Treated Salt Helps Deprtment Of Public Works Balance Safety, Environmental Impact
When it comes to the chemical composition of ice melting road salt being used locally this winter, Newtown’s Department of Public Works (DPW) drives a fine line between safety and environmental stewardship.
Public Works Director Fred Hurley recently provided an update on the materials being used to melt or prevent icing on Newtown roads after queries from Newtown Bee readers asking about how much potential harm the ice busting salt might be doing to the local environment and water tables.
“We’re very sensitive to the harm that salt can do,” Mr Hurley said in an interview following the most recent storm that dropped several inches of snow. “That’s why we typically use a 50/50 mixture of salt and sand in our trucks — and we incur the extra expense to make sure that we have adequate supplies of treated salt.”
That treated salt, the public works boss explained, is sprayed with an organic sugar-based mash that helps make the application more effective, while balancing the soil pH to do less harm. Soil pH is a measure of the acidity and alkalinity in soils, and is important because it directly affects soil nutrient availability.
The US Environmental Protection Agency (EPA) does not regulate road salt but acknowledges that special consideration and best management practices are needed to protect reservoirs and other drinking water supplies near treated highways and salt storage sites from contamination with road salt runoff, said spokesperson Dale Kemery in a 2008 National Institutes of Health (NIH) report on the subject.
Besides its environmental effects, road salt also has functional drawbacks: it easily washes away and must be reapplied, and sodium chloride can melt snow and ice in temperatures only down to about 16°F. But when sugar is mixed with salt, the combination can address both drawbacks, making the salt stick better and allowing it to work at lower temperatures, thus reducing the total need for salt.
One such product, Ice B’Gone, combines magnesium chloride (a salt) with “distillers condensed solubles” (a sugar byproduct obtained from molasses factories). Salt companies blend it with rock salt. The advantage of using melting materials like Ice B’Gone is that it drops the minimum melting temperature to −45°F.
Although the treatment does raise the price of a ton of salt, it enables each ton to go further, netting a 25-40 percent reduction in road salt usage — a ratio that mirrors Newtown DPW’s experience. In addition, one manufacturer says the formula reduces the corrosive factor of salt by as much as 70 percent over regular road salt.
Sugar derived from sugar beets is the basis for another road salt additive called GeoMelt. Mixed with rock salt, GeoMelt lowers the melting temperature to −30°F, according to the NIH report, but some sources on the web report its gummy consistency plugs up and compromises salt/sand distribution mechanisms on trucks.
Sugars And Studies
In 2015, the potentially negative effects of salt compounds being used in Connecticut spurred debate and political interest. The Connecticut Mirror reported that while there were plenty of people who believed it was environmentally harmful, there was still plenty of disagreement over the cause.
As for what to do about corrosion, there were countless opinions with very little science yet to back up most of them — not to mention the mostly unknown environmental impacts.
The sugar products “might be better for corrosion; they’re not necessarily better for streams,” said Margaret Miner of Rivers Alliance, one of the only environmental groups in 2015 that was paying attention to issues related to snow removal. “The nutrients are just like pouring fertilizer in.”
She said as the sugars decompose and are consumed by bugs and bacteria, they gobble up oxygen, depleting it for everything else and causing problems like algae blooms.
“It can do harm for years or decades before people figure it out,” Ms Miner said. But, she quickly added, “We don’t want to be in a position that people should have terrible car accidents to save our streams.”
In 2017, UConn and its Center for Land Use Education and Research (CLEAR) representatives Michael Dietz, PhD, and Lukas McNaboe showed that anti-icing applications, including pretreating roadways with sodium chloride brine and/or prewetting rock salt with magnesium chloride measurably reduced winter season vehicle crashes in the state.
The Connecticut Academy of Science and Engineering (CASE), a private nonprofit corporation that advises the state on science and technology matters, conducted an earlier study for DOT. It noted that the state DOT’s increased reliance on calcium chloride and, more recently, magnesium chloride, stems from its 2006 switch from a strategy of treating roads with a mix of sand and road salt (“de-icing”) to one relying on prewetting of road salt (sodium chloride) and almost completely eliminating the use of sand (“anti-icing”).
In 2013-14, the report notes that DOT applied 227,511 tons of salt, and municipalities applied an estimated 483,000 tons, for an estimated total of 710,511 tons. Over the previous five years, the report found, DOT applied an annual average of 153,000 tons of salt.
Municipalities applied an annual average of 350,000 tons during that time, more than twice the amount DOT applied.
This total did not include the amount of salt private firms apply on shopping centers, parking lots, and sidewalks. CASE said it could not obtain these figures, but estimated that private applications for these purposes could be substantial, and that DOT’s use of de-icers may account for as little as nine percent of the total statewide chloride application per season.
Because of these findings, the report determined that winter maintenance, including appropriate de-icing chemical use, is something that the state, municipalities, and private entities, must share responsibility for — especially since there is little question that chloride de-icers affect water quality.
Ground Water Implications
The CASE report says that de-icing salts are a primary source of chloride in groundwater. According to the report, since the early 1900s average statewide well water chloride concentrations have increased tenfold, “and this increase has been spatially correlated with major roadways.”
High sodium levels may adversely affect people on low sodium diets because of kidney or heart disease or high blood pressure. According to the Department of Public Health (DPH) high levels of chloride often occur with elevated sodium levels.
Responding to DPH concerns about elevated sodium levels, DOT in the early 1990s changed its de-icing material to a special mixture of calcium chloride and sodium chloride. Since then, it has also implemented new best practices, such as calibrating spreaders, prewetting, and better controlling application rates.
In Newtown, DPW Director Hurley said each of the local trucks used for spreading salt has three mechanisms it can use to alter the amount and “throw” of the sand/salt mixture applied to local roads. He said the only places his crews use a higher concentration of salt versus sand is immediately outside of municipal buildings and schools, to minimize the amount of sand being tracked into the facilities.
Overall, Mr Hurley said the use of treated salt has allowed his department — like the state — to greatly reduce the amount of road sand being distributed and later reclaimed from gutters and catch basins for recycling.
“We’re still paying close attention to using the least amount of salt possible,” he said, adding that over the years, local front line crews have seen the best results from salt treated with organic sugar compounds.
“The guys say the treated brown salt we use is stickier and it doesn’t bounce off the roadside as quickly. That said, anyone who sees our spreaders will notice we tend to spread the salt mix closer to the middle of roadways,” he said.
Newtown has not yet adopted the practice of pretreating certain roadways and especially bridges with a brine solution, although Southbury has offered Newtown assistance in experimenting with the practice that has been in place in that neighboring community for several years.
Those who live and drive in Newtown, along with those who commute to and through the community should be confident that while the DPW is keeping a watchful eye on how much salt is being spread — there is still plenty of surplus to get the town through the rest of this winter.
“We did take an early delivery of sand and treated salt,” Mr Hurley said, “so our salt and our mixing sheds are still pretty full. We have plenty to get us through at least two or three more big storms before we’ll start looking at getting another delivery.”