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.
Drilling
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
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
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 installation
After 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/
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