Evaluating the Relative Risks of Pit Reclamation Alternatives at the Golden Sunlight Mine (Montana, USA); A Multiple Accounts Analysis

摘要

A Multiple Accounts Analysis (MAA) was initiated to develop and evaluate potential alternatives for the pit reclamation at the Golden Sunlight Mine, Montana USA. Seven alternatives were developed and ranged from those that included pit backfill (of various scenarios) to those that retained an open pit or a pit lake (a.k.a. pit pond). One of the issues of most concern and most uncertainty was the potential impact or risk to downgradient surface water and groundwater as a result of reclamation; and the ability to make an assessment of the relative risks of any one alternative over the others. The term 'risk' here was defined as a general term implying legal risk (e.g. exceedances of standards); as well as other, less quantitative risks such as the risk of creating a bad public perception, local, regional or international outcry, or regulated procedural changes in on-going operations or reclamation. Risks to down-gradient waters in these scenarios were variably dependent on technical issues such as different mine water collection schemes, including various methods of and locations for collection associated with the different alternatives. In order to assess these risks, in combination with other advantages and disadvantages of each alternative, a multi-stakeholder group involving members from the mining company, the public, state and federal regulators, consultants and representatives from 5 NGO's was formed and tasked with the relative evaluation of potential alternatives using the MAA.