Faro Mine Remediation Project
The Faro Mine Complex (FMC) is one of the largest abandoned mine sites in Canada and includes three open pits, about 320 million tonnes of predominantly sulphidic waste rock, and 55 million tonnes of sulphidic tailings. Most of the tailings are stored in a valley-fill deposit in the Rose Creek valley (aka Rose Creek Tailings Facility). The ore deposit was discovered in 1953 and the mine was in operation under various operators from 1969 to 1998. Most of the mine waste stored at the FMC is potentially acid-generating and the FMC is severely impacted by ARD/ML.
RGC has been involved in geotechnical, environmental, and hydrogeological studies at the FMC in support of closure planning since 1995. Under the guidance of Dr. Andy Robertson, RGC developed the first comprehensive closure plan (ICAP) for this site in 1996 and Dr. Robertson is now a member of an Independent Peer Review Panel (IPRP) that continues to review closure planning for this site. From 2003 to 2017, RGC assisted the Yukon Government in the execution and review of hydrogeological studies and the design, implementation, and performance assessments of several components of the site-wide SIS as part of care and maintenance or closure planning, including the S-Cluster SIS, ETA SIS, and Rock Drain SIS. RGC has also completed annual review of groundwater quality conditions across the FMC, as well as numerous targeted investigations of ML/ARD in the Rose Creek valley during this period.
In 2017, the federal government (CIRNAC) initiated an Environmental Assessment (EA) process for final closure of the FCM. CIRNAC retained a consortium of consulting firms (SRK/Golder) to assist with this closure work effort. Dr. Christoph Wels from RGC was retained by SRK as hydrogeology team lead for the closure team. Hydrogeological studies completed by RGC/SRK from 2017 to 2022 as part of EA closure planning have included:
- Multiple hydrogeological field programs (including drilling, hydraulic testing, and groundwater monitoring) to characterize the hydrogeology of the Rose Creek Valley aquifer
- Development of a 3D geological model of the Down Valley area (in Leapfrog) using over 200 drill holes.
- Recalibration of a water and load balance model for the Rose Creek Tailings Area (RCTA) to quantify current and future ML/ARD loading from tailings and waste rock seepage to the groundwater and surface water in Rose Creek valley.
- Development and calibration of a detailed local 3D groundwater flow model (in FEFLOW) used to support the design of a short-term and a long-term seepage interception system in the Down Valley area at the Faro Mine (DV SIS).
- Development and implementation of the performance monitoring program to confirm capture efficiency of the short-term DV SIS, verify system design and provide data to support 90% design of a long-term DV SIS.
The Down Valley groundwater model is regularly updated as new monitoring data becomes available to support ongoing refinement of the DV SIS design.
- Development of a water and load balance to determine water management, collection and treatment requirements for long term closure measures and funding
- Supervision of drilling, installation and development of pumping and monitoring wells
- Design and supervision of multi-day pump tests
- Numerical modelling of groundwater flow & solute transport
- Development and costing of a groundwater interception system and management plan
- Geochemical sampling and characterization of tailings and waste rock
- Design of geochemical control measures (covers, diversion works, contaminant collection ditches, swamps, dams, treatment plants, sludge disposal systems)
- Investigations of foundation conditions under critical structure, and sources and properties of construction materials
- Investigations of hydrological conditions and maximum probable flood, and other extreme events, determinations
- Design of physical control structures, water run off and control ditches, dams, spillways, pipelines and pumping stabilization measures
- Determination of stability of tailings dams, waste rock dumps and diversion channels and diversion structures
- Preparation of cost estimates for construction and closure fund establishment