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Module 7 — Troubleshooting Water Well Problems
Over-pumping
A well is over-pumped if water is withdrawn at a faster rate than the well was designed for or
the aquifer is able to produce. Over-pumping is the most common well problem that leads to
premature well failure. Over-pumping not only depletes the groundwater aquifer (or source),
but it rapidly increases the rate of corrosion, incrustation and biofouling related problems.
Over-pumping also increases the rate of sediment particles moving toward the well, causing
plugging of the perforated area where water flows into the well. It can also cause the aquifer
to settle and compact which further restricts water flow to the well.
Dissolved Gas in Water
The presence of gas in water wells is common in Alberta. Oxygen, carbon dioxide, nitrogen,
methane and hydrogen sulphide may occur naturally in some of the aquifers in which water
wells are drilled (e.g. coal seams, fractured shales and sandstones). When gas is present,
it is held in groundwater under pressure. Pumping water wells completed in such aquifers
can reduce the pressure, releasing the gas. Sometimes gas in groundwater can affect the
operation of your well. Even if gas is present, it may still be possible to use your well in
a safe manner. Refer to the troubleshooting guide on page 63 for methods of controlling
dissolved gas in water.
Aquifer Problems
While most well problems are related to the construction, development or operation of the
well, the formation can also be a source of problems.
Reduced aquifer yield can be caused by lack of recharge. For example, the amount of
water withdrawn can exceed the recharge from rain and snow melt. This is referred to as
"
mining the aquifer". Sometimes the decline in water level is seasonal. Typically water levels
are higher in spring and lower in the fall. Extended dry periods can also impact water levels,
especially in shallow water table type aquifers.
Checking the water level in your well is an important maintenance procedure. You will be
able to identify water level trends and identify well problems or aquifer depletion before the
problem becomes serious.
Now go back to the exercise at the start of this module. Try to identify possible causes for
each problem you identified.
For more information on checking water
levels, see Module 5 "Monitoring and
Maintenance of Your Water Well".
If you are pumping water at a rate close to
the well's capacity, excessive pump cycling
can increase the problem of biofouling.