A Large‐Scale Flow and Tracer Experiment in Granite: 1. Experimental Design and Flow Distribution

Abstract

This paper describes the Stripa three‐dimensional experiment where water and tracer flow has been monitored in a specially excavated drift in the Stripa mine. Several new experimental techniques and equipment were developed and used. The experiment was performed in a specially excavated drift, 100 m long, at the 360 m level in granite. The whole ceiling and the upper part of the walls were covered with 375 individual plastic sheets where the water flow into the drift could be collected. Eleven different tracers were injected at distances between 11 and 50 m from the ceiling of the drift. The flow rate and tracer monitoring was kept up for more than 2 years. The tracer breakthrough curves and flow rate distributions were used to study the flow paths, velocities, hydraulic conductivities, dispersivities and channeling effects in the rock. This paper describes the experimental techniques, the fracture mapping, the tracer and flow rate measurements and the results of the flow rate measurements. The detailed observations made possible by the plastic sheeting technique have given some qualitative as well as quantitative information on flow rate distribution in fractured rock which previously has not been available. These observations may be of importance for assessing the transport of dissolved species such as radionuclides through fractured rock.