8Stages of investigation

8 Stages of investigation

Schedule A shows the staged site assessment process indicating which general guidelines are applied to preliminary and detailed site investigations. The preliminary investigation usually involves: (a) establishing a site history to identify the characteristics of the site (such as the location and layout of the site, the building construction on the site, the geological setting, current and past activities at the site, current and past uses of the site, and heritage considerations); and (b) inspecting the site; and (c) interviewing representatives for the site. Investigations are usually confined to areas where potentially contaminating activities have occurred and involve a site history-based sampling plan. The preliminary investigation and initial assessment of site contamination should consider the possibility of all forms of potential contamination based on past land use. The preliminary investigation should be sufficient to identify whether contamination exists on the site. Contamination may not be completely delineated at this stage. A detailed investigation is required when the results of preliminary investigation are insufficient to enable site management strategies to be devised. Potential or actual contamination will need further evaluation. Potential contamination may have been indicated by the presence of unexpected underground structures (eg. underground fuel or chemical storage tanks) or by the presence of imported fill (eg. ash, odorous material or various types of refuse) or staining of soil. Actual contamination may have been detected in the form of contaminants which are not naturally occurring or as elements or compounds which are above background levels or exceed the applicable investigation or screening levels. Depending on the proposed use and the results of initial site history investigations, the assessment of a site may involve both preliminary and detailed investigations. Many site investigations proceed in multiple stages due to the complexity of the site and the discovery of unexpected contamination, or as investigation funds become available. Site investigators should obtain and consider all site information available to minimise the number of site visits and costs associated with the mobilisation of field investigation teams.