Once road and de-icing salts wash into surface and ground water, there is no feasible way to remove the chloride, which means that chloride will continue to accumulate in the environment over time. More than 1 teaspoon of chloride per 5 gallons of water is toxic to fish, aquatic bugs and amphibians. When the road density in a watershed exceeds 18%, water quality problems are likely. In Minnesota there are over 40 surface waters that exceed the water quality standard for chloride and another 40 that are approaching the standard. 75% of Minnesotans rely on groundwater for drinking water. High amounts of salt in groundwater cause drinking water to taste salty, which could restrict its use for drinking, because the cost to remove salt from drinking water using reverse osmosis is expensive. Currently 30% of Twin Cities' drinking water wells have high levels of chloride. Chloride also corrodes road surfaces and bridges and damages reinforcing rods, increasing maintenance and repair costs. Deicing salt accelerates rusting, causing damage to vehicle parts such as brake linings, frames and bumpers.
See Chloride 101 (MPCA) for a summary of the issue, actions options and staff contacts to help your city take action.
Pervious concrete use in roadways both reduces stormwater infrastructure and salt use, with Shorewood as a national exemplar.
See model snow and ice management policies - for city-hired snow and ice management services, that mandate best practices to minimize environmental impacts from sand, chlorides and other chemicals - and for private snow/ice service contractors signing agreements with customers - developed in 2016 by snow and ice management professionals from cities and counties in diverse areas of Minnesota, watershed districts, the Minnesota Pollution Control Agency, the Minnesota Nursery and Landscape Association, and other stakeholders. These policies balance public interests including public safety, equipment and material cost, and environmental impact. See also a shorter model Snowplowing Policy from the League of MN Cities.
Partnering with others, the MPCA has created and offers a Smart Salting certification program, which has a section on gravel road maintenance and use of dust suppressants, and a web-based winter maintenance assessment tool to help winter maintenance organizations assess operations, identify opportunities to reduce salt use using proven BMPs, and to track progress, which always includes cost savings. The goal is to maintain performance while reducing salt use and saving cities money.
The biggest salt-reduction action, which is also the most effective way to prevent/melt ice and snow, is to apply liquid pre-wetting and anti-icing solutions to roads. These brines spread more evenly, stay put and begin working immediately because the salt/other components are already in solution. In Minnesota, cities that have switched to tanker trucks have reduced salt use by up to 70% and have paid back their equipment investment in a year or two.
Certify primary winter maintenance staff through the MPCA's Smart Salting Level 1 training (for city snowplowing, and for parking lots, service roads & sidewalks) and/or Property Management training; follow training recommendations; certify new staff and keep certifications current; actively promote a model contract that private snow/ice service contractors would sign with customers; report decreased use of CaCl dust suppressants and alternative dust measures. Note that this salt action was previously an erosion control action (replaced because erosion control is almost always required of cities).
Use efficient plows with brine tanks; certify the city at Smart Salting Level 2 by using the MPCA's winter maintenance tool to complete a best management practices assessment; redo assessment at least every 3 years; develop or adopt an existing chloride/salt management plan; modify and adopt a model contract for city-hired snow and ice management services that mandates best practices to minimize environmental impacts from sand, chlorides and other chemicals.
Report use of pervious concrete/paving and resulting salt-use reduction; complete two of: track salt usage; report salt reduction progress in the 30% to 70% range (over one year for 30%; over more years for 70%); track implementation of best management practices using the winter maintenance tool; educate residents about the environmental impacts of salt and provide information on how to reduce their personal salt use.
Who's doing it
Bloomington - 3 star
Date action report first entered:
Date of last report update:
Year action initially completed: 2019
Bloomington has certified primary winter maintenance staff through the MPCA's Smart Salting Level 1 training (for city snowplowing, and for parking lots, service roads & sidewalks), certifies new staff, and keeps certifications current. Bloomington uses efficient plows with brine tanks and has certified the city at Smart Salting Level 2, and has developed a chloride/salt management plan.
Bloomington currently tracks salt usage using a calibrated software on trucks, and has issued educational material to residents about the environmental impacts of salt on how to reduce their personal salt use.
The City's standards regarding erosion and sediment controls and requirements for permanent stormwater treatment are detailed in Title 10 (Water Resource Management) of the City Code.
The City has begun tracking the amount of salt used on city streets. 51 tons per event this years vs. 77 tons per event last year.
Additionally, the City has been working with a Green Corps member to educate residents regarding salt use. https://www.ci.rosemount.mn.us/718/Conserve-and-Preserve-blog---archive-1
Outcome measures/metrics/money saved:
The amount of salt used per event by the City's public works department was reduced from 77 tons last year to 51 tons this year. This reduction is reported to the City Council on a weekly basis during the snowy season.
Mounds View Operates three plow trucks during winter storm clearing operations. All three are equipped with 110 gallon brine tanks with one truck replaced in 2019 having a more efficient applicator along with a front, belly, and wing plow that removes more snow than trucks without the wing (front and belly only) further reducing the amount of salt/brine needed. In 2021 we will be replacing a second truck. The last truck is several more years out.
We also send our PW Director, Supervisor and any additional staff available to annual conference/seminar in managing/reducing salt during winter street clearing plow operations.
Outcome measures/metrics/money saved:
Reduction in chloride/salt onto roadways and eventually into storm/ground water
The City of Duluth faces many unique challenges when it comes to wintertime salt use. Frequent flushing of the surface water systems by snowmelt and rain events prevents chloride from building up to levels that impact aquatic flora and fauna, and concentrations in Lake Superior remain low regardless of how much is flushed simply because of the sheer volume of water the lake contains. This makes it hard to convince people that chloride use is a problem. However, test wells behind the mall near Miller Creek showed levels at 500mg/l providing a rare glimpse into just how much salt is being washed into the waterways.
Despite the challenges, Duluth is working to reduce chloride use. Pre-wet granular is used at all times to increase the effectiveness of the salt and reduce waste from bounce and scatter. Various combinations of salt and sand are used depending on temperature (current and predicted) and precipitation (type and volume). When it is too cold for salt to function plain sand is used. Plow truck guidelines require that salt be dispensed at 25mph or less to reduce bounce and scatter. The city does have one experimental liquid de-icing tank, however it requires a plow to be driven in front and is not frequently used.
Duluth's hills also present a challenge. 16% of roads have a grade of 6% or steeper, and safety concerns frequently lead to them being over salted. Fortunately the hill is South facing allowing the suns heat to activate salt at colder air temperatures. Emergency services from the growing Medical District rely on many of the steepest roads for transportation so keeping them clear is a high priority. Little research has been done on snow and ice control on such steep hills so there is little solid evidence to guide control plans. Consequently, most chloride reduction efforts are focused on the remaining 84% of roads that are not as steep.
Representatives attend the Annual Road Salt Symposium to learn about new technologies and techniques that may help reduce or more effectively apply material to the road surface.
In 2019 the City purchased a new piece of equipment that is estimated to reduce salt use by 30 percent per lane mile. The new piece of equipment is a precision applicator that can better target the areas where being applied.
Outcome measures/metrics/money saved:
The City anticipates that the use of this new equipment will reduce its salt usage by 30% per lane mile used. Preliminary results show the new piece of equipment is resulting in an overall reduction in salt being applied.