A tiered approach to natural background level (nbl) assessment in groundwater under a non hazardous waste land fill in Latium region (Italy)

This paper deals with the results of investigation and monitoring activity on groundwater flowing under an area of a non hazardous waste landfill, placed in the Agro Romano, in the South Rome town area, near to Colli Albani Volcanic region. The geological framework is mainly dominated by pyroclastic deposits of Colli Albani Volcanic Complex named pozzolanelle and tufo lionato. The purpose of the study has been the investigation of the origin of concentration values referred to Arsenic, Manganese, and Fluoride, exceeding the European law limit values. In order to identify whether the observed concentrations represent a naturally-occurring condition or they are due to an anthropogenic source, it was applied a tiered up approach. As a matter of fact in the aim of following a tiered approach, they were analyzed, different aspects like: the impacts coming from anthropogenic activities, regional and site specific geology knowledge, the mineralogic properties of the geological outcrops, site specific geochemistry, statistical approach. Carrying on a background analysis early may become an important guideline for statutory requirements in the site assessment based on legal fixed concentrations.