Imperial Metals escapes charges from Mount Polley tailings breach

No charges will be laid by the provincial government due to the failure of the Mount Polley tailings dam, said the B.C. chief mines inspector.

"The chief inspector found that the mine and its engineers employed weak practices on the mine site and many recommendations go to new standards and guidelines to improve these practices," said the Ministry of Energy and Mines in a news release.

"Weak practices, however, do not constitute a legal contravention of existing mining legislation.

"The CIM, with advice from the Ministry of Justice, did not find sufficient evidence that Mount Polley Mining Corporation contravened existing regulatory requirements. Based on these findings, the Chief Inspector of Mines determined there were no actions that would warrant a report to Crown Counsel pursuant to the Mines Act."

In August 2014 Imperial Metals' tailings dam at Mount Polley Mine failed resulting in a large debris field and water ban in the British Columbia interior affecting 300 residents.

The mines minister said the regulations around allowable risk are too narrow and new regulations will be forthcoming.

͞"We͛ve learned from this investigation that in the case of Mount Polley, the allowable margin of risk around the design, construction and management of the tailings storage facility was too
narrow to allow for an unknown factor, the layer of unstable soils below the dam embankment.

We've also learned that weak practices on the mine site increased the risk of dam failure and exacerbated environmental consequences from the breach.͟

"This is unacceptable. My commitment is to implement all recommendations, work with the MABC and MAC, the APEGBC and the CDA to ensure that risk of dam failure is reduced by better regulations, better policies and better professional guidelines.͟"

Key recommendations released were the following:

  • All mines with TSFs will be required to have a designated mine dam safety manager and a designated individual to oversee the mine͛s water balance and water management plan.
  • Mines with TSFs will be required to have water management plans designed by a qualified professional.
  • ‡ Independent technical review boards will be required for all mines with TSFs.
  • Establish a dedicated investigation, compliance and enforcement team within the Ministry of Energy and Mines lead by a new deputy chief inspector of mines. This team will provide additional support and oversight of existing ministry investigation, compliance and enforcement functions.
  • To strengthen records management and improve openness and transparency around design, construction and operation, government will establish a formal documentation management system for all TSFs from development to post-closure.
  • Foster innovations in the mining sector that improve current technologies in tailings processing, dewatering and discharge water treatment.