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Water catchment is a fundamental element for water supply to the factory. Failures generate immediate consequences. Protection maintenance and follow-up are key points for a good plant management.

The catchment area is the land area where the water drawn from an underground source falls as rain. This land may or may not be under the control of the bottler. The following protection measures are recommended:-

Protection of the well and the catchments field
Once the drill completed it is necessary to protect it against any source of external pollution. Ideally catchments are framed with different protection zones

The vulnerability of ground water to various pollutions is conditioned by several factors of the filtering power of ground.
  • Thickness of the unsaturated zone of the ground reservoir.

  • Maximum drainage speed of underground water: connection with phenomenon of dilution, degradation and fixation of polluting agents.

  • Natural protection of aquifer: thickness of existing waterproof natural cuttings insures an efficient protection against surface pollutions.

  • Type of phreatic: Superficial and free ground waters are more vulnerable than deep and confined ground waters.

A well does not catch only the water in the immediate surrounding around the strainer. The hydrodynamic rules assume that a more or less important perimeter exists in witch the ground water is influenced by pumping. A specific radius can be determined around each drill construction.

When pumping starts, the water around the strainer comes first and the level drops down immediately. This drop imbalances pressures on both sides of the well and ground water flows from the external to the internal side of the well. The surface of the ground water hollows with a shape of cone.

During a constant pumping session the depressed cone becomes deeper and larger. The influence radius is the distance beyond witch the drop is not measurable.

The progression towards stabilization depends from the geological properties of the ground.

Flow in pumping conditions
In natural conditions the ground water is in a stable dynamic balance. Pumping modifies this balance and creates a drop of the surface of the ground water. This induces the water flow from outside to inside the strainer.
Two zones must be distinguished:
  • The influence zone in witch levels are modified and discharged by pumping.

  • The appeal zone is the section of the influence zone in witch the flow lines move to the strainer. This zone includes the rhumb-line of feeding continued to the limits of the system.

Any occurring threat or pollution from neighbouring activities inside this zone will end up in the catchment such as:
  • Use of pesticides and fertilisers if farmed.
  • Excess stocking with animals.
  • Dumping of industrial, domestic, or farming waste etc.
  • Polluting activity - no industrial/domestic or farming activity.
  • Major earthworks/building projects.
The downstream limit of this zone is considered as the limit of the protection zone close by perimeter. The dimension of this zone varies according to the pumping outflow

Protection perimeters
Setting up safe protection perimeters has economic and sanitary consequences. This is a long and complex mission. It has to be carried out by an agreed Hydro geologist.

The proposed perimeters must guarantee a maximum security for the protection of ground water. However an excessive extension of the perimeter may be incompatible and do not match with excessive economic costs.

Three zones can be retained:
  • Immediate protection zone around the catchment including
    Constructing a surface water drainage ditch uphill from the source works to divert rain water run-off. This is especially important in hilly areas.
    Fitting of a lockable closure on the source works to prevent unauthorised entry.
    Erecting a small building over the source works for extra protection.

  • Close by protection zone. Matching with determined underground flow lines of the appeal zone Removal of livestock by building a strong livestock fence - at least 5 metres away.

  • Remote protection zone. Matching with the impluvium area in which similar but less drastic measures have to implemented.

It is essential to set and equip the construction of the bore hole in regards of its own identified pumping characteristics. Over pumping will inevitably lead to serious damages such as silting up, corrosion etc. If more water is needed another drill must be envisaged or increasing water storage capacity to cover the needs.

When the catchment works are properly carried out and protected against pollutions aging is unavoidable with the consequences of drop of productivity.

Maintenance procedures will delay or restore the output yield:
  • Drilling/installation of the submersible pump etc. should be undertaken by a specialist.
  • The bore head and pipe work should be fitted with a non-return valve to prevent the siphoning of water back down the borehole.
  • Pipe work connecting the source to bottling plant should be:-
    Made of materials that are certificated for drinking water contact use.
    Fitted with a facility to isolate from the source for cleaning/disinfection purposes.
  • Maintained to remain leak free. Protected against mechanical damage (i.e. by vehicles) and freezing.
  • Regular mechanical servicing of the submersible pump, strainer etc.
  • Continuous metered survey of pumping flow will prevent from major disorders.
  • Sampling point should be available to enable water samples to be taken for analysis.

Resource quality - Watertreatment and filtration, quality checks - Bottled water