Stage 2 Investigations – Why we need to go to the next step.


“I just want to know; is my site contaminated? Can I push on with my project?” are questions we’re asked all too often at SESL. Answering this is often not so simple.

No two contaminated site investigations are ever the same. To account for this, investigation requires a staged assessment approach to ensure that the human and environmental health risks, as well as our clients’ commercial risks, are managed.

In Australia, contaminated site investigations are undertaken in accordance with the National Environment Protection (Assessment of Site Contamination) Measure (NEPM) 1999 (NEPC, 2013). This outlines a tiered approach to all assessments, ensuring the highest likelihood of risk identification and the implementation of the best management practices.

The initial stage is a Preliminary Site Investigation (PSI). It is designed to identify whether there is potential for contamination to exist on a site. A PSI will often identify a number of data gaps that will need further investigation to address. The second stage, a Detailed Site Investigation (DSI) is required when the PSI identifies potential or actual contamination that requires further assessment and delineation to enable management strategies to be devised.

The way that SESL stages (breaks up) a DSI is often influenced by the findings of the PSI as well as site access issues (e.g. sampling limitations prior to demolition), the incoming investigation results (e.g. clean areas, hotspots, etc.) and the needs of the client. The information obtained during the DSI allows data gaps to be reduced, conceptual site models to be refined to be reflective of actual risks and provide information to feed into Site-Specific Health and Environmental Risk Assessments and remediation design.

While a staged approach may take a little longer in the short term, it reduces uncertainty and can lead to significant time and cost saving in the remediation phase. It is the methodology required by local, state and national regulators and is always SESL’s preferred method of assessment.