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+ | {{alert|We are in the process of migrating the Winter Parking Lot and Sidewalk Maintenance manual to the Minnesota Stormwater Manual. You can access a pdf version of the maintenance manual [https://www.pca.state.mn.us/sites/default/files/parkinglotmanual.pdf here]. Other changes and updates to information on salt management will be posted in the [http://stormwater.pca.state.mn.us/index.php/What%27s_New What's new] page in the manual. Information on ''road salt and water quality'' can be found on [https://www.pca.state.mn.us/water/road-salt-and-water-quality MPCA's website]|alert-info}} | ||
+ | |||
This article provides information on preparing for winter operations | This article provides information on preparing for winter operations | ||
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**address the level of service, considering customer expectations, the hours and use of the building, priority access points and environmental concerns in the policy; and | **address the level of service, considering customer expectations, the hours and use of the building, priority access points and environmental concerns in the policy; and | ||
**spell out any additional strategies such as routes, chemicals, and application rate ranges. | **spell out any additional strategies such as routes, chemicals, and application rate ranges. | ||
− | : | + | :There are several winter maintenance policy plans available in the literature, including plans developed for the cities of [https://www.regina.ca/export/sites/Regina.ca/transportation-roads-parking/seasonal-maintenance/.galleries/pdfs/Winter-Maintenance-Policy.pdf Regina], [http://www.ci.superior.wi.us/DocumentCenter/View/1841 Superior, Wisconsin], and [https://www.sandwichmass.org/1497/Winter-Policies Sandwich, Massachusetts]. |
*Review the maintenance policy with the crew. | *Review the maintenance policy with the crew. | ||
*Inform customers of the maintenance policy. | *Inform customers of the maintenance policy. | ||
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===Getting prepared for winter=== | ===Getting prepared for winter=== | ||
*Calculate the area of the parking lots, service roads, and sidewalks. | *Calculate the area of the parking lots, service roads, and sidewalks. | ||
− | *Understand the | + | *Understand the environmental problems caused by snow, salt, and sand storage. Determine where and how to best store each item. |
*Understand the [http://stormwater.pca.state.mn.us/index.php/Preparing_for_winter_operations_for_winter_parking_lot_and_sidewalk_maintenance#Materials properties of various deicers], and then select the type(s) to use. | *Understand the [http://stormwater.pca.state.mn.us/index.php/Preparing_for_winter_operations_for_winter_parking_lot_and_sidewalk_maintenance#Materials properties of various deicers], and then select the type(s) to use. | ||
*Train the crew on proper [http://stormwater.pca.state.mn.us/index.php/Keeping_surfaces_clear_for_winter_parking_lot_and_sidewalk_maintenance#Application_Rates_for_Reduced_Environmental_Impacts application rates]. | *Train the crew on proper [http://stormwater.pca.state.mn.us/index.php/Keeping_surfaces_clear_for_winter_parking_lot_and_sidewalk_maintenance#Application_Rates_for_Reduced_Environmental_Impacts application rates]. | ||
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Calibration is an essential procedure to understand how much material will be discharged at a given setting. No matter how sophisticated or simple the operation, calibrate each piece of equipment in the fall of the year. Contact manufacturer for calibration instructions. | Calibration is an essential procedure to understand how much material will be discharged at a given setting. No matter how sophisticated or simple the operation, calibrate each piece of equipment in the fall of the year. Contact manufacturer for calibration instructions. | ||
− | ====Simple | + | ====Simple calibration for salt spreaders==== |
If the equipment has different settings, it must be calibrated for each setting and for each product, as they all flow differently. It generally takes a team of two or three people to calibrate equipment efficiently. | If the equipment has different settings, it must be calibrated for each setting and for each product, as they all flow differently. It generally takes a team of two or three people to calibrate equipment efficiently. | ||
− | ====Ground | + | ====Ground speed controlled spreaders==== |
Ground speed controlled spreaders are run by a computer in the cab and are tied to the speedometer and an auger or conveyor sensor in the rear of the truck. The application rate is set and the computer regulates the amount of salt discharged (regardless of the speed traveled) consistently. Most equipment used for winter maintenance of roads have ground speed controls. These are more effective and efficient systems than the manually controlled systems. | Ground speed controlled spreaders are run by a computer in the cab and are tied to the speedometer and an auger or conveyor sensor in the rear of the truck. The application rate is set and the computer regulates the amount of salt discharged (regardless of the speed traveled) consistently. Most equipment used for winter maintenance of roads have ground speed controls. These are more effective and efficient systems than the manually controlled systems. | ||
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===Storage of liquids=== | ===Storage of liquids=== | ||
− | *Know the freezing point of the liquid. This will determine if it can be stored outdoors. Salt brine (NaCl) will freeze at -6<sup>o</sup> F. | + | *Know the freezing point of the liquid. This will determine if it can be stored outdoors. Salt brine (sodium chloride - NaCl) will freeze at -6<sup>o</sup> F. |
*Tanks should be double-walled or have secondary containment. Secondary containment is like creating a bath tub around the tank so if the tank leaks, the “tub” captures the spill. | *Tanks should be double-walled or have secondary containment. Secondary containment is like creating a bath tub around the tank so if the tank leaks, the “tub” captures the spill. | ||
*Label the tank documenting its contents. | *Label the tank documenting its contents. | ||
*Click [https://www.pca.state.mn.us/waste/cleanup-contaminated-sites here] for more information on storage tanks. | *Click [https://www.pca.state.mn.us/waste/cleanup-contaminated-sites here] for more information on storage tanks. | ||
− | ===Storage of sand piles | + | ===Storage of sand piles=== |
*Winter sand is typically mixed with some deicer to prevent freeze-up of the pile; therefore, sand pile storage should be the same as salt pile storage. | *Winter sand is typically mixed with some deicer to prevent freeze-up of the pile; therefore, sand pile storage should be the same as salt pile storage. | ||
*Store leftover winter sand for next year. Do not use it for other purposes. | *Store leftover winter sand for next year. Do not use it for other purposes. | ||
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{{alert|[[File:Fish logo.png|50px|alt=dollar symbol]] '''Prevent groundwater contamination. Do not locate storage areas near wells. Limestone regions with fissures and sinkholes are very prone to groundwater contamination, as are those with sandy soils.'''|alert-info}} | {{alert|[[File:Fish logo.png|50px|alt=dollar symbol]] '''Prevent groundwater contamination. Do not locate storage areas near wells. Limestone regions with fissures and sinkholes are very prone to groundwater contamination, as are those with sandy soils.'''|alert-info}} | ||
− | ===Sidewalk | + | ===Sidewalk tips=== |
Always remove snow prior to applying deicers. Plow, blow, or sweep first; the chances of refreeze diminish and slush build-up is minimized. | Always remove snow prior to applying deicers. Plow, blow, or sweep first; the chances of refreeze diminish and slush build-up is minimized. | ||
*Sidewalks are the most over-salted areas in winter maintenance. | *Sidewalks are the most over-salted areas in winter maintenance. | ||
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{{alert|[[File:Dollar logo.jpg|25px|alt=dollar symbol]] '''Salt only needs to melt 1/16 inch to prevent the bond between the pavement and the ice. Save money by applying salt before the ice bonds to the surface it doesn’t need to melt through the ice.'''|alert-info}} | {{alert|[[File:Dollar logo.jpg|25px|alt=dollar symbol]] '''Salt only needs to melt 1/16 inch to prevent the bond between the pavement and the ice. Save money by applying salt before the ice bonds to the surface it doesn’t need to melt through the ice.'''|alert-info}} | ||
− | ===Building | + | ===Building entrances=== |
Steps are often the most over-salted area in all of winter maintenance. This overabundance of deicer causes damage to floors inside the building as salt and/or sand is tracked in. It causes problems outside of the building with deterioration of concrete and metal structures. Over applying deicer costs more money than necessary, pollutes the water, and does not provide any additional safety. The right amount of deicer and proper mechanical removal of snow and ice will yield better results. | Steps are often the most over-salted area in all of winter maintenance. This overabundance of deicer causes damage to floors inside the building as salt and/or sand is tracked in. It causes problems outside of the building with deterioration of concrete and metal structures. Over applying deicer costs more money than necessary, pollutes the water, and does not provide any additional safety. The right amount of deicer and proper mechanical removal of snow and ice will yield better results. | ||
− | A free short [https://www.pca.state.mn.us/water/road-salt-and-water-quality video for small site winter maintenance] is available. It is designed for those that do winter maintenance of small sites such as stairs, curb cuts, and handicap ramps. The video is a visual instruction tool useful for those who apply granular deicer to small areas outside building entrances. It recommends: | + | A free short [https://www.pca.state.mn.us/water/road-salt-and-water-quality video for small site winter maintenance] (scroll down on page) is available. It is designed for those that do winter maintenance of small sites such as stairs, curb cuts, and handicap ramps. The video is a visual instruction tool useful for those who apply granular deicer to small areas outside building entrances. It recommends: |
*Do site assessments, document drainage problems, and fix them in the summer (e.g., roof that drips on steps, downspout that drains to sidewalk). | *Do site assessments, document drainage problems, and fix them in the summer (e.g., roof that drips on steps, downspout that drains to sidewalk). | ||
*Always remove snow prior to applying deicers. The less snow, the less deicer required for a safer walking surface. | *Always remove snow prior to applying deicers. The less snow, the less deicer required for a safer walking surface. | ||
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{{alert|[[File:Dollar logo.jpg|25px|alt=dollar symbol]] '''Handheld spreaders and shakers, not scoops, should be used to apply deicer to steps and building entrances. This will save at least 50% of the salt normally used per winter without reducing the level of safety.'''|alert-info}} | {{alert|[[File:Dollar logo.jpg|25px|alt=dollar symbol]] '''Handheld spreaders and shakers, not scoops, should be used to apply deicer to steps and building entrances. This will save at least 50% of the salt normally used per winter without reducing the level of safety.'''|alert-info}} | ||
− | ===Parking | + | ===Parking lot tips=== |
*It is hard to walk and push shopping carts through salt and sand accumulations in parking lots. Sand is ineffective once it is on the pavement. Sweep it up to prevent a slippery situation. | *It is hard to walk and push shopping carts through salt and sand accumulations in parking lots. Sand is ineffective once it is on the pavement. Sweep it up to prevent a slippery situation. | ||
*Handicap parking spots are often over-salted and over-sanded. They should get the same amount of salt or sand as other areas. | *Handicap parking spots are often over-salted and over-sanded. They should get the same amount of salt or sand as other areas. | ||
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*Store snow downhill from any salt storage areas. Avoid water running through salt storage. | *Store snow downhill from any salt storage areas. Avoid water running through salt storage. | ||
− | + | ==Materials== | |
All products have pros and cons. No one material is suitable for every condition. It is best to have a variety to choose from to select the one that works the best, with the least amount applied, in a specific situation. Understand the melting properties of the deicers; do not use the product without understanding how it works. | All products have pros and cons. No one material is suitable for every condition. It is best to have a variety to choose from to select the one that works the best, with the least amount applied, in a specific situation. Understand the melting properties of the deicers; do not use the product without understanding how it works. | ||
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*Seek out products that allow for smaller application rates. | *Seek out products that allow for smaller application rates. | ||
− | ====Abrasives | + | ===Types of materials=== |
+ | This sections provides a discussion of the most commonly used materials for deicing. | ||
+ | |||
+ | ====Abrasives==== | ||
*Sand is an abrasive; it does not melt snow and ice. | *Sand is an abrasive; it does not melt snow and ice. | ||
*Abrasives provide traction on top of packed snow or ice. | *Abrasives provide traction on top of packed snow or ice. | ||
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====Salts==== | ====Salts==== | ||
− | *Sodium | + | *Sodium chloride (NaCl), magnesium chloride (MgCl<sub>2)</sub>, potassium chloride (KCl), and calcium chloride (CaCl<sub>2</sub>) are all considered salts. |
*Salt is a deicer; it will melt snow and ice. | *Salt is a deicer; it will melt snow and ice. | ||
*Salt lowers the freezing point of water from 32° F to a colder temperature. | *Salt lowers the freezing point of water from 32° F to a colder temperature. | ||
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*Salts have different melting characteristics, depending on the selection. | *Salts have different melting characteristics, depending on the selection. | ||
*Road salt (NaCl) is a granular product and is mined from the earth. | *Road salt (NaCl) is a granular product and is mined from the earth. | ||
− | *Magnesium | + | *Magnesium chloride (MgCl<sub>2</sub>) and calcium chloride (CaCl<sub>2</sub>) can naturally occur as liquids. |
*MgCl<sub>2</sub> and CaCl<sub>2</sub> are hygroscopic, drawing moisture from the air to the pavement. | *MgCl<sub>2</sub> and CaCl<sub>2</sub> are hygroscopic, drawing moisture from the air to the pavement. | ||
− | *Salt brine (NaCl) is commonly used at a 23.3 | + | *Salt brine (NaCl) is commonly used at a 23.3 percent concentration as this has the lowest freezing point and can be stored and handled down to -6°F. |
− | ====Acetates | + | ====Acetates==== |
*Acetates are chemically manufactured, not mined from the earth. | *Acetates are chemically manufactured, not mined from the earth. | ||
*Acetates are more expensive than chloride salts. | *Acetates are more expensive than chloride salts. | ||
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====Plant-based additives==== | ====Plant-based additives==== | ||
− | Corn, beet, molasses, or other organic additives are added to salt or salt brine to change its performance, though how they function as an ice melting agent is not well understood. Clear Roads (2015), a national resource consortium of state agencies, is studying this issue. | + | Corn, beet, molasses, or other organic additives are added to salt or salt brine to change its performance, though how they function as an ice melting agent is not well understood. [http://clearroads.org/ Clear Roads] (2015), a national resource consortium of state agencies, is studying this issue. |
*Often have very low ice melt capacity. | *Often have very low ice melt capacity. | ||
*May be used to reduce corrosion. | *May be used to reduce corrosion. | ||
*Are sticky and may help dry material stay on the surface longer. | *Are sticky and may help dry material stay on the surface longer. | ||
− | ===Testing=== | + | ===Testing the material=== |
− | When ordering a liquid product in bulk, test it. If it is NaCl brine it should be 23.3 | + | When ordering a liquid product in bulk, test it. If it is NaCl brine it should be 23.3 percent. If it is another liquid, use the vendor recommended density and test to confirm. Hydrometers are the tools for testing the density of liquids. They are inexpensive and look similar to a thermometer. |
Research the product, understand the practical melting temperature, and know the list of ingredients. Take time to test the materials to ensure that they perform as expected. Product labeling can be confusing; some list the eutectic temperature while others list the lowest practical melting temperature. | Research the product, understand the practical melting temperature, and know the list of ingredients. Take time to test the materials to ensure that they perform as expected. Product labeling can be confusing; some list the eutectic temperature while others list the lowest practical melting temperature. | ||
The list of ingredients may or may not be included. Often, the percentage of each ingredient is not included. Do not rely solely on the bag or on the manufacturer’s literature. There are no labeling requirements; manufacturers can choose to label products in their own way. | The list of ingredients may or may not be included. Often, the percentage of each ingredient is not included. Do not rely solely on the bag or on the manufacturer’s literature. There are no labeling requirements; manufacturers can choose to label products in their own way. | ||
− | ===Cost and | + | ===Cost and availability of materials=== |
− | Of the deicers, NaCl is typically the cheapest and easiest to find. Because of this, it is widely used and overused. Sodium chloride is only effective at pavement temperatures above | + | Of the deicers, NaCl is typically the cheapest and easiest to find. Because of this, it is widely used and overused. Sodium chloride is only effective at pavement temperatures above 15<sup>o</sup>F. Because it doesn’t work well at colder temperatures, it is often over-applied in attempts to increase its effectiveness. At temperatures lower than 15<sup>o</sup>F degrees, switch to a different deicer. |
Non-chloride deicers are more difficult to find and often cost more. Take the time to source and try non-chloride products if there are concerns from the professionals or customers about the long-term effects of chlorides on the lakes and rivers. All deicers have environmental impacts but the impacts of chlorides are very long-term. | Non-chloride deicers are more difficult to find and often cost more. Take the time to source and try non-chloride products if there are concerns from the professionals or customers about the long-term effects of chlorides on the lakes and rivers. All deicers have environmental impacts but the impacts of chlorides are very long-term. | ||
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{{alert|[[File:Dollar logo.jpg|25px|alt=dollar symbol]] '''Using 50/50 salt/sand mix is generally half right or half wrong. Using a salt/sand mix leads to over application of both materials.'''|alert-info}} | {{alert|[[File:Dollar logo.jpg|25px|alt=dollar symbol]] '''Using 50/50 salt/sand mix is generally half right or half wrong. Using a salt/sand mix leads to over application of both materials.'''|alert-info}} | ||
+ | ==Conditions affecting winter maintenance== | ||
+ | The following conditions affect winter management strategies and options. | ||
===Weather === | ===Weather === | ||
− | |||
Know existing and potential weather conditions for a successful snow and ice control operation. Monitor the weather closely to prepare to act early in storm situations. Check the [http://www.noaa.gov National Weather Service], local TV stations, or website weather. A Road Weather Information System (RWIS) is available for [http://www.rwis.dot.state.mn.us/ free on-line] at. The RWIS provides real time pavement temperatures and other information from locations around the state. | Know existing and potential weather conditions for a successful snow and ice control operation. Monitor the weather closely to prepare to act early in storm situations. Check the [http://www.noaa.gov National Weather Service], local TV stations, or website weather. A Road Weather Information System (RWIS) is available for [http://www.rwis.dot.state.mn.us/ free on-line] at. The RWIS provides real time pavement temperatures and other information from locations around the state. | ||
− | ===Pavement | + | ===Pavement temperature=== |
+ | [[File:Hand held temperature sensor.PNG|right|thumb|300 px|alt=This photo of Hand held temperature sensor|<font size=3>Hand held temperature sensor</font size>]] | ||
Pavement and air temperature are different. Know the pavement temperature to determine the proper amount and type of material to apply. Weather stations report air temperature which is measured at least 6 ft. in the air. The air temperature is not helpful when trying to determine what to apply to surfaces on the ground. | Pavement and air temperature are different. Know the pavement temperature to determine the proper amount and type of material to apply. Weather stations report air temperature which is measured at least 6 ft. in the air. The air temperature is not helpful when trying to determine what to apply to surfaces on the ground. | ||
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{{alert|[[File:Dollar logo.jpg|25px|alt=dollar symbol]] '''Knowing the pavement temperature allows the application of the proper amount of material for each situation. '''|alert-info}} | {{alert|[[File:Dollar logo.jpg|25px|alt=dollar symbol]] '''Knowing the pavement temperature allows the application of the proper amount of material for each situation. '''|alert-info}} | ||
− | + | ===Speed of melting=== | |
− | |||
− | |||
− | |||
− | ===Speed of | ||
Will the road salt used have time to work or is it better to switch to a different deicer? This chart will aid in making that decision. | Will the road salt used have time to work or is it better to switch to a different deicer? This chart will aid in making that decision. | ||
{{:Speed of melting}} | {{:Speed of melting}} | ||
− | |||
{{alert|[[File:Dollar logo.jpg|25px|alt=dollar symbol]] '''Do not use dry road salt below 15º F. This wastes money and time.'''|alert-info}} | {{alert|[[File:Dollar logo.jpg|25px|alt=dollar symbol]] '''Do not use dry road salt below 15º F. This wastes money and time.'''|alert-info}} | ||
− | ===Practical | + | ===Practical melting temperature=== |
Use care when reading the melting temperature on bags of deicers. The package often lists the eutectic temperature, which is the lowest possible melting temperature. At this temperature, it would take a very long time to melt ice. Instead, use the lowest practical melting temperatures in the chart below or ask the supplier for the practical melting temperature and the time it takes to melt ice at that temperature. It should be noted that there is not a standard measure for determining the lowest practical melting temperature. Across the literature there are a range of values. In the References and Resources section there are lists of several websites to learn more about the lowest practical melting temperature. | Use care when reading the melting temperature on bags of deicers. The package often lists the eutectic temperature, which is the lowest possible melting temperature. At this temperature, it would take a very long time to melt ice. Instead, use the lowest practical melting temperatures in the chart below or ask the supplier for the practical melting temperature and the time it takes to melt ice at that temperature. It should be noted that there is not a standard measure for determining the lowest practical melting temperature. Across the literature there are a range of values. In the References and Resources section there are lists of several websites to learn more about the lowest practical melting temperature. | ||
{{:Lowest practical melting temperature}} | {{:Lowest practical melting temperature}} | ||
+ | |||
+ | <noinclude> | ||
+ | ==Related pages== | ||
+ | *[[Background information for winter parking lot and sidewalk maintenance]] | ||
+ | *[[Preparing for winter operations for winter parking lot and sidewalk maintenance]] | ||
+ | *[[Keeping surfaces clear for winter parking lot and sidewalk maintenance]] | ||
+ | *[[Evaluating the effectiveness for winter parking lot and sidewalk maintenance]] | ||
+ | *[[Environmental tips for winter parking lot and sidewalk maintenance]] | ||
+ | *[[Cost savings tips for winter parking lot and sidewalk maintenance]] | ||
+ | *[[Results and evaluation for winter parking lot and sidewalk maintenance]] | ||
+ | *[[Material conversions for winter parking lot and sidewalk maintenance]] | ||
+ | *[[References for winter parking lot and sidewalk maintenance]] | ||
+ | *[[Additional resources and links to websites for winter parking lot and sidewalk maintenance]] | ||
+ | </noinclude> | ||
+ | |||
+ | [[Category:Level 2 - Pollutants/Chloride]] | ||
+ | [[Category:Level 2 - Management/Winter management]] |
This article provides information on preparing for winter operations
Start now—develop a maintenance policy or plan that guides winter operations. A little planning and communication up-front can help achieve better results throughout the season.
Reduce risk by having a solid written winter maintenance policy and training program that utilizes best management practices. Schedule training for supervisors, staff, and customers.
The MPCA has three Smart Salting training classes available:
Check the MPCA website to find out about upcoming training opportunities.
This section describes initial actions in preparing for winter maintenance.
Inspect storm drains in the fall. Remove obstructions such as leaves, sticks, and trash to prepare for the spring melt. Because storm drains lead to lakes, rivers, ponds, and wetlands, never use salt to open frozen storm drains. Salt used to thaw frozen drains harms aquatic life. Use non-chemical methods such as heat to open drains.
Poor drainage on the maintenance surfaces will result in icy surfaces and will increase the risk of safety problems. These areas cause the application of salt on non-snow event days in the winter. To remedy this, inventory the site and note drainage problems. Make a checklist so the professional or client can fix these drainage problems in the summer.
Examples of drainage problems:
The trend in winter maintenance is to use less material to accomplish the same results. Following this trend will reduce environmental impacts and save money. Below are listed a few tips, but there are many other innovations in the equipment area that can help to reduce application rates.
Calibration is an essential procedure to understand how much material will be discharged at a given setting. No matter how sophisticated or simple the operation, calibrate each piece of equipment in the fall of the year. Contact manufacturer for calibration instructions.
If the equipment has different settings, it must be calibrated for each setting and for each product, as they all flow differently. It generally takes a team of two or three people to calibrate equipment efficiently.
Ground speed controlled spreaders are run by a computer in the cab and are tied to the speedometer and an auger or conveyor sensor in the rear of the truck. The application rate is set and the computer regulates the amount of salt discharged (regardless of the speed traveled) consistently. Most equipment used for winter maintenance of roads have ground speed controls. These are more effective and efficient systems than the manually controlled systems.
The equipment vendor will have specific calibration instructions for the operation based the type and brand of equipment. Contact them; it is in their best interest to provide instructions to calibrate and correct product use. This is the basic principle behind calibrating a ground speed controlled spreader:
Manual controlled spreaders fall into two categories. Those that have an auger or conveyor and those that are gravity fed. They operate by selecting a setting that changes the size of the discharge opening and/or the auger or conveyor speed. More or less salt may be discharged depending on the speed of application. Most parking lot and sidewalk spreaders fit into one of these two categories.
The basic principle behind calibrating an auger/conveyor spreader is to choose a setting, run the spreader for a timed interval, and weigh the discharge. Record the discharge and repeat for all settings. In the end, there will be data that tells the operator how much material will be delivered at each setting. With this information, the operator can choose the proper setting. Without this information, they have no guidance on which setting to use. Calibration is different for gravity fed spreaders..
The following calibration example applies to manual control spreaders.
See the References and Resources section for a full size form to copy for calibration. This is how the empty form looks.(Keep a stack of these on a clipboard when ready to begin the calibration.)
Calibration Chart for auger or conveyor systems
Link to this table
Date: | |||||
Spreader #: | |||||
Material: | |||||
Setting | Pounds per minute | 5 mph (X12) | 10 mph (X6) | 15 mph (X4) | 20 mph (X3) |
---|---|---|---|---|---|
1 | |||||
2 | |||||
3 | |||||
Fill in the header information and column 2, the discharge weight per setting.
Step 2 Calibration Chart for auger or conveyor systems
Link to this table
Date: August 8, 2015 | |||||
Spreader #: A4219 | |||||
Material: Rock salt | |||||
Setting | Pounds per minute | 5 mph (X12) | 10 mph (X6) | 15 mph (X4) | 20 mph (X3) |
---|---|---|---|---|---|
1 | 10 | ||||
2 | 22 | ||||
3 | 34 | ||||
Back in the shop, do the calculations to fill in the rest of the blanks. Multiply the weight in column 2 with the multiplier in the top row. This provides the pounds per mile that needed to fill in the table.
Step 3 Calibration chart for auger or conveyor systems
Link to this table
Date: August 8, 2015 | |||||
Spreader #: A4219 | |||||
Material: Rock salt | |||||
Setting | Pounds per minute | 5 mph (X12) | 10 mph (X6) | 15 mph (X4) | 20 mph (X3) |
---|---|---|---|---|---|
1 | 10 | 1201 | 60 | 40 | 30 |
2 | |||||
2 | 22 | 264 | 132 | 88 | 66 |
3 | 34 | 408 | 204 | 136 | 102 |
1 top half of each row = lbs/lane mile. To get this number, multiply lbs/min by the factor shown for each speed
2 bottom half of each row = lbs/1000 sq ft. To find this, divide the number in the top half by 63
Divide by 63 to convert pounds per lane mile to pounds per 1,000 square feet. This is very useful for parking lot and sidewalk applications.
Step 4 Calibration Chart for auger or conveyor systems
Link to this table
Date: August 8, 2015 | |||||
Spreader #: A4219 | |||||
Material: Rock salt | |||||
Setting | Pounds per minute | 5 mph (X12) | 10 mph (X6) | 15 mph (X4) | 20 mph (X3) |
---|---|---|---|---|---|
1 | 10 | 1201 | 60 | 40 | 30 |
1.92 | 1.0 | 0.6 | 0.5 | ||
2 | 22 | 264 | 132 | 88 | 66 |
4.2 | 2.1 | 1.4 | 1.0 | ||
3 | 34 | 408 | 204 | 136 | 102 |
6.5 | 3.2 | 2.2 | 1.6 |
1 Top half of each row = lbs/lane mile. To get this number, multiply lbs/min by the factor shown for each speed
2bottom half of each row = lbs/1000 sq ft. To find this, divide the number in the top half by 63
This is applicable for equipment that does not have a motorized delivery system such as an auger. This type of equipment might be a pickup mounted spreader, gator mounted spreader or a hand push spreader. Gravity flow equipment is typically controlled by gate opening and speed of application.
The following step-by-step process describes an example calibration for a gravity flow spreader.
Repeat step #1 for various settings
Example calibration chart for gravity flow equipment
Link to this table
Equipment: | ||||||
Material: | ||||||
Date: | ||||||
A | B | C | D | E | F | G |
---|---|---|---|---|---|---|
Speed | Lever position or gate setting | Pounds spread in 10 feet1 | Spread width in feet | Coverage area in sq. ft. (D x 10)* | Application rate in lbs./1000 ft2 (1000/E x C) | Application rate in lbs./lane mile (12’ width) (F x 63.4) |
Example | ||||||
20 MPH | Half-closed | 0.4 lbs | 13 feet | 130 sq. ft. | 3.1 lbs. per 1000 sq. ft. | 196 lbs./mile |
1If changing the test strip length, adjust the title in column C and the multiplier in column E.
The following shortcuts can be used in calibrating the spreader.
Even without calibrating the equipment, the amount of material to use can be determined but will take more time to calculate. Know the material, the size of the area to be treated, and the pavement temperature, then consult the application rate chart (application rate section) and do the math. Without calibration, the way to evenly distribute the recommended amount across the maintenance area must be determined by the professional. This approach may work well for treating sidewalks using the “chicken feed” method. For example:
Use the following links to access the calibration charts discussed above
The amount of deicer needed is based on the size of the parking lot or sidewalk. Here are simple ways to calculate the area of the parking lot or sidewalk.
The area, or square feet, of a square or rectangle is equal to the length (L) times the width (W).
The area, or square feet, of a circle is equal to πr2, where π (pi) equals 3.1416 and r is half of the distance across the circle.
The area, or square feet, of a right triangle is equal to the length (L) times the width (W) divided by 2
This section provides best practices and tips for winter parking lot and sidewalk maintenance.
Always remove snow prior to applying deicers. Plow, blow, or sweep first; the chances of refreeze diminish and slush build-up is minimized.
Steps are often the most over-salted area in all of winter maintenance. This overabundance of deicer causes damage to floors inside the building as salt and/or sand is tracked in. It causes problems outside of the building with deterioration of concrete and metal structures. Over applying deicer costs more money than necessary, pollutes the water, and does not provide any additional safety. The right amount of deicer and proper mechanical removal of snow and ice will yield better results.
A free short video for small site winter maintenance (scroll down on page) is available. It is designed for those that do winter maintenance of small sites such as stairs, curb cuts, and handicap ramps. The video is a visual instruction tool useful for those who apply granular deicer to small areas outside building entrances. It recommends:
To determine the amount of deicer needed for steps, stairs, and small sites:
All products have pros and cons. No one material is suitable for every condition. It is best to have a variety to choose from to select the one that works the best, with the least amount applied, in a specific situation. Understand the melting properties of the deicers; do not use the product without understanding how it works.
The best way to reduce impacts, save money and maintain customer satisfaction is to:
This sections provides a discussion of the most commonly used materials for deicing.
Corn, beet, molasses, or other organic additives are added to salt or salt brine to change its performance, though how they function as an ice melting agent is not well understood. Clear Roads (2015), a national resource consortium of state agencies, is studying this issue.
When ordering a liquid product in bulk, test it. If it is NaCl brine it should be 23.3 percent. If it is another liquid, use the vendor recommended density and test to confirm. Hydrometers are the tools for testing the density of liquids. They are inexpensive and look similar to a thermometer. Research the product, understand the practical melting temperature, and know the list of ingredients. Take time to test the materials to ensure that they perform as expected. Product labeling can be confusing; some list the eutectic temperature while others list the lowest practical melting temperature.
The list of ingredients may or may not be included. Often, the percentage of each ingredient is not included. Do not rely solely on the bag or on the manufacturer’s literature. There are no labeling requirements; manufacturers can choose to label products in their own way.
Of the deicers, NaCl is typically the cheapest and easiest to find. Because of this, it is widely used and overused. Sodium chloride is only effective at pavement temperatures above 15oF. Because it doesn’t work well at colder temperatures, it is often over-applied in attempts to increase its effectiveness. At temperatures lower than 15oF degrees, switch to a different deicer.
Non-chloride deicers are more difficult to find and often cost more. Take the time to source and try non-chloride products if there are concerns from the professionals or customers about the long-term effects of chlorides on the lakes and rivers. All deicers have environmental impacts but the impacts of chlorides are very long-term.
Salt and sand mixes are commonly used to stretch the salt budget. This is an ineffective practice. Salt and sand work against each other. To save money, use deicers when melting is needed and sand for temporary traction to buy time at temperatures too low for deicers to be effective. Pre-wetted sand has shown to be effective in keeping sand in place longer on icy surfaces.
The following conditions affect winter management strategies and options.
Know existing and potential weather conditions for a successful snow and ice control operation. Monitor the weather closely to prepare to act early in storm situations. Check the National Weather Service, local TV stations, or website weather. A Road Weather Information System (RWIS) is available for free on-line at. The RWIS provides real time pavement temperatures and other information from locations around the state.
Pavement and air temperature are different. Know the pavement temperature to determine the proper amount and type of material to apply. Weather stations report air temperature which is measured at least 6 ft. in the air. The air temperature is not helpful when trying to determine what to apply to surfaces on the ground.
Air temperature measurements are generally the same in a given area, but pavement temperatures in the same general location can vary greatly. Pavement temperatures are influenced by exposure to sun, pavement type, and subsurface materials.
The same air temperature in November and January will often accompany very different pavement temperatures.
The hand-held temperature sensors can be purchased from auto part stores for less than $100. Some temperature sensors only accurately monitor in the warm temperature range, confirm the one purchased measures in the cold temperature range. Mirror-mounted temperature sensors are also available; they are less likely to be lost or stolen, but do cost more and are generally not available at an auto parts store. RoadWatch by Commercial Vehicle Group, Inc. is one example of this type of sensor. A small investment in equipment will improve performance.
Will the road salt used have time to work or is it better to switch to a different deicer? This chart will aid in making that decision.
Speed of melting
Link to this table
Pavement Temp. ºF | One Pound of dry Salt (NaCl) melts | Melt Times |
---|---|---|
30 | 46.3 lbs. of ice | 5 min |
25 | 14.4 lbs. of ice | 10 min. |
20 | 8.6 lbs. of ice | 20 min |
15 | 6.3 lbs. of ice | 1 hour |
10 | 4.9 lbs. of ice | Dry salt is ineffective and will blow away before it melts anything |
5 | 4.1 lbs. of ice | |
0 | 3.7 lbs. of ice | |
-6 | 3.2 lbs. of ice |
Use care when reading the melting temperature on bags of deicers. The package often lists the eutectic temperature, which is the lowest possible melting temperature. At this temperature, it would take a very long time to melt ice. Instead, use the lowest practical melting temperatures in the chart below or ask the supplier for the practical melting temperature and the time it takes to melt ice at that temperature. It should be noted that there is not a standard measure for determining the lowest practical melting temperature. Across the literature there are a range of values. In the References and Resources section there are lists of several websites to learn more about the lowest practical melting temperature.
Lowest practical melting temperature
Link to this table
Chemical | Lowest Practical Melting Temp. | Eutectic Temp. | Optimal Concentration |
---|---|---|---|
NaCl (Sodium Chloride) —Delivered as rock salt, can be made into a brine. The basis of many bagged blends. Corrosive. Inexpensive. Very available. Most commonly us used without a corrosion inhibitor added, but corrosion inhibited products are available | 15º F | -6º F | 23% |
MgCl2 (Magnesium Chloride)—Delivered primarily as a liquid, other forms available. Used for anti-icing, pre-wetting and stockpile treatments. Corrosive. Higher cost. Often has a corrosion inhibitor added. Often added to salt brine. | -10º F | -28º F | 27 to 30% |
CaCl2 (Calcium Chloride)—Delivered as flakes, pellets, or liquid. Corrosive. Most effective ice melter at very cold temperatures. Sometimes used incorrectly to open storm drains. Higher cost. Often has a corrosion inhibitor added. Often added to salt brine. | -20º F | -60º F | 30% |
CMA (Calcium Magnesium Acetate)—Delivered as a powder, crystals, pellets, or liquid. Liquid CMA is used mainly on automated bridge deicing systems. Non-corrosive to steel, biodegradable. Alternative for areas where chloride use must be limited. Higher cost. | 20º F | -18º | 32% |
KAc (Potassium Acetate)—Delivered as a liquid. Often used on automated bridge deicing systems and airports. Use for anti-icing, deicing. Non-corrosive to steel but corrosive to galvanized, biodegradable. Alternative for areas where chloride use must be limited. Higher cost. | -15º F | -76º F | 50% |
Blends— Both chlorides and acetates exist in blends. Talk to the supplier and determine the lowest practical melting temperature, the optimal concentration and the basic components in the blend. Most blends are centered on rock salt since it is cheap. | |||
Winter Sand/Abrasives—Winter sand has salt mixed in it to keep it from freezing. Abrasives should be used for cold temperatures when deicers are not effective. Want to minimize salt % in sand. | Never melts—provides traction only |
This page was last edited on 2 February 2023, at 20:40.