Probability of Oil Spills from Tankers in Canadian Waters ... Coast Guard Tanker Spill Risk... ·...

Probability of Oil Spills from Tankers in Canadian Waters

by

SL Ross Environmental Research Ltd.Ottawa, Ontario

for

Canadian Coast GuardOttawa, Ontario

December 17, 1999

Executive Summary--Tanker Oil Spill Probabilities in Canada Page 1 of 5

Executive Summary

The study predicts the frequency of oil spills from tankers in various regions and areas of Canada. Theexpected spill rates (spills per year) are calculated by multiplying (1) the tonnage of oil loaded andunloaded at Canadian ports by (2) spill frequencies (spills per tonnes moved) derived from historicalstatistics.

Oil Traffic in Canada

Oil shipments by vessel are recorded by Statistics Canada. A summary of oil movements broken down byCanadian Coast Guard (CCG) region is shown in Table S1. The total amount of oil loaded and unloadedin Canadian ports in 1998 was about 72 million tonnes compared to 65 million tonnes five years ago. Theten-percent increase is primarily due to new movements of crude oil to the major transshipment terminalson the east coast, one at Whiffen Head in Placentia Bay, Newfoundland, to handle Hibernia oil, and oneat Port Hawkesbury to handle increasing amounts of foreign oil transshipped to ports in the northeast ofthe U.S.

Saint John, handling 16 millions tonnes of oil per year, remains the largest port by far in terms of oilmovements. Tankers of size 200,000 DWT and larger bring in crude oil from various foreign sources, andtankers of all sizes move product oil in and out of the port. This area, including the lower Bay of Fundywhich the tankers must transit to reach Saint John, is the busiest area in Canada for oil tanker traffic.

Calculating Spill Frequencies from Historical Statistics

Six spill size categories are selected for analysis, as listed below.

Exceptionally Large spills: >200,000 bbl (>27,800 tonnes)Extremely Large spills: >100,000 bbl (>13,900 tonnes)Very Large spills >10,000 bbl (>1390 tonnes)Large spills: >1000 bbl (>139 tonnes)Medium spills: 50 - 999 bbl (6.9 - 138.9 tonnes)Small spills: 1 - 49 bbl (0.14 - 6.89 tonnes)

Note that the top four categories are cumulative; for example, the large-spill category (>1000 bbl) includesthe very large, extremely large and exceptionally large spills.

Spill frequencies in terms of spills per billion barrels of oil moved have been calculated on the basis ofworldwide spill and shipping statistics (for crude oil) and Canadian statistics (for petroleum products suchas gasoline, diesel oil, heavy fuel oil, etc.). A summary of these is presented in Table S2.


Table S1. Tonnage of Petroleum Loaded and Unloaded at Canadian Ports in 1998

CCG Region Crude Oil Product Oils Grand TotalTonnes Tonnes Tonnes

Pacific Loaded 1,048,459 1,128,001.00 2,176,460

Unloaded 19 1,521,466 1,521,485Pacific Total 1,048,478 2,649,467 3,697,945

Central (Arctic) Loaded 156,557 156,557Unloaded 323,171 323,171

Central (Arctic) Total 479,728 479,728Central (Ont) Loaded 2,347,683 2,347,683

Unloaded 4,221 1,997,394 2,001,615Central (Ont) Total 4,221 4,345,077 4,349,298

Laurentian Loaded 588 3,239,786 3,240,374Unloaded 7,180,026 4,907,666 12,087,692

Laurentian Total 7,180,614 8,147,452 15,328,066Maritimes Loaded 5,807,635 8,296,053 14,103,688

Unloaded 18,167,067 4,065,711 22,232,778Maritimes Total 23,974,702 12,361,764 36,336,466

Newfoundlanda Loaded 3,535,731 3,277,058 6,812,789Unloaded 3,634,269 1,681,731 5,316,000

Newfoundland Total 7,170,000 4,958,789 12,128,789Grand Total 39,378,015 32,942,277 72,320,292

a.1999 estimate for Grand Bank/Whiffen Head


Table S2. Spill Frequencies (Inbound or Outbound Journeys) and Average and Mean Spill Sizes for Six Categories

Spill Category

Crude Oil Spills Product Oil Spills

Spill Frequencyb Spill Size Spill Frequencyb Spill Size

spills/ 109 bblloaded orunloaded

spills/109 Tloaded orunloaded

Average Median spills/ 109 bblloaded orunloaded

spills/109 Tloaded orunloaded

Average Median

ExceptionallyLarge, >200,000bbl (>27,800 T)

0.050a 0.36 539,000 bbl(74,900 T)

382,000 bbl(53,000 T)

0 0 0 0

Extremely Large,>100,000 bbl(>13,900 T)

0.155 1.12 374,000 bbl(51,900 T)

244,000 bbl(33,800 T)

0.083 0.594 108,000bbl

(15,000T)

108,000bbl

(15,000T)

Very Large,>10,000 bbl(>1390 T)

0.36 2.59 183,000 bbl(25,5000 T)

73,300 bbl(10,200 T)

0.167 1.20 79,000bbl

(11,000T)

79,000bbl

(11,000T)

Large, >1000 bbl(>139 T)

0.65 4.68 104,000 bbl(14,500 T)

15,000 bbl(2100 T)

2.5 18 6320 bbl(878 T)

1688 bbl(234 T)

Medium, 50-999bbl (6.9-138.9 T)

1.5 10.8 233 bbl(32 T)

132 bbl(18 T)

12.3 88.6 216 bbl(30 T)

124 bbl(17 T)

Small, 1-49 bbl(0.14-6.89 T)

7.8 56.2 10.4 bbl(1.4 T)

5 bbl(0.7 T)

36 260 10.3 bbl(1.4 T)

5.8 bbl(0.8 T)

a. Numbers kept at three significant digits for calculation purposesb. These values are half the spill frequencies normalized by volumes moved because a movement includes a loading and an unloading.


Predicting Spill Rates for Tankers in Canada

The frequency numbers in Table S2 are combined with the shipping statistics in Table S1 to producestatistics on the number of spills per year that are likely to happen in each CCG region for the sixcategories of spill size range. The results are shown in Table S3. Not included in the table is the spill riskfor the movement of crude oil into Puget Sound just south of Vancouver Island. The volume of oil movedis about 25 million tonnes per year. The estimated annual spill rate of large spills (>1000 bbl) wascalculated to be 0.061 spills per year (one such spill every 16 years).

The following conclusions can be made about the risk of oil spills across the country.

1. The Maritimes region by far has the greatest risk of spills. Half of the expected spills in the countryare in this region. The risk picture is even worse than it seems from Table S3 because tankers withdeliveries of crude oil to Quebec must first transit and put at risk the Maritimes Region. It is notsurprising that the two largest oil spills in Canadian history, the Arrow spill in 1970 (about 15,000tonnes) and the Kurdistan spill in 1979 (about 7,000 tonnes) occurred in this region.

2. The Newfoundland region would be ranked number two even though ports in the LaurentianRegion load and unload more oil. The reason is twofold. First, the volume of oil moved in theregion is relatively large and is growing quickly as the oil industry produces more Grand Bank oiland moves it by tanker to Whiffen Head through Placentia Bay. Second, much traffic to the Quebecand Maritime ports must pass relatively close to the coast of Newfoundland, and recent experienceswith oiled birds washing ashore from illegal dumps from some of this traffic show that theprevailing currents and winds can indeed push a large spill to the south coast of the province.

3. Quebec would be next for obvious reasons: a substantial amount of oil is moved in the province,the second largest amount in the country. The region is also troubled by having to deal with spillsin the St. Lawrence River. Spills in rivers are always more difficult to control than spills in lowcurrent situations, and spills in rivers can be forced ashore quickly by winds, and smear longstretches of coastline.

4. For the same reason the St. Clair River in Ontario is a hot spot because a substantial amount of oilis moved in the river, to and from Sarnia (1.5 million tonnes loaded and unloaded in 1998), and theriver has very high currents, making spill control very difficult.

5. The Pacific region would have about double the risk of the Central region, and even more becauseof the U.S. traffic to Puget Sound.

6. The chance of a large spill (>1000 bbl) for the country as a whole is about one per year. Theaverage large-spill size is in the 10,000 tonne range and the median spill size is in the 2000 tonnerange. The spill of particular interest to the Coast Guard is likely to be the very large spill (>10,000bbl) because this spill size range produces a median spill size of about 10,000 tonnes. This has beenthe size of interest for planning purposes in Canada ever since the Brander-Smith panel exercise10 years ago, and is the average spill size of the two largest spills already experienced by Canada.This spill size has a probability of occurrence of approximately one in seven years.


Table S3. Number of Spills per Year for Canadian Coast Guard Regions

Number of Spills per YearVolume Size Range Size Range Size Range Size Range Size Range Size Range

CCG Region (106 tonnes) 1 - 49 bbl 50 - 999 bbl > 1,000 bbl > 10,000 bbl > 100,000 bbl > 200,000 bblcrude 5.616E-02 1.080E-02 4.680E-03 2.592E-03 1.116E-03 3.600E-04

product 2.592E-01 8.856E-02 1.800E-02 1.20E-03 5.976E-04 0.00E+00

PacificCrude Oils 1.048 0.059 0.0113 0.0049 2.72E-03 1.17E-03 3.77E-04

Product Oils 2.649 0.687 0.2346 0.0477 3.19E-03 1.58E-03 0.00E+00Pacific Total 3.698 0.746 0.2460 0.0526 0.0059 0.0028 0.0004

Central (Arctic)Crude Oils 0.000 0.000 0.0000 0.0000 0.00E+00 0.00E+00 0.00E+00

Product Oils 0.480 0.124 0.0425 0.0022 5.77E-04 2.87E-04 0.00E+00Central (Arctic) Total 0.480 0.124 0.042 0.002 5.77E-04 2.87E-04 0.00E+00

Central (Ont)Crude Oils 0.004 0.000 0.0000 0.0000 1.09E-05 4.71E-06 1.52E-06

Product Oils 4.345 1.126 0.3848 0.0782 5.22E-03 2.60E-03 0.00E+00Central (Ont) Total 4.349 1.126 0.3848 0.0782 5.24E-03 2.60E-03 1.52E-06

LaurentianCrude Oils 7.181 0.403 0.0776 0.0336 1.86E-02 8.01E-03 2.88E-06

Product Oils 8.147 2.112 0.7215 0.1467 9.80E-03 4.87E-03 0.00E+00Laurentian Total 15.328 2.515 0.7991 0.1803 2.84E-02 1.29E-02 2.88E-06

MaritimesCrude Oils 23.975 1.346 0.2589 0.1122 6.21E-02 2.68E-02 8.63E-03

Product Oils 12.362 3.204 1.0948 0.2225 1.49E-02 7.39E-03 0.00E+00Maritimes Total 36.336 4.551 1.3537 0.3347 7.70E-02 3.41E-02 8.63E-03

NewfoundlandCrude Oils 7.170 0.403 0.0774 0.0336 1.86E-02 8.00E-03 2.58E-03

Product Oils 4.959 1.285 0.4392 0.0893 5.96E-03 2.96E-03 0.00E+00Newfoundland Total 12.129 1.688 0.5166 0.1228 2.455E-02 1.097E-02 2.581E-03

Total for Canada 72.320 10.750 3.343 0.771 0.142 0.064 0.01211 per year 3 per year one per year one in 7 years one in 16 years one in 86 years

<0 .5 Tonnes < 2 Tonnes 2100 Tonnes 10,200 Tonnes 33,800 Tonnes 53,000 TonnesMedian Spill Size

Table of Contents

Executive Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 1 of 5

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.1 Objective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2 Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

2. Study Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23. Oil Traffic in Canada . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34. Overview of Tanker Oil Spills . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125. Determination of Spill Probabilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

5.1 Spill Size Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155.2 Exceptionally Large Crude Oil Spills . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

5.2.1 Historical Record . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165.2.2 Exceptionally Large Crude Oil Spills in Canada . . . . . . . . . . . . . . . . . . . . . . . . . 18

5.3 Extremely Large, Very Large and Large Crude Oil Spills . . . . . . . . . . . . . . . . . . . . . . . 185.3.1 Historical Record . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185.3.2 Large Crude Oil Spills in Canada . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

5.4 Special Case of U.S. West Coast Crude Oil Traffic . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225.5 Small and Medium Crude Oil Spills . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235.6 Spills from Tankers Carrying Petroleum Products other than Crude Oil . . . . . . . . . . . . 23

5.6.1 Large Product Oil Spills from Tankers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255.6.2 Very Large Product Oil Spills from Tankers . . . . . . . . . . . . . . . . . . . . . . . . . . . . 275.6.2 Medium and Small Product Oil Spills . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

5.7 Summary of Spill Frequencies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 286.Calculation and Analysis of Regional Spill Rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

6.1 Relative Risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 306.2 National Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

7. References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

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1. Introduction

1.1 Objective

The purpose of the study is to predict the frequency of oil spills from tankers in various regions andareas of Canada. The information can be used to identify the regions and areas of Canada that shouldbe the focus of oil spill contingency planning efforts for the Canadian Coast Guard (CCG). Theinformation can also be helpful in deciding the level of effort required.

The analysis is an update of an unpublished study conducted by SL Ross for the CCG in 1989entitled "Expected Frequency of Oil Spills from Tankers in or Near Canadian Waters". Versions ofthis were also done for the Brander-Smith spill review panel (1990) and the Canadian PetroleumProducts Institute (1991). The focus of these studies and the current study is on particularly largespills.

1.2 Units

This report uses two units for oil amounts – barrels and tonnes. The international oil and gas industryprimarily works with the oil volume unit of petroleum barrel (which is different than a U.S. barreland a British barrel). There are 6.29 petroleum barrels in one cubic metre (m3). To convert betweenbarrels and tonnes one needs the specific gravity of the oil because a barrel is a measure of volumeand a tonne is a measure of mass. A rough conversion for this study is 7.2 petroleum barrels pertonne of oil. This assumes an average oil specific gravity of 0.87 or an API gravity of 30o.

The main reason for using the units of barrels in the study is that most spill statistics are taken frompublications of the U.S. Minerals Management Service which works exclusively with the oil volumeunits of barrels.

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2. Study Approach

There are numerous studies on marine oil-spill probability, but these have not used the samedatabases and statistical approaches and hence have produced dissimilar results. The approach usedhere is very simple. It assumes that there a direct correlation between spill frequency and the amountof oil moved by vessel. This means, for example, that a system that has twice as much oil traffic asanother system will be expected to have twice as many spills.

The approach is adopted directly from a method developed by the U.S. Minerals ManagementService (MMS) for analysing large, crude oil tanker spills. Since 1983 MMS has analysed worldwidetanker spills of crude oil in depth to determine the best risk exposure to use in normalizing spill data.After analysing spill frequencies in terms of voyage length, ship size, oil volumes transported, spilllocation, etc., it was concluded that a simple exposure of oil volumes transported (e.g., billions ofbarrels) is as good as any in predicting risk. The most recent detailed reports from MMS on thesubject are provide in Anderson and Lear 1994 and Anderson and LaBelle 1994.

Canada has not experienced many large marine oil spills, so for spill-prediction purposes one mustlook elsewhere for a good database on large spills. There is indeed a good database on large tankerspills that have taken place on a worldwide basis, and this can be used as a basis for estimatingCanadian large-spill frequencies. Because worldwide statistics are used, it is assumed that tankersafety and navigational risks in Canada are no different than those in the rest of the world.

For relatively small spills, the situation is reversed: whereas worldwide small-spill statistics areunreliable, the Canadian government maintains a database on small spills, and it is this that is usedin the present study.

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3. Oil Traffic in Canada

As stated, the expected spill frequencies for a given port area will be calculated on the basis of theknown amount of oil moved in the port, that is, the amount of oil loaded at the port and moved away,and the amount of oil moved into the port and unloaded. Oil shipments by vessel are recorded byStatistics Canada. On a annual, port-by-port basis the information includes: (1) the amount and typeof oil delivered (from another Canadian port or from a foreign source); and (2) the number ofshipments involved. The raw data provided by Statistics Canada are shown in four separate files inAppendices A1 to A4, involving:

A1. Domestic movements of all petroleum oils by port of unloading;A2. Domestic movements of all petroleum oils by port of loading;A3. International movements of all petroleum oils by port of unloading; and A4. International movements of all petroleum oils by port of loading.

The oil types include crude oil and various product oils, including gasoline, diesel oil, light fuel oil,fuel oil no.1, fuel oil no.2, aviation turbine fuel, kerosene, heavy fuel oil, and bituminous mixtures.For our purposes we assume that the risk of oil spills is identical if (a) the oil is moved into a portand unloaded or (b) the oil is loaded at the port and moved off. As well, we assume that once inCanadian waters, there is no difference in risk between ships arriving from international ports andships from domestic ports. There is a difference, however, in the risk associated with crude oilamounts moved and product oil amounts moved, as will be shown later (this has to do with the sizeof vessels involved). For this reason we keep these statistics separate.

The final results are shown in two tables – Tables 1 and 2. Other arrangements of the raw data thatwere made but not used in the final analysis are included in Appendices A5 to A12.

Table 1 shows the amount of oil shipped in and out of Canadian ports, sorted by CCG Region, andby oil type (crude oil or petroleum product). Table 2 is the same as Table 1 but shows a breakdownfor the ports in each region. The data for Grand Bank and Whiffen Head, Newfoundland, are takenfrom 1999 statistics, for reasons explained below.

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Table 1. Tonnage of Petroleum Loaded and Unloaded at Canadian Ports in 1998

CCG Region Crude Oil Product Oils Grand TotalTonnes Tonnes Tonnes

Pacific Loaded 1,048,459 1,128,001.00 2,176,460

Unloaded 19 1,521,466 1,521,485Pacific Total 1,048,478 2,649,467 3,697,945

Central (Arctic) Loaded 156,557 156,557Unloaded 323,171 323,171

Central (Arctic) Total 479,728 479,728Central (Ont) Loaded 2,347,683 2,347,683

Unloaded 4,221 1,997,394 2,001,615Central (Ont) Total 4,221 4,345,077 4,349,298

Laurentian Loaded 588 3,239,786 3,240,374Unloaded 7,180,026 4,907,666 12,087,692

Laurentian Total 7,180,614 8,147,452 15,328,066Maritimes Loaded 5,807,635 8,296,053 14,103,688

Unloaded 18,167,067 4,065,711 22,232,778Maritimes Total 23,974,702 12,361,764 36,336,466

Newfoundlanda Loaded 3,535,731 3,277,058 6,812,789Unloaded 3,634,269 1,681,731 5,316,000


a.1999 estimate for Grand Bank/Whiffen Head

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Table 2. Tonnage of Petroleum Loaded and Unloaded at Canadian Ports in 1998

Crude Oil Product Oils Grand Total

CCG Region Port Pacific BELLA COOLA Unloaded 3,840 3,840

CAMPBELL RIVER Unloaded 38,532 38,532COURTENAY Unloaded 9,814 9,814CROFTON Unloaded 6,706 6,706EAST COAST VANC ISL Unloaded 173,516 173,516ESQUIMALT Unloaded 2,129 2,129FITZ HUGH SOUND Unloaded 386 386GOLD RIVER Loaded 4,794 4,794

Unloaded 10,274 10,274NANAIMO Unloaded 104,632 104,632NEW WESTMINSTER Loaded 57,508 57,508

Unloaded 152 152PORT ALICE Unloaded 42,959 42,959PORT MCNEILL Unloaded 6,776 6,776POWELL RIVER Unloaded 28,346 28,346QUEEN CHARLOTTE ISLA Unloaded 587 587SKIDEGATE Unloaded 17,761 17,761VANCOUVER Loaded 1,048,459 1,065,699 2,114,158

Unloaded 19 957,256 957,275VICTORIA Unloaded 117,800 117,800

Pacific Total 1,048,478 2,649,467 3,697,945

Central (Arctic) ALL BEACH Unloaded 2,172 2,172ARCTIC BAY Unloaded 20,093 20,093BELCHER ISLANDS Unloaded 1,495 1,495BROUGHTON ISLAND Unloaded 24,350 24,350CAPE ASTON Unloaded 20,093 20,093CAPE DORSET Unloaded 2,919 2,919CHURCHILL Loaded 24,856 24,856

Unloaded 18,219 18,219FROBISHER BAY Unloaded 54,295 54,295IGLOOLIK Unloaded 4,085 4,085INUVIK Loaded 315 315

Unloaded 21,226 21,226LAKE HARBOUR Unloaded 1,456 1,456N.W.T. NES Loaded 99,949 99,949

Unloaded 117,481 117,481PANGNIRTUNG Unloaded 4,573 4,573REPULSE BAY Unloaded 1,544 1,544RESOLUTE BAY Unloaded 14,087 14,087TUKTOYAKTUK Loaded 31,437 31,437

Unloaded 8,314 8,314YELLOWKNIFE Unloaded 6,769 6,769

Central (Arctic) Total 479,728 479,728

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Table 2. Tonnage of Petroleum Loaded and Unloaded at Canadian Ports in 1998 (cont.)


Port Central (Ont) BRITT Unloaded 81,227 81,227

CLARKSON Loaded 75,773 75,773Unloaded 188,624 188,624

HAMILTON Loaded 154 154Unloaded 2 191,499 191,501

KINGSTON Unloaded 24,322 24,322KINGSVILLE Loaded 447 447MARATHON Unloaded 25,434 25,434MORRISBURG Unloaded 51,456 51,456NANTICOKE Loaded 860,999 860,999

Unloaded 124,149 124,149OAKVILLE Loaded 257,733 257,733

Unloaded 167,384 167,384OSHAWA Loaded 3,425 3,425

Unloaded 45,362 45,362PELEE ISLAND Unloaded 447 447PORT COLBORNE Loaded 3,631 3,631

Unloaded 28,394 28,394PORT STANLEY Loaded 5,479 5,479

Unloaded 18,212 18,212SARNIA Loaded 1,121,411 1,121,411

Unloaded 4,219 495,327 499,546SAULT STE-MARIE Unloaded 279,297 279,297THUNDER BAY Unloaded 84,024 84,024TORONTO Loaded 6,028 6,028

Unloaded 79,759 79,759WINDSOR ONT. Loaded 12,603 12,603

Unloaded 112,477 112,477Central (Ont) Total 4,221 4,345,077 4,349,298

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Port Crude Oil Product Oils Grand Total

Laurentian BAIE COMEAU Loaded 8,673 8,673Unloaded 157,404 157,404

BLANC SABLON Unloaded 3,676 3,676CHANDLER Unloaded 29,158 29,158GASPE Unloaded 71,267 71,267HAVRE ST-PIERRE Unloaded 4,794 4,794ILES DE LA MADELEINE Unloaded 63,402 63,402MATANE Loaded 6,719 6,719

Unloaded 88,822 88,822MONTREAL/CONTRECOEULoaded 588 1,524,245 1,524,833

Unloaded 579 2,587,419 2,587,998NEW RICHMOND Unloaded 48,135 48,135PORT ALFRED Unloaded 101,607 101,607PORT CARTIER Unloaded 130,580 130,580QUEBEC NORTH Loaded 580 580

Unloaded 54,969 54,969QUEBEC NORTH SHORE Loaded 50 50

Unloaded 50 50QUEBEC/LEVIS Loaded 1,689,458 1,689,458

Unloaded 7,179,447 815,042 7,994,489RIMOUSKI Unloaded 212,957 212,957SEPT-ILES/PTE. NOIRE Loaded 10,061 10,061

Unloaded 441,137 441,137TROIS-RIVIERES Unloaded 84,271 84,271VALLEYFIELD Unloaded 12,976 12,976

Laurentian Total 7,180,614 8,147,452 15,328,066

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Port Maritimes BAYSIDE Loaded 10,633 10,633

BELLEDUNE Unloaded 75,301 75,301CHARLOTTETOWN Loaded 6,178 6,178

Unloaded 369,784 369,784CHATHAM Unloaded 176,734 176,734COHASSET Loaded 818,421 818,421DALHOUSIE Unloaded 806,287 806,287GRAND MANAN Unloaded 5,569 5,569HALIFAX Loaded 4,933 1,454,267 1,459,200

Unloaded 3,662,826 1,140,441 4,803,267NS NES/N.E. NDA Loaded 12,562 12,562PEI NES/I.P.E NDA Unloaded 16,844 16,844PORT HAWKESBURY Loaded 4,984,281 287,974 5,272,255

Unloaded 5,666,188 330,393 5,996,581SAINT JOHN Loaded 6,524,439 6,524,439

Unloaded 8,031,766 1,594,111 9,625,877SYDNEY Unloaded 299,969 299,969YARMOUTH Unloaded 56,565 56,565

Maritimes Total 23,974,702 12,361,764 36,336,466

Newfoundlanda BOTWOOD Unloaded 124,245 124,245CLARENVILLE Unloaded 9,933 9,933COME BY CHANCE Loaded 3,174,237 3,174,237

Unloaded 3,321,005 140,845 3,461,850CORNER BROOK Unloaded 246,166 246,166DILDO Loaded 1,964 1,964FORTUNE Loaded 29 29GOOSE BAY Unloaded 80,151 80,151GRAND BANK Loaded 2,769,988 2,769,988HOLYROOD Loaded 95,779 95,779

Unloaded 561,898 561,898LEWISPORTE Unloaded 93,544 93,544MARYSTOWN Unloaded 14,724 14,724NFLD NES/T.N. NDA Unloaded 34,365 34,365PORT AUX BASQUES Unloaded 25,728 25,728ST JOHNS Loaded 452,480 5,049 457,529

Unloaded 324,760 324,760STEPHENVILLE Unloaded 25,372 25,372WHIFFEN HEAD Unloaded 313,264 313,264WIFFENHEAD Loaded 313,263 313,263


a. 1999 estimate for Grand Bank and Whiffen Head

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A similar analysis of oil movements in 1994 was performed by Consulting and Audit Canada (CAC)in an oil spill risk study performed for the Canadian Coast Guard in 1996 (see Figure 3.1, page 27in CAC 1996). The following is a discussion of the similarities and differences in oil movementsbetween 1994 and 1998.

Total oil movements have increased from 65 million tons to 76 million tonnes. The differences inthe major ports or loading areas are shown in Table 3. These ten port areas represent about 85% ofthe total amount of oil moved.

Hibernia Oil. The first major change from 1994 to 1998 is that the Hibernia field off Newfoundlandon the Grand Banks has come on stream and is producing some 2.8 million tonnes of oil per year.The transshipment terminal at Whiffen Head did not become operational until October 1998, so mostof the oil produced in 1998 was shipped from the Hibernia facility directly to U.S. ports. Currently,(on the basis of the record for the first six months of 1999), approximately 2/3 of Hibernia oil isbeing moved directly (in 115,000 DWT tankers) to U.S. ports and 1/3 to Whiffen Head where it isstored temporarily and then shipped in smaller vessels (78,000 DWT) to U.S. ports. Currently, then,the Hibernia facility loadings and the Whiffen Head oil movements account for about 7 milliontonnes of oil per year, which is about 10 per cent of the total oil movements in Canada (and about20% of the crude oil movements). It is recognized that the oil moved at Whiffen Head is countedtwice (once for unloading and once for loading), but from an oil spill risk view this is correct becauseeach of these movements is assumed to represent the same risk.

Port Hawkesbury. The other big change in movements is the situation at the transshipment terminalat Port Hawkesbury. Here the main activity is bringing in crude oil from Europe in tankers of size250,000 DWT (20 shipments from Norway in 1998) and transferring it to smaller tankers in the80,000 DWT range. These smaller tankers then move oil to ports on the northeast coast of the U.S.Port Hawkesbury is used in this way because the arriving tankers are either too large to beaccommodated in northeast U.S. ports or their design does not conform to new U.S. safetyregulations.

In any case, this transshipment activity has increased by over 100% since 1994. This represents arelatively large spill risk, inasmuch as the 11 million tonnes moved annually is 14% of all oil movedin Canada by vessel, and 26% of the crude oil moved by vessel. As with the case of Whiffen Head,the same oil is counted twice, but this makes sense for spill risk analysis purposes.

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Table 3. Oil Loadings/Unloadings at the Top Ten Canadian Ports, 1998 compared to 1994

Port Oil loaded and unloaded, thousand tonnes

1998 1994b

Saint John 16,150 17,826

Port Hawkesbury 11,269 5,142

Quebec 9,684 10,439

Come by Chance 6,636 5,000

Halifax 6,262 6,909

Montreal 4,113 5,450

Grand Bank (Hibernia) 4,067a 0

Vancouver 3,071 2,634

Whiffen Head (Nfld. Transshipment Terminal) 3,047a 0

Sarnia 1,621 1,432

TOTAL 65,920 54,832a. First-half 1999 data x 2b. Source: CAC 1996

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Saint John. All of the other major ports, including Saint John, moved about the same amount of oilin 1998 compared to 1994. Again, Saint John is the largest port by far in terms of oil movements.Tankers of 200,000 DWT and larger bring in crude oil from various foreign sources, and tankers ofall sizes move product oil in and out of the port. This area, including the lower Bay of Fundy whichthe tankers must transit to reach Saint John, must be considered the highest risk area in the country,at least as far as oil movements are concerned.

Quebec City. The traffic to Quebec City/Levis is also a special concern and not only because theoil volumes moved are very large. The added concern relates to the fact that crude oil carriersdestined for Quebec must travel a great distance in relatively close proximity to the Canadiancoastline. Ships must first sail in waters just south of Newfoundland, transit the Cabot Strait, movealong the Gulf of St. Lawrence, and finally must negotiate the St. Lawrence River itself. This routeadds extra risk to the Maritimes and Newfoundland regions. This study does not attempt toquantitatively account for this transit traffic and the extra risk posed by it. Accordingly, at the endof the quantitative risk analysis that follows, we re-visit the issue and discuss it in qualitative terms.

West Coast Crude Oil Traffic in U.S. Waters. A similar "transit" problem exists on the west coast.A very large amount of crude oil from Alaska moves down the west coast of Canada and aproportion is delivered to ports in Washington State (the rest moves further south).The total amountmoved into Washington ports in Puget Sound is 27.7 million tons (25.1 tonnes) (see Table B1 inAppendix B). This is about the same amount moved into Nova Scotia and New Brunswickcombined. The traffic is not a problem as it moves down the Canadian coast because tankers keepreasonably far offshore, but the tankers must travel into the Strait of Juan de Fuca, very close toVancouver Island, and into Puget Sound.

This traffic, an obvious risk to Canada, is a special case that must be handled separately, as it is inthe analysis presented in Section 5.

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4. Overview of Tanker Oil Spills

Before proceeding directly to the quantitative assessment of spill probability, it useful to review thecauses and sources of ship-based spills as seen from a worldwide perspective.

The focus of the analysis is on spills from tankers. Spill sizes from non-tank ships are much smallerthan those from tankers, actually 15 times smaller on average (as shown in Table B2 in AppendixB). Because of this, more attention is usually given to tanker spills in terms of governmentregulations, contingency planning and statistical record-keeping. There is an excellent body of spillstatistics related to the tanker business, especially involving crude oil, but much less related to spillsfrom other ships. Accordingly, it is convenient here to deal with tanker spills exclusively.

Tanker accidents that lead to spills can be divided into those that occur as a result of (1) operationsin ports or oil terminals and (2) casualties involving groundings, collisions, explosions, and the like.As shown in Table 4 (from ITOPF 1999) most spills from tankers result from routine operations,such as loading, discharging and bunkering, that normally occur in ports or at terminals. The majorityof these operational spills are small, with some 85 per cent involving quantities less than 50 barrels(7 tonnes). Accidents involving collisions and groundings generally give rise to much larger spills.It is these large spills resulting from casualties that are of prime interest in this study.

It is calculated from Table 4 that 76% of accidents leading to the larger spills (>5000 barrels)resulted from collisions and groundings, and 24% from hull failures, fires and explosions. Similarstatistics are shown in Table 5. (This is from a classic study by Card et al. that is old (1975) but stillof relevance today.) As shown, in the four-year period of 1969-1973 there were over 3000 recordedaccidents of tankships, 452 of which led to the discharge of over 770,000 tons of oil into the marineenvironment. This averaged about two accidents per day worldwide. The percentage of casualtiesthat involved collisions, rammings and groundings is seen to be 65%. Also seen is the fact that about14 % of tanker casualties resulted in some outflow of oil (452/3183). This number is consistent withthe results of more recent studies on tanker accidents (CCG 1991, USCG 1994).

Fortunately, the safety record of tankers have improved considerably since the early 1970s. This isshown in Figure 1 (also from ITOFP 1999). It is seen that the number of tanker spills over 700tonnes in size (5000 barrels) in the 1970s averaged about 24 spills per year, and in the 1980s theaverage was about 8 spills per year, a three-fold decrease.

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Figure 1. Number of Spills over 700 tonnes

0

5

10

15

20

25

30

35

40

Year

Num

ber o

f spi

lls

1970-79

24.1 spills per year

on average

1980-89

8.8 spills per year

on average

1990-98

7.6 spills per year

on average

Source: ITOPF 1999

Table 4. Incidence of Tanker Spillsa by Cause, 1974-1998

<50 barrels or <7 tonnes

50-5000 bblor 7-700 tonnes

>5000 bblor >700 tonnes

Total

OPERATIONS

Loading/discharging 2756 291 17 3064

Bunkering 541 24 0 565

Other operations 1162 47 0 1209

ACCIDENTS

Collisions 150 229 85 464

Groundings 219 191 103 513

Hull failures 552 73 40 665

Fires & explosions 149 16 19 184

OTHER 2213 159 34 2406

Total 7742 1030 298 9070Source: ITOPF 1999 – www.itopf.coma. Database includes crude oil spills and product oil spills

Table 5. Tankships (over 3,000 DWT) Involvements 1969-1973a

InvolvementType

TotalNumber of

Involvements

Percent ofInvolvements

NumberResulting in

Outflow

Percent ofOil Outflow

Involvements

Amount ofOil Outflow

(LT)

Number ofTotal Losses

Outflowfrom Total

Losses

Breakdown 355 11 11 2 29,940 2 29,350

Collision 744 24 126 28 185,088 7 140,779

Explosion 104 3 31 7 94,803 11 88,780

Fire 197 6 17 4 2,935 1 1,250

Grounding 790 25 123 27 230,806 12 134,449

Ramming 473 15 46 10 13,645 0 0

Structural Failure 515 16 94 21 339,181 15 322,519

Other 5 - 4 1 54,911 3 54,790

TOTALS 3,183 100 452 100 951,309 51 771,917Source: Card et al. 1975

a. Database includes both crude oil tankers and product oil tankers

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5. Determination of Spill Probabilities

The end objective is to calculate spill probabilities, or predictions of spills per year, for the oil trafficreported in Section 3. The first step is to derive, for spills of various size, spill frequencies in termsof spills per billion barrels of oil moved (or billion tonnes of oil moved). This is done in this chapter.The next step is simply to multiply the tonnage moved per year by the calculated spill frequencies.This yields the predicted spill rates. In the analysis, crude oil and petroleum product are consideredseparately for a number of reasons explained later.

5.1 Spill Size Classification

For convenience, six spill size categories are selected and analysed. The first two categories are for“exceptionally large” and "extremely large" spills, arbitrarily defined as spills larger than 200,000barrels (27,800 tonnes) and 100,000 bbl (13,900 tonnes) respectively. Good worldwide statistics areavailable for such spills. The third and fourth categories are for “very large” and “large” spills,defined by the U.S. Minerals Management Service as spills larger than 10,000 barrels (1390 tonnes)and 1000 barrels (139 tonnes) respectively. The fourth category is for spills in the range of 50 to 999bbl, and the fifth category is for spills in the 1 to 49 bbl category. In summary, the spill sizeclassifications used in this study are:

Exceptionally Large spills: >200,000 bbl (>27,800 tonnes)Extremely Large spills: >100,000 bbl (>13,900 tonnes)Very Large spills >10,000 bbl (>1390 tonnes)Large spills: >1000 bbl (>139 tonnes)Medium spills: 50 - 999 bbl (6.9 - 138.9 tonnes)Small spills: 1 - 49 bbl (0.14 - 6.89 tonnes)

Note that the top four categories are cumulative, for example, the large-spill category (>1000 bbl)includes the very large, extremely large and exceptionally large spills, and the very large categoryincludes extremely large spills, and so on.

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5.2 Exceptionally Large Crude Oil Spills

5.2.1 Historical Record

Exceptionally large spills, however familiar to the public, are unlikely events: there have only been53 such spills ever, as shown in Table 6. (The oil volumes are expressed in tonnes; multiply by 7.2for barrels.) the average size of the exceptionally large (>200,000 bbl) spills noted in the table is74,900 tonnes (539,000 barrels) and the median size is 53,000 tonnes (382,000 barrels).

No exceptionally large spill occurred before 1967 and only one occurred between 1981 and 1987.In 1988 two tanker total-losses occurred in the NW Atlantic, Odyssey and Athenian Venture, thelatter mentioned later in a Canadian context.

Over the past ten years the following nine exceptionally large spills (>200,000 bbl or >28,600tonnes) occurred. In March 1989 the Exxon Valdez went aground spilling some 250,000 barrels(35,000 tonnes) of crude oil in Prince William Sound, Alaska, and in late December 1989 the Kharg5 tanker spill happened off the coast of Morocco involving 540,000 bbl (72,000 tonnes). Noexceptionally large spills occurred in 1990, but in 1991 two major tanker spills happened off Italy:the Agip Abruzzo and the Haven. Also in 1991 the ABT Summer, carrying 260,000 tonnes of crudeoil, exploded and sank in the SE Atlantic, making it the second largest tanker oil "spill" in history;as with the Agip Abruzzo, much of the oil did not spill on water but rather either burned, or sank withthe tanker in 5-km deep water. Two exceptionally large spills occurred in 1992 (the Aegean Sea andthe Katina P.) and only two have occurred since, both off U.K. waters: the Braer (85,000 tonnes)off the Shetland Islands in 1993 and the Sea Empress (72,000 tonnes) off Wales in 1996. Insummary, an average of 1.6 exceptionally large spills (>200,000 bbl), many involving total losses,have occurred annually over the past 34 years since the Torrey Canyon spill in 1967. This hasreduced over the past ten years to one such spill per year. No exceptionally large spill has occurredsince 1996.

Nearly all the spills in Table 6 involved crude oil. It is known that 193.6 billion barrels of crude oilwere moved by tanker from the period 1974 to 1995 (Fearnley's World Bulk Trades Report–1999).The table shows that 35 exceptionally large spills occurred during this period. Therefore, thefrequency of exceptionally large tanker spills during this 22 year period was 35/(193.6 x 109)= 0.18spills per billion barrels transported. Based on recent experience in the 1980s and 1990s, thefrequency has dropped to about 0.1 spills per billion barrels of crude oil moved.

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Table 6. World's Largest Oil Spills from Tankers, 1942-1999

Rank Tanker Name Location Approximate Size (tonnes) Year1 Atlantic Empress Tobago 280,000 19792 ABT Summer SE Atlantic 260,000 19913 Castillo de Bellver Africa 260,000 19834 Amoco Cadiz France 230,000 19785 Haven Italy 140,000 19916 Odyssey NW Atlantic 130,000 19887 Torrey Canyon U.K. 120,000 19678 Sea Star Gulf of Oman 120,000 19729 Irenes Serenade Greece 120,000 1980

10 Urquiola Spain 110,000 197611 Texaco Denmark Belgium 100,000 197112 Hawaiian Patriot Pacific Ocean 99,000 197713 Independenta Turkey 93,000 197914 Julius Schindler Portugal 90,000 196915 Braer U.K. 85,000 199316 Jakob Maersk Portugal 80,000 197517 Kharg 5 Morroco 72,000 199618 Agip Abruzzo Italy 74,000 199119 Sea Empress U.K. 72,000 199620 Aegean Sea Spain 72,000 199221 Katina P. Mozambique 72,000 199222 Nova Arabian Gulf 72,000 198523 Wafra Africa 65,000 197124 Epic Colocotronis Puerto Rico 57,000 197525 Sinclair Petrolove Brazil 56,000 196026 Assimi Oman 53,000 198327 Metula Magellan Straits 53,000 197428 Andros Patria Spain 47,000 197829 World Glory S. Africa 45,000 196830 British Ambassador Japan 45,000 197531 Pericles GC Qatar 44,000 198332 Ennerdale Indian Ocean 43,000 197033 Tadotsu Strait of Malacca 42,000 197834 Mandoil II U.S. East Coast 40,000 196835 Napier Chile 36,000 197336 Trader Greece 35,000 197237 Texas Oklahoma NW Atlantic 35,000 197138 Irene’s Challenge Pacific 35,000 197739 St. Peter SE Pacific 35,000 197640 Juan A. Lavalleja Algeria 35,000 198041 Thanassis A. NW Pacific 35,000 199442 Exxon Valdez Alaska 35,000 198943 Burmah Agate Texas 34,000 197944 Athenian Venture NW Atlantic 32,000 198845 Golden Drake NW Atlantic 31,000 197046 Chryssi NW Atlantic 31,000 197047 Keo NW Atlantic 31,000 196948 Paceoan NW Pacific 31,000 196949 Caribbean Sea E. Pacific 31,000 197750 Grand Zenith NW Atlantic 31,000 197651 Cretan Star Indian Ocean 31,000 197652 Team Castor France 31,000 197953 Argo Merchant Cape Cod ( USA) 31,000 1976

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5.2.2 Exceptionally Large Crude Oil Spills in Canada

It is now important to ascertain whether the spill frequencies determined from worldwide statistics applyto Canadian waters. Since 1974, tankers have moved approximately 4 billion barrels of crude oil toCanada. Such tankers should have had 0.18 x 10-9 x 4 x 109 or 0.7 exceptionally large tanker spills since1974. If 50% of spills associated with Canadian-bound tankers occur on the outbound portion of thetanker's journey (in the Middle East, North Sea, Nigeria, etc.) and 50% on the inbound portion to Canada,then Canada had a 35% chance (0.5 x 0.7) of having such a spill over the past 25 years. Fortunately, thisdid not appear to happen. It is interesting to note, however, that the Athenian Venture tanker that brokeup and lost 230,000 barrels (32,000 tonnes) of crude oil in the northwest Atlantic off Canada in late 1988was on the inbound portion of its journey to Come-by-Chance, and could be considered a "Canadian"spill from a statistical viewpoint. Thus, in a sense, Canada has had at least one exceptionally large crudeoil spill in the past 25 years.

5.3 Extremely Large, Very Large and Large Crude Oil Spills

5.3.1 Historical Record

Because large, very large, and extremely large crude oil spills have been infrequent or non-existent inCanada, it is necessary to rely on worldwide statistics for these spill categories. It is known that about164.4 billion barrels of crude oil were transported on a worldwide basis from 1974 to 1992, as shown inTable 7. Table 7 also shows the number of extremely large (>100,000 bbl), very large (>10,000 bbl) andlarge crude oil spills (>1000 bbl) that have occurred during this 19-year period, both “in port”, meaningin harbours or at piers, and “at sea”, meaning away from ports either in restricted waters or in openwaters.

Using the statistics in Table 7 and other statistics, Anderson and LaBelle (1994) calculated oil spillfrequencies for the three different spill categories, and these are shown in Table 8 for the worldwidesituation. Note that both “average” and “median” size spill statistics are provided in Table 8. The averagesize spill is derived by simply dividing the total volume spilled by the total number of spills. The medianspill size in a given category means that 50% of the spills were smaller than the median size and 50%were larger. The average size is much larger than the median size because the former number is heavilyskewed by the handful of historical tanker spills of exceptionally large size.

Table 7. Number of worldwide crude oil tanker spills $$$$1000 bbl and crude oil movements, 1974-1992

Year

All

spills

Number of spills in port Number of spills at sea Crude oil

movements

(109 bbl)

Spills

per

109 bbl)1000-9999

bbl

10 000-99 999

bbl

100 000 bbl

and greater

1000-9999

bbl

10 000-99 999

bbl

100 000 bbl

and greater

1974 19 5 2 1 6 3 2 10.2 1.9

1975 19 2 0 3 5 7 2 9.3 2.0

1976 18 3 0 1 4 4 6 10.5 1.7

1977 15 1 2 1 3 3 5 10.7 1.4

1978 17 3 1 0 3 4 6 10.5 1.6

1979 22 3 2 2 4 5 6 11.0 2.0

1980 11 1 1 1 3 2 3 9.7 1.1

1981 7 3 1 0 3 0 0 8.5 0.8

1982 6 2 0 1 3 0 0 7.3 0.8

1983 13 4 1 0 1 4 3 6.9 1.9

1984 6 1 3 0 1 1 0 6.8 0.9

1985 5 1 2 0 1 0 1 6.4 0.8

1986 6 2 0 0 1 3 0 7.2 0.8

1987 11 3 1 0 4 3 0 6.8 1.6

1988 6 1 3 0 1 0 1 7.4 0.8

1989 12 3 0 0 1 5 3 8.0 1.5

1990 8 5 0 0 1 2 0 8.7 0.9

1991 6 0 0 1 2 1 2 9.2 0.7

1992 6 3 0 1 1 1 0 9.3 0.6

Total 213a 46 19 12 48 48 40 164.4 1.3

a 213 spills $1000 bbl totaling 22 191 00 bbl; includes 38 spills in U.S. waters totaling 1 868 800 bbl; excludes inland spills. Source: Anderson and LaBelle 1994

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Table 8. Worldwide Tanker Spill Rates, 1974-1992

Tanker spillsaNumberof spills

Averagespill size

(bbl)

Medianspill size

(bbl)Spill Rateb

(spills per 109 bbl)

$1000 bblIn PortAt SeaAll Spills

77136213

58 300130 100104 200

640022 00015 000

0.470.831.30

$10 000 bblIn PortAt SeaAll Spills

3188119

139 500198 700183 300

50 00088 40073 300

0.190.530.72

$100 000 bblIn PortAt SeaAll Spills

124052

310 300392 900373 800

251 000243 600243 600

0.070.240.31

a Crude oil spills only, excludes barge and inland spills (1 bbl = 0.159 m3).b Based on movement of 164.4 x 109 bbl crude oil.

Source: Anderson and LaBelle 1994

Table 9. Worldwide Tanker Spill Frequencies for Large Spills (>1000 bbl) in Port, RestrictedWaters (< 50 nm) and Open Sea (>50 nm), 1974-1992

Location Number ofspills

Average spillsize (bbl)

Spill rate (spills per 109

bbl)

In Port 77 58 300 0.47

Restricted Waters 110 122 000 0.67

Open Sea 26 198 000 0.16

All Locations 213 104 200 1.30

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For interest, spill rates for large and very large tanker spills in U.S. coastal and offshore waters are shownin Appendix B in Table B3. Similarly, the spill rates for tankers involved in North Slope crude oil tradeoperating out of Valdez, Alaska, are shown in Table B4. These tables show lower frequencies for boththese situations compared to the worldwide situation.

Note again the dramatic decrease in spill frequency when comparing spills in the 1970s to spills in the1980s and beyond.

It is now useful for later analysis to refine Table 8 in terms of the “at sea” statistics. In the late 1970s andearly 1980s MMS used to break the “at sea” statistics into the two categories of spills in “restrictedwaters,” defined by MMS as waters less than 50 nautical miles from land (93 kilometres) and spills inthe “open sea”, that is, beyond 50 nmiles of land. In these earlier studies it was shown that spills in theopen sea represented about 10% of the total number of large spills. This low percentage is understandablebecause most tanker spills occur during loading and unloading operations in port, or as a result ofcollision and grounding accidents, which mostly take place in harbours and restricted waters. Large tankerspills in the open sea are most likely to result from hull failures during poor weather, or fires andexplosions. Table 4 shows that spills resulting from such accidents represent about 13% of total spillswhere the cause is known.

In any case, it is of interest for later use to break down the “at-sea” statistics in Table 8 into the categoriesof “restricted waters” and “open sea”. The analysis is limited to “large” spills, that is, spills larger than1000 barrels. Table 8 shows that 136 such spills occurred “at sea” (restricted waters and open sea) duringthe time frame of 1974 to 1992. In Anderson and Lear (1994) spill locations are noted for all spills in thedatabase. The data show that of the 136 spills, 26 can be said to have occurred in the open sea, beyond50 nmiles of land. This represents 12% (26/213) of all large spills during the period. Table 9 summarizesthe reworked version of Table 8 including average spill sizes.

5.3.2 Large Crude Oil Spills in Canada

It is useful again to check the Canadian record against the worldwide one, this time with respect to largespills (>1000 bbl). Table 8 shows that the worldwide statistic for large tanker spills of crude oil is 1.3spills per billion barrels transported. Assuming as before that 4 billion barrels of crude oil have beenmoved by tankers to Canada since 1974, and assuming that 50% of spills associated with Canadian-bound

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tankers will occur on the outbound journey of the tanker and 50% in Canada, such tankers should havehad 1.3 x 10-9 x 0.5 x 4 x 109 or 2.6 large (>1000 bbl) tanker spills of crude oil during this period. Canadahas indeed suffered two large crude oil spills (>1000 barrels). One occurred in 1974 (the Imperial Sarniatanker spill off Brockville, Ontario) involving a discharge of 2100 barrels of oil, and the other occurredin 1988 (the Czantoria tanker spill in the port of Quebec) involving about 3300 barrels. There is also theexceptionally large Athenian Venture spill which occurred in the Northeast Atlantic far off Canada, butstill is a Canadian spill, statistically speaking.

5.4 Special Case of U.S. West Coast Crude Oil Traffic

About 25 million tonnes of crude oil per year move into ports in Puget Sound, Washington, mostly fromthe Port of Valdez, Alaska. This traffic comes very close to the south coast of Vancouver Island. Thefollowing is an attempt to estimate the likely occurrence of large spills from this traffic that could impactCanadian waters and coastlines.

Referring back to Table 9, it will be assumed that the at-sea component of risk for the Alaska-to-Washington traffic is negligible because tankers remain far offshore before approaching the Strait of Juande Fuca.. Similarly, it will be assumed that the "in port" component is not a risk to Canada. What remainsthen is the risk associated with the tankers sailing in restricted waters, meaning less than 50 nm from land.This risk is shared by the incoming and outgoing parts of the journey, namely the waters south ofVancouver Island as tankers approach and enter Puget Sound, and the restricted waters that tankers mustnegotiate on leaving Valdez after loading. Therefore, the estimated frequency of large (>1000 bbl) crudeoil spills from this traffic that represent a threat to Canada is simply 0.5 x 0.67 = 0.34 spills per billionbarrels transported.

The volume of oil moved is about 25 million tonnes per year or approximately 0.18 billion barrels peryear. The estimated annual spill rate of large spills (>1000 bbl) is then 0.18 x 0.34 = 0.061 spills per year.This is equivalent to one such spill every 16 years. This number will be brought forth in the final analysisof the report.

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5.5 Small and Medium Crude Oil Spills

Smaller spills occur much more frequently than do spills larger than 1000 barrels. Spill frequencies forsmall and medium size oil spills can be calculated by considering Canadian spill statistics which areavailable from NATES (the National Analysis of Trends in Emergencies System, maintained by theEnvironmental Emergency Program Division, Management and Emergencies Branch, EnvironmentCanada, Ottawa). The data in NATES for small and medium size spills of crude oil are shown in Table10. Crude oil spills larger than 1000 barrels are also shown for completeness.

The statistics in Tables 10 can be transformed into spill frequencies in terms of spills per billion barrelstransported by considering the oil volumes transported in Canada. The volume of crude oil traffic inCanada over the time period was about 22 million tonnes per year or about 0.165 billion barrels per year.This crude oil was generally imported to (the East Coast) or exported from (the West Coast) of Canadaby tanker; there were virtually no crude oil tanker shipments from a Canadian port to another Canadianport. The spill frequency results are shown in Table 11. These frequencies are associated with the entiretanker's journey, that is, both the inbound and outbound portions of a tanker's journey. In other word thespills noted in Table 10 are associated with only half of the tankers' voyages. Spills associated with theother half are presumed to take place outside Canada mostly in the foreign port areas that are at the otherend of the journey.

5.6 Spills from Tankers Carrying Petroleum Products other than Crude Oil

Analysing and predicting tanker spills of product oil is more difficult than doing so for crude oil. Thereare two problems. First, the international data base for product spills is not as good as that for crude oilspills. Second, much of the product oil movements in the world take place coastwise within countries.This traffic, mostly involving small vessels, is not often well recorded, and the amounts of oil moved inthis fashion are not easy to calculate.

For this reason we again use Canadian statistics from NATES (the National Analysis of Trends inEmergencies System, maintained by Environment Canada) to derive the necessary spill frequencies. Themajor problem with this, for very large spills, is that there have been only a couple of such spills inCanada, and it is questionable as to whether one can base a prediction on only two data points.

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Table 10. Spills of Crude Oil from Tankers in Canadian Waters (1973-1996)

Spill Size Range (bbl) Number of Spills Average Spill Size (bbl)

>1000 2 2560

50-999 6 233

1-49 31 10.4

Table 11. Crude Oil Tanker Spill Frequencies (per billion bbl transported) for Three Spill SizeRanges

Spill Size Range (bbl) Spills/Billion Barrels Transported

>1000 1.3 (from worldwide statistics)

50-999 3.0

1-49 15

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5.6.1 Large Product Oil Spills from Tankers

Table 12, derived from data available in NATES, lists all large product oil spills from tankers thatoccurred during the period 1973 to 1996. Note that no large spill has occurred since 1986.

The average size was 6200 barrels and the median spill size was 1600 barrels. The total number of spillsis 12, which equates to an annual spill frequency of 12/24 or 0.50 product oil spills (>1000 bbl) per year.This can be transformed into spill frequencies in terms of spills-per-billion-barrels-transported byconsidering the oil volumes transported during the period. The volume of product oil traffic in Canadaover the time period was about 0.20 billion barrels per year. This was all the oil loaded at Canadian portsplus all the oil unloaded. Consider that approximately 50 percent of the product oil over the period movedbetween Canadian ports and 50 percent was imported or exported (in 1998 the actual value was 55%).This means that 0.10 billion barrels were imported and unloaded at a Canadian port, or loaded at aCanadian port and exported, and 0.10 billion barrels were loaded and unloaded in domestic trade. Froma spill perspective only half of the import/export movements occurred in Canada waters (the other halfoccurred in the foreign waters), so only half of the spill risk for these spills occurred in Canada. For thedomestic shipments the volume of oil actually shipped or moved was one-half the volume reportedbecause it is counted once when loaded and once when unloaded, so the actual volume moved internallywas 0.05 billion barrels. Therefore, for statistical risk exposure purposes, the total volume moved was0.05 x 109 +0.05 x 109 = 0.10 x 109 barrels per year.

Having this number allows the calculation of the spill frequencies. The frequency of large (>1000 bbl)product oil spills in Canada has been:

(0.50 spills/yr)/[0.1 billion barrels/yr) = 5.0 spills per billion barrels moved.

Again, note that this frequency applies to the entire tanker's journey, i.e., both the inbound and theoutbound portions.

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Table 12. Accidental Spills of Product Oil Larger than 1000 bbl from Tankers in CanadianWaters (1973 -1996)

Tanker Name Spill Product Barrels Cause LocationYear Spilled Spilled

NTCL 1974 No. 2 Fuel Oil 1000 grounding Bushell Inlet, Sask.

Imperial St. Clair 1976 No. 2 Fuel Oil & Gasoline 1650 grounding Parry Sound, Ont.

Imperial Bedford 1977 No. 2 Fuel Oil 1360 equip. failure Charlottetown, PEI

Golden Eagle 1977 Nos. 4, 5 Fuel Oil 1430 equip. failure Marystown, Nfld.

???? 1977 No. 2 Fuel Oil 2790 intentional ???, BC

Canso Light 1979 No. 2 Fuel Oil 5880 grounding Canso Strait, N.S.

Kurdistan 1979 No. 6 Fuel Oil 49,900 material fail. Cabot Strait, N.S.

Imperial Acadia 1982 No. 2 Fuel Oil 1810 grounding Port aux Basque, Nfld.

Irving Eskimo 1983 No. 6 Fuel Oil 1580 grounding Sept Iles, Que.

Manolis L. 1985 Nos. 4, 5 Fuel Oil 3250 sinking Blow Hard Rock, Nfld.

Pointe Levy 1985 No. 6 Fuel Oil 1650 grounding Matane, Que.

Irving Wood 1986 Gasoline 1630 tank leak Miquelon Harbour, N.S.

Table 13. Spills of Petroleum Product from Tankers in Canadian Waters (1973 -1996)

Spill Size Number of Average SpillRange (bbl) Spills Size (bbl)

>1000 12 632050-999 58 2161-49 173 10.3

Table 14. Frequencies for Product Oil Tanker Spills in Canada, 1973 -1996

Spill Size Range (bbl) Spills/Billion Barrels Transported

>1000 5.050 to 999 24.61 to 49 72

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5.6.2 Very Large Product Oil Spills from Tankers

Because the average size of tanker carrying product oil in Canada is about 10,000 DWT we will assumethat the chances of an exceptionally large spill of product oil (> 27,800 tonnes) spill of product oil is verysmall or negligible. What remains is a an extremely large spill (> 13,900 tonnes) and a very large spill,defined as larger than 10,000 barrels or 1390 tonnes.

The two largest oil spills in Canadian history were the Arrow spill in 1970 (officially 108,000 barrels orabout 15,000 tonnes) and the Kurdistan spill in 1979 (about 7000 tonnes). This means that Canada hassuffered from one extremely large spill and two very large spills. (Remember that the very large spillrange also includes the extremely large spill range). This means that on average 1/30 = 0.033 extremelylarge spills/year have happened since 1970 and 0.067 very large spills. We will assume, as we did forthe case of exceptionally large spills, that the spill rate over the 1980s and 1990s has been approximately50% of the average of the past 20 to 30 years. This means the annual spill rates should be halved torepresent today's situation.

For calculation purposes we will make the same assumptions as we did in the previous section about theannual movement of product oil in Canada. The following equations then apply:

The frequency of extremely large (>100,000 bbl) product oil spills in Canada is:

(0.033/2 spills/yr)/[0.1 billion barrels/yr) = 0.167 spills per billion barrels moved.

And the frequency of very large (>10,000 bbl) product oil spills in Canada is:

(0.067/2 spills/yr)/[0.1 billion barrels/yr) = 0.330 spills per billion barrels moved.

Again, note that these frequencies apply to the entire journey of a tanker, i.e., both the inbound and theoutbound portions.

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5.6.2 Medium and Small Product Oil Spills

The data in NATES from medium spills (50 - 999 bbl) and small spills (1 - 49 bbl) are shown in Table13. Spills larger than 1000 barrels are also shown for completeness. These number can be transformedinto spill frequencies in terms of spills-per-billion-barrels-transported by using the same logic as beforefor the large spills. The results for all are summarized in Table 14.

5.7 Summary of Spill Frequencies

Here, all the spill frequency numbers generated above are summarized and converted to the units of"spills per billion tonnes loaded or unloaded" so they can be used directly with Tables 1 and 2 to calculateexpected spill rates (spills per year) for the specific port areas of Canada, for the CCG regions and forCanada as a whole. The results are shown in Table 15. Please note the following:

1. The spill frequencies shown in Tables 8 and 14 represent spills over an entire tanker's journey(including loading and unloading). Table 15 gives spill frequencies that be can be used directly withthe loading/unloading volumes from Statistics Canada reported here. These frequencies are half thenumbers shown in Tables 8 and 14. This is because oil loaded in one port in Canada that is unloadedin another is counted twice in Tables 1 and 2, once as a loading and once as an unloading.

2. Remember that frequencies for spills > 1000 barrels include the higher ranges. They are not additive.However, the lower three ranges (1- 49 bbl, 50 - 999 bbl and >1000 bbl) are additive, and the sumrepresents the frequency of all spills.

3. Product oil spill larger than 200,000 barrels are not possible, so the frequency was set at zero.Frequencies for the product oil categories of spills > 100,000 bbl and spills > 10,000 bbl are ofdubious value because they were calculated on the basis of one and two spills respectively.

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Table 15. Spill Frequencies (Inbound or Outbound Journeys) and Average and Mean Spill Sizes for Six Categories

Spill Category

Crude Oil Spills Product Oil Spills

Spill Frequencyb Spill Size Spill Frequencyb Spill Size

spills/ 109 bbl

loaded orunloaded

spills/109 T

loaded orunloaded

Average Median spills/ 109 bbl

loaded orunloaded

spills/109 T

loaded orunloaded

Average Median

ExceptionallyLarge, >200,000 bbl(>27,800 T)

0.050a 0.36 539,000 bbl

(74,900 T)

382,000 bbl

(53,000 T)

0 0 0 0

Extremely Large,>100,000 bbl(>13,900 T)

0.155 1.12 374,000 bbl

(51,900 T)

244,000 bbl

(33,800 T)

0.083 0.594 108,000bbl

(15,000 T)

108,000bbl

(15,000 T)

Very Large,>10,000 bbl (>1390T)

0.36 2.59 183,000 bbl

(25,5000 T)

73,300 bbl

(10,200 T)

0.167 1.20 79,000 bbl

(11,000 T)

79,000 bbl

(11,000 T)

Large, >1000 bbl(>139 T)

0.65 4.68 104,000 bbl

(14,500 T)

15,000 bbl

(2100 T)

2.5 18 6320 bbl

(878 T)

1688 bbl

(234 T)

Medium, 50-999bbl (6.9-138.9 T)

1.5 10.8 233 bbl

(32 T)

132 bbl

(18 T)

12.3 88.6 216 bbl

(30 T)

124 bbl

(17 T)

Small, 1-49 bbl(0.14-6.89 T)

7.8 56.2 10.4 bbl

(1.4 T)

5 bbl

(0.7 T)

36 260 10.3 bbl

(1.4 T)

5.8 bbl

(0.8 T)

a. Numbers are kept at three significant digits for calculation purposes.

b. These values are half the spill frequencies normalized by volumes moved because a movement includes a loading and an unloading.

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6.Calculation and Analysis of Regional Spill Rates

The frequency numbers in Table 15 are combined with the shipping statistics in Table 1 to producestatistics on the number of spills per year that are likely to happen in each CCG region for the sixcategories of spill size range. The results are shown in Table 16 (at the end of the section).

To obtain a breakdown of similar statistics for any specific port within the regions, simply multiply thefrequencies in Table 15 by the port volumes.

Not included in the table is the spill risk calculated earlier (in Section 5.4) for the movement of crude oilinto Puget Sound just south of Vancouver Island. The volume of oil moved is about 25 million tonnesper year. The estimated annual spill rate of large spills (>1000 bbl) was calculated to be 0.061 spills peryear. This is equivalent to one such spill every 16 years.

6.1 Relative Risk

The following conclusions can be made about the relative risk of oil spills across the country.

1. The Maritimes region by far has the greatest risk of spills. Literally half the total risk for the countryis in the Maritimes region. The risk picture is even worse than it seems from Table 16 because thetraffic to Quebec City poses as much a risk to the Maritimes Region as is does to the LaurentianRegion because tankers must transit the former region with the crude oil deliveries to Quebec. Asseen from Table 9, the risk of large spills in "restricted waters" is actually greater than the risk withinports, and the spill sizes are substantially larger. It is not surprising that the two largest oil spills inCanadian history, the Arrow spill in 1970 (about 15,000 tonnes) and the Kurdistan spill in 1979(about 7000 tonnes) occurred in this region.

2. The Newfoundland region would be ranked number two even though ports in the Laurentian Regionload and unload more oil. The reason is twofold. First, the volume of oil moved in the region isrelatively large and is growing quickly as the oil industry produces more Grand Bank oil and movesit by tanker to Whiffen Head through Placentia Bay. Second, much traffic to the Quebec and

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Maritime ports must pass relatively close to the coast of Newfoundland, and recent experiences withoiled birds washing ashore from illegal dumps from some this traffic show that the prevailingcurrents and winds can indeed push a large spill to the south coast of the province.

3. Quebec would be next for obvious reasons: a substantial amount of oil is moved in the province, thesecond largest amount in the country. The region is also troubled by having to deal with spills in theSt. Lawrence River. Spills in rivers are always more difficult to control than spills in low currentsituations, and spills in rivers can quickly be forced ashore by winds and oil can smear long stretchesof coast as the oil.

4. For the same reason the St. Clair River is Ontario is a hot spot because a substantial amount of oilis moved in the river to and from Sarnia (1.5 million tonnes loaded and unloaded in 1998), and theriver has very high currents, making spill control very difficult.

5. Finally, the Pacific region would have about the same risk of the Central region, and perhaps morebecause of the U.S. traffic to Puget Sound.

6.2 National Assessment

Remember that the spill rates for the larger crude oil spills in Table 16 were derived on the basis ofinternational statistics, and may not exactly apply to Canada, and that the spill rates predicted for the verylarge and extremely large product spills are based on only one or two spill events, and hence are ofdubious value. In any case, the table shows that the chance of a large spill (>1000 bbl) for the country asa whole is about one per year. This would not be a trivial spill inasmuch as its average and median spillsizes are estimated to be 14,500 tonnes and 2100 tonnes, respectively.

The spill of particular interest to the Coast Guard is likely to be the very large spill (>10,000 bbl) becausethis spill size range produces a median spill size of about 10,000 tonnes. This has been the size of interestfor planning purposes in Canada ever since the Brander-Smith panel exercise 10 years ago, and is closeto the spill size of the two largest spills already experienced by Canada. Table 16 shows that this spill sizehas a probability of occurrence of one in seven years.

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Table 16. Number of Spills per Year for Canadian Coast Guard Regions

Number of Spills per YearVolume Size Range Size Range Size Range Size Range Size Range Size Range

CCG Region (106 tonnes) 1 - 49 bbl 50 - 999 bbl > 1,000 bbl > 10,000 bbl > 100,000 bbl > 200,000 bblcrude 5.616E-02 1.080E-02 4.680E-03 2.592E-03 1.116E-03 3.600E-04

product 2.592E-01 8.856E-02 1.800E-02 1.20E-03 5.976E-04 0.00E+00

PacificCrude Oils 1.048 0.059 0.0113 0.0049 2.72E-03 1.17E-03 3.77E-04

Product Oils 2.649 0.687 0.2346 0.0477 3.19E-03 1.58E-03 0.00E+00Pacific Total 3.698 0.746 0.2460 0.0526 0.0059 0.0028 0.0004

Central (Arctic)Crude Oils 0.000 0.000 0.0000 0.0000 0.00E+00 0.00E+00 0.00E+00

Product Oils 0.480 0.124 0.0425 0.0022 5.77E-04 2.87E-04 0.00E+00Central (Arctic) Total 0.480 0.124 0.042 0.002 5.77E-04 2.87E-04 0.00E+00

Central (Ont)Crude Oils 0.004 0.000 0.0000 0.0000 1.09E-05 4.71E-06 1.52E-06

Product Oils 4.345 1.126 0.3848 0.0782 5.22E-03 2.60E-03 0.00E+00Central (Ont) Total 4.349 1.126 0.3848 0.0782 5.24E-03 2.60E-03 1.52E-06

LaurentianCrude Oils 7.181 0.403 0.0776 0.0336 1.86E-02 8.01E-03 2.88E-06

Product Oils 8.147 2.112 0.7215 0.1467 9.80E-03 4.87E-03 0.00E+00Laurentian Total 15.328 2.515 0.7991 0.1803 2.84E-02 1.29E-02 2.88E-06

MaritimesCrude Oils 23.975 1.346 0.2589 0.1122 6.21E-02 2.68E-02 8.63E-03

Product Oils 12.362 3.204 1.0948 0.2225 1.49E-02 7.39E-03 0.00E+00Maritimes Total 36.336 4.551 1.3537 0.3347 7.70E-02 3.41E-02 8.63E-03

NewfoundlandCrude Oils 7.170 0.403 0.0774 0.0336 1.86E-02 8.00E-03 2.58E-03

Product Oils 4.959 1.285 0.4392 0.0893 5.96E-03 2.96E-03 0.00E+00Newfoundland Total 12.129 1.688 0.5166 0.1228 2.455E-02 1.097E-02 2.581E-03

Total for Canada 72.320 10.750 3.343 0.771 0.142 0.064 0.01211 per year 3 per year one per year one in 7 years one in 16 years one in 86 years

<0 .5 Tonnes < 2 Tonnes 2100 Tonnes 10,200 Tonnes 33,800 Tonnes 53,000 TonnesMedian Spill Size

7. References

Anderson, C.M. and R.P. LaBelle. 1994. Comparative Occurrence Rates for Offshore Spills. SpillScience & Technology Bulletin, Vol. 1, No. 2, pp 131-141. Elsevier Sciences Ltd., Oxford, U.K.

Anderson, C.M. and E.M. Lear. 1994. MMS Worldwide Tanker Spill Database: An Overview. U.S.Department of the Interior, Minerals Management Service, Branch of Environmental Operationsand Analysis, OCS Report: MMS 94-0002.

CAC 1996. National Equipment Profile Study. Prepared by Consulting and Audit Canada (CAC) for theEnvironmental Response Program, Canadian Coast Guard, Project No. 570-1019, March 1996.

Card, J.C., P.V. Ponce and W.D. Snider. 1975. Tankship Accidents and Resulting Oil Outflows, 1969-1973. Proceedings of the 1975 Conference on the Prevention and Control of Oil Pollution, SanFrancisco, California, March 1975.

CCG 1991. 1991 Vessel Traffic Services (VTS) Update Study. Canadian Coast Guard, Ottawa, Ontario,December 1991.

ITOPF 1999. The International Tanker Owners Pollution Federation Limited Oil Spill DatabaseDownload from www.itopf.com

SL Ross. 1989. Expected Frequency of Spills from Tankers in or Near Canadian Waters. Prepared bySL Ross Environmental Research Ltd. for the Canadian Department of the Environment and theCanadian Coast Guard, August 1989.

SL Ross 1991. Estimation of Maximum Feasible Cleanup Capabilities for Large Tanker Spills inCanadian Nearshore Waters. the Canadian Petroleum Products Institute, January 1991.

USCG 1994. Oil Spill Risk Assessment Model and the Ranking of Ports for Oil Spill Vulnerability. U.S.Coast Guard R&D Center, Groton, Connecticut.

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