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A geologic preliminary investigation is a survey of the subsoil conducted by an
engineering geologist An engineering geologist is a geologist trained in the discipline of engineering geology. Many organizations and governments have programs for the qualification, testing and certification of engineering geologists as a protection to the public.
E ...
in conjunction with a
civil engineer
A civil engineer is a person who practices civil engineering – the application of planning, designing, constructing, maintaining, and operating infrastructure while protecting the public and environmental health, as well as improving existing i ...
. Typically, the footprint of the structure is established on the proposed building site and trenches up to fourteen feet deep are dug both outside, and more importantly, inside, the proposed footprint using the bucket-end of a backhoe. In extreme cases, a larger, more powerful tracked excavator is used. The
geologist
A geologist is a scientist who studies the solid, liquid, and gaseous matter that constitutes Earth and other terrestrial planets, as well as the processes that shape them. Geologists usually study geology, earth science, or geophysics, alt ...
is looking for potential failure planes, expansive
clays, excessive moisture, potential for proper compaction, and other variables that go into the construction of a solid
foundation (such as potential for
liquefaction
In materials science, liquefaction is a process that generates a liquid from a solid or a gas or that generates a non-liquid phase which behaves in accordance with fluid dynamics.
It occurs both naturally and artificially. As an example of t ...
). Materials are also gathered to determine the maximum compaction value (a "proctor") of the subsurface. Prelims should always be conducted prior to the construction of any permanent structure.
Building engineering
Geotechnical investigations