Raise Bore Case Study: Application of Raise Bore Installation for Pipeline Construction on Steep Slopes

The construction of the Coastal GasLink (“CGL”) Pipeline encountered a multitude of steep slopes, primarily in the high-altitude sections within the Coastal Mountains near Kitimat, BC. Steep slope pipeline construction offers unique design, safety, and constructability challenges. Varying installation methodologies were utilized by CGL, including the application of a mining technique referred to as a Raise Bore. A Raise Bore is a trenchless installation method consisting of a near-vertical bored section and a horizontal blasted drift tunnel where the pipeline can be installed. This technology has been used extensively in the mining industry and TC Energy utilized this method to install a section of pipe on a previous project in Mexico. The use of a Raise Bore on CGL was the first of its kind for pipeline construction in Canada. This paper discusses the benefits and challenges associated with the implementation of a Raise Bore, as well as the design inputs, execution, risk analysis, and lessons learned from the CGL Project.