Rescued Chilean miners can thank Errol MacBoyle
Special to The Union
n 1935-36, Errol MacBoyle, principal owner of Grass Valley’s big-producing Idaho-Maryland gold mine, authorized an interesting experiment in mining technology at a location on mine property near Brunswick Road.
He directed his engineer, J.B. Newsome, to bore an experimental vertical shaft 5 feet in diameter some 1,125 feet into the earth through solid rock to gain access to the horizontal mine tunnels below.
Sound familiar? It is the same process used to free the trapped Chilean gold and copper miners who were rescued this week by way of a vertical shaft, which had been sunk 2,300 feet into the rock. All 33 miners were brought to the surface after having been imprisoned underground for more than two months.
Back to our pioneering project. The traditional method to sink vertical or incline shafts called for drilling, blasting and then “mucking out.” Mucking is shoveling the loose dirt and rock, usually by hand into carts, and then it is hauled to the surface for disposal.
Timbering followed to provide support for pipes, power cables and other necessary equipment. This process was expensive and required constant and costly maintenance.
Newsome’s vertical bore required no maintenance, and the necessary cables could be bolted to the shaft walls. Steel cage guides for transporting the miners to and from the work level were easier to attach to the smooth shaft surface than to an uneven one caused by blasting.
The experimental shaft passed near the 500, 750 and 1,100-foot levels of the original Idaho-Maryland workings. The resulting shaft cores are on display around western Nevada County; it would be interesting to know at what vertical level each core was taken.
Newsome designed and built special equipment for the experiment. A rotating, vertical core barrel drill and a core puller both drilled and removed sections of rock, which were usually 7 feet in length and weighed about 11 tons each.
According to MacBoyle, the greatest footage drilled during a three-day period was 21 feet through solid rock.
Bob Wyckoff is a retired Nevada County newspaper editor, publisher and an author of local history. Contact him at firstname.lastname@example.org or P.O. Box 216, Nevada City, CA 95959.
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