Old municipal and industrial waste landfills: examples of possible application of geophysical survey techniques for assessment prior to reclamation

Further to the implicit environmental risk, abandoned municipal and industrial waste landfills frequently represent a serious problem, particularly as adequate information relating to their depth and lateral extension is either very limited or completely lacking. Moreover, knowledge of waste consistency, presence and quality of saturating fluids, metals and so on, should not be neglected when designing reclamation procedures. With the purpose of overcoming -at least partially- the abovementioned lack of information, the potential role of geophysical techniques including gravity, electrical and seismic methods, and their convenience of use, is proposed and examples provided. The first example relates to a combined application of gravity and shallow reflection geophysical methods in a mine tailings basin; in this case, the geophysical results obtained allowed the geometry and depth to the bottom of the landfill, the presence of fractures affecting the bottom and the density of disposed materials to be estimated; the second example related to application of seismic refraction tomography by means of which the structure of an old municipal waste landfill was derived; in the third example an old disposal site hosting demolition rubble was explored using the electrical resistivity tomography technique. On the whole, the convenience of applying geophysical exploration techniques for the pre-reclamation assessment of old waste landfills has been demonstrated.