TABLE E-14 Total Bilge Oil Discharge—North American Waters (for vessels greater than or equal to 100 GT)

 

(tonnes)

(gallons)

United States

81

 

Canada

11

 

Mexico

7

 

Best estimate

99

26,465

bilge oil amongst the various zones. These results are summarized in Table E-15.

Summary of Fuel Oil and Bilge Oil Inputs (for Vessels greater than or equal to 100 GT)

Estimated operational discharges for both North American waters and international waters are summarized in Tables 2-2 through 2-6. Considering the high level of uncertainty in the assumptions on the extent of MARPOL compliance, the minimum estimate is taken as 50% of the best estimate, and the maximum estimate at twice the best estimate.

Fuel Oil and Bilge Oil Inputs in North American Waters (for Vessels less than 100 GT)

Bilge oil discharges into U.S. marine waters for vessels less than 100 GT in size are summarized in Table E-16. According to U.S. Coast Guard Marine Safety Management System (MSMS) database, in year 2000 there were 41,313 registered vessels in the U.S. under 100 GT, other than tankers, cargo ships, and recreational vessels. This average size for propulsion machinery was 350 HP. It was assumed that these vessels generated 0.09 gallons of bilge oil per day, operated 50 days per year, and that 60% of the vessels operated in marine (non inland) waters. These estimates were the best judgment of the committee, as data were not available. Based on the above, the total bilge oil generation in the vessels less than 100 GT was calculated to be 385 tonnes per year (108 thousand gallons per year).

A 70% compliance level was assumed for these smaller vessels. For MARPOL compliant vessels, it is assumed that all bilge oil is retained onboard and disposed at suitable reception facilities. For non-compliant vessels, 100% discharge of bilge oil is assumed. The calculated value, also considered the best estimated, was therefore 30% of 385 tonnes per year, or 115 tonnes per year (33 thousand gallons per year). All of these discharges are assumed to be diesel oil and other light distillates. The distributions by zone are summarized in Table E-18. Due to the very high level of uncertainty in these calculations, a range from 23 tonnes per year (20% of the best estimate) to 575 tonnes per year (five times the best estimate) was selected. Worldwide estimates for vessels under 100 GT were not developed due to the lack of data. Also, estimates were not developed for Canadian and Mexican waters.

Accidental Spills from Vessels in North American Waters
Spill Trends in U.S. Waters

Figure E-1 shows the oil spillage in U.S. waters from tank vessels during the period from 1973 to 1999. The oil spill data are from the Environmental Research Consulting Spill

TABLE E-15 Operational Discharge Summary (for vessels greater than or equal to 100 GT)

 

Best Estimate (tonnes)

Minimum (tonnes)

Minimum (tonnes)

Best Estimate (gallons)

Maximum (gallons)

Maximum (gallons)

North American Waters

Machinery Space Bilges

99

 

 

26,465

 

 

Fuel Oil Sludge

0

 

 

0

 

 

Oily Ballast From Fuel Tanks

0

 

 

0

 

 

Total—North American Waters

99

33

300

26,000

9,000

80,000

International Waters

Machinery Space Bilges

16,637

 

 

0

 

 

Fuel Oil Sludge

255,700

 

 

0

 

 

Oily Ballast From Fuel Tanks

0

 

 

0

 

 

Total—International Waters

270,000

90,000

810,000

70,000,000

23,000,000

210,000,000

Worldwide

Machinery Space Bilges

16,736

 

 

4,322,783

 

 

Fuel Oil Sludge

255,700

 

 

65,459,110

 

 

Oily Ballast From Fuel Tanks

0

0

 

 

 

 

TOTAL—WORLDWIDE

270,000

90,000

810,000

70,000,000

23,000,000

210,000,000

NOTE: All totals rounded to two significant figures.



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement