By Kevin Westerling,
A monster called "Jonas" visited the East Coast in late January, bringing record snowfalls and a death toll that stands at 48 as I write this. It goes without saying that safety is of primary concern during and after such winter storms, and an important part of the effort is the application of sodium chloride — road salt, rock salt, ice melt, etc. — to reduce slippery conditions on roads, parking lots, and sidewalks. But there is a downside to the liberal application of road salt: it eventually ends up in waterways and groundwater, affecting ecosystems and water quality.
The New Hampshire Department of Environmental Services (DES) did a study on the effects of road salt, finding, in summary, that "The accumulation and persistence of chloride poses a risk to the water quality and the plants, animals, and humans who depend upon it." Detailed repercussions are provided here, but some notable occurrences include:
- Drinking water taste-and-odor issues arising from chloride levels above the U.S. EPA secondary (voluntary) standard of 250 mg/L;
- Watersheds that are unable to sustain aquatic life due to sodium chloride levels as high as 800 mg/L, resulting in stratification and oxygen depletion;
- Vegetation degraded by salt damage, limiting the ability to uptake nutrients and pollutants; and
- Soil that becomes depleted and impervious, thereby decreasing fertility and water infiltration.
Separate from the New Hampshire DES study, another notable effect of chloride is the corrosion of pipes. According to Popular Science, a key factor in the Flint water crisis was the Flint River's chloride concentration, making it 19 times more corrosive than the Detroit River, Flint's previous source. The article cites Virginia Tech's Marc Edwards, a researcher conducting water tests in Flint, who further assigns blame to road salt specifically:
"[Corrosion] is an emerging problem for cities ... most likely due to increasing use of road salt. In portions of the northern U.S., chloride concentration in streams approximately doubled from 1990 to 2011."
Besides these numerous negative impacts for water managers, road salt is also dangerous to birds and mammals that ingest it, and even to household cats and dogs from licking salty paws.
As New Hampshire witnessed yearly trends toward increased road salt application and more chloride-impaired waterbodies — 47 listed in the state’s 2014 water quality assessment report — they decided to do something about it. The result is a program called Green SnowPro, a training course for municipal staff and commercial salt applicators to learn best practices for providing safe conditions while laying as little road salt as possible. Tactics include equipment calibration, pre-wetting surfaces with brine, and adjusting the rate of application based on pavement temperature. Certification requires four to five hours of classroom learning combined with field demonstration of techniques, followed by a half-hour exam. Every two years, a two-hour refresher is required to maintain certification.
According to the EPA, which highlighted the program in Nonpoint Source News-Notes (January 2016, #99), about 500 certifications have already been issued in New Hampshire, with 50 to 70 more expected this year.
Why so popular? It’s likely because the program appropriately addresses four important concerns: environmental impact, cost savings, public safety, and (the biggie) liability. You wouldn’t be alone if your first thought on reading this idea was “less salt = more lawsuits.”
The New Hampshire DES saw this coming. According to EPA: “Under the new law [the Voluntary Salt Applicator Certification and Liability Protection Program, established in 2013], certified commercial salt applicators and property owners who hire certified applicators are not liable for damages arising from snow or ice (e.g., slip-and-fall incidents), provided the commercial salt applicator uses best management practices and keeps proper records.” Such freedom from liability counters the natural worry of litigation, especially when “more is better” is an ingrained mindset.
While that liability benefit is aimed at commercial entities, gains in efficiency and water quality are significant drivers from a municipal perspective. The New Hampshire program includes an online accounting component to track salt use through the years, with the hope that declining usage rates will coincide with improved water quality assessment reports and less overall environmental impact.
With interest already proven and measurable results pending, Green SnowPro could serve as a model for other states and communities to adopt a similar program. There’s little doubt that other municipalities will run into the same salty issues experienced in New Hampshire (and even Flint) if over-application trends continue, so watching for symptoms and starting a plan to cut back is advisable. Once the salt finally clears, the myth of “more is better” is exposed.