Contaminated sites

What is the Contaminated Sites program?

The Contaminated Sites program of Environment and Natural Resources (ENR) is responsible for carrying out the assessment and remediation of abandoned contaminated sites that fall under the responsibility of the Government of the Northwest Territories (GNWT).

What are the different types of contaminated sites in the NWT?

During negotiations to finalize the NWT Land and Resources Devolution Agreement, the GNWT and Canada decided which government would be responsible for various contaminated sites in the Northwest Territories (NWT). A number of sites were transferred to the GNWT, while others remained under federal jurisdiction.

The Devolution Agreement sets out five categories of contaminated sites in the NWT:

  1. Released sites are sites that were transferred to the GNWT through Devolution on April 1, 2014 and are now the responsibility of the GNWT.

  2. Remediated sites are sites that were transferred through Devolution to the GNWT on April 1, 2014 and are now the responsibility of the GNWT, with warranties from Canada in place.

  3. Excepted waste sites are sites on GNWT land that were identified for additional negotiations between Canada and the GNWT. Financial liabilities for these sites were not transferred to the GNWT. These sites include Ptarmigan Mine, Tin Mine, Tom Mine, Crestaurum Mine, Rodstrom Mine and Burwash Mine.

  4. Sites requiring remediation are sites on Canada’s land that will not be transferred to the GNWT until remediated by Canada and the GNWT agrees to accept the sites.

  5. Operating sites are sites on GNWT land, however there is the possibility to transfer the liability back to Canada if the operator no longer exists and there is environmental liability associated with the site. If liabilities are identified with abandoned Operating Sites, the GNWT may open negotiations by March 31, 2019 with Canada on the assignment of the liability and the remediation of the site.

In addition to these Devolution Agreement sites, GNWT departments have their own contaminated sites related to activities that were carried out on GNWT lands prior to Devolution.

What is the remediation process for contaminated sites in the NWT?

The GNWT determines remediation approaches based on land use, the feasibility of remedial technologies, cost, and public and regulatory acceptance. Remediation is guided by the applicable environmental standards and legislative requirements.

The GNWT has adopted a risk-based approach to the management of contaminated sites. The objectives of a risk-based environmental management approach are to assess risks to human health and the environment and to implement risk management solutions considered to be protective of those risks. This involves identifying the contaminants of concern, identifying potential receptors, determining potential exposure pathways, and estimating the level of risk based on the pathways. In addition, the risk-based approach implies a prioritized allocation of resources within the GNWT.

The risk-based approach incorporates several components including site identification and characterization, detailed site investigations and risk assessment, evaluation of different risk management strategies, implementation of a selected management strategy, assessment and monitoring. These components are realized through a nine-step process known as the “Steps for Managing a Contaminated Site”. These steps identify scientific tools and documents that are available for use in the management of GNWT contaminated sites, of which, only the initial assessment steps may be required in the event a risk management option takes priority over further remedial activity. Risk management of a contaminated site may still be subject to a monitoring requirement.

Steps for managing contaminated sites:

  1. Identification of a Site – A site is identified as a potential contaminated site.

  2. Phase I Environmental Site Assessment (ESA) - The process, as outlined in CSA Standard Z768-01, by which a qualified person determines whether a property is, or may be, contaminated. This is most often completed through a records review and site visit. Phase I ESA reports must be submitted to the applicable regulatory authority.

  3. Phase II ESA - The process, as outlined in the CSA Standard Z769-00, by which a qualified person characterizes, determines concentrations, delineates and quantifies contaminants on a site. The Phase II ESA reports must be submitted to the appropriate regulatory authority.

  4. Human Health and Ecological Risk Assessment (HHERA) – HHERAs are typically required when removal of a contaminant of concern is deemed extremely difficult and/or cost prohibitive. If required, an assessment by a qualified person determines the nature and probability of adverse health effects on humans and the ecosystem if exposed to contaminants identified by the ESAs. HHERA reports must be submitted to the applicable regulatory authority.

  5. Risk Management Plan (RMP) – A RMP would follow the assessment phases supported by an HHERA. This would also allow for a tailored approach, considering remediation and/or monitoring requirements.

  6. Remedial Action Plan (RAP) - A RAP is a plan that identifies site specific remedial objectives and options for a contaminated site; outlines their feasibility; describes a preferred conceptual remediation plan and monitoring plan; and, if appropriate, requirements for on-going site management. The RAP needs to be submitted to the applicable regulatory authority for review and approval.

  7. Remediation – Includes performance of the site remediation works carried out by consultants and contractors in accordance with the approved RAP, engineered designs, and specifications. A remediation report detailing activities completed must be submitted to the appropriate regulatory authority for final clearance.

  8. Monitoring – Includes any post-remediation inspections, monitoring and/or maintenance activities that may be required. Monitoring reports generated need to be submitted to the appropriate regulatory authority.

  9. Site Closure – Upon completion of both remediation and monitoring, or if post-remediation monitoring is not required, a site closure report must be completed and submitted to the appropriate authority for site closure approval. This will need to be completed for all regulatory authorizations.

How does the GNWT prioritize the remediation of its contaminated sites?

The GNWT decides which contaminated sites to prioritize based on levels of risk to people, property and the environment.

The risk of each contaminated site is reviewed annually, taking the following criteria into account for each site:

  • Human health and safety
  • Concerns of Indigenous peoples, northern residents and stakeholders
  • Impacts on the environment
  • Financial and legal obligations

Consequences for each criteria are identified, and the severity and likelihood of these consequences are determined. This analysis establishes the risk level for a site.  

Sites ranked high and medium risk are priority to action for the responsible GNWT department. Action on high risk sites should occur as soon as possible. Action on medium risk sites should occur within 2 to 3 years.