Open Collections

Beta and Skeeter Lake Tailings Dams : Progressive Dam Safety Review Approach for the Abandoned and Remote Bullmoose Mine in NWT

Tailings and Mine Waste Conference (2023 : Vancouver, B.C.); University of British Columbia. Norman B. Keevil Institute of Mining Engineering

The Bullmoose Mine is located 80 km to the east of Yellowknife, Northwest Territories, Canada. Active mining was carried out between 1939 and 1988. Since mining was abandoned due to owner insolvency, the mine site was inherited by the Federal Government of Canada, including two separate tailings containment areas, Beta Lake and Skeeter Lake. Since 2017, Stantec had a mandate to assess the tailings facility conditions and develop mitigations to advance the site towards closure. Assessments included information review, Dam Safety Inspections (DSIs), and Dam Safety Review (DSR), among others. Information review determined that there was a lack of design and as-built documentation, dams were not properly classified, and a dam safety management system was not in place. Because of the lack of available information and site access issues, a full-scale DSR was not immediately possible. Therefore, to assess the dams’ safety, Stantec performed a comprehensive DSI and identified visible deficiencies and non-conformances that were used to guide development of prioritized recommendations to mitigate risk. This included: dam break analyses, dam reclassification, and failure mode effects analysis workshops completed in 2021, and freeboard analysis completed in 2022. A comprehensive field investigation was also carried out in 2022 to characterize the dams’ foundations. An automated instrumentation monitoring system was installed, which included vibrating wire piezometers and global navigation satellite sensors. An OMS manual was developed to guide future dam risk management. A DSR will be completed in 2023/2024, and an EPRP will be developed thereafter. Despite challenges due to the lack of historical data, as well as the remoteness of the site and short access season (two months) the project continues to advance to achieve goals using careful planning, prioritization, and a patient, systematic approach.

Text

2023-12-08

Attribution-NonCommercialNoDerivatives 4.0 International

http://hdl.handle.net/2429/86806

Unreviewed

http://creativecommons.org/licenses/by-nc-nd/4.0/