TABLE D-4 Summary of Offshore Pipeline Spill Data for North American Waters, 1990-1999

Annual Oil Spillage From Offshore Pipelines in US Waters (1990-1999)

Year

Number Spills (>100 gal)

Tonnes Spilled

Gallons Spilled

Avg. Spill Size (Tonnes)

Avg. Spill Size (Gallons)

1990

9

2,621.15

779,882

291

86,654

1991

19

22.89

6,300

1

332

1992

9

319.97

86,730

36

9,637

1993

7

13.72

3,780

2

540

1994

2

599.74

190,684

300

95,342

1995

4

4.96

1,344

1

336

1996

4

25.65

6,952

6

1,738

1997

8

6.11

1,693

1

212

1998

6

1,559.60

430,214

260

71,702

1999

7

500.34

135,611

71

19,373

Total

75

5674.13

1,643,190

97

28,587

 

SOURCE: Minerals Management Service; Analysis by Environmental Research Consulting

outs is even harder to estimate as data is even more difficult to acquire. As of 1993, there were 3,182 additional offshore oil and gas facilities located in non-North American waters (International Association of Oil and Gas Producers, 2000). If it assumed that the average amount of petroleum hydrocarbons spilled by these platforms was similar to those found in North American waters, the estimated additional average spill volume would be 115.0 tonnes per year (0.036 tonnes per platform per year). Comparison of this calculation with scattered data from the North Sea and offshore Africa tended to indicate that the computed figure was extremely low. Using the data cited above, an average of 0.045 tonnes per platform (reflecting a 25 percent increase in the per platform release rate1) was used to compute the volume discharged into the sea by non-North American platforms. The resulting computed value is 144.0 tonnes per year. It is the opinion of the committee that this number is still low, but until more systematic data is collected worldwide on discharges from platforms, a more precise volume is lacking. Thus, on an annual basis, an estimated 290.0 tonnes are spilled into the world’s oceans by all offshore oil and gas platforms (Table D-3).

DeLuca and LeBlanc (1997) estimate that there are 59,512 miles of offshore oil and gas pipelines in the major oil producing countries of the world (North America not included). Again, this number is probably too low by as much as 30%, but these are the only published figures available. If it is assumed that the average amount of petroleum hydrocarbons discharged per mile of pipeline in North America is (0.074 tonnes per year per pipeline mile), then an additional 4,410 tonnes are discharged into the other world’s oceans by non-North American pipelines. Thus, on an annual basis,

TABLE D-5 Summary of Pipeline Spill Data in North American Coastal Waters, 1990-1999

 

 

Tonnes

U.S. Gallons

Year

No. Spills

Total

Ave./Spill

Total

Ave./Spill

1990

25

2,919.99

116.80

791,317

31,653

1991

5

1,095.85

219.17

296,975

59,395

1992

22

1,010.06

45.91

273,726

12,442

1993

11

1,438.91

130.81

389,945

35,450

1994

22

11,344.55

515.66

3,074,373

139,744

1995

13

53.97

4.15

14,626

1,125

1996

19

3,670.65

193.19

994,746

52,355

1997

10

1,401.77

140.18

379,880

37,988

1998-1999

17

530.14

31.18

143,668

8,451

Total

144

23,465.89

 

6,359,256

 

Ave./Year

16

2,607.32

 

706,584

 

1  

Assuming that non-North American platforms release 25 percent more petroleum per year is a somewhat subjective figure, but reflects the lack of worldwide standards. In other words, while some regions set standards as high as North American producers operate under, these standards are not uniformly applied worldwide. Thus, the adjustment is conservative in that it reflects the assumption that less regulated operations are more prone to release petroleum.



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