Sustainable Salt Management Resource Hub

Posted October 14, 2021

DID YOU KNOW?

Every winter, Canada applies approximately 7 million tonnes of road salt!

Are you using too much road salt?

Best practices indicate that approximately 50g/m2 of salt is an appropriate amount, while TRCA data has shown that up to 10x the appropriate amount of salt is commonly applied on parking lots and walkways, costing businesses an average of $34,175 per year in additional costs.

  • White picture with black dots/salt (left): How much salt should be applied – 50mg/m2
  • Heavy salt application photo (right): How much salt is typically applied

Using too much salt not only costs more money but studies have shown it to be less effective at reducing accidents than best practice levels because friction with the ground is inhabited. 

Overview: Why Does Sustainable Salt Management Matter?

Salt is a critical component of any good winter maintenance plan to reduce accidents, injury, and mortality associated with icy and snow conditions. But applying too much salt shortens the life of pavements and hastens the corrosion of building materials and vehicles. Salt applied to parking lots and roads also pollutes groundwater, damage roadside vegetation, alters the hydrologic properties of soils, and finds its way into streams and rivers, where it harms fish and other aquatic life. Unless salt reduction has been on your radar, chances are you are using too much salt in your winter maintenance practices.

Businesses can help reduce over-salting by ensuring that salt is applied responsibly on parking lots and walkways. An easy way to do this is by ensuring that your snow and ice maintenance contract includes provisions requesting that industry best practices be employed, and operators are adequately trained. These will not only help ensure the ‘right’ amount of salt is applied to manage risk but can also save money and prevent damage to building infrastructure.

Through this hub, PPG members will have access to a range of resources suited to commercial, industrial and institutional property owners on how they can incorporate sustainable salt management into their winter maintenance operations and procurement practices. As well, learn from other PPG members taking action to reduce road salt, saving them time and money, and protecting the environment and human safety.

SAVE ON SALT, TIME AND MONEY
Protect the Environment, Infrastructure, and Human Safety

What Can You Do as a Business?

1. Understand the environmental, financial and safety impacts
2. Review salt management certifications for property managers and contractors
3. Review property for winter maintenance best practices
4. Update procurement policy for winter maintenance contractor
5. Pilot and evaluate success
6. Share learnings with the PPG membership!

“We have just gone through an RFP process and selected a contractor who is onboard with helping Seneca reduce our road salt use by 50% this winter and additional amounts the following years.” – Don Forster, Seneca College

Want to learn more about stormwater quality and pollution prevention? Upgrade your PPG membership by joining a consortium. Contact: ozit.bittner@trca.ca to discuss your options.

The Environmental Impacts of Road Salt

Provided is a collection of resources demonstrating evidence that chloride concentrations (salt) are highest in heavily urbanized watersheds, such as Humber, Mimico, and Etobicoke. High chloride concentrations are harmful to the environment by creating toxic environments for aquatic species, mobilizes other contaminants in the environment such as heavy metals, and threatens drinking water supplies. Evidence suggests that runoff from urbanized areas with large expanses of impermeable surfaces contribute to high concentrations of chloride in adjacent waterways. Remember, the salt you use on your property gets washed away into storm drains, and into local waterways and eventually, Lake Ontario.

Watch this video as a friendly reminder that “wherever water flows, salt goes”.

Source: https://www.facetsjournal.com/doi/full/10.1139/facets-2020-0068

The map above indicates a range of chloride concentrations in the Humber, Etobicoke, Mimico and Don River watersheds during July and August. The map can be understood as follows:

  • Green diamonds: chloride concentrations less than the federal chronic threshold of 120mg/L
  • Yellow circles: chloride concentrations over the chronic threshold and below the acute threshold of 640 mg/L
  • Red cross: chloride concentrations over the acute threshold and below 1000 mg/L
  • Black star: chloride concentrations over 1000 mg/L
  • Green background layer indicates rural zone, red indicates urbanizing zone, and grey indicates urban zone

Mimico Creek has the highest chloride concentrations with more than 75% of the sites exceeding the acute threshold

Etobicoke Creek had all values exceeding the chronic threshold and several above the acute level

The Humber River showed the lowest chloride concentrations in general, with about one-quarter of the sampling locations having values below the chronic threshold.

Road Salt Pollution is Not Just a Winter Issue!

Which watersheds does YOUR business impact? Locate yourself on this map and consider the downstream impacts of your road salt use.

Seneca College: 5 campuses across the GTA– aimed at a 50% reduction in road salt usage! (marked with blue stars)

Dextran Products: with a smaller property footprint, located in Scarborough, Dextran Products only uses salt when and where necessary.

 

Podcast

Snow Magazine Podcast: Exploring Salt’s Impact
University of Toronto researchers Don Jackson and Lauren Lawson discuss their recent research on winter rock salt use in urban environments and what commercial contractors must know about the long-term impact current deicing practices may have on urban environments and infrastructure.

Research

2020 Annual Surface Water Quality Summary

2020 Annual Surface Water Quality Summary – Chloride is discussed in section 3.2.1
Prepared by Lyndsay Cartwright, Ecosystem and Climate Science
May, 2021

Summary 

This report presents results for selected parameters from the 2020 surface water quality sampling. It provides a general overview and description of the range of water quality conditions across the TRCA jurisdiction during 2020. Results include data collected as part of the Provincial Water Quality Monitoring Network (PWQMN) and RWMP. The PWQMN is administered by the MECP in partnership with conservation authorities across Ontario and PWQMN stations within the TRCA jurisdiction are considered part of the RWMP. This report and associated data can assist in identifying areas of concern, elevated levels of contaminants, and can be used to affirm both poor and good water quality in different land use areas. The 2020 results should be interpreted with caution since water quality samples were collected independent of precipitation, and one year of data is insufficient to represent normal conditions at stations and watersheds. For example, 12 monthly samples from one site may be biased towards baseflow or stormwater runoff conditions. The 2011-2015 Surface Water Quality Summary report should be used as the most recent characterization of stream water quality across the region (TRCA 2017). Furthermore, the COVID-19 pandemic began in March 2020 which resulted in changes in both sample collection and laboratory analysis. 

The two studies below on chloride concentrations in TRCA watersheds were conducted in partnership with TRCA’s Watershed Planning Team

Salty Summertime Streams: Road Salt Contaminated Watersheds

Salty summertime streams—road salt contaminated watersheds and estimates of the proportion of impacted species
Lauren Lawson & Donald A. Jackson
Published March 11, 2021

Abstract 
Road salt runoff is a leading cause of secondary freshwater salinization in north temperate climates. Increased chloride concentrations in freshwater can be toxic and lead to changes in organismal behavior, lethality, biotic homogenization, and altered food webs. High chloride concentrations have been reported for winter months in urban centers, as road density is highest in cities. However, summer chloride conditions are not typically studied as road salt is not actively applied outside of winter months, yet summer is when many taxa reproduce and are most sensitive to chloride. In our study, we test the spatial variability of summer chloride conditions across four watersheds in Toronto, Canada. We find 89% of 214 sampled sites exceeded the federal chronic exposure guidelines for chloride, and 13% exceeded the federal acute guidelines. Through a model linking concentration to cumulative proportion of impacted species, we estimate 34% of sites show in excess of one-quarter of all species may be impacted by their site-specific chloride concentrations, with up to two-thirds of species impacted at some sites. Our results suggest that even presumed low seasons for chloride show concentrations sufficient to cause significant negative impacts to aquatic communities.

Trends and Legacy of Freshwater Salinization

Trends and legacy of freshwater salinization: untangling over 50 years of stream chloride monitoring
Bhaswati Mazumder3,1, Christopher Wellen1, Georgina Kaltenecker2, Ryan J Sorichetti2 and Claire J Oswald3,1
Published 12 August 2021

Abstract 
Excessive use of road salts to maintain safe winter travel conditions leads to increasing chloride (Cl) concentrations in streams, damaging the structure and function of freshwater ecosystems. Long-term increasing stream Cl trends are generally attributed to increases in urban land cover, however recent research shows that even relatively rural streams can retain Cl and exceed water quality guidelines in summer after road salting has stopped. Untangling the relative influences of long-term changes in streamflow and urban growth on Cl trends is critical for making informed decisions about road salt management. The portion of Cl trends not explained by changes in streamflow or urban growth could be due to changes in road salt application rates and/or legacy Cl in groundwater that is slowly making its way to streams. This study assessed seasonal, long-term stream Cl trends across the Province of Ontario, Canada, where urbanization accelerated and road salt management plans started to develop since early 2000s. We compared stream Cl trends over salting and non-salting seasons with urban growth estimates from two independent time periods, 1965–1995 and 2002–2018. For a subset of sites with sufficient flow data in the periods analyzed, we parsed the seasonal trends into flow and management trend components. We found that most of the variance in the management trend component in the winter salting season could be explained by urbanization, while about half of it could be explained in the summer non-salting season. We further analyzed Cl estimates in low-flow conditions to explore the extent of subsurface contributions to Cl trends, and concluded with a summary of challenges and recommendations for future studies on road salt legacy in streams.

 


MEMBERS-ONLY CONTENT INCLUDES:

      • Procurement best practices for winter maintenance including webinars, presentations, certifications and training resources, and guides
      • Case studies from PPG members taking action to reduce road salt use on their properties
      • Additional resources for those wanting to learn more about the environmental impacts of road salt and what private land-owners can do to make a positive difference

Enter the password below to access exclusive content for PPG members!

• Don’t have a password? Please contact admin@partnersinprojectgreen.com.

• Not yet a member? Sign up now!