Drilling with Direction

by W. Douglas Ensor, (F.ASCE), Vice Pres.; Gannett Fleming, Newport News, VA,
Everett P. Skipper, Proj. Mgr.; Gannett Fleming, Newport News, VA,
Peter S. Fortin, Engrg. Mgr.; City of Norfolk, VA,

Serial Information: Civil Engineering—ASCE, 1993, Vol. 63, Issue 9, Pg. 48-51

Document Type: Feature article


Norfolk, Va.'s 48 in. diameter raw water main crosses three rivers in its 52,000 ft route. At the Elizabeth River, an aerial or subaqueous crossing was not feasible, so a technique known as horizontal directional drilling (HDD) was selected. At 2,160 ft, the HDD project is the longest (with 48 in. diameter pipe) ever completed in the world. The HDD project avoided wetland areas, a contaminated river bed and the need to deepen the river channel, creating an estimated savings of $4 million. Pipe was delivered to the site by railroad in 80 ft steel sections weighing 15 tons each. A single pipeline was welded from 27 sections on a marshy, narrow, curving site west of the river. Using gravitometric and magnetic tracking systems, the contractor completed the 8 in. diameter pilot hole in two days. After reaming the hole to 60 in. diameter, the contractor connected the drilling stem to the pipeline and pulled it back under the river in just 30 hours, including a 12 hour period during which the pipe jammed in the hole. It resisted the 500,000 pound pull of the drill rig and the push of two tractors until the contractor carefully created partial buoyancy in the lead section of pipe to loosen it and complete the record setting, $4.2 million project.

Subject Headings: Drilling | Project management | Pipe sizes | High-rise buildings | Contracts and subcontracts | Steel pipes | River and stream beds

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