This is the second stage of investigation, where the results of the PSI outline a requirement for a further investigation. This is typically performed to confirm the presence/absence of contaminants in the property and generally involves intrusive works such as drilling of soil bores and installation of monitoring wells and soil vapour bores (if found required) or test pitting and collection and analysis of soil, groundwater or vapour.

The results of this investigation are compared to National Environment Protection Measure (NEPM) 2013 and other relevant guidelines to confirm if the current site condition is protective of both the environment and/or human health. Depending on the outcome of detailed site investigation, further investigation maybe required and may also lead to preparing a Contaminant Fate and Transport Modelling and Human Health and Environmental Risk Assessment.