In India, the geological department or the Central Ground Water Board should be contacted as and when the proposal for deep tube wells is made. Generally, if the normal water table is at a greater depth it would be economical as well as preferable to install a deep tube well instead of an open well.
There are various steps in the construction of bore wells such as:
- Selecting the right drill contractor: This is the first and most important step in constructing the bore well. The contractor must have appropriate work experience and knowledge of the local geological factors. The existing wells in the area should be properly surveyed as it will help in providing important information about the typical yields, water quality, prior drilling success rates, aquifer information etc.
- Selecting the right bore well site: The performance and safety of the well is directly dependent on the exact site location. Generally, contaminants enter and pollute the water from the top or around the walls of the bore well casing. It should be ensured that the bore well can be cleaned, tested and maintained easily in the long run. The ground that is in the immediate surroundings of the well should be sloped away from the bore well to ensure that the run off from the surface does not contaminate the well.
Sewage and other wastes may enter the well through the upper layers of the ground and into the aquifers. - Trial boring: This refers to a step where samples of strata are examined for yield and samples of water are taken for analysis before sinking any pipes. This will determine the areas in the bore well that require strainers for the necessary quantity of water that is required. The strata in which the location of strainers should be installed is hence located.
- Water sampling for analysis: In cases of large water supply, it is important that the water be drawn from as deep as possible to eliminate the danger of bacterial contamination that is often seen in water drawn from the upper strata. Generally, the water drawn from a larger depth is much more pure from bacterial infestations. However, he water drawn from such depths may contain certain dissolved impurities and chemical analysis of this is done to determine if the water is suitable for drinking and human consumption without having negative effects on health. Thus the testing stage is of vital importance.
- Distance requirements: There are various regulations that define the provincial regulations of minimum distance requirements from the bore well. A water tight septic tank should be at least 10 meters away from the bore well while the well cannot be constructed below 450 meters distance from a landfill or waste disposal unit. The bore well design and construction details are finalized on after a test hole is created and all the geological zones have been marked and logged. There are various designs relating to the well design multiple decisions must be made based on the type of well, intake design, capacity etc.