Classification and characterisation of water-conducting features at Aespoe

The objectives of the Fracture Classification and Characterization Project (FCC), a joint undertaking of Nagra (Switzerland) and SKB (Sweden), are - to classify water-conducting features that occur in the Aespoe tunnel system, - to characterize and conceptualize these features with respect to radionuclide transport properties (e.g. structure, mineralogy, distribution of flow and matrix porosity), - to develop and apply a methodology for the characterization of water-conducting features in crystalline rocks. The methodology of investigation includes a stepwise procedure: - Compilation of an inventory of existing data (geology, hydrogeology, hydro-chemistry) and of the boundary conditions on how water-conducting features can be explored (e.g. boreholes, open tunnel). Definition of scale at which the investigation should target. - Preliminary characterization of a limited number of typical water-conducting features, with the objective to understand the processes that governed the evolution of water-conducting features and so to define a set of geologic parameters that adequately describe the features. - Full characterization of a large number of water-conducting features and acquisition of a database containing all relevant parameters that can be observed or measured. - Database analysis (which parameters are common to all features, which vary systematically) and derivation of a fracture classification scheme. - Derivation of simplified conceptual models of all types of water-conducting features, including geometric and lithologic (mineralogic, porosimetric) information needed for transport modelling. - Transport modelling and sensitivity analysis of parameters from the conceptual models.