The rehabilitation of legacy mine sites is an ongoing challenge. Public safety and environmental protection are key considerations in the advancement of mine closure practices.
Eaton retained Golder to complete the progressive rehabilitation of their Edison Mine property in Ontario, Canada. The Ministry of Natural Resources and Forestry (MNRF) identified the underground mine workings as a potential location for bat hibernacula. A bat survey conducted by Golder confirmed the presence of bats, therefore the mine workings were designated as protected habitat for the species at risk, Little Brown Myotis and Northern Myotis. Due to this classification, three physical mine hazards (adit, shaft, and open cut) connected to the underground workings were to be preserved and left open to maintain access for these species. Given that conventional rehabilitation measures would either inhibit access to the underground workings by bats, or were not a permanent solution, a unique rehabilitation solution was required for these openings to surface.
Through a 16-month consultation process with Eaton, the Ministry of Northern Development and Mines (MNDM) and the MNRF, Golder designed an innovative bat cupola and bat gate solution, as well as a phased rehabilitation plan satisfying the interests of all those involved. The backfilling of non-bat habitat mine hazards on the site was also completed, using locally-sourced materials.
Challenges for the project included the rugged northern terrain, remote forested location, and difficult summer working conditions. To address this, the team focused on disciplined logistical planning. Over 40 helicopter lifts and several barge trips up the Montreal River were safely completed without incident while transferring materials for the bat gate and cupolas.
The progressive rehabilitation of the Edison Mine is protecting bat hibernacula for these species at risk and preventing inadvertent access into the underground mine workings, protecting the public’s safety. The two cupolas and adit gate are one of the first bat-friendly structures to be constructed for mine workings in Ontario.
Golder was awarded the 2018 Tom Peters Memorial Mine Reclamation Award by the Canadian Land Reclamation Association and the Ontario Mining Association for outstanding achievement in closure practices for work on the historic Edison Mine.
For more information about this project, you can check out “Bat Friendly Progressive Rehabilitation” from the Canadian Consulting Engineer Magazine, December 2018 issue.