Italian legislation provides for a specific procedure pursuant to Article 242 of Legislative Decree 152/06 and subsequent amendments in the event of possible contamination of environmental matrices, in order to identify the extent of the pollution and corrective actions.
Whether an event that could lead to contamination at any site is detected, a distinction must be made in the first stage:
potentially polluted sites;
actually contaminated sites.

This distinction is made on the basis of the results of specific sampling and analysis of environmental matrices, and through the processing of all available data and those specifically obtained, in accordance with the times and methods provided for by the legislation on remediation (art. 242 et seq. of Legislative Decree 152/06 et seq.). Environmental matrices are defined as soil, subsoil and groundwater, which are considered, if contaminated, as secondary sources of pollution.
Pursuant to art. 240 of Legislative Decree 152/06 and subsequent amendments, a potentially contaminated site is defined as a site where one or more concentration values of the polluting substances detected in the environmental matrices are higher than the Contamination Threshold Concentration (CTC) values, expressly defined by the regulations on the basis of their intended use (residential or industrial/commercial). A site can be defined as potentially polluted, following an appropriate “preliminary investigation”. Exceeding the CTCs alone is not sufficient to determine whether a site is contaminated, but requires further investigation at the site: the site characterisation plan and specific site risk analysis will be produced.
A site is contaminated only if the values of the Risk Threshold Concentrations (RTC) determined by the application of the risk analysis procedure, on the basis of the results of the characterisation plan, are lower than the concentrations of the pollutants found at the site. RTCs are determined on a case-by-case basis by considering and processing data on the environmental characteristics of the site (geology, climate, surface impermeability, etc.) and on the characteristics of pollutants (toxicity, migration routes, etc.). The concentration levels thus defined constitute the levels of acceptability of the pollutants for the specific site considered and are normally different from the CTCs.