Directional drilling underway for East End Tunnel
LOUISVILLE, Ky. - (April 1, 2011) Directional horizontal drilling is underway in eastern Jefferson County, Ky., where workers are gathering geotechnical data needed for construction of a pair of 2,000-foot-long tunnels, which are part of the Louisville-Southern Indiana Ohio River Bridges Project. This unique and cost-effective method for gathering data will help engineering firms and contractors submit accurate bids when it's time to let the tunnels.
Each drill bit is four inches in diameter and 10-feet long. The head of the bit is controlled by a computer, allowing it to make gentle turns in various directions. The drill rig is set up several hundred feet from the face of the proposed tunnel on the east side of U.S. 42. There will be three borings going under U.S. 42 and the historic Drumanard Estate and extending approximately 2,000 feet to near the exit points of the twin tunnels. The process is expected to take four to six months.
The drill is relatively small – about four-feet tall and 10-feet long – and is submerged in a four-foot pit. It generates little noise, which is desirable because the drilling is near residential areas.
The drilling is taking place in a karst area with the primary rock being limestone, dolomite and shale. Karst means that there is a potential for underground caverns, similar to areas with sinkholes. Less karst and more hard rock, such as limestone and dolomite, will help keep the cost of the tunnel to a minimum.
At nearly a half-mile long, this is considered the longest direction drilling project ever in the U.S. for a roadway project, according to the contractor conducting the work, S&ME Inc. The equipment came from Europe where this type of drilling is more common. It's also used in places like Japan and Hong Kong, where the real estate to conduct this type of project is minimal. In the U.S., directional drilling has been used more in mining and oil exploration than it has road construction.
Left: The drill bit can be seen on the lower left side where it is going into the ground.
Right: Samples taken early in the drilling process have been mostly limestone.
CLICK HERE TO READ STORY: Developers at the Bridges Innovation Forum say the overall project construction time frame could be cut significantly.