[en] The objectives of this workshop were to examine the role of dispersants in spill mitigation and Canada's dispersant approval process. Participants identified current stakeholders goals and concerns, as well as areas that need improvement. Industry has identified certain problem spills for which dispersants would improve response capabilities. Dispersant use on spills requires that lead agencies in partnership with the regional environmental emergencies team (REET) make a case-by-case assessment regarding dispersant use. It was suggested that timely and favourable decisions from REET cannot be reliably predicted. Industry operators wish to streamline the approval process for dispersant use before devoting resources to dispersant planning. REET's position was that government guidelines regarding dispersant use are in existence, but need updating. Historically, REET decisions on dispersants have been made within 4 hours, with dispersants being approved where merited. Operators have frequently requested permission for dispersants although spill conditions were not appropriate and no advance preparation had been made for their use. A number of spill scenarios were identified by oil industry operators. The preparations needed to make dispersant use possible in Canada were outlined. Regulatory controls over dispersants were reviewed. It was noted that dispersants can minimize contamination risks for both offshore and nearshore spills. However, the dispersed oil can pose risks to fish stocks. Dispersant research needs were reviewed. It was concluded that several types of countermeasures should be used when spills occur in Atlantic Canada. Dispersants should be used under conditions when they will be effective, and where potential environmental benefits outweigh drawbacks. Time delay is a critical factor in determining the effectiveness of dispersant operations. In order to maximize the potential effectiveness of dispersants, both industry and government must plan accordingly. 8 tabs

[en] The operational and environmental issues associated with dispersant use to clean up oil spills in the Gulf of Mexico (GOM) was assessed. The assessment included an examination of the dispersibility of oils plus the capabilities and limitations of spray platforms as well as the net environmental benefit of dispersing spills. Spill scenarios involving typical spill types, oil types, sizes, locations and environment were also analyzed. Gulf oils are typically light and apparently dispersible when they are fresh. The impact of weathering on dispersibility of GOM oils was assessed by analyzing oil spill scenarios. The time window (TW) for dispersion was estimated by oil fate modeling. Only 28 per cent of the oils produced in the GOM have been sufficiently characterized to allow for modeling. The majority of oils produced in the GOM have TW of a few days or longer, and are therefore amenable to chemical dispersion. The maximum theoretical dispersant delivery capacities of a range of spraying platforms were estimated using spreadsheet models. The environmental benefits of using dispersants were greatest in situations involving spills of manageable size, with persistent but dispersible oils and with a TW of more than 24 hours. This is because the oils would otherwise persist long enough to reach the shorelines where they would pose a threat. This analysis also suggested that the net environmental benefit is greater in a blowout spill than in a comparable batch spill. 23 refs., 5 tabs., 2 figs

[en] The Arctic holds the world's largest remaining untapped gas reserves and some of its largest undeveloped oil reserves. A significant proportion of these reserves lie offshore, in the Arctic's shallow and biologically productive shelf seas. This paper describes the results of a recently-completed study commissioned by the environmental studies research funds to document the current state of knowledge with regard to counter-measures for oil spills that might result from exploration and production activities in the Canadian Beaufort Sea. It provides a brief overview of the main advances in the past 20 years and the state-of-the-art for each of the main categories of counter-measures. An additional goal of the study was to identify key issues of concern regarding planning and response to spills in the Beaufort, to provide a current reference document for use by industry, regulators and the public, and prepare a geographic database of coastal resources, vulnerabilities and sensitivities that may influence the choice of oil spill containment and recovery methods.

[en] The technical issues regarding the use of dispersants to clean up oil spills from offshore production sources and transportation sources in California were assessed in this study which examined both operational and environmental issues. The operational issues included the dispersibility of produced and imported oils, along with the capabilities of California response resources to deal with typical spills and limiting environmental impacts to offshore environments. The environmental issues include the risks associated with typical spills and potential net environmental benefit of chemically dispersing oil spills. Most crude oils produced offshore California are heavy and border on the undispersable range, but the imported crudes are somewhat lighter. Modeling has shown that most produced oils and some imported oils emulsify quickly and weather more quickly to the point where they are no longer dispersible. There is a very narrow window of time for chemical dispersions to be used effectively. The net environmental benefit analysis demonstrates that the use of dispersants lessens the total environmental impact of spill scenarios. It was emphasized that it is necessary to act quickly if chemical dispersion is to be effective. Rapid response strategies are needed, including locally based vessel and helicopter spraying systems. 19 refs., 8 tabs., 1 fig

[en] The purpose of this study is to use wave-tank testing to predict spill behavior at sea. Spill researchers have used large outdoor wave tanks like Ohmsett to simulate at-sea conditions as the method of oil spill research and testing for more than 40 years. However, facilities such as Ohmsett, which is the largest of these wave tanks used for studying chemical dispersion of oil spills, are seen to be in need of further development to keep pace with new concerns. Over the past ten years, Ohmsett researchers have been committed to addressing decision-makers' questions concerning the inapplicability of bench-scale methods and the difficulty of sea tests. The factors they focused on were the limited operational effectiveness of dispersant s; the persistence of dispersant in treated oil slicks; procedures for monitoring effectiveness of dispersant applications; and the ability to extrapolate from bench-scale tests to predict dispersant performance at sea. Overall this paper presents the challenges of this work and briefly reviews the results so far.

[en] The Special Monitoring of Applied Response Technologies (SMART) is a written dispersant effectiveness monitoring protocol developed in the United States in the mid 1990s. It has been the subject of considerable review and research since its development. This paper reported on the 2007-2008 review of the SMART dispersant effectiveness monitoring protocol which involved the following 3 tasks: (1) stakeholders reviewed their experience with SMART and identified the key deficiencies in the current protocol, (2) the SMART monitoring experience gathered during dispersant effectiveness testing at the Ohmsett National Oil Spill Response Test Facility was reviewed to evaluate the usefulness of existing SMART decision criteria, (3) available commercial off-the-shelf instruments (COTS) were surveyed to identify the instruments that might be more effective or simpler to use than those presently in use. The review concluded that the three-tiered approach in SMART was appropriate, but better guidance was needed for users. In addition, the fluorometer historically used for monitoring of dispersed oil was found to have several operating challenges and should be replaced with more modern equipment. It was recommended that all U.S. government sponsored monitoring teams work with identical instruments and operating protocols. The COTS survey identified 6 potentially suitable submersible and field-portable fluorometers and three particle-size analyzers. 26 refs., 5 tabs., 1 fig