehole yield—if the water supply drastically drops from a high supply to low supply—you should consider rehabilitation. Other occasions include a notable increase in the water iron content, after natural disasters such as flooding or earthquakes, or when the submersible pump put in place fails with no apparent reason.
The right borehole cleaning/rehabilitation method should be selected depending on the nature and extent of the damage, borehole condition, user’s opinion, and other logistic and technical options. The rehabilitation work may vary from simple surface repair to unclogging and even renewing of borehole components.

Why is it important to rehabilitate a borehole system?

Borehole rehabilitation is often needed when the borehole in question is no longer producing enough water or water of good quality. The process tends to involve cleaning, removing obstructions, and repairing damaged parts of the casing or lining. More often, borehole rehabilitation starts with a thorough inspection to assess the condition and extent of damages, after which a team of experts perform the rehabilitation.

FAQs

What are the common causes of borehole damages?

Any arising issues with boreholes can be attributed to its age, construction quality, operational use, and where it is located. The possible causes for damage include mechanical clogging, erosion, biological clogging, bacterial and electrochemical corrosion, and chemical encrustation. All these causes lead to a reduction in the performance of the borehole.

How can I tell my borehole needs cleaning?

You may experience a number of signs that will lead you to the conclusion that your borehole needs to be cleaned. These include unpleasant odors and taste, a decline in well production or reduced efficiency, rusty slime buildup, and excessive corrosion on the plumbing components.

Conclusion

The integrity of any borehole has a direct relation to the water quality, amount of water supply, and overall performance. Therefore, it is very important that any borehole is in tip-top shape. The best and more effective way to make this possible is by performing borehole cleaning and rehabilitation.