FACTS & FIGURES — Significant drilling exploits

Long recognized as the Canadian West Coast’s worst underwater shipping menace, the twin peaks of Ripple Rock in Seymour Narrows lie just nine feet below the water’s surface at low tide. The “Rock,” about 100 miles north of Vancouver in the “inside passage” to Alaska, has defied numerous attempts to demolish it.

In 1953, Boyles Bros. Drilling was awarded a contract to probe the underwater rock structure to determine whether it could be removed by undersea explosion. The plan called for the sinking of a 500-ft. shaft on Maude Island; from this shaft, Boyles would drill a directional test hole which would curve half a mile to Ripple Rock.

Two shafts would then be thrust up into the rock, one into each of the rock’s pinnacles, and the upper strata of the rock examined to determine the best method of planting explosive.

Boyles completed the 6-month project early in 1954. In 1958, nearly 1,400 tons of an explosive were used to blast the rock into non-existence. It was considered the world’s largest non-atomic, non-military explosion. ————————————

In 1981, Hosking Diamond Drilling claimed an industry world record for a hole drilled near Rouyn-Noranda, Que. The hole was drilled jointly for Noranda Exploration, Falconbridge Copper (Lac Dufault), and Soquem. It went down 6,009 ft. and was drilled AQ size from top to bottom. At final depth, the hole was fewer than two degrees off vertical, without any use of wedges. ————————————

In 1930, Longyear was awarded the contract for preliminary test borings for the piers and anchorage site of the Golden Gate Bridge which would link San Francisco and Marin Cty. in California.

Sixteen holes, ranging in depth from 15 to 141 ft., were drilled in 90 days and Longyear was paid close to $15,000 for the work. The bridge, with a centre span of some 4,200 ft., was finished in May, 1937, at a cost of $35.5 million.

Longyear returned to the site in 1991 to carry out seismic investigation drilling as a means of testing the stability of the bridge. An 11-hole drilling program tested and corrected the more vulnerable approaches to the main span. One test pulled 165,000 lb. per sq. inch without the rock failing. n n

In March, 1973, Heath & Sherwood Drilling of Kirkland Lake, Ont., began a 3-month project at the Polaris mine site in the Northwest Territories — a project that would be known as the most northerly underground drilling program in the Western Hemisphere.

Situated on Little Cornwallis Island and jointly held by Cominco and Bankeno Mines through Arvik Mines, the site lies 1,750 miles due north of Winnipeg, 2,200 miles northwest of Toronto and 600 miles north of the Arctic Circle. Development took place entirely in permafrost and 12-hour drilling shifts were broken up by a trip to surface for a warm lunch to offset the 20F working temperature of the mine.

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In 1961, Heath and Sherwood provided technical assistance in the form of equipment and supervisory personnel for a depth-testing project at Latin America Mines’ Quetena property. It was theorized that, below an extensive area of leached breccia, there should be a region of copper values of secondary enrichment.

The leached material to be penetrated consisted largely of a semi-porous mass containing considerable clay, iron sulphates and sericitic kaolinite — all friable and unstable ground which expands on contact with water. In drilling through it, the sides of the hole tend to slough in and seize the string of rods, making it impossible to use water for drilling.

Compressed air was the medium used for removing cuttings from the hole, using tricone bits tipped with tungsten carbide. After the hole was drilled through to stable rock, conventional drilling methods were used. It is interesting to note that the shipment of material from Kirkland Lake to Antofagasta, Chile, consisted of some 70 tons in 59 crates.

— From a Canadian Diamond Drilling Association publication.