Geomembrane displacement monitoring system installed in a multilayered cover at the Aldermac mine site

Abstract

The abandoned Aldermac mine site, located in the Abitibi- Témiscamingue region of Québec, Canada, is a former polymetallic mine that operated in the 1930s. Over the decades, the sulfidic mine wastes produced by the mine have been exposed to atmospheric conditions, leading to the generation of acid mine drainage (AMD) and contamination of the surrounding environment. In 2008–2009, reclamation works were initiated by the Québec government with the implementation of different techniques based on the characteristics of the different sectors of the mine site. In the southern sector, the production of AMD from the mine wastes pile is controlled by a multilayered cover system, including a 1.5 mm-thick textured high-density polyethylene geomembrane, aimed at limiting ingress of water and oxygen. In 2021, work was carried out to instrument the cover system with an innovative displacement measurement system that was developed and applied to the geomembrane along a sloping transect. The system allows continuous measurements of geomembrane displacement at three locations. This article discusses the installation of these instruments and presents preliminary results. Displacements over a 1-year monitoring period ranged from approximately 4 mm downslope to 32 mm upslope. This corresponded to strains ranged from approximately 0.01% contraction to 0.05% tension.