Aerial photograph interpretation is an accurate and economical method of assessing terrain conditions and natural hazards affecting pipelines and other linear facilities. Completed in advance of vehicle and helicopter-based reconnaissance, it provides a comprehensive site overview that cannot be obtained at ground level. Aerial photograph interpretation helps construct and confirm preliminary hazard and stream-crossing inventories, understand hazard mechanisms, and estimate hazard volume and activity. Time series photo interpretation uses several sets of aerial photographs taken of the same area in different years to track changes in terrain, stream patterns and land-use over time. In addition, aerial photographs are superior navigation tools in the field. These points are illustrated using examples from pipelines in British Columbia and Alberta. This work will be of interest to managers of pipelines throughout western Canada, and to those involved with pipeline route selection through mountainous regions.

This paper provides an updated compilation of geohazard-related pipeline failure frequencies for onshore hydrocarbon gathering and transmission pipelines, with a particular emphasis on the analysis of data from Western Europe, Western Canada, the US, and South America. The results will be of interest to owners, operators, regulators and insurers who wish to calibrate estimates of geohazard failure frequency and risk on planned and operating pipelines, particularly for pipelines traversing mountainous terrain. It concludes with an estimate of the global annual frequency of failures caused by geohazards on hydrocarbon gathering and transmission pipelines, and postulates that this failure frequency should continue to decline when measured on a per kilometer basis due to ongoing improvements in geohazard recognition, routing and design of new pipelines, and improvements to integrity management practices for operating pipelines.

In the last 5 years in Canada, regulators have been requesting that new pipeline projects provide quantitative risk management of all credible geohazards involving the proposed pipeline corridor so it can be demonstrated that geohazards are being recognized prioritized and that adequate resources are being allocated and to minimize the impact of adverse consequences of pipeline construction and operation. Complete risk management includes risk analysis that identifies credible geohazards sites, estimates their annual frequency or probability of pipeline failure and, when combined with a consequence of pipeline failure, estimates the risk from each hazard. This paper presents a framework and methodology that quantitatively estimates the Frequency of Loss of Containment (FLoC) for several types of geohazards that meet the requirements for geohazard identification and frequency analysis components of risk analysis. This framework builds on an international geohazard management framework advanced in the last decade by the Australian Geomechanics Society, British Columbia forestry industry, used in geohazard management programs for operating pipelines and proposed pipeline projects in Canada. The framework provides a repeatable and defensible methodology that is intended to be scalable to accept inputs from feasibility level desktop studies, through field-based observations, and incorporate proposed mitigations. This updated framework was most recently implemented on a proposed large diameter transmission pipeline route crossing the varied terrains of Western Canada, the results of which have been adjusted for Owner confidentiality, but are presented to demonstrate the application of the methodology and the effectiveness of communicating the overall hazard frequency reduction as a result of applying site specific mitigations.

Pipeline route selection and design is an iterative process by which one or more potential pipeline corridors are systematically narrowed from the general path of about 10 km in width to a highly specified 30 m to 50 m wide corridor. The process usually spans several years, and is frequently becoming increasingly complicated, requiring a multi-disciplinary technical and managerial approach that considers the political and regulatory process, environmental impact and permitting, project and industry economics, access, constructability, land acquisition, and terrain. Specialist technical contributions to the pipeline routing process include pipeline hydraulics, pipeline and facility construction, terrain/geohazards, and environment/archaeology. Problematic terrain and geohazards are two of several issues that need to be managed through the feasibility and design of a new pipeline project. As the project advances through Front End Engineering and Design (FEED) from feasibility to final engineering design and as the corridor narrows from kilometers to tens of meters in width, the level of detail required in ongoing terrain and geohazard investigations should increase to optimize the design process and match the increased detail being provided by other specialists. An idealized Four-Stage framework for managing geohazards and problematic terrain during pipeline routing and design is outlined in the paper. This framework has been founded on several international resources listed in the references and has, by necessity, been developed, tested, and refined by the authors over the last ten years on several large and small diameter pipeline projects in North and South America. Each of the 4 Stages is described and contains guidelines on project study scale, a target corridor width, the engineering design level, cost accuracy, and geohazard related engineering tasks and deliverables. This staged approach is provided as a road map to help guide all project participants including owners, project managers, engineers, scientists, and regulators to understand how geohazards and problematic terrain are managed through the pipeline routing and design process.

Terrain mapping is the process of the interpretation of aerial photographs, LiDAR and satellite imagery plus field based ground truthing to delineate and characterize terrain polygons with similar surficial materials, landforms and geological processes [1]. For new pipeline projects, detailed terrain mapping is usually completed at a map scale of 1:20,000 corresponding to ground accuracy, at best, of 20 m. Although typically used to support the forestry industry in planning and developing forestry operations in British Columbia, Canada [2], and despite the rapid advancements of remote sensing technology, the art and science of terrain mapping continues to be an essential. albeit somewhat forgotten, tool for new and existing pipeline projects in a variety of terrain settings. For new pipeline projects, a quality terrain mapping product has been be used to characterize ground conditions and support the estimation of design inputs for numerous aspects of pipeline routing and design [3,4]. It is the backbone of most terrain and geohazard related tasks on a pipeline project and it is useful through many stages of a project’s development [5]. At routing and feasibility stages of a project, terrain mapping can be used to efficiently identify geohazards to avoid and to allow comparison of the terrain between different corridor options. Later on at the early design stages, terrain mapping can be used to develop and maintain a geohazard inventory to support geohazard risk assessment and design through geohazards that could not be avoided [6], delineate areas of shallow groundwater where buoyancy control and construction dewatering maybe required, help estimate soil spring parameters to support pipe stress analysis, delineate areas of shallow bedrock to support construction cost estimates and planning [8], and to identify sources of sands and gravels that maybe used for pipeline construction. This paper is intended to re-introduce the ongoing benefits of terrain mapping for new pipeline projects and describe how terrain mapping can cost-effectively support a pipeline project through its lifecycle of feasibility, design, and construction. Examples of the benefits of terrain mapping for routing and design of two proposed transmission pipelines in northern BC are presented. This work will be of interest to project managers, engineers, scientists and regulators involved with routing, design, and construction of new pipelines projects.