Engineers Australia

The hidden cost of geotechnical investigations

Peter V. Andrews


This paper presents the results of an analysis of 201 geotechnical reports prepared by most of the geotechnical consultants in Sydney. The analysis considers the recommendations for several important design parameters in the most common soils and rocks in the Sydney Basin and compares them against a level of Geotechnical Investigation Risk. The results of the analysis are used to demonstrate that investigations with a small scope of works result in conservative design and expensive construction – the hidden cost of low levels of investigation.