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Drilling a Water Well
In areas without piped water, homeowners
rely on wells to
provide them
with fresh water. If water is
50 feet or
less below the surface and you
are going
through soil rather than rock,
less expensive
methods than drilling can be
used. You can
have a contractor drive a small
diameter
pipe to the required depth, or
you can dig
a well by shovel (like the old
fashioned
ones you sometimes see lined
with brick or
stone). One problem with these
shallow wells
is that the water is prone to
contamination,
making it unsuitable for human
consumption.
Another is that the water table
drops deeper
into the ground during dry periods
and times
of high use, causing shallow
wells to sometimes
run dry. If the well has to be
of any real
depth to reach the water source,
it is a
job best left to a professional
with the
right equipment.
Drilling a well involves a lot of uncertainty,
although an experienced driller in your area
can be better at estimated the work than
others. Before signing, be sure you understand
what the driller will do for what price,
who assumes the cost of a dry or poorly performing
well, and the maximum depth and ground conditions
the driller will work with. The National
Ground Water Association (NGWA) is a professional
association that certifies contractors in
this field. Professional designations include
Certified Well Driller (CWD) and Certified
Pump Installer (CPI or CWD/PI), both of which
require examinations, continuing education,
and clean legal records. The Master Ground
Water Contractor (MGWC) is the highest professional
designation in this field, and requires at
least 5 years of experience in the industry
plus demonstration of superior knowledge.
The precise methods used to drill a well
will be dictated by several factors, including
the depth of the aquifer (underground water
source) and the type of ground (rocky or
soft soil) that must be penetrated to reach
it. Needless to say, the deeper the aquifer
and the rockier the ground, the more expensive
the process will be.
When contracting for a well,
remember that
there is more to it than just
drilling the
hole:
- The well must be lined with a “casing” to
prevent soil from collapsing
into the borehole
and to create an unobstructed
conduit for
the water to be brought to
the surface. This
casing normally is either a
steel or plastic
(PVC) pipe, but sometimes concrete,
cement,
or fiberglass. The pipe must
be strong enough
to withstand being driven down
the borehole,
with the stresses on the pipe
increasing
as the depth of the well increases.
The casing
must also prevent the invasion
of potentially
contaminated groundwater into
your well.
Steel casing is the norm for
wells through
hard rock. Steel is stronger
and resists
heat better, but it can corrode
and attract
mineral deposits. PVC is lightweight,
easier
to install, corrosion-resistant,
and cheaper.
- The well must be capped. Well caps include
an air vent that balances the
air pressure
between the inside of the casing
and the
outside atmosphere. They also
allow the venting
of unpleasant or explosive
gases. If explosive
gases are at all likely to
be present, the
vent must be outdoors, not
indoors. The vent
also should be properly screened
to prevent
foreign objects, insects, etc.,
from entering
the well. The casing and cap
must extend
at least 6-8 inches above the
ground (and
possibly much higher if the
area is prone
to flooding) to prevent contamination
of
the well.
- The disinfection of the well.
When the well is complete, you
can verify
the depth by tying a weight on
a string or
tape and lowering it in. The
well's yield
is normally expressed in gallons
per minute
(gpm). Ask the
contractor how many gpm were withdrawn during
testing, how far the water level dropped,
and how long it took to recover. These facts
will give you an idea of how intensively
you can use your well.
Be sure that you get a copy of the well record
from the driller and keep this with your
deed. When buying a house with a well, be
sure that you see their well record.. |
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