Dam Safety Inspections
Under Part 10.5.3 of the Health, Safety and Reclamation Code for Mines in British Columbia, permitted mines are required to submit annual Dam Safety Inspections (DSIs).
A DSI typically involves a visit to the mine, interviews with the facility inspector and operators, visual inspections of the facilities, and reviews of available instrumentation and monitoring data. The annual DSI report should review operation, maintenance and surveillance of the tailings storage facility (TSF).
On August 18, 2014, the Chief Inspector of Mines ordered that:
- The deadline for 2014 DSIs be accelerated from March 31, 2015 to December 1, 2014;
- Those inspections be reviewed by an independent, qualified, third-party professional engineer from a firm not associated with the TSF;
- The dam’s consequence classification be reviewed by a third party; and,
- For dams with a consequence classification of high, very high or extreme: the Emergency Preparedness and Response Plans (EPRP) be reviewed, tested and updated as required.
The third-party reviews were to include the reviewer’s comments on the overall condition and consequence classification of the dams as well as the reviewer’s recommendations to improve the overall safety of the TSF.
All mines with High to Extreme consequence classifications conducted a Dam Break Inundation Study, and updated and tested their Emergency Preparedness and Response Plans as required by the Chief Inspector of Mines’ orders. Through these exercises, the mine managers and responding agencies have a better understanding of their emergency management procedures and requirements.
The Chief Inspector also ordered that companies submit letters:
- Outlining commitments for completing the recommended work proposed in the DSI and third-party review reports, along with a schedule for implementing that work.
- Summarizing their EPRP test and any identified gaps and lessons learned from that test.
The Ministry of Energy, Mines and Petroleum Resources subsequently retained Hatch Ltd. to:
- Assist with reviewing all submissions to ensure consistency and compliance;
- Prepare a summary report; and,
- Establish a platform to release all submissions to the public.
The 2014 DSIs have been completed, with overall observation from the reports suggesting that the dams at the 51 mines reviewed are in good condition, and no immediate safety concerns were identified. Areas of concern were identified by the engineers for specific mines, and recommendations to rectify them were provided to the mine owners.
Copies of the DSIs, as well as permits and amendments and inspection reports for permitted major mines, can be found on the new B.C. Mine Information website.
Letters of Assurance
Additionally, in response to the Mount Polley independent expert review panel recommendations, the Chief Inspector of Mines ordered 38 mines to provide a Letter of Assurance by June 30, 2015 and confirm whether foundation materials similar to those at Mount Polley exist below any of their dams.
Specifically, the mines were ordered to undertake an assessment to determine if any of the dam(s) associated with their tailings storage facilities (TSFs) may be at risk due to:
- Undrained shear failure of silt and clay foundation (e.g. glaciolacustrine deposits – GLU);
- Water balance adequacy; or
- Filter adequacy.
Copies of the Letters of Assurance can also be found on the new B.C. Mine Information website.