Overview
Relevant Activities
Role of Local Governments
U.S. EPA Resources
Each winter, state, county, and local transportation departments stock their arsenal with the tools necessary to face whatever winter storms may bring. This includes a variety of chemicals to melt snow and ice. This preparedness has a high price tag: in the U.S., an estimated $2 billion is spent each year on chemicals, materials, labor, and equipment for winter road maintenance.
The most used and economical deicer is sodium chloride, better known as salt; 15 million tons of deicing salt are used in the U.S. each year. Salt is effective because it lowers the freezing point of water, preventing ice and snow from bonding to the pavement and allowing easy removal by plows. However, the use of salt is not without problems. Salt contributes to the corrosion of vehicles and infrastructure and can damage water bodies, groundwater, and roadside vegetation. These issues have led to the use of other chemicals as substitutes for and supplements to salt. Other deicing chemicals include magnesium chloride, potassium acetate, calcium chloride, calcium magnesium acetate, and potassium chloride (these are described below). Abrasives such as sand are often used in conjunction with deicing chemicals to provide traction for vehicles, particularly on corners, intersections, and steep grades. However, when sand is overused, it often ends up in the environment, either as dust particles that contribute to air pollution or in runoff to streams and rivers.
Airports present another area of concern with respect to deicing chemicals. The Federal Aviation Administration (FAA) requires that aircraft surfaces be deiced and anti-iced to ensure the safety of passengers. However, when performed without prevention measures in place, airport deicing operations can contribute to contamination of groundwater and surface water supplies. EPA promulgated the Airport Deicing Effluent Guidelines in 2012 (40 CFR Part 449). The requirements generally apply to wastewater associated with the deicing of airfield pavement at commercial airports. The rule also established New Source Performance Standards for wastewater discharges associated with aircraft deicing for a subset of new airports. These requirements are incorporated into NPDES permits.
- Precipitation Management & Preparation
- Bridges, Roads, and Other Infrastructure Construction & Maintenance
- Transportation Planning, Operation, and Management
In areas where snow and ice are common during winter months, local governments (e.g., their transportation divisions) apply deicing materials to sidewalks, parking lots, and roadways to reduce ice buildup and improve traction for pedestrians and vehicles. Local governments in choosing the materials they use for deicing should be aware of the impacts of those materials on the environment and remain in compliance with any state or federal laws regarding their use.
U.S. Environmental Protection Agency Resources
- Deicing Material Application and Storage. Provides best practices on the selection and use of deicing materials.
- Source Water Protection Practices Bulletin: Managing Highway Deicing to Prevent Contamination of Drinking Water. Provides information on managing highway deicing chemicals.
- Airport Deicing Effluent Guidelines. Provides an overview of airport deicing requirements and regulations.
- Source Water Protection Practices Bulletin: Managing Aircraft and Airfield Deicing Operations to Prevent Contamination of Drinking Water. Addresses two basic types of deicing/anti-icing operations at airports: the deicing/anti-icing of aircraft, and the deicing/anti-icing of paved areas including runways, taxiways and gate areas.
- Salt. Provides an overview of the risks that salt presents to the environment and links to resources for salt management and winter maintenance guidance.
- EPA Safer-Choice Certified Deicers. Provides a list of deicing materials certified as Safer-Choice products.