A tool for all seasons

With over $41.1 billion dollars in revenue each year at stake (according to Natural Resources Canada), Canadian mining companies have a vested interest in the way land is used and how it is left when mining projects are completed. Conducting a risk assessment at various stages of a mining project can be used to help shape decisions throughout the life of a mine, from the planning phase to closure and remediation, thereby avoiding regulatory liabilities or unnecessary expenditures.

What is risk assessment?

Risk assessment is a standard process accepted by regulators. It is a tool for identifying how emissions or releases from a site can impact human and ecological (that is, wildlife and aquatic life) health, including chemicals for which no guidelines are available. Risk assessment can be used to prioritize issues at a site or to guide decisions about mitigation and monitoring. It can also be used to compare the costs and benefits of various risk management options (including remediation), helping a company understand and manage its liability on a site. Public concerns (such as the contamination of traditional foods) can be included, incorporating stakeholder input into the scientific process.

The process combines information on the amount of a substance to which people or wildlife are exposed and the toxicity of that substance. The combination of this information is an estimate of the potential for an adverse effect. Information on intake comes from local sources of how much people and wildlife eat and spend time in the area of the mine site, and measurement of the concentrations of chemicals of concern in soil, plants and fish tissue. When this information is not available, conservative estimates are used. Similarly, toxicity information is obtained from databases set up and reviewed by government agencies. The combination of site-specific and standard information results in a risk assessment that is specific to the question at hand, but maintains a standardized method.

Throughout the stages

Prior to construction and operation of a mine located on crown land, an environmental impact assessment (EIA) is required under the Canadian Environmental Assessment Act. The EIA requires an evaluation of the potential for the proposed project to harm the environment such as water and air. Potential air and water quality changes must then be assessed for their potential to pose health risks to people, wildlife, and fish that might use the project area. This is where a risk assessment can be used for mine-site planning and licensing.

The purpose of a risk assessment is to identify whether emissions from the proposed mine might cause health effects. If unacceptable risks are identified, then changes to the mine operation plans can be made. For example, changing the location of an emission stack can decrease air emissions in a nearby community.

During the planning stages, the risk assessment process provides an opportunity to address community concerns and include traditional knowledge. Discussing the assessment process with stakeholders helps to establish a good working relationship with them.

Canada has federal and provincial regulatory requirements that vary depending on location. Risk assessment professionals understand these regulations and can help companies clarify potential roadblocks during the licensing process.

Even the best-made plans don’t always work out. Unforeseen events during the operation of a mine can cause changes to the local environment. For example, the need to divert operation emissions may cause a temporary increase in community air concentrations, or seepage may be discovered during monitoring activities. Risk assessment can be used in these situations to address concerns about increased health risks, and to identify the best course of action.

When resources are depleted, mine managers must plan for the closure and abandonment of the site. Currently, mine operators are required to post a bond with licensing regulatory agencies to ensure that when the site is abandoned it is cleaned up to acceptable levels. Many regulatory agencies require that a risk-based approach is used to ensure that potential risks to human and ecological health are reduced. One additional benefit for using risk assessment at the closure phase is to identify the areas that pose the greatest risks and should be prioritized for remediation.

Case study for remediation planning

The Tundra gold mine, 250 km northeast of Yellowknife, N.W.T., is an example of how risk assessment was used in a remote location for an abandoned mine. The only access to the site is by air, and by the winter road from January to May.

Tundra was the first Barrenland gold mine, operating from 1964 to 1968. From 1983 to 1987, ore from a mine 5 km to the north was sent to the mill at Tundra for processing. In 1987, the mine and mill were closed permanently and abandoned. In 1990, Royal Oak Mines Inc. purchased Giant Yellowknife Mines Ltd., which included the Tundra property. Royal Oak Mines filed for bankruptcy in 1999 and the responsibility for the site was transferred to the federal government.

During its operation, the Tundra mine impacted both aquatic and terrestrial environments. Indian and Northern Affairs Canada (INAC) is developing a remediation plan for the site. In support of the remediation plan, Golder Associates Ltd. conducted field investigations to determine current conditions at the site. Surveys were done to identify wildlife that use the site, fish community, and indicators of fish health in the lakes around the mine site. Soil, plant, sediment, and fish samples were also collected. Water quality data were made available from monitoring done by INAC. All of the information obtained during the terrestrial and aquatic investigations was evaluated using a risk assessment approach. Areas within the mine site were then ranked based on the potential terrestrial and/or aquatic risks. The site ranking enabled INAC to prioritize sites for remediation.

The Tundra mine site area, including four downstream lakes, was categorized into 12 areas of potential environmental concern (APEC), based on historical activities. The purpose of categorizing the study area was to evaluate risks based on specific attributes of each APEC and/or distance from mine site. Risks for humans, wildlife and aquatic life were estimated for each APEC and given a ranking. In addition, risks at each APEC were compared with estimated risks at a reference location, which was not impacted by mine activities.

The benefit of prioritizing risks for a number of small areas is that it enabled INAC to focus efforts and resources on those areas of the site that pose the greatest potential risk to humans and the environment. This was a particularly useful approach since the amount of time for conducting remediation activities is limited by access the site. Furthermore, the risk assessment results helped INAC understand the potential exposure of people, wildlife and fish to arsenic and other contaminants resulting from the former mining operation. This cost-effective approach helped to select the right remediation options quickly, and provides a framework for future discussions with stakeholders.

Cindy Robinson, B.Sc., P.Biol., is a toxicologist in the Calgary office of Golder Associates Ltd. She can be reached at tel. 403-299-5600; cindy_robinson@golder.com.