PW14 Probabilistic Ecological Risk Assessment
Exhibit Hall
8:00 AM - Wednesday

(PW235) Probabilistic Impact Evaluation of Oil Spills in the Columbia River and Coastal Washington Waters.

French-McCay, D1, Rowe, J1, Whittier, N1, Sankaranarayanan, S.1, 1 Applied Science Associates, Inc., Narragansett, RI, USA

ABSTRACT- Oil spill fate and effects modeling and analysis were performed to evaluate the potential impacts of oil spills that could occur along shipping routes and the implications of spill response options being considered by the Washington State Department of Ecology in their rulemaking related to oil spill preparedness (WA State Contingency Plan Rule). The impacts of potential spills in Washington′s outer coast, sound and river environments were modeled varying response options and operational timing, including use of conventional mechanical containment and recovery operations; dispersant application with concurrent mechanical containment and recovery; and in-situ burning with concurrent mechanical containment and recovery. US Coast Guard federal response capability standards, current Washington State standards, and potential theoretical higher response capability standards were simulated for scenarios involving spills of crude oil, bunker fuel and diesel into Washington waters (Strait of Georgia, Strait of Juan de Fuca, outer coast, and lower and upper Columbia River). The modeling was performed in probabilistic mode, randomly varying location along tanker routes, spill date, and time, and so environmental conditions during and after the release among potential conditions that would occur. The model results were analyzed to estimate mean, standard deviation, and 5th, 50th and 95th percentile results for surface water and shoreline oiling, water column and sediment contamination, and biological impacts. Results were compared among response options to evaluate the environmental tradeoffs of dispersant use (i.e., effects on birds and intertidal habitats versus fish and invertebrates in the water column), as well as the benefits of additional and earlier mechanical removal activities. The costs of maintaining various response strategies will be compared to resulting benefits, measured as reduction in impacts and monetary damages, as part of the rulemaking process by the Washington Department of Ecology.

Key words: oil fate and effects, probabilistic risk assessment, Columbia River, Washington

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