Pembina Pipeline Corporation (Pembina) monitored three active interacting [1] landslides utilizing arrays of remote real-time GNSS (Global Navigation Satellite System) sensors to assist in the confirmation of safe continued pipeline operation. Each case study utilized remote sending high-precision real-time GNSS sensors to monitor landslides of varying movement rates, from slow-moving landslides which could be condition-monitored for many years, to fast-moving landslides which required pipeline mitigation within months. The first case study was Henderson Creek near Grande Prairie AB, which utilized remote real-time GNSS sensors to monitor over one meter of rotational slope movement in 6 months; both a conventionally-buried pipeline, and a temporary above-ground pipeline bridge were monitored before a permanent HDD replacement mitigation was completed. Sensors were installed on the temporary pipeline, the bridge, as well as shallow ground installations. The second case study was Athabasca River north slope near Ft McMurray AB, which utilized remote real-time GNSS sensors to monitor an above-ground pipeline in a slow-moving valley-scale landslide over a period of several years. The third case study was Smoky River east slope near Grande Cache AB, which utilized remote real-time GNSS sensors to monitor a rapidly-moving landslide on a conventionally-buried pipeline, which has plans for an HDD replacement mitigation in the near future. To verify the results of the GNSS sensors, each of these three landslide sites were monitored utilizing multiple technologies which showed close correlation with the remote real-time GNSS sensors, including conventional ground surveys, monitoring pin surveys, SIs, and repeated ILI IMU caliper runs. The GNSS monitoring system was precise enough to detect operational changes of the above-ground pipelines, including filling of the pipeline with product, suspected changes in internal pipeline operating pressure, and pipeline expansion and contraction due to temperature changes from night to day and winter to summer. Pembina successfully utilized a remote real-time GNSS monitoring system to allow greater assurance of safe continued pipeline operation at three separate moving slopes, until either a slope movement threshold was reached, or mitigation was completed. This paper highlights that pipeline operators can remotely condition-monitor their confirmed or suspected interacting pipelines in landslides with accuracy using remote real-time GNSS, on a real-time continuous basis as part of their Geohazard Management Program.

Flood monitoring is one method currently being used by the pipeline industry to provide alerts when flooding is approaching, or has exceeded, levels that could create hydrotechnical conditions that threaten pipeline integrity. Flood monitoring does not provide protection from hydrotechnical hazards or reduce the probability of failure, but can lower risk by providing advanced warning, allowing operators to initiate actions that reduce the consequences of failure in the rare event that pipeline integrity is threatened by hydrotechnical forces. Pipeline pressure reduction, shut-in, purge, and spill response mobilization are all examples of actions commonly used to reduce failure consequence. However, these actions require time to execute, ranging from a number of hours to a number of days, depending on factors such as site location, valve spacing, and product type. The effectiveness of flood monitoring as a consequence reduction strategy is contingent on having sufficient time to implement the flood response action. In designing a flood monitoring program, it is necessary to ask: can flood monitoring provide sufficient advanced warning for an action plan to be fully executed before pipeline integrity is compromised? The present study evaluated 35 high priority pipeline watercourse crossings, to estimate the flood return periods at which actions could be taken that correspond to warning times of 12, 24, 48, and 72 hours before the critical flood (i.e., a conservative estimate of the flow at which fatigue failure is considered possible) and to evaluate the feasibility of flood monitoring as a short-term risk management strategy prior to mitigation. The 35 crossings are currently scheduled for mitigation and rely on flood monitoring as an interim risk management tool. The rate of increase in flood discharge during all previously recorded flood events at each real-time monitoring gauge was first obtained to estimate the rate of flow increase during the critical flood event. Of the 35 crossings, 33 had a maximum warning time of less than 48 hours. Using a 24-hour warning time, 10 of the 35 crossings have a warning flow of less than a 1 in 5-year flood. The results show that the ‘action initiation flood level’ for more than 90% of the most susceptible watercourse crossings may be too low to be practical; at crossings where more than 48 hours of response time is required, flood monitoring may not significantly reduce hazard consequence as the action response plan may not be fully executed prior to pipeline failure. Pipeline failures are rare, and flood monitoring provides a useful monitoring approach for short-term management in many watercourses. However, these results demonstrate the importance of evaluating the required action response time relative to the available warning time for each watercourse crossing to confirm that flood monitoring will achieve the risk reduction expected by the operator. If flood monitoring is determined to be impractical because the action initiation flood is too low, it may provide justification for initiating other management actions (e.g., flood forecasting, purging prior to the flood season, or elevating such sites on the priority list for physical repairs).

Pipeline watercourse crossings are designed according to the best available industry/technical standards at the time of construction. Older pipeline systems were typically installed without the benefit of modern hydrotechnical engineering practices with little or no allowance for ongoing fluvial processes. The level of protection at specific crossings can deteriorate such that a relatively small flood (i.e. 1:10 year) can pose a significant integrity threat. The hazards associated with maintaining an existing crossing may not be acceptable for the continued safe operation of a pipeline; therefore, a pipe replacement may be required. The designing, planning, permitting, funding, contracting and construction of any pipe replacement option can require considerable time to implement. In most watercourses in Canada and the United States this means that the pipeline at risk, but not in an emergency situation, will likely go through at least one spring freshet and/or other seasonal peak flow event(s) prior to implementation of the pipe replacement project. Four examples of short term risk control measures are discussed for river crossings in and around central and northern British Columbia, Canada.

The Canadian Standards Association’s Publication Z662-07, Annex N provides guidelines for pipeline integrity management programs. Government agencies that regulate pipelines in Alberta, British Columbia and other Canadian jurisdictions are increasingly using Annex N as the standard to which pipeline operators are held. This paper describes the experience of Pembina Pipeline Corporation (Pembina) in implementing a geohazards management program to fulfill components of Annex N. Central to Pembina’s program is a ground-based inspection program that feeds a geohazards database designed to store geotechnical and hydrotechnical site information and provide relative rankings of geohazard sites across the pipeline network. This geohazard management program fulfills several aspects of the Annex, particularly: record keeping; hazard identification and assessment; risk assessment and reduction; program planning; inspections and monitoring; and mitigation. Pembina’s experience in growing their geohazard inventory from 65 known sites to over 1300 systematically inspected and catalogued sites in a span of approximately two years is discussed. Also presented are methods by which consultants and Pembina personnel contribute to the geohazard inspection program and geohazard inventory, and how the ground inspection observations trigger follow-up inspections, monitoring and mitigation activities.