In response to the findings and recommendations of the chief inspector of mines' investigation into the tailings storage facility at Mount Polley Mine in August 2014, the British Columbia government is introducing new regulations and requirements for tailings storage facilities.
“We’ve 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," said Energy and Mines Minister Bill Bennett. "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."
The report found, as did the Independent Expert Panel in January 2015, that the dam failed because the strength and location of a layer of clay underneath the dam was not taken into account in the design or in subsequent dam raises. The chief inspector also found other factors including the slope of the perimeter embankment, inadequate water management, insufficient beaches and a sub-excavation at the outside toe of the dam exacerbated the collapse of the dam and the ensuing environmental damage.
While the breach would not have occurred had it not been for the undetected glaciolaucustrine layer of soils, the consequences of the breach were made worse by the other factors, said the government. Although operations on the mine site were not in contravention of any regulation, the chief inspector found the mine failed to operate using best available practices.
The chief inspector of mines investigation team conducted approximately 100 interviews and reviewed over 100,000 pages of documents going back to 1989. This is the largest and most-complex investigation and analysis ever done in B.C.
The chief inspector made 19 recommendations in seven categories directed toward the mining operator, the mining industry, professional organizations and the government regulator to prevent such incidents in the future and build a safer, more sustainable industry. The government will be working to implement all of the recommendations. Key recommendations include:
•All mines with tailings storage facilities will be required to have a designated mine dam safety manager and a designated individual to oversee the mine’s water balance and water management plan.
•Mines with tailings storage facilities will be required to have water management plans designed by a qualified professional.
•Independent technical review boards will be required for all mines with tailings storage facilities.
•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.
•Strengthen records management and improve openness and transparency around design, construction and operation, government will establish a formal documentation management system for all tailings storage facilities from development to post-closure.
•Foster innovations in the mining sector that improve current technologies in tailings processing, dewatering and discharge water treatment.
Many of these recommendations will be addressed through the review of the
Health, Safety and Reclamation Code for Mines in British Columbia
. The provincial government will also work with industry and professional organizations to implement the other recommendations. It is anticipated this work will be completed by spring 2017.
Other actions will be taken to strengthen government’s compliance and enforcement of mining. Bennett plans to introduce legislation in 2016 to add administrative penalties under the Mines Act. Compliance and enforcement tools under the Mines Act are presently limited to shutting down a mine through the cancellation of a permit, issuance of stop-work orders, or pursuing prosecutions. The proposed legislation would give ministry staff the power to issue penalties for non-compliance.
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. Weak practices, however, do not constitute a legal contravention of existing mining legislation. The chief inspector, 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.
The British Columbia Conservation Officer Service is still conducting its investigation into the Mount Polley accident.
Photo: The results of a tailing pond breach at Imperial Metals Corp's gold and copper mine at Mount Polley in central British Columbia on August 4, 2014. (REUTERS/Cariboo Regional District/Handout via Reuters)
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