A Spill Risk Assessment of the Enbridge Northern Gateway Project

adjustments ranging from 60 to 90%. The Bercha Group (2012b) concludes that risks
to public safety from a pipeline failure near the Casino at Whitecourt, Burns Lake, and
Kitimat are insignificant. Risks to residents and indoor and outdoor workers from a
pipeline releasing oil, condensate, or both are all below one in one million per year,
which the Bercha Group determines are acceptable levels of risk (Bercha Group
2012b).
Table 15: NEB Pipeline Failure Frequencies Adjusted Downward to Represent the ENGP
Pipeline
Failure
Causes
NEB Failure
Rate
(per 10,000
km-­‐year)
ENGP
Failure Rate
(per 10,000
km-­‐year)
Metal Loss 0.085 0.017 80%
Cracking 0.128 0.013 90%
External
Interference
Geotechnical
Failure
Material
Failure
0.021 0.021 -­‐ n/a
0.021 0.021 -­‐ n/a
0.021 0.009 60%
Other Causes 0.096 0.028 71%
Total 0.372 0.109 71%
Source: Bercha Group (2012b).
Downward
Adjustment Reason for Adjustment
Modern piggable pipelines are less
likely to fail than pipelines
represented in NEB data
Advanced coating technologies, low
stress design, and fatigue avoidance
through design and operations
Construction quality control,
inspection/testing after construction,
and operational surveillance
Estimated as same percentage as NEB
data (approx. 26%)
3.4. Summary of Tanker, Terminal, and Pipeline Spill Estimates for the ENGP
Table 16 presents a brief summary of spill return periods from the ENGP regulatory
application. For tanker spills, return periods range between 78 years for an
unmitigated oil or condensate spill of any size to 15,000 years for a mitigated oil spill
exceeding 40,000 m 3 . Terminal spills range from one unmitigated oil/condensate spill
of any size occurring every 29 years to one mitigated spill every 430 years for medium
oil spills releasing 10 to 1,000 m 3 of oil. Pipeline spills range from a leak releasing 94
m 3 every 2 years to a full-­‐bore rupture releasing 2,238 m 3 of oil every 239 years. The
ENGP regulatory application does not evaluate overall spill likelihood for tanker,
terminal, and pipeline spills. If spill return periods are evaluated collectively for the
entire ENGP, data from the ENGP application suggest that a tanker or terminal or
pipeline spill could occur once every 2 years 6 .
6 Return period calculated based on the following spill probabilities: (1) any size tanker spill; (2) any size
terminal spill, and; (3) pipeline leak.
15