Monitoring Hydrogeological Conditions in Fractured Rock at the Site of Canada's Underground Research Laboratory

摘要

Atomic Energy of Canada Limited is constructing an Underground Research Laboratory (URL) at a depth of 250 m in a plutonic rock body near Lac du Bonnet, Manitoba. The facility is being constructed to carry out a variety of in situ geotechnical experiments as part of the Canadian Nuclear Fuel Waste Management Program. A unique feature of the URL, in comparison to other similar facilities such as the Stripa Mine in Sweden, is that it is to be constructed below the groundwater table in a previously undisturbed plutonic rock body. One of the main research objectives of the project is to develop and validate comprehensive three-dimensional models of the hydrogeology of the rock mass encompassing the URL site. Measurements made in an array of boreholes extending to depths of 1000 m on the 4.8-km exp 2 study area have established that the permeability distribution in three major extensive subhorizontal fracture zones controls the movement of groundwater within the rock mass. An automated, electronic, piezometric pressure-monitoring system has been designed to collect continuous measurements from 75 isolated hydrogeological monitoring positions within the rock mass. Piezometric data have been collected from this monitoring network to establish baseline conditions prior to any excavation into the rock mass. These data have also been used to determine the steady-state, three-dimensional, groundwater flow regimes that exist at the URL site under natural conditions. (Atomindex citation 15:072122)