The first operation after drilling the hole (fig. 9-14)
is to set the screens and casing (fig. 9-15). The casing
prevents collapse of the drilled hole walls in
unconsolidated formations. The screens prevent
collapse of the drilled hole wall in the aquifer while
allowing water to enter the casing freely. After the casing
is set, the well is gravel-packed (fig. 9-16). Gravel
packing is placing graded aggregate on the outside of
the casing to allow for more production and prevent
“fines” from entering the well pump, tanks, and
systems.
When the screens, casing, and gravel pack have
been completed, the well is ready for development.
Development is accomplished by removing the drilling
fluid from the aquifer and the employment of any means
that induces an alternating flow of water in and out
through the screens. This action stirs up the
unconsolidated material in the aquifer and allows
removal of the finer particles. Gradually, the coarsest
particles become stabilized around the screens, and the
last vestiges of drilling fluid are removed, permitting the
well to yield its maximum capacity.
A variety of methods are used for setting screens,
removing drilling fluid, and developing aquifers. The
method used for either of these operations is often
determined by the tools and equipment available.
When development of a well is complete, it is
required to grout as a sanitary protective measure to
prevent seepage of surface water or contaminated water
from water-bearing formations above into the aquifer.
Grouting is accomplished by cementing from the top of
the gravel pack to the annular space between the well
wall and casing (fig. 9-17).
WELL DRILLING SAFETY
Safety is paramount in all construction operations.
You must always be safety conscious and on the alert
for potential dangers to personnel and equipment. Safety
considerations cannot be overemphasized.
1. Hard hats area must and should always be worn.
2. Gloves should be worn to protect hands when
handling wire rope.
Figure 9-14.-Drilling the hole.
Figure 9-15.-Casing the hole.
9-16
