Sensible salting practices can reduce environmental impacts from salting operations and save your community. Simple changes in the amount and ways we salt can make a big difference.
Environmental Impacts – Road salt (sodium chloride) negatively impacts our soil, water, vegetation, and wildlife. It can destroy soil stability and decrease the soil’s ability to store water. Road salt also increases soil erosion. In some cases, it can even cause the soil to release nutrients back into the water. One teaspoon of road salt can permanently pollute five gallons of water. Chlorine is not easily filtered out of water by water quality practices or the natural environment, and it is instead transferred to soil or ground water tables. Our ground water already holds high concentrations of chlorine. Ground water tables serve as a source of water for streams during dry periods, which means all of this chlorine can eventually end up in our streams. High levels of chlorine in our streams are toxic to fish and insects, and low levels can reduce fish and insect reproduction and survival rates. In addition, the direct road splash during salting operations can kill grass and plants.
Economic Impacts – In 2007, 18.3 million metric tons of salt were sold. The annual deicing costs for the United States are estimated to be around $2.3 billion. Yet road salt costs communities a lot more money than just purchasing costs. Corrosive to bridges, buildings, vehicles, and infrastructure, road salt increases the maintenance costs of these structures by billions of dollars. Road salt also threatens drinking water supplies, especially in well-water areas. It has high disposal costs.
Compliance Impacts – The US Environmental Protection Agency (EPA) Water Quality Criteria states that chloride levels at or above 230 mg/l for over four days are harmful to aquatic life. High levels of chloride in ground water create streams with high levels in fall when the streams rely on ground water as a source of water during the dry period. These elevated fall concentrations make it easier to raise concentrations to toxic levels in winter. It is estimated that sites with 50-100% urban land cover exceed chloride water quality criteria 100-200 days a year. Water quality impairments are likely to occur when at least 15% of the watershed is dedicated to urban development and transportation uses and/or salt loading rates are approximately 70 metric tons per square kilometer. In the Tinker’s Creek watershed, urban or impervious cover ranges from 6.16% in the south to 43.7% in the north.
Implementing sensible salting practices involves: alternatives to traditional road salt, salt storage best management practices (BMPs), snow disposal BMPs, salt application BMPs, education and outreach, and creation of a community-wide Sensible Salt Program.
Alternatives to Traditional Road Salt – Traditional road salt is sodium chloride, which, while relatively inexpensive, causes all of the negative impacts discussed above. The cost per ton, lowest operational temperature, advantages, and disadvantages to each alternative investigated are outlined in the table below. Some alternatives require less frequent application, lowering their overall use cost. For example, calcium chloride and magnesium chloride both require less frequent application than sodium chloride. Thus, the cost per lane of these three compounds is very similar. Communities should consider materials cost, clean-up costs, and maintenance costs to choose the most cost-effective deicer for them.
|Compound Name:||Cost (per ton):||Lowest Operational Temperature||Advantages:||Disadvantages:|
|Sodium Chloride||$35||15ºF||Low cost||Environmental, economic, and compliance impacts|
|Calcium Chloride||$290 for flakes
$340 for pellets
|-25ºF||Requires less frequent use||Contains chlorine|
|Magnesium Chloride||$260 for flakes
$300 for pellets
|5ºF||Least toxic deicer||Causes tracking and discoloration|
|Urea (Fertilizer)||$280||20-25ºF||Less corrosive||Inputs excess nutrients|
|Calcium Magnesium Acetate||$2,000||22-25ºF||Less toxic||High cost|
|Sand||$15||No melting capacity||Provides traction||Source of sediment pollution|
Salt Storage – Salt storage BMPs address NPDES Permit Part III.B.6.d.iii.2 and the following Total Maximum Daily Load (TMDL) pollutants: total suspended solids (TSS), nutrients, habitat, dissolved oxygen (DO), bacteria, and flow. Because salts are so soluble in water, they pose a major threat to our stormwater. Therefore, salt should always be stored in a closed area like a salt dome. Street sweeping and materials handling BMPs should be implemented as well to further to reduce chances of pollution.
Snow Disposal – Snow disposal BMPs address NPDES Permit Part III.B.6.d.iii.2 and the following TMDL pollutants: TSS, nutrients, habitat, DO, bacteria, and flow. Snow that is plowed from the roads contains many pollutants, including road salt, and therefore, snow disposal areas must be chosen to minimize the spread of these pollutants to stormwater and surrounding water bodies. Snow disposal areas should be near wide vegetated buffers or berms. Vegetation and snow fences next to roadways prevent snow from coming onto the roads, reducing the amount of snowfall requiring disposal. Some communities also reuse water from snow melt to produce brine. Brine can be used to pre-wet granular salt to reduce the amount of deicers ending up in shoulders or roadside ditches, or brine can be applied directly to roads in combination with salt.
Salt Application – Salt application BMPs address NPDES Permit Part III.B.6.d.iii.2 and the following TMDL pollutants: TSS, nutrients, habitat, DO, bacteria, and flow. Using a combination of road salt and alternative deicers often proves the most cost-effective for communities. New technologies for salt trucks like temperature sensors, computerized salt spreaders, and GPS systems reduce over-application rates. Reducing over-application saves money for communities and helps maintain a clean environment. Salt application can be reduced by prioritizing streets in much the same way communities prioritize for street cleaning. Focus deicing efforts on hills, curves, and intersections. Municipal staff and private contractors should be trained on proper application procedures.
Sensible Salt Program – The Sensible Salt Program was developed by the Cuyahoga County Service Directors Association to reduce salt usage by 30% and keep the environment cleaner. Under this program, communities will limit salting on secondary roads; limit overnight salting; focus application at hills, intersections, curves, and bridges; and implement spot salting, or salting at 150 ft intervals on main roads. This program was adopted by the City of South Euclid in 2008. Click here to view South Euclid’s Sensible Salt Program.
Sensible Salt Programs require an education and outreach component to ensure citizens are aware of the changes and understand their safety is not being jeopardized. Providing citizens with information about your program and tips for sensible salting at their own home can help reduce salt pollution in your community. Click here to view Sensible Salting: Tips at home.
Tinker’s Creek Watershed Partners would be happy to help create a Sensible Salting Program for your community. Contact TCWP for assistance as well as a Sensible Salting Program checklist, a template for Pollution Prevention and Good Housekeeping Programs, Pollution Prevention and Good Housekeeping Program Guide, and more information on individual BMPs and incentives.
Tinker’s Creek Watershed Coordinator