TORONTO (miningweekly.com) – In response to the August 2014 findings and recommendations of the chief inspector of mines’ (CIM’s) investigation into the tailings storage facility (TSF) at Mount Polley mine, Energy and Mines Minister Bill Bennett announced last month that the British Columbia government would introduce new regulations and requirements to improve safety standards for tailings storage facilities.

The CIM 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.

“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.

“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,” stated Bennett.

The CIM also found that 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 dam collapse 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 compounded by the other factors. Although operations on the mine site were not in contravention of any regulation, the chief inspector found that the mine failed to operate using best available practices.

The CIM investigation team conducted about 100 interviews and reviewed more than 100 000 pages of documents going back to 1989. This was the largest and most- complex investigation and analysis ever done in British Columbia.

The team made 19 recommendations in seven categories directed at the mining operator, the mining industry, professional organisations and the government regulator to prevent such incidents in the future and to build a safer, more sustainable industry.

Government stated that it would be working to implement all of the recommendations.

Key recommendations were that:

• All mines with TSFs would be required to have a designated mine dam safety manager and a designated individual to oversee each mine's water balance and water management plan;

• Mines with TSFs would be required to have water management plans designed by a qualified professional;

• Independent technical review boards would be required for all mines with TSFs;

• A dedicated investigation, compliance and enforcement team within the Ministry of Energy and Mines lead by a new deputy chief inspector of mines would be established. This team would provide additional support and oversight of existing ministry investigations, as well as compliance and enforcement functions.

• Records management should be improved, together with openness and transparency around mine design, construction and operation. Government would establish a formal documentation management system for all TSFs from development to post-closure.

• Innovations in the mining sector that improve current technologies in tailings processing, dewatering and discharge water treatment should be fostered.

Many of these recommendations would be addressed through the review of the Health, Safety and Reclamation Code for Mines in British Columbia. Government would also work with industry and professional organisations to implement the other recommendations. This work is expected to be completed by spring 2017.

Other actions would be taken to strengthen government’s enforcement of compliance with mining standards. Bennett planned to introduce legislation in 2016 to add administrative penalties under the Mines Act.

Compliance and enforcement tools under the Mines Act are currently limited to shutting down a mine through the cancellation of a permit, issuing stop-work orders, and pursuing prosecutions. The proposed legislation would also give ministry staff the power to issue penalties for noncompliance.

The CIM also found that the mine and its engineers employed weak practices on the mine site and many recommendations seek new standards and guidelines to improve these practices. Weak practices, however, did 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 contravened existing regulatory requirements. Based on these findings, the CIM determined that there were no actions that would warrant a report to Crown Counsel pursuant to the Mines Act.

The British Columbia Conservation Officer Service (COS) was still conducting its investigation into the Mount Polley accident.

The COS investigation was based on compliance with the Ministry of Environment legislation. It is possible that this investigation might find noncompliance that would warrant a report to Crown Counsel.