What is a Contaminated Site?
Updated: Sep 16, 2021
A contaminated site is defined as an area of land in which the soil or underlying groundwater or sediment contains a hazardous waste or substance in an amount or concentration that exceeds numerical levels specified in provincial and federal policies and regulations.
A site is contaminated if it is unsuitable for specific uses of land, water and sediment.
A site can also be contaminated naturally due to the geology of the area (asbestos or radiation)
Many sites in First Nations in Canada became contaminated during past industrial or commercial uses as well as a result of aging or damaged heating fuel tanks. Such activities often resulted in chemicals and other toxic materials being spilled or deposited on land.
The most common substances found at sites in Canada are heavy metals such as lead, arsenic, cadmium, and mercury. Organic chemicals, including benzene and toluene in gasoline, occur at about two-thirds of the sites. Chlorophenols are common at wood treatment operations, as are benzo[a]pyrene and naphthalene from creosote.
Polychlorinated biphenyls (PCBs) often occur at sites where electrical equipment was used.
Related: Understanding waste management: Creating a First Nations plan that works!
In Canada, there are over 23,000 known and suspected Federal contaminated sites, and in Ontario specifically there are over 1,000 sites on First Nations. Petroleum hydrocarbons are especially common on reserve land as many communities rely on diesel generated power and heat. Many First Nations communities are not connected to the electrical grid.
The reliance on diesel fuel for electricity and heat has contributed greatly to the amount of sites contaminated by petroleum hydrocarbons on reserve land. Communities in the North are shown to have more contaminated sites.
This is partly due to the fact that a lot of these communities do not have all season road access making transportation of remediation materials and workers difficult, in comparison to communities with all season road access.
Why are Contaminated Sites a concern?
Contaminants pose a threat to human health, the environment, and safety. Their potential effects on humans range from minor physical symptoms to life-threatening diseases such as cancer. Children are often most at risk from exposure to contaminated soil, air, water, and food.
Even if a site does not pose a threat to people, it can still be an environmental hazard. Soil, water, and sediment at a site may contain substances that can negatively impact fish or mammals; impair the reproduction of birds; and accumulate in the food web.
These effects can be severe enough to impair, or cause imbalance in, ecological functions or systems.
How are Contaminated Sites Identified?
There are several different ways in which potentially contaminated sites can be identified. The majority of these avenues are dependent upon previous investigations and/or reports that may have been generated for the site.
Ways in which a site may be identified without accessing the actual property include:
previous environmental record(s);
internal environmental programs;
complaints by citizens;
similarities to other known contaminated sites;
visual or olfactory (smell) evidence of previous leaks, spills or discharges; and
the nature of current or past activities at the site or adjacent properties.
Who is Responsible for Remediating a Contaminated Site?
In Canada, the “polluter pays” principle applies to legal liability in regards to contaminated sites. Therefore, the private company or owners of the property are typically liable for the costs of cleaning up (remediating) the land in which they contaminate. The nature and extent of any liability is not always clear.