Atomic Energy of Canada Limited’s Underground Research Laboratory was built to allow study of concepts for the long-term disposal of Canada’s used nuclear fuel in a deep geological repository. The underground portion of the facility was decommissioned and permanently closed in 2010.

Decommissioning included the installation of a seal at the intersection of the access shaft with a hydraulically active fracture zone located at 275 m depth. The objective of the shaft seal is to limit potential groundwater mixing above and below the fracture zone.

This project provided a unique opportunity to study the hydro-mechanical evolution of a full-scale shaft seal installed under conditions similar to those in a deep geological repository.

This thesis provides an overview of the instrumentation and data logging techniques that have been successfully used to monitor the initial behaviour of the shaft seal in this unique underground environment.