Introduction
Installing a pipeline crossing beneath a sensitive resource over a length exceeding 15,000 feet may seem like a dismaying endeavor for the majority of companies. Even in ideal conditions, drilling over 15,000 feet of any diameter hole would be a formidable challenge for even the most experienced HDD driller. This challenging scenario came to realization as WBI Energy, Inc., a subsidiary of MDU Resources Group, Inc. (NYSE:MDU) (WBI) was selecting the route for a proposed 24-inch natural gas line that involved approximately 60 miles of new NPS 24 (24-inch O.D.) steel pipeline that would connect WBI’s Tioga Compressor Station near Tioga, North Dakota, with Northern Border Pipeline Company’s mainline at a new interconnection point south of Watford City, North Dakota. The pipeline is for natural gas takeaway to help reduce natural gas flaring in the area.
The selected route would require WBI to cross Lake Sakakawea adjacent to Tobacco Gardens Resort, near Watford City, North Dakota, and comply with requirements of the Garrison District of the United States Army Corps of Engineers (USACE) for horizontal directional drilling (HDD).
With HDD as the only practical method of installing a crossing of such substantial length, WBI enlisted the services of CCI & Associates Inc. (CCI) to develop a design that could be used to successfully traverse the lake. After reviewing the existing conditions, recently completed crossings and available details of the area, a preliminary HDD crossing design exceeding 15,000 feet in length was developed as a basis for subsequent site characterization efforts.
Author
B. Kerby Primm, P.E., CCI & Associates Inc.
