There is a growing environmental concern in areas of the country where salt is used to melt snow and ice on roads and sidewalks.
Maintenance supervisors for roadways recognize the results from using salt and the problems they cause, and in recent years, have adopted methods to reduce salt runoff and ensure maintainable operating costs. Including Minnesota, in which 50 lakes have been listed as impaired due to the chloride, a byproduct of salt runoff when it dilutes.
Most of the impaired waters in Minnesota are located in the Twin Cities area. Due to the higher traffic volumes and expansive network of roads, the seven-county Minnesota Department of Transportation (MNDOT) district requires a higher use of salt.
Brooke Asleson, salt prevention program coordinator for the Minnesota Pollution Control Agency, claims that although most of the impairments are in the Twin Cities area, there are some impairments in Greater Minnesota in a couple of northern and southern areas of the state. She notes that the problem is not as significant due to lower traffic volumes and lower density of roads.
Although salt is the most cost-effective substance for melting snow and ice, it’s expensive. Many maintenance supervisors for streets and highways work to minimize the use or apply a sand-salt mix.
Kohl Skalin, a road maintenance supervisor for MNDOT out of the MNDOT Detroit Lakes district, said, “We’re trying to reduce salt usage on a continual basis.”
According to Asleson, salt is toxic to marine life and once it gets into the water through the storm system, the chloride becomes permanent and there isn’t any way of removing the pollutant.
In North Dakota, state agencies have not detected high levels of chloride beyond the water quality standards. The North Dakota Department of Health, which oversees the state’s water monitoring program and water quality observance, notes that sulfate is a more significant problem than chloride.
Sulfate is a naturally occurring salt found in the soil in places like northeast North Dakota and makes its way into water systems through seepage and natural runoff. Chloride from road salt, however, has not yet become a problem for the state’s waterways.
New technology has helped to reduce the amount of salt used and limit the amount of runoff, including automatic spreaders used by maintenance crews and public works agencies in Minnesota, North Dakota and the city of Fargo.
Sanding trucks in the city of Fargo are equipped with automatic spreaders that are calibrated to release 200 pounds of salt per lane-mile. The city also uses a sand-salt mix to prevent sand from clumping and chloride pollution, dispensing this mixture at 800 pounds per lane-mile.
According to Fargo Public Works, the city works to prevent sand and salt runoff, noting that the biggest problem is that salt doesn’t dilute until it gets warmer and sand needs to be swept up or runoff through the storm system. The city also does what it can to under apply salt or the sand-salt mixture, making sure their practices are economically feasible and eco-friendly.