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Reductions in the use of deicing salt are possible through smart salt use and adoption of winter maintenance BMPs. Many winter maintenance organizations have already begun implementing salt reduction practices across the state. Examples of local efforts to implement smart salting strategies are included in this section to provide ideas that may work for other winter maintenance programs and to highlight the great work already being done.
Curt Pape presented this information at the 2012 Road Salt Symposium.
The Automated Vehicle Location (AVL) uses GPS equipment to track where and how much salt is applied. The Maintenance Decision Support System (MDSS) is used in conjunction with the AVL will use multiple factors to decide when, where, and how the salt should be applied. The average savings achieved through the use of the MDSS and AVL is 53 percent.
Over 11 ice and snow events, a total of 71,745 tons of salt was applied at a total cost of $4,356,351. Using the projected average savings from implementing MDSS and AVL of 53 percent, the total savings would be approximately $2,308,866, which would also prevent over 38,000 tons of salt from entering lakes, streams, wetlands, and groundwater.
This information was taken from the Dakota County Smart Salting training KAP Study Report (Eckman et al. 2011).
The snowplow drivers in Dakota County, Minnesota, attended the MPCA sponsored Smart Salting training course presented by Fortin Consulting and the Minnesota LTAP in 2008. To test the effectiveness and impact of the course, a knowledge, attitudes and practices (KAP) was administered to these drivers before the course to establish how the snowplow drivers approached the job. After two winter seasons, approximately 14 months after the initial training, the same KAP test was administered again to measure any change. Steps were taken to maintain confidentiality of the respondent and to insure the same people were compared. Seasonal and temporary employees were not used in the comparison.
In September 2008, the results of the survey showed that Dakota County plow drivers had good general knowledge and good practices, but they were in need of some improvement. While the drivers were aware of the county’s winter maintenance policy, the independent judgement factor was a little more difficult. For example, only 60% agreed they “minimize the use of deicers during a snow storm.” Although this type of information is useful, the goal was to evaluate how effective the training was to actually make a difference in all three facets of knowledge, attitudes, and practice.
The follow up survey in November 2010 showed mixed results. Most importantly, some of the significant improvements were under knowledge and practices.
Dakota County plow driver survey
Link to this table
|Question||2008 Response (Yes)||2010 Response (Yes)||+/- percentage change|
|I minimize the use of deicers during a snow storm||60%||96%||+36%|
|During calibration I have set the computer speedometer to match my trucks speedometer.||40%||73%||+33%|
|I use an application rate chart to determine the amount of salt/sand to apply||35%||76%||+41%|
|I avoid using road salt when pavement temperature is below 15 degrees F||27%||88%||+60%|
|I document my winter maintenance actions||73%||69%||-4%|
|The policy encourages plowing before two inches of snow accumulation||92%||84%||-8%|
|Equipment is calibrated for each type of deicing material used||92%||88%||-4%|
|I have ground-speed controlled sanders-the auger is installed and working||84%||77%||-7%|
|I plow before applying deicers to minimize the dilution of the chemical||96%||92%||-4%|
|I avoid salt/sand mixes||72%||68%||-4%|
The areas that showed declines were areas that either additional training or clearer policies could produce better outcomes. The majority of the questions indicate there has been a positive shift in knowledge, attitudes, and practices since attending training. In addition to the KAP survey, the amount of actual salt has been reduced to further underscore the success of the training. The county used an average of 405 tons of salt per snow event in 2007, the winter season before attending the training. Post training, the county reduced their usage by about 50 tons per event to 355 tons of salt per snow event. This reduction correlates to about 40 million gallons of freshwater protected from chloride contamination per snow event.
This information was supplied by Scott County.
The past practice of Scott County was to use a mixture of 1:1 sand and salt that was applied with uncalibrated spreaders. No policy or guidelines were in place for mixture ratios or spread rates.
The county started a training program for the supervisors and operators to familiarize them with the effectiveness of salt depending on pavement and air temperatures. After attending the training, treated salt was added to the county’s material options. Each plow truck was supplied with information about the route, how many lane miles, and tables for each material and its spread rate based on the temperature.
It took several events to convince the members of the team of the effectiveness. There was not an instant buy-in from the drivers, but after several events, most of the drivers were impressed with the results using the treated salt. During the course of 8 to 10 events, the usage of the sand and salt declined. The winter maintenance teams stopped using the sand/salt mixture, although small cities and townships continued to purchase the sand/salt mixture from Scott County.
By implementing the new practices and policies, the drivers found a single load, or less, was enough to treat the route. Anecdotally, the drivers reported the usual practice would be to apply three or four truckloads of the sand/salt mixture in a single event. The County estimates that 1,500 to 2,000 pounds of the sand/salt mixture was applied per mile lane each event. After the change, the usage dropped to about 424 pounds per lane mile per event. The savings of over 1,000 pounds per lane mile paid for the increased costs of the treated salt. This correlates to a 25-30% reduction of chloride entering lakes, streams, wetlands, and groundwater. Scott County maintenance believes this is the most economical and environmentally sound approach available.
St. Louis County began working on reducing salt contamination by erecting dome buildings and coverall type buildings where they store their salt and sand. This has been accomplished by the county alone and through partnerships with Net Lake Indian Reservations, Hibbing, Ely, and the state. They now have all of their salt and sand supplies covered. Hibbing, Pike Lake, and Ely have built-in storm water drainage ponds to stop runoff into lakes and streams.
In 2008, trucks with calibration technologies were purchased to make the application of materials more precise. They will continue to purchase trucks with this technology. In addition to this technology, the newest trucks in the fleet have pre-wetting equipment and GPS/AVL technology. Forty-six trucks purchased prior to 2008 have been retrofitted with the calibrated controls and pre-wetting equipment. Plans to add the GPS/AVL have been made, depending on available funds. St. Louis County has expanded their salt brine making capabilities to five additional facilities by partnering with MnDOT to share capabilities in Hibbing and Pike Lake.
St. Louis County currently uses approximately 19,265 tons of salt each year and 67,440 cubic yards of sand, at a cost of around 1,207,338 and 202,320 dollars respectively. Through the addition of new equipment and implementation of better practices, St. Louis County projects they will reduce their salt use by as much as 45%. The projected monetary savings is 634,346 dollars per year. The environmental savings is the prevention of 8,669 tons of salt from entering the environment, and saving 7 billion gallons of freshwater. By reducing the application of the less effective sand/salt mixture, St. Louis County will be responsible for reducing 30,348 cubic yards of sand from entering the rivers and streams.
Cottage Grove saw a significant decline in salt usage after attending training. Their usages for the past few years, per event have declined steadily.
The City realized a savings of 694 tons of salt for the 2011-2012 winter season. This translates into a savings of 40,000 dollars in one season.
This information was gathered from Tom Struve’s presentation notes, 2011.
The city of Eagan discontinued mixing sand and salt in the 2005-2006 winter season. Without dropping the level of service to residents, the city was able to eliminate a five year average purchase of safety grit. The elimination of the 3,249 tons of grit led to a 65% reduction in spring street sweeping hours. This elimination saved Eagan 70,000 dollars per year.
In 2008, Eagan began using EPOKE winter chemical application technology. This enabled the city to use a precise chemical application of up to 90 gallons of brine per one ton of salt and realize immediate improvements. Also, the addition of AVL allows snowplow drivers to inform the police of the location of cars remaining on the streets during snow emergencies. The police receive a map by 8:00AM showing the exact location of the cars, which makes the mechanical removal of snow much more efficient and effective for the snowplow drivers.
The city of Eagan implemented additional practices including: pre-wetting material at the spinner; using salt brine to 10-15 degrees and substituting magnesium chloride when the temperature falls below 10 degrees; limited uses of Clear Lane for severely cold temperatures; and, managers directing the lane mile calibrated application rates. Eagan still has a stockpile of sand, which they rarely apply. Most importantly, Eagan has the buy-in of the operations staff, which has been very important for their success.
Despite the new practices, the level of service that Eagan provides for residents remains high. The residents have high expectations for winter road maintenance and Eagan has been able to make changes to reduce salt use, while also meeting the expectations of the community.
The winter maintenance operators and managers for the city of Minnetonka are committed to the need to reduce salt to protect the environment. This city delivers high service and the residents expect excellent service. Minnetonka Public Works maintains 254 centerline miles of streets which includes 562 cul-de-sacs. During full scale snow events of 2 inches or greater, 20 plow trucks, 2 loaders, and 7 pickups are mobilized to perform snow removal.
Prior to the 2010-2011 winter season, Minnetonka installed a Cargill Accubrine automated brine production system. The system can blend up to two other products with the brine produced to aid in temperature suppression of the brine when needed. There are five 6,500 - gallon tanks to store the finished products or purchased additives. The City currently uses a corrosion inhibited 32% calcium chloride to pre-wet salt when temperatures are below 15 degrees F. Outside agencies, including Hennepin County and neighboring cities, purchase brine for use. The brine is used to pre-wet the salt before it is applied to the road and for anti-icing prior to a snow event.
Prior to snow events, Minnetonka uses a 2,000 gallon tanker truck and a truck with a 900 gallon tank that are used to pretreat the highest volume streets with brine at a rate of 30-35 gallons per lane mile. The fleet is currently being retrofitted with new technology: pre-wetting equipment, on spot chains, Force America data, and AVL.
All 20 plow trucks and 1 spare truck in the snow fleet are equipped with ground speed controllers to accurately apply and track salt used. The trucks are also equipped with brine tanks so that the salt that is discharged from the trucks is treated with brine at a rate of 10 gallons per ton of salt.
The City subscribes to a web-based weather service that provides a 48-hour weather forecast which is updated every hour. Information provided includes air and pavement temperature, wind speed, dew point, snow and ice accumulation totals and rates/hour, when the precipitation will start and stop, and also provides recommendations for salt and liquid application rates. This information supports decisions for properly staffed crews for the event, application of anti-icing liquid, and the application of the correct liquid for pre-wetting the salt. City staff can compare information from around the state with regards to road temperatures, wind speed, and radar to see how an approaching storm will affect Minnetonka operations.
The AVL is used on all mobile snow equipment to track vehicle location and salt application. A real-time, citywide map shows progress of snow removal operations and allows movement of plows around the City to address any missed areas or areas that are running behind schedule. The system will also send an email notification if an error occurs with a salt controller on a truck. Depending on the status of the plowing and storm, staff determines whether to bring the truck in for repair. Even if in an error state, the controller is able to track salt application provided the spreader is functioning. Four trucks are equipped with air and road temperature sensors which are monitored through the AVL system.
The city of Minnetonka has achieved its goal set by the Nine Mile Creek Watershed during the 2010-2011 season. They reduced application of salt to 4.2 tons per mile from 7.022 tons per mile. This was a reduction of 180% during a normal season.
Minnetonka is focused on improving the use of liquids. For the 2012-2013 winter season, the trucks averaged 3.5 gallons/ton of brine for pre-wet and the city realized that the nozzles were not calibrated for the gravity application system. The nozzles are now calibrated along with the salt controllers before winter and the average for 2014-2015 increased to 6.2 gallons/ton. This is still below the 10 gallons/ton rate the trucks are calibrated for but it is improving.
This information was provided by Freshwater Society, 2014 Environmental Leadership Award on February 6, 2014.
In 2009, Norwood Young America city employee’s attended an ice and snow workshop where they learned the importance of calibrating equipment. In 2010 staff attended another workshop on snow and ice control practices. After training, the city purchased tanks for pre-wetting salt. Through the implementation of recommended practices and attending the Smart Salting training, the city was able to reduce their salt usage by almost half in 2010. On average, the city had been using about 600 tons of salt per year.
After training, the city averaged 350 tons per year, saving 17,500. This success has encouraged the city to continue to improve their operations and practices.
The city of Plymouth began implementing salt reduction practices in 1996 by implementing the use of brine. At first, brine was used on a limited basis, but expanded through 2004. The city began implementing anti-icing and expanded its application by purchasing a 1,300 gallon tank in 2007. The AVL technology was added to the vehicles in 2009 to track the routes and salt application. The city continues to improve, and in 2014 purchased its most recent 1,300 gallon brine tank for anti-icing.
As with many municipalities, it is difficult to track the reductions with absolute certainty. The City has experienced growth in excess of 30% since the mid-nineties. Granular salt use has been decreased by 40% despite this growth. Despite the 40% reduction in granular salt, it should be noted that there is still salt applied in the form of brine for anti-icing. The City estimates that the overall reduction, since the mid-1990s, is approximately 25%
The information provided below is based on information provided by the city of Prior Lake for the 2010 American Public Works Association Excellence in Snow and Ice Control awards ceremony. The city of Prior Lake maintains approximately 100 center lane miles of street with 10 maintenance personnel and one supervisor. Starting in 2003, Prior Lake implemented a winter maintenance program which includes:
The staff buy-in and support was critical to the success of this program. Education was important for this; they started with supervisor training and researched other programs. Various training programs were attended or used including: LTAP, CTAP, Manual of Practice for an Effective Anti-icing Program, APWA Anti-icing/RWIS CD, AASHTO Clear Roads CD Series, and attending an APWA Snow Conference.
Since 2003 to 2011, the City invested about $250,000 in the program, including a $50,000 building addition. They recognized that the right equipment is the key to providing the flexibility to apply the right chemicals, in the appropriate amounts by the most efficient method.
Depending on conditions, Prior Lake keeps pre-mixed chemicals ready for use and bulk materials on hand. This allows the City to pre-mix and modify operations depending on weather conditions. Using the best available weather data for preparation and monitoring actual ground temperatures during operations is critical.
Equipment upgrades can be phased in over time. Prior Lake took seven years to fully upgrade the fleet. The new 5100/6100 controllers and new sanders can apply pre-wet material at rates down to 85 pounds per lane mile. Liquid application units can also apply at below 100 pounds per lane mile rates. Upgraded equipment includes:
Liquid anti-icing operations increased removal efficiency. The City found that applications are effective for 7-14 days after application, depending on the type of mixture and conditions. Equipment was also used for a liquid-only route with deicing application rates of less than 100 pounds per lane mile.
Efficient truck design and equipment including Elliptical Box, 200 gallons of Liquid Storage, Falls Salt Special Material Applicator, Force America 6100 Controller, and bed tarp allows for more efficiency with application rates of pre-wet salt as low as 85 pounds per lane mile.
Prior Lake had a reduction of average application rates from 500 pounds per lane mile of salt in 2005 lane to 200-250 pounds per lane mile using pre-wet salt in 2010.
This information was taken from the Six Cities Chloride Reduction Project.
The city of Centerville, after attending a winter maintenance workshop, collaborated with Lino Lakes, Hugo, Circle Pines, Lexington, and Columbus to purchase shared anti-icing equipment and to train the staff to use BMPs. The coalition was able to successfully apply for a Rice Creek County Watershed grant of 65,000 dollars to offset the costs. The new anti-icing equipment was used to apply liquid salt brine to 245 miles of paved roadways before the winter storms to reduce the need to apply salt during and after the storm. The training provided to the operators, reinforced the need to apply enough salt for public safety, but to avoid applying unnecessary amounts to pollute. The coalition plans on using the savings on materials to continue to fund the operational costs and program maintenance.
In the 2012-2013 winter season, the six participating cities reduced their salt use by 528 tons, or a 32% reduction based on the previous monitoring data. The six cities saved a combined total of $26,400 in a single winter, based on a conservative cost estimate of $50/ton of salt.
The information provided below is based on information presented at the awards ceremony at the 2013 Road Salt Symposium (Freshwater Society 2013).
In 2009, the Nine Mile Creek Watershed District (NMCWD) began a TMDL Analysis and Report process for the chloride impairment identified for the Nine Mile Creek. By 2010, they had prepared a draft TMDL report that called for a 62% reduction of salt application by the NMCWD MS4 cities, including Richfield. Along with other agencies, Richfield’s reaction to the reduction was the requirement was not only unreasonable, but impossible. They believed that public safety would be compromised and that the goal was too far to take seriously. However, the City eventually came to accept that they had to make efforts toward reducing salt usage.
The City Engineer learned that the NMCWD was working with Fortin Consulting and the LTAP to offer the free MPCA Winter Maintenance Certification Training. After attending the training the City Engineer found the training to be excellent. The entire snowplow operations staff was immediately enrolled in the next available training and all of the snowplow operators that plow parking lots have attended the MPCA Winter Parking Lot and Sidewalk Maintenance Training.
Despite the pride and effort that Richfield’s winter maintenance staff has in their work, the training showed them many ways to improve their operations. The education, along with the dedication of the staff, created a sense of urgency to change their practices and make the needed improvements. The changes needed were relatively small and simple to implement quickly
Richfield’s salt application process changes were:
These small changes reduced the amount of salt applied to roads by over 50%. It is projected this will improve over time, bringing the city closer to the TMDL of 62%. The Richfield operators have traditionally taken great pride in their work; the additional training provided them with the understanding of the importance of reducing salt for the environment and not just cost savings shown below.
1 The cost savings were based on the 2009-2010 price of salt.
This information was supplied from the city of Shoreview in 2015.
In 2006, the city of Shoreview stopped using a mixture of sand and salt and began using straight salt. This was the beginning of a continuous effort to reduce chloride.
Shoreview’s applicators and their supervisors each attend the annual “Snow and Ice Control Best Practices” training and are certified through the MPCA. The crew attends an annual meeting to discuss and review procedures and conservation methods. The operators are trained and allowed to make adjustments based on conditions and the pavement temperatures. The MPCA materials, guidelines, and BMPs have been successfully used throughout this effort.
A snow event begins with the city’s crew monitoring the surface temperature and road conditions. This information is critical to following their BMPs and application guidelines. This practice allows for preparation for the storm and the application of anti-icing to reduce the ice that requires treatment during and after the storm.
The goal of the anti-icing procedure is to apply calcium chloride to at least 28 lane miles of roadway before the storm to reduce the buildup of ice and allow for cleaner plowing. All of the city’s trucks are equipped with state-of-the-art spreading controls, pre-wetting tanks, and pavement sensors to ensure that each truck is calibrated and efficient. The use of the pre-wetting calcium chloride reduces the need for rock salt and minimizes the loss of salt from bounce or vehicle distribution. Pre-wetting allows the salt to be effective at lower temperatures.
The three-year average salt use for 2006-2008 was 786 tons and in the period of 2009-2011 the average amount of salt used dropped to 437 tons. The reduction continued during 2012-2014 to 444 tons. Although the tons of salt appear to increase, there were more snow and ice events during the 2012-2014 period. The total reduction of salt since 2006 is approximately 44%. The cost savings for 2014 is estimated at approximately 24,468 dollars.
This information was provided by Freshwater Society, 2014 Environmental Leadership Award on February 6, 2014.
St. Paul Street Maintenance has changed and updated its snow maintenance practices and equipment to reduce salt, increase driver safety and improve the service level. The city created its first Snow Plan in 2011 through the collaboration of the maintenance staff.
The following equipment has been upgraded:
Between 2012-2013, the following training was completed:
The city has had an average salt reduction of 30% per event over the past five years. The purchase of salt was reduced over the five years from 24,000 tons to 16,000 tons.
The information provided below is based on information presented at the awards ceremony at the 2013 Road Salt Symposium (Freshwater Society 2013).
The city of Waconia Public Services Department completes winter maintenance activities on 56 street center lane miles, portions of 14 miles of concrete sidewalk and 13 miles of bituminous trails.
Prior to the winter season, City staff attends an annual winter preparations meeting. They review the Winter Maintenance Policy, route assignments; discuss material use, and the service level expectations. All spreaders are calibrated for liquid and solid material applications. Calibration charts are prepared and placed in each vehicle for user review.
In 2010, the staff updated their 1999 “Snow and Ice Policy” to a “Winter Maintenance Policy.” The document title expresses a different, proactive approach to events. In the past, the city had a reactive approach to storms. The City changed from a 1:1 sand/salt mixture to straight salt and liquid anti-icing practices. Additional items reflected in the policy included:
By implementing calibration and equipment changes, the staff has been able to reduce materials rates of salt per-pound by 70%. Using pre-wetting practices and saving material by application rates based on weather and pavement conditions have saved 1.80 dollarsper-lane-mile and a yearly savings of 8,600 dollars.
As part of the winter maintenance practices for sidewalks and trails, the staff took the initiative to switch from hand-applied and truck-applied chloride products to liquid applications only. The staff conducts anti-icing and deicing activities as needed on sidewalks and trails leading to substantial savings. The staff obtained a “Local Operational Research Assistance Program” grant for 5,000 dollars. The research found a savings of 70% for activities related to recreational critical areas through the use of liquids for trails and sidewalks
The information provided below is based on information presented at the awards ceremony at the 2007 Road Salt Symposium (Freshwater Society 2007) and updated by Doug Lauer, a Landcare Supervisor with the University. The UMN Twin Cities Campus made changes to their winter maintenance program starting the winter of 2006. They began making their own salt brine and anti-icing and adopted several other salt reduction BMPs. The resulting reductions for each winter maintenance material are listed below in Table 10.
Twin Cities Campus – Winter Maintenance Improvements
Link to this table
|Material||Tons/Year Used (1997-2005)||Tons/Year Used (2006-2008)||Tons/Year Used (2008-2014)||Reduction||Notes|
|Ice Melt (MgCl2)||131||64||51%||Changed from MgCl2 to CaCl2 in 2008|
|Ice Melt (CaCl2)||131 (MgCl2)||59||55%|
In addition to salt reductions, they invested about 10,000 dollars in new and saved 55,000 dollarsthe first year the BMPs were implemented. The UMN used an average of 1,965 tons of sand from 1997-2005; in 2006 to 2008, it was reduced to 18 tons. This is a 99% reduction. Between 2009 and 2014, the UMN used an average of 21 tons of sand in this five year period, showing a continuing decline.
The UMN continues to use brine to treat before the storm, as indicated in Table 10. The staff is aggressive with mechanical removal using blades and brooms. A change was made from magnesium chloride to calcium chloride because it mixes better with sodium and doesn’t clog their equipment when changing products. The product contains less corrosive beet juice.
Joe’s Lawn and Snow is a small lawn and winter maintenance company located in the TCMA. The following information was provided by Joe Mather, owner.
Joe’s Lawn and Snow plows and treats both sidewalks and parking lots. Prior to attending the MPCA Winter Maintenance Certification class, the staff relied on manufacturer recommended application rates and best judgment for application rates. Joe Mather attended the certification class in the winter of 2013-2014 and sent four employees. Joe and his staff were able to implement the practices learned in the first year.
Practices implemented included:
These changes, implemented for the last half of the 2013-2014 season, resulted in a reduction of salt by about 50% and did not reduce the level of service. Based on the 2014 cost of salt per ton, this saved Joe’s Lawn and Snow 770 dollars in material costs.