Standards for contaminated sites

Standards are legally enforceable limits of substances or parameters as specified in legislation, regulations, permits and approvals.

An environmental standard is a "safe" concentration of a substance in soil, water, sediment, or vapour. Standards are different from guidelines and objectives because they are legally enforceable.

There are two categories of standards in the Contaminated Sites Regulation (CSR):

• Numerical
• Risk-based

These standards are designed to protect human and environmental health from the harmful effects of substances released to the environment by human activities.

On this page

• Numerical standards
• Risk-based standards
• Substances without remediation standards
• Using the standards

Numerical standards

Numerical standards set generic maximum allowable concentrations of substances in soil, groundwater, vapour, and sediment that can be broadly applied across the province without consideration for site-specific conditions. 

Types of numerical standards

Numerical standards come in various forms, including:

• CSR Schedules 3.1 to 3.4 Standards
  These are generic numerical standards described in the CSR and apply broadly to various sites. 
• Site-Specific Numerical Standards
  These are derived under Protocol 2 using models, equations, site data, and specific site information. Site-specific standards only apply to the particular site they were derived for.
• Director’s Interim Numerical Standards
  These are temporary standards that can be adopted by the director to protect human or ecological health. The standards are valid for one year unless incorporated into the regulation.

While not classified as a numerical standard, local background concentrations can help determine if a site is contaminated when elevated concentrations of substances occur naturally in a region.

Information for qualified professionals

Qualified professionals are responsible for selecting the appropriate numerical standards for a site. For guidance on this process, visit Selecting numerical standards

Risk-based standards

Risk-based standards set acceptable risk levels to protect human and environmental health from exposure to substances at sites. Sites that meet risk-based standards may not need physical remediation.

To apply risk-based standards, a risk assessment must be completed for a site. This process assesses risks to human and environmental receptors posed by contamination at a site. It often requires additional data collection and complex technical and scientific analysis.

Information for qualified professionals

Qualified professionals are responsible for creating risk assessments. For guidance on this process, visit Guidance for risk assessment

Substances without remediation standards 

Some substances don't have numerical standards in the CSR. These are known as non-prescribed substances. 

If a non-prescribed substance is identified at a site and a director thinks it might pose an unacceptable risk to human or environmental health, they may:

• Refuse to issue a certification document
• Establish a Director's Interim Standard for the non-prescribed substance, or
• Impose requirements that they consider necessary to mitigate or eliminate the risk posed by the non-prescribed substance

Guidance for non-prescribed substances

Using the standards

Results of a site investigation are compared with the applicable numerical standards to determine:

• Whether a site is contaminated
• Whether contamination has spread, and where it has spread to
• When a site has been sufficiently cleaned up
• When soil relocation can occur

A site is contaminated if a substance concentration exceeds any of the applicable numerical standards. 

Unlike numerical standards, risk-based standards cannot determine if a site is contaminated or assess the extent of contamination. They are used to determine if remediation is complete. A site is considered remediated if all substance concentrations in the media are less than or equal to the applicable standards after remediation.