Module 8 — Protecting Your Well From Contamination
67
Well Pits
Well pits provide a place for contaminated surface water or shallow groundwater
to collect. When this water sits in the pit, it can contaminate the aquifer by seeping
around the outside of the well casing or flowing into the well. This type of construction
also makes it very susceptible to contamination by small animals and insects (see
Figure 3, Well Pit). For this reason well pits are no longer allowed.
Well pits can also be a deadly safety hazard. With changes in atmospheric pressure,
air from within the well casing can displace "normal" air in the well pit. Well gases
or low oxygen content resulted in human deaths, even recently. People entering the
well pit can be asphyxiated. Wells located in basements and pump houses can also be
susceptible to this problem.
Methane gas build-up can cause explosions.
Prevention:
Pitless adaptors provide a safe, sanitary and frost-free connection from
the pumping system to the water well (see Figure 4, Pitless Adaptor).
For more information, see the publication Pitless Adaptors, listed in
Module 12 "Other Resources".
Figure 4 Pitless Adaptor
Provincial regulation now prohibits the
construction of well pits.
Prevention:
If a well pit exists, do not enter
it alone and without ventilating
it aggressively beforehand. It is
best to have well pits removed by
an experienced contractor with
certification in working in
confined spaces.
Figure 3 Well Pit