The sewerage district in Wisconsin’s capital city aims to curtail salt for roads, sidewalks and water softeners to protect drinking water and the environment.
Salting roads is a way of life in Midwest winters. But all that salt has to go somewhere when the snow and ice melt.
And in an area where nearly every home has a water softener, a lot of salt ends up in local streams. While some salt in the drinking water supply is fine, too much can lead to environmental and health issues.
“The problem is, when too much salt is put down, it ends up in our waterways,” says Kathy Lake, an environmental specialist with the Madison (Wisconsin) Metropolitan Sewerage District. “We have a permit limit for chloride that is being exceeded. That’s why we’re trying to be proactive.”
Becoming salt wise
That’s why the district is teaming with several organizations to host training sessions that teach contractors and municipalities how to keep salt use in check. The district is part of the Wisconsin Salt Wise Partnership, a coalition of city and county agencies, educators and environmental groups promoting responsible salt use.
Road salt is inexpensive and so it is a cheap insurance policy against liability for accidents caused by slippery surfaces. A 2014 report from Public Health Madison & Dane County says more than 240,000 tons of salt were dumped on the city’s and county’s roads since 2010. That doesn’t count what was spread on county highways and private parking lots, sidewalks and driveways. Combined with the salt used in softeners, it’s too much. It’s concerning because for people with medical conditions such as high blood pressure, certain heart diseases, or kidney or liver diseases, sodium in water is a serious concern. High sodium levels can also harm plant life, and together with chloride, increase corrosion in pipes, pumps, hot-water heaters and fixtures.
“Because salt dissolves and we don’t see it, we haven’t paid a lot of attention to it, and there hasn’t been a lot of easy reference on what the right amount of salt is and when we should use it,” says Lake. “With Wisconsin Salt Wise, we’re trying to get that information out.”
The goal is to meet a standard chloride permit level of 395 mg/L. While the Madison area has seen a reduction in chloride, the level is still regularly in the 400 to 430 mg/L range. The district estimates that roughly 10 percent of its salt load comes from road salt.
“Just because the ice melts doesn’t mean it’s clean,” Lake says. “That salt is still around, but it’s dissolved in our lakes, streams and groundwater. So it’s really out of sight, out of mind. We’re trying to raise awareness year-round so that people know that salt is always going somewhere.”
While Lake says it’s sometimes hard to measure the effect of outreach to homeowners who spread salt on driveways and sidewalks, feedback from the district’s municipal applicator training sessions pointed to a common theme.
“There are many reasons applicators apply too much salt,” she explains. “That can happen when a public works department gets a call about a slippery road or someone falls on the sidewalk. The answer is typically to just throw more salt on it.”
That can be overkill, and the science often doesn’t back it up. Road salt is ineffective when the temperature drops below 15 degrees F, at which time municipalities could apply sand or other de-icers. However, most turn to salt because it is cheap. “We need to dispel the myth that more is better,” says Lake. “More salt is not better.”
Reaching the public
Salt reduction goes beyond training salt truck drivers. The campaign aims to educate the general public. It directs them to look at alternatives to salt and to show patience with public works crews who apply salt.
“We certainly want everyone to be safe, but if a public works department gets multiple calls on one corner, you can bet they are going to make sure it is taken care of,” says Lake. “That often leads to an over-application of salt. We teach them that there are other options, such as brine solutions and mechanical deicing equipment.”
Salt outreach doesn’t end when winter does. The district is working with softener manufacturers and suppliers on how to make home units operate more efficiently.
“We found through a study with softener suppliers that by replacing outdated softeners and optimizing newer ones, we can cut salt use by 27 percent,” says Lake. “We use rebates to encourage people to replace outdated softeners, and we work with service professionals to provide price breaks for optimizing systems. We’re seeing results.”
The district regularly plots chloride levels in its water supply, and the trend in recent years is downward. The district also commissioned a study on treating the hard source water at a treatment plant to eliminate the need for private softeners. Unfortunately, that would have cost about $400 million.
The utility has applied for a variance through 2020 to bring chloride levels within the limit, and Lake is confident the goal can be met. “It’s about being diligent in making sure people are informed,” she says. “We’re never going to get all the chloride out of our water, but there’s still room for improvement. We’re finding that room.”