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Accident Reconstruction And Plume Modeling Of An Unplanned Ammonia Release


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A. Daly, P. Zannetti & M. Jennings


Accident reconstruction and plume modeling of an unplanned ammonia release A. Daly1, P. Zannetti1 & M. Jennings2 1The EnviroComp Institute, Fremont, California, USA 2San Jose State University, San Jose, California, USA Abstract This paper describes the study we performed in relation to an accidental release of ammonia at a plant in Luling, Louisiana. Our work involved the understanding of the dynamics of the accident, the evaluation of the emission scenario, the computer modeling of the ammonia plume transported by the wind, and the visualization of our results for the purpose of litigation support and presentation to a non-technical audience. The emission scenario was complicated because of a high-velocity jet release and stormy weather conditions. We used emissions and weather data available at the site, in addition to other local weather data. We also used an EPA-approved model to simulate the transport and dispersion of the ammonia cloud and calculate ground-level concentrations of ammonia over the period of concern (a 2-hour interval). We concluded that maximum hourly concentrations of ammonia, beyond the industrial fenceline in the local community, were around 0.20 ppm, which is far below existing levels of concern. However, our odor modeling calculations showed that short-term concentrations were potentially larger, and may have reached 5 ppm for very short periods. Our estimated concentrations of ammonia were validated by the locations and times of local odor complaints as well as in-situ measurements. Finally, we visualized the plume by applying a simplified version of our MONTECARLO particle model and creating a computer animation of plume concentrations, in order to illustrate the dynamics of the events to a non-technical audience. Keywords: accident reconstruction, air quality modelling, ISC3, MONTECARLO, plume modeling.


accident reconstruction, air quality modelling, ISC3, MONTECARLO, plume modeling