Statement by engineering firm Knight Piésold Ltd. regarding the Mount Polley mining incident

— Photo courtesy Imperial Metals

The breach of the tailings storage facility at Mount Polley is an extremely unfortunate incident and Knight Piésold Ltd. shares the concerns with respect to the effects to local communities, First Nations and the environment.

Going forward there will be a comprehensive examination of this incident and there will be questions about the engineering and design of the tailings storage facility. As the former Engineer of Record of the tailings storage facility at Mount Polley, we feel it appropriate to provide some clarity and transparency of the role of Knight Piésold Ltd.

Knight Piésold Ltd. informed Imperial Metals that we would not continue as the Engineer of Record for the Mount Polley Mine on February 10, 2011, and subsequently ceased to perform that role. During the time we acted as Engineer of Record, the tailings storage facility at Mount Polley operated safely and as it was designed. A third party Review Panel provided independent review of the tailings impoundment design during initial construction and permitting during 1995 to 1997. In 2006, while we were Engineer of Record, an Independent Third Party Dam Safety Review by AMEC Earth and Environmental confirmed that the three embankments were well-designed and well-constructed entities from a dam safety perspective.

Since February 10, 2011, Knight Piésold Ltd. has not had any responsibility or knowledge of any aspects of the design, modifications or performance monitoring of the tailings storage facility at Mount Polley. The original engineering done by Knight Piésold Ltd. accommodated a significantly lower water volume than the tailings storage facility reportedly held at the time of the breach. Significant engineering and design changes were made subsequent to our involvement, such that the tailings storage facility can no longer be considered a Knight Piésold Ltd. design.

Upon completing all assignments as the Engineer of Record in 2010, Knight Piésold Ltd. wrote to Mount Polley Mining Corporation and to the Government of British Columbia's Chief Inspector of Mines and stated that "the embankments and the overall tailings impoundment are getting large and it is extremely important that they be monitored, constructed and operated properly to prevent problems in the future." (See attached letter dated February 10, 2011). A formal handover of design, construction and monitoring responsibilities was conducted on March 8, 2011 when AMEC Earth and Environmental was acknowledged as the new Engineer of Record for all future work at the Mount Polley tailings storage facility.

Knight Piésold Ltd. is not familiar with, and therefore cannot comment on, the details of the incident, or on the design, construction, operations, water management practices or any other aspects of the Mount Polley tailings storage facility.

Knight Piésold is an international consulting group providing engineering and environmental services for the mining, power, water, transportation and construction sectors. With offices around the globe, our team of over 800 experienced professionals delivers high quality specialized services and innovative solutions that respect social, environmental and economic responsibilities.

SOURCE: Knight Piésold Ltd