From theory to the complex geospatial ground-truth of contaminated soils

Characterization and subsequent reclamation of contaminated sites require detailed knowledge of the geospatial distribution of contamination. In Italy, a potentially contaminated site is an area where the concentration of one or more contaminants in soils is above land-use legal limits (CSC according to Italian law 152/06). Four main phases have to be followed to assess contamination and then reclamation: 1) preliminary conceptual model, 2) characterization plan, 3) site specific risk analysis (by Risk-net software) setting the contamination threshold concentration (CSR), 4) assessment of contamination and therefore reclamation action by comparison between CSC and CSR. The geospatial distribution of contaminants is considered in the characterization plan. It is mandatory to sample at least three samples for each surveyed point (one sample in the 0 to 1 m depth, one sample in the capillary fringe zone and one in between). There aren't clear indications on the sampling strategy and spatial density. According to Italian law (D.M. 471/99), it is usual to identify 5 to 15 sampling points for areas of 1 to 5 hectares. In this work we attempt to answer the question: "After more than a decade from the introduction of law 152/06 and considering the progress of scientific knowledge, are these soil sampling criteria suitable for assessing the spatial and volumetric distribution of site contamination?".