Integration of Local,
State, and Federal Resources in Emergency Management
On
Chris Alverson of the
Safeguards, Security, and Emergency Services Division at the Savannah River
Site and a member of the Graniteville Volunteer Fire Department presented
operational concerns from an emergency responder’s perspective including actual
911-calls, personnel issues, and the interaction of
first responders with local, state, and federal resources, particularly the
SRNL Atmospheric Technologies Group (ATG). An existing mutual aid agreement
with Aiken County allowed ATG meteorologists, Charles Hunter, Matthew Parker,
Robert Addis, Robert Buckley, and Allen Weber, to provide atmospheric
conditions and forecasts through the Regional Atmospheric Modeling System
(RAMS, version 4.3.0) and two transport models (LPDM and PFPL).
At 0240 LST (0740 UTC), over 90 tons of liquid
chlorine, cresol, and sodium hydroxide were released into the environment over
a short time span. The liquid chlorine,
highly volatile at standard atmospheric conditions, rapidly vaporized to form a
dense and highly toxic airborne cloud.
Using meteorological data from a local network of observations stations,
and output from an operational mesoscale forecast model, ATG scientists applied
atmospheric transport and dispersion models to estimate potential downwind
hazards. Initial hazard estimates were
performed with ATG’s Puff/Plume code, a segmented trajectory Gaussian
dispersion model. Additional plume transport
calculations were performed with a Lagrangian particle dispersion model (LPDM),
which provides full utilization of 3-dimension wind forecasts provided by the
operational mesoscale model. Results
from the models were posted to a designated external web site, enabling local
emergency management officials and the SC DHEC to assess the appropriateness of
evacuation orders within the significant threat area over the several days of
response and recovery operations that followed the derailment.
The ATG also conducted a detailed post-accident
analysis of the chlorine release. The operational
configuration of the mesoscale forecast model uses a 2-km horizontal grid
resolution. To account fully for local topographic characteristics, the model
was modified to include nested grids of 500 m and 125 m centered on the
accident site. Fine resolution topography from digital elevation maps was used
to characterize the Graniteville area and archived analyses from the Rapid
Update Cycle (RUC) model provided initial and lateral boundary conditions at
3-hr intervals. Simulated values of wind speed and direction were compared with
regional observations and were seen to capture the flow for this day.
Application of the fine-scale meteorology was used to illustrate pollutant
transport in a general sense over an 18-hour period following the accident, indicating
transport to the northeast. In addition, the Hazard Prediction and Assessment
Capability (HPAC) was used to simulate migration of
the dense gas immediately following the accident. The predicted plume location
is supported by the location of fatalities that occurred in the immediate area,
as well as visual evidence of damage to plant life. Based on the detailed
modeling, the dense chlorine plume was gravity driven and flowed toward lower
elevation to the southwest and against the prevailing wind direction. Subsequent transport was toward the
north-northeast as the dense cloud became more dilute and subject to behavior
as a passive gas.
The National Weather
Service’s
The Mini-Technical
Conference also highlighted the ideal relationships that should exist between
the private, public, and government sectors of the meteorological and
climatological communities, which Matthew Parker of SRNL emphasized in his
presentation on the American Meteorological Society’s Commission on Weather and
Climate Enterprise (WCEC). The AMS is poised to improve communication through
the WCEC, which is the first new Commission in the last 30 years. Mr. Parker’s work is a reflection of the
dedication of ATG founders, Todd Crawford and Ben Rusche, (in attendance at the
meeting), to the integration of weather science across a broad spectrum of
disciplines that continues to foster the professional growth of the atmospheric
science community in
Jason Caldwell
Secretary/Treasurer
Palmetto Chapter of the American Meteorological
Society
803-734-0039