Combining Geophysical, Geochemical and Geostatistical Methods to Detect Contamination Anomalies in a Controlled Dump in Oporto, N Portugal

The characterization and environmental monitoring of Municipal Solid Waste (MSW) deposits are an increasing area, in terms of the interdisciplinary studies involved. Whatever the solution adopted for the MSW treatment, its final containment on landfill is not the end of the problem. Rather, the need for continuous monitoring, tracking the evolution of the waste mass in all its surroundings, will contribute to evaluate the environmental consequences of the existence of a deposit of MSW. The assessment of contaminants dispersion in Controlled Dumps (CD) of MSW is possible through the combination of geophysical, geochemical and geostatistical methods as described in this paper. The methodology applied in this study will contribute to evaluate the environmental consequences of the Matosinhos CD (N Portugal), which is set in a granitic crystalline geological context with a permeability controlled by differential weathering associated with fracturing. The statistical methods here described (Lepeltier, 1969; Matschullat et al. 2000), more commonly applied to geochemical data, were adapted to be used with our set of 2D resistivity profiles in order to relate them and thus delineate the contamination anomalies in the CD surroundings. Groundwater samples were collected in piezometers, upstream and downstream of the CD, with the aim of directly confirming the presence of contaminants indirectly detected by the geophysical and geostatistical methods. The combination of these different approaches allows an approach towards the detection and delineation of contaminant plumes from these deposits.