Prace Mine rehabilitation project
Learn about the environmental assessment process for the rehabilitation of mine hazards at the Prace Mine.
Current status
Statement of completion
Project Summary
The Prace Mine (AMIS #07976) is a former silver-lead mine that operated from 1973 to 1988. The property was historically referred to as Sill Lake Mine due to its proximity to Sill Lake, situated approximately 300 metres north of the mine.
The mine is in Vankoughnet Township, approximately 25 kilometres north of Sault Ste. Marie and 1.5 kilometres southeast of Robertson Lake. The property is accessed using an approximately 2 kilometres gravel road located off Robertson Lake Road.
The mine historically featured:
- two adits
- two raises
- a stope to surface
- an open cut
- a tailings management area
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. Two of these mine features, an exploration adit and a raise, were previously rehabilitated in accordance with the requirements of the Mine Rehabilitation Code of Ontario (Ontario Regulation 240/00) and no further rehabilitative work is required.
Although evidence of past rehabilitative activities is apparent at several of the other mine hazards, the current condition of the features does not satisfy the requirements for final closure and certification in accordance with >O. Reg. 240/00. In addition to these hazards, various debris associated with historical mining activity remains throughout the property, including buried tarps and building materials.
Proposed rehabilitation activities
The purpose of the project is to rehabilitate the mine hazards at the Prace Mine property to eliminate the risk to the public.
Mine hazards proposed for rehabilitation include:
- adit
- raise
- open cut
- stope to surface
- crown pillars
All remaining debris associated with the historical mining activities will be removed and disturbed areas allowed to revegetate and return to pre-disturbance condition.
The rehabilitation of the tailings management area is excluded from this rehabilitation and will be assessed as part of a separate class environmental assessment.
Open cut, stope and stope crown pillar
Bat exit surveys, completed in 2023 by engineering firm WSP, suggest that the stope to surface is used by bats as a potential hibernaculum (overwinter habitat).
The proposed rehabilitation strategy for the stope is fencing that meets the specifications outlined in O. Reg. 240/00. The fence perimeter will:
- encompass the stope, as well as the stope crown pillar and open cut
- eliminate the risk to public safety
- 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.
Raise
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 the code. The removal of the existing cap is needed prior to the construction of the new concrete cap.
The cap installation will be completed in the summer of 2024.
Adit
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 O. Reg. 240/00 for final closure.
The adit does not support bat overwintering habitat due to its flooded condition. This means the proposed rehabilitation strategy for the adit and adit crown pillar is to backfill. The work will occur in the summer of 2024.
Other improvements
Access improvements have been completed as part of previous investigation work. We anticipate 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.
All remaining debris associated with the historical mining activities will be removed and disposed of in accordance with applicable regulations. Disturbed areas will be allowed to revegetate naturally and return to pre-disturbance condition.
Proponent
Ministry of Mines
Location
Vankoughnet Township, Algoma District
Type
Bulletin
Reference number
Environmental Registry of Ontario #: 019-7902
Contact
Michaela Haring, Environmental Planner
Mine Rehabilitation Section
933 Ramsey Lake Road
Sudbury, Ontario
P3E 6B5
Email: Michaela.Haring2@ontario.ca
Notice of opportunity to provide input on a category B project (2023)
We invite you to comment on the Prace Mine Rehabilitation Project.
The proposed rehabilitation activities have been screened as a category B project. The undertaking is being carried out in accordance with the Class Environmental Assessment for Activities of the Ministry of Northern Development and Mines under the Mining Act (PDF, amended 2018).
We have identified several environmental effects associated with the undertaking, which can be mitigated using standard measures. A summary of negative environmental effects and proposed mitigation measures that would negate or reduce their significance is provided in the Project Description, which you can find with the supporting material for this project on the Environmental Registry of Ontario.
You are invited to provide input and express any concerns about this proposed project. For more information or to submit comments, visit the posting for this project on the Environmental Registry of Ontario or contact:
Michaela Haring, Environmental Planner
Mine Rehabilitation Section
933 Ramsey Lake Road
Sudbury, Ontario
P3E 6B5
Sudbury, Ontario
P3E 6B5
Email: Michaela.Haring2@ontario.ca
Your privacy
Personal information you provide in a submission (such as name, address and telephone number) and your views and opinions are being collected by the ministry under the authority of the Environmental Registry of Ontario for the purpose of engaging in public consultation and making decisions regarding the project.
Your personal information may also be shared with the Environmental Approvals Branch of the Ministry of the Environment, Conservations 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:
Michaela Haring, Environmental Planner
Mine Rehabilitation Section
933 Ramsey Lake Road
Sudbury, Ontario
P3E 6B5
Email: Michaela.Haring2@ontario.ca
Statement of completion
We have completed our assessment for the proposed rehabilitation of mine hazards at the abandoned Prace Mine (AMIS #07976). 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 is in Vankoughnet Township, approximately 25 kilometres north of Sault Ste. Marie and 1.5 kilometres southeast of Robertson Lake.
The purpose of the project is to rehabilitate the mine hazards at the Prace Mine to eliminate risks to the public. Mine hazards proposed for rehabilitation include the adit, raise, open cut, stope to surface and crown pillars. All remaining debris associated with the historical mining activities will be removed and disturbed areas allowed to return to pre-disturbance condition.
Bat acoustic studies completed at the stope to surface confirmed that bats use the underground workings as a hibernaculum. The stope to surface is the only feature identified that provides bats access to the underground workings. The currently planned rehabilitation activities will not impact the long-term use of the bat overwintering habitat.
The rehabilitation activities will include the following.
- The installation of fencing that meets the specification outlined in the Mine Rehabilitation Code under Ontario Regulation 35/24 (previously Ontario Regulation 240/00) around the stope to surface, stope crown pillar, adit crown pillar and open cut. The fencing will minimize inadvertent access to the mine, while protecting the bat overwintering habitat.
- The concrete capping of the raise. The existing cap would be removed prior to the construction of the new cap.
- The backfilling of the adit. The trench leading to the adit will be dewatered to provide access to the adit and all existing backfill, timber and steel mesh removed. The contractor will be responsible for determining how to manage the wastewater.
The fencing installation will require tree and vegetation removal extending approximately 3 metres on either side of the fence perimeter. We anticipate 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. All remaining debris associated with the historical mining activities will be removed and disposed of in accordance with applicable regulations. Disturbed areas will be allowed to revegetate naturally and return to pre-disturbance condition.
We assessed this undertaking as a Category B, in accordance with the Class Environmental Assessment for Ministry of Northern Development and Mines Activities under the Mining Act (Class EA).
Consultation summary
We distributed consultation letters to government agencies, Indigenous communities and other interested persons on February 16, 2024. In addition, we posted a Notice of Opportunity to Provide Input as a Bulletin Notice on the Environmental Registry of Ontario (ERO #019-7902) and referenced it on the Mining Act resources webpage. We supported the notice and letters with a description of the project that included a summary of potential negative environmental effects associated with the undertaking and proposed mitigation measures that would negate or reduce the significance of the environmental effects. We provided all parties consulted with an opportunity to provide input and express concerns related to the project over a 30-day comment period.
The Ministry of Natural Resources and Forestry (MNRF) indicated that the Robertson Lake Road Cliff (G-04) Area of Natural and Scientific Interest (ANSI) is situated 2 to 3 kilometres west of the mine. Project activities are not expected to impact the ANSI.
The MNRF provided information related to fish species in nearby waters and advised that there is the potential to impact fish and fish habitat if the adit trench wastewater is discharged to the environment. The contractor will be responsible for determining how to manage the wastewater during the dewatering activities. Considering the minimal amount of water to be removed, it is possible that the water may be hauled off site for disposal. If the contractor chooses to discharge the water into the environment, the water will be sampled to ensure no impacts to the environment. In addition, erosion and sedimentation measures would be implemented, as well as energy dissipation measures to deflect, scatter and neutralize the erosive force of the moving water. We included mitigation measures as part of the Class EA.
The Ministry of Environment, Conservation and Parks (MECP), Species at Risk (SAR) Branch provided comments related to the projects impact on species at risk and compliance with the Endangered Species Act (ESA 2007). We have summarized the following key comments received from the MECP SAR Branch and our response and resolutions:
- MECP raised concerns related to the dewatering of the trench and impacts to Blanding’s Turtle. A Species at Risk survey completed by engineering firm WSP in 2023 identified that the substrate along the mine access road may be suitable for turtle nesting. However, no evidence of turtles was observed. The project area is situated in the northern boundary of the Blanding’s Turtle range and there are no previous occurrences of Blanding’s Turtle overlapping with the site. The trench feature extending to the adit would not support Blanding’s Turtle habitat. The trench will be allowed to flood again naturally after the adit has been backfilled.
- MECP advised that Blanding’s Turtle active season is from April 15 to October 15. They recommended that exclusionary fencing be installed outside of the active period. We will review the project area to determine locations for fencing, as needed.
- MECP recommended that tree and vegetation removal activities be completed after September 15 to buffer the swarming period of bats. We incorporated the recommended timing window for tree and vegetation removal into the Class EA.
- MECP asked if uncapping the raise could provide suitable habitat for bats and, if so, could a bat-friendly rehabilitation measure be alternatively utilized. We advised MECP that replacement of the cap remains the preferred rehabilitation option for the raise. Utilizing a bat friendly measure would have the potential to impact the microclimate of the underground workings and suitability of the existing hibernaculum.
We will continue to consult with the MECP, SAR Branch to ensure that project activities do not contravene with the ESA (2007).
The MECP Environmental Assessment branch provided a letter acknowledging that the project is following the approved environmental planning process for a Category B project under the MINES Class EA. The updated Areas of Interest document (August 2022) was provided regarding the MECP’s interest with respect to the Class EA process. We have reviewed the Areas of Interest document to ensure we address all MECP’s interest with respect to the Class EA process. We provided the statement of completion to the MECP’s Northern Region EA notification email.
The Ministry of Citizenship and Multiculturalism (MCM) advised that if the project exhibits archaeological potential, then a licensed archaeologist will undertake an archaeological assessment. The screening completed for this project identified no known or potential archaeological resources. Similarly, the project screening has identified no known or potential built heritage resources and cultural heritage landscapes. We included the completed screening checklists for archaeology and cultural heritage landscapes in the Class EA report.
We did not receive other comments that would affect the currently planned project. We will implement the project as described in the project documentation.
Approved by:
April 12, 2024
Marc Stewart
Senior Manager, Mine Rehabilitation Section
Ministry of Mines
933 Ramsey Lake Road, Sudbury, Ontario
Email: Marc.Stewart@ontario.ca