VANCOUVER, BRITISH COLUMBIA--(Marketwired - Jan 30, 2015) - Imperial Metals Corporation (III.TO)

The Mount Polley Independent Expert Engineering Investigation and Review Panel (the "Panel") released today its report (the "Report") on the cause of the August 4, 2014 tailings storage facility ("TSF") breach at the Mount Polley mine.

The Panel's determination of the cause of the breach is in agreement with the results of the investigation of mine operator Mount Polley Mining Corporation ("MPMC"). The Panel found no evidence of failure due to human intervention, overtopping, or piping and/or cracking resulting in internal erosion. The Panel indicated that the water accumulation within the TSF was not a cause of failure but contributed to the release of tailings. The Company had earlier recognized that water levels would increase in the TSF, and had taken steps commencing in 2006 to address this issue.

The Panel concluded that the Perimeter Embankment of the TSF failed because a glacio-lacustrine layer (the "GLU") lying approximately 8 metres below the base of the dam in the area of the breach was not as strong as had been assumed in the design of the TSF.

Construction over the 18 year life of the TSF was at all times carried out in accordance with design criteria provided by the Engineers of Record and approved by the Ministry of Energy and Mines ("MEM"). The Panel noted that the omissions associated with site characterizations remained undetected notwithstanding the large number of experienced geotechnical engineers associated with the TSF over the years.

Design criteria accepted for the TSF required a factor of safety of 1.3 during the operating life of the mine, increasing to 1.5 at closure. Based on the calculations presented in the design reports, the factor of safety of the Perimeter Embankment where the failure occurred exceeded 1.5 at the time of failure.