Entrepreneur Adolph Sutro believed that a tunnel, excavated to intersect with the lower levels of the Comstock, would efficiently drain and ventilate the mines. After a failed early proposal, he incorporated the Sutro Tunnel Company with a legislative charter in 1865. His astonishing plan called for an excavation 20,489 feet or over three miles in length. It would climb one and a half percent from the Carson River Valley near Dayton, intersecting with Virginia City's mines at the 1,640-foot level.