Following the grounding of the Exxon Valdez in Prince William Sound in March 1989, which resulted in the loss of more than 11 million gallons of crude oil into Alaskan waters, the U.S. Congress promulgated P.L. 101-380, the Oil Pollution Act of 1990 (OPA 90). The intent of this law was to minimise oil spills through a variety of mechanisms, including improved tanker design, changes in operations, and other actions aimed at improving the capability to manage the cleanup of oil spills should they occur. Section 4115 of OPA 90 mandated changes in ship design and construction to prevent or minimise spillage in accidents, establishing the double-hull standard for tankers that transport oil in U.S. waters and call on U.S. ports. Following the passage of OPA 90, changes in the international regulatory regime in the form of two additions to MARPOL 73/78 mandated a world-wide transition to double-hull vessels or their equivalent. Since 1990, then, the world tanker fleet has been changing to double-hull construction. During the same time, however, number of alternative tanker designs have been proposed with the intent of providing performance equivalent to or better than double hulls. While both OPA 90 and MARPOL regulations allow for the possibility of accepting alternative designs, provided they are equivalent to or better than double hulls in limiting oil outflow in case of a contact accident, the United States Coast Guard (USCG) has not accepted any other design as equivalent. IMO, on the other hand, has adopted two alternative designs as equivalent to the double hull. To date, no alternative designs have actually been built. The Coast Guard Authorisation Act of 1998 mandated the Secretary of Transportation to commission the Marine Board of the National Research Council’s (NRC) Transportation Research Board (TRB) to develop a rationally based approach and method for assessing the environmental performance of alternative tanker designs relative to the double-hull standard. (A copy of the relevant legislation is found in Appendix B.) Under the auspices of the Marine Board, NRC convened an 11-member Committee for Evaluating Double-Hull Tanker Design Alternatives with appropriate scientific and technical expertise in risk assessment, tanker design, tanker operations, crashworthiness of ships, and costs and damages (including environmental damages) related to oil spills. Committee members had extensive experience in the day-to-day operations of all relevant technologies, as well as in the overall analysis of operations and risks and in systems management (see Study Committee Biographical Information at the end of this report). The committee as a whole met five times between June 1999 and January 2001, and subgroups met periodically throughout that period. The early meetings included extensive presentations in sessions open to the public, during which experts from government, academia, and industry described a variety of issues and views for the committee. (See Appendix A for a listing of the presentations provided.) This final report represents a synthesis of the information gathered by the committee, which encompassed the data, analytical tools, and simulation methods currently available for the development of a rationally based approach for assessing the environmental performance of alternative tanker designs relative to the double-hull standard. (Author/publisher)
Samenvatting