Sustainability analysis of remediation and reclamation of Maurliden mine using the SCORE method
Examensarbete för masterexamen
Infrastructure and environmental engineering (MPIEE), MSc
Mines in several years of functioning produce a large quantity of waste materials containing contaminants that are harmful to different ecosystems. The study aims to analyse two suggested remediation alternatives by Boliden AB for the Maurliden mine location in the central part of the Skellefteå field in Norsjö from a sustainability perspective. Maurliden is an open pit mine in a sulphide deposit with zinc being the primary mined metal along with gold, silver, copper, and lead. The mine is currently subject to remediation measures with fewer activities going on like the treatment of wastewater from the mine at the facility. This sustainability study to compare remediation measures is made by implementing the SCORE method, a multi-criteria analysis method for evaluating and comparing the sustainability performance of remediation alternatives in the environmental, social, and economic domains. In the SCORE analysis, two alternatives have been studied. These two alternatives have been compared to a reference alternative representing no action, i.e., that the site remains in its current state. Remediation alternative 1 is where the open pit is backfilled with the waste rock from the mine site and the left-over waste rock is moved to the north of the mine site and qualified covered. Remediation alternative 2 is where the open pit is backfilled with a paste mixture of mine tailings from the Boliden area, water, and cement, and all waste rock from the site is moved up north and qualified covered. Both measures are associated with positive and negative social and environmental effects, but alternative 2 predominantly showed a higher positive sustainability score as compared to alternative 1. The remediation alternatives are generally associated with positive local environmental effects, both because of the implementation of the alternative and the reduction of the source contamination. The secondary effects, due to the emission to air, use of non-renewable natural resources, and production of non-recyclable waste differ between the measures where lesser emissions take place in alternative 1 and less virgin materials are used in alternative 2. The study comprises the quantitative and qualitative assessment of environmental and social domains and the qualitative assessment of the economic domain. Therefore, from environmental and social points of view, alternative 2 is the best remediation measure but from an economic point of view, due to insufficient data, it is difficult to comprehend which alternative that is the best. A sensitivity analysis showed that if the social or environmental domain is weighted lower/higher, the ranking of the alternative remains the same. Only when the social criterion, local acceptance is included in the scenario 3, the ranking of the alternatives changed. This explains that the opinions of the local population strongly influence the ranking of the alternatives. The main recommendation based on the results of the SCORE analysis is that alternative 2 is the most sustainable measure. However, it should be emphasized that before a final decision on which the alternative that is the most suitable is made, it is important to assess which is the most sustainable alternative in terms of the economic domain too.
qualified cover , source contamination , SCORE , Sustainable remediation , mine closure , tailings , waste rock