There are various ways in which water wells are constructed. The method used to construct the well will depend on the geological conditions and the purpose for which the well is being constructed. For instance wells constructed in hard fractured rocks use extended casing down the borehole. The end of the casing usually remains open. On the other hand when constructing in unconsolidated sediments such as sand and gravel, a well screen is placed in the aquifer. The following is a simplified description of the process of constructing a well.
The well construction crew has to drill a hole through the ground. They can use a variety of drilling methods including starting by hand digging and then advancing on to technical and more sophisticated drilling rigs. The point of the drills is to create a borehole. Once the well location has been chosen, the drill rig is set up over the area and drilling begins to desired depth.
Casing and screening
After tapping the water table or desired depth for the borehole, the construction team works on installing a casing and screen. The casing prevents the borehole from collapsing since the diameter of the borehole is usually quite small compared to the pressure from the surrounding soil and rocks. The screen is a small filter that allows water to pass through while preventing unwanted materials such as sand or soil from contaminating the well water. The screen is attached to the first process of casting and other pieces of casting are added progressively until the entire borehole is cased.
Installation of the artificial filter pack
Depending on the intended use of the well, an artificial filter pack may be placed around the screen of the well. This filter will further prevent fine particles from contaminating the water and making it cloudy.
Grouting is also necessary to further strengthen the walls of the well and prevent it from collapsing. Grouting involves filling the space between the casing and the borehole with cement or clay. Grouting prevents contaminants from leaking into the well from the surface and intermixing of ground water between water-bearing zones.
Well development is the last step in the process. At this point the construction team attempt to maximize the well yield. Well development repairs any damage that may have occurred to the formation of the well during drilling, it also removes unwanted fluids to restore the natural properties of the aquifer. The techniques used for well development vary from simple to complicated depending on the desired effects of the process. The construction team can bail the well or carry out high capacity pumping and jetting in the well. Most of the well development practices occur at the screened area of the well since this is where water is expected to enter the well.
Pump installationAfter well development, a permanent pump may be installed and the well sealed. The permanent pump will be constantly drawing water from the well to the surface and pumping it to nearby building or farms for irrigation.
Posted By: KCW Waterwell Service http://kcwwaterwell.com/