February starts to tease at spring, but also showcases the extent to which we’ve relied on salt to get us through the winter.
February is a tough month in Minnesota winter. I feel February is when we fully lose the magic of the winter season, and we can really see and understand everything we’ve had to do as a society to keep our daily lives moving in the previous three winter months. There are hardened piles of plowed snow in parking lots – darkened with soot and dirt – but what I notice more and more is the evidence of repeated and pervasive de-icing salt applications – the whitish residue on roads, parking lots, and sidewalks, and haphazard piles of blue-white or light pink salt crystals that our boots crunch and track into stores.
We really do have an ongoing love affair with de-icing salt – it is the go-to material helping us ‘keep ‘er moving’ during Minnesota winter. It’s estimated that just the Twin Cities metro uses over 345,000 tons of salt each winter season. It’s come to the point that those visible salt piles and satisfying boot crunches are an expected norm – people WANT to see the salt so they ‘know’ it’s safe. Many businesses and property owners understandably oversalt to avoid liability for slips and falls.
But needing that visual reassurance is contributing to some truly ugly consequences. Salt applied to roads, parking lots, and sidewalks wash into soil, lakes, and rivers, and even percolate to the groundwater (our primary drinking water source in Minnesota). Some distressing stats include:
- 40% of groundwater wells tested across the state are increasing have increasing chloride concentrations.
- 30% of sampled groundwater wells in the Twin Cities Metro exceed the chloride drinking water standard of 250 mg/L (the average ‘background’ groundwater concentration is less than 5 mg/L).
- Over 50 Minnesota lakes and rivers are currently listed as impaired for chloride, threatening aquatic life and ecosystems.
And saltier-tasting groundwater and harming ecosystems are just some of environmental and potential health impacts. Let’s also recognize that salt itself is a corrosive agent, and applying it repeatedly weakens infrastructure by corroding steel, reinforcing rods in concrete, and other materials. One study in Utah estimates that salt corrosion now costs the United States between $16-19 BILLION every year.
And here’s the real kicker: more salt does NOT equal more or faster melting. The general rule of thumb is that you need one coffee mug of salt for about 250 square feet (or 10 sidewalk squares). The crystals generally need to be spaced about 3 inches apart to do their job. The salt that is left over will simply dissolve in future snow melt or rain events, contributing more chloride to our landscapes. If you can see salt crystals on the ground AFTER the ice is gone, the surface was over-salted.
So what’s to do? Thankfully, there are some great initiatives already in place – the Minnesota Pollution Control Agency, partnering with Fortin Consulting, has put together a “Smart Salting” Training Program across Minnesota for the past several years. They offer virtual and in-person training workshops for city and county staff on smart salting methods for roads, parking lots and sidewalks, as well as a module just for property managers and public officials. Many times, these workshops are offered online for free. Individuals and organizations who complete the training become smart-salt certified for up to three years.
For the general public, the increased media coverage about chloride pollution is helping drive a lot of conversations, one of which includes promotion of the 5″R’s” of Smart Salting:
- Physical Removal: Before you salt, grab that shovel or snowblower and physically remove the snow before it has the chance to become ice.
- Right Conditions: Sodium chloride is less effective when pavement temperatures are below 15 degrees F. On super cold winter days (below zero), use sand for traction.
- Right Amount: As stated above, dispersing a coffee mug of salt over 10 sidewalk squares (or about 250 square feet), with about 3 inches between crystals, means you melt ice without having a bunch of salt left over.
- Right Product: Not all de-icing products are created equal – the purity of the salt will impact its efficiency and melting capacity. The higher the sodium chloride content, the more ice it will remove.
- Remove it: If you see salt after the ice has melted away, sweep it up and safe it for next time! Don’t let it dissolve and wash away!
It will take time to break the perception that more salt is better and ‘safer,’ but the faster we realize it, the better off our environment, public health, and infrastructure will be!