Island Copper mine to close in 1996 — Garbage dump proposed

Tucked away in the tranquil fjord country of northern Vancouver Island, the Island Copper mine of BHP Minerals Canada is becoming the focus of some unfamiliar media attention.

This large open pit has kept a low profile over its 2-decade-plus life. But with closure imminent and a proposal to convert the pit into a garbage disposal site being considered, things are changing.

Mining is expected to cease in late 1996. Newly appointed Mine Manager James Excell told The Northern Miner that exploration drilling by BHP continues in the general area and that other nearby copper properties are being reexamined by other companies.

“So far, nothing substantial has presented itself,” he said. On completion, the open pit will be 1.5 miles long, 0.74 miles wide and 1,280 ft. deep. The company has been considering alternatives to the original environmental closure plan. It hopes to find a use for the present mine infrastructure which includes a deep-sea shipping dock, numerous buildings, power plant and — a rarity in this part of the country — 600 acres of flat land.

Following closure, the region will lose an annual $31.6-million payroll and $1 million per year in municipal and regional taxes. If the disposal proposition becomes a reality, the economic impact would be reduced. BHP anticipates other industries will be attracted in due course to the infrastructure and the availability of quality housing. Most of the 560 workforce is housed at Port Hardy, 15 miles away, a scenic town of 5,400. The company is trying to determine how long-term residents feel about the disposal proposition. If response is favorable, BHP will foot the bill for a $1-million feasibility study.

Pre-feasibility studies show that at least 685,000 tons of garbage will be needed annually for the operation to be economic. At that rate, the open pit would serve for more than 500 years.

Vancouver and district produce 2.3 million tons of waste per year and several communities — for example, Victoria, B.C., and Seattle-Tacoma, Wash. — could also become clients.

All locations, including the pit, are on tidewater. Garbage would be separated, compacted and placed in containers at the port of origin. It would then be shipped to Island Copper, unloaded in the pit and periodically covered with waste rock from existing mine dumps. No toxic or special waste would be accepted.

Fifty jobs would be created at the pit and another 80 in transportation. A single ship making a round trip every 36 hours would be needed to meet the minimum delivery rate of 685,000 tons per year.

Once a sufficient thickness of garbage has been accumulated, the upper surface of the dump (more accurately termed a “landfill”) would be sealed, pipes driven into the pile and methane-rich gases drawn off. (Coincidentally, the disagreeable odor emanating from decomposing organic matter would be isolated, as well.)

Richard Robertson, BHP’s manager of engineering, estimates the volume of gas drawn from the landfill would have a heating power equivalent to 10 megawatts (13,400 hp) and could be used for a variety of purposes.

Two suggestions already mooted are the calcining of limestone for agricultural purposes (the rock occurs in the vicinity) and the powering and heating of a tree nursery servicing the forestry industry.

It is planned that leachate, originating from the landfill, would be pumped through a circuit separate from that of the normal pit inflow (mainly rainfall). Leachate is expected to carry a greater variety of contaminants, and consequently, will require more comprehensive purification before being returned to the natural environment.

To March, 1993, total ore and waste taken from the pit since 1971, when mining started, amounted to 1.07 billion tons. Of that amount, 347.6 million tons were ore, grading an average 0.42% copper and 0.017% molybdenum sulphide. The current milling rate is 55,000 tons per day at 0.35% copper. (The molybdenum concentrate carries about 0.1% rhenium and constitutes Canada’s only commercial source of this tungsten-like element.) As the garbage disposal proposal demonstrates, BHP responds quickly to developments in the industry. An in-pit crusher and 2,500-ft. conveyor tunnel were introduced into the mining plan in 1984. Crushed ore is delivered directly to the mill, saving a considerable expense in truck haulage. This innovation, together with the construction of a unique concrete wall (4,000 ft. long and 80 ft. deep) gave the mine an extra five years of productive life. The concrete wall, seated in indurated and impervious till, allowed the pit wall to be pushed back into an area previously held by the sea.