Clarification (October 24, 1988)

The Denison-Potacan Potash Company, a partnership of Denison Mines (TSE) and Potash Company of Canada, has been as thorough in its implementation of rock mechanics engineering at its Sussex, N.B., potash mine as any mining company in Canada.

Although all of the circumstances surrounding two deaths at the mine (N.M., Oct 17 /88) as the result of a rock fall have not been determined, The Northern Miner would like to make clear that the partnership has indeed used rock mechanics research in all facets of mine planning, development and operation. The joint health and safety committee at the mine concluded that “the accident could not have been foreseen.”

According to David Waugh, superintendent of engineering for the project, the project has spent more than $1.3 million on its rock mechanics program to date and continues to spend money on rock mechanics with $300,000 budgeted for 1989. Those expenditures include ongoing underground instrumentation, microseismic monitoring and computer modelling.

“It is unlikely that any other potash mine has ever began production with as much prior work and understanding of their rock mechanics behaviour,” says Waugh.

“We had the benefit of the experience of other potash mines in Saskatchewan and Europe, including our partner’s in Germany and France, as well as our own very progressive program.

“The mine was designed with full rock mechanics consideration and continues on a day-to-day basis with the rock mechanics department approval required on all mine layouts.”

Shaft sinking began at the mine in September, 1979, and by November a rock mechanics consultant had been engaged by the project, later augmented by a second consultant.

Lab testing using surface drill cores began in 1979. In 1982, the geological engineering department of the University of Waterloo began extensive testing of underground core samples establishing a direct relationship with the project which has continued over the past six years.

As part of the rock mechanics program, a site was instrumented during the pre-feasibility exploration program in August, 1982. The feasibility study, prepared for the project in the fall of 1982, included extensive discussions of the rock mechanics behaviour of the deposit and from that understanding the development of a mine design and excavation strategy developed.