Job Description – Field Geologist

Position: Field Geologist – Geotechnical Investigation
Department: Geotechnical Department
Location: Guinea
Reporting To: Geotechnical Engineer / Geotechnical Manager

Job Summary

We are looking for an experienced Field Geologist to support and supervise geotechnical investigation activities on site. The candidate will be responsible for managing drilling crews, supervising borehole drilling, carrying out detailed geological and geotechnical logging, conducting field tests, collecting and managing samples, and installing groundwater monitoring instruments such as piezometers.

The ideal candidate should be a practical, site-oriented professional with good knowledge of drilling operations, soil and rock identification, SPT, sampling, permeability testing, groundwater monitoring, and geotechnical investigation procedures.

Key Responsibilities

1. Drilling Supervision

• Supervise daily drilling activities and coordinate with drillers, operators, and site technicians.
• Ensure drilling is carried out according to the approved investigation program and technical requirements.
• Monitor drilling depth, drilling progress, casing installation, borehole stability, and groundwater conditions.
• Ensure SPT testing is conducted at the required depths and that results are properly recorded.
• Ensure proper collection of disturbed and undisturbed soil samples.
• Supervise rock coring activities, where applicable, including core recovery and RQD measurements.
• Monitor drilling equipment and immediately report technical or operational issues.
• Coordinate the daily work program with the Geotechnical Engineer and site team.

2. Borehole Logging

• Prepare accurate and detailed soil and rock borehole logs during drilling (BS or ASTM Standards)
• Identify and describe soil and rock strata based on field observations and sampling.
• Record:
  • Soil/rock classification
  • Color and consistency/density
  • Moisture condition
  • Soil stratification
  • SPT results
  • Sample depths
  • Groundwater levels
  • Rock recovery and RQD
  • Weathering and fracturing of rock
  • Any unusual or critical ground conditions
• Ensure borehole logs are updated continuously during drilling and are supported by appropriate photographs.
• Identify changes in ground conditions and immediately communicate significant findings to the Geotechnical Engineer.

3. Field Testing

Carry out and supervise geotechnical field tests as required by the investigation program, including:

• Standard Penetration Tests (SPT)
• Permeability/in-situ hydraulic conductivity tests, including appropriate borehole methods such as Lugeon or Lefranc testing, depending on soil/rock conditions and project requirements.
• Groundwater level measurements.
• In-situ infiltration or other field tests as specified.
• Field sampling and groundwater sampling where required.
• Ensure all test results are properly recorded with the relevant depth, test conditions, equipment details, and observations.

4. Piezometer Installation

• Install piezometers and groundwater monitoring instruments in accordance with the approved technical requirements.
• Select and prepare the appropriate installation depth and screened interval.
• Ensure proper installation of:
  • Screen/filter section
  • Filter sand
  • Bentonite seal
  • Backfill/grout
  • Protective surface casing and cover
• Verify the installation depth and configuration.
• Record the piezometer installation details accurately.
• Conduct initial groundwater measurements after installation.
• Coordinate subsequent groundwater monitoring and readings as required.
• Report any abnormal groundwater conditions or artesian pressure immediately.

5. Sampling & Sample Management

• Ensure samples are properly collected, labeled, sealed, preserved, and transported to the laboratory.
• Maintain proper sample identification and chain of custody.
• Ensure representative samples are obtained from all relevant soil and rock strata.
• Coordinate with the laboratory regarding sample requirements and testing priorities.
• Ensure core boxes and soil samples are properly organized and photographed.

6. Site Records & Reporting

• Prepare daily drilling and investigation reports.
• Maintain accurate records of:
  • Borehole coordinates
  • Drilling depth
  • Drilling progress
  • SPT results
  • Sample recovery
  • Groundwater levels
  • Field test results
  • Piezometer installation
  • Equipment and manpower
  • Site conditions and observations
• Take and organize photographs of drilling operations, samples, SPTs, cores, field tests, and completed installations.
• Submit daily reports and updated borehole logs to the Geotechnical Engineer/Manager.
• Highlight any technical problems, unexpected ground conditions, or deviations from the investigation program.

Team Supervision

• Lead and supervise the drilling crew during daily operations.
• Assign tasks to drilling operators and site technicians.
• Monitor the quality and productivity of the drilling team.
• Ensure that drilling and testing activities are performed safely and correctly.
• Coordinate manpower, equipment, materials, water, casing, drilling tools, and other site requirements.
• Ensure compliance with project HSE procedures and site rules.

Qualifications & Experience

• Bachelor's degree or diploma in Geology, Engineering Geology, Geotechnical Engineering, or a related field.
• Minimum 3–5 years of practical experience in geological/geotechnical site investigation.
• Strong hands-on experience in:
  • Geotechnical drilling
  • Borehole logging
  • SPT
  • Soil and rock identification
  • Soil and rock sampling
  • Permeability testing
  • Groundwater investigation
  • Piezometer installation
• Experience working with rotary drilling rigs and geotechnical investigation equipment.
• Ability to supervise drilling crews independently.
• Ability to work long periods on construction/investigation sites and travel to different project locations.
• Good knowledge of geotechnical investigation procedures and relevant standards.
• Good communication and reporting skills.
• Good computer skills, particularly MS Word and Excel.

Preferred Skills

• Experience with Lefranc, Lugeon, packer, and other in-situ permeability/hydraulic conductivity tests.
• Experience with groundwater monitoring and piezometer installations.
• Experience with rock coring, core logging, and RQD determination.
• Familiarity with ASTM, BS/EN, AASHTO, or project-specific investigation standards.
• Ability to read borehole plans, geological maps, drawings, and KMZ coordinates.
• Experience working on road, bridge, marine, foundation, or infrastructure projects is an advantage.
• French-speaking ability is an advantage.

Key Competencies

• Strong practical field skills.
• Good geological and geotechnical judgment.
• Ability to manage drilling crews effectively.
• Accurate and disciplined approach to logging and documentation.
• Good understanding of field testing procedures.
• Ability to identify and report abnormal ground and groundwater conditions.
• Strong commitment to safety and quality.
• Ability to work independently and under project deadlines.

Main Objective of the Position

The Field Geologist is responsible for ensuring that the drilling, logging, field testing, sampling, groundwater investigation, and piezometer installation are performed correctly and that reliable, complete, and technically acceptable field data are delivered to the Geotechnical Engineering team for design and reporting.