This document combines several documents related to winter parking lot and sidewalk maintenance. Individual documents can be viewed by clicking on the appropriate link below. Fact sheets are not included in this combined document.
The purpose of this manual is to deliver practical advice to those managing parking lots and sidewalks. This manual will help to make proactive, cost-effective, environmentally conscious choices in winter parking lot and sidewalk management. This knowledge will provide the opportunity to become a leader in the industry by operating more efficiently and reducing environmental impacts.
A single approach will not work for the range of conditions Minnesota experiences; different strategies are needed for different regions and different weather conditions. We encourage continuing to test, document, and refine the practices from this manual.
Customer service is the key to success. Best Management Practices (BMP) keep parking lots and sidewalks safe and also reduce environmental impacts. Educating customers on the proper methods of snow removal and ice control (and of the value of this approach) can create a good and long-standing relationship.
Customers want reliable service. Providing a well-planned and well-executed winter maintenance program will have a positive impact. Using the latest technologies will increase the ability to provide reliable service.
Customers want to hire educated winter maintenance professionals. This manual will provide the necessary information to increase staff knowledge on the best practices for winter maintenance.
Customers and the public want safe parking lots and sidewalks. Understanding the materials, weather and application rates, provide a head start on controlling icy, slippery parking lots, and sidewalks.
Clean and neat parking lots and sidewalks are important to the public. By using less material and increased winter sweeping, pedestrians will track less material into buildings and there will be less damage to flooring. Proper snow storage makes debris removal in the spring easier. Covered storage of deicers will reduce loss of material, protect water, and is more aesthetic. Using BMPs and lower application rates will keep parking lots and sidewalks looking neat.
Customers also want affordable snow and ice control. The use of sophisticated chemicals and equipment may require a larger budget up-front; however, these costs can be balanced by reduced on-going costs. Reducing the need for sweeping, floor and rug maintenance, parking lot striping, and snow and ice maintenance time will allow for cost savings.
Minnesotan’s value water resources and the protection of lakes, streams, and wetlands is important. Educating customers how sustainable winter maintenance protects water resources is necessary.
Only 2.5 percent of all of the water on this planet is freshwater (not saltwater). Of that, less than 1 percent is available for use, with the majority of the freshwater frozen in ice (Freshwater Crisis n.d.). There is a limited supply of water on this planet and that water is reused, recycled and dispersed, often over long periods of time (Healthy Rivers, 2004).
Because the supply of water can be limiting, it is important to keep it clean. Once polluted, water may become unusable or require cleanup. Elevated concentrations of chloride can diminish the quality of water. Chloride concentrations are increasing in many surface waters and in shallow groundwater across Minnesota.
Deicers can be very damaging to both soil and vegetation. Efforts to keep salt off vegetation are needed. Examples include driving slower when applying deicers, turning down spinner speeds to reduce spread pattern, using drop spreaders on sidewalks, storing snow piles on hard surfaces, and reducing application rates. One source of information about salt-tolerant plants is the Plant Selector from Minnesota Department of Transportation.
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 section provides information on keeping surfaces clear during winter.
Anti-icing is the prevention of ice accumulation and build-up on surfaces. Deicing is the removal of ice that has accumulated on surfaces.
Anti-icing is a proactive approach. It should be first in a series of strategies for each winter storm. Applying a small and strategic amount of liquid on the pavement before a storm will prevent snow and ice from bonding to the pavement. This buys time for the clean-up efforts.
Anti-icing is like frying eggs: grease the pan and the eggs come out easily with no mess to clean up. Like greasing the frying pan, the purpose of anti-icing is to keep snow from sticking to the pavement. Anti-icing provides safer pavement during the event and faster clean up after the event.
Anti-icing requires about ¼ the material and 1/10 the overall cost of deicing. It can increase safety at the lowest cost, and is effective and cost-efficient when correctly used and approached with realistic expectations.
Anti-icing prevents formation of frost. It can be effective for up to several days depending on the weather conditions.
The basic equipment needed includes: pavement temperature sensor, storage tank, spray truck system, transfer pump, hoses, and fittings.
What to do
Test the application rates and spray pattern to become confident in preventing the bonding of ice without creating a slimy or slippery situation.
Tip: Stream nozzles prevent slippery conditions better than fan spray.
Tip: Too little CaCl2 or MgCl2 is safer than too much.
What not to do
Deicing is a reactive operation where a deicer is applied to the top of an accumulation of snow, ice, or frost that has already bonded to the pavement surface and can no longer be physically removed. Deicing costs more than anti-icing in materials, time, equipment, and environmental damage. Deicing is the “traditional” approach to winter maintenance.
Removing ice that has already bonded to the pavement is difficult. Removing it mechanically can damage equipment and surfaces. Generally, enough ice must be melted chemically to break the bond between the ice and the pavement. This requires larger amounts of chemical, making deicing much less efficient than anti-icing.
Use the application rate table to help with deicing. Using recommended rates will help with these common problems:
Tip: The goal is not to melt everything. The goal is to penetrate through the ice and snow and break the bond so the pavement can be plowed.
Pre-wetting and pretreating both mean getting dry material wet. Salt only melts snow and ice when it is in solution (dissolved). Dry salt does nothing until it is dissolved. Liquids applied to dry salt jump-start the melting process and penetrate ice and snow pack faster. Wet materials stick to the pavement and are less likely to end up in the nearby vegetation.
When integrating the liquids, decrease the application rate of the granular product. This is a common mistake made by new users of liquids.
Pretreating is mixing a liquid deicer into the stockpile of salt or sand. It can be purchased as a product already mixed and ready to use or can be created. To create a pre-treated stockpile, add liquids conservatively. The dry material can only hold so much liquid before leaching occurs. Watch the storage area to make sure it can contain the wet salt pile. Test mixing skills and observe the amount of leaching on a small stockpile before doing this on a large scale.
Pre-wetting is combining liquid from a tank to dry material from the hopper at the point of discharge. The most common set up is on a truck but it can be configured for smaller equipment. The liquid and granular usually come together at the spinner or auger.
While pre-wetting requires some equipment changes, it provides flexibility to switch the amount and type of liquid.
Tips:
Use winter sand and other abrasives when temperatures are too cold for deicing chemicals to be effective. But be aware that sand does not melt anything. It provides temporary traction and only when it is on top of snow and ice. When sand is in contact with the pavement, sweep it up. It is no longer useful and can only harm the environment. Sand on dry pavement can cause skidding.
Sweep the sand from the parking lot areas midwinter as well as in the spring. Trailer-type power sweepers are available that can be hauled behind a pickup truck. Smaller power brooms or sweepers may be used on sidewalks. Workers should wear a dust mask to avoid inhalation of the fine dust particles.
Effective application rates are based on many factors, including type and rate of precipitation, air and pavement temperature, forecast and temperature trend, humidity, dew point, type of surface and subsurface material, and sun exposure. The application rate tables used in this book have been taken from the Minnesota Snow and Ice Control Field Handbook for Snowplow Operators, Second Revision (LRRB 2012). They were converted from gallons or pounds per lane mile to gallons or pounds per 1000 square feet.
These application rates are not perfect but are to be used as goal to work toward. Develop specific application rate tables to standardize performance. Track application rates measure and improve performance. Modify the practices incrementally over time to fit the needs. Make it a goal to reduce application rates and keep surfaces safe.
One application rate will not fit all situations; how long an application lasts depends on:
Anti-icing application rates. These are a starting point only. Adjust based on experience.
Link to this table
Condition | Gallons/1000 sq. ft. | Other Products | |
---|---|---|---|
CaCl2 or MgCl2 | Salt Brine(NaCl) | ||
1. Regularly scheduled applications | 0.2 - 0.4 | 0.3 – 0.6 | Follow manufacturers’ recommendations |
2. Prior to frost or black ice event | 0.2 - 0.4 | 0.3 – 0.6 | |
3. Prior to light or moderate snow | 0.2 - 0.4 | 0.3– 0.8 | |
CAUTION: Too high an application rate may result in slippery conditions or tracking. |
How to use the anti-icing rate table above:
Example: The parking lot is 20,000 square feet. The chart tells how much to apply for 1,000 square feet. The plan is to apply brine prior to light or moderate snow. Do a calculation to see how much brine is needed:
Tip: To convert from gallons to ounces: multiply the result by 128.
These rates are based on road application guidelines (LRRB 2012).
Develop specific application rates by adjusting the current rates incrementally downward toward the guidelines. Where temperature categories overlap, select the rate most applicable to the present situation.
Application rates for deicing
Link to this table
Pavement Temp. (ºF) and Trend (↑↓) | Weather Condition | Maintenance Actions | Application Rate in lbs./per 1000 square foot area | |||
---|---|---|---|---|---|---|
Salt Pre-wetted/Pretreated With Salt Brine | Salt Pre-wetted/ Pretreated With Other Blends | Dry Salt | Winter Sand (abrasives) | |||
>30º↑ | Snow | Plow, treat intersections only | 0.75 | 0.5 | 0.75 | not recommended |
>30º↑ | Frz. Rain | Apply chemical | 1.25 | 1.0 | 1.5 | not recommended |
30º↓ | Snow | Plow & apply chemical | 1.25 | 1.0 | 1.5 | not recommended |
30º↓ | Frz. Rain | Apply chemical | 1.5 | 1.25 | 1.75. | not recommended |
25 - 30º ↑ | Snow | Plow & apply chemical | 1.25 | 1.0 | 1.5 | not recommended |
25 - 30º ↑ | Frz. Rain | Apply chemical | 1.5 | 1.25 | 1.75 | not recommended |
25 - 30º ↓ | Snow | Plow & apply chemical | 1.25 | 1.0 | 1.5 | not recommended |
25 - 30º ↓ | Frz. Rain | Apply chemical | 1.75 | 1.5 | 2.25 | 3.25 |
20 - 25º ↑ | Snow or Frz. Rain | Plow & apply chemical | 1.75 | 1.5 | 2.25 | 3.25 for frz. rain |
20 - 25º ↓ | Snow | Plow & apply chemical | 2.0 | 2.0 | 2.75 | not recommended |
20 - 25º ↓ | Frz. Rain | Apply chemical | 2.5 | 2.0 | 3.0 | 3.25 |
15º to 20º↑ | Snow | Plow & apply chemical | 2.0 | 2.0 | 2.75 | not recommended |
15º to 20º↑ | Frz. Rain | Apply chemical | 2.5 | 2.0 | 3.0 | 3.25 |
15º to 20º↓ | Snow or frz. rain | Plow & apply chemical | 2.5 | 2.0 | 3.0 | 3.25 for frz. rain |
0 to 15º ↑ ↓ | Snow | Plow, treat with blends, sand hazardous areas | not recommended | 3.0 | not recommended | 5.0 spot treat as needed |
< 0º | Snow | Plow, treat with blends, sand hazardous areas | not recommended | 4.5 | not recommended | 5.0 spot treat as needed |
All application rates are based on thoroughly cleared surfaces
Using the example above:
The following information is useful for evaluating the effectiveness of winter parking lot and sidewalk maintenance.
When snow and ice control operations have ended after the storm, evaluate what was done, what worked, and what could be changed to improve operations.
Tip: Save extra salt at the end of the season. Do not apply just to get rid of it.
Good documentation leads to reduced use of materials, more effective snow and ice control, reduced environmental impacts, and cost savings.
Anti-icing data form
Link to this table
Location: | ||||
---|---|---|---|---|
Date: | ||||
Air temperature | Pavement temperature | Relative humidity | Dewpoint | Sky - cloud cover |
Reason for applying: | ||||
Location: | ||||
Chemical: | ||||
Application Time: | ||||
Application Amount | ||||
Observation (after event): | ||||
Observation (efore next event): | ||||
Name: |
Documentation form for deicing
Link to this table
Operator: | |||
---|---|---|---|
Location: | |||
Event Began: | Date | Time | |
Event ended: | Date | Time | |
Event type:
|
|||
Total precipitation: | |||
Pavement temperature: | |||
Air temperature: | |||
Dew point:: | |||
Temperature Trend: | |||
Material used: | |||
Amount used: | |||
Application rate: | |||
Observations: |
The Winter Parking Lot and Sidewalk Maintenance Manual contains environmental tips identified with the following alert box.
Below is a summary of environmental tips found in the winter parking lot and sidewalk maintenance manual.
The Winter Parking Lot and Sidewalk Maintenance manual identifies cost savings tips with the following alert box.
Below is a list of cost savings tips found in the winter parking lot and sidewalk maintenance manual.
The first winter maintenance training and certification workshops were held in 2005. After holding several classes, it was determined that a training manual was needed.
The Winter Parking Lot and Sidewalk Maintenance Manual was written in 2006 and the training classes using the manual started in the winter of 2006-2007. In order to evaluate the effectiveness of the training, three class exercises were created. These exercises show potential rate reductions, potential change in practices, and evaluate the training program. The results from the in class exercises were compiled at the end of the 2007-2008 winter season and are shown below.
In 2007-2008, 345 people attended 14 Winter Parking Lot and Sidewalk Maintenance Workshops and filled out the forms used to evaluate the course. The summary of all the exercises is given below.
Attendees were given a survey about the use of BMPs. Out of the recommended BMPs:
Comments from those attending class:
Following the winter season, follow up interviews were conducted to learn more about the winter maintenance changes made since training. The individuals interviewed had attended the training and volunteered to be part of our follow up research on the effectiveness of the training class. Several examples of these interviews are included below.
Michael Soderlund attended the Parking Lot Training in October, 2007. After the training, many new successful changes were implemented. Overall, the District of Superior reduced their total use of deicers. One of the biggest steps forward was the production of their own brine. Michael said that everything is currently working well and there is no marked reduction in quality. Many District of Superior workers were initially hesitant about the new practices, but after a few tries they realized that the new methods work just as well or even better. The material application rates were greatly reduced, especially in the middle school and high school. The actual reduction rates are given below.
Rates:
Reduction in ice melt use: 33.3% Reduction in cost: 33.1%
Over the past few years, the UMN recognized the need to become much more environmentally conscious with winter maintenance and storm water management. They made many changes in their snow removal program; two key areas were employee training and calibration of equipment. By increasing awareness of proper application rates, they were able to significantly decrease the amount of deicing chemical used. They started an aggressive anti-icing program with liquid magnesium chloride for their sidewalks and salt brine for the streets and loading docks. Pre-storm applications were extremely successful in reducing the bond of snow and ice to walks as well as giving them more response time on the front end of snow events. They focused on mechanical removal of snow as their first line of defense and they have changed the main deicer for walks from a blended material to straight magnesium chloride. They dramatically reduced the sand in their sidewalk and street program which has saved them time and money in spring clean-up and long term savings are expected in storm sewer maintenance. Small amounts of sand are still used as pattern indicators for their sidewalk trucks and for use during extreme cold weather. The numbers speak for themselves:
Material # 1 – Rock Salt
Material #2 – Ice Melt (Magnesium Chloride - MgCl2)
Material #3 – Sand
NSC is a national facility management company that services commercial properties in 22 states. NSC’s responsibility is to manage all building services which include hiring and managing winter maintenance contractors. While working in his prior role as Regional Manager for Minnesota and North Dakota, Bob Rush required all of his Minnesota winter maintenance contractors to be trained and certified on the best practices. As Director of Operations he has implemented a regional training program based on the Minnesota program. This allowed NSC to expand the best practices training to all winter maintenance contractors in cold weather states. Bob has taken many steps to reduce the impacts of winter maintenance and to improve the safety of his operations
Bob required all suppliers in the seven county metro area to switch to a standardized treated salt for parking areas. He helped calibrate all truck mounted spreading equipment to ensure they were not over-applying the deicer. Bob required all Twin City Metro and Duluth area suppliers to switch to a mag/hex for sidewalks. This standardized the deicer which helped the suppliers determine the correct application rates per sq. ft. based on temperature and location of the sidewalk.
He requested that all Twin City Metro suppliers attend the MPCA snow training program. He rewarded the suppliers that were able to show their certifications. NSC held regional training sessions with all contractors, reviewed best practice for snow removal, and discussed the proper techniques and timing for deicer application. Bob requires preseason re-training of large suppliers to refresh them on the best practices. He expanded the material that was developed by the MPCA and trained his 14 Regional Managers on best practices, impact on the environment, and the need for continual training. They, in turn, introduced the training material into the larger markets such Salt Lake City, Denver, Omaha, and Boise.
They eliminated sand use in Minneapolis and Denver and continue to educate the maintenance contractors on the impact that sand has on the environment. In the first year of the program, NCS reduced deicer use by 15-20% in parking lots and by 20-25% on sidewalks. They hope to see additional reductions in the amount of wasted material by continuing to help the teams understand the use of technology and best practices. Bob developed a working group to continue to research better practices and material with the goal of reducing deicer use and our impact on the environment.
Joe’s Lawn and Snow is a small company located in the Twin Cities area. Joe attended the certification class in the winter of 2013-2014 and sent four employees. The changes were implemented for the last half of the season. They normally would have expected to use 20 tons of salt and only used 9 tons.
Prior to attending the class, they relied on application rates listed on the deicers and their best judgment to determine how much material to apply and did not calibrate their equipment. They learned a lot in the class and implemented many practices in their first year. Practices implemented included:
They were not able to reliably calibrate and adjust their old spreader so they purchased a new one. He plans to add mud flaps with pockets to prevent salt from going all over the truck and catch extra salt which they will reuse. They tested areas in parking lots to determine the best application rates. Before winter, they mark the edges of their parking lots with blue poles and used a different color to indicate where snow should be stacked. They have a covered salt storage area on one of their properties. It is a 20 x 30’ concrete walls and “tarp-type” top. It has a subfloor and a capture drain. It was a $20,000 investment. They had this prior to training. They do spring and fall sweeping.
They reduced their application rates by about ½ and then adjusted them up based on results as needed. With the changes made, they were able to reduce their salt usage by about 50% without reducing their results.
After attending the Parking Lot Training in 2005, Charles Cadwell’s company examined their procedures for applying salt and deicing chemicals at Ridgedale Center and found areas that were candidates for improvement. Practices in previous years included using salt rather carelessly and applying it to attempt to keep snow from accumulating during a storm. As such, it was quite common to apply 12 to 14 tons of salt during a given storm. Since training, they examined their practices and have taken measures to reduce usage of salt products.
They reduced the speed setting on our auger to slow the feed rate of salt to the wheel. At the same time, they maintained the speed of the wheel and that made for better dispersion of the salt (more even dispersion of salt and greater coverage in a given load).
They inspected the truck tailgate because in previous years, they had a problem with spillage that resulted in "piles" of salt being dropped at random during turns or when hitting potholes or speed bumps. They found gaps between the tailgate sander and the truck bed that they filled with weather stripping. That forced all salt to be fed through the auger and baffle so that spillage was eliminated. That further increased the coverage per given load that was achieved.
Based on the information provided in training, they no longer apply salt or other chemicals during a storm. Salt is applied after the snow has been mechanically removed. The one exception to this is where some material might be needed to provide traction and permit traffic safety at stop signs or on slopes. In these situations, the materials are applied only sparingly after plowing is done.
Average salt usage for a given snow event is now five to six tons. That is based on the number of loader buckets put in the truck where one bucket is considered to be one ton (Ridgedale does not have a scale). That form of measurement is standard for what they did in previous years and from one contractor to another.
They were able to further reduce salt applications the winter of 2007 -2008 by educating the customer on the mechanical removal being the major step and only when that is complete is it reasonable to apply salt to the pavement. The mall was very receptive to only using salt when absolutely necessary. Supporting this approach, they were also able to maintain good performance in terms of the number of slip-and-fall incidents that occurred due to ice or snow. That supported the approach of using mechanical removal and then salt application as a standard process.
Salt - sand yard to ton conversions
Link to this table
Yards | Sand (tons) | Salt (tons) |
---|---|---|
1 | 1.4 | 1.1 |
2 | 2.8 | 2.2 |
3 | 4.2 | 3.2 |
4 | 5.6 | 4.3 |
5 | 7.0 | 6.4 |
6 | 8.4 | 6.5 |
7 | 9.8 | 7.6 |
8 | 11.2 | 8.6 |
9 | 12.6 | 9.7 |
10 | 14.0 | 10.8 |
11 | 15.4 | 11.9 |
12 | 16.8 | 13.0 |
13 | 18.2 | 14.0 |
14 | 19.6 | 15.1 |
15 | 21.0 | 16.2 |
16 | 22.4 | 17.3 |
17 | 23.8 | 18.4 |
18 | 25.2 | 19.4 |
19 | 26.6 | 20.5 |
20 | 28.0 | 21.6 |
The following formulas and the above quick reference table will help to convert between tons and cubic yards. Weights will vary depending upon moisture content.
Use these tables to convert application rates between pounds per lane mile and pounds per 1000 square feet.
Conversion of pounds per lane mile to pounds per 1000 square feet
Link to this table
lbs./ lane mile | lbs./1000 square feet |
---|---|
25 | 0.4 |
50 | 0.8 |
75 | 1.2 |
100 | 1.6 |
125 | 2.0 |
150 | 2.4 |
175 | 2.8 |
200 | 3.2 |
225 | 3.5 |
250 | 3.9 |
275 | 4.3 |
300 | 4.7 |
350 | 5.5 |
Conversion of pounds per 1000 square feet to pounds per lane mile
Link to this table
lbs./1000 square feet | lbs./ lane mile |
---|---|
0.5 | 32 |
0.75 | 48 |
1 | 63 |
1.25 | 79 |
1.5 | 95 |
1.75 | 111 |
2 | 127 |
2.25 | 143 |
2.5 | 159 |
2.75 | 174 |
3 | 190 |
3.25 | 206 |
5 | 317 |