You paid for every pound that goes into the spreader. A lot of dry salt never stays where it landed.
Bounce and scatter
Michigan DOT studies, replicated many times since, found that about 30% of dry salt ended up off the road, compared with roughly 4% when the salt was pre-wetted.1 In another Michigan test, 80% of pre-wetted salt was still on the pavement after 100 vehicles had passed at 38 mph, compared with only 15% of dry salt.1 Lots are slower than highways, but the physics is the same. Dry granules bounce off hard, frozen pavement and get thrown by tires, spinners and plows.
Ways to cut the waste
- Pre-wet at the spinner, or buy treated salt.1
- Lower the spinner speed and narrow the pattern. Don't throw salt onto turf and into the street.
- Plow first. Salt on top of 2 inches of snow is being spent melting snow you could have pushed.
- Sweep up leftover salt on dry pavement after the event and reuse it.
Refreeze: the 2 a.m. call
Refreeze happens when brine on the pavement gets diluted past its working point, or meltwater runs into colder spots, and then the pavement temperature drops. Common Iowa setups:
- Sunny afternoon, clear night. Snow piles melt across the lot in the sun and refreeze as sheets after sunset, when clear skies pull pavement temperatures down fast.
- Diluted brine. Heavy snowfall keeps watering down the brine until it freezes again. Re-apply or plow before you're working against slush.
- Pile drainage. Snow piles placed uphill of walks, drains or entrances feed water across them every melt cycle. Stack downhill and away from foot traffic.
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