On-Water Response During Day 1-3
Spill response experts agree that spills which have had obvious and significant biological impacts have always involved nearshore or intertidal accumulations of oil (10). A successful response is one that prevents or minimizes oil from reaching sensitive areas, preferably by removing it from the water but failing that, by dispersing it into deep water where its impact will be less damaging.
The most critical time period during an oil spill response is early in the spill while the oil is still on the water. During that early period, oil is in its most confined and thickest state. All response options, be they mechanical, dispersion, or burning, have highest efficiency and effectiveness when applied as soon as possible once the spill has occurred. In the case of the VALDEZ, a number of factors impeded the use of the response options specified in the area contingency plan. First, mechanical equipment was for the most part unavailable in the first few days because the barge used for storage and transport of this equipment was under repair. Second, for a spill as large as the VALDEZ, air application of dispersants is practical and desirable, In fact, Alaska was one of the few states in the U.S. during 1989 to have defined areas where dispersants were pre-authorized for use. However, pre-authorization still required specific approval by the FOSC prior to use. Unfortunately, a key window of opportunity for dispersants was missed because the on-scene Coast Guard Commander decided to implement effectiveness trials to demonstrate conclusively to state agencies and to private interest groups, such as fishermen that dispersants would work in this situation. It took 2 days to satisfy all parties that dispersants were indeed effective for this spill but by then a major storm arose, whipping the oil into mousse emulsion and distributing it over a large area of Prince William Sound. The delay caused by testing demands meant that the main response weapon, the only practical one available, was not allowed to be used during the most critical part of the spill. An excellent opportunity was lost and the result was widespread oiling of shorelines in Prince William Sound and in the Gulf of Alaska.
Ironically, at about the same time a special committee, set up by the U.S. National Research Council to review dispersants, issued its final report following several years of study. It concluded that under proper conditions, dispersant use can result in a net benefit to the environment and recommended that dispersants should be considered as a potential first response option to oil spills, along with other response options. Had this report issued earlier, it is possible that the Coast Guard would not have been as hesitant to approve immediate dispersant application. On hearing of the hesitation to approve dispersants for the VALDEZ spill, Dr. James Butler, Head of the NRC Committee on Effectiveness of Oil Spill Dispersants commented that this would have been an excellent opportunity for dispersant use because the added energy provided by the storm would have helped disperse the oil into the water and then tidal currents would have carried it to the open ocean where it would be still further diluted, rendering it much less harmful than the untreated slick (4).
Application to Today : In the U.S.,there has been significant change in attitude toward dispersant application since VALDEZ spill. By the end of 1997, it is expected that most of the U.S. coastal states will have pre-authorized zones for dispersants. This means that when certain conditions are met, dispersants can be approved by the on-scene commander, without need to consult with other agencies or with other interested parties, such as fisheries groups. My company is a strong supporter of using all response options available in as timely a manner as possible. But we are particularly supportive of dispersants because we believe that for large spills, dispersants can sometimes be the only practical response option (5). Because they are applied by aircraft, the area that can be covered in a given time can be 10-40 times as much as by a fleet of skimmers, which can be limited by maximum speed requirements and by adverse weather conditions. This is especially true if the spill is many miles offshore. Also, we feel it is not wise to spent excessive time evaluating effectiveness, when it could result in missing the most critical response window of opportunity, as happened in the VALDEZ incident. The U.S. Coast Guard is now more pro-active in recommending dispersants, and for the Gulf of Mexico, it has established a target of applying dispersants within 5-6 hours after the start of a spill.
In addition, recent advances in dispersant formulation make the latest generation of products effective for a wider range of oils, making the need for tests less necessary than in the past. For example, COREXIT 9500 - developed by Exxon as part of a new research effort commissioned after the VALDEZ - can disperse even the heaviest bunker oils as long as they are still fluid enough to spread (6). Moreover, earlier worries about adverse
