An above ground hard rock test site was isolated in a quarry and thoroughly examined for its distribution of fractures and sedimentary features to establish an in situ test site with excellent conditions to study transport processes in fractured porous media. The data were used to generate a stochastic fracture network model. For a first characterization of mass transport parameters, gas tracer testing was conducted in the unsaturated system. Tracers applied were Helium and Sulfur Hexafluoride. The resulting tracer breakthrough curves were fitted using least square algorithms of analytical solutions to the standard Advection Dispersion Model (ADM) and to the Single Fissure Dispersion Model (SFDM). The -1.5 slope criterion for the log-log plot of tailing data was investigated for applicability to gas tracer data and was found to be a reliable dicision tool for the occurance of matrix diffusion in unsaturated naturally fractured porous media. Limitations to estimating hydraulic parameters in fissured rocks due to the simplifications of the transport processes, which have to be accepted when applying analytical solution algorithms to gas tracer test results, are outlined.
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