Putting our roads on a low-salt diet

We woke last Friday to a world of wonder and white — the first snow.

Beyond the wonder, though, we knew there was the reality of making the roads safe for travel in the winter ahead.

We deliver our newspaper every week in a 20-year-old pickup truck that had belonged to my husband’s father. When he died, my husband drove his father’s truck from Oregon, where he grew up, across the country to New York where we now live.

Like a Florida car, an Oregon truck has no rust. But that was six years ago and, after five New York winters, the pickup has rust.

Road salt, which is 40 percent sodium and 60 percent chloride, rusts not just our vehicles but our bridges and the reinforcing rods in concrete. One study estimated that salt corrosion costs the United States $16 billion to $19 billion per year.

Salt wasn’t used on roads in the United States before World War II. And, since 1975, use of road salt has doubled. Besides being used on paved roads, road salt is applied to sidewalks, parking lots, and driveways.

The problems go beyond the damage to valuable infrastructure. Road salt accumulates in both surface and groundwater, which is harmful for humans as well as plants and animals. It can take decades for road salt to flush out of a watershed.

Besides the dangers of people drinking salty water, high chloride increases the corrosion of poisonous lead from old water pipes, according to research by the federal Environmental Protection Agency and the United States Geological Survey.

Any of us driving on major highways can see the effect salt has had on roadside vegetation, but we don’t often see more sinister effects. The environmental impact can be far-reaching and irreversible.

When the ice melts, the salt flows into surrounding streams, lakes, and grassy areas. The salt water is more dense than fresh water so it pools at the bottoms of lake and ocean beds. This deprives amphibians and fish of needed nutrients trapped beneath the salt cloud. 

 A study that traced salt levels in the Mohawk River, from 1952 to 1998, discovered concentrations of sodium increased by 130 percent and chloride increased by 243 percent; road salt was the primary reason as the surrounding area became more developed. The United States Geological Survey estimates that 40 percent of the nation’s urban streams have chloride levels that exceed safe guidelines for aquatic life, largely because of road salt.

Many studies have found that chloride from road salt can kill plants, fish, amphibians like frogs and salamanders, crustaceans, and other organisms. Also more salt in the water of lakes and ponds make it denser and affects circulation, keeping oxygen from reaching the bottom layer of water.

Road salt can also change the chemistry of a body of water, reducing the nutrient load.

So, what’s the alternative?

We thought, when we started researching this editorial, that the answer would be sand, which we’ve seen used effectively on mountain roads we’ve driven in the Adirondacks.

But, as it turns out, abrasives have problems, too.

 Sand is more costly than salt, it doesn’t melt ice the way that salt does — and it also creates environmental problems. Once sand is degraded by traffic, very fine particles get into the air. Also, the gradual buildup of sand in the bottoms of streams or rivers is harmful to aquatic life.

A study described by the Cornell Local Roads Program shows how and why Warren County, in the Adirondacks, made the change from using abrasives to prioritizing road salt.

Most of the western watershed of Lake George is in Warren County. In the early 1990s, the loadings of silt and abrasives accumulating in the lake were generating a high level of environmental concern, the Cornell program reports.

The state and Warren County installed containment features to trap silt and abrasives before they reached Lake George and also used aggressive sweeping programs to pick up the sand before it entered the drainage system.

Then, Warren County, working with the National Cooperative Highway Research program, which Cornell called “a match made in heaven,” conducted a study over three winters that showed an equal or higher level of service was provided at less cost when road salt was prioritized over abrasives.

Further study, reported on by the Cornell program, examined the effectiveness of salt treated with a liquid chloride solution and correlated it to truck speed and salt distribution systems.

Two salt types — treated and untreated — were compared as were two distribution systems, and three truck speeds: 25, 35, and 45 miles per hour. Treated salt performed significantly better at all speeds and through both distribution systems. A cross-conveyor type of distribution performed slightly better than a Y-chute system.

However, truck speed had the most profound effect on how much salt was lost to bounce and scatter. A truck driving at 25 miles per hour lost only 9 percent; a truck at 35 miles per hour lost 32 percent, and a truck driving at 45 miles per hour lost 45 percent of its salt to bounce and scatter.

Clearly, highway departments that follow the results of this study — distributing treated salt at 25 miles per hour — will not just reduce salt waste but will reduce the resulting road and vehicle deterioration as well as doing less harm to the environment.

A variety of other tactics are being tried by highway departments across the nation. Many are using a 23-percent salt-brine solution to pre-treat roads before the start of a storm, which may result in a 75-percent savings in total salt applied.

Some departments are pre-wetting salt before putting it on the roads, which can reduce salt infiltration to aquifers by 5 percent and also reduces spray and kick-up of salt grains.

Several states adjust levels of service for conditions. In Vermont, for instance, the transportation department uses the slogan “safe roads at safe speeds,” meaning roads are not necessarily bare after a snowstorm.

In Minnesota, the department of transportation is pioneering the use of what it calls “living snow fences,” barriers made of trees, shrubs, and naive grasses that can prevent snow from drifting onto roads.

Many departments are using agro-based alternatives for de-icing although salt is the active ingredient in most of them. These include cheese and pickle brines; fermentation products from making beer and wine; and de-sugared molasses, a byproduct of sugar beet producing, known as beet juice.

Beet juice lowers freezing temperature and melts ice as the sugar it contains dissolves on the road but the sugar is a fertilizer that feeds algae growth.

Research is also underway that may one day make road salt obsolete — for example, solar panels embedded in pavement are being tried in parking lots in the state of Washington. In Europe, under-road heating systems keep some highways free of snow.

In the meantime, as we urge our local highway departments to stay on top of the most efficient systems for distribution of salt, we note that each of us can make a difference in how we handle the ice and snow at our own homes or businesses.

We should use deicers sparingly. If we shovel snow as soon as it falls, and keep on shovelling as it comes down, it won’t have a chance to turn icy.

Once snow starts to melt and turn to slush, we should remove the slush before it turns to hard ice again.

We can use beet juice, coffee grounds, or sawdust — all of which will create traction without being as damaging as salt.

Although many of us have been staying home and working from home of late to stem the spread of the coronavirus, we know we can’t go back in time to the days when roads often remained snow-covered all winter, with horse-drawn sleighs used for transport.

Our economy and safety depends on cleared roads.

We also can’t leap-frog ahead to an era when solar highways and under-road heating systems powered by renewable energy sources are a reality. We can certainly lobby for such developments.

Since ancient times, people have known that salt kills plants and would bury it in the fields of their enemies. We have the science now that shows how far-reaching the harm is.

Here, in the present, we can recognize that human beings must take care of the natural world and walk as lightly as we can upon its surface. 


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