|dc.description.abstract||To ensure roads are safe for travelers, state transportation departments often apply chemical deicers to highways during ice and snow events. The two chemical deicers used in Oregon are magnesium chloride and sodium chloride. Historically, only magnesium chloride was used. In 2012, the state began a pilot to apply sodium chloride to limited stretches of highway and saw a significant reduction in winter vehicle crashes on the affected routes. As a result, in 2017, Oregon expanded its use of sodium chloride to the major interstate highways across the entire state.
Oregon has strict environmental and sustainability rules. To ensure the state is complying with its own sustainability policies and statutes, a cradle-to-grave analysis of deicer environmental effects was conducted via individual life cycle assessments (LCA) of magnesium chloride and sodium chloride. To perform the life cycle assessments, I followed the International Organization for Standardization (ISO) standards ISO 14040:2006 (principles and framework) and ISO 14044:2006 (requirements and guidelines) (ISO, 2006a; ISO, 2006b). The LCAs reviewed the environmental impacts of the mining, production, transportation and application of each deicer using a functional unit of 100 lane miles treated. Results were categorized into climate change impact, resource consumption, eco-toxicity impact via chloride emissions, and human health impacts.
For each deicer, I analyzed the environmental impact at its maximum application rate and minimum application rate, as well as the average application rate used by Oregon Department of Transportation (ODOT) over a five-year period. When comparing the LCA results of the maximum application rate of sodium chloride to the LCA results of the maximum application rate of magnesium chloride, sodium chloride exceeded magnesium chloride in every category but one. The same was true for a comparison of the minimum application rates for each deicer. The LCA results of the average application rates showed magnesium chloride emitted slightly higher greenhouse gas emissions, consumed slightly more electricity, and resulted in higher upstream chloride emissions to surface water and soil, while sodium chloride resulted in higher human toxicity units, higher upstream chloride emissions to ground water and higher downstream chloride emissions overall.
These life cycle assessments may be used by ODOT to fully evaluate its use of sodium chloride and magnesium chloride. The LCAs provide a case study into the detailed environmental influences of chemical deicer use on highways and provide a baseline for the agency to compare alternative deicers for use in the future. Additionally, this research, while specific to Oregon, may be used by transportation departments anywhere to advise policy.||