Engineering geological report
The final document of the investigation: soil profile, soil parameters, groundwater and recommendations for the designer.
Licensed service · EL-845/2026
The engineering geological (geotechnical) report is the final output of the field and laboratory work. The designer sizes the foundation using the soil parameters it contains, so its structure, clarity and the justification of its values matter as much as the measurements themselves.
What an engineering geological report is
The report is a technical document made up of text, tables and drawings that describes the site geology, groundwater, soil properties and geohazards. Its key outcome is the division of the ground into engineering geological units and, for each unit, the characteristic and design values used in foundation design.
The report is not produced in isolation but as the conclusion of the investigation: its quality depends directly on where boreholes were placed, whether samples were taken without disturbance and how much laboratory testing was done. We prepare the report to the designer's technical brief and explain its findings to you and your designer.
When it is required
- for the foundation design of buildings and structures;
- as part of the design documentation for a building permit;
- for refurbishment, adding storeys or strengthening an existing building;
- when investigating the causes of structural distress;
- to plan excavation, earthworks quantities and dewatering;
- to assess whether a plot is suitable for development before purchase.
Report contents
| Section | What it covers | What the designer looks for |
|---|---|---|
| Introduction and work performed | Project, technical brief, quantities and methods | Whether the scope suits the project |
| Site setting | Topography, climate, man-made influences | Surface runoff, level differences |
| Geology | Age, origin and bedding of the soils | How layer thickness varies across the site |
| Hydrogeology | Groundwater level, regime and aggressiveness | Basement, waterproofing, dewatering |
| Soil properties | Engineering geological units and their parameters | Design values for foundation calculations |
| Problem soils and geohazards | Made ground, collapsible, swelling and saline soils; landslides, groundwater flooding, erosion | Whether additional measures are needed |
| Seismic conditions | Ground category by seismic properties | Input for seismic design |
| Conclusions and recommendations | Summary of findings | Foundation type, bearing stratum, protective measures |
Drawings and tables
- exploratory hole location plan — boreholes, trial pits and probing points on the topographic plan;
- geological cross-sections — how the units run between boreholes, and the groundwater level;
- borehole logs — layer descriptions, sampling depths and water levels for each hole;
- probing plots — soil resistance against depth;
- laboratory summary sheets — results for each sample, oedometer and shear test plots;
- water chemical analysis and the aggressiveness assessment.
How to read the report
- Find the foundation level on the cross-section and see which engineering geological unit it falls in.
- Check the design values for that unit: density, deformation modulus, angle of internal friction, cohesion and, for clays, the liquidity index.
- Check whether a weaker layer lies below foundation level — it governs the settlement calculation.
- Find the encountered and stabilised groundwater levels and any note on seasonal rise.
- Read the section on problem soils and geohazards — collapsibility, swelling, salinity, aggressiveness.
- Compare the recommendations with the design solution and raise questions where they differ.
What matters to the designer
- Borehole depth. Boreholes must cover the zone of influence of the foundation; a report based on shallow holes is not adequate for deep or piled foundations.
- Justified parameters. The number of tests should be stated for each unit; values based on only a few tests should be used with caution.
- Date of water level readings. The level depends on the season, so the reading date and a note on seasonal variation are important.
- Consistency with the design. If the building position, footprint or foundation depth has changed, the adequacy of the existing report must be reassessed.
How the work is carried out
- Preparation. Agreeing the technical brief and work programme, collecting archive data.
- Field work. Drilling, sampling, probing and groundwater measurement.
- Laboratory. Testing of soil and water samples.
- Office processing. Defining units, statistical processing of parameters, drawing sections, writing the text and internal checking.
- Handover. Issue of the report and answers to the designer's questions.
Equipment and software
- drilling and probing rigs — to obtain field data;
- laboratory equipment — for physical and mechanical soil tests;
- survey instruments — to determine coordinates and levels of exploratory holes;
- CAD and specialist geological software — for sections, logs and summary tables.
Deliverables
- the report in PDF and signed hard copies in the agreed number;
- drawings in DWG where required;
- laboratory test certificates.
Timing
- the volume of field work and borehole depth;
- the laboratory schedule — oedometer and shear tests take longer;
- geological complexity of the site and the presence of problem soils.
What we need from you
- the designer's technical brief or project details: number of storeys, basement, approximate foundation depth;
- a plan showing the building on the site and a topographic plan;
- any previous investigation data.
What affects the price
- the volume of field and laboratory work;
- additional requirements for the report — seismic or hydrogeological sections, geohazard assessment.
Indicative rates are on the engineering geological survey prices page; you can send a quote request for your project.
