MWH succeeded in the acquisition of the FGMI Pre-feasibility (PFS) and Groundwater Interception System Evaluation contracts. The PFS work was initiated during the summer and fall of 2013 and provided surface and groundwater hydrological assessments for a large-scale gold mine near Fairbanks, Alaska.
The MWH on-site team was resourced out of multiple offices, showcasing our global workforce. Baseline characteristics of surface and groundwater resources were evaluated and defined, for known locations, and then used to determine where additional surface and groundwater stations needed to be installed. A total of eight groundwater monitoring wells, three thermistor strings (installed to evaluate permafrost depths), and 13 surface water monitoring stations were established. The groundwater monitoring wells will be used for groundwater characterization throughout the footprint of the potential mine plan to evaluate flow directions, depth, formation permeability, recharge and discharge zones and geochemistry. The thermistor strings will be used to determine depths to permafrost, which can often reach 150 feet along the north facing slopes and can also complicate the groundwater flow which plays an important part in future pit dewatering strategies. The surface water monitoring stations, accessed primarily on ATVs or hiking, will be used to characterize baseline chemistry, temperature, and flow rate data.
In addition to the PFS effort, MWH performed a groundwater Interception System Evaluation for FGMI. Background data and installation of a test pilot borehole were completed in the summer and fall of 2013 to evaluate the best way to upgrade the TSF system with more efficient wells which will allow more groundwater to be extracted. Numerous airlift and recovery tests were conducted during the borehole drilling to collect groundwater flow rates and impacted water chemistry. This data will be utilized in the future for the interceptor well system.
The subzero temperatures combined with the remote site, which can be covered with up to 10 feet of snow/sheet ice for eight months of the year, took careful planning by MWH hydrogeologists and field staff to maintain site safety, supplies and equipment.
- Hydrological assessments
- Definition of baseline characteristics of surface & groundwater
- Groundwater monitoring well installation, surface water station establishment, thermistor installation, and interceptor borehole testing.
- Interceptor Well Design
- Successful collaboration between multiple MWH offices to accomplish the initial groundwater characterization.
- Successful staffing of four month field effort.
- Fairbanks, Alaska, United States
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