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Using SWMM for Emergency Response Planning: A Case Study Evaluating Biological Agent Transport under Various Rainfall Scenarios and Urban Surfaces
Citation:
Yuan, L., A. Mikelonis, AND E. Yan. Using SWMM for Emergency Response Planning: A Case Study Evaluating Biological Agent Transport under Various Rainfall Scenarios and Urban Surfaces. JOURNAL OF HAZARDOUS MATERIALS. Elsevier Science Ltd, New York, NY, 458:131747, (2023). https://doi.org/10.1016/j.jhazmat.2023.131747
Impact/Purpose:
Bacillus anthracis (Ba)(the causative agent of anthrax), a spores-form bacteria with deadly nature, can be used as a biological weapon. In the actual B. anthracis attacks on the U.S. postal system in the fall of 2001, six letters, each containing 1 to 2 g of anthrax spores, caused 22 anthrax infections and 5 deaths. The large-scale outdoor spread of B. anthracis will threaten human health and cause a devastating environmental disaster. This study overcame many existing limitations, applied SWMM to model spores transport in stormwater runoff, and demonstrated the capability of a large-scale and wide-area spores contamination simulation. This paper will be of interest to both stormwater utilities and emergency responders.
Description:
To assist in emergency preparedness for a biological agent terrorist attack or accidental pathogen release, potential contaminant levels and migration pathways of spores spread by urban stormwater were evaluated using a Stormwater Management Model (SWMM) of U.S. Coast Guard Base Elizabeth City, North Carolina. The high temporal-spatial resolution SWMM model was built using spore concentrations in stormwater runoff from asphalt, grass, and concrete collected from a point-scale field study. The subsequent modeled contamination scenarios included a notional plume release and point releases mimicking the field study under three rainfall conditions. The rainfall scenarios included a 6-hour natural rainfall event on Dec. 8, 2021 and two design storms (2-year and 100-year events). The observed spore concentrations from asphalt and concrete from the actual field experiment were applied to calibrate the washoff parameters in the SWMM model. The calibrated washoff coefficient (c1) and exponent (c2) were 0.01 and 1.00 for asphalt, 0.05 and 1.45 for grass, and 2.45 and 1.00 for concrete, respectively. The final SWMM model simulated spore concentrations in runoff at times and magnitudes similar to the field study data. In the point release modeled scenario, the concrete surface generated 55.6% higher average spore concentrations than asphalt. Similarly, in the field experiment, a 175% (p < 0.05) higher average spore concentration in surface runoff was observed from concrete than from asphalt. This study demonstrates how SWMM may be used to evaluate spore washoff from urban surfaces under different precipitation amounts, intensities, and durations, and how visualized spatial migration pathways in stormwater runoff may be used for emergency planning and remediation.
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DOI: Using SWMM for Emergency Response Planning: A Case Study Evaluating Biological Agent Transport under Various Rainfall Scenarios and Urban Surfaces