Winter temperatures and snowy forecasts have made their way across many areas of the United States, and as is the case with any wintry mix, road crews appear to deal with whatever Mother Nature delivers. However, highway agencies are facing a difficult challenge to keep the public safe, while also minimizing the amount of impact on the environment.
By spreading salt onto roads before an impending storm, crews can help prevent snow or rain from being able to freeze. But while this popular snow removal method helps crews keep roadways safe, it can be harmful to our local waterways. Once all the ice and snow melts, the salt doesn’t just disappear. Instead it flows into lakes, wetlands, streams and rivers, which can be harmful to plants and animals. Yet doing nothing to the roads isn’t good for public safety.
Studies are consistently demonstrating long-term increases in chloride concentrations in Maryland’s freshwater streams, drinking water reservoirs and groundwater wells. The Maryland Biological Stream Survey, with data collected across the state over the last 20 years, has shown that streams with unnaturally high chloride levels have impaired biological condition. In fact, KCI’s own monitoring in one county’s streams at over 240 sites has shown a strong relationship between high conductivity measurements, which is a measure of inorganic ions such as chloride and impaired in-stream benthic macroinvertebrate communities.
Agencies and private sector environmental managers, aware of salt’s effects on streams and human health, are reacting with programs aimed at mitigating the impact. The Maryland Department of the Environment’s environmental managers are currently developing acute and chronic chloride criteria for our waterways, which ultimately will set limits on chloride and spur efforts to reduce salt application. KCI is currently assisting the Maryland Department of Transportation State Highway Administration in researching smart technologies to track application rates along with weather and road conditions.
Despite efforts to identify alternative methods of treatment, salt still remains one of the most effective methods used to keep roads from icing up during storms. A report published by the Maryland Department of Natural Resources states that we use between 10 and 20 million tons of salt annually in the U.S. Although there are other de-icing solutions, most are too expensive for shrinking budgets or have yet to be tested for environmental effects. Nonetheless, many states are implementing best practices to reduce the use of road salt, including:
- Training – All staff should be trained on the appropriate standards and procedures required to use equipment properly.
- Minimizing Usage – Application of salt should be minimized to the amount necessary for the conditions.
- Appropriate Storage – Salt should be stored on an impervious surface and in a solid structure that protects the product from weather and eliminates runoff.
- Equipment Calibration – Equipment should be checked periodically to ensure that the proper amount of salt is accurately being spread.
- Anti-icing – Placing a pre-treatment salt brine on the surface before snow begins to accumulate can help prevent ice and snow from bonding to the payment, and reduce the amount of overall salt usage needed during storms. According to AccuWeather.com, “It takes four times less salt to prevent ice accumulation than to remove ice after it has formed.”
- Site Specific Plans in Environmentally Sensitive Areas – Application of salt in areas that are considered sensitive should be limited. Signage may be needed to alert drivers about the reduced level of road treatment.
- Equipment Washing – Salt spreaders and plow blades should be cleaned in a location where discharge does not enter stormwater systems.
- Test and Evaluate New Methods – Continually improve operations by trying out new strategies, technologies or products.
Not only can agencies look to each other for new winter strategies, but there are also many organizations across the United States performing research, including Clear Roads, Aurora and the Road Weather Management Program. However, until a better solution is found, highway agencies will need to continue balancing environmental concerns and the public’s safety.