BOREHOLE DRILLING

Groundwater is undeniably an important freshwater resource for drinking water supply, irrigation and industry, in addition to its natural role of sustaining river flow and aquatic ecosystems. Sustainable groundwater development is fundamental in order to provide universal access to safe drinking water.

Constructing, or repairing, boreholes requires specialized knowledge and technical expertise, and if they are not properly sited, designed and constructed in the first place, supplies cannot be maintained, and investments are wasted. And in the longer term, if groundwater resources are not effectively managed, there is risk of over-abstraction and pollution and massive failure of drinking water supplies. This cannot be allowed to happen, and which is why we are here to assist our clients in ensuring the proper process are followed in all stages of the drilling process.

Borehole drilling involves 4 steps:

1.

Geophysical Survey (Borehole Siting)

A geohydrological / geophysical is an essential step in understanding groundwater resources and siting new water boreholes. Choosing a borehole site is a critical part of the process of providing a safe and reliable supply of groundwater. The best sites are those in which catchment (natural water input) may be maximized.

Methods we use:

  • Resistivity method
  • Electromagnetic method
  • Electro-seismic method
  • Magnetic method

2.

Borehole Drilling

Once a suitable site has been selected and borehole drilling decided on, the proper drilling method must be chosen. The actual borehole is drilled using an automated Drill Rig and 21 Bar Compressor, with the method determined by the geological conditions on site.

We mainly use 2 methods:

  • Percussion drilling
  • Rotary percussion

Once drilled, permanent steel casing (see image below) will be installed from surface through unstable, unconsolidated or fractured materials usually occurring in the near surface.

3.

Pump Testing and Water Quality Analysis

Aquifer testing (4hr stepped, 24hr discharge, 24hr constant, and recovery monitoring) will be performed on each borehole, in order to determine the aquifer parameters (amount of water available) to enable proper equipping of the borehole with a pump. The results of this test will determine how much water is available for abstraction without an adverse effect on the regional groundwater.

During the aquifer test, a sample of water will be collected from each borehole for testing according to SANS 241 drinking water standards. Tests will be done at a SANAS accredited laboratory.

4.

Borehole Equipping & Registration

After successful drilling of borehole, it will be equipped with any of the below, depending on the clients’ request:

  • Pumps
    • Submersible pump and motor
    • Solar pumps
    • Hand pumps
    • Pressure booster pumps
  • Tank
    • Eco tanks, Jojo tanks, Roto tanks up to 60 000 litres
    • Vertical, horizontal and troughs
  • Tank stands
    • Galvanized steel/ pressed steel
    • Concrete base/plinth
    • Borehole protection
    • Pump houses, lockable manholes etc.
  • All plumbing and related excavations and connections.
  • Electrical connections and compliance certificate
  • Borehole registration with the Dept of Water Affairs’ National Groundwater Archives (NGA)