Site investigation is carried out in order to determine the engineering properties of soil and rock and how they will interact with a planned development. The purpose of site investigation is to establish parameters for foundation, substructure and infrastructure design and to assess the potential geotechnical, geoenvironmental, geological and hydrological risk to humans, property and the environment.
The design and scope for each investigation will depend upon site-specific circumstances such as the anticipated geology, previous use of the site and the construction proposals. There are a variety of techniques and procedures that may be used, and each consultant may adopt a different approach for any particular project. However, it is usual for the investigation to be carried out as a phased exercise, generally comprising:
Phase 1 — desk study and reconnaissance survey
Phase 2 — intrusive investigation, sampling, analysis and report
Phase 3 — design of remediation strategy (if required)
Phase 4 — validation and monitoring of remediation during the construction works
It is essential that the information obtained from each phase is assessed to ensure that the original objectives of the site investigation are satisfied. Changes to the scope of the investigation, or even the design proposals and construction works, might be needed in the light of any unexpected findings.
The terms ‘site investigation’ and ‘ground investigation’ are frequently confused. At RSA Geotechnics we think of a site investigation as involving the collation of desk study information, appraisal of the data, assessment of the ground conditions and the provision of an interpretative report. To us, a ground investigation is generally a more restrictive phase of specialist intrusive geotechnical investigation with associated site monitoring, testing and factual or interpretative reporting.