Minnova Inc. Properties
Years of Service
Metall Mining Corporation, prior to finalizing the purchase of Kerr Addison's interests in Minnova Inc. in 1992, performed a due diligence assessment of the properties and assets of Minnova. As part of this assessment, Metall Mining required an assessment of the potential liability associated with each property to identify the major existing and potential environmental compliance, violation or closure concerns.
Dr. Robertson was the Project Principal and Senior Technical leader of the SRK team which was retained by Metall Mining to conduct an environmental liability assessment and to estimate closure costs of Minnova's properties. The study included four operating mines, 10 past producers, eight advanced exploration, and four exploration sites in five provinces and Washington state. To perform this evaluation within Metall Mining's schedule required the mobilization of three teams, each with a diversity of skills to review and assess all major aspects of environmental liability. Our preliminary findings and closure costs were presented to Metall Mining and to Minnova three weeks after the project started and a final report issued three weeks later.
A pre-acquisition site reconnaissance was conducted to assess current and potential issues of environmental liability. Eighteen sites were visited including were made for producing mines or former producers (properties with major surface disturbances or accumulations of tailings and waste rock), as well as for exploration sites with significant surface or underground development. Inspections were made of the major mine and mill components, the property compliance data was reviewed and site personnel interviewed. Since many of the mines recovered base metals from sulphide ores, a number of the properties had concerns regarding the potential for acid rock drainage (ARD), particularly after closure. This is of particular concern for older sites, as the prediction and control of acid rock drainage is a relatively new science and requirement for mines. Therefore, much of the effort in performing the environmental liability assessments was devoted to ARD. Closure plan options were developed to address the major issues, with an estimate of the costs for implementation of the recommended options. Regulatory authorities were contacted for all sites to identify any concerns that they might have.
In assessing financial liability, compliance under current permit or regulatory requirements was assessed and also the additional environmental liability considered likely in the near future (less than 10 years) under the prevailing regulatory trends. These were non-sampling assessments, based on field observations and technical review of the main components at the site.
Consequently, the liability assessments and cost estimates relied, to a large extent, on the experience and engineering judgement of our investigation teams. The estimated closure costs were summarized in terms of capital costs for mine, mill, mine rock, tailings and other components, as well as for a bond amount which must be set aside to provide a perpetual fund for long term maintenance of a site.