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Background concentrations

Last updated on March 2, 2023

Concentrations that occur naturally in a geographic area are considered local background concentrations.

Under the Environmental Management Act (EMA), the Contaminated Sites Regulation (CSR) has provisions to address local background concentrations of substances in environmental media, such as:

  • Soil
  • Groundwater
  • Sediment
  • Surface water
  • Vapour

If substances at a site are above the numerical soil or water quality standards and are thought to be local background concentrations, an application to establish a local background concentration can be made to the ministry.

When a local background concentration is established, it effectively replaces the CSR environmental quality standards for the determination of a contaminated site (CSR Section 11(3) or the remediation standard (CSR Section 18).

The applicant must establish a local background concentration prior to applying for:

  • Approval in Principle
  • Certificate of Compliance
  • Determination of Contaminated Site
  • Scenario 3 release notice under the site identification process

Applications to establish a local background concentration must be accompanied by a Contaminated Sites Service Application (CSSA) (Online) as described on the Apply for services page.

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Background concentrations in soil

Please visit the Background concentrations in soil page for more information. 

 

Background concentrations in groundwater

During site investigation, naturally occurring concentrations of substances may be identified in groundwater in excess of the CSR numerical standards.

If this is suspected, Protocol 9: Establishing Local Background Concentrations in Groundwater (PDF, 400KB) provides options for establishing local background concentrations at a site.

 

Background concentrations databases 

The ministry has developed soil and groundwater databases that may be used at sites where local background concentrations are above the CSR numerical soil or water standards.

Further information on the data and databases themselves can be found on the Background concentrations databases page.

 

Background concentrations in other media

During site investigation, naturally occurring concentrations of substances may be identified in sediment, vapour, or surface water in excess of the CSR numerical standards.

If this is suspected, an application under Protocol 6: Applications with Approved Professional Recommendations and Pre-approvals (PDF, 406KB) can be prepared for ministry review.

 

The information on this web page does not replace the legislative requirements in the EMA or its regulations and it does not list all provisions for contaminated site services.

If there are differences between this information and the Act, Regulation, or Protocols, the Act, Regulation, and Protocols apply.