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Modeling of Underwater Liquid Releases, Slick Transport & Evaporation V.M. Fthenakis and U.S. Rohatgi Department of Advanced Technology Brookhaven National Laboratory

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Discharge Model

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APG Spill from a Barge in Mississipi River -Baton Rouge, Louisiana

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Overview n Consequence analysis requires modeling of 1) discharge, 2) transport in water, 3) evaporation and 4) atmospheric dispersion n Previous discharge models limited to initial hydrostatic pressure difference (Dodge, 1980; Fannelop, 1994). A new discharge model was developed n Oil slick transport in rivers (Shen & Yapa, 1988) n Multicomponent evaporation ( PAVE) n Atmospheric Dispersion (ALOHA, ISC)

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Modeling n Discharge Model Phase 1- Initial hydrostatic pressure difference Phase 2- Periodic vessel movements n Verification & Sensitivity Analysis n Spreading & Evaporation Model n Application to Real Incident n Atmospheric Dispersion Modeling n Verification of Predicted Concentrations

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Discharge Model

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Discharge Due to Oscillations

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Discharge Model n Assumptions: u Isothermal Outflow and/or Inflow u Incompressible, Immiscible fluids; u Ideal gas expansion in the vessel’s void space n Based on analytical solutions for non-vented and vented vessels; discharges due to hydrostatic pressure and periodic oscillations from waves and bouncing The model predicts n Water inflows / fluid-and-water outflows with time n Change of void space and fluid inventory with time n Change of water level in the barge with time n Critical water layer thickness and inventory in steady-state

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Discharge Model -Phase 1 Verification n Experimental data (Dodge et al., 1980)

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Discharge Model- Sensitivity Analysis n Gas-phase pressure n Temperature & Saturation Pressure n Depth of the break n Area of the break n Discharge coefficient n Fluid density n Amplitude of vessel movement n Period of vessel movement

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River Spreading Modeling n Advection of the slick due to river currents and the wind n Spreading of the slick due to gravitational, inertia, viscous and surface tension forces n Multi-component evaporation

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Spreading & Evaporation Model

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Evaporation Modeling n Experimental studies -(crude oil, Payne et al. 1984; chlorobenzene and toluene, Waden and Triemer, 1989) n PAVE multi-component evaporation model u Diffusion through the liquid phase and mass transfer from surface. u Heat conduction to water, convection to the atmosphere, solar radiation, atmospheric radiation and evaporative cooling u Verified with chlorobenzene and toluene evaporation data

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Break Flow & Evaporation Rates

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Spill Area as function of Time

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Spill Area after 10 Minutes

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Spill Area after 20 Minutes

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Spill Area after 30 Minutes

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Spill Area after 45 Minutes (Leak lasted 30 minutes)

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Spill Area after 75 Minutes

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Spill Area after 100 Minutes

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A Barge Discharge Incident n A barge-tank containing APG overturned in the Mississippi River in March 1997 n For days the barge was bounced by tugboats & moved by river currents leaking APG from valves under the water n Buoyant APG fluid floated to the surface n Barge was loaded with ~400,000 gal of APG and lost at least 15% of it during the incident n The incident lasted 11 days till barge was upheld and remaining APG recovered

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Barge Incident: Predictions of Release Rates during 11 Days

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Fluid Left in the Barge (%)

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Baton Rouge -APG Spill in Mississipi ALOHA predictions on MARPLOT map

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Cumulative APG Dose (ppm-hr) 11 days -ISC3 predictions

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Conclusion n New model of underwater liquid leaks from vessel in periodic motion. n New model of spreading of a river spill. n Limited verification and sensitivity analysis showed that predictions are reasonable. n The models were applied to a known incident and the predictions were in agreement with observations and measurements. n These models may be used in real time to minimize consequences of accidental releases.

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