Deer Mountain is an active landslide complex near Swan Hills, AB. Pembina owns two pipelines that traverse the landslide. Prior to abandonment, four leaks occurred on the NPS 8 pipeline due to interaction of circumferential stress corrosion cracking and ground movement. The NPS 10 pipeline is operating and has not leaked, but has previously been strain relieved in several locations.
To develop and execute a geohazard management plan for the operating pipeline, Pembina integrated pipe and ground monitoring data with historical information into a geographic information system. Locations of bending strain areas, strain gauges, pipe wall assessment (PWA) anomalies, slope inclinometers, and piezometers were cross-referenced with previous leak sites, historical dig sites, historical strain reliefs, and areas of shallow pipe burial.
Overlaying the PWA with pre-existing pipe data allowed for identification of segments with a higher density/magnitude of suspected soil to pipe interactions. Strain monitoring, strain relief, and a surface pipeline segment were prescribed. A detailed monitoring plan was also produced for the landslide complex.
This case study presents the process of integrating data, specifying monitoring/mitigative measures, and implementing strain relief at four locations. Additionally, the paper will discuss the design of the surface pipeline segment.