Executive Summary
One reason Congress enacted the Oil Pollution Act of 1990 (OPA 90) was to reduce the occurrence of oil spills through preventive measures and to reduce the impact of future oil spills through increased preparedness. Section 4115 of the act requires that tankers operating in U.S. waters must have double hulls. Tankers must comply with this double-hull requirement within a 25-year phase-in period. The secretary of transportation must establish regulations concerning single-hull tank vessels until they are retired. Some exceptions to the retirement schedule have been made for tank vessels that unload in offshore oil ports or use zones in the Gulf of Mexico designated for lightering (the transfer of loads to smaller vessels that can enter shallow ports).
Congress requested a report on the effects of the act on: (1) ship safety and protection of the marine environment, (2) the economic viability of the maritime transportation industry, and (3) the operational makeup of the industry. In 1994, the National Research Council (NRC) established the Committee on Oil Pollution Act of 1990 (Section 4115) Implementation Review, under the auspices of the Marine Board, to study these effects. The U.S. Coast Guard, acting on behalf of the U.S. Department of Transportation, asked the NRC to conduct a study and prepare a report for the U.S. Coast Guard to use in response to Congress. The committee determined that an assessment of the impact of double-hull requirements should also take into account the parallel hull design and ship operational requirements in the International Convention for the Prevention of Pollution from Ships (MARPOL), to which the United States adheres. In addition, the committee believes that understanding the technical changes in tank vessel design and operational experience is important in developing a complete assessment of the effects of OPA 90 (Section 4115) on the safety and protection of the marine environment.
The committee is conducting this study in two phases. This interim report, completed during the first phase, reviews the availability and adequacy of the data and information needed to assess the effects of OPA 90, as requested. In the second phase of the study, the committee will assess the data and draw conclusions, which will be summarized in a final report to be issued in early 1997.
The following are the committee's findings regarding the availability and adequacy of data.
Ship safety and protection of the marine environment. Sufficient data are available to ascertain the number and volume of oil spills prior to and after the enactment of OPA 90. However, some governments and operators have taken action to enhance ship safety and environmental protection that complicate the effort to determine the effects of Section 4115 of OPA 90. In addition, mandated changes in vessel construction and operation are only now coming into effect, and interim measures for existing single-hull tank vessels have not yet been promulgated domestically.
Economic viability of the industry. The data required to assess the economic effects of OPA 90 and MARPOL are readily available. Although the data should be adequate for making an assessment, comparing various data sources and determining maintenance costs could be difficult. Data are available to support committee estimates of world capacity for constructing new tankers in relation to projected demands. The committee will review these capacity data and compare recent delivery levels to the demand for new tankers.
Operational makeup of the industry. The data are generally adequate for assessing changes in the operational makeup of the maritime oil transportation industry. Information on larger tanker operations (ships weighing more than 30,000 deadweight tons) are particularly complete and available. One area of uncertainty is likely to be evaluating changes in and forecasts of shipping patterns, including the effects of offshore terminals and lightering.
Changes in tank vessel design, maintenance, and ship operations. Extensive studies and model tests to determine the effects of grounding and collisions of double-hull tankers have been underway at universities and government facilities in the United States and abroad. The committee will continue to review new double-hull designs and test results and to evaluate improvements in design, construction, and maintenance to increase ship safety and reduce oil outflow after an accident. The committee believes sufficient information will be available to assess progress in double-hull vessel design since 1990. This information, along with operational experience gained from the long service of a small number of double-hull vessels and from new double-hull tankers, will be analyzed for implications for improved safety.
