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

Discharge Model

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

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)

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

Discharge Model

Discharge Due to Oscillations

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

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

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

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

Spreading & Evaporation Model

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

Break Flow & Evaporation Rates

Spill Area as function of Time

Spill Area after 10 Minutes

Spill Area after 20 Minutes

Spill Area after 30 Minutes

Spill Area after 45 Minutes (Leak lasted 30 minutes)

Spill Area after 75 Minutes

Spill Area after 100 Minutes

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

Barge Incident: Predictions of Release Rates during 11 Days

Fluid Left in the Barge (%)

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

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

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.