Proceedings magazine is a communication tool for the Coast Guard's Marine Safety & Security Council. Each quarterly magazine focuses on a specific theme of interest to the marine industry.
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60 Proceedings Fall 2015 www.uscg.mil/proceedings Response Diferences and Challenges In comparing diluted bitumen to conventional crude oil, it is helpful to keep in mind that dilbit is typically mixed with 30 percent lighter components (diluents) whereas con- ventional crude oil typically contains only seven percent lighter components. 2 So, there are two primary differences in response to spilled dilbit vs. response to spilled conven- tional crude oil: • increased airborne hazards, • increased probability for sinking. Airborne Hazards Spilled diluted bitumen presents a greater airborne hazard for responders than spilled conventional crude oil, due in large part to the greater amounts of diluent. After a dil- bit spill, the diluent (composed of the lighter hydrocarbon products) quickly evaporates, which causes elevated levels of airborne combustible gases and small aromatic hydro- carbons such as benzene, toluene, ethylene, and xylene. These airborne hazards present a health and safety risk to responders and, in a large spill, could necessitate evacuating surrounding communities. Fortunately, responders can mitigate this by using air moni- toring and personal protective equipment. In the case of a dilbit spill, air monitoring best practices include: • ensuring timely public notifcation, • establishing appropriate air monitoring thresholds, • equipping responders with air monitoring equipment and adequate personal protective equipment. Probability For Sinking Research suggests that spilled dilbit may have a higher probability of sinking upon release than a more conven- tional crude oil with a similar specifc gravity, especially in fresh water. As the lighter diluent quickly evaporates, the Over the past five years, the nation has experienced an increase in unconventional petroleum product transporta- tion. One such product is a fuel known as diluted bitumen or dilbit, which is created by blending the dense and viscous bitumen found in Canadian oil sands with lighter hydrocar- bon products known as diluents. This reduces the bitumen's density and viscosity, which allows it to fow in transport, and may add complexity to potential spill response, as com- pared to more conventional crude oils. Actual dilbit spill information and lessons learned are lim- ited, since there have only been two major dilbit spills into North American waters, both from pipelines. One of these spills occurred in the brackish water of Burrard Inlet, Burn- aby, British Columbia, and resulted in a discharge of about 59,000 gallons. The other occurred near Marshall, Michigan, where more than 840,000 gallons was spilled into a creek that led to the Kalamazoo River. 1 Environmental Response in a New Crude Landscape Responding to oil sand product spills. by Mr. kurt hAnsEn U.S. Coast Guard Research and Development Center lt sArA booth U.S. Coast Guard Offce of Marine Environmental Response Policy Adapting to New Crude Crews use "stingers" to pump water into the sediment and fush oil to the surface. Photo courtesy of the EPA.