Odds ‘n’ Sods — Water, water, everywhere

We had just arrived back at our homes after a busy day at the Quirke mine in Elliot Lake, Ont., when an emergency call informed us that the mine was flooding.

It was 1956 and the mine was serviced by a single shaft which accommodated cages, skips, a service compartment and manway. Production had just started, following an extensive development program, and the mine operation was continuous on three shifts so that a full crew was always present. Barry Bourne, the mine superintendent, phoned to advise me that the shaft pumps were holding the water level in the shaft sump and the crew had been hoisted to surface. The immediate and pressing challenge was to locate and attempt to control the inflow. We would meet forthwith with the mine captains and mine engineers at the headframe.

Following a hasty conference, we decided to order more pumps from mines in the area, to support the existing units, and then send a team underground to check the mine, level by level, for water flows. We soon learned that flows had nearly sealed off the fifth level with broken ore material. However, the situation at the other six levels was found to be normal. There followed a detailed inspection of the fifth level, which revealed that one stope opening, recently blasted, had received a monstrous inflow of water through a hole in the back of the stope. We immediately scanned the stope plans and the surface drilling maps to locate the diamond drill hole that was the source of the inflows.

During the period of the exploration, several holes had been drilled from Quirke Lake off the ice and, as well, beside the creek draining the adjacent valley. These holes had been cemented and grouted to prevent water from entering the underground mine. For additional protection and safety, ore pillars had been left in the areas where holes were to be drilled near mine openings.

We soon located the miscreant hole and found that, indeed, we were draining an arm of the creek where one hole had been collared but not adequately cemented. Fortunately, we had an able shaft captain in Danny Smith and two very capable shaft men in Stan Denoski and Phil Edwards, all of whom had substantial experience coping with water inflows. The team set to work drilling additional holes from the back of the stope around the main drill hole. Their objective was to intersect the surface hole and so tap off the water flow through these auxiliary openings, and thus permit a plug to be inserted in the main drill hole. Meanwhile, further pumps were set up in the main shaft sump to contain the flood of water.

By dent of hard work and courageous persistence, the team was able to seal off the errant drill hole and begin to pump cement and grout into the opening from a well-directed drill hole from the stope. This was deemed to be satisfactory by the provincial mines ministry, so that partial production could be resumed after a few days.

In consequence of this event, we reviewed all the surface drill holes in detail, as well as the cementing records for each hole. A further study was made of the local mine pillars planned around each area of a projection of a surface hole.

Later, when we were mining well under Quirke Lake, we faithfully test-drilled ahead of all development openings and made doubly sure that all surface-drilled holes were carefully screened for cementing. To be extra prudent, we made sure that additional pumping capacity was installed in the second shaft opening and the escape route system.

Nevertheless, the flooding of underground mines remains an ever-present threat, so that even the best advice and actions must be buffered with an ever-constant vigilance.

— S.J. Hunter, a retired mining engineer and regular contributor, resides in Vancouver, B.C.