Toronto Salt Management Plan
Balances Safety/Environment

By Gary Welsh, P. Eng.
Director, Transportation Services
City of Toronto

The City of Toronto has created a Salt Management Plan, a pro-active program to balance the City’s objectives to preserve wintertime safety and mobility on 5,100 kilometers (3,160 miles) of roadways while minimizing adverse environmental impacts.   It’s a delicate balancing act, an enormous management challenge.  Toronto roads receive about 130 cm (65 inches) of snow every winter and the City uses 200 trucks and more than 140,000 metric tonnes (154,000 short tons) of salt to keep its roads safe and passable.  It is a big job.   Toronto’s salt management plan makes it possible to get that job done and done right.

A recent Environment Canada assessment of the environmental impacts of four chloride salts used in winter maintenance focused political attention on the need for salt management improvements. 

Even before the final assessment report was published in December 2001, the City audited its existing operations in the spring of 2001 and identified a variety of activities should be carried out to make the city’s storage and use of salt more effective.  Among the concerns, the

·         high rate of salt applications in certain situations

·         need for improved storage and handling of salt resources

·         lack of computerized controls on some spreader vehicles

·         need for improved training for operators and supervisors and

·         lack of proper calibration on many vehicles.

The City took immediate steps to deal with some of these concerns.   Training provides the fastest significant benefit.  Supervisors and equipment operators were taught when to salt and how much salt is required in certain circumstances.  They were also trained on the use of new equipment, the use of alternative deicing materials and the importance of keeping accurate records.  More than 400 staff participated in the training, part of an on-going program that initially relied on outside training professionals.  The City is in the process of upgrading its in-house training capability.

In addition, the City developed new salt storage guidelines.  Plans were put in place to ensure that salt is kept dry when delivered to city storage locations and stored in properly maintained structures.

Finally, new record-keeping systems were created and implemented to ensure that managers have accurate records of salt usage by route and by vehicle.

These quick-fix steps were just the beginning. Since then, the City has required electronic controls be installed on all contracted salt-spreading equipment and most of the city’s in-house fleet.  Automated controls will allow operators to control both the rate of salt flow as well as the spinner speed, ensuring, in varying storm conditions, that only as much salt as needed is used and that more of the salt remains on the road, not on the shoulder.

The City had moved to a straight-salt strategy, but the new plan will include using a mix of sand and salt when conditions warrant.  When local roads and sidewalks are covered with packed snow and ice, a mixture of sand and salt is often an effective method of winter maintenance.  However, this strategy must be used judiciously.  Sand is an abrasive and does not provide for ice removal.   Also, it increases the amount of grit and dust that must be swept every spring and adds to the amount of sediment entering the storm sewer system.

More importantly is another new strategy:  pre-wetting the road salt with a liquid such as salt brine prior to spreading on the roadway.  The pre-wetting has two benefits.  First, pre-wetting minimizes the over-spray of the salt beyond the road surface since the salt granules do not bounce once they strike the road surface.  This means that less salt is used for the same level of service.  Second, the pre-wetting activates the salt faster making the application more effective.  Some of the city’s salt trucks have already been retrofitted with anti-icing and pre-wetting technology.  Within three years, most of the city’s fleet will have this equipment. The city is continuing to explore this technology to better determine the benefits and to reduce the costs of retrofitting spreading equipment with the pre-wetting feature.

In the winter of 2002, the City of Toronto undertook several new measures to better manage the city’s deicing programs. 

Traditionally, the city has used a combination of Environment Canada road weather services and the services of a private forecaster (World Weather Watch) for timely and accurate weather information to assist in decision-making.  Both services rely on broad-based weather forecasting that is fine-tuned by modeling and additional local information gathering.  Now, the city has a new tool to assist in gathering information: RWIS, Road Weather Information Systems.  RWIS consists of local automated weather reporting stations installed along the roadway.  These stations use sensors embedded in the roadway and basic above-ground weather instruments to provide continuous information on air, surface and sub-surface conditions.  The four units currently in place enable the city to best decide when, where and how much salt is required depending on conditions. Also, the city has installed mobile infrared pavement temperature sensors on many of the patrol and supervisory vehicles to assist staff in determining actual road temperature conditions.

RWIS can reduce the amount of salt needed to keep roads safe.  On any number of occasions during the past winter, wet roads were not deiced as they were in past years because staff recognized that road temperatures were above freezing and there was sufficient salt residue (as determined by the RWIS sensors) to provide for safe driving conditions. 

The issue of snow removal and disposal is another piece of the puzzle.   The city recently completed a study to determine the best location of snow disposal sites.  At present, the city is addressing the feasibility of relocating up to five locations that are near rivers.  A series of public meetings were held to keep the public up-to-date on any proposed changes the city considered making to these operations.

Among the changes being considered:

·         Engineering disposal sites to ensure that run-off is properly treated

·         Increased use of portable snow melters and the city augmenting its existing fleet of five mobile snow melters 

·         Revising site operating guidelines to ensure that each site is maintained properly during the winter, restored properly during the spring season and prepared properly during the fall

Another important, pro-active aspect of the plan is the on-going environmental monitoring program.  City staff continues to monitor chloride concentration along rivers, keeping detailed records on how much salt has been dispersed on each route.

While the City has been able to make certain changes, it is critical that the public be informed about winter issues and the city’s actions in reducing salt use yet maintaining safe roads and sidewalks.  The City uses a number of communications strategies to inform the public about the importance of using salt to maintain safe roads, about initiatives in place to enable the city to reduce salt use and to encourage property owners and other agencies to make better use of salt.  These include a transportation newsletter, active media relations and a citizens’ website, http://www.city.toronto.on.ca/transportation/snow

Since the end of last winter, the City’s Transportation Services Division has undertaken additional projects including

·         Performing an audit of the 2001-2002 winter season

·         Improving salt storage facilities

·         Finalizing the snow disposal strategy

·         Preparing new winter maintenance contracts and

·         Reviewing staff training needs. 

Overall, the City of Toronto’s Salt Management Plan has achieved some significant successes. City staff has increased its knowledge with respect to new technology and environmental issues, facilities for handling salt have been reviewed and upgraded, equipment has been improved and new technology has been used to better forecast weather and road conditions.  The result has been that less salt is being used because salt is being applied and distributed more effectively.  The City’s winter maintenance program costs have decreased significantly.

Environment Canada has praised Toronto’s salt management plan as a positive step in improving how the municipality handles salt resources.  Toronto’s comprehensive checklist of action items made a lot of sense for the City.  Perhaps Toronto’s path of progress will be useful to other cities.

In addition to the changes that have been completed, the City continues to review new technologies and practices on an annual basis and will implement pilot projects aimed at improving the usage of salt resources.