DRILLING OF WATER WELLS/TUBEWELLS
This method is suitable for soft and fissured rock formations. In purely soil formations, it gives very high working rate. This method consists in breaking down and pulverizing the subsoil material by repeated blows with a cutter made of hard metal. The pulverized material mixes with water and then is removed. Sometimes this method is also called cable tool method. Bores as big as 30 cm in diameter and over 200 to 300 m deep can be drilled conveniently which meet normal requirements.
Before boring the hole, water must be poured in. As the plunger drops down, slurry fills it up. The plunger is then taken out and the slurry is removed by turning it upside down. The plunger is again lowered and dropped into place again. This process continues until the casing pipe reaches a predetermined depth. When this happens, additional pipe may be added at the top of the first one. To increase working rates, machine percussion can be used on casing pipe as well as inside strainer pipes.”
A tube well is a type of water well in which a long, 100–200 millimetres (3.9–7.9 in)-wide, stainless steel pipe or tube is bored underground. The lower end is fitted with a strainer, and a pump lifts water for irrigation. Tube wells contain sanitary seals that prevent seepage from the ground above the aquifer from leaking into it, and prevent leaks from ground seepage into an aquifer below. Tube wells are often used in sandy areas because they are less prone to clogging than other types of wells; however, if there is any chance that water may be contaminated by sand or silt particles, then it is best to use another type of well instead.
