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Record Bore Set On Virginia Natural Gas Project
Mears Group, Inc. recently completed a record setting bore as part of the Hampton Roads Crossing being constructed by Virginia Natural Gas (VGN).
The drill consisted of installing 7,357 linear feet of 24-inch steel pipeline under the Elizabeth River. This record setting drill was the second in a series of large directional drills that will be required to construct the pipeline system linking Norfolk to Newport News, VA.
Utilizing complimentary services made available by being part of the Quanta Services network, Mears was able to take on the entire first segment of the project as a turnkey operation, subcontracting sister company Bradford Brothers Inc. (BBI) to handle pipe related activities. BBI not only fabricated the steel pipe for the Elizabeth River bore they also handled the pipe during pullback, performed hydro tests, ran gauging/sizing pigs, and connected the crossing to the first drill installed by Mears on the project; a 1,000-foot installation under the Old Dominion University golf course.
To complete the initial pilot hole under the Elizabeth River, Mears utilized a 660,000 pound drilling rig which was set up in a parking lot on the Old Dominion University campus. In accordance with the design, Mears entered the drill at a 12 degree angle, and ultimately achieved a maximum depth of 110 feet over the length of the crossing. Because local conditions presented many challenges to utilizing traditional land based steering methods, Mears teamed with the general contractor, Weeks Marine Inc., to equip a barge with a mobile coil set-up. This innovative approach allowed Mears to track the drill bit at incremental points along the designed installation route verifying position and accuracy while greatly reducing the impacts of river currents, marine traffic etc., during pilot hole installation activities.
After completing the pilot hole, Mears brought in a second 160,000 pound drilling rig which was set up on the exit side of the crossing and used to assist the 660,000 pound rig with reaming operations. Once the hole had been suitably expanded to 32-inches, the pipeline was connected and pulled back under the Elizabeth River. The pullback process lasted approximately 22 hours from the time the pull head initially entered the hole on the exit side until it reached the entry pit at the rig.