Salting our roads — and water and fields

There are always trade-offs, it seems.

In “Inherit the Wind,” the Henry Drummond character (Spencer Tracy in the film version) sums it up: “Progress has never been a bargain; you have to pay for it. Sometimes I think there’s a man who sits behind a counter and says, ‘All right, you can have a telephone but you lose privacy and the charm of distance. Madam, you may vote, but at a price; you lose the right to retreat behind the powder puff or your petticoat. Mister, you may conquer the air, but the birds will lose their wonder and the clouds will smell of gasoline.’”

As winter settles in this month, people need snowy streets and roads cleared to travel safely and get to work. However, the main tool is road salt, which dissolves in water and runs off into ditches and lakes, streams and sewage-treatment plants, potentially affecting plants, animals and vegetation. It also can seep into groundwater where it can remain for years, accumulate from previous seasons and enter wells and other supplies of drinking water which can affect taste and people on restricted-sodium diets.

First used in 1938, road salt is relatively cheap and effective. It lowers the freezing point, so snow melts until temperatures drop to about 0 degrees instead of 32 degrees before freezing. Illinois was one of the states examined in studies showing road salt cuts snowstorm wrecks by 88 percent, according to research by Marquette University, and the negative economic cost of road closures is costlier than snow removal, says a report by the consulting service IHS Global Insight.

Peoria County uses about 3,000 tons of salt and the city more than 6,000 tons during a “typical” winter of 24.5 inches accumulation. Nationwide, public services handle more than 12 times the amount of salt used by the food-processing industry, according to the U.S. Geological Survey (USGS).

Peoria County plows more than 300 miles of road and the city 478 miles (measured one-way, not both directions or multiple lanes).

Road salt has three costs: the salt and labor to use it; indirect expenses for repairs or replacement of corroded concrete, bridges, vehicles and equipment; and long-term remediation of removing salt from water. (Salt prices are variable; Peoria County pays $55/ton, down from $95/ton in 2014; the city pays $58.50/ton, down from more than $80/ton.)

Environmental consequences can be the most expensive.

“Like most chemicals, too much salt is toxic,” wrote William Schlesinger and Stuart Findlay of the nonprofit Cary Institute of Ecosystem Studies. “And humans are inadvertently increasing the salinity of freshwater resources through routine road-salt application. If salt continues to accumulate at its present rate, in our region many surface and well waters will be unhealthy for humans and wildlife by the end of this century.”

Salt pollution, measured by the concentration of chloride (road salt is sodium chloride), is substantial, according to the USGS, which found that 84 percent of northern U.S. streams have toxic levels of chloride. Levels are highest in winter when road salt is prevalent.

The results can hurt freshwater species, soil, vegetation and wildlife, which can be lured by the artificial “salt licks” where animals near rural traffic can become road kill.

Salting roads undoubtedly saves lives, but, arguably, so had snow fences, which the Illinois Department of Transportation dramatically scaled back due to costs, farmers’ permission and deterioration of stored wooden slats. (IDOT also changed its “bare pavement” policy removing all snow and ice from roads, moving to a “25-percent coverage” approach, where two wheel paths in each lane are acceptable.)

There are innovations: adding abrasives such as cinders or sand, “pre-wetting” salt for better control and adherence; monitoring weather forecasts to apply salt just before accumulation; and supplementary substances such as (biodegradable) sugar-beet juice, cheese brine (used in Wisconsin), pickle juice (used in New Jersey) and potato juice (used in Tennessee).

“It is not a cookie-cutter decision,” says Sie Maroon, superintendent of operations with the city. “All storms are different and in some cases unique. It requires us to pay attention to pre-storm and during-the-storm forecasting to make adjustments and utilize ‘best practices’ for which application or method is best to use. “We do use alternative products,” he continued. “In addition to rock salt, we use [liquid] calcium chloride. Recently, we have been using another liquid product that we produce, a brine solution, a water and rock-salt combination.”

The city pre-treats hills and overpasses with the brine solution before storms and “pre-wets” its salt when temperatures drop below 20 degrees.

The county also fine-tunes its applications.

“We treat the salt with beet juice so it can be effective at colder temperatures, as well as minimizing the ‘bounce’ you see when it comes off trucks’ spinners,” said Amy McLaren, county engineer with the Peoria County Highway Department.

That’s good news.

“Research indicates that we can achieve safety while being more efficient and careful with our road salt,” according to the Cary Institute. “By combining efforts to improve efficiency in road-salt use with alternative chemicals in targeted areas, we can make a difference and improve conditions for ourselves and future generations.” Of course, an ideal approach to snow removal hasn’t been perfected.

“With every snow/ice storm that we encounter, we operate with the idea of balancing safety and convenience for motorists as well as keeping in mind what impacts the snow and ice control products have on the environment,” Maroon said.

McLaren echoed that concern: “We are very mindful that too much salt can negatively impact the environment and try to balance the need for clean roads with appropriate usage,” McLaren said. “Our drivers take clearing their routes seriously. We are plowing for our neighbors, friends and family out in the county.”

Amy McLaren of the Peoria County Highway Department

Amy McLaren, engineer with the Peoria County Highway Department, shows some of the 3,000 tons of road salt used in Peoria County each year. An additional 6,000 tons are used by the city. (Photo by Bill Knight)

Road salt’s environmental impacts

Chloride: The chloride component of chloride-based deicers does not easily precipitate, is not biodegradable, is not readily involved in biological process, and does not adsorb significantly
to mineral/soil surface

Water: Since chloride doesn’t bind to soils, chlorides that enter the subsurface with infiltrating water may reach the groundwater table. Also, surface water is disrupted because saltwater
has a higher density than fresh water and will sink, resulting in chemical stratification and altered mixing patterns.

Vegetation: Roadside vegetation can be harmed by absorption of chloride through plant roots or from accumulating on foliage and branches. The effects are comparable to drought, with stunted growth, brown and falling leaves/needles, dying limbs, and premature plant deaths.

Soil: Accumulation of chloride can result in reduced soil permeability and fertility, plus increased soil alkalinity and density.

Bill Knight

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