Comstock Lode - The Sutro Tunnel

The Sutro Tunnel

While there was a scarcity of water on the surface, there was an excess of water underground in all the mines. Floods in the mines were sudden and miners narrowly escaped being drowned by vast underground reservoirs that were unexpectedly tapped. Intrusion of scalding-hot water into the mines was a large problem, and the expense of water removal increased as depths increased. To overcome these troubles, Adolph Sutro conceived the idea of running a drain tunnel under the Comstock Lode from the lowest possible point. A survey was made by Schussler and work commenced in October 1869. The Sutro Tunnel was completed from the valley near Dayton through nearly four miles of solid rock to meet the Comstock mines approximately 1,650 ft (500 m) beneath the surface. From the main tunnel, branches were run north and south along the vein a distance of over two miles (3 km), connecting to various mines. The tunnel was 16 ft (4.9 m) wide and 12 ft (3.7 m) high. Drain flumes were sunk in the floor and over these were two tracks for horse carts. It required over eight years to complete construction. The tunnel provided drainage and ventilation for the mines as well as gravity-assisted ore removal. However, by the time the tunnel reached the Comstock area mines, most of the ore above 1,650 ft (500 m) had already been removed and the lower workings were 1,500 ft (460 m) deeper still. Although virtually no ore was removed through the tunnel, the drainage it provided greatly decreased the operating costs of the mines served. The ventilation problems were solved at about the same time by the use of pneumatic drills.