Pilot Bore Pays Off

by R.W. Humphries, (M.ASCE), Principal of Golder Associates, Inc.; Atlanta, Georgia,

Serial Information: Civil Engineering—ASCE, 1990, Vol. 60, Issue 1, Pg. 60-62

Document Type: Feature article


The primary purpose of tunneling through Cumberland Mountain is to ease the 18,000 vehicle per day traffic through the rugged terrain that was a major transportation route when Daniel Boone led settlers into Kentucky's Bluegrass region. The bonus is that the National Park Service will be able to restore the Cumberland Gap National Park to the trail condition that those settlers traversed. The pilot, which will serve as the crown drift in the final southbound tunnel, was excavated in 1986 by drill and blast methods, with muck handled by rail equipment. The pilot is about 4,000 feet long and nominally 10 by 10 feet. The purpose of the pilot tunnel was to obtain information that would lead to lower costs than might otherwise have been bid for the twin tunnels. slightly concerned when seeping oil showed up in the Newhall Tunnel, the last leg of a project that brings water to a treatment plant near Los Angeles. The oil in the water made normal treatment operations impossible. Various sealing and plugging attempts were made, but none were successful. The solution was a 3,000 ft liner that had to be slipped inside the dewatered tunnel by sections. The job was made even more challenging by the varying diameter of the tunnel.

Subject Headings: Water treatment plants | Tunneling | Mountains | Vehicles | Traffic management | Terrain | Routing (transportation) | Federal government | Los Angeles | California | United States

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