Environmental Risk Assessment of Fire-Water Runoff from Vehicle Fire

By Azra Vilic
Master’s thesis in Industrial Ecology: Chamblers University of Technology
July 22, 2019

The adverse effects that fires impose on the natural environment are numerous and occur through several different mechanisms. Extinguishing a fire requires use of suppression media such as water, firefighting foam or a combination of both. Runoff from suppression media may be inherently toxic and can contaminate soils, nearby surface waters, and groundwater which can pollute local drinking water sources. Vehicle fires, due to their sporadic occurrences and their varying locations, are of interest regarding fire-water runoff. The approach to vehicle fire extinguishment depends on the location of the fire and the characteristics of the surroundings.

This project is performed in collaboration with Research Institutes of Sweden (RISE). The aim is to develop a predictive model that assists the fire-rescue service with decision making. An environmental risk assessment (ERA) of fire-water runoff from vehicle fires is used as a basis for the development of the model. Three endpoints are considered in the ERA; the soil ecosystem, aquatic life in surface waters, and human drinking water quality. The model, called the Fire Impact tool, provides quantitative values regarding how firefighting tactics impact expected soil excavation, the volume of water required to dilute fire-water runoff to reach surface water guideline values, and the minimum distance between a vehicle fire and contaminated groundwater wells.

Users of the tool can make simple predictions regarding the environmental impacts and make informed decisions about vehicle fire extinguishment before a fire occurs. The results provided by the tool suggest that environmental impacts due to fire-water runoff are largely affected by the volume of extinguishant used. Results also show that the environmental impacts due to additives, such as firefighting foams, are significantly larger than the impacts due to contaminants stemming from the vehicle fire itself.

The ERA used to develop the Fire Impact tool is limited to environmental impacts due to fire-water runoff on three endpoints. It does not include all possible environmental impacts that can arise due to vehicle fires. Since the Fire Impact tool serves as a basis for decision-making, it is essential that users of the tool are familiar with the tool’s assumptions and limitations.

Keywords: vehicle fire, environmental risk assessment, fire-water runoff, ecotoxicity, firefighting tactics, monte carlo simulations