ODDS’N’SODS — Survey control underground essential to

Survey control in underground mines is essential to ensuring the efficiency of mining systems.

I vividly recall my first venture into a mine, in the early years of the Second World War, at the Red Rose tungsten operation, south of Hazelton, B.C. Jack Zucco, the mine foreman, devoted every Saturday to surveys. I was selected as Zucco’s helper and armed with transit, chains, plumb-bobs, level and level rod. We endeavored to detail all the week’s work and to lay out controls for ensuing programs; we surveyed advances made in the drifts and raises; we mapped the progress in the stopes; and we set control “spads” in place in new entries to provide guidance.

Jack was a stickler for elevation control, so we conducted “level” surveys on newly laid track in all headings. Much use was made of red paint to mark “tights” on the walls of drifts where dimensions were too limited, and to mark, as well, survey control holes to be drilled. Jack ran a “tight ship” with his transit.

In later years, I was involved in transferring control surveys from the surface to underground levels. At the Pioneer gold mine in British Columbia, Hughie Langille was fond of the “2-wire system,” which involved suspending two fine, steel wires in the shaft and setting the large plumb-bobs at the bottom in oil containers in order to dampen the oscillations of the wires. The co-ordinates and azimuth of the two wires were first determined by a transit survey on surface. The transit was then set up in the shaft station on each level in the mine; and then, by moving the telescope until it was on a straight line with the two wires, the azimuth and co-ordinates of the wires were transposed to two or three points (or stations) on each level. Elevations were transferred more directly by simply measuring the distances down the shaft with a steel chain.

To compensate for any possible error in this procedure, Langille would insist on a survey through the first raise driven to connect two levels. In general, though, the system was reliable, provided the transit and tape were used very carefully. Accuracies in the order of 1-to-5,000 were achieved. Much more involved was the survey work at the Quirke mine shafts, where the 3-wire Weisbach system was

preferred. The routine there required two or more crews, each of which was equipped with transits and tapes.

After establishing the co-ordinates of each wire on surface, surveying was performed on each level station. Each wire turned 5 or 6 angles from a transit set up in each station and measured the distances between each wire. This was delicate and deliberate work, and was made doubly difficult by the fact that we were moving about in an open shaft.

Fortunately, the calculations were standardized so that once the work was completed in the station, results could be confirmed; then, and only then, could the survey crew move to the next shaft station. This was an extremely precise system — so much so that accuracies in the order of 1-to-10,000 were required.

At the Granduc mine, in establishing controls for the 10.3 miles of tunnel, Nick Gritzuk was much more of a stickler. Nick wanted accuracies in the order of 1:50,000, as well as “laser beam” controls on the face of the advancing tunnel.

Thus, the contracting engineering firms conducted six separate theodolite surveys between the Tide Lake portal and the mine at the Leduc end — over mountains and glaciers. However, excellent results were achieved as the tunnel broke through, right on the mark, and the elevations were a mere 1.3 ft. low.

In hindsight — oh, the tedium of working with transit, plumb-bob and chain; what with wind blowing the “bob” cord, the ore haulage crew waiting to pass, water splashing down one’s neck, and the shift boss cursing and glowering at the delays — it is a wonder that we managed to carry out the work with such accuracy.

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