Prace Mine Rehabilitation Project

Proposal details:

The Prace Mine (AMIS # 07976) is a former silver-lead mine that operated from 1973 to 1988. The property has also historically been referred to as Sill Lake Mine due to its proximity to Sill Lake, situated approximately 300 metres north of the mine. The mine site is accessed via a gravel road located off Robertson Lake Road, approximately 25 kilometres north of Sault Ste. Marie, Ontario.

The mine features an adit, raise, a stope, and an open cut. There are two crown pillars associated with the underground workings, one located west of the stope and open cut and another related to the adit. The purpose of the project is to rehabilitate the mine hazards at the Prace Mine property to eliminate the risk to the public. All remaining mining debris will be removed, and disturbed areas allowed to revegetate and return to pre-disturbance condition.

Bat exit surveys completed in 2023 suggest that the stope to surface is utilized by bats as a potential hibernaculum. The proposed rehabilitation strategy for the stope is fencing that meets the specifications outlined in Ontario Regulation 240/00. The fence perimeter would encompass the stope, as well as the stope crown pillar and open cut. The use of the fencing will eliminate the risk to public safety, while protecting the bat overwinter habitat. The fencing installation will require tree and vegetation removal extending approximately 3 meters on either side of the fence perimeter. The work is expected to occur in the fall of 2024.

The raise is currently concrete capped and in fair condition, however there are no records of its construction. The existing cap eliminates access to the underground workings by bats, lacks venting and therefore does not contribute to the microclimate of the potential bat hibernaculum. The preferred rehabilitation strategy for the raise is a concrete cap that meets the minimum specifications outlined in Ontario Regulation 240/00. The removal of the existing cap is needed prior to the construction of the new concrete cap. The installation of the cap will be completed in the summer of 2024.

The adit is currently flooded above the brow and access to the underground restricted due to the presence of timber, backfill and steel mesh. However, the quality of the backfill is not known and the current condition of the adit does not fulfill the requirements of Ontario Regulation 240/00 for final closure. The adit does not provide habitat to bats due to the backfill and flooded condition. As such, the proposed rehabilitation strategy for the adit and adit crown pillar is to backfill. The trench leading to the adit will be dewatered to provide access to the adit and existing backfill removed. The work will occur in the summer of 2024.

Access improvements have been completed as part of previous investigation work. It is anticipated that only minor vegetation clearing, and grading of existing mine roads will be needed to facilitate the access of heavy equipment to the areas requiring rehabilitation.

Public consultation:

You are invited to provide input and express any concerns about this proposed project. Comments must be received by March 20, 2024.

For more information or to submit comments please contact:

Michaela Haring, Environmental Planner
Ministry of Mines
Mine Rehabilitation Section
Telephone: 1-249-885-3631
Email: Michaela.Haring2@ontario.ca

Please note that personal information provided in a submission (such as name, address, and telephone number) and your views and opinions are being collected by MINES under the authority of the Environmental Assessment Act for the purpose of engaging in public consultation and making decisions regarding the project. The personal information may also be shared with the Environmental Assessment and Permissions Branch of the Ministry of the Environment, Conservation and Parks. The collection, use, and disclosure of this information are all governed by the Freedom of Information and Protection of Privacy Act. Questions about the collection of this information should be directed to the person listed above.