Evaluation of Ecological Risks and Benefits of Revegetation of the Thetford Mines- Phase 1

Interim Report 1 – Literature review

EXECUTIVE SUMMARY

This literature review is the first interim report of the project “Evaluation of Ecological Risks and Benefits of Revegetation of the Thetford Mines- Phase 1”. This project is proposed as the first phase of a multi-stage assessment to evaluate the feasibility of establishing vegetation covers on asbestos tailings piles in the Thetford Mines area. The literature review determines current state of work and identifies knowledge gaps.

Four previous revegetation projects in the Asbestos-Thetford Mines area are reviewed. These projects include:

1. A comprehensive field and laboratory research in the 1970’s that was funded by Quebec Asbestos Mining Association and Environment Canada;
2. A field reclamation project done in the 1980’s by the Centre Spécialisé en Technologie Mineral du College de la Region de l’amiante;
3. A green-house pot-trial research in the 1990’s in Laval University;
4. A six-year large scale project in Jeffrey Mine from 2003 to 2009.

These past projects have covered a broad knowledge base with respect to revegetation techniques. Mineralogical characterization and physical-chemical analysis of asbestos tailings have elucidated the factors that limit vegetation establishment. The most successful plant species have been identified and different amendment recipes and procedures have been developed for large-scale reclamation.

More research is needed to further understand the long term effect of weathering processes on the bare asbestos tailings piles. The potential ecological risks of erosion and benefits of carbon capture and nitrogen fixation from establishing vegetation covers need to be quantified. There are also knowledge gaps in understanding the transport of contaminants across the tailings-ground water interface and long-term release of nutrients and metals from the vegetation-covered tailings.

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