British Columbia (BC) energy and mines minister Bill Bennett has said that the provincial government will not charge Imperial Metals for the Mount Polley tailings dam failure.
The breach occurred at the Mount Polley copper and gold mine tailings pond on 4 August 2014 in the Cariboo region of central British Columbia.
The dam failure released its water and slurry with mining waste into Polley Lake and continued into nearby Quesnel Lake and Cariboo Creek.
In response to the findings and recommendations of the chief inspector of mines' (CIM) investigation into the tailings storage facility (TSF) at the mine, Bennett said that the government will introduce new regulations and guidelines.
The CIM report found that the dam failure occurred as the strength, as well as location of a layer of clay underneath the dam was not considered during the design or in subsequent raising of height of the dam.
Chief inspector of mines Al Hoffman said: "We conducted a very thorough and in-depth examination of the Mount Polley Mining Corporation's actions from its initial site investigations 26 years ago to present.
"Through our investigation, we determined that while the mine did not contravene any existing regulatory requirements, its management and operational practices failed in a number of areas such as water management and misplaced confidence in the TSF design."
Hoffman made 19 recommendations in seven categories directed toward the mining industry to avoid another dam collapses.
The recommendations require all mines with TSFs to have a designated mine dam safety manager and an individual to oversee the mine's water balance and water management plan.
These mines should also have water management plans designed by a qualified professional and engage independent technical review boards.
In the investigation, Hoffman found that the mine and its engineers employed weak practices on the mine site.
Image: Mount Polley Mine site in British Columbia on July 24 2014 prior to the dam breach on August 4 2014. Photo: courtesy of Jesse Allen.