Building without a site investigation in Ghana is like drilling a borehole without knowing where the water is. The ground beneath your feet determines whether your structure stands for 50 years or cracks in 5. A professional ground investigation tells you exactly what you're building on — before a single block is laid.
What Is a Site Investigation?
A site investigation (also called a ground investigation or soil investigation) is a systematic study of the ground conditions at a construction site. It combines desk-based research with physical on-site testing to produce a geotechnical report that informs foundation design, earthworks, and drainage.
In Ghana, site investigations are essential for residential buildings, commercial developments, roads, bridges, dams, and any project where ground conditions affect structural performance. Yet they remain one of the most skipped steps in Ghanaian construction — and one of the most expensive to ignore.
Types of Site Investigation in Ghana
Preliminary Site Investigation (Phase 1)
A desk study and walkover survey of the site. We review existing geological maps, aerial imagery, historical land use records, and drainage patterns to identify potential ground risks before physical investigation begins. Recommended as the first step for any project.
Detailed Site Investigation (Phase 2 / Intrusive)
Physical investigation of the ground using boreholes, trial pits, and in-situ testing. This is the standard approach for foundation design and is required by most structural engineers and lending institutions in Ghana.
Geotechnical Site Investigation
A comprehensive investigation that includes soil sampling, laboratory testing, groundwater monitoring, and a full geotechnical report with bearing capacity values, settlement predictions, and foundation recommendations.
Environmental Site Investigation
Assesses contamination risks on brownfield sites or land with a history of industrial use. Includes soil and groundwater sampling for chemical contaminants.
Geophysical Site Investigation
Uses non-invasive techniques like ground penetrating radar (GPR) and electrical resistivity to image the subsurface before physical investigation. Useful for large sites or where access is limited.
Methods Used in Ground Investigation
| Method | Best For | Depth |
|---|---|---|
| Trial pits | Shallow foundations, soil profiling | 0–5m |
| Cable percussion boreholes | Deep soil profiling, SPT testing | 5–30m+ |
| Rotary boreholes | Rock coring, deep investigations | 10–100m+ |
| Window sampling | Quick profiling in soft ground | 0–10m |
| Cone penetration test (CPT) | Continuous soil profiling | 0–30m |
| GPR investigation | Utility mapping, void detection | 0–5m |
Trial Pits — What They Are and When You Need Them
Trial pits (also called trial holes or test pits) are shallow excavations — typically 1.5–4m deep — dug by machine to expose the soil profile for direct inspection. They are the most cost-effective method for investigating shallow foundation conditions and are widely used in Ghana for residential and small commercial projects.
Trial pits allow the site investigator to:
- Visually inspect soil layers and record their thickness and characteristics
- Take disturbed and undisturbed soil samples for laboratory testing
- Identify groundwater levels and perched water tables
- Check for voids, weak zones, or buried obstructions
- Assess suitability for soakaway drainage systems
Boreholes for Site Investigation
Where trial pits can't reach — deep foundations, bridges, multi-storey buildings, or sites with high groundwater — investigation boreholes are drilled. AquaProbe drills geotechnical investigation boreholes using rotary and cable percussion methods, with standard penetration testing (SPT) at regular intervals to measure soil strength.
Geotechnical boreholes in Ghana are typically 15–30m deep for building foundations, and 30–60m+ for infrastructure projects like bridges and dams.
What a Site Investigation Report Includes
- Borehole and trial pit logs showing soil layers and depths
- Laboratory test results (particle size, Atterberg limits, compressive strength)
- Groundwater levels and fluctuation data
- Bearing capacity values for foundation design
- Settlement analysis and predictions
- Foundation type recommendations
- Earthworks and drainage recommendations
- Any contamination or environmental risk findings
Site Investigation for Different Projects in Ghana
Site investigation for building construction
Essential for any structure in Ghana. Ground conditions across Accra, Kumasi and other regions vary enormously — from soft coastal clays to hard crystalline basement rock. Without investigation, your structural engineer is guessing at your foundation design.
Site investigation for road construction
Roads in Ghana fail prematurely largely due to inadequate subgrade investigation. A proper soil investigation identifies weak or expansive soils that require treatment before road construction begins.
Site investigation for dam construction
Dam sites require the most thorough geotechnical investigation of any civil project — including geological mapping, deep boreholes, permeability testing, and seismic assessment.
Geotechnical investigation for tunnels
Tunnel investigations require continuous soil and rock profiling along the entire tunnel alignment, with particular attention to groundwater conditions and rock mass quality.
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Get my 50% off quote →Frequently Asked Questions
What is the difference between a site investigation and a ground investigation?
The terms are used interchangeably in Ghana and internationally. "Site investigation" is the broader term covering desk study, walkover survey, and intrusive investigation. "Ground investigation" typically refers specifically to the physical, intrusive phase involving boreholes and trial pits.
How much does a site investigation cost in Ghana?
Site investigation costs in Ghana depend on the number of boreholes or trial pits, required depth, laboratory testing scope, and site access. Request a quote from AquaProbe this month and save up to 50%.
Is a site investigation required by law in Ghana?
While there is no single law mandating site investigations for all projects, the Ghana Building Code, structural engineering standards, and most lending institutions require geotechnical investigation reports before approving designs or disbursing construction finance.
How long does a site investigation take in Ghana?
A simple residential site investigation (2–3 trial pits or boreholes) typically takes 1–3 days on site, with a laboratory turnaround of 1–2 weeks and report delivery within 3 weeks. Larger infrastructure investigations take longer depending on scope.
What is a preliminary site investigation?
A preliminary site investigation (Phase 1) is a desk study and walkover survey that reviews existing data — geological maps, aerial photos, historical land use — to identify potential ground hazards before physical investigation begins. It is the recommended first step for any construction project in Ghana.