Pipeline Geo-Environmental Design and Geohazard Management
3 Open Cut and Elevated Pipeline River Crossings
Historically, the frequency of pipeline exposures and failures at river crossings has exceeded that of overland pipelines. Major constructed and proposed projects, especially those in extreme environments in the Arctic or the rugged terrain of the Andes in South America, have evolved the science of river crossing design. Extensive regulatory reviews of major projects have also influenced the design process significantly. Government mandated operational monitoring requirements and the owners Best Management Practices re: maintenance has, in combination with the more rigid design process and improved quality control during construction, reduced integrity concerns associated with river crossings.
An increasing challenge in the last several decades is the environmental restrictions associated with instream construction. This has lead to significant improvements in the development of trenchless crossing techniques such as horizontal directional drilling (HDD). Nevertheless for economic or technical reasons, open cut crossings, with or without flow isolation during construction, will remain a dominant river crossing construction method. To a smaller degree, except for unique cases such as a hot-oil pipeline in the Arctic, elevated river crossings, ranging from simple pipe spans to long suspension bridges, are alternative methods of construction.