National Academies Press: OpenBook

Oil Spill Risks From Tank Vessel Lightering (1998)

Chapter: 5 Conclusions and Recommendations

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Suggested Citation:"5 Conclusions and Recommendations." National Research Council. 1998. Oil Spill Risks From Tank Vessel Lightering. Washington, DC: The National Academies Press. doi: 10.17226/6312.
×

5
Conclusions and Recommendations

Current lightering operations, which are conducted in a variety of locations in the United States using a variety of methods, are safe. The best available data on marine casualties and oil spills demonstrate that very few vessel accidents or spills in U.S. waters can be directly attributed to lightering operations. The safety record of lightering in recent years has been excellent. This observation is generally supported by representatives of oil, shipping, and lightering companies, as well as by government regulatory officials and members of environmental groups and the general public.

Lightering is an effective and efficient method of supplying U.S. refineries and storage facilities with foreign crude oil and petroleum products. The practice is less expensive than transporting oil by small tankers, minimizes deep-ocean traffic, and eliminates the need for very large oil tankers to enter U.S. ports. These advantages, combined with the good safety record of lightering, support the continued use of lightering.

The good safety record notwithstanding, the risk of spills from lightering could be reduced even further. The majority of the committee's recommendations are intended for industry. The rest are for the USCG and other federal agencies.

Recommendations for Shipping Companies and Organizations

Industry Guidelines for Inshore Lightering

The OCIMF Ship to Ship Transfer Guide provides vessel operators with minimum standards for safe offshore lightering operations. The guidelines were

Suggested Citation:"5 Conclusions and Recommendations." National Research Council. 1998. Oil Spill Risks From Tank Vessel Lightering. Washington, DC: The National Academies Press. doi: 10.17226/6312.
×

developed through a cooperative effort of the organization's international membership. Although the safety record of inshore lightering is excellent, the committee could not find universal guidelines defining minimum standards for inshore lightering. Many OCIMF guidelines can be readily applied to inshore operations, but this segment of the industry has a number of unique characteristics, such as the extensive use of barges and the frequent transport of specialized refined products, that may require the development of new standards. The committee, therefore, concludes that the industry would be well served by the development of standards and guidelines specifically for inshore lightering.

Recommendation 1. Industry organizations, such as the American Waterways Operators or cooperative organizations modeled on the Industry Taskforce on Offshore Lightering should develop standards and guidelines for inshore lightering operations. This document could either supplement or incorporate appropriate sections of the Oil Companies International Marine Forum guidelines for offshore operations.

Adherence to OCIMF guidelines

Judging from the data on lightering spills since the 1980s and the committee's site visits and review of the literature, lightering is a safe process that has a very low spill rate and manageable risks. Furthermore, the safety record of lightering is likely to stay the same or even improve as the overall quality in the shipping industry improves as a result of OPA 90, STCW, and ISM and as industry standards and practices for lightering specifically (such as the guidelines developed by OCIMF and ITOL) continue to evolve. However, anecdotal evidence and the experience and observations of committee members indicate that OCIMF guidelines are not applied uniformly throughout the shipping industry. Therefore, the committee concludes that, even though additional government regulations are not warranted, the industry should encourage all operators to adhere to best operational and management practices.

Recommendation 2. Chartering organizations should screen all prospective ships to be lightered to determine whether they meet Oil Companies International Marine Forum standards for vessels, equipment, and crews and should not charter vessels that do not meet these standards. As a supplementary measure to determine whether this self-policing process is effective, the U.S. Coast Guard should monitor the process and call for periodic reports when appropriate and needed.

Information on Vessel Conditions

The SIRE system is an oil industry initiative that facilitates the sharing of data among OCIMF members on vessel conditions. The data are used to make decisions about vessel chartering. The information in the SIRE database could also help

Suggested Citation:"5 Conclusions and Recommendations." National Research Council. 1998. Oil Spill Risks From Tank Vessel Lightering. Washington, DC: The National Academies Press. doi: 10.17226/6312.
×

lightering companies decide which vessels to charter and make plans to accommodate nonstandard features on particular vessels. Indeed, this information could help lightering companies deal with one of the major variables in lightering—the condition of STBLs. However, under current SIRE regulations, the OCIMF is not in a position to release vessel information to lightering companies. The committee concludes that the safety of lightering operations might be enhanced if lightering companies had access to the information in the SIRE system.

Recommendation 3. The Oil Companies International Marine Forum should consider making limited revisions to its Ship Inspection Report regulations to give lightering companies access to information on the condition of vessels.

Vessel Design, Construction, and Operation

The safety of lightering operations depends heavily on the compatibility of the two vessels involved and design features that support appropriate equipment. At a minimum, vessels must be designed and constructed to accommodate effective primary and secondary fenders and a strong, well balanced, flexible mooring system. Vessels must also be capable of maneuvering at low speeds for extended periods of time. A wide range of vessel designs, some more appropriate than others, are currently used for lightering vessels. Some attention has been paid to design issues of particular importance to lightering (e.g., the IMO guidelines for safe loading and unloading of single-tank-across double-hull vessels), and this positive trend should be continued. The committee concludes that attention should continue to be focused on vessel design, construction, and operation to support ship-to-ship transfer operations, particularly with respect to vessels that are likely to be used for lightering at some point in time. Issues that should be emphasized include the extent of vertical plating and parallel bodies on vessels, the size and placement of mounting points and lifting equipment, engine capabilities, and the potential for excessive freeboard.

Recommendation 4. To promote the adequate rigging of secondary fenders, the Oil Companies International Marine Forum should emphasize (e.g., in the next edition of its lightering guidelines) the need for vertical and flat surfaces as high as possible along vessel sides above the load waterline, with the maximum amount of vertical sides consistent with design requirements. In addition, mounting points, leads, and lifting equipment for secondary fenders should be positioned and sized for optimum effectiveness, and leads and securing facilities should be provided for primary fenders to ensure maximum coverage.

Recommendation 5. The Oil Companies International Marine Forum should focus on the need for vessels to have enough full-sized mooring bitts and enclosed chocks to secure the two vessels together a minimum of four lines forward and aft. A minimum of one full-sized mooring bitt and enclosed chock should be

Suggested Citation:"5 Conclusions and Recommendations." National Research Council. 1998. Oil Spill Risks From Tank Vessel Lightering. Washington, DC: The National Academies Press. doi: 10.17226/6312.
×

provided within 35 meters forward and aft of the manifold. All mooring lines should be secured by winches.

Recommendation 6. The Oil Companies International Marine Forum should focus on the need for vessels that are capable of slow steaming for extended periods of time (within the limited operating range of modern diesel engines) with fine control of engine revolutions to enable safe maneuvering during mooring and unmooring operations.

Recommendation 7. The Oil Companies International Marine Forum should recommend limited operating parameters for modern double-hull tankers used as ships to be lightered to accommodate excessive freeboard (up to about 85 feet) when the cargo tanks are empty, a condition that can degrade the integrity of the mooring between the ship to be lightered and the service vessel. At the same time, the International Maritime Organization should consider modifying MARPOL, Annex I, Regulation 13, or classifying lightering as an "exceptional case," to permit greater ballasting when transferring oil to a service vessel.

Lightering Equipment

A wide range of equipment is available for lightering purposes, and the specifications and arrangements outlined in the OCIMF guidelines are adequate. However, the observations and experience of committee members suggests that certain types of equipment are better for lightering operations than others. The shock-absorption capability of mooring lines is enhanced if the lines are fitted with synthetic tails. The use of truck tires instead of fenders, a practice that has been observed in some locations in the past, is questionable from a safety standpoint. Existing standards and guidelines for inspecting and testing hoses, especially the USCG's maximum allowable working pressure (as opposed to the OCIMF's "rated pressure") should be used as a baseline for testing hoses. The committee concludes that industry guidelines on the specifications and handling of equipment generally provide adequate margins of safety for lightering operations, but safety could still be improved.

Recommendation 8. Mooring lines should be fitted with synthetic tails and fenders designed specifically for lightering operations. Lightering operators should also adhere carefully to existing standards and guidelines with regard to the inspection and testing of hoses.

Communications

The safety of lightering depends heavily on effective communications between the STBL and the service vessel, as well as among the officers and crew members on each vessel. Difficulties sometimes arise because one or more key individuals on the STBL (which are usually foreign-flag vessels and often have crews of mixed

Suggested Citation:"5 Conclusions and Recommendations." National Research Council. 1998. Oil Spill Risks From Tank Vessel Lightering. Washington, DC: The National Academies Press. doi: 10.17226/6312.
×

nationalities) are not fluent in English. The committee, therefore, concludes that measures should be taken to ensure that key individuals are fluent in English.

Recommendation 9. Before initiating cargo transfer operations, the mooring master (or equivalent person in charge) aboard the service vessel should determine whether the key individuals on the ship to be lightered are fluent in English and can understand the lightering plans and respond to commands. If necessary, an individual (reporting to the lightering master or other official in charge of lightering) who is both fluent in English and knowledgeable about lightering should be put aboard the ship to be lightered prior to the transfer of cargo.

Cargo Gauging

After a lightering operation is completed, the cargo inspectors gauge the oil in the tanks of both vessels to determine the amount discharged and received. This gauging process can take more than two hours, and the measurements are often only approximate because the service vessel is moving in the seaway. In marginal, adverse, or worsening weather, the mooring master is anxious to separate the vessels. The cargo gauging process is repeated when the service vessel reaches port, and this figure is more accurate because the vessel is steady in port. The committee, therefore, concludes that cargo gauging offshore is redundant and, in marginal or adverse weather, constitutes an unnecessary risk, at least in U.S. waters.

Recommendation 10. To limit the time that vessels are alongside each other in a seaway and avoid delays in departure under adverse or marginal weather conditions, the Industry Taskforce on Offshore Lightering should suggest (e.g., in the next edition of its offshore lightering guidelines) that the mooring master and vessel master dispense with the inspector's gauging (at least on the service vessel) until the vessel is in port. If cargo quantities must be ascertained offshore, gauging should be limited to the ship to be lightered and should be done after the service vessel has departed. The cargo measurements for the service vessel could be telexed to the ship to be lightered.

Recommendations for the U.S. Coast Guard and Other Federal Agencies

Cooperative Problem Solving

ITOL is a cooperative organization, established at the suggestion of the USCG, that promotes self-policing in the industry and, in partnership with the USCG, promotes continuous improvement in the lightering process in the Gulf of Mexico. Among its accomplishments, ITOL has published the Industry Lightering Operations Supplement to OCIMF Ship to Ship Transfer Guide, which was approved by the USCG in 1990. In addition, ITOL has worked with the

Suggested Citation:"5 Conclusions and Recommendations." National Research Council. 1998. Oil Spill Risks From Tank Vessel Lightering. Washington, DC: The National Academies Press. doi: 10.17226/6312.
×

USCG to develop the regulations for designated lightering zones and to write pollution-response guidelines for the industry. ITOL has also obtained pre-approval for the use of oil dispersants in traditional lightering areas.

The effectiveness of ITOL is reflected in the low incidence of oil spills in relation to the quantity of cargo transferred in the Gulf of Mexico. The committee concludes that the organization is an excellent example of how industry and government cooperation can reduce the risks associated with oil spills.

Recommendation 11. The U.S. Coast Guard should encourage the lightering industry on the east and west coasts to adopt or adapt the Industry Taskforce on Offshore Lightering model as part of their program to promote problem solving, interaction, and cooperation to enhance safety and environmental protection. Cooperative arrangements could be initiated through existing mechanisms, such as the American Waterways Operators/U.S. Coast Guard Safety Partnership.

Weather Forecasting

Accurate, timely weather forecasts are essential to safe lightering operations. Forecasts are necessary for operations in designated lightering zones and traditional lightering areas on all three U.S. coasts. The committee found a number of problems with respect to the availability and usefulness of marine weather forecasts for lightering purposes. Reported problems include the inappropriate location of weather buoys, a lack of real-time information, and delays in repairs to weather buoys. The committee concludes that the safety of lightering operations would be enhanced if weather information was more reliable and accessible.

Recommendation 12. The U.S. Coast Guard, in consultation with the lightering industry, should work with the National Weather Service and the U.S. Navy to select appropriate locations for weather buoys and to tailor weather data and forecasts to support operations in both designated lightering zones and traditional lightering areas. The National Weather Service should take on this task as a priority to improve the delivery of weather information to enhance safety in offshore operations.

Waivers for Departures from Designated Lightering Zones

Vessels that must use designated lightering zones are barred by law from departing from these zones during lightering operations, except in emergency situations when waivers are granted by the local COTP. The shipping industry has attempted to modify this restriction, arguing that unforeseen circumstances sometimes extend the duration of a lightering operation to the point that the vessels approach the zone boundary while they are still moored together and under way. To avoid crossing the boundary, the vessels must either be maneuvered while they are moored together or separated prior to completing a lift. Either

Suggested Citation:"5 Conclusions and Recommendations." National Research Council. 1998. Oil Spill Risks From Tank Vessel Lightering. Washington, DC: The National Academies Press. doi: 10.17226/6312.
×

option poses safety risks. The committee concludes that this maneuvering or separation could unnecessarily increase the risk of spills.

Recommendation 13. The U.S. Coast Guard captain of the port should be given the authority, based on a case-by-case review of individual requests and circumstances, to allow vessels to leave designated lightering zones for safety reasons while still engaged in lightering.

Collection of Data on Spills

An immense amount of information is available on maritime accidents from the USCG databases, state agencies, and private sources. However, it is extremely difficult to sort through this information to gather reliable data on the history of oil spills related to lightering in U.S. waters. The difficulties include inconsistent reporting and ambiguous information on the underlying causes of accidents. To create a national picture of the lightering-related spill pattern, accident data of varying degrees of detail and reliability must be combined from various sources. The committee gathered sufficient anecdotal and experiential evidence to verify the very low rate of lightering-related spills, but the process was laborious. The committee, therefore, concludes that the analysis—and presumably the prevention—of accidents would be enhanced by the development of an accurate, comprehensive database on maritime oil spills that would enable users to sort all spills in U.S. waters by the causes of accidents, including equipment failure modes, the activities (e.g., lightering) under way at the time, and other pertinent variables.

Recommendation 14. The U.S. Coast Guard should develop, or hire a private contractor to develop, an accurate, comprehensive computer database on maritime oil spills that can be searched and sorted by pertinent variables, including the causes of accidents.

Human Error

Human error is a factor in a large percentage of maritime casualties, including the few lightering-related spills. Although human factors is an important issue in improving maritime safety, many other studies, as well as existing and emerging standards and regulations, are already addressing this subject. Moreover, problems in this area are not unique to lightering. The committee concludes, therefore, that human factors in maritime safety are likely to be addressed adequately in other studies and in the development of improved standards and practices in the maritime industry in general and do not require special attention with respect to lightering. However, lightering companies and operators should continue to be involved with industry improvements.

Suggested Citation:"5 Conclusions and Recommendations." National Research Council. 1998. Oil Spill Risks From Tank Vessel Lightering. Washington, DC: The National Academies Press. doi: 10.17226/6312.
×

Charting Pipelines

Vessels engaged in lightering in the Gulf of Mexico may have to anchor, either while awaiting the arrival of a service vessel or during the cargo transfer process. Anchors can weigh as much as 29 tons—more than enough to damage, and cause a spill from, one of the growing number of oil pipelines on the ocean bottom. To avoid damaging pipelines and causing spills, the operators of STBLs and service vessels need accurate data on the location of underwater pipelines in designated lightering zones and traditional lightering areas. Federal agencies do not currently collect and publish these data on a regular basis. A recent private survey highlighted the need for this data. The survey revealed that the bottom in one designated lightering zone is covered by pipelines. The committee concludes that there is an urgent need for the regular collection of accurate data on the locations of pipelines in the Gulf of Mexico, especially in designated lightering zones and traditional lightering areas.

Recommendation 15. The Minerals Management Service (of the U.S. Department of the Interior) and the Office of Pipeline Safety (of the U.S. Department of Transportation) should develop and implement a plan to collect and compile accurate data on the location of pipelines in the Gulf of Mexico and make the information available to the operators of vessels that engage in lightering. Priority should be placed on data collection in designated lightering zones and traditional lightering areas, and the data should be verified and updated on a regular basis.

Recommendation 16. To ensure safe anchorages amid the increasing oil and gas exploration activity, the U.S. Coast Guard should seek authority to designate ''pipeline-free areas'' where new pipelines cannot be laid.

Suggested Citation:"5 Conclusions and Recommendations." National Research Council. 1998. Oil Spill Risks From Tank Vessel Lightering. Washington, DC: The National Academies Press. doi: 10.17226/6312.
×
Page 87
Suggested Citation:"5 Conclusions and Recommendations." National Research Council. 1998. Oil Spill Risks From Tank Vessel Lightering. Washington, DC: The National Academies Press. doi: 10.17226/6312.
×
Page 88
Suggested Citation:"5 Conclusions and Recommendations." National Research Council. 1998. Oil Spill Risks From Tank Vessel Lightering. Washington, DC: The National Academies Press. doi: 10.17226/6312.
×
Page 89
Suggested Citation:"5 Conclusions and Recommendations." National Research Council. 1998. Oil Spill Risks From Tank Vessel Lightering. Washington, DC: The National Academies Press. doi: 10.17226/6312.
×
Page 90
Suggested Citation:"5 Conclusions and Recommendations." National Research Council. 1998. Oil Spill Risks From Tank Vessel Lightering. Washington, DC: The National Academies Press. doi: 10.17226/6312.
×
Page 91
Suggested Citation:"5 Conclusions and Recommendations." National Research Council. 1998. Oil Spill Risks From Tank Vessel Lightering. Washington, DC: The National Academies Press. doi: 10.17226/6312.
×
Page 92
Suggested Citation:"5 Conclusions and Recommendations." National Research Council. 1998. Oil Spill Risks From Tank Vessel Lightering. Washington, DC: The National Academies Press. doi: 10.17226/6312.
×
Page 93
Suggested Citation:"5 Conclusions and Recommendations." National Research Council. 1998. Oil Spill Risks From Tank Vessel Lightering. Washington, DC: The National Academies Press. doi: 10.17226/6312.
×
Page 94
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The safety record of lightering (the transfer of petroleum cargo at sea from a large tanker to smaller ones) has been excellent in U.S. waters in recent years, as evidenced by the very low rate of spillage of oil both in absolute terms and compared with all other tanker-related accidental spills. The lightering safety record is likely to be maintained or even improved in the future as overall quality improvements in the shipping industry are implemented. Risks can be reduced even further through measures that enhance sound lightering standards and practices, support cooperative industry efforts to maintain safety, and increase the availability of essential information to shipping companies and mariners. Only continued vigilance and attention to safety initiatives can avert serious accidents involving tankers carrying large volumes of oil.

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