Soil investigator

‘Soil Investigator’ is a term used in common parlance. The current official term is ‘geotechnical expert’. The key tasks of a soil investigator include, in particular, carrying out site investigations, drawing up soil investigation reports and supervising construction projects.

What does a soil investigator do?

Following a review of relevant documents such as geological maps, drilling records, etc., and a site survey, the soil investigator determines the geotechnical investigations required. Geotechnical investigations encompass all the engineering-geological, hydrogeological, soil-mechanical, environmental and chemical investigations necessary for the structural assessment.

In the Soil Investigation Report, the soil investigator describes the soil structure at the site of the relevant construction project, the groundwater level, any necessary dewatering measures and the possible reuse or disposal of the excavated soil. Another important task of the soil investigator is to draw up guidelines regarding the nature and dimensions of the foundations, protective measures against waterlogged soil and the shoring of the excavation pit.

The interaction between the soil and the structure must be assessed and described by the geotechnical expert in their foundation proposal. This forms the basis for the stability and safety in use of the structure, which must also be established in the soil investigation report.

When assessing existing foundations – which is particularly important when modifying existing structures – the soil investigator is required not only to possess knowledge of soil mechanics and foundation engineering but also to carry out a correct assessment of the existing structure. For example, the acceptability of loads from old structures usually has to be assessed without any existing calculations, in order to take necessary measures and avoid unnecessary ones.

Construction often has to take place on former industrial sites or other contaminated land. In such cases, the soil investigator must specify which measures need to be taken, based on the soil mechanics and chemical investigations carried out.