In areas where snow and ice are common during winter months, municipalities and transportation authorities apply deicing materials—most commonly salts, gravel or sand—to sidewalks, parking lots, and roadways to reduce ice buildup and improve traction for pedestrians and vehicles. Salts help lower the melting point of ice, allowing sidewalks, parking lots, and roadways to stay free of ice buildup during cold winters. But they are also soluble, can be toxic to some biota and environmentally persistent: applying and storing them can cause them to mix with stormwater, leading to water quality problems. Problems range from aquatic life impacts in downstream waters to contamination of drinking water supplies

Deicing Materials Management Program Considerations

During deicing materials application, certain best management practices can limit potential environmental impacts. Roadway managers and others generally outline these practices in a deicing materials management program or plan, which can help improve the efficiency of deicing efforts.

Material Selection

U.S. municipalities and transportation departments use sodium chloride for deicing more than any other material, due to its low cost and wide availability. Sodium chloride has its drawbacks, including minimal effectiveness at temperatures less than 15°F, high potential for contamination of downstream waters, and high corrosivity. Because of these drawbacks, roadway managers have looked to other chemicals or materials including other salts (e.g., calcium chloride, magnesium chloride), organic compounds (e.g., acetate compounds, glycol) and biomass-based agricultural byproducts (Terry et al., 2020; Transportation Research Board, 2007). Most of these alternative products are more expensive than sodium chloride and each has its own strengths and weaknesses. For example, municipalities should consider less corrosive alternative deicing materials like glycol, urea, or calcium magnesium acetate (CMA) for bridge deicing.

(Material from the epa.gov website)