On the Job: HDD Technology's U.S. Debut
January 3, 2011
In order to comply with Florida’s increasing demands for energy while ensuring reliable supplies of natural gas, the Florida Gas Transmission Co. currently is expanding its pipeline network. The “Phase VIII Expansion” project adds 480 miles of pipeline to the network, allowing it to convey more gas from Houston across the Gulf of Mexico to Florida. This additional natural gas primarily is used for electricity generation in local power plants, thereby covering the daily power requirements of up to 1 million households.
The main contractor, Sheehan Pipe Line Construction Co., Tulsa, Okla., commissioned REM Directional Inc., Boligee, Ala., with implementing the requisite crossings for the pipeline installation. So far, horizontal directional drilling or auger drilling technologies have been used, based on the respective project requirements. For the crossing under Highway 70 in Arcadia, Fla., the new Herrenknecht Direct Pipe method was used for the first time in the United States. The construction company preferred this solution as the geological layers containing ground water, shells, sand and clay can be safely crossed – in some cases at a depth of only 7 feet – allowing for an accurate alignment with a horizontal and vertical curve.
During the installation process, slurry tunneling with the Herrenknecht Direct Pipe machine guaranteed the requisite precise pressure control of the tunnel face, preventing settlements or heave on the site surface. The Herrenknecht’s navigation system with gyro-compass and electronic hydro level keeps the machine on the specified three-dimensional curve with vertical and horizontal curve radii of 3,000 feet and 6,000 feet, respectively, for a safe and exact course. The pipe thruster is anchored in the launch pit, and thrusts the prefabri cated pipe string that has been laid in advance. The average thrust force of 15 tonnes is transferred to the Direct Pipe machine ahead. Highway 70 was swiftly and safely underpassed using this award-winning (Iploca Award in 2009) method. Despite the three-dimensional curve, only three drilling days (single-shift operation of 12 hours) were required for exact and safe installation of the 705-foot pipe string.
REM Directional Inc. is one of the largest directional drilling companies in the Southeast. Its projects have covered utility, gas pipeline, and communications markets, ranging from 4 inches to 48 inches.