Abstract
Closing mine properties is complex, expensive and can sometimes require in perpetuity ownership of hazards and maintenance requirements. Active and abandoned mine properties host several types of physical hazards, such as mine openings to surface (shafts, raises, adits, etc.), near surface mine workings (i.e., crown pillars), open pits, waste rock piles, and tailings storage facilities. Specifically, the rehabilitation of these mine physical hazards requires multidisciplinary teams, and the integration of these various expertises can result in innovative solutions for rehabilitation.
These physical hazards are often problematic as they can present risks to the general public (i.e., injuries, fatality, damage to property) if left un-rehabilitated. These hazards might also have been a low-risk situation during operations or directly after closure but can become a high risk if they are left to degrade over the following years and/or decades. In some examples the transferring of surface and mining rights to different owners may not include sufficient information regarding the stability condition or risk associated with the historical mine physical hazards on the property.
Over the past several decades Golder WSP teams have been involved in locating, investigating, assessing long term stability, developing specific risk mitigation and remediation measures, and remediating physical hazards. During that period, the standard requirements for mine closure have evolved and became more specific and stringent, often due to past failures and the overall increased knowledge and experience in the industry and from the government agencies regulating mine closure.
Recent rehabilitation project experiences have shown that developing an overall mine property rehabilitation strategy that considers all the physical mine hazards on a site or in an area can have cost saving benefits and technical efficiencies. Optimizing the rehabilitation strategy for all hazards with all disciplines means avoiding duplication of cost and effort. This presentation will describe some examples of the investigation approaches, stability assessments, and remediation measures implemented for physical hazards for mine closure.
The following project examples will be discussed:
- Investigating stopes and crown pillars on historical mine properties and rehabilitation using cemented fill developed locally for the project, or transported to site.
- Investigating historical stopes, shafts, raises and crown pillars in urban locations (under roads, parking lots, near and under buildings) and developing customised remediation solutions.
- Remediation solutions of mine hazards that have over time become habitats for bat species at risk.