TransCanada Pipelines Ltd. (TransCanada) operates approximately 37,000 km of natural gas gathering and transmission pipelines. Within the Alberta portion of this system there are almost 1100 locations where the pipeline(s) traverse slopes, primarily as the line approaches and exits stream crossings. In the past, the approach to managing the impact of slope movements on pipeline integrity has been reactive; site investigations and/or monitoring programs would only be initiated once the slope movements were sufficiently large so as to easily observe cracking or scarp development. In some cases these movements could lead to a pipeline rupture. To move to a proactive hazard management approach and to optimize the maintenance expenditure, TransCanada has developed a new slope assessment methodology. The objective of this methodology is to establish a risk-ranked list of slopes upon which maintenance decisions can be based. Using only internal and public information on site conditions as input to predictive models for rainfall-ground movement and pipe-soil interaction, a probability of pipeline failure can be generated for each slope. Estimates of risk using a consequence-matrix approach enabled the compilation of a risk-ranked list of hazardous slopes. This paper describes this methodology, and its implementation at TransCanada, and presents some of the results.

Numerous industry studies have characterized mechanical damage to be the pipeline industry’s largest single hazard. A proactive approach to preventing incidents due to mechanical damage is desirable. A process combining high-resolution satellite imagery with geomatic technologies such as GIS and image analyses is in the process of being demonstrated to be able to detect, georeference and characterize potentially injurious encroaching activities that may cause mechanical damage. The intrinsic advantages of a satellite imagery-enabled process include the high revisit frequencies (in comparison to typically used aerial patrol frequencies), the wider swath width of monitoring and the analysis -friendly digital nature of the imagery. The successful implementation of such a process will contribute to averting incidents in the many cases where One-call (Call before you dig) systems are not notified. In addition, as a by-product of the process, this service could assist in continuously surveying the right-of-way. Working with leading North American pipeline operators, via+ is developing and bringing to market commercial delivery models of this process. The elements of the process and the technologies current and anticipated capabilities are presented. Sample results of the process implementation are also presented.

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TransCanada owns and operates over 38,000 km of pipeline throughout North America, which cross over 3,300 slopes and 1,200 watercourses. Ground movements on slopes at river crossings are an important pipeline hazard across Canada and especially within the Alberta system. These movements have led to several past pipeline ruptures and the development of a relatively extensive slope monitoring program. Historically, ground movement impacts are an industry-wide problem. The results of a 1998 study by the Gas Research Institute reported that external force damage from natural forces, including ground movement, was responsible for approximately 12 percent of all incidents reported on U.S. onshore pipelines between 1985 and 1994. Of all natural force incidents, ground movement accounted for approximately 29 percent of the total, on average. Furthermore, of all fires or explosions resulting from pipeline incidents, ground movements were reported responsible for about 5 percent of the total. In a similar study of Alberta pipeline failures and incidents between 1980 and 1997 (EUB, 1998), ground movement was the cause of 56 ruptures, or 3.5 percent of the total. Until recently, monitoring of the progress of slope movements was reactive and undertaken in a traditional fashion, using primarily slope inclinometers and/or ground surveys. Recently, however, TransCanada has adopted a proactive approach for the management of ground movements. Consistent with the management of other pipeline hazards, such as corrosion, ground movements are cast in a risk-based framework. The application of DInSAR technology, Differential Interferometry applied to satellite synthetic aperture radar (SAR) imagery, fits well within the proactive approach and has proven successful in measuring ground movements on ROW slopes to sub-centimetre accuracy. In 2000, a Pipeline Research Committee International (PRCI) study was carried out on a TransCanada Right of Way (RoW) that compared conventional slope indicator readings with DInSAR technology and proved the capability of the technology. TransCanada has begun to use DInSAR technology in this program of monitoring Alberta slopes. Typically, TransCanada monitors slope movements at 53 sites with frequency of readings between bi-annually and 4 times per year using conventional methods. Since 2001, 14 slopes on the TransCanada system have been instrumented using DInSAR methods and monitoring of movements using interferometric methods is continuing.

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