A Spill Risk Assessment of the Enbridge Northern Gateway Project

7. To assess the impact of deficiencies in Enbridge’s analysis of tanker spill risk estimates,
we undertake additional sensitivity analysis based on the following scenarios:
a) Combining the four sensitivity parameters that were tested separately by Enbridge
(higher scaling factors for grounding, higher ship traffic, extended route, and higher
number of tankers)
b) Using incident frequencies derived from Lloyds Register Fairplay data without the
scaling factor adjustments for BC conditions that were done by Enbridge without
sufficient documentation or justification
c) Increasing conditional probabilities by five percentage points
d) Increasing tanker traffic to transport pipeline throughput of 1,125 kbpd (850 kbpd
of oil and 275 kbpd of condensate), which is the design capacity of the ENGP
e) Increasing tanker traffic associated with replacing very large crude carriers (VLCC)
with smaller Suezmax and Aframax tankers to transport throughput of 1,125 kbpd
of oil and condensate
f) Testing the combined effect of all the above parameters.
8. Enbridge did not complete any sensitivity analysis for oil or condensate spills at
Kitimat Terminal. To address this deficiency, we undertake a sensitivity analysis for
marine terminal operations based on the following scenarios:
a) Increasing tanker traffic to transport pipeline throughput of 1,125 kbpd (850 kbpd
of oil and 275 kbpd of condensate), which is the design capacity of the ENGP
b) Replacing larger VLCCs with smaller tankers to transport throughput of 1,125 kbpd
of oil and condensate that results in an increase in the number of tanker loadings.
9. Enbridge did not complete any sensitivity analysis for oil or condensate spills from the
ENGP pipelines. To address this deficiency, we undertake a sensitivity analysis based
on the following scenarios:
a) Using actual spill rates provided by Enbridge for Enbridge’s liquids pipeline system
for the years 2002-­‐2010
b) Using spill rates from the NEB for pipebody and operational leaks exceeding 1.5 m 3
or 9 barrels (bbl).
10. Table ES-­‐2 summarizes the impacts of the sensitivity analyses. The results provide a
range of possible spill rates for the ENGP and show that the impact of the alternative
scenarios on spill rates is significant:
• The tanker spill return period is between 23 and 196 years, well below Enbridge’s
mitigated tanker spill estimate of 250 years. This lower estimate of 23 to 196 years
still underestimates spill risk because it does not correct for all the deficiencies in
Enbridge’s spill risk methodology such as underreporting of incidents.
• The terminal spill return period is between 15 and 41 years compared to Enbridge’s
estimate of 62 years.
• The pipeline spill return period of 0.1 years (between 15 and 16 spills per year)
based on the actual spill rate experienced on the Enbridge liquids pipeline system
from 2002 to 2010 is 31 times higher than the 2 year return period estimated by
Enbridge.
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