The Enhanced Sealing Project (ESP) at the Underground Research Laboratory in Canada: Sixteen Years and Counting?

Abstract

Abstract Established in 2008, the Enhanced Sealing Project (ESP) was the final full-scale experiment at the Underground Research Laboratory (URL) in Manitoba, Canada. As of January 2023, the project has been monitoring the evolution and performance of the full-scale composite shaft seal at the URL for over 16 years. The shaft seal was constructed in a 5-m-diameter circular shaft across a water bearing fracture zone at the depth of c. 270 m and comprises of 6-m-thick clay component that is sandwiched between two 3-m-thick concrete components. The clay component was made of 40% (by dry mass) of bentonite and 60% of fine aggregate mixture. This paper highlights the ESP results until early 2023. The ESP results, combined with the URL results from 1980s to 2013, provide 45+ years of unique data sets representing a lifecycle of an underground facility from pre-construction, operation, decommissioning, closure, and post-closure phases. This paper also examines the feasibility of the ESP extension beyond 2023 and proposes additional efforts that will enable to observe the evolution of the seal and URL for the longer term (e.g., several decades).