Found this in an engineering magazine. Very revealing.View attachment 5170View attachment 5171
Risks
Associated
with Tanker
Transports
for the
Northern
Gateway
Project
Brian Gunn PEng
Dr Ricardo O Foschi PEng
Dr Robert G Sexsmith PEng
A subject of current discussion and of upmost
importance to British Columbia is the proposal
submitted by Enbridge to the National Energy
Board regarding the construction of a pipeline from
Alberta to Kitimat, BC. This pipeline would carry diluted
bitumen (Dilbit) from Alberta’s oil sands. At Kitimat,
located at the head of Douglas Channel on the BC
coast, the crude oil would be loaded onto tankers and
shipped to Asia. The (Northern) sailing route between
Kitimat and the Pacific Ocean is long (approximately 160
nautical miles), and offers many navigational difficulties:
narrow channels, sharp bends and turns, high risks
associated with heavy fog, heavy wind and snow. The
transportation of heavy crude oil by supertankers along
this section of the British Columbia coastline is not only
fraught with risks regarding accidents and subsequent oil
spills, but each of these possible events will be associated
with environmental and economic consequences of
large proportions. Enbridge envisions a total of 220
tankers calling into Kitimat each year, some 70 of
them belonging to the VLCC class (Very Large Crude
Carriers). In addition, the oil tankers will be sharing
the same navigational channels with an estimated 432
Liquified Natural Gas (LNG) tankers and other vessels,
also calling annually at Kitimat. This estimate is provided
by Royal Dutch Shell PLC, Kitimat LNG and BC LNG.
The heavy nature of the bitumen transported facilitates
its sinking and makes surface clean-up difficult. This fact
was put in evidence following the 2010 spill of Dilbit from
an Enbridge pipeline in the state of Michigan, polluting
the Kalamazoo River. The damage and cost of cleaning up
that spill would pale in comparison with those associated
with a major spill from a supertanker in distress along the
route from Kitimat to the Pacific.
A group of professional engineers studied the Enbridge
submission and conducted an independent study of the
risks, not considering the pipeline itself but only the
risks involved in shipping the Dilbit from Kitimat to
the open ocean, along narrow, pristine channels, often
under adverse weather conditions. In addition, the
group considered the increased risks due to the heavy
LNG tanker traffic that will share the same navigational
channels.
The study by Enbridge is based on a benchmark worldwide
tanker accident probability obtained from a database
collected by Lloyds Register (Lloyds Register Fairplay
Database, LRFP, 2007). The route from Kitimat is divided
into segments, and the probability of a tanker incident
within each segment is obtained by using the benchmark,
adjusting it for the length of the particular segment, and
further modifying it by using scaling factors for local
conditions or navigational difficulties.
In order to obtain the risk of spills, Enbridge further
applied a factor of 0.327 to the probability of a tanker
incident (grounding or collision). The Enbridgecalculated
risk is further reduced by 80% if the navigation
is assisted by tugs. The final results are expressed as return
periods for spills of different sizes, and the Enbridge
study concludes that these risks are not higher than those
accepted already in other parts of the world for similar
operations.
It is difficult to validate the reduction factors of 0.327
or 80%, and the scaling factors derived from opinions of a
group of experts in Norway, and whether the very special
conditions of the BC coastline are really comparable to
other parts of the world.
Most importantly, the return periods obtained by
the Enbridge study are very low in comparison with
those normally required in the design of important civil
infrastructure. For example, the Enbridge study estimates
a return period of just 78 years for a spill of any size if no
tugs are used, and 250 years if navigation is assisted by tugs.
These return periods increase, respectively, to 200 and 550
years for substantial spills greater than 5,000 m3. The use of
return periods does not provide a complete picture of the
risk involved: we believe that it is more important to provide
the probability that there will be at least one spill during
the 50-year lifetime of the project. There is a mathematical
relationship between this probability and the associated return
period. Thus, the probability (in percent) associated with a
return period of 78 years is 47%, for 250 years is 18%, for 200
years is 22% and for 550 years is 9%.
It is our belief that these probabilities are too high and
represent an unacceptable level of risk. It seems incongruous that
British Columbians should accept these risks while, at the same
time, demanding a design target probability of 1.0 x 10-4 (a 10,000
year return period) for a Class 1 bridge collapse due to ship
collision (as in Canadian and US Bridge design codes), or using
a return period of nearly 2,500 years for a design earthquake.
Risk is not only probabilities but involves the corresponding
consequences, and the very high consequences from spills
demand much lower probabilities or much longer return periods.
The Enbridge study does not consider the increase in traffic due
to LNG tankers, which would further reduce the return periods
and increase the associated probabilities.
The question remains as to whether the return periods
estimated by the Enbridge study are themselves reliable, given
the inherent uncertainties when using different calculation
models. To assess this question, we considered two different,
independent, alternative calculation approaches. These are
described in detail in our submission to the Joint Review Panel
of the National Energy Board (https://www.neb-one.gc.ca/ll-eng/
livelink.exe?func=ll&objId=847750&objAction=browse)
In our study we considered, separately, incidents of
groundings and then collisions with other tankers. We obtained,
for example, a return period of 81 years for an incident of
grounding and 73 years for tanker collisions. These results imply a
return period of 38 years for incidents either from groundings or
from collisions (resulting in a 73% probability of at least one such
incident in a 50-year life for the project). Thus, our results agree
with the Enbridge study in that our estimates are also very short,
and find that they imply unacceptably high associated risks.
Our conclusion is then that tanker shipping of bitumen from
Kitimat is too risky and should not be approved. Furthermore,
our group believes that the impact of bitumen spills would be
catastrophic for:
• First Nation food supply and their culture;
• Nature and adventure-based tourism operations;
• Commercial fishery;
• The environment; and
• Safety of humans and wildlife in the vicinity of the spill area.
For these reasons, we believe that bitumen should not be
shipped as proposed by Enbridge. We further encourage all our
fellow professionals to read the different reports presented to the
Joint Review Panel of the National Energy Board, and to consider
this very important issue for the welfare of our province and to
join a reasoned discussion of the proposal. v
Brian Gunn PEng is a professional engineer with experience in
construction supervision and project management both in
Canada and overseas.
Dr Ricardo O Foschi PEng is Emeritus Professor of Civil
Engineering at the University of British Columbia, specializing
in probabilistic methods in engineering, including reliability
and performance-based design under reliability constraints,
particularly in earthquake engineering.
Dr Robert G Sexsmith PEng is Emeritus Professor of Civil
Engineering at the University of British Columbia, specializing
in probabilistic risk/safety and decisions for structural safety.
Hiswork has included consulting engineering for bridge design and erection, and ship collision risk assessment.
Risks
Associated
with Tanker
Transports
for the
Northern
Gateway
Project
Brian Gunn PEng
Dr Ricardo O Foschi PEng
Dr Robert G Sexsmith PEng
A subject of current discussion and of upmost
importance to British Columbia is the proposal
submitted by Enbridge to the National Energy
Board regarding the construction of a pipeline from
Alberta to Kitimat, BC. This pipeline would carry diluted
bitumen (Dilbit) from Alberta’s oil sands. At Kitimat,
located at the head of Douglas Channel on the BC
coast, the crude oil would be loaded onto tankers and
shipped to Asia. The (Northern) sailing route between
Kitimat and the Pacific Ocean is long (approximately 160
nautical miles), and offers many navigational difficulties:
narrow channels, sharp bends and turns, high risks
associated with heavy fog, heavy wind and snow. The
transportation of heavy crude oil by supertankers along
this section of the British Columbia coastline is not only
fraught with risks regarding accidents and subsequent oil
spills, but each of these possible events will be associated
with environmental and economic consequences of
large proportions. Enbridge envisions a total of 220
tankers calling into Kitimat each year, some 70 of
them belonging to the VLCC class (Very Large Crude
Carriers). In addition, the oil tankers will be sharing
the same navigational channels with an estimated 432
Liquified Natural Gas (LNG) tankers and other vessels,
also calling annually at Kitimat. This estimate is provided
by Royal Dutch Shell PLC, Kitimat LNG and BC LNG.
The heavy nature of the bitumen transported facilitates
its sinking and makes surface clean-up difficult. This fact
was put in evidence following the 2010 spill of Dilbit from
an Enbridge pipeline in the state of Michigan, polluting
the Kalamazoo River. The damage and cost of cleaning up
that spill would pale in comparison with those associated
with a major spill from a supertanker in distress along the
route from Kitimat to the Pacific.
A group of professional engineers studied the Enbridge
submission and conducted an independent study of the
risks, not considering the pipeline itself but only the
risks involved in shipping the Dilbit from Kitimat to
the open ocean, along narrow, pristine channels, often
under adverse weather conditions. In addition, the
group considered the increased risks due to the heavy
LNG tanker traffic that will share the same navigational
channels.
The study by Enbridge is based on a benchmark worldwide
tanker accident probability obtained from a database
collected by Lloyds Register (Lloyds Register Fairplay
Database, LRFP, 2007). The route from Kitimat is divided
into segments, and the probability of a tanker incident
within each segment is obtained by using the benchmark,
adjusting it for the length of the particular segment, and
further modifying it by using scaling factors for local
conditions or navigational difficulties.
In order to obtain the risk of spills, Enbridge further
applied a factor of 0.327 to the probability of a tanker
incident (grounding or collision). The Enbridgecalculated
risk is further reduced by 80% if the navigation
is assisted by tugs. The final results are expressed as return
periods for spills of different sizes, and the Enbridge
study concludes that these risks are not higher than those
accepted already in other parts of the world for similar
operations.
It is difficult to validate the reduction factors of 0.327
or 80%, and the scaling factors derived from opinions of a
group of experts in Norway, and whether the very special
conditions of the BC coastline are really comparable to
other parts of the world.
Most importantly, the return periods obtained by
the Enbridge study are very low in comparison with
those normally required in the design of important civil
infrastructure. For example, the Enbridge study estimates
a return period of just 78 years for a spill of any size if no
tugs are used, and 250 years if navigation is assisted by tugs.
These return periods increase, respectively, to 200 and 550
years for substantial spills greater than 5,000 m3. The use of
return periods does not provide a complete picture of the
risk involved: we believe that it is more important to provide
the probability that there will be at least one spill during
the 50-year lifetime of the project. There is a mathematical
relationship between this probability and the associated return
period. Thus, the probability (in percent) associated with a
return period of 78 years is 47%, for 250 years is 18%, for 200
years is 22% and for 550 years is 9%.
It is our belief that these probabilities are too high and
represent an unacceptable level of risk. It seems incongruous that
British Columbians should accept these risks while, at the same
time, demanding a design target probability of 1.0 x 10-4 (a 10,000
year return period) for a Class 1 bridge collapse due to ship
collision (as in Canadian and US Bridge design codes), or using
a return period of nearly 2,500 years for a design earthquake.
Risk is not only probabilities but involves the corresponding
consequences, and the very high consequences from spills
demand much lower probabilities or much longer return periods.
The Enbridge study does not consider the increase in traffic due
to LNG tankers, which would further reduce the return periods
and increase the associated probabilities.
The question remains as to whether the return periods
estimated by the Enbridge study are themselves reliable, given
the inherent uncertainties when using different calculation
models. To assess this question, we considered two different,
independent, alternative calculation approaches. These are
described in detail in our submission to the Joint Review Panel
of the National Energy Board (https://www.neb-one.gc.ca/ll-eng/
livelink.exe?func=ll&objId=847750&objAction=browse)
In our study we considered, separately, incidents of
groundings and then collisions with other tankers. We obtained,
for example, a return period of 81 years for an incident of
grounding and 73 years for tanker collisions. These results imply a
return period of 38 years for incidents either from groundings or
from collisions (resulting in a 73% probability of at least one such
incident in a 50-year life for the project). Thus, our results agree
with the Enbridge study in that our estimates are also very short,
and find that they imply unacceptably high associated risks.
Our conclusion is then that tanker shipping of bitumen from
Kitimat is too risky and should not be approved. Furthermore,
our group believes that the impact of bitumen spills would be
catastrophic for:
• First Nation food supply and their culture;
• Nature and adventure-based tourism operations;
• Commercial fishery;
• The environment; and
• Safety of humans and wildlife in the vicinity of the spill area.
For these reasons, we believe that bitumen should not be
shipped as proposed by Enbridge. We further encourage all our
fellow professionals to read the different reports presented to the
Joint Review Panel of the National Energy Board, and to consider
this very important issue for the welfare of our province and to
join a reasoned discussion of the proposal. v
Brian Gunn PEng is a professional engineer with experience in
construction supervision and project management both in
Canada and overseas.
Dr Ricardo O Foschi PEng is Emeritus Professor of Civil
Engineering at the University of British Columbia, specializing
in probabilistic methods in engineering, including reliability
and performance-based design under reliability constraints,
particularly in earthquake engineering.
Dr Robert G Sexsmith PEng is Emeritus Professor of Civil
Engineering at the University of British Columbia, specializing
in probabilistic risk/safety and decisions for structural safety.
Hiswork has included consulting engineering for bridge design and erection, and ship collision risk assessment.
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