Author Description

Studies conducted during the construction of the Underground Research Laboratory indicated an excavation damage zone adjacent to an underground test tunnel driven at a depth corresponding to that of a proposed underground nuclear fuel waste disposal vault. It is expected that such a zone would have hydraulic properties different from those of the undisturbed rock mass, such that the zone might provide new pathways for groundwater flow or contaminant transport from a disposal vault. This report describes a study that used an iodide tracer to characterize the solute transport properties (permeability, transport porosity, and dispersivity) within the intensely fractured part of the excavation damage zone. The experiment was performed by continuously injecting tracer into a region of the zone and monitoring tracer breakthrough 1.5 metres away. An equivalent porous media approach was taken in analyzing fluid flow and solute transport through the zone.