Final covering of mine tailings by hdpe geomembrane
The project was part of mining site rehabilitation works performed at Louvicourt, near Val-d’Or, Québec. An abandoned pit on the site had been filled in with acidogenic tailings and contaminated soils. Studies had indicated that rainwater and oxygen penetrating unsaturated areas of the infill had resulted in a build up of acidified water, with suspended heavy metals eventually being found in the groundwater. As the geometry of the site did not allow for the installation of a capillary effect barrier, the solution was to install an impermeable 1.5 mm thick HDPE geomembrane to prevent water and oxygen from entering the tailings pile.
The mandate awarded to Groupe Alphard comprised the engineering design (plans and specifications) of the cover installation and the selection of geosynthetic materials adapted to project requirements, as well as the all related environmental and geotechnical engineering activities (stabilisation of the tailings pile, excavation of drainage trenches, etc.).In addition, Groupe Alphard were responsible for the production of the project CofA request, the management of the call for bids process, and the quality control of natural and geosynthetic materials used throughout the project. Following the selection of the contractor, Group Alphard provided works and environmental surveillance services for the duration of the covering and excavation works.
- Design and Detail Engineering
- Collection of information required for the engineering design of the cover;
- Collection of information and specifications required for the selection of the HDPE geomembrane;
- Design and detail engineering of the cover system: geometry, tailings pile stabilisation, drainage system, etc.;
- Production of plans and specifications for bids and construction;
- Production of tender documentation and detailed construction cost estimates;
- Monitoring, assistance and technical support (client and bidders) during the call for bids process
- Surveillance of Construction Works
- Provide continual surveillance during cover and geomembrane material installation works to ensure conformity with plans and specifications;
- Apply quality control and quality assurance procedures on natural and geosynthetic materials, including sampling and laboratory testing, to ensure conformity with plans and specifications
- Prepare and lead works kick-off meeting and worksite meetings;
- Monitor works in accordance with the works schedule provided by the contractor;
- Provide recommendations related to technical problems and provide guidance regarding the interpretation of plans and specifications;
- Verify and approve contractor quantities and declarations;
- Produce a list of non-conformities and recommend provisional approval of completed works;
- Perform electrical leak location (dipole method) on the geomembrane cover;
- Prepare works approval report and as-built plans.