Reclaim an abandoned mine site

An abandoned mine site is a mine site that no longer has a known or solvent owner and for which the costs of reclamation are now borne by the government. It is part of the “environmental liabilities of the State”. It was to avoid this historic legacy of abandoned mine sites that the law surrounding mine reclamation was put in place.

A number of steps must be taken by the government before reclaiming an abandoned mine site.

1- Data collection

The first step is to conduct environmental assessment studies. These studies help identify contamination risks and their locations, the presence and extent of contamination, as well as resulting issues and impacts.

Related studies may be required, such as geotechnical studies, rock mechanics, hydrogeology, etc. They will be tailored to the specific conditions of each abandoned mine site.

2- Scenarios and reclamation plan

Once the data is collected, reclamation scenarios are developed. They must take into account the specific features and issues of the site under study.

The final selection of reclamation methods is based, among other things, on a risk analysis, expert consultation and validation studies, as required.

All permits and authorizations to carry out the work must be requested and obtained from the various departments and agencies (provincial and federal) as well as the municipalities concerned. Engineering plans and specifications for construction are then prepared.

3- Reclamation works

The selected reclamation solutions are then implemented. This step begins with the awarding of contracts to companies to carry out the work.

4- Post-closure monitoring and maintenance

Following the reclamation work and to ensure that the goals have been met, regular site inspections are scheduled. Environmental, agronomic, geotechnical monitoring, etc., may take place depending on the specifics of the sites. Maintenance work is also carried out, such as wildlife monitoring, bush clearing, culverts and canals cleaning, etc. Corrective work is also performed as required.

The main environmental problems of abandoned mine sites are the same as those of active mines. This may include, for example, the presence of mine drainage or the nature of the contaminants present, but also the spread of these materials due to lack of tailings impoundment or their historical design.

In addition to these known environmental issues, there may be a lack of available information on the mining activity carried out, the remoteness of the sites and concerns related to site security, such as unstable or insecure mine openings, physical instability of pit walls, waste rock piles or tailings storage facilities, or dilapidated infrastructure or buildings.