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OCR for page 141
7 CONCLUSIONS AND RECOMMENDATIONS 1. Of the estimated 56,600 metric tons of hydrocarbon vapor emis- sions from tank vessels in 1985 (about 0.2 percent of national volatile organic compound emissions), about 95 percent, came from gasoline and crude oil loaded in tankships and tank barges. Almost all of these emissions were from vessels in domestic trade. About two-thirds were from inland tank barges and the rest from tankships. 2. Control and recovery of more than 90 percent of hydrocarbon emis- sions from tankships and tank barges are technically feasible with avail- able technology. Hydrocarbon vapor emissions may be abated by any of several technologies to recover or destroy hydrocarbons. Technologies vary in their efficiency of abatement, with destruction technologies generally higher in efficiency than recovery technologies. 3. Abatement of hydrocarbon vapor emissions from tank vessels raises legitimate concerns of safety, cost, economic impact, and operational reliability. With appropriate government and industry attention, these concerns can be addressed. There is as yet too little experience to project conclusively the safety of planned operations. RECOMMENDATION : In the absence of historical safety experience, the U.S. Coast Guard should employ risk analysis in assessing the safety of the various hydrocarbon vapor emission control alterna- tives. 4. Safe handling of hydrocarbon vapors will require standardized equipment and procedures, which include redundant, automated gauging and alarm devices to prevent overfilling and over- or underpressuring, as well as in-line safety devices such as detonation arrestors. RECOMMENDATION: Development and testing programs should be pur- sued to advance the state of the art in gauging and alarm systems and also to assure and improve the reliability of large (> 6-in. diameter) detonation arrestors. The gauges and alarms program should include addressing the requirements of small, unpowered vessels, i.e., tank barges. 5. Safe hydrocarbon vapor emission abatement will require trained, experienced personnel and adequate control of operations by safety 141

OCR for page 141
142 conscious management. industry is, in general, adequate. will need to be strengthened. The level of operational control in the tankship However, that in the barge industry RECOMMENDATION: The U.S. Coast Guard should revise its per- sonnel certification requirements for tankermen to ensure that responsible personnel are fully qualified and trained to maintain the safety of vapor control operations. RECOMMENDATION: The tank barge industry should undertake a voluntary safety consciousness education campaign directed to operations. This campaign should complement any federal and state regulatory initiatives. 6. Controlling hydrocarbon vapors from vessels may be cost-effective in a particular nonattainment area for ozone if tank vessels are a signi ficant source of hydrocarbon vapor emissions and cargo-loading through put is sufficient to justify control measures. 7. The economic impact of vapor control regulations will be related to how the regulations are applied: their timing, the categories of ves sels or terminals that may be controlled, and the geographical locations in which the regulations are imposed. 8. If emission controls are to be put in place, a coordinated national approach is essential to ensure the implementation of uniform and effective safety practices, with appropriate regard for the effects on interstate and international commerce. The necessary coordination could be achieved by amendments to the Federal Clean Air Act, or by a cooperative interagency program of regulatory development. RECOMMENDATION: The U.S. Coast Guard should lead the develop- ment and implementation of a coordinated program to ensure the safety and standardization of maritime hydrocarbon vapor emissions controls. Such an interagency program should involve, at a minimum, the U.S. Coast Guard and the U.S. Environmental Protection Agency, operating according to appropriate federal rule-makin~ procedures Elements of the program should include: vessel safety; terminal safety; control of emissions; and industry safety education. ---I r 9. New vapor control, recovery, and disposal methods may hold promise as replacements for currently available methods. RECOMMENDATION: A program of technical research, development, and testing should be directed to changes in operational procedures that may reduce emissions, to recovery and disposal technologies that may offer safer, less costly control measures, and to vapor barriers and foams that could help reduce hydrocarbon emissions by controlling vapor generation in cargo tanks.