A major slope in southern Manitoba is currently experiencing deep seated movements of approximately 60mm per year. This 20m high × 70m long slope contains a pipeline right of way with five large diameter crude oil lines that were constructed from 1950–1998. It is estimated that the slope has moved over 3 meters since the pipeline installations. Management of the effects of this slope movement on the pipelines has involved cross-functional strategies that include geotechnical, integrity, and stress evaluations.
The slope is assessed annually by a geotechnical engineer, and the most likely cause for the slope movements has been determined. Slope monitoring equipment has been installed at key locations and is monitored at frequent intervals. A toe berm has been installed to prevent lower slope failure at the creek bed that is located at the slope toe.
A finite element stress analysis, which considers the interaction between the soil movement and pipeline, has been generated. This stress analysis evaluated the pipeline stresses due to the slope movements to date, and also due to a possible sudden mass movement. The results are backed up by a bending strain analysis based on inertial in-line inspection data was conducted for several of the lines.
This paper presents an overview of the engineering assessment considering structural, material, geotechnical and operational concerns involved in developing an integrity management action plan.