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Rainfall Washoff of Spores from Concrete and Asphalt Surfaces
Citation:
MIKELONIS, A. M., W. CALFEE, S. LEE, A. Touati, AND K. RATLIFF. Rainfall Washoff of Spores from Concrete and Asphalt Surfaces. WATER RESOURCES RESEARCH. American Geophysical Union, Washington, DC, 57(3):e2020WR028533, (2021). https://doi.org/10.1029/2020WR028533
Impact/Purpose:
The goal of this work was to better understand the rainfall removal of spores from concrete and asphalt surfaces and to estimate wash off coefficients used to inform storm water modeling of biologically contaminated urban settings. Remediation after natural and man made biological contamination disasters can span months to years, during which time rain events may drastically change the spatial distribution of contamination. This was achieved through use of a rainfall simulator and coupons inoculated with spores. Curve fitting and statistical analysis determined the coefficients appropriate for use in storm water models to predict the first-flush of spores. The data also demonstrated that material type impacts removal of spores. This paper is of interest to emergency respondents, storm water managers, and storm water modelers.
Description:
Understanding the migration path of pollutants is critical to protecting human and environmental welfare, particularly in population-dense settings with a high fraction of impervious materials that contribute to potentially high pollutant wash off. This research measured the removal of Bacillus atrophaeus and Bacillus thuringiensis kurstaki spores (common surrogates for Bacillus anthracis, the causative agent of anthrax) from concrete and asphalt coupons using simulated rainfall. Spore removal was measured under environmentally relevant rainfall rates of 16 mm/hr – 91 mm/hr. The study assessed goodness-offit for the Storm water Management Model’s (SWMM) exponential wash off function compared to an alternative two stage exponential removal function. Spore wash off was not significantly different for the two types of spores used in this study, but there were significant differences in wash off from asphalt versus concrete with more wash off occurring from asphalt. Average kinetic energy of the storm event impacted wash off from asphalt, but not concrete. The median values for SWMM’s exponential wash off function coefficients were determined to be 0.01 for c1 and 0.57 for c2, however the proposed alternative two-stage removal function performed better than the SWMM fit in terms of goodness-of-fit criteria.
URLs/Downloads:
DOI: Rainfall Washoff of Spores from Concrete and Asphalt Surfaces
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