This paper details a case study of an engineering assessment on a pipeline where robust monitoring of continued ground movement and repeat in-line inspection (ILI) supported integrity management decisions and remediation activities.

 

Following a loss of containment incident on a 16-inch diameter pipeline on the south slope of the North Saskatchewan River in July 2016, Husky has undertaken intensive studies to understand and learn from the failure. The cause of the incident was ground movement resulting from a landslide complex on the slope involving two deep-seated compound basal shear slides as well as a near surface translational slide in heavily over consolidated marine clays of the Upper Cretaceous Lea Park Formation. One aspect of the studies has been to undertake structural analysis of the pipeline response to the loading imposed from the ground movement in order to prevent a similar occurrence from happening in the future and determine the integrity of the pipeline at the time of the assessment.

 

Given the scale and complexity of the landslide, slope stabilization measures were not practical to implement, so repeat ILI using caliper and gyro technology, in addition to a robust monitoring program was implemented. Real-time monitoring of ground movements, pipe strain and precipitation levels provided a monitoring and early-detection system combined with documented risk thresholds that identified when to proactively shut-in the pipeline.

 

This paper presents the methodology and findings of the structural analysis that was undertaken to examine the robustness of the pipeline to withstand future landslide movement. The work involved simulation of the pipeline history on the slope including loads that had accumulated in the original pipeline sections based on historical ILI results and slope monitoring. The pipeline orientation was parallel with the ground movement in the landslide complex, so the development of axial strain in the pipeline was the dominant load component which are particularly damaging in the compression zone. The work provided recommendations to ensure the integrity of the pipeline with consideration of continuing ground movement and assisted Husky with decisions over the long-term strategy for pipelines in the south slope of the North Saskatchewan River.

The companion paper presents the findings of the geotechnical monitoring. 


The North Saskatchewan River Valley Landslide \u2013 Slope and Pipeline Condition Monitoring

Division / Sponsors: 
Pipeline Systems Division

Paper Proceedings: https://asmedigitalcollection.asme.org/IPC/IPC2020/volume/84447

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