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Well Construction and Setback Distances
Domestic water wells that are not constructed
properly pose a threat to the quality of your drinking water
and may even threaten your neighbor's water supply. Well construction
must meet applicable specifications. Wyoming does not have a
licensing board to certify well drillers; therefore, it is the
property owner's responsibility to have their well driller comply
with proper design specifications when drilling a new well. While
it may be less expensive to construct a well that is not within
specifications, the potential cost to correct a groundwater contamination
problem caused by improper well construction far outweighs the
cost of having a new well designed and constructed properly. Contact
the Wyoming State Engineer's Office for well design requirements
at (307) 777-7354.
Construction standards include making sure
the wells are sealed at the ground surface to reduce the risk
of surface water carrying bacteria, pesticides, fertilizer, oil
products, or other contaminants to your drinking water supply.
In addition to sealing the well at the ground surface, subsurface
seals are needed to seal the annular space between different
geologic and/or aquifer units. The annular space is the area
between the sides of the drilled boring and the well casing that
is placed in the hole. Annular seals should be placed where confining
layers are present to prevent mixing of water from different
aquifers. The main purpose of the annular seal is to prevent
the threat of surface water and/or shallow groundwater flowing
down alongside of the casing and contaminating the water supply.
Why is the location of a private domestic
well important? Frequently well locations are chosen based on
convenience, not consideration of protecting domestic wells from
potential contamination sources that may be in the area. Wells
should be located at least some minimal distance away from any
contaminant sources. The distance your well is away from a potential
source of contamination is called the setback distance. Current
activities or sources of contamination may need to be relocated
to decrease the likelihood of contamination. An example of a
setback distance is the spacing between your water supply well
and septic tank should be at least 50 feet, and the leach field
at least 100 ft. away. For more information about siting regulations
contact the Wyoming Department of Environmental Quality, Water
Quality Division at (307) 777-7781.
Barnyards and Other Livestock Holding
Areas
Livestock holding areas have the potential
to be a source of nitrate and bacteria contamination if groundwater
is shallow, or a groundwater pathway exists, such as a fracture,
fault, or an improperly constructed or abandoned well. Ideally
these types of activities should have no manure discharge into
groundwater or surface water. Factors to be considered when citing
a new barnyard or holding area include location and distance
to existing water supply wells, topography, soil type, and depth
to groundwater.
REMEMBER: Animal barns or yards should be
located at least 50 feet away from wells.
Fertilizer and Pesticide Storage Areas
and Application
Pesticides, such as herbicides and insecticides,
and fertilizers have potential to contaminate groundwater. After
being applied to the soil they may migrate through the soil to
the water table. However, the highest potential for contamination
occurs in areas where pesticides and fertilizers are mixed, and
where application equipment is loaded and rinsed after each use.
Pesticides and fertilizers can find their
way into groundwater through a poorly sealed well or by improperly
disposing of partially filled containers of pesticides or fertilizers.
REMEMBER: Pesticides and fertilizers should
be stored at least 100 feet from wells. Pesticide and fertilizer
mixing and loading should be done at least 200 feet from wells.
Well Maintenance
Existing wells must be maintained and operated
correctly to prevent well deterioration and aid in preventing
contamination of your water supply. Similar to your car, your
well needs regular maintenance. This maintenance includes simple
measures; such as, keeping the wellhead area clean and accessible,
and moving any pollutants as far away from the well as possible.
Other more extensive measures may involve hiring a qualified
pump installer or well technician to inspect the operation of
the pump and the integrity of the well casing. Many problems
can be prevented by following proper well design and installation
practices during the construction of the well. Your well should
also be sampled regularly to verify that no contaminants are
present in the water.
Well Sampling
Well water should be sampled at least every
year. Sample your well any time you think a health problem in
your water system may exist, or if you notice significant changes
in the taste, smell, or color of the water. At a minimum, the
laboratory should analyze for the following parameters: pH, nitrates,
ammonia, total coliform bacteria, and total dissolved solids.
If you suspect any other contaminants, such as hydrocarbons from
petroleum leaks or spills, or spills of pesticide liquids, include
these specific parameters in the test. If any parameters in your
well exceed acceptable limits, always retest immediately to verify
the first test.
The Wyoming Department of Agriculture
Analytical Services Laboratory, 1174 Snowy Range Road, Laramie,
WY 82070, (307) 742-2984 will analyze your samples.
If your water system contains over one coliform
bacteria per 100 milliliters, it may not be safe to drink due
to bacteriologic contamination. Contact a qualified well contractor
to disinfect your well, tanks, and distribution system. If the
sample was taken at your water tap, the bacteria may be present
within your pressure tank or distribution system. Exposure of
the well or piping system is sometimes necessary in order to
perform various procedures such as repairs or maintenance. Please
remember that whenever the well or piping system is exposed,
it may be invaded by foreign matter that contains bacteria. The
well system should be disinfected prior to placing it back into
service.
Plugging Abandoned Wells
Improperly
abandoned wells are one of the most serious threats to our
groundwater. These are wells that are no longer used but
have not been sealed or capped, leaving an open pipe directly
to the aquifer. Contaminants can be washed down the hole
from the surface or dumped intentionally into the well, polluting
the groundwater. Contaminants can also flow from a polluted
aquifer into a clean one through a poorly sealed well. Abandoned
wells also pose a physical threat to small children and animals.
We've all seen news stories of children becoming trapped
in wells as small as 10" or less in diameter.
Signs
of abandoned wells include:
- Pipes sticking out of the ground
(see picture below)
- Old windmills (they are often
near wells)
- Depressions in the ground
- Concrete pits
- Small buildings that could have
once been a well house
- Additions to old homes (wells
were sometimes put under porches to prevent freezing)
Abandoning
a well usually involves hiring a professional contractor.
The contractor will remove any pumps and pipes in the well,
and may also try to remove the casing. They will then seal
the well from the bottom up with bentonite or bentonite-cement.
Cost depends on well depth and condition, but usually runs
a few hundred dollars. An alternative is to cap the well
with a welded steel plate. This option is much less costly
and allows the well to be used later, but does not prevent
groundwater contamination as well as sealing does.
Please
contact the Wyoming State Engineer's Office at 307-777-6163
if you have any questions or concerns about water rights or
reporting requirements related to abandoned wells or sealing
a well.
Your
local well driller would be able to answer any questions about
the cost or techniques of sealing a well.
Contact the Wyoming Department of Environmental
Quality, Water Quality Division, 122 W. 25th St., 4W, Cheyenne,
WY 82002, (307) 777-7781 for more information about properly
plugging old and abandoned wells.
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