A Spill Risk Assessment of the Enbridge Northern Gateway Project

are not amenable to internal inspection, contain material that did not undergo
inspection or quality control, and may have other characteristics associated with
more failures compared to modern pipelines. Based on these assumptions and
improved design and mitigation planning associated with modern pipelines,
Enbridge claims that the aforementioned factors decrease the likelihood of
pipeline failure and “were factored into failure frequency calculations for the
pipelines” (Enbridge 2010b Vol. 7b p. 3-­‐1). Enbridge does not provide proprietary
data from the NEB, fails to present any spill rates or spill frequencies calculated
from the NEB data, fails to explicitly explain how it adjusted incident frequencies,
and presents no evidence to justify the downward adjustments. Furthermore, it is
unclear whether the analysis includes the crude oil pipeline, condensate pipeline,
or both pipelines combined.
Similarly, the Bercha Group (2012b) estimates failure frequencies for the ENGP
pipeline based on historical pipeline rupture data from the NEB from 1991 to 2009
and makes several adjustments to the NEB data to incorporate various
improvements in pipeline operations. The authors fail to adequately justify
downward adjustments to several causes of pipeline ruptures including metal loss,
cracking, and material failure that result in a decrease in the NEB failure rate of
71%. First, the Bercha Group reduces the failure frequency for metal loss (internal
and external corrosion) by 80% based on a study by Muhlbauer (1996) entitled
Pipeline Risk Management Manual and discussions with experts, although the
authors provide no evidence to justify applying the reduction factor to the ENGP
pipeline system other than suggesting that the ENGP pipeline is modern. Second,
the Bercha Group reduces the failure frequency for cracking for the ENGP pipeline
system by 90% compared to the NEB data claiming that “advanced coating
technologies, low stress design, no tape coat, fatigue avoidance through design and
operations, is expected to virtually eliminate cracking potential” (Bercha Group
2012b p. 3.5) without referencing a single study, expert opinion, data set, or other
source of evidence. Third, the authors reduce the pipeline rupture frequency for
material failure by 60% due to quality control during construction, inspection,
testing, and other factors. Once again the report cites Muhlbauer (1996) but fails
to justify the application of the reduction factor to the ENGP pipeline system and
lacks evidence describing how the mitigation measures will achieve the stated
reductions in spill frequency.
Historical spill performance for Enbridge’s own pipeline system shows an increase
in spill frequency. According to data submitted by Enbridge (2012a) to the Joint
Review Panel for the ENGP providing the number of reportable spills per thousand
km of liquids pipeline, the frequency of spills increases from 1998 to 2010 (see
linear trendline in Figure 2). We recognize that this period is an insufficient amount
of time to evaluate historical spill data but Enbridge does not publicly provide
comprehensive spill data prior to 1998. We also recognize that spill data are not
broken down by age of pipeline to allow for a direct comparison of newer to older
pipelines. Nonetheless, Enbridge’s own data show an increase in spill frequency
that contradicts the downward adjustments that reduce spill frequencies in the
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