Summary of the Fracture Zone 3 Groundwater Tracer Test Program at the Underground Research Laboratory

Résumé du livre

A series of groundwater tracer tests was conducted within fracture zone 3 (fz3) at aecl's underground research laboratory (url) as part of the transport in highly fractured rock experiment. four tracer tests were performed in the radial convergent groundwater flow field in fz3 at distances ranging from about 60 m to 160 m from the url shafts. tracers were injected into the radially converging groundwater flow field surrounding the url shafts and collected at groundwater seepage locations in the main and ventilation shafts of the url. a conceptual model of solute transport has been developed for the groundwater flow system of the upper 200 m of rock at the url. within the region of drawdown created by the excavation and subsequent seepage of groundwater to the url shafts, tracer transport occurs within fz3 as well as the network of permeable subvertical fractures surrounding fz3. several factors control the rate of tracer transport to the url shafts. these include, but are not limited to: in the near-field (within a radius of about 80 m of the shafts) transport is very rapid and occurs primarily within the network of permeable subvertical fractures underlying fz3; in the far field (at distances ranging from about 100 m to 160 m from the shafts) transport occurs within fz3 and/or the network of permeable subvertical fractures underlying fz3 and is greatly controlled by permeability variations within fz3, particularly regions of low permeability; and flow channelling and/or multiple groundwater flow pathways within the permeable fracture play an important role in tracer transport to the url shafts at these distance scales.