Machine dug trial pits typically extend to 4.5m depth, provide very good visual assessment, and are cheap, quick and flexible.
Trial pits can often provide the most practical and economical method of site investigation and assessment. ESP often utilises trial pits to obtain samples and engineering logs of shallow strata and we consider the large in-situ exposure of soils to be of importance when dealing with variable ground conditions.
Some benefits of trial pits include:
- The SI enables information to be collected to further characterise the Conceptual Model (S-P-R)
- The presumed Conceptual Ground Model can be updated with actual site data in real time
- The siting can be justified and compared with assumptions reasonably developed during desk-study
- It is not limited to the collection and analysis of samples to simply ascertain contaminant concentrations – the input to engineering geology and geotechnical assessments is valuable
- The sampling strategy can be modified whilst the investigation is in progress for little cost
It is also important to consider the Health and Safety implications of trial pitting, both during and after the investigation.