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Drilling Process

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Step by Step Drilling Procedure

Water is one of the most important substances in the world. It is therefore very important to ensure that we can access clean water with ease. One effective way of doing this is by digging of boreholes, it is important to use the appropriate borehole drilling procedure to ensure no environmental hazards occur.

Most people have seen a borehole but very few people know the process that is taken to dig a good borehole. When drilling a borehole these are the step by step procedure used.

  • Hydrogeological Survey

    • DETAILED DESK STUDY: This is a comprehensive desk study of the general area and includes review of existing information, maps, and reports in the vicinity of the project.

    FIELD RECONNAISSANCE: Mobilize to site and carry out comprehensive mapping using resistivity methods. (Hydro geological and Geophysical Borehole site investigations and analyze all gathered information.)

    DATA ANALYSIS AND REPORTING: Compiling of a detailed survey report to include geological and hydro geological data, geological logs of surrounding boreholes and groundwater levels of surrounding boreholes.

  • Environmental Impact Assessment

    • Appraisal / Assessment for National Environmental Management Authority (NEMA) in conformity with the requirements of Environmental Management and Coordination ACT, 1999 and Environmental (Impact Assessment and Audit) Regulations, 2003.

  • Statutory Requirements
    •  Application and obtain the necessary Water Resources Management Authority (WRMA) Authorization to drill and No Objection from local Water Resources Users Association (WRUA) for the borehole drilling works where applicable.
    • Application and obtain the NEMA Licence to drill.
    • Application and obtain an Authority to drill from the local County Governments.

      TOM (1)

      Drilling Process

      1. Drilling of  a pilot hole 10’’,11” or 12’’ depending on the recommended borehole diameter & installing appropriate temporary casing to prevent caving in of the top loose formations.
      2.  Drilling to the recommended depth and diameter. We employ Down The Hole (DTH) Rotary method which is suitable for drilling through both unconsolidated material and hard compact rocks.
      3. Representative samples of the drill cuttings returned to the surface are collected at two (2) metre intervals and placed at the sample box while maintaining a log of the penetration rate on a meter by meter basis.
      4. Well design. In the process of specifying the physical materials and dimensions for the well, Maji Africa Professionals shall ensure and be guided by the following:
        • Highest yield with minimum drawdown consistent with aquifer capability.
        • Water that remains sand and silt free to protect and ensure long pump life.
        • Ensure no contamination of the water from the surrounding.
        • Reasonable short term and long term costs.
        • A well that will have a long life and be efficient in operation.
        • Conditions set out in the WRMA Authorization to drill.
      5.  Installation of Steel or UPVC Casing pipe casings as per recommendations of the hydro geological survey report.
      6. Supply and installation of gravel filter pack/formation stabilizer which will be2-4 mm diameter, 100% siliceous and well rounded ensuring a higher hydraulic conductivity.
      7. Development by air lift raw hiding into and through the aquifer zones until the water lifted is clean and clear, with electrical conductivity stable. Chemical treatment will be necessary as dictated by geological conditions.
      8. Capping of the borehole.
      9. Placing a sanitary seal for the top 6-18m either by introduction of a cement grout or bentonite seal, backfilling with approved materials and constructing a concrete plinth at the well head.
      10. Test Pumping of the well to determine the borehole yield and other aquifer characteristics.
      11. Physical, chemical and bacteriological quality analysis by an approved laboratory
      12. Records:  After completion of all works at the borehole, we shall submit to the Employer following documents:

      Records

      Borehole Completion Record as outlined in the Water Act 2002. Copies should be delivered to Ministry of Water and Irrigation Data Office to be issued with a Borehole serial number and to WRMA.

      Daily records shall include the following:

      • Site name
      • Borehole reference number
      • Method of drilling
      • Diameter of hole, depth of changes in diameter
      • Description of rocks drilled with depths of transitions encountered
      • Water strike levels
      • Records of components and additives used.
      • Pump installation which as a general rule will be designed to produce 70% of the tested yield.
      • Reticulation works
      • Obtaining an Abstraction Permit from WRMA.