As the winter season approaches, many Canadian cities and towns will once again rely on the use of road salt for public safety during Canada's harsh winters. Although this practice is essential, it has led to a significant environmental challenge: the increasing salinization of our landscapes. Soils, groundwater and surface waters across Ontario are experiencing rising levels of chloride, which can be toxic to aquatic life, degrade soil structure, damage salt-intolerant vegetation and corrode critical infrastructure.
For years, soil excavated from these saline areas was considered waste – an expensive burden that had to be hauled away and disposed of. Today, however, a decisive shift in perspective, underpinned by regulatory innovation and sound scientific evidence, is transforming this challenge into a unique opportunity. By implementing best practices, we can transform saline soils from a liability into a valuable resource that drives a circular economy.
A new regulatory framework
The cornerstone of this transformation is Ontario's On-Site and Excess Soil Management Regulation (O. Reg. 406/19), which fundamentally redefines excess soil as a resource that can be meaningfully reused. This framework has been significantly improved by an important change in 2022, O. Reg. 555/22, which dealt specifically with saline soils. This change provides greater flexibility and clarity and officially designates saline soil as a reusable resource rather than waste under certain conditions. It allows project managers to divert large quantities of this material from landfills by allowing its storage on industrial or commercial properties and, with certain restrictions, on residential, park and institutional properties.
Crucially, regulations require that these activities do not harm the environment. Special rules prevent placement near sensitive areas such as drinking water wells and bodies of water, thereby protecting our vital water resources.
The importance of professional planning
Successful saline soil reuse requires a structured and collaborative approach anchored in a saline landscape plan. This plan, developed by a qualified professional such as a Professional Agriculturalist (P.Ag.), a member of the Ontario Association of Landscape Architects (OALA), a Professional Geoscientist (P.Geo.) or a Professional Engineer (P.Eng.), serves as a roadmap for a project.
It begins with a thorough site assessment, including soil testing for parameters such as electrical conductivity (EC) and sodium adsorption ratio (SAR), to characterize the level of salt contamination and ensure regulatory compliance. This detailed understanding enables strategic management on site.
For example, the plan may include adding saline soil to a depth of 1.5 meters or more below topsoil to create a root zone that can accommodate a greater diversity of plants. This collaborative planning process ensures that all stakeholders are aligned and facilitates the safe and effective reuse of land in a way that achieves sustainable results.
Choosing the right vegetation
A crucial part of any successful salt landscape is selecting the appropriate vegetation. Planting species that cannot tolerate increased salinity will result in failure and result in poor growth and plant mortality. Fortunately, nature provides a robust range of salt-tolerant plants that can thrive in these difficult conditions. In addition to being aesthetically pleasing, these species also play an important functional role in stabilizing soil and preventing erosion.
Options for Ontario landscapes include hardy native trees such as red oak (Quercus rubra) and white spruce (Picea glauca) and hardy shrubs like staghorn sumac (Rhus typhina). A diverse mix of perennials and grasses, including switchgrass (Turned into panic) and Canada anemone (Anemone canadensis), can form a vibrant and healthy ground cover. By choosing the right plants, we create resilient ecosystems that require less maintenance and less effort.
Integration with green infrastructure
The opportunities for reusing saline soil extend directly to the creation of modern green infrastructure. Projects such as bioswales and rain gardens designed to manage stormwater runoff can effectively utilize saline soils as part of their engineered growing media. These systems help mitigate the impacts of urbanization by capturing, filtering and infiltrating runoff before it enters our storm drains and waterways. By designing with a salt-tolerant plant community, these green infrastructure facilities also function effectively on roadsides and parking lots where salt spray is common.
This innovative use not only provides sustainable drainage for excess soil, but also creates multifunctional green spaces that reduce urban heat island effects, provide habitat for wildlife, and enhance the beauty of our communities.
Closing the loop for the future
The journey of saline soils – from a problematic waste stream to a fundamental element of sustainable development – is an impressive example of the circular economy in action. By leveraging a progressive regulatory framework and implementing science-based best practices, we can close the loop on soil management. This approach offers a number of benefits: it dramatically reduces disposal costs for developers and municipalities, saves limited landfill space, and reduces the need for the extraction of virgin aggregates and topsoil. More importantly, it allows us to build greener and more resilient communities.
The intelligent and planned reuse of saline soils is no longer a niche concept; It is an essential practice for any organization committed to environmental protection and sustainable urban growth.
Jose Haig, M.NRES, P.Ag, Cert. Urban Ecologies is lead advisor to Reclaim Environmental.
To read the original version of this article in Environment Journal Quarterly, click here.
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