Ghana loses billions of cedis every year to buildings that crack, roads that fail, and infrastructure that sinks — almost always because nobody investigated the ground first. Geotechnical investigation is the science of understanding what's underground before you build on it. It's not optional. It's the foundation of everything else.
What Is Geotechnical Investigation?
Geotechnical investigation (also called geotechnical site investigation or ground investigation) is the process of characterising the physical and mechanical properties of soil and rock at a site for engineering purposes. It combines field investigation — boreholes, trial pits, in-situ tests — with laboratory analysis to produce a geotechnical report used by structural engineers for foundation design.
Geotechnical Investigation for Different Projects in Ghana
🏠 Residential buildings
Trial pits and shallow boreholes to determine foundation depth, bearing capacity, and groundwater level for houses, apartments and compounds.
🏢 Commercial developments
Multiple boreholes with SPT testing and lab analysis for multi-storey commercial buildings, hotels, and shopping centres.
🛣️ Roads & highways
Subgrade investigation along road alignments to identify weak soils, expansive clays, and areas requiring stabilisation before pavement construction.
🌊 Dams & reservoirs
Extensive investigation including deep boreholes, permeability testing, and seismic assessment for dam safety and design.
🌉 Bridges
Deep boreholes at each pier location to determine pile length and bearing capacity for bridge foundations.
🚇 Tunnels
Continuous profiling along tunnel alignment including rock quality designation (RQD) for tunnel support design.
Key Tests in Geotechnical Investigation
Standard Penetration Test (SPT)
The most widely used in-situ test in Ghana. A split-spoon sampler is driven into the soil at the base of a borehole by a standard weight dropped from a standard height. The number of blows required (N-value) directly indicates soil strength and is used for bearing capacity calculations and pile design.
Soil laboratory testing
Soil samples taken from boreholes and trial pits are tested in the laboratory for particle size distribution, moisture content, Atterberg limits (plasticity), compressive strength, and consolidation characteristics. These tests are essential for accurate foundation design.
Permeability testing
Measures how quickly water moves through the soil — essential for drainage design, dam core material selection, and soakaway system design.
Rock core analysis
For sites underlain by rock, rotary drilling recovers rock cores which are logged for rock type, fracture frequency, weathering grade, and strength. Rock Quality Designation (RQD) is calculated to guide foundation and tunnel design.
Why Geotechnical Investigation Fails in Ghana
Unfortunately, inadequate geotechnical investigation is extremely common in Ghana. The most frequent causes of failure are:
- Skipping investigation entirely to save upfront cost — the most expensive mistake
- Too few boreholes or trial pits for the site area — missing critical soil variations
- Boreholes not deep enough to reach the relevant founding stratum
- No laboratory testing — field description alone is not sufficient for design
- Reports prepared by unqualified persons without proper equipment
AquaProbe uses calibrated equipment, CSIR-accredited laboratory testing, and qualified geotechnical engineers to ensure every investigation meets the standard your project deserves.
What's in a Geotechnical Investigation Report
- Site description and location plan
- Borehole and trial pit logs with full soil descriptions
- SPT N-values and in-situ test data
- Laboratory test results and interpretation
- Groundwater levels and seasonality
- Bearing capacity and settlement analysis
- Foundation type and depth recommendations
- Earthworks and drainage recommendations
- Any contamination findings
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Get my 50% off quote →Frequently Asked Questions
What is the difference between geotechnical investigation and site investigation?
Geotechnical investigation focuses specifically on the engineering properties of soil and rock for structural design purposes. Site investigation is the broader term that also includes environmental assessment, contaminated land investigation, and services mapping. Geotechnical investigation is always a component of a full site investigation.
How much does geotechnical investigation cost in Ghana?
Costs depend on the number of boreholes, trial pits, depth, lab testing scope, and project type. Request a quote from AquaProbe this month and save up to 50%.
Who carries out geotechnical investigations in Ghana?
Geotechnical investigations should be carried out by qualified geotechnical engineers or engineering geologists with appropriate drilling equipment and access to accredited laboratory testing facilities. AquaProbe Ghana provides fully qualified geotechnical investigation services across all 16 regions.
Is geotechnical investigation required for all buildings in Ghana?
The Ghana Building Code and structural engineering practice require geotechnical data for structural design. Most reputable structural engineers will not produce a foundation design without investigation data. Banks and mortgage institutions in Ghana increasingly require geotechnical reports before approving construction finance.