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